Lipid phase transitions in cytoplasmic and outer membranes of Escherichia coli

The cytoplasmic and outer membranes containing either trans-Δ⁹-octadecenoate, trans-Δ⁹-hexadecenoate or cis-Δ⁹-octadecenoate as predominant unsaturated fatty acid residues in the phospholipids were prepared from a fatty acid auxotroph, Escherichia coli strain K1062. Order-disorder transitions of the phospholipids were revealed in both fractions of the cell envelope by fluorescent probing or wide angle X-ray diffraction. The mid-transition temperatures, $\text{T}\text{t}$, and the range of the transition, $\text{ΔT}$, are similar in the outer and cytoplasmic membrane. Relative to the corresponding extracted lipids, 60–80% of the hydrocarbon chains take part in the transition in the cytoplasmic membrane whereas in the outer membrane only 25–40% of the chains become ordered. The results suggest that in the outer membrane part of the lipids form fluid domains in the form of mono- and/or bilayers.     

Energy requirement for pullulanase secretion by the main terminal branch of the general secretory pathway

The energy requirement for the second step in pullulanase secretion by the general secretory pathway was studied in Escherichia coli . In order to uncouple the two steps in the secretion pathway (across the cytoplasmic and outer membranes, respectively) and to facilitate kinetic analysis of secretion, a variant form of pullulanase lacking its N-terminal fatty acid membrane anchor was used. The transport of the periplasmic secretion intermediate form of this protein across the outer membrane was not inhibited by concentrations of sodium arsenate in excess of those required to reduce ATP levels to ≤10% of their normal value. Pullulanase secretion was inhibited by the protonophore carbonyl cyanide m -chlorophenyl hydrazone at concentrations which were similar to those reported by others to be required to prevent solute uptake or the export and processing of preproteins across the cytoplasmic membrane, but which were in excess of those required to fully dissipate the proton-motive force and to reduce lactose uptake to a significant extent.     

Case-control study of oestrogen replacement therapy and risk of cervical cancer.

OBJECTIVE: To examine the relation between use of oestrogen replacement therapy and risk of cervical cancer. DESIGN: Case-control study. SETTING: Northern Italy. SUBJECTS: 645 women aged 40-75 years with cervical cancer admitted between 1981 and 1993 to university and general hospitals. The control group consisted of 749 women aged 40-75 years admitted to the same hospitals with acute conditions judged to be unrelated to any of the known or suspected risk factors for cervical cancer. MAIN OUTCOME MEASURES: Use of oestrogen replacement therapy and risk of cervical cancer. RESULTS: 40 cases versus 86 controls had ever used oestrogens, and the corresponding multivariate odds ratio was 0.5 (95% confidence interval 0.3 to 0.8). The odds ratios of cervical cancer decreased with duration of use, being 0.6 (0.4 to 1.1) for less than 12 months'' use and 0.5 (0.2 to 1.0) for use for 12 months or more compared with never users. The protection tended to be somewhat stronger for women reporting first oestrogen use before age 50. The odds ratio was 0.9 (0.5 to 1.7) for women who had taken oestrogens within the past 10 years and 0.4 (0.2 to 0.7) for those who had taken them 10 or more years ago. CONCLUSION: These findings suggest that exogenous oestrogens do not increase the risk of cervical cancer and may decrease the risk.     

Variations of biogenic amine levels in the brain of Pieris brassicae pupae during nondiapausing and diapausing development

