Biomarkers of Necrotizing Enterocolitis: The Search Continues.

Necrotizing enterocolitis (NEC) is the most common gastrointestinal (GI) emergency in the neonatal intensive care unit. Despite advances in medical care, mortality and morbidity from NEC have not changed. This is likely due to the lack of a clear understanding of this multifactorial disease, and reliable biomarkers for accurate diagnosis of NEC. Currently, the diagnosis of NEC is made by a combination of nonspecific clinical signs, symptoms, and radiological findings. Though biomarkers have been studied extensively, none offer an acceptable sensitivity or specificity to be used. This review will focus on the available literature on biomarkers for preterm NEC, acknowledging the limitations in studies including the variability of inclusion criteria, and most importantly, the lack of gold standard case definition for NEC.

Extending the range of additivity in using inclusive fitness.

Inclusive fitness is a concept widely utilized by social biologists as the quantity organisms appear designed to maximize. However, inclusive fitness theory has long been criticized on the (uncontested) grounds that other quantities, such as offspring number, predict gene frequency changes accurately in a wider range of mathematical models. Here, we articulate a set of modeling assumptions that extend the range of scenarios in which inclusive fitness can be applied. We reanalyze recent formal analyses that searched for, but did not find, inclusive fitness maximization. We show (a) that previous models have not used Hamilton's definition of inclusive fitness, (b) a reinterpretation of Hamilton's definition that makes it usable in this context, and (c) that under the assumption of probabilistic mixing of phenotypes, inclusive fitness is indeed maximized in these models. We also show how to understand mathematically, and at an individual level, the definition of inclusive fitness, in an explicit population genetic model in which exact additivity is not assumed. We hope that in articulating these modeling assumptions and providing formal support for inclusive fitness maximization, we help bridge the gap between empiricists and theoreticians, which in some ways has been widening, demonstrating to mathematicians why biologists are content to use inclusive fitness, and offering one way to utilize inclusive fitness in general models of social behavior.

Tracking Antimicrobial Resistance Determinants in Diarrheal Pathogens: A Cross-Institutional Pilot Study.

Infectious diarrhea affects over four billion individuals annually and causes over a million deaths each year. Though not typically prescribed for treatment of uncomplicated diarrheal disease, antimicrobials serve as a critical part of the armamentarium used to treat severe or persistent cases. Due to widespread over- and misuse of antimicrobials, there has been an alarming increase in global resistance, for which a standardized methodology for geographic surveillance would be highly beneficial. To demonstrate that a standardized methodology could be used to provide molecular surveillance of antimicrobial resistance (AMR) genes, we initiated a pilot study to test 130 diarrheal pathogens (Campylobacter spp., Escherichia coli, Salmonella, and Shigella spp.) from the USA, Peru, Egypt, Cambodia, and Kenya for the presence/absence of over 200 AMR determinants. We detected a total of 55 different determinants conferring resistance to ten different categories of antimicrobials: genes detected in ≥ 25 samples included blaTEM, tet(A), tet(B), mac(A), mac(B), aadA1/A2, strA, strB, sul1, sul2, qacEΔ1, cmr, and dfrA1. The number of determinants per strain ranged from none (several Campylobacter spp. strains) to sixteen, with isolates from Egypt harboring a wider variety and greater number of genes per isolate than other sites. Two samples harbored carbapenemase genes, blaOXA-48 or blaNDM. Genes conferring resistance to azithromycin (ere(A), mph(A)/mph(K), erm(B)), a first-line therapeutic for severe diarrhea, were detected in over 10% of all Enterobacteriaceae tested: these included >25% of the Enterobacteriaceae from Egypt and Kenya. Forty-six percent of the Egyptian Enterobacteriaceae harbored genes encoding CTX-M-1 or CTX-M-9 families of extended-spectrum ß-lactamases. Overall, the data provide cross-comparable resistome information to establish regional trends in support of international surveillance activities and potentially guide geospatially informed medical care.

