Compounds that show promise in mice with mutations may offer similar
The MIT Technology Review, January 11, 2010, by Emily Singer — Seaside Therapeutics, a startup based in Cambridge, MA, is testing two compounds for the treatment of fragile X syndrome, a rare, inherited form of intellectual disability linked to autism.
The treatments have emerged from molecular studies of animal models that mirror the genetic mutations seen in humans. Researchers hope that the drugs, which are designed to correct abnormalities at the connections between neurons, will ultimately prove effective in other forms of autism spectrum disorders.
“I think that fragile X-targeted treatments are at the cutting edge of reversing cognitive deficits in individuals with neurodevelopmental disorders,” says Randi Hagerman, medical director of the M.I.N.D. Institute at the University of California, Davis. Hagerman consults with a number of companies, including Seaside, that are developing treatments for fragile X syndrome. “This could lead to reversing intellectual disabilities and behavioral problems with this disorder,” she says. “That is extremely exciting.”
Fragile X is a genetic form of mental retardation caused by an abnormal expansion of part of the X chromosome. The disorder is rare, affecting about 1 in 4000 males in the United States and about 1 in 6000 females. But it is the most common known cause of autism–it’s responsible for 2 to 5 percent of cases, and is the most common inherited cause of intellectual disability.
The fragile X mutation blocks production of a protein called FMRP (fragile X mental retardation protein), whose normal task is to inhibit molecular activity at the connections between nerve cells. Loss of the protein appears to throws the system out of whack. “It’s like driving a car with your foot on the accelerator and no brake,” says Randall Carpenter, a physician and cofounder of Seaside. “There is too much activation of that pathway.”
In 2007, Mark Bear, a neuroscientist at MIT and cofounder of Seaside, and his collaborators discovered that they could reverse the deficits caused by the fragile X mutation in mice by turning down the activity of a receptor called metabotropic glutamate receptor 5 (mGluR5), found on the surface of brain cells. By doing this they effectively added a new brake to the system. Animals engineered to produce 50 percent less of this receptor suffered fewer seizures–a hallmark of fragile X–and had fewer brain abnormalities compared to mice producing the full amount of the receptor.
Dozens of academic labs across the globe have since shown that small molecules designed to block the activity of mGluR5 have the same effect, reducing abnormalities in mice with the fragile X mutation. Those abnormalities include seizures, atypical rates of protein synthesis, and other molecular glitches. While it’s not yet clear if there is a critical window during development for giving the drug, adult animals still benefit from the treatment. “These compounds have made remarkable changes in animal models of fragile X, rescuing abnormal synaptic connections,” says Hagerman. “We’re very hopeful it will do the same for humans.”
Seaside, which licensed some of these compounds from Merck, has just finished initial safety studies of one candidate. (Large pharmaceutical companies have been developing these molecules, called mGluR5 antagonists, for years for a variety of diseases, including schizophrenia and Parkinson’s disease. None have yet been approved for human use, however.) Seaside aims to begin studies in people with fragile X later this year or early in 2011.
Inspired in part by Bear’s work, pharmaceutical giant Novartis is also testing an mGluR5 antagonist in people with fragile X, as is Neuropharm, a pharmaceutical company based in the United Kingdom. “If we see even a percentage of what we see in the mouse, it will be an important treatment,” says Carpenter.
Seaside is also testing a second compound that dampens synaptic activity through a different mechanism–by mimicking the brain’s major inhibitory chemical messenger, known as GABA. Previous research has shown that a specific form of an existing drug called Baclofen, which activates GABA receptors and is currently used to treat muscle spasms, can reverse symptoms in mice with a mutation similar to fragile X. The company has just completed a clinical trial of the drug in 60 people with fragile X syndrome and expects results from the study in April. A second study of the drug in people with autism is also underway.
The company is funded almost entirely by an undisclosed family investment of $60 million, with $6 million from the National Institutes of Health. Carpenter says that Seaside has enough funding to take its compounds through clinical testing and approval. “We are prepared to do it ourselves,” he says. “But if there is a partnership that allows us to more rapidly advance compounds, then we would embrace that opportunity.”
While it’s not yet clear whether people with non-fragile X forms of autism would benefit from the same types of drugs, Carpenter and others say those people may share similar molecular problems. For example, genetic studies have linked some cases of autism to mutations in genes controlled by FMRP. Since autism is thought to be a collection of related diseases with different molecular causes, Seaside is looking for protein or DNA biomarkers in the patients in its trials that might predict who would benefit from the molecules being tested.
One theory for the cognitive impairment associated with fragile X, and perhaps with autism in general, is deregulation at the synapse, the connection between two neurons. Our ability to learn is dependent upon the tightly regulated ability to continually change the strength of synapses in response to new information. People with fragile X syndrome and other types of cognitive impairment have immature-looking synapses and inefficient signaling, says Carpenter. That means the brain is “interpreting almost everything that is happening as noise, rather than important information.”
- Vitamin C improves the speed and efficiency of mouse iPSC generation
- Adding vitamin C converts pre-iPSCs to iPSCs
- Vitamin C alleviates the senescence roadblock to reprogramming
- Human iPSC generation is also improved by vitamin C
- Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) by defined factors. However, the low efficiency and slow kinetics of the reprogramming process have hampered progress with this technology. Here we report that a natural compound, vitamin C (Vc), enhances iPSC generation from both mouse and human somatic cells. Vc acts at least in part by alleviating cell senescence, a recently identified roadblock for reprogramming. In addition, Vc accelerates gene expression changes and promotes the transition of pre-iPSC colonies to a fully reprogrammed state. Our results therefore highlight a straightforward method for improving the speed and efficiency of iPSC generation and provide additional insights into the mechanistic basis of the reprogramming process.
