Ecological divergence and sexual selection drive sexual size dimorphism in New World pitvipers (Serpentes: Viperidae).

Hypotheses for the origin and maintenance of sexual size dimorphism (SSD) fall into three primary categories: (i) sexual selection on male size, (ii) fecundity selection on female size and (iii) ecological selection for gender-specific niche divergence. We investigate the impact of these forces on SSD evolution in New World pitvipers (Crotalinae). We constructed a phylogeny from up to eight genes (seven mitochondrial, one nuclear) for 104 species of NW crotalines. We gathered morphological and ecological data for 82 species for comparative analyses. There is a strong signal of sexual selection on male size driving SSD, but less evidence for fecundity selection on female size across lineages. No support was found for allometric scaling of SSD (Rensch's rule), nor for directional selection for increasing male size (the Fairbairn-Preziosi hypothesis) in NW crotalines. Interestingly, arboreal lineages experience higher rates of SSD evolution and a pronounced shift to female-biased dimorphism. This suggests that fecundity selection on arboreal females exaggerates ecologically mediated dimorphism, whereas sexual selection drives male size in terrestrial lineages. We find that increasing SSD in both directions (male- and female-biased) decreases speciation rates. In NW crotalines, it appears that increasing magnitudes of ecologically mediated SSD reduce rates of speciation, as divergence accumulates within species among sexes, reducing adaptive divergence between populations leading to speciation.

A census of general surgery consultants in England and Wales: implications for the current and future surgical workforce.

INTRODUCTION: This study aimed to describe the composition of the current general surgical consultant body in England and Wales and quantify levels of inequality within it as well as describe future workforce challenges. METHODS: This is an observational study of all general surgical departments in England and Wales. Consultant general surgeons were identified and data regarding their gender, country of undergraduate medical education, subspecialty and private practice were recorded. RESULTS: Of the 2,682 consultant general surgeons in England and Wales identified for this study, just 17% are women, with gender inequality most marked in university teaching hospitals and among certain subspecialties. Almost 40% of consultants did not obtain their primary undergraduate degree in the United Kingdom and there are considerably fewer surgeons who studied abroad in university teaching hospitals. Over 40% of current general surgical consultants have been qualified for more than three decades and there is no equivalent sized group of younger consultants. CONCLUSIONS: There remains considerable gender and racial inequality in the consultant general surgical workforce, with pockets of a lack of diversity within university or teaching hospital surgical departments and some subspecialties. The proportion of surgeons in their fourth decade of clinical practice represents the largest group of current practising consultants, which points towards an impending workforce crisis should senior clinicians seek to reduce activity or consider taking early retirement.

Acid precipitation and sulfate deposition in Florida.

The acidity of rainfall in Florida has increased markedly in the past 25 years, and the average sulfate and nitrate concentrations have increased by factors of 1.6 and 4.5, respectively, over the period. Annual average pH values below 4.7 now occur over the northern three quarters of the state. Summer rainfall has average pH values 0.2 to 0.3 unit lower than winter rainfall, and sulfate concentrations at most sites are higher in summer. The annual deposition of H(+) (about 300 to 500 equivalents per hectare) in northern Florida is a third to a half of the deposition in the heavily impacted northeastern United States; comparable figures for excess sulfate (derived from sulfur dioxide) are 7 to 11 kilograms of sulfur per hectare or 50 to 90 percent of the sulfate deposition rates at Hubbard Brook, New Hampshire.

Childhood disintegrative disorder: should it be considered a distinct diagnosis?

First termed Dementia Infantilis by Theodore Heller in 1908, Childhood Disintegrative Disorder (CDD) has had a history longer than that of Autistic Disorder. Presently, CDD is classified as a Pervasive Developmental Disorder in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. The characteristics most often cited as distinguishing CDD from Autistic Disorder, another one of the Pervasive Developmental Disorders, is the age of onset and evidence of normal development prior to the presence of symptomatology. Otherwise, the behavioral symptoms of CDD and Autistic Disorder are strikingly similar. The purpose of this article is to provide a historical background on CDD, examine the evolution of diagnostic criteria, review the existing literature pertaining to the disorder, and, finally, to draw conclusions regarding the validity of CDD as a distinct diagnosis with reference to current and alternative classification approaches.

The nurse teacher as Action Researcher.

It is important that the work of nurse education and nurse educators is critically evaluated. Just as it is no longer acceptable for clinical practitioners of nursing to engage in nursing activities out of a sense of tradition or a history of habit and practice, so too must nurse educators engage in systematic evaluation of their own craft. A number of authors have described Action Research's suitability for nursing (Webb 1990, Greenwood 1984, MacGuire 1991). In this paper the authors examine Action Research from the perspective of nurse teachers and suggest that it is an appropriate method for studying nurse education.

Teaching practical skills: a guide for preceptors.