The social coevolution hypothesis for the origin of enzymatic cooperation.

At the start of life, the origin of a primitive genome required individual replicators, or genes, to act like enzymes and cooperatively copy each other. The evolutionary stability of such enzymatic cooperation poses a problem, because it would have been susceptible to parasitic replicators that did not act like enzymes but could still benefit from the enzymatic behaviour of other replicators. Existing hypotheses to solve this problem require restrictive assumptions that may not be justified, such as the evolution of a cell membrane before the evolution of enzymatic cooperation. We show theoretically that, instead, selection itself can lead to replicators grouping themselves together in a way that favours cooperation. We show that the tendency to physically associate with others and cooperative enzymatic activity can coevolve, leading to the evolution of physically linked cooperative replicators. Our results shift the empirical problem from a search for special environmental conditions to questions about what types of phenotypes can be produced by simple replicators.

Honest signaling and the double counting of inclusive fitness.

Inclusive fitness requires a careful accounting of all the fitness effects of a particular behavior. Verbal arguments can potentially exaggerate the inclusive fitness consequences of a behavior by including the fitness of relatives that was not caused by that behavior, leading to error. We show how this "double-counting" error can arise, with a recent example from the signaling literature. In particular, we examine the recent debate over whether parental divorce increases parent-offspring conflict, selecting for less honest signaling. We found that, when all the inclusive fitness consequences are accounted for, parental divorce increases conflict between siblings, in a way that they can select for less honest signaling. This prediction is consistent with the empirical data. More generally, our results illustrate how verbal arguments can be misleading, emphasizing the advantage of formal mathematical models.

Managing Ideas, People, and Projects: Organizational Tools and Strategies for Researchers.

Primary Investigators at all levels of their career face a range of challenges related to optimizing their activity within the constraints of deadlines and productive research. These range from enhancing creative thought and keeping track of ideas to organizing and prioritizing the activity of the members of the group. Numerous tools now exist that facilitate the storage and retrieval of information necessary for running a laboratory to advance specific project goals within associated timelines. Here we discuss strategies and tools/software that, together or individually, can be used as is or adapted to any size scientific laboratory. Specific software products, suggested use cases, and examples are shown across the life cycle from idea to publication. Strategies for managing the organization of, and access to, digital information and planning structures can greatly facilitate the efficiency and impact of an active scientific enterprise. The principles and workflow described here are applicable to many different fields.

ABO blood group and procoagulant factors: the hypercoagulation hypothesis ABO and Procoagulant Factors.

BACKGROUND: The correlation between procoagulant levels-factor VIII (FVIII), von Willebrand factor (vWF), and fibrinogen-and risk of thrombosis has been well documented in adult populations. We hypothesize that interaction of passively transferred isoagglutinins in premature neonates with a compromised immune system may trigger an immune response that can target the immature gastrointestinal tract. The objective of this study is to evaluate if there are procoagulant level differences in preterm newborns stratified by ABO blood group. METHODS: VWF, FVIII, and fibrinogen levels were analyzed in neonates ≤32 weeks and/or birthweight ≤1500 g over the first 6 weeks of life. Demographic, blood type, and transfusion data were collected. RESULTS: Elevations in vWF and FVIII were found to be statistically significant in the third week of life in non-O neonates vs. type O neonates. FVIII was also found to be significantly elevated in week 1. Transfused neonates also showed elevations between weeks 0 and 3. CONCLUSION: There appears to be a time-dependent variation in procoagulant factor levels in preterm newborns. Although the clinical significance remains unclear, prothrombotic factors vWF and FVIII are significantly higher in non-O blood-type preterm neonates in the third week of life.

Inclusive fitness is an indispensable approximation for understanding organismal design.