Animal development starts with the fertilized egg undergoing a programmed process of cell proliferation and differentiation that generates all cell types of an individual. This process was thought to be irreversible in mammals, but the cloning of Dolly proved that fully differentiated somatic cell nuclei can be reprogrammed back to an embryonic-like state by factors present in oocytes (Wilmut et al., 1997). More recently, Yamanaka and colleagues demonstrated that mouse somatic cells can also acquire a pluripotent state in vitro after the introduction of a defined combination of transcription factors that are highly enriched in embryonic stem cells (ESCs) (Takahashi and Yamanaka, 2006). Mouse iPSCs are similar to ESCs in most aspects and can generate entire individuals after tetraploid complementation (Kang et al., 2009,Okita et al., 2007,Wernig et al., 2007,Zhao et al., 2009). iPSCs have also been produced from other species including human and pig (Esteban et al., 2009,Takahashi et al., 2007,Yu et al., 2007), raising the possibility of clinical application of personalized stem cell-based therapies without immune rejection or ethical concerns. Human iPSCs also provide a unique platform for studying genetic diseases in vitro (Park et al., 2008). However, the low efficiency of iPSC generation is a significant handicap for mechanistic studies and high throughput screening, and also makes bona fide colony isolation time consuming and costly. The efficiency of alkaline phosphatase-positive (AP+) colony formation with the four Yamanaka’s factors (Sox2, Klf4, Oct4, c-Myc; SKOM) in mouse fibroblasts is about 1% of the starting population, but only around 1 in 10 of those colonies is sufficiently reprogrammed to be chimera competent (Silva et al., 2008). In human fibroblasts, only about 0.01% of cells transduced with SKOM form AP+ iPSC colonies (Takahashi et al., 2007,Yu et al., 2007). In our search for compounds that improve the efficiency of somatic cell reprogramming, we have found that a vitamin (Vc) that is highly abundant in our diet significantly increases mouse and human iPSC colony formation, at least in part by alleviating cell senescence.
- We show here that vitamin C, a common nutrient vital to human health, enhances the reprogramming of somatic cells to pluripotent stem cells. By adding Vc to the culture medium, we can now obtain high-quality iPSCs from mouse and human cells routinely. While our work was in progress, six independent laboratories identified cell senescence as a roadblock for reprogramming (Hong etal., 2009,Kawamura etal., 2009,Li etal., 2009,Marión etal., 2009,Utikal etal., 2009,Zhao etal., 2008), creating significant interest in finding compounds that alleviate cell senescence without increasing the risk of mutations. Vc reduces p53 levels during reprogramming and this may raise concerns regarding safety, but at least based on the parameters tested, our cell lines are devoid of noticeable side effects.
- We uncovered this new role of Vc by trying to correct increased ROS production in SKO-infected MEFs. Vc function in this context seems to be unrelated to its antioxidant activity, but it nevertheless seems likely that ROS contribute to the lower reprogramming efficiency of SKO compared to SKOM. The mechanism underlying this increase in ROS merits further investigation and suggests that metabolic changes are triggered differentially by SKO and SKOM. Besides reducing p53, Vc accelerates transcriptome changes during reprogramming and allows the conversion of pre-iPSCs to iPSCs. The extent to which these observations relate to cell senescence is unclear, and it is possible that Vc is acting in other ways as well. For example, it could accelerate stochastic events during reprogramming, perhaps by promoting epigenetic modifications that allow further changes to proceed. In this regard, Vc is a cofactor in reactions driven by dioxygenases including collagen prolyl hydroxylases, HIF (hypoxia-inducible factor) prolyl hydroxylases, and histone demethylases (Shi, 2007), and it is interesting to consider that Vc might influence reprogramming by increasing the activity of these enzymes. Histone demethylases are important for development and modulate the expression of the ESC master transcription factor Nanog (Cloos etal., 2008), so it is possible that Vc allows the reprogramming to run more smoothly by facilitating histone demethylation. While additional mechanistic studies are done, Vc may prove useful for high-throughput screening of compounds and siRNA oligos or for enhancing the efficiency of virus-free delivery systems (Kim etal., 2009,Yu etal., 2009). It is also an interesting concept that a vitamin with long-debated anti-aging effect (Harman, 1956,Massip etal., 2009) has such a potent effect on reprogramming, and our work may stimulate further research in this area as well.
- Somatic cells including fibroblasts quickly undergo senescence in culture, in part as a result of accumulation of reactive oxygen species (ROS) produced by cell metabolism (Parrinello etal., 2003). We studied ROS generation during the reprogramming of mouse embryonic fibroblasts (MEFs) and noticed a significant early increase (2.5- to 3-fold) in cells transduced with Sox2/Klf4/Oct4 (SKO) compared to SKOM and the control (Figure1A). This is consistent with SKO being less efficient than SKOM in generating iPSCs, and led us to hypothesize that antioxidants might improve the efficiency of SKO-based reprogramming by suppressing ROS. We found that a combination of vitamin B1 (Vb1), reduced gluthatione (GSH monoethyl ester, GMEE), sodium selenite (Sel), and ascorbic acid (vitamin C, or Vc) (Arrigoni and De Tullio, 2002) significantly accelerated the appearance of GFP+ cells in MEFs carrying a transgenic Oct4-GFP promoter and bypassed the need to split on feeders (Figure1B, left). We then measured the contribution of each antioxidant by using FACS and found that Vc accounted for the entire increase in reprogramming efficiency (Figure1B, middle), achievinga remarkable 10% of cells being GFP+ at day 16. Vb1, GMEE, Sel, and other compounds with compelling antioxidant activities including n-acetylcysteine, resveratrol, α-lipoic acid, vitamin E, and L-carnitine hydrochloride (not shown) did not have any noticeable effect. Vb1, GMEE, and Vc all reduced the steady-state ROS level in SKO-infected MEFs (Figure1B, right), suggesting that the activity of Vc in this context may in fact be independent of its antioxidant properties. Next, we evaluated the effect of splitting SKO-infected MEFs (3 103 cells) on feeders at day 7 postinfection, because under these circumstances GFP+ colonies originate from single cells. At day 20, most alkaline phosphatase-positive (AP+) colonies in wells treated with Vc were GFP+ compared to very few in the control (Figure1C), and the overall efficiency (number of colonies divided by number of starting cells) was 3.8%. iPSC clones generated with mixed antioxidants or Vc under these conditions were pluripotent as demonstrated by standard characterization procedures and the formation of teratomas and chimeric mice with contribution to the germline (Figure1D and Figures S1A S1H available online). Addition of Vc to SKO-infected adult mammary gland fibroblasts (MaFs) showed a similar increase in GFP+ cells compared to MEFs (FigureS1I), demonstrating that the effect of Vc is not restricted to a specific cell type. A dose response experiment in SKO-infected MEFs also showed that a low dose of Vc (10 g/ml) can achieve a maximum effect (Figure1E, left), suggesting that the enhanced reprogramming is not due to cell death or selection of resistant populations. Notably, Vc had a more potent effect in increasing GFP+ cells in SKO-infected MEFs than the widely used histone deacetylase inhibitor valproic acid (VPA) (Huangfu etal., 2008), and the combination of both was additive (Figure1E, middle), suggesting that they act through different mechanisms. Vc had to be added for the duration of the experiment to achieve its full potential (Figure1E, right). Consistently, DNA microarray analysis of an SKO time course experiment showed sustained acceleration of transcriptomic changes in the presence of Vc: Vc-treated cells at days 6, 8, and 10 clustered with day 10 untreated cells (FigureS1J).
