Similar patterns of frequency-dependent selection on animal personalities emerge in three species of social spiders.

Frequency-dependent selection is thought to be a major contributor to the maintenance of phenotypic variation. We tested for frequency-dependent selection on contrasting behavioural strategies, termed here 'personalities', in three species of social spiders, each thought to represent an independent evolutionary origin of sociality. The evolution of sociality in the spider genus Anelosimus is consistently met with the emergence of two temporally stable discrete personality types: an 'aggressive' or 'docile' form. We assessed how the foraging success of each phenotype changes as a function of its representation within a colony. We did this by creating experimental colonies of various compositions (six aggressives, three aggressives and three dociles, one aggressive and five dociles, six dociles), maintaining them in a common garden for 3 weeks, and tracking the mass gained by individuals of either phenotype. We found that both the docile and aggressive phenotypes experienced their greatest mass gain in mixed colonies of mostly docile individuals. However, the performance of both phenotypes decreased as the frequency of the aggressive phenotype increased. Nearly identical patterns of phenotype-specific frequency dependence were recovered in all three species. Naturally occurring colonies of these spiders exhibit mixtures dominated by the docile phenotype, suggesting that these spiders may have evolved mechanisms to maintain the compositions that maximize the success of the colony without compromising the expected reproductive output of either phenotype.

Immunologic characterization of the membrane-bound collagen in normal human fibroblasts: identification of a distinct membrane collagen.

Collagen, the major extracellular matrix protein, is also a membrane protein. Two types of collagen are detected on the normal human fibroblast membrane in culture, type I collagen and a new immunologically and chemically distinct collagen, type M (membrane) collagen. Antibodies to type M collagen elicited complement-mediated cytotoxicity, which could be blocked by pretreatment of the cells with bacterial collagenase or the antibody with type M collagen. Pretreatment of the cells with other proteolytic enzymes or the antibody with type I collagen or type III collagen had no effect on this complement-mediated cytotoxicity. Although type I collagen is the major collagen synthesized by normal human fibroblasts type M collagen may be the major cell membrane collagen and may be a major cell membrane component.

Defect in conversion of procollagen to collagen in a form of Ehlers-Danlos syndrome.

Three patients with a form of the Ehlers-Danlos syndrome, a generalized disorder of connective tissue, have detectable amounts of procollagen in extracts of their skin and tendon. The activity of procollagen peptidase, the enzyme that converts procollagen to collagen, is reduced in cultures of fibroblasts. The clinical manifestations of this syndrome may be related to impaired enzymatic conversion of procollagen to collagen. Cultures of skin fibroblasts from these patients have an increased rate of synthesis of collagenous protein (collagen and procollagen), possibly related to the inability of these cells to convert procollagen to collagen.

The pursuit of the magic pill: the overuse of psychotropic medications in children with intellectual and developmental disabilities in the USA.

Children with intellectual and developmental disabilities (IDD) are likely to receive high-risk prescribing practices, such as polypharmacy, long-term use of psychotropic medications, and overuse of antipsychotics. Behavioural interventions, such as applied behavioural analysis, are evidence-based practices for children with IDD and should be the first-line treatment. Short-term use of psychotropic medications may be helpful in reducing the severity and frequency of challenging behaviours while evidence-based behavioural interventions are pursued. In this essay, we offer practical guidelines for better care.

Computer-assisted orthognathic surgery: evaluation of mandible registration accuracy and report of the first clinical cases of navigated sagittal split ramus osteotomy.

Intraoperative navigation is a helpful tool in complex anatomical regions or procedures. The mobility of the mandible in relation to the skull base limits the use of navigation tools on the lower jaw if the reference device is installed on the forehead. A new workflow that allows navigation-assisted sagittal split osteotomy in orthognathic surgery using a separate non-invasive mandibular registration technique has been developed. An evaluation of accuracy in different anatomical regions and with different registration techniques was performed on skull models and skulls with movable mandibles. The mean inaccuracy was 1.51mm, with no significant difference between anatomical sites. Using a splint-based reference device allows the movable mandible to be registered independently from the midface. Registration using metal points in the splint provides higher accuracy than using interdental anatomical landmarks. The workflow could be transferred successfully to patient treatment. Navigation-assisted osteotomy by Obwegeser-Dal Pont technique was performed without any complication in six patients. The mean deviation from the planned osteotomy line was 1.52mm. The navigated sagittal split ramus osteotomy seems to be a suitable technique to increase patient safety.

Defects in the biochemistry of collagen in diseases of connective tissue.

The collagens are the major structural glycoproteins of connective tissues. A unique primary structure and a multiplicity of post-translational modification reactions are required for normal fibrillogenesis. The post-translational modifications include hydroxylation of prolyl and lysyl residues, glycosylation, folding of the molecule into triple-helical conformation, proteolytic conversion of precursor procollagen to collagen, and oxidative deamination of certain lysyl and hydroxylysyl residues. Any defect in the normal mechanisms responsible for the synthesis and secretion of collagen molecules or the deposition of these molecules into extracellular fibers could result in abnormal fibrillogenesis; such defects could result in a connective tissue disease. Recently, defects in the regulation of the types of collagen synthesized and in the enzymes involved in the post-translational modifications have been found in heritable diseases of connective tissue. Thus far, the primary heritable disorders of collagen metabolism in man include lysyl hydroxylase deficiency in Ehlers-Danlos syndrome type VI, p-collagen peptidase deficency in Ehlers-Danlos syndrome type VII, decreased synthesis of type III collagen in Ehlers-Danlos syndrome type IV, lysyl oxidase deficency in S-linked cutis laxa and Ehlers-Danlos syndrome type V, and decreased synthesis of type I collagen in osteogenesis imperfecta.

