False-negative results by polymerase chain reaction due to contamination by glove powder

The polymerase chain reaction (PCR) technique has become an important, widely employed method for the detection and quantitation of the nucleic acid sequences used in the diagnosis and monitoring of genetic and infectious diseases. Much attention has been directed at the problem of false-positive PCR results, which are generally attributed to low-level laboratory contamination of amplified sequences ("carryover"). In contrast, few investigators have commented on the somewhat less frequent, but equally problematic, false-negative PCR results. Investigation of the source of sporadic false-negative PCR reactions found that glove powder, inadvertently introduced into tubes when gloves are changed in an effort to reduce false-positive results, can nonspecifically inhibit each of the major steps in the PCR detection process. Methodologic precautions are recommended to minimize this problem.     

Class-II and IL 2 receptor positive cells in the pancreas of NOD mice

Summary The aberrant expression of Class-II molecules on pancreatic B cells in Type 1 (insulin-dependent) diabetes is still a matter of debate. In order to verify if Class-II molecules are expressed on islet cells in the NOD mouse we have studied 21 female mice of different ages (5 to 22 weeks). Serial cryostat pancreas sections were stained with monoclonal rat antibodies against Class-II antigens (P7/7) and the IL2 receptor (AMT-13). Our results show no Class-II expression by endocrine cells at any age, whereas about 25–32% of mononuclear cells infiltrating the islets were Class-II positive, and only 6–9% were IL2 receptor positive. No staining, except of occasional tissue macrophages, was observed in the pancreas of BALB/c, CBA or B10.SCSN mice. Our data are in contrast with those recently published and therefore the reality of expression of Class-II molecules by islet cells of NOD mice should be viewed with caution.     

Premovement high‐alpha power is modulated by previous movement errors: Indirect evidence to endorse high‐alpha power as a marker of resource allocation during motor programming

Previous electroencephalographic studies have identified premovement high‐alpha power as a predictor of movement accuracy; less frontal‐central high‐alpha power is associated with accurate movements (e.g., holed golf putts), and could reflect more cognitive resources being allocated to response programming. The present experiment tested this interpretation. Ten expert and ten novice golfers completed 120 putts while high‐alpha power was recorded and analyzed as a function of whether the previous putt was holed (i.e., a correct response) or missed (i.e., an error). Existing evidence indicates that more resources are allocated to response programming following errors. We observed less premovement high‐alpha power following errors, especially in experts. Our findings provide indirect evidence that high‐alpha power is an inverse marker of the amount of resources allocated to motor response programming.     

The demand incidence of symptomatic ankle osteoarthritis presenting to foot & ankle surgeons in the United Kingdom

BackgroundAnkle arthritis is a cause of major disability; however reports in the literature on the incidence of ankle osteoarthritis are rare.ObjectivesTo explore the methodological challenges in obtaining an incidence of ankle osteoarthritis and to estimate the incidence of symptomatic osteoarthritis presenting to Foot & Ankle specialists in the UK.MethodsWe searched available national diagnosis databases and also sent out a questionnaire-based survey to all Consultant members of the British Orthopaedic Foot & Ankle Society (n = 180).Results123 completed survey questionnaires were returned (68%) with each surgeon seeing on average 160 cases of symptomatic ankle arthritis and performing on average 20 definitive procedures for end-stage ankle osteoarthritis per year. There are no internationally agreed diagnostic or treatment codes specific for ankle osteoarthritis.ConclusionThere are an estimated 29,000 cases of symptomatic ankle osteoarthritis being referred to specialists in the UK, representing a demand incidence of 47.7 per 100,000. 3000 definitive operations to treat end stage ankle osteoarthritis take place in the UK annually. We recommend that specific codes pertaining to ankle arthritis and its treatment be included in any future revisions of the WHO International Classification of Diseases (ICD) and operative procedure coding systems.     

A human DAZ transgene confers partial rescue of the mouse Dazl null phenotype

In a subset of infertile men, a spectrum of spermatogenic defects ranging from a complete absence of germ cells (sertoli cell only) to oligozoospermia is associated with microdeletions of the DAZ (deleted in azoospermia) gene cluster on human distal Yq. DAZ encodes a testis-specific protein with RNA-binding potential recently derived from a single-copy gene DAZL1 (DAZ-like) on chromosome 3. Y chromosomal DAZ homologues are confined to humans and higher primates. It remains unclear which function unique to higher primate spermatogenesis DAZ may serve, and the functional status of the gene recently has been questioned. To assess the extent of functional conservation we have tested the capacity of a human DAZ gene contained in a 225-kb yeast artificial chromosome to complement the sterile phenotype of the Dazl null mouse (Dazl-/-), which is characterized by severe germ-cell depletion and meiotic failure. Although Dazl-/- mice remained infertile when the DAZ transgene was introduced, histological examination revealed a partial and variable rescue of the mutant phenotype, manifest as a pronounced increase in the germ cell population of the seminiferous tubules and survival to the pachytene stage of meiosis. As well as constituting definitive proof of the spermatogenic role of the DAZ gene product, these findings confirm the high degree of functional conservation between the DAZ and DAZL1 genes, suggesting they may constitute a single target for contraceptive intervention and raising the possibility of therapeutic up-regulation of the DAZL1 gene in infertile men.     

PROTEOSE INTOXICATIONS AND INJURY OF BODY PROTEIN : II. THE METABOLISM OF DOGS WITH DUODENAL OBSTRUCTION AND ISOLATED LOOPS OF INTESTINE.

Dogs with isolated loops of small intestine show many evidences of intoxication. A study of the total nitrogen elimination shows a great rise above the normal base-line minimum of the fasting period (Table II). This means that the intoxication is associated with a great destruction of body protein, and explains the high non-protein nitrogen of the blood which was observed and reported previously (2). Injection of a proteose obtained from a closed intestinal loop will cause a similar rise in the nitrogen elimination curve. This furnishes more evidence that the intoxication observed in association with a closed intestinal loop is in reality a proteose intoxication. Dogs injected with sublethal doses of proteose will show a definite tolerance to subsequent injection, and will show much less acute intoxication after the isolation of a closed intestinal loop (Table 1). These immune or tolerant dogs show a much less pronounced rise in the nitrogen elimination curve during proteose intoxication of any type. This indicates that the tolerance or immunity to proteose gives more protection for the body proteins against the injury which these toxic proteoses inflict upon the body cells. Complete duodenal obstruction combined with a gastrojejunostomy gives a chronic type of intestinal obstruction associated with little vomiting, which is peculiarly suited to metabolism study (Table IV). Such duodenal obstructions show a definite and sustained rise in the curve of nitrogen elimination above the normal base-line level. These dogs, too, are tolerant to injections of standard toxic proteoses. Control ether anesthesia experiments show little if any rise in the curve of nitrogen elimination (Table VI). Control laparotomy experiments show a definite rise in the curve of nitrogen elimination, but a rise which is small compared with the rise noted in the intoxication of duodenal obstruction or of isolated intestinal loops. It is probable that the tissue injury and disintegration associated with the wound reaction are responsible for the general reaction. We may assume that protein split products from the wound area are absorbed and are responsible for the general reaction observed. We propose to assume that the intoxications here studied are associated with a definite proteose intoxication, which is capable of initiating and continuing a profound injury of tissue protein. One index of this protein injury is the great and sustained rise in the curve of total nitrogen elimination.