For some decades most biologists interested in design have agreed that natural selection leads to organisms acting as if they are maximizing a quantity known as "inclusive fitness." This maximization principle has been criticized on the (uncontested) grounds that other quantities, such as offspring number, predict gene frequency changes accurately in a wider range of mathematical models. Here, we adopt a resolution offered by Birch, who accepts the technical difficulties of establishing inclusive fitness maximization in a fully general model, while concluding that inclusive fitness is still useful as an organizing framework. We set out in more detail why inclusive fitness is such a practical and powerful framework, and provide verbal and conceptual arguments for why social biology would be more or less impossible without it. We aim to help mathematicians understand why social biologists are content to use inclusive fitness despite its theoretical weaknesses. Here, we also offer biologists practical advice for avoiding potential pitfalls.

Kin Selection in the RNA World.

Various steps in the RNA world required cooperation. Why did life's first inhabitants, from polymerases to synthetases, cooperate? We develop kin selection models of the RNA world to answer these questions. We develop a very simple model of RNA cooperation and then elaborate it to model three relevant issues in RNA biology: (1) whether cooperative RNAs receive the benefits of cooperation; (2) the scale of competition in RNA populations; and (3) explicit replicator diffusion and survival. We show: (1) that RNAs are likely to express partial cooperation; (2) that RNAs will need mechanisms for overcoming local competition; and (3) in a specific example of RNA cooperation, persistence after replication and offspring diffusion allow for cooperation to overcome competition. More generally, we show how kin selection can unify previously disparate answers to the question of RNA world cooperation.

The evolution of cooperation in simple molecular replicators.

In order for the first genomes to evolve, independent replicators had to act cooperatively, with some reducing their own replication rate to help copy others. It has been argued that limited diffusion explains this early cooperation. However, social evolution models have shown that limited diffusion on its own often does not favour cooperation. Here we model early replicators using social evolution tools. We show that: (i) replicators can be considered to be cooperating as a result of kin selection; (ii) limited diffusion on its own does not favour cooperation; and (iii) the addition of overlapping generations, probably a general trait of molecular replicators, promotes cooperation. These results suggest key life-history features in the evolution of the genome and that the same factors can favour cooperation across the entire tree of life.

The impact of household hygiene on the risk of bacterial diarrhea among Egyptian children in rural areas, 2004-2007.

INTRODUCTION: The present study, conducted between January 2004 and April 2007, explored the impact of household hygiene on the risk of bacterial diarrhea, using data from a prospective birth cohort of 348 infants in five villages in the Nile Delta in Egypt. METHODOLOGY: Neonates were enrolled at birth and followed up until 24 months of age. Children were visited twice a week to survey them for acute diarrhea. A detailed observational household hygiene survey was completed in-house every six months. Adjusted relative risk (aRR) of developing bacterial diarrhea was calculated for exposure to different hygiene variables and examined for specific bacterial pathogens. RESULTS: Exclusive breastfeeding reduced the risk of bacterial diarrhea by 70%, while bacterial diarrhea cases were 2.6 times higher in the warm season. Risk of Campylobacter diarrhea increased with the absence of barriers to keep birds and animals out of the eating area, the presence of garbage containers and a bathing facility within the compound, and the presence of feces on the floor of the bathing facility. Use of municipal water for drinking and cooking was associated with a lower risk of Campylobacter diarrhea. Risk of enterotoxigenic Escherichia coli diarrhea increased with uncovered garbage containers and the presence of liquid materials in the garbage containers, but decreased with the use of tap water in the washing facility. CONCLUSION: The results highlight some potential targets for interventions, such as expanding municipal water supply to all houses and comprehensive mass-media awareness programs to change hygiene-promoting behaviors and practices.

Influence of emotional expression, loudness, and gender on the acoustic parameters of vibrato in classical singers.