- We then tested whether Vc can enhance reprogramming efficiency with SKOM. Mixed antioxidants promoted the appearance of GFP+ colonies by day 8 without splitting on feeders (Figure1F, left), compared to none in the control. FACS analysis was performed at day 9 to prevent cell overgrowth and detected an average 2% of GFP+ cells in Vc-treated cells while the other antioxidants had no effect (Figure1F, right). When SKOM-infected MEFs (2 103 cells) were split on feeders and allowed to grow until day 14, the corrected efficiency of AP+/GFP+ colony formation was 8.75% (Figure2G). Thus, Vc improves reprogramming efficiency with both SKO and SKOM, and the effect is not mediated, at least not exclusively, by a reduction in ROS.
Vitamin C Converts Pre-iPSCs into iPSCs
- Our observation that Vc increases the ratio of GFP+/AP+ colonies suggested that it may promote the transition from pre-iPSCs to iPSCs as described previously (Silva etal., 2008). To test this idea, we added mixed antioxidants or Vc to pre-iPSC clones derived from MEFs or MaFs and observed highly homogeneous acquisition of ESC-like characteristics and GFP fluorescence within the course of a few passages (Figures 2A and 2C). Newly reprogrammed iPSCs derived from pre-iPSCs were stable in continuous culture as evaluated by qPCR of pluripotent markers, demethylation of the Nanog proximal promoter, and formation of chimeric mice (Figures 2B and 2D 2F). Consistent with the rapid conversion to a pluripotent state, DNA microarray analysis showed quick prominent changes in gene expression in MaF pre-iPSCs treated with Vc (Figures S2A S2D). A summary of the iPSC cell lines generated from pre-iPSCs via Vc is included in FigureS2E.
- We also compared the ability of Vc and the two inhibitor cocktail 2i (ERK and GSK3β inhibitors) described by Silva etal., 2008 to transform pre-iPSCs into iPSCs. In standard mouse ESCs medium the percentage of GFP+ cells was higher in Vc-treated cells than in 2i-treated ones (Figure2G). In N2B27 plus LIF, the medium used in the original study, the percentage of GFP+ cells was similar for Vc and 2i but the proliferation potential was superior in Vc-treated cells (Figure2H). Moreover, western blot of lysates from pre-iPSCs treated with Vc did not show a reduction in total ERK or active ERK (pERK), although 2i eliminated the pERK signal as expected (Figure2I). Therefore, Vc efficiently transforms pre-iPSC clones into pluripotent iPSCs via a mechanism that seems different from 2i.
Vitamin C Alleviates the Senescence Roadblock during iPSC Generation
- We did not observe a significant change in apoptosis after Vc treatment of SKO- or SKOM-infected MEFs at any of the time points evaluated (Figure3A). However, we detected increased proliferation in the middle phase of reprogramming (Figure3B), suggesting a bypass of cell senescence. Supporting this idea, we had seen that nontransduced MEFs treated with Vc have a prolonged lifespan (up to 12 passages in this study) compared to control MEFs untreated or those treated with other antioxidants (Figures S3A and S3B). We then performed a western blot with lysates from an SKO time course experiment and observed a significant reduction in p53 and p21 levels in Vc-treated cells (Figure3C). The cells retained basal levels of p53, so the recruitment of Tp53BP1 to nuclear foci (indicative of functional DNA repair machinery) was unaffected by Vc in both SKO- and SKOM-infected MEFs (Figure3D). Next, we studied the effect of exogenous p53 activation or knockdown on Vc-mediated reprogramming. p53 adenoviruses or the p53-activating compound nutlin-3a inhibited the formation of GFP+ colonies in SKO-infected MEFs in a dose-dependent manner (Figure3E; FigureS3C). On the other hand, p53 shRNA increased GFP+ colonies by 100-fold without Vc and 2- to 3-fold with Vc (Figure3F). The latter modest increase might reflect the fact that Vc treatment alone reduces but does not abolish p53 expression, allowing the shRNA to reduce it further. Our data therefore suggest that Vc improves iPSC generation by reducing p53 levels and alleviating cell senescence while still maintaining an intact DNA repair machinery.