Inflammatory conditions of the stomach and duodenum.

Upper gastrointestinal inflammatory processes are exceedingly common and have a wide spectrum of causes and manifestations. The broad category of acid-peptic disease incorporates the most common and important conditions. Concepts of pathophysiology of gastritis and duodenitis and their relationship to ulcers and neoplasm continue to evolve. The role of infection, especially H. pylori, remains under intense investigation. The spectrum of gastroduodenal inflammation in the immunocompromised host continues to expand and becomes increasingly important. A variety of granulomatous processes, both infectious and idiopathic, involve the upper gastrointestinal tract in overlapping patterns. Although investigation of ulcers and syphilis occupied the attention of the earliest gastrointestinal radiologists, related problems continue to challenge today's radiologic imagers, clinicians, and investigators.

Radiologic-pathologic correlation of inflammatory bowel disease.

The various inflammatory bowel diseases produce a wide spectrum of mucosal and bowel wall changes. No one radiolographic sign, or even combination of signs, is completely pathognomonic. A consideration of the pathophysiology responsible for the radiographic findings is helpful as an aid to understanding and to limit reliance upon matching of nonspecific signs with specific diagnosis. Patterns of mucosal ulceration, polyp formation, and strictures in the common superficial and transmural inflammatory diseases are emphasized.

Ambulatory visit groups: a framework for measuring productivity in ambulatory care.

This article describes Ambulatory Visit Groups (AVGs) and the process by which they were defined. An approach to the analysis of physician productivity in the ambulatory setting is then demonstrated, with data derived from the National Ambulatory Medical Care Survey [1]. Finally, recommendations for future work are presented to make this approach more effective in designing and managing ambulatory care delivery organizations.

Procedure codes: potential modifiers of diagnosis-related groups.

Proposals to make complexity-of-illness adjustments to the diagnosis-related group system have relied on secondary diagnosis codes and additional clinical information obtained from the hospital record. Another potential mechanism for modifying diagnosis-related groups involves the use of non-operating room procedure codes. The use of these codes has the advantage of reliably identifying costly subgroups of patients and thus the potential to provide for fairer compensation to hospitals caring for the sickest patients. There are a number of disadvantages, however, and therefore the criteria with which to evaluate procedures as potential modifiers are suggested.

Hydroxylysine-deficient skin collagen in a patient with a form of the Ehlers-Danlos syndrome.

Two sibs with the Ehlers-Danlos syndrome, one of whom was shown to have hydroxylysine-deficient collagen, are described. In addition to the usual features of the Ehlers-Danlos syndrome (loose-jointedness and excessively stretchable, fragile, and bruisable skin), these patients had severe scoliosis and fragility of ocular tissues leading to rupture of the globe or retinal detachment. This combination of symptoms was tentatively classified as Ehlers-Danlos syndrome, Type VI. The condition is inherited as an autosomal recessive. The activity of lysyl hydroxylase was present at a reduced level in fibroblasts cultured from the patient's skin.

A case report of ascariasis of the common bile duct in a patient who had undergone cholecystectomy.

This is a case report of ascariasis of the common bile duct in a 65-year-old man from Colombia who had undergone prior cholecystectomy. The patient presented with postprandial epigastric pain and a 20-lb weight loss. The laboratory findings were remarkable for peripheral blood eosinophilia. The ultrasound finding was suggestive of periampullary or pancreatic neoplasm. He underwent endoscopic retrograde cholangiopancreatography with endoscopic extraction of a motile, live worm identified as Ascaris lumbricoides. Roundworm infestation should always be suspected in immigrants from endemic areas who present with hepatobiliary symptoms.

Role of radiology in aviation accident investigation.

Radiographic screening of fatality victims for skeletal detail, dental and surgical artifacts, personal effects, and foreign bodies is of established value. Radiography as the primary means of positive victim identification, through comparison with antemortem films and records, is an important new role. Data on sources of injury and relationships between victims and the crash environment may be derived from radiographic injury patterns and may be correlated with mechanisms of injury production. The result of such analysis is improved safety design. Such radiography poses unique technical and logistical problems, often involving temporary or remote facilities, which must be solved with consideration for privacy and safety. Advance planning is essential for maximum benefit from radiographic investigation.

Factors affecting pension and health benefits availability in small and large business.

Factors affecting the provision of fringe benefits are receiving more attention as fringe benefits have become an increasingly important component of total compensation. Despite the importance of trends in fringe benefits to businesses and the economy, the effects of factors--including firm size--on the provision of fringe benefits have received only limited systematic attention. Studies have examined either worker characteristics or firm/establishment/ industry characteristics, but few have combined both types of characteristics to study a more comprehensive set of determinants. The author addresses this limitation using new data from a nationally representative sample of almost 600 firms. The focus of this study is on the two most important fringe benefits--pension plans and health insurance.