OBJECTIVES: Vibrato is considered one of the most essential characteristics of the classical singing voice. Vibrato can be acoustically described by the rate, extent, onset, and regularity. The aim of this study was to determine the influence of emotional expression on acoustic parameters of vibrato in classically trained singers. STUDY DESIGN: A prospective cohort study was performed. METHODS: Thirty healthy classical singers were recruited for this study, 29 singers met inclusion criteria. Inclusion criteria for this study were as follow: 1) no history of vocal pathology in the past year, 2) to have at least 5 years of classical singing training. Each subject was asked to sing the phrase "I Love You," while expressing four different emotions (tenderness, anger, happiness, and sadness) and without emotion (neutral state). The musical tonality of the phrase was adapted to each singer's vocal classification. Subjects were also recorded at three levels of loudness (pianissimo, mezzo forte, and fortissimo), while expressing each emotion. Acoustical analysis was performed during the vowel /o/ of the word "Love" to determine rate of vibrato, the extent of vibrato, and vibrato jitter. RESULTS: Vibrato parameters did not vary significantly when different emotions were expressed. However, vibrato jitter and extent did vary significantly between different levels of loudness. Significant differences were also noted in both rate and extent of vibrato when compared between sexes. CONCLUSIONS: Expression of emotions does not affect the acoustic parameters of vibrato, although some parameters are affected by loudness and gender.

Polymorphic variation in TIRAP is not associated with susceptibility to childhood TB but may determine susceptibility to TBM in some ethnic groups.

Host recognition of mycobacterial surface molecules occurs through toll like receptors (TLR) 2 and 6. The adaptor protein TIRAP mediates down stream signalling of TLR2 and 4, and polymorphisms in the TIRAP gene (TIRAP) have been associated with susceptibility and resistance to tuberculosis (TB) in adults. In order to investigate the role of polymorphic variation in TIRAP in childhood TB in South Africa, which has one of the highest TB incidence rates in the world, we screened the entire open reading frame of TIRAP for sequence variation in two cohorts of childhood TB from different ethnic groups (Xhosa and mixed ancestry). We identified 13 SNPs, including seven previously unreported, in the two cohorts, and found significant differences in frequency of the variants between the two ethnic groups. No differences in frequency between individual SNPs or combinations were found between TB cases and controls in either cohort. However the 558C-->T SNP previously associated with TB meningitis (TBM) in a Vietnamese population was found to be associated with TBM in the mixed ancestry group. Polymorphisms in TIRAP do not appear to be involved in childhood TB susceptibility in South Africa, but may play a role in determining occurrence of TBM.

Redo midurethral synthetic sling for female stress urinary incontinence.

Tension-free transvaginal tape (TVT) placement has recently become the preferred therapeutic approach for female stress urinary incontinence (SUI) in some centers. There are, however, no clearcut guidelines of how to treat patients in whom the procedure has failed. We describe our experience with repeat midurethral synthetic sling (MUS) implantation after a failed similar procedure. Twelve women (mean age 64.3 years) who had undergone a MUS procedure [TVT-9, intravaginal sling (IVS)-2, transobturator tape (TOT)-1] for SUI underwent a repeat MUS (TVT-5, IVS-4, TOT-3) due to persistent or recurrent SUI. The time from the first to the second procedure was 1-48 months. Eleven out of 12 patients (91.7%) achieved full continence (mean follow-up of 23.2 months, range 14-44). We conclude that a repeat MUS for persistent or recurrent SUI is a viable option for patients after an unsuccessful MUS procedure.

Tension-free vaginal tape procedure for the treatment of female stress urinary incontinence: long-term results.