Vitamin C Improves the Generation of Human iPSCs
- Reprogramming is more challenging in human cells, raising a barrier for producing iPSCs and concerns about the quality and homogeneity of clones that do arise (Yamanaka, 2009). While our mouse experiments were in progress, we tested whether the antioxidant mix can also enhance reprogramming of human somatic cells. We used skin fibroblasts from a fetus with beta thalassemia, placental corionic mesenchymal cells (CMCs), and cells from the periosteal membrane. Addition of mixed antioxidants to KSR medium did not increase the basal low efficiency of reprogramming for any of these cell types (not shown), and we noticed that KSR already contains antioxidants including Vc (Garcia-Gonzalo and Izpisúa Belmonte, 2008). We then switched to a full serum protocol (Figure4A), previously thought to be ineffective for human cells, to mimic the culture conditions of our mouse experiments. Mixed antioxidants alone or in combination with VPA potently increased the number of AP+ ESC-like colonies in SKOM-infected cells (Figure4B). No increase was observed with SKO (not shown), possibly because of low efficacy of this combination in the human context (Nakagawa etal., 2008,Wernig etal., 2008). Once we had identified that Vc is the key compound in the antioxidant mix, we added Vc + VPA to a different set of human fibroblasts transduced with SKOM and observed very high reprogramming efficiency, up to 6.2% of the cells with fibroblasts from a patient with ornithine transcarbamylase deficiency (OTCD) (Figure4C). Vc or Vc + VPA could reprogram adipose stem cells (ASCs) with even higher efficiency (up to 7.06%), in agreement with a recent report describing superior susceptibility of these cells (Figure4D; Sun etal., 2009). Selected iPSC colonies from these experiments were expanded in KSR medium on feeder layers or in mTeSR medium on Matrigel. They homogeneously displayed features of human ESCs (hESCs) through multiple passages, as evaluated by morphology, number of chromosomes, activation of the endogenous ESC program, silencing of the transgenes, and demethylation of Oct4 and Nanog proximal promoters (Figures 4E 4H). Our iPSCs also acquired markers of all threegerm layers after differentiation into embryonic bodies (EBs) and developed complex teratomas (Figures 4I and 4J); a summary of human iPSCs characterization is shown in Figure4K.
For greater detail and to see the illustrations, graphs, graphics, etc. go to:
By Gabe Mirkin MD, January 11, 2010 — Dr. Paul Williams of the University of California at Berkeley thinks that the American Heart Association’s recommendation of “half an hour a day of exercise” is way too little. He has followed more than 100,000 runners for 20 years and has shown that exercising much more than that will dramatically reduce the
high incidence of heart attacks, strokes, certain cancers, glaucoma, diabetes, cataracts, macular degeneration, gout, gall stones, diverticulitis, and many other ailments (Medicine & Science in Sports & Exercise, March 2009). Dr. Williams found that running 40 miles per week can lower risk of stroke by 69 percent, heart attacks by 37 percent and diabetes by 68 percent. To prevent progressive weight gain with aging, the runners needed to add 1.4 miles a week each year.
How inactivity kills: Human muscles get their energy by
extracting sugar and fat from their blood supply. When muscles are
at rest, they need insulin for sugar to pass into their cells.
However, when muscles contract, sugar passes into their cells
without requiring insulin.
Extra fat blocks insulin receptors so insulin can’t do its
job of driving sugar into cells and blood sugar rises to high
levels. This causes sugar to stick to the surface of cell
membranes. Once stuck to cell membranes, sugar can never get
off and is eventually converted to sorbitol which destroys the cell
to cause all the terrible side effects of diabetes.
The extra sugar outside cells is converted to fat, which
blocks insulin receptors even more and prevents insulin from
doing its job, leading to more weight gain and eventually to
diabetes. Thirty-five percent of North Americans will become
diabetic because they exercise too little and eat too much.
Why more exercise is better: Contracting muscles remove
sugar rapidly from the bloodstream, without needing insulin, during
and for up to one hour after exercise. The effect tapers off to
zero at about 17 hours (American Journal of Clinical Nurtrition,
July 2008). You are protected maximally from high rises in blood
sugar and fat during and immediately after exercise. Therefore,
the more time you spend contracting muscles, the longer you will
be protected from the cell damage that leads to cancers, heart
attacks, strokes, and other consequences that shorten your life
or impair its quality.
firstname.lastname@example.org, January 11, 2010
Preoperative cleansing with chlorhexidine-alcohol (rather than povidone-iodine), and detecting and decolonizing Staphylococcus aureus nasal carriers, were each found to reduce the infection rate.
Several evidenced-based strategies for preventing surgical-site infections (SSIs) – for example, timely perioperative antibiotic use, clipping rather than shaving for hair removal, and maintaining normothermia – have been widely adopted. The jury remains out for other SSI-prevention issues, including the best preparations for preoperative skin antisepsis and the benefits of decolonizing Staphylococcus aureus nasal carriers. Two randomized, controlled, multicenter trials (both partially supported by industry) now shed light on these prevention approaches.
Investigators in the U.S. randomized 897 adults undergoing clean-contaminated surgery to preoperative skin preparation with chlorhexidine gluconate (CHG) and alcohol or with povidone-iodine (P-I) and assessed the occurrence of SSIs within 30 days postoperatively. In an intent-to-treat analysis, CHG-alcohol use was associated with a lower overall rate of SSIs (9.5% vs. 16.1% for P-I; P=0.004) and lower rates of superficial (4.2% vs. 8.6%; P=0.008) and deep (1.0% vs. 3.0%; P=0.05) incisional SSIs. No significant between-group differences were seen in rates of organ-space infections (4.4% and 4.6%, respectively) or sepsis from SSIs (2.7% and 4.3%).
Researchers in the Netherlands, using real-time PCR, screened 6771 newly admitted patients for S. aureus nasal carriage. Of the 1251 S. aureus carriers, 918 were randomized to receive 5 days of treatment with 2% mupirocin nasal ointment (twice daily) plus CHG soap (daily) or with placebo. The rate of healthcare-associated S. aureus infections was significantly lower in the mupirocin-CHG group than in the placebo group (3.4% vs. 7.7%; relative risk, 0.42; 95% confidence interval, 0.23-0.75). Most enrolled patients were surgical (88.1%), and most S. aureus infections were SSIs (81.6%). Among surgical patients, the rate of deep SSIs was lower in the mupirocin-CHG group (0.9% vs. 4.4%; RR, 0.21; 95% CI, 0.07-0.62).
Comment: CHG-alcohol, which is already preferred for skin preparation before intravascular catheter placement, should now replace P-I for preoperative skin antisepsis. The implications of the S. aureus decolonization study are less clear because the relative importance of the two topical therapies (nasal mupirocin and CHG soap) is unclear. Until we know whether screening and targeted decolonization is superior to preoperative bathing of all patients with CHG soap, this approach should be reserved for high-risk procedures (e.g., cardiac surgery, orthopedic implants). As an editorialist points out, interventions that can be applied to all patients and that target all organisms are preferred to organism-specific approaches that carry the added expense and logistical difficulty associated with identifying carriers before surgery.
