Voltage-sensitive potassium channels in Drosophila photoreceptors

A preparation of dissociated Drosophila ommatidia is described that allows single-channel and whole-cell patch-clamp analysis of currents in identified sensory neurons. Three distinct classes of voltage-sensitive potassium conductances are characterized; all were detected in distal parts of ommatidia from sevenless mutants and hence in one cell class (R1-6 photoreceptors). Rapidly inactivating A-channels (IA), coded by the Shaker gene, were isolated in multichannel patches from adult flies. While showing similar kinetics to muscle A-channels, they differ from previously characterized wild-type Shaker channels in having a much more negative voltage operating range, being half-inactivated at approximately -70 mV. Two delayed rectifier conductances were characterized in whole-cell recordings from pupal photoreceptors. The most commonly encountered class (IKs) is similar to previously reported delayed rectifier conductances in Drosophila. It inactivates slowly (time constant, approximately 500 msec) and is half-inactivated at approximately -40 mV. A more rapidly inactivating delayed rectifier (IKf) was detected in approximately 30% of cells; it is half-inactivated at approximately -80 mV. Both IKs and IKf are blocked by 100 microM quinidine. Neither are greatly affected by 4-aminopyridine, which blocks IA at 1-5 mM. None of the three conductances was calcium dependent, nor were they obviously affected by the eag mutation, which affects K channels in muscle. The developmental profile of the channels is the inverse of that described in muscle. Both IKs and IKf are present at the earliest pupal stages examined (approximately 60 hr), but IA was only first detected at approximately 76 hr.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diplotypes of the human serotonin 1B receptor promoter predict growth hormone responses to sumatriptan in abstinent alcohol-dependent men.

BACKGROUND: Some studies have associated alcohol dependence (AD) with the human serotonin (5-HT)(1B) receptor (HTR1B). This investigation explored the functional responsivity of HTR1B in abstinent AD men using a sumatriptan challenge, while measuring genetic heterogeneity in the HTR1B promoter. METHODS: Abstinent AD men (n = 27) and abstinent men without any alcohol use disorder (n = 19) were administered 6 mg of sumatriptan succinate, subcutaneously. Plasma samples collected over the following 2 hours were assayed for growth hormone (GH) concentrations. His DNA was genotyped for the A-161T and T-261G polymorphisms of the HTR1B promoter and diplotypes determined. RESULTS: Integrated GH responses were predicted by interactions of AD and promoter diplotypes, as well as subject ethnicity. The final model accounted for nearly 35% of the variance in GH responses. Post hoc evaluation revealed that AD was associated with a blunting of GH secretion only among individuals with the most common HTR1B diplotype (TT/TT). CONCLUSIONS: A blunting of GH responses in abstinent AD men was observed only among those with the most common HTR1B promoter diplotype. Less common promoter diplotypes appeared protective. Controlling for genetic background is a useful augmentation of case-control pharmacological challenge strategies designed to elucidate the psychobiology of AD and other complex disorders.     

A scheme for the identification of viridans streptococci.

A collection of strains representing all the currently recognised species of oral or viridans streptococci (Streptococcus sanguis, S. parasanguis, S. gordonii, S. oralis, S. mitis, S. salivarius, S. vestibularis, S. anginosus, S. constellatus, s. intermedius, S. mutans and S. sobrinus) were tested for the production of a range of glycosidase activities with 4-methylumbelliferyl-linked fluorogenic substrates, and for reactions in a range of conventional fermentation and hydrolytic tests. The resulting biochemical scheme, consisting of 14 tests, enabled the differentiation of all these species and distinguished three biotypes within S. sanguis. The scheme reported here represents an improvement over currently available schemes for the identification of viridans streptococci.     

Concerns regarding infection control recommendations for dental practice.