Concern has been expressed that recently qualified nurses may be deficient in clinical skills. In this article the authors explore psychomotor skills learning and suggest strategies to support preceptors who have responsibility for developing such skills in students. The advice should prove helpful to clinical staff who are involved in teaching clinical skills to nursing students.

Reviewing the literature: a guide for students.

This article aims to help students develop the skills of searching, analysing and critiquing the literature so that they can make sense of the vast amount of written material they will have to read, both while they are studying and throughout their careers.

Understanding allergies and their treatment.

Allergies are common and although their effects are often minor, they can be life threatening. The authors discuss the background to allergy and give guidance for prevention and management.

Perioperative transfusion for pancreaticoduodenectomy and its impact on prognosis in resected pancreatic ductal adenocarcinoma.

BACKGROUND AND AIMS: Pancreaticoduodenectomy (PD) is a major operative intervention performed most commonly for malignancy in the head of pancreas. The aim of this study was to evaluate the utilization of blood transfusion for PD and to determine whether this had prognostic significance in a subset of patients with pancreatic ductal adenocarcinoma (PDAC). MATERIAL AND METHODS: Data on blood transfusion requirement were retrospectively collected for patients undergoing PD from 1998 to 2005. Standard prognostic factors and survival data were also collected in patients with PDAC. RESULTS: One-hundred-and-seventy patients underwent PD. Seventy-six patients (45%) received transfusion. The median (interquartile range) number of units of red cell concentrate (RCC) transfused perioperatively (intraoperatively and within 24 h of surgery) was 1.5 (0.5-2.5). The median preoperative haemoglobin (Hb) was 126 g/dl. The median number of units of RCC transfused perioperatively in patients with Hb <126 g/dl was 2 (1-3); for those with Hb > or = 126 g/dl the median was 0 (0-1); p=0.003. Forty-nine patients who were resected for PDAC were subjected to survival analysis. Univariate and multivariate analyses showed that only posterior resection margin invasion was associated with an adverse outcome (margin positive 198 [143-470] days vs margin negative 398 [303-859] days; p=0.02). Perioperative RCC transfusion requirement was not a significant predictor of survival (transfusion 408 [214-769] days vs no transfusion 331 [217-391] days; p=0.18). Furthermore, RCC transfusion within 30 days of operation was not a significant predictor of poor survival (transfusion 331 [201-459] days vs no transfusion 317 [196-769] days; p=0.43). CONCLUSIONS: PD can be performed with a moderately low requirement for RCC transfusion; however, low preoperative haemoglobin is a predictor for the requirement of RCC transfusion. Administration of RCC transfusion does not appear to be a significant adverse prognostic factor in patients with resected PDAC.

Isolation and partial characterization of dermatan sulfate proteoglycans from human post-burn scar tissues.

Dermatan sulfate (DS) proteoglycans (PGs) were extracted from human post-burn scar (Sc) tissues with 4M guanidinium chloride and isolated from the extracts by DEAE-cellulose chromatography and by differential ethanol precipitation. The DS.PGs were further purified by Sepharose CL-6B column chromatography. The average molecular weight (Mr) of hypertrophic scar (HSc) tissue DS.PGs was 39,000 based on sedimentation equilibrium measurements. Alkaline borohydride treatment of DS.PGs liberated glycosaminoglycan (GAG) chains and the presence of xylitol indicated that these chains were attached to protein core by xylosyl residues. The average Mr of the DS.GAG chain from HSc and normal scar (NSc) samples were 23,500 and 20,000 respectively. After digestion of the HSc and NSc, DS.PGs with chondroitinase ABC in the presence of proteinase inhibitors, two peptide components with Mr values of 21,500 and 17,000 were detected by SDS-polyacrylamide gel electrophoresis using reducing conditions. Analysis of the protein core fractions derived from NSc and HSc DS.PGs by Sepharose CL-6B column chromatography showed the presence of a single NH2-terminal amino acid (aspartic acid) and also that the fractions with different KAV values had an identical NH2-terminal sequence (A1-A5). The A1-A23 sequence of NSc DS.PG (major fraction, C): NH2Asp-Glu-Ala-O-Gly-Ile-Gly-Pro-Glu-Val-Pro-Asp-Asp-Arg-Asp-Phe-G lu-Pro- Ser-Leu-Gly-Pro-Val was the same as reported for a DS.PG isolated from human fetal membrane (HFM) tissue (Brennan et al., 1984). ELISA inhibition assay using monoclonal antibodies raised in rabbit against the NH2-terminal peptide (containing 15 amino acids) of human fetal membrane tissue were found to cross-react with HSc and NSc DS.PGs. Monoclonal antibodies to bovine skin DS.PGs protein core (Pearson et al., 1983) did not show any cross-reactivity with scar DS.PGs. These results show that the scar DS.PGs described here are different from normal bovine skin DS.PGs in the size and type of the protein core, and that in all the samples, the peptide components have the same NH2-terminal amino acid sequence.