Published in Journal Watch Infectious Diseases January 6, 2010
Darouiche RO et al. Chlorhexidine-alcohol versus povidone-iodine for surgical-site antisepsis. N Engl J Med 2010 Jan 7; 362:18.
Bode LGM et al. Preventing surgical-site infections in nasal carriers of Staphylococcus aureus. N Engl J Med 2010 Jan 7; 362:9.
Sepsis is a condition in which the body is fighting a severe infection that has spread via the bloodstream. If a patient becomes “septic,” they will likely be in a state of low blood pressure termed “shock.” This condition can develop either as a result of the body’s own defense system or from toxic substances made by the infecting agent (such as a bacteria, virus, or fungus).
People at risk for sepsis
- People whose immune systems (the body’s defense against microbes) are not functioning well because of an illness (such as cancer or AIDS) or because of medical treatments (such as chemotherapy for cancer or steroids for a number of medical conditions) that weaken the immune system are more prone to develop sepsis. It is important to remember that even healthy people can become septic.
- Because their immune systems are not completely developed, very young babies may get sepsis if they become infected and are not treated in a timely manner. Often, if they develop signs of an infection such as fever, infants have to receive antibiotics and be admitted to the hospital. Sepsis in the very young is often more difficult to diagnose because the typical signs of sepsis (fever, change in behavior) may not be present or may be more difficult to ascertain.
- The elderly population, especially those with other medical illnesses such as diabetes, may be at increased risk as well.
The number of people dying from sepsis has almost doubled in the past 20 years. This is most likely due to the increased number of patients who suffer from sepsis. The number of patients who develop sepsis has increased for many reasons:
- There has been a large increase in sepsis because doctors have started treating cancer patients and organ-transplant patients, among others, with strong medications that weaken the immune system. In the past, these patients would have died due to complications of their disease. As we get better at treating the underlying illness, patients survive longer but then sometimes die due to the complications of the therapy.
- Also, because of our aging population, the number of elderly people with weak immune systems has grown.
- Finally, because antibiotic use has increased, many strains of bacteria have become resistant to antibiotics, making the treatment of sepsis more difficult in some cases.
Many different microbes can cause sepsis. Although bacteria are most commonly the cause, viruses and fungi can also cause sepsis. Infections in the lungs (pneumonia), bladder and kidneys (urinary tract infections), skin (cellulitis), abdomen (such as appendicitis), and other areas (such as meningitis) can spread and lead to sepsis. Infections that develop after surgery can also lead to sepsis.
Who is at risk for sepsis?
- Very young people and elderly people
- Anyone who is taking immunosuppressive medications (such as transplant recipients)
- People who are being treated with chemotherapy drugs or radiation
- People who have no spleen (the spleen helps fight certain infections)
- People taking steroids (especially over the long term)
- People with long-standing diabetes, AIDS, or cirrhosis
- Someone who has very large burns or severe injuries
- People with infections such as the following
- Urinary tract infection
- Ruptured appendix
Sepsis Symptoms and Signs
- If a person has sepsis, they often will have fever. Sometimes, though, the body temperature may be normal or even low.
- The individual may also have chills and severe shaking.
- The heart may be beating very fast, and breathing may be rapid. Low blood pressure is often observed in septic patients.
- Confusion, disorientation, and agitation may be seen as well as dizziness and decreased urination.
- Some patients who have sepsis develop a rash on their skin. The rash may be a reddish discoloration or small dark red dots throughout the body.
- You may also develop pain in the joints at your wrists, elbows, back, hips, knees, and ankles.
When to Seek Medical Care
When to call the doctor
A person should call the doctor if they or a loved one has signs and symptoms of sepsis. If any of the following are true about the patient’s medical history, they need to be especially vigilant regarding possible sepsis symptoms if the person
- is being treated with chemotherapy or radiation,
- has had an organ transplant,
- has diabetes,
- has AIDS.
When to go to the hospital
- If a child younger than 2 months of age has fever, lethargy, poor feeding, a change in normal behavior, or an unusual rash, call the doctor and proceed to the hospital.
- If you have a family member with confusion, dizziness, fast heartbeat, fast breathing, fever, chills, rash, or dizziness, call your doctor immediately or go to the hospital’s emergency department.
Exams and Tests
In the hospital, the doctor may conduct various tests.
- Blood work may be done by inserting a needle into a vein in the patient’s hand or arm and drawing blood into several tubes. This blood may be analyzed to see if the patient has an elevation in the white blood counts.
- Blood may also be sent to the lab to be placed on a medium where bacteria will grow if they are present in the blood. This is called a blood culture. Results from this test usually take over 24 hours. Lab technicians may also look for bacteria in the blood under the microscope on slides.
- Samples may be taken of sputum (mucus), urine, spinal fluid, or abscess contents to look for the presence of infectious organisms.
- To obtain clean urine and to measure the amount of urine being produced, a flexible rubber tube may be placed into the bladder (catheter).
- Spinal fluid may be obtained from the lower back (spinal tap). After the skin is cleaned and numbed, a hollow needle is placed between the bones of the spine into the canal containing the spinal cord. Because the needle is placed lower than where the cord ends, there is little danger of injuring the nerves of the spinal cord. When the needle is in the correct spot, the doctor will let the fluid drip into tubes. The sample of fluid are sent to the lab for testing.
- Other tests may include a chest X-ray to look for pneumonia or a CT scan to see if there is infection in the abdomen.
- A dye might be injected into a vein during a CT scan to help highlight certain organs in the abdomen. During the injection of this dye, the patient may feel a flushing or hot sensation or even become nauseated, but this feeling will last only a very short time.
- The CT scan is a series of X-rays taken from different angles very quickly and put together by the computer to show an image of the internal organs.
- Usually, a radiologist reads the results and notifies the patient’s doctor.
- In the hospital, the patient may be placed on a cardiac monitor, which will show the patient’s heart rate and rhythm.
- If the patient is an young child who is ill and being evaluated for sepsis, he or she will get similar tests and treatment.
Sepsis is a medical emergency. If a person has sepsis, treatment is usually given in the hospital and often in an intensive care unit.
- The patient will likely be placed on oxygen, either by a tube that is placed near the nose or through a clear plastic mask.
