Cholesterol and ergosterol superlattices in three-component liquid crystalline lipid bilayers as revealed by dehydroergosterol fluorescence

We have examined the fractional sterol concentration dependence of dehydroergosterol (DHE) fluorescence in DHE/cholesterol/dimyristoyl-L-alpha-phosphatidylcholine (DMPC), DHE/ergosterol/DMPC and DHE/cholesterol/dipalmitoyl-L-alpha-phosphatidylcholine (DPPC) liquid-crystalline bilayers. Fluorescence intensity and lifetime exhibit local minima (dips) whenever the total sterol mole fraction, irrespective of the DHE content, is near the critical mole fractions predicted for sterols being regularly distributed in hexagonal superlattices. This result provides evidence that all three of these naturally occurring sterols (e.g., cholesterol, ergosterol, and DHE) can be regularly distributed in the membrane and that the bulky tetracyclic ring of the sterols is the cause of regular distribution. Moreover, at the critical sterol mole fractions, the steady-state anisotropy of DHE fluorescence and the calculated rotational relaxation times exhibit distinct peaks, suggesting that membrane free volume reaches a local minimum at critical sterol mole fractions. This, combined with the well-known sterol condensing effect on lipid acyl chains, provides a new understanding of how variations in membrane sterol content change membrane free volume. In addition to the fluorescence dips/peaks corresponding to hexagonal superlattices, we have observed intermediate fluorescence dips/peaks at concentrations predicted by the centered rectangular superlattice model. However, the 22.2 mol% dip for centered rectangular superlattices in DHE/ergosterol/DMPC mixtures becomes diminished after long incubation (4 weeks), whereas on the same time frame the 22.2 mol% dip in DHE/cholesterol/DMPC mixtures remains discernible, suggesting that although all three of these sterols can be regularly distributed, subtle differences in sterol structure cause changes in lateral sterol organization in the membrane.     

Autoantibodies--regulators of biochemical and physiological processes in the healthy body. Their place in phylogeny and among other endogenous regulators]

Interleukin-6 (IL-6) is known to enhance osteoclast recruitment, and thereby bone resorption. Thus, IL-6 has been proposed to mediate hypercalcemia in multiple myeloma and the enhanced osteoclastic activity seen in postmenopausal osteoporosis. We recently reported that the calcium concentration in plasma affects IL-6 secretion from mononuclear blood cells. To investigate the underlying mechanism, we have studied the effect of calcium on IL-6 formation in mononuclear blood cells ex vivo and in vitro. Thirteen healthy volunteers were given 1 g of calcium orally after overnight fasting. Plasma levels of ionized calcium (pCa2+) and serum levels of parathyroid hormone (sPTH) were measured after 2 and 4 h, with all subjects still fasting. After 2 h, pCa2+ was increased and sPTH decreased in all 13 persons. IL-6 secretion ex vivo from mononuclear blood cells drawn 4 h after calcium intake was increased 185% as compared with IL-6 secretion from cells drawn just before calcium intake. In control experiments without calcium intake, there was no alteration in pCa2+ and no effect on IL-6 secretion from mononuclear blood cells. In vitro studies revealed that stimulation of isolated mononuclear blood cells with physiological concentrations of calcium dose-dependently increased IL-6 secretion with an estimated EC50 at 1.2 mM Ca2+. No effect on the IL-6 secretion was seen following treatment of the isolated mononuclear blood cells with PTH or calcitonin. These observations demonstrate that the plasma calcium concentration affects IL-6 secretion from mononuclear blood cells. The in vitro data indicate the involvement of a direct calcium sensing mechanism. These findings might have implications in hypercalcemia and should also be borne in mind when considering the role of cytokines in osteoporosis.     

Fine mapping of the hereditary sensory neuropathy type I locus on chromosome 9q22.1-->q22.3: exclusion of GAS1 and XPA

BACKGROUND: Knowledge about the natural course of HPV infection is still limited. In this study we investigated the presence of HPV DNA after treatment and clinical clearance of infection. METHODS: Eighty-two women treated for genital HPV infection at the STD clinic in Uppsala were consecutively selected for the study. After treatment with podophyllotoxin, and in some cases laser vaporization, a cell sample was taken at the follow-up visit 6-12 months after clinical clearance of the lesions as evaluated by colposcopy. Samples were analysed with PCR to detect HPV DNA. As a reference group, women treated for cervical intraepithelial neoplasia (CIN) with laser surgery, either with cone biopsy or vaporization, were followed-up after 6 months for the presence of HPV DNA. RESULTS: Six to 12 months after clinical clearance of HPV infection, 39 (48%) of the women showed detectable HPV DNA in cell samples from the cervix. Of these, 26 (67%) were found to harbor high risk HPV, six (15%) low risk, and seven (18%) either had more than one HPV type or HPV that could not be classified. All but three of the women treated for CIN (90%) were negative for HPV DNA. CONCLUSION: After clinical clearance of genital HPV infection half of the women had detectable HPV DNA. This does not necessarily imply that transmission to a new partner may occur, but indicates this possibility. Only 10% of the CIN treated women harbored HPV DNA in the cell samples in spite of showing high risk HPV infection before treatment.     

Prophylaxis of neurological manifestations of lumbar osteochondrosis: intermediate results, unsolved problems and some methodologic aspects

Issues of prophylaxis and rehabilitation are considered as regards neurologic manifestations of spinal osteochondrosis (NMSO). NMSO primary prophylaxis requires investigation and quantitative evaluation of the disease risk factors, epidemiologic determination of both incidence and prevalence in different groups of population in various periods of time. The standard risk group of NMSO in Byelorussian consists of population of 40-49-year-olds. Some professions may be risk factors for both onset and relapse of NMSO. Secondary prophylaxis of NMSO concerns elevated relapse risk, screening for individuals with either subclinic or early clinic manifestations of the disease. The computer screening-system has been created to identify a group at high risk of NMSO onset or relapse, to keep records, to print documents. It also gives chance to carry out individual prophylaxis of the high risk in the course of mass examination of employees.     

下一代IP网与第五代路由器

目前人们面临网络建设方向的选择，QoS、安全性和可信任性、IP网的可运营性等关键技术成为未来网络发展重点。下一代IP网络将采用IP网的核心技术。结合电信网的设计理念，建设一个可管理、可运营的网络，为运营商提供一个可以达到电信网服务质量保证的IP网，建立可赢利的商业模型。第五代路由器由于采用有智能的网络处理器(NP)，可以灵活加进对用户的管理等多种功能，完全适应下一代IP网的发展要求。     

The effect of mammalian anxiety factors on insects. The action of the corticoliberin 2-4 fragment on the behavior of the mealworm beetle Tenebrio molitor

The effect of the corticoliberin 2-4 fragment--tripeptide Pro-Pro-Ile (PPI) inducing increase in epileptiform activity of mammal on T. molitor males behaviour has been studied. The "open field" method modified for insects has been used. PPI in doses of 30, 60, 100, 1000 micrograms/kg was injected in hemolymph of the beetles. The horizontal activity (HA), number of turns (TN) and other parameters were registered during 6 min. The tripeptide in dose 30 micrograms/kg was non-effective. PPI in doses 100 and, especially, 1000 micrograms/kg evoked stable decrease in HA that was observed as early as 0.5 h after injection. This effect lasted throughout 4-24 hrs and, apparently, induced by nonspecific action of high doses of the peptide. PPI in dose 60 micrograms/kg produced the significant intensification of stressogenic influence of experimental situation: in 2-4 hrs after injection the level of HA and TN increased. It is suggested that PPI can be regarded as an anxiogenic factor of insects.