It goes without saying that the members of any professional group are more likely to modify their behavior if they are provided with logical, rational reasons to enact the suggested change. In the mid 1980s, health care providers, including dental personnel, were advised to adopt universal precautions and to alter their infection control habits with minimal justification, apart from the general unease and paranoia surrounding AIDS. Therefore, it is understandable that some practitioners would react with scepticism to the idea that their traditional infection control techniques were less than adequate, while others would overwhelmingly embrace the new recommendations in the misguided belief that personal, patient, staff and family safety would be enhanced. This predictable confusion is epitomized by the dentist who "sterilizes" extraction forceps by immersing them in alcohol for 10 minutes, versus the dentist who wears gloves, mask and disposable gown to conduct a recall examination. And if dentists are perplexed, it is clear that their staffs are equally, if not more confused, since they are exposed to the exaggerated claims and counter claims of sales agents. The microbes encountered in dental practise, apart from the hepatitis B virus, pose no significant risk to dental personnel or their patients, and the danger of hepatitis B transmission is reduced most effectively by vaccination. In reality, the genesis of dentistry's current emphasis on infection control resides entirely with HIV disease. But there is no credible clinical evidence to suggest that HIV infection is transmitted via dental treatment. Indeed, it may be theorized that for such a transmission to occur, the blood stream of the susceptible recipient would have to be invaded directly by a pathogenic inoculum of the virus--an unlikely event in the normal practise of dentistry. Under such circumstances, infection control practises should ignore the danger of HIV transmission, but concentrate on: Sterilization of all surgical and invasive instruments to protect patients from potential cross-infection. All dental staff receiving hepatitis B vaccinations. Dental staff wearing gloves, especially while performing intraoral procedures with blood release, and handling used instruments, to protect them from direct contact with potential pathogens. Working in a clean environment, in which blood spills and splatters are removed mainly for esthetic reasons. Such measures reflect the actual potential for disease transmission, as it exists in dentistry. They are justified and economical, and will be implemented by concerned but knowledgeable dental staff.     

Production of immunoglobulins by human sIgD+ and sIgD- human blood B lymphocytes in response to stimulation with activated T cells and agonistic antibodies; effect of IL-10, IL-2 and mode of activation of T cells.

Production of IgM, IgG and IgA was induced from human blood B lymphocytes by culturing with a CD40 MoAb and IL-2 for 9 days. Replacement of IL-2 by IL-10 markedly enhanced production of all three isotypes. High levels of immunoglobulin production also occurred when activated irradiated autologous T cells replaced the CD40 MoAb, and when IL-10 replaced IL-2 in these cultures a spectacular increase in IgG production occurred. The effectiveness of the T cell stimulus depended on the mode of purification of the T cells and the nature of the stimulant used to activate them. Differences in the kinetics and level of expression of CD40L on the various T cell preparations were observed, but did not account for variations in immunoglobulin-inducing efficiency. Immunoglobulin production from sIgD+ and sIgD- B cells was investigated. IgG and IgA were found in sIgD+ cultures, indicating that some isotype switching had occurred, but the major part of the IgG and IgA secreted was from cells already committed to these isotypes. Anti-IgD or anti-IgM MoAbs enhanced the proliferation of B cells induced by anti-CD40 antibody, but immunoglobulin production was not enhanced. Factors affecting the balance of proliferation and differentiation are discussed.     

Operative morbidity and reproductive outcome in secondary myomectomy: a prospective cohort study

BACKGROUND: This prospective study was designed to evaluate the operative morbidity and reproductive outcome in patients who had secondary myomectomy for recurrent symptomatic uterine fibroids. METHODS: A total of 58 women were subjected to a secondary myomectomy via the abdominal route. The operative morbidity such as blood loss, presence of adhesions and febrile index were estimated and the pregnancy outcome over a 2-4 year period of follow-up. RESULTS: The mean age and standard deviation (+/- SD) of the women was 35 (+/- 2.4) years. Nineteen patients (33%) had a postoperative temperature vertical line 100 degrees F and the estimated blood loss ranged from 159-2500 ml (median 700 ml). Seven patients (12%) required blood transfusion and one had a hysterectomy due to haemorrhage. Nine women (15.5%) became pregnant but only five (56%) had live births. Those with successful pregnancies tended to be younger with a mean age of 31.8 (+/- 2.6) years versus 35 (+/- 1.8) years, (P = 0.08, non-significant) and had fewer uterine leiomyomata; median with range values, 2 (1-6) versus 7 (6-15). The variables which best predicted the postoperative likelihood of pregnancy were; age, presence of tubal adhesions and the number of uterine fibroids. CONCLUSION: This prospective study showed a high operative morbidity and a poor fertility outcome after a repeat myomectomy. The factors affecting successful outcome in a logistic regression model were age, tubal adhesions and number of uterine fibroids.     

Detecting antibodies with similar reactivity patterns in the HLDA8 blind panel of flow cytometry data

The blind panel collected for the 8th Human Leucocyte Differentiation Antigens Workshop (HLDA8; ) included 49 antibodies of known CD specificities and 76 antibodies of unknown specificity. We have identified groups of antibodies showing similar patterns of reactivity that need to be investigated by biochemical methods to evaluate whether the antibodies within these groups are reacting with the same molecule. Our approach to data analysis was based on the work of Salganik et al. (in press) [Salganik, M.P., Milford E.L., Hardie D.L., Shaw, S., Wand, M.P., in press. Classifying antibodies using flow cytometry data: class prediction and class discovery. Biometrical Journal].