- Depending on the results of the tests, the doctor may order medications. These medications may include antibiotics given by IV (given directly into the vein). Initially, the antibiotics may be those that kill many different bacteria because the exact kind of infection the patient has is not known. Once the blood culture results show the identity of the bacteria, your doctor may select a different antibiotic that kills the specific microbe.
- The doctor may also order IV salt solution (saline) and medications to increase the blood pressure if it is too low.
- The doctor will likely admit the patient to the hospital at least until the blood culture results are known. If the patient is very ill and with low blood pressure, the doctor may admit the patient to the intensive care unit (ICU) and may consult other doctors to help in the management of the illness.
- If results show an infection in the abdomen, either drainage of the infection by tubes or surgery may be necessary.
- Research to discover new treatments for sepsis has failed over the past 20-30 years. Many medications that were thought to be helpful were proven to have no benefit in clinical trials. However, scientists are working diligently to discover medications that will modify the body’s aggressive immune response to microbes, which leads to sepsis.
The prognosis of sepsis depends on age, previous health history, overall health status, how quickly the diagnosis is made, and the type of organism causing the sepsis.
- For elderly people with many illnesses or for those whose immune system is not working well because of illness or certain medications and sepsis is advanced, the death rate may be as high as 80%.
- On the other hand, for healthy people with no prior illness, the death rate may be low, at around 5%.
- The overall death rate from sepsis is approximately 40%. It is important to remember that the prognosis also depends on any delay in diagnosis and treatment. The earlier the treatment is started, the better the outcome will be.
Pictures of Sepsis
Media type: Photo
Media type: Photo
Synonyms and Keywords
Classification and external resources
|ICD–10||A40. – A41.0|
Sepsis is a serious medical condition that is characterized by a whole-body inflammatory state (called a systemic inflammatory response syndrome or SIRS) and the presence of a known or suspected infection. The body may develop this inflammatory response to microbes in the blood, urine, lungs, skin, or other tissues. An incorrect layman’s term for sepsis is blood poisoning, more aptly applied to Septicemia, below.
Septicemia (also septicaemia or septicæmia [sep⋅ti⋅cæ⋅mi⋅a] or erroneously Septasemia and Septisema) is a related but deprecated (formerly sanctioned) medical term referring to the presence of pathogenic organisms in the blood-stream, leading to sepsis. The term has not been sharply defined. It has been inconsistently used in the past by medical professionals, for example as a synonym of bacteremia, causing some confusion. The present medical consensus is therefore that the term “septicemia” is problematic and should be avoided.
Sepsis is usually treated in the intensive care unit with intravenous fluids and antibiotics. If fluid replacement is insufficient to maintain blood pressure, specific vasopressor drugs can be used. Artificial ventilation and dialysis may be needed to support the function of the lungs and kidneys, respectively. To guide therapy, a central venous catheter and an arterial catheter may be placed. Sepsis patients require preventive measures for deep vein thrombosis, stress ulcers and pressure ulcers, unless other conditions prevent this. Some patients might benefit from tight control of blood sugar levels with insulin (targeting stress hyperglycemia), low-dose corticosteroids or activated drotrecogin alfa (recombinant protein C).
Severe sepsis occurs when sepsis leads to organ dysfunction, low blood pressure (hypotension), or insufficient blood flow (hypoperfusion) to one or more organs (causing, for example, lactic acidosis, decreased urine production, or altered mental status). Sepsis can lead to septic shock, multiple organ dysfunction syndrome (formerly known as multiple organ failure), and death. Organ dysfunction results from sepsis-induced hypotension (< 90 mmHg or a reduction of ≥ 40 mmHg from baseline) and diffuse intravascular coagulation, among other things.
Bacteremia is the presence of viable bacteria in the bloodstream. Likewise, the terms viremia and fungemia simply refer to viruses and fungi in the bloodstream. These terms say nothing about the consequences this has on the body. For example, bacteria can be introduced into the bloodstream during toothbrushing. This form of bacteremia almost never causes problems in normal individuals. However, bacteremia associated with certain dental procedures can cause bacterial infection of the heart valves (known as endocarditis) in high-risk patients. Conversely, a systemic inflammatory response syndrome can occur in patients without the presence of infection, for example in those with burns, polytrauma, or the initial state in pancreatitis and chemical pneumonitis.
In the United States, sepsis is the second-leading cause of death in non-coronary ICU patients, and the tenth-most-common cause of death overall according to data from the Centers for Disease Control and Prevention (the first being multiple organ dysfunction syndrome). Sepsis is common and also more dangerous in elderly, immunocompromised, and critically-ill patients. It occurs in 1-2% of all hospitalizations and accounts for as much as 25% of intensive-care unit (ICU) bed utilization. It is a major cause of death in intensive-care units worldwide, with mortality rates that range from 20% for sepsis to 40% for severe sepsis to >60% for septic shock.
Signs and symptoms
In addition to symptoms related to the provoking infection, sepsis is characterized by evidence of acute inflammation present throughout the entire body, and is, therefore, frequently associated with fever and elevated white blood cell count (leukocytosis) or low white blood cell count and lower-than-average temperature, and vomiting. The modern concept of sepsis is that the host’s immune response to the infection causes most of the symptoms of sepsis, resulting in hemodynamic consequences and damage to organs. This host response has been termed systemic inflammatory response syndrome (SIRS) and is characterized by hemodynamic compromise and resultant metabolic derangement. Outward physical symptoms of this response frequently include a high heart rate (above 100 beats per minute), high respiratory rate (above 20 breaths per minute), elevated WBC count (above 12,000) and elevated or lowered body temperature (under 36 °C or over 38 °C). Sepsis is differentiated from SIRS by the presence of a known pathogen. For example SIRS and a positive blood culture for a pathogen indicates the presence of sepsis. Without a known infection you can not classify the above symptoms as sepsis, only SIRS.
This immunological response causes widespread activation of acute-phase proteins, affecting the complement system and the coagulation pathways, which then cause damage to the vasculature as well as to the organs. Various neuroendocrine counter-regulatory systems are then activated as well, often compounding the problem. Even with immediate and aggressive treatment, this may progress to multiple organ dysfunction syndrome and eventually death.