PURPOSE: The tension-free transvaginal tape (TVT) procedure has apparently become the most popular technique for genuine stress urinary incontinence (GSUI). Long-term followup data on the outcome of the procedure are sparse. We evaluated the long-term results of TVT for treating women with GSUI. MATERIALS AND METHODS: We performed a retrospective analysis of the records of 55 patients 37 to 83 years old (mean age 63.4) with GSUI, for which they underwent the TVT procedure at our department as of December 1999. RESULTS: Of the 52 patients who were followed a mean of 55 months (range 48 to 65) 41 (78.9%) were dry. There were 4 intraoperative complication (7.3%), including bladder injury in 3 patients and urethral injury in 1. None required surgical re-intervention. Urgency was reported in 6 women (11.5%). There were 5 postoperative tape related complications (9.6%), consisting of bladder erosion in 1 woman, vaginal erosion in 2 and an obstructed urethra in 2. Four of these 5 women underwent corrective surgery, after which all remained dry. CONCLUSIONS: TVT is a safe and effective procedure for female stress urinary incontinence with an enduring, high success rate. There is a significant rate of intraoperative complications, which do not cause further problems when identified and treated during surgery. One must be alert to the significant rate of postoperative complications that usually require repeat surgery, which is relatively simple and causes practically no long-term morbidity. It also does not influence the continence rate in most cases.

Tape related complications of the tension-free vaginal tape procedure.

PURPOSE: The tension-free vaginal tape (TVT) procedure is a recent modality for managing female stress urinary incontinence. While this procedure is rapidly gaining popularity worldwide, little has been written about its complications. We describe our experience with diagnosing and treating tape related complications following the TVT procedure. MATERIALS AND METHODS: During the last 4 years 12 patients underwent and 1 is scheduled for additional surgery for complications resulting from the TVT. Another patient is only being observed. Their records were reviewed to retrieve data on presenting symptoms and signs, diagnostic tests, surgical procedures and outcomes. RESULTS: One patient had tape erosion into the bladder, 5 had vaginal tape erosion (concomitant urethral obstruction in 1) and another 8 had an obstructed urethra. The more common presenting symptoms were persistent urethral pain, recurrent urinary tract infection, urgency, urge incontinence and vaginal discharge. A total of 12 patients required partial tape removal or tape incision, which was done transvaginally in 11. The remaining patient underwent cystotomy and excision of the intravesical part of an eroded tape. One patient is awaiting corrective surgery and 1 with asymptomatic vaginal erosion is only being observed. No formal urethrolysis was performed in any case. Mean followup after corrective surgery in 12 patients was 4.8 months (range 1 to 30), during which 10 remained continent and all 12 were symptom-free. CONCLUSIONS: Urologists should be aware of the nature and symptoms of tape related complications associated with a TVT procedure for prompt diagnosis and appropriate postoperative management.

Bone anchor 4-corner cystourethropexy: long-term results.

PURPOSE: We evaluate the long-term results of incision less transvaginal bone anchor cystourethropexy to treat genuine urinary stress incontinence. MATERIALS AND METHODS: Between August 1995 and January 1997, 31 women 36 to 81 years old (mean age 58) with types I and II genuine urinary stress incontinence were treated. Four miniature bone anchors (2 on each side of the urethra) attached to a suture were fired transvaginally into the retropubic bone using a bone anchor stapler. The ipsilateral sutures were tied, thus creating a Marshall-Marchetti colposuspension. RESULTS: Of the patients 3 were lost to followup and the remaining 28 were followed for at least 60 months. Only 6 patients (21.4%) are continent. In 5 patients 11 sutures passed through the bladder 5 of which were removed intraoperatively and the other 6 were detected and removed during followup. Incontinence recurred in 1 patient because the sutures cut through the vaginal tissue and were found loose in the retropubic space. In 8 patients 12 anchors had become detached from the bone of which 7 were detected on x-ray in the retropubic area, 2 were removed cystoscopically 1 year later and 3 were spontaneously expulsed through the vagina 10 months to 5 years postoperatively. In 1 patient with intravesical sutures a vesicovaginal fistula developed which was successfully repaired, and in another pubic osteomyelitis developed. CONCLUSIONS: We regard 4-corner bone anchor cystourethropexy as unsuitable for genuine urinary stress incontinence based on the unfavorable outcome of incontinence and high rate of complications, including a relatively high incidence of confirmed anchor detachment.