According to the American College of Chest Physicians and the Society of Critical Care Medicine, there are different levels of sepsis:
- Systemic inflammatory response syndrome (SIRS). Defined by the presence of two or more of the following findings:
- Body temperature < 36 °C (97 °F) or > 38 °C (100 °F) (hypothermia or fever).
- Heart rate > 100 beats per minute (tachycardia).
- Respiratory rate > 20 breaths per minute or, on blood gas, a PaCO2 less than 32 mm Hg (4.3 kPa) (tachypnea or hypocapnia due to hyperventilation).
- White blood cell count < 4,000 cells/mm3 or > 12,000 cells/mm3 (< 4 × 109 or > 12 × 109 cells/L), or greater than 10% band forms (immature white blood cells). (leukopenia, leukocytosis, or bandemia).
- Sepsis. Defined as SIRS in response to a confirmed infectious process. Infection can be suspected or proven (by culture, stain, or polymerase chain reaction (PCR)), or a clinical syndrome pathognomonic for infection. Specific evidence for infection includes WBCs in normally sterile fluid (such as urine or cerebrospinal fluid (CSF), evidence of a perforated viscus (free air on abdominal x-ray or CT scan, signs of acute peritonitis), abnormal chest x-ray (CXR) consistent with pneumonia (with focal opacification), or petechiae, purpura, or purpura fulminans
- Severe sepsis. Defined as sepsis with organ dysfunction, hypoperfusion, or hypotension.
- Septic shock. Defined as sepsis with refractory arterial hypotension or hypoperfusion abnormalities in spite of adequate fluid resuscitation. Signs of systemic hypoperfusion may be either end-organ dysfunction or serum lactate greater than 4 mmol/dL. Other signs include oliguria and altered mental status. Patients are defined as having septic shock if they have sepsis plus hypotension after aggressive fluid resuscitation (typically upwards of 6 liters or 40 ml/kg of crystalloid).
Examples of end-organ dysfunction include the following:
- multifocal necrotizing leukoencephalopathy
More specific definitions of end-organ dysfunction exist for SIRS in pediatrics.
- Cardiovascular dysfunction (after fluid resuscitation with at least 40 ml/kg of crystalloid)
- hypotension with blood pressure < 5th percentile for age or systolic blood pressure < 2 standard deviations below normal for age, OR
- vasopressor requirement, OR
- two of the following criteria:
- Respiratory dysfunction (in the absence of cyanotic heart disease or known chronic lung disease)
- the ratio of the arterial partial-pressure of oxygen to the fraction of oxygen in the gases inspired (PaO2/FiO2) < 300 (the definition of acute lung injury), OR
- arterial partial-pressure of carbon dioxide (PaCO2) > 65 torr (20 mmHg) over baseline PaCO2 (evidence of hypercapnic respiratory failure), OR
- supplemental oxygen requirement of greater than FiO2 0.5 to maintain oxygen saturation ≥ 92%
- Neurologic dysfunction
- Hematologic dysfunction
- Renal dysfunction
- Hepatic dysfunction (only applicable to infants > 1 month)
Consensus definitions, however, continue to evolve, with the latest expanding the list of signs and symptoms of sepsis to reflect clinical bedside experience.
In common clinical usage, sepsis specifically refers to the presence of a serious bacterial infection (SBI) (such as meningitis, pneumonia, pyelonephritis, or gastroenteritis) in the setting of fever. Criteria with regards to hemodynamic compromise or respiratory failure are not useful clinically because these symptoms often do not arise in neonates until death is imminent and unpreventable.
Adults and children
The therapy of sepsis rests on antibiotics, surgical drainage of infected fluid collections, fluid replacement and appropriate support for organ dysfunction. This may include hemodialysis in kidney failure, mechanical ventilation in pulmonary dysfunction, transfusion of blood products, and drug and fluid therapy for circulatory failure. Ensuring adequate nutrition-preferably by enteral feeding, but if necessary by parenteral nutrition-is important during prolonged illness.
A problem in the adequate management of septic patients has been the delay in administering therapy after sepsis has been recognized. Published studies have demonstrated that for every hour delay in the administration of appropriate antibiotic therapy there is an associated 7% rise in mortality. A large international collaboration was established to educate people about sepsis and to improve patient outcomes with sepsis, entitled the “Surviving Sepsis Campaign.” The Campaign has published an evidence-based review of management strategies for severe sepsis, with the aim to publish a complete set of guidelines in subsequent years.
Early Goal Directed Therapy (EGDT), developed at Henry Ford Hospital by E. Rivers, MD, is a systematic approach to resuscitation that has been validated in the treatment of severe sepsis and septic shock. It is meant to be started in the Emergency Department. The theory is that one should use a step-wise approach, having the patient meet physiologic goals, to optimize cardiac preload, afterload, and contractility, thus optimizing oxygen delivery to the tissues. A recent meta-analysis showed that EGDT provides a benefit on mortality in patients with sepsis. As of December 2008 some controversy around its uses remains and a number of trials are ongoing in an attempt to resolve this.
In EGDT, fluids are administered until the central venous pressure (CVP), as measured by a central venous catheter, reaches 8-12 cm of water (or 10-15 cm of water in mechanically ventilated patients). Rapid administration of several liters of isotonic crystalloid solution is usually required to achieve this. If the mean arterial pressure is less than 65 mmHg or greater than 90 mmHg, vasopressors or vasodilators are given as needed to reach the goal. Once these goals are met, the mixed venous oxygen saturation (SvO2), i.e., the oxygen saturation of venous blood as it returns to the heart as measured at the vena cava, is optimized. If the SvO2 is less than 70%, blood is given to reach a hemoglobin of 10 g/dl and then inotropes are added until the SvO2 is optimized. Elective intubation may be performed to reduce oxygen demand if the SvO2 remains low despite optimization of hemodynamics. Urine output is also monitored, with a minimum goal of 0.5 ml/kg/h. In the original trial, mortality was cut from 46.5% in the control group to 30.5% in the intervention group. The Surviving Sepsis Campaign guidelines recommend EGDT for the initial resuscitation of the septic patient with a level B strength of evidence (single randomized control trial).
Most therapies aimed at the inflammation process itself have failed to improve outcome, however drotrecogin alfa (activated protein C, one of the coagulation factors) has been shown to decrease mortality from about 31% to about 25% in severe sepsis. To qualify for drotrecogin alfa, a patient must have severe sepsis or septic shock with an APACHE II score of 25 or greater and a low risk of bleeding.
During critical illness, a state of adrenal insufficiency and tissue resistance (the word ‘relative’ resistance should be avoided) to corticosteroids may occur. This has been termed critical illness-related corticosteroid insufficiency. Treatment with corticosteroids might be most beneficial in those with septic shock and early severe acute respiratory distress syndrome (ARDS), whereas its role in other patients such as those with pancreatitis or severe pneumonia is unclear. These recommendations stem from studies showing benefits from low dose hydrocortisone treatment for septic shock patients and methylprednisolone in ARDS patients. However, the exact way of determining corticosteroid insufficiency remains problematic. It should be suspected in those poorly responding to resuscitation with fluids and vasopressors. ACTH stimulation testing is not recommended to confirm the diagnosis. Glucocorticoid drugs should be weaned and not stopped abruptly.
In some cases, sepsis may lead to inadequate tissue perfusion and necrosis. As this may affect the extremities, amputation may become necessary. On January 8 2009 a patent request was submitted for the possible treatment of sepsis ( 20090011974 Scavenger Receptor B1 (Cla-1) Targeting for the Treatment of Infection, Sepsis and Inflammation 01-08-2009) .
Note that, in neonates, sepsis is difficult to diagnose clinically. They may be relatively asymptomatic until hemodynamic and respiratory collapse is imminent, so, if there is even a remote suspicion of sepsis, they are frequently treated with antibiotics empirically until cultures are sufficiently proven to be negative.
Prognosis can be estimated with the MEDS score. Approximately 20-35% of patients with severe sepsis and 40-60% of patients with septic shock die within 30 days. Others die within the ensuing 6 months. Late deaths often result from poorly controlled infection, immunosuppression, complications of intensive care, failure of multiple organs, or the patient’s underlying disease.
Prognostic stratification systems such as APACHE II indicate that factoring in the patient’s age, underlying condition, and various physiologic variables can yield estimates of the risk of dying of severe sepsis. Of the individual covariates, the severity of underlying disease most strongly influences the risk of dying. Septic shock is also a strong predictor of short- and long-term mortality. Case-fatality rates are similar for culture-positive and culture-negative severe sepsis.
Some patients may experience severe long term cognitive decline following an episode of severe sepsis, but the absence of baseline neuropsychological data in most sepsis patients makes the incidence of this difficult to quantify or to study. A preliminary study of nine patients with septic shock showed abnormalities in seven patients by MRI.
The blood of the Vikings is still coursing through the veins of men living in the North West of England — according to a new study. (Credit: iStockphoto/Manuel Velasco)
The University of Nottingham – The blood of the Vikings is still coursing through the veins of men living in the North West of England – according to a new study.
Focusing on the Wirral in Merseyside and West Lancashire the study of 100 men, whose surnames were in existence as far back as medieval times, has revealed that 50 per cent of their DNA is specifically linked to Scandinavian ancestry.
The collaborative study, by The University of Nottingham, the University of Leicester and University College London, reveals that the population in parts of northwest England carries up to 50 per cent male Norse origins, about the same as modern Orkney.
Stephen Harding, Professor of Physical Biochemistry in the School of Biosciences said; “DNA on the male Y-chromosome is passed along the paternal line from generation to generation with very little change, providing a powerful probe into ancestry. So a man’s Y-chromosome type is a marker to his paternal past. The method is most powerful when populations rather than individuals are compared with each other. We can also take advantage of the fact that surnames are also passed along the paternal generations. Using tax and other records the team selected volunteers who possess a surname present in the region prior to 1600. This gets round the problems of large population movements that have occurred since the Industrial revolution in places like Merseyside.”
After their expulsion from Dublin in 902AD the Wirral Vikings, initially led by the Norwegian Viking INGIMUND, landed in their boats along the north Wirral coastline. Place names still reflect the North West’s Viking past. Aigburth, Formby, Crosby, Toxteth, Croxteth are all Viking names – even the football team Tranmere is Viking. Thingwall is the name of a Viking parliament or assembly (Thingvellir in Iceland) and the only two in England are both in the North West – one in Wirral and one in Liverpool.
The results of this research have just been published by Molecular Biology and Evolution. The 14-strong research team, funded by the Wellcome Trust and a Watson-Crick DNA anniversary award from the Biotechnology and Biological Sciences Research Council (BBSRC), was led by the University of Nottingham’s Professor Stephen Harding and Professor Judith Jesch and the University of Leicester’s Professor Mark Jobling.
Story Source: Adapted from materials provided by University of Nottingham.
Thomas Jefferson said in 1802
‘I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around the banks will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered..’
The Museum of American Finance hosts “Did Economists Get It Wrong?” – an expert panel on the different explanations of the current crisis on the 80th anniversary of the Crash of 1929.
David Adler, Economic journalist and author of Snap Judgment (Financial Times Press, 2009)
Justin Fox, Economics and business columnist for Time magazine
Teresa Ghilarducci, Irene and Bernard L. Schwartz Professor in Economic Policy Analysis at the New School for Social Research and the Director of the Schwartz Center for Economic Policy Analysis (SCEPA)
Robert Shiller, Arthur M. Okun Professor of Economics, Department of Economics and Cowles Foundation for Research in Economics, Yale University, and Professor of Finance and Fellow at the International Center for Finance, Yale School of Management
About the Museum of American Finance
The Museum of American Finance, an affiliate of the Smithsonian Institution, is the nation’s only public museum dedicated to finance, entrepreneurship and the open market system. With its extensive collection of financial documents and objects, its seminars and educational programming, its publication and oral history program, the Museum portrays the breadth and richness of American financial and economic history. For more information, visit www.moaf.org. To contribute to the Museum’s Recessipedia wiki on the current financial crisis, please visit www.recessipedia.org.