The post-embryonic development of Pieris brassicae can either be continuous (under a long photoperiod) or interrupted at the pupal stage (induced by a short photoperiod); this phenomenon is termed facultative diapause. Several studies have indicated that certain brain mechanisms could be directly involved in the perception of variations in the photoperiod and could mediate some physiological effects particular to dormancy. Biogenic amines have been particularly implicated in the response to photoperiod variations and also in the regulation of development, especially in diapause induction and termination. High performance liquid chromatography with dual electrochemical detection has therefore been used to measure several biogenic amines in pupal nervous tissues at various stages of nondiapausing and diapausing development. During direct development, the levels of dopamine (DA) and N-acetyldopamine (NADA: a DA metabolite) in brain were relatively high in 3-day-old pupae and at the end of pupal life (on the 8th day). Dihydroxyphenylacetic acid (another metabolite of DA) showed no variation. Serotonin was mainly observed in 2–3-day-old pupae but 5-hydroxyindoleacetic acid was never detected. In young diapausing insects, similar variations of DA levels were observed even though a slight decrease of DA metabolites was noted. Serotonin appeared somewhat later (4–5 days) and attained higher levels. In late diapausing pupae, a marked increase in DA levels was observed, especially when pupae were kept at low temperature (4°C). During diapause, serotonin levels were reduced or even absent.     

Remission of established disease in diabetic NOD mice induced by anti-CD3 monoclonal antibody]

Anti-CD3 monoclonal antibodies are potent immunosuppressants widely used in clinical transplantation to prevent or treat acute allograft rejection. We have used a hamster monoclonal antibody (145 2C11) specific for the epsilon chain of the murine CD3 complex to treat autoimmune insulin-dependent diabetes appearing spontaneously by 15 to 30 weeks of age in female Non Obese Diabetic (NOD) mice. Mice showing overt disease (glycosuria and glycemia > or = 4 g/l) were randomized in two groups receiving either anti-CD3 (5 micrograms/day i.v. for 5 consecutive days) or an identical dose of hamster polyclonal immunoglobulins. Progressive remission of disease was observed, 3 to 6 weeks after the end of treatment, in 80% of anti-CD3 treated mice as compared to 6% of mice in the control group. This remission was maintained long term namely, during the 4 to 5 months (after the end of treatment) observation period. These results open interesting perspectives on the possibility to treat recently diagnosed diabetic patients with therapy showing long term efficacy and no chronic toxicity.     

The Effects of Ivermectin on Brugia malayi Females In Vitro: A Transcriptomic Approach

BackgroundLymphatic filariasis and onchocerciasis are disabling and disfiguring neglected tropical diseases of major importance in developing countries. Ivermectin is the drug of choice for mass drug administration programs for the control of onchocerciasis and lymphatic filariasis in areas where the diseases are co-endemic. Although ivermectin paralyzes somatic and pharyngeal muscles in many nematodes, these actions are poorly characterized in adult filariae. We hypothesize that paralysis of pharyngeal pumping by ivermectin in filariae could result in deprivation of essential nutrients, especially iron, inducing a wide range of responses evidenced by altered gene expression, changes in metabolic pathways, and altered developmental states in embryos. Previous studies have shown that ivermectin treatment significantly reduces microfilariae release from females within four days of exposure in vivo, while not markedly affecting adult worms. However, the mechanisms responsible for reduced production of microfilariae are poorly understood.Conclusion/SignificanceThese changes provide insight into the mechanisms involved in ivermectin-induced reduction in microfilaria output and impaired fertility, embryogenesis, and larval development.     

Role of the melanin-concentrating hormone neuropeptide in sleep regulation

Melanin-concentrating hormone (MCH), a neuropeptide secreted by a limited number of neurons within the tuberal hypothalamus, has been drawn in the field of sleep only fairly recently in 2003. Since then, growing experimental evidence indicates that MCH may play a crucial role in the homeostatic regulation of paradoxical sleep (PS). MCH-expressing neurons fire specifically during PS. When injected icv MCH induces a 200% increase in PS quantities in rats and the lack of MCH induces a decrease in sleep quantities in transgenic mice. Here, we review recent studies suggesting a role for MCH in the regulation of the sleep–wake cycle, in particular PS, including insights on (1) the specific activity of MCH neurons during PS; (2) how they might be controlled across the sleep–wake cycle; (3) how they might modulate PS; (4) and finally whether MCH might take part in the expression of some symptoms observed in primary sleep disorders.     

A multiparallel bioreactor for the cultivation of mammalian cells in a 3D‐ceramic matrix

For adherently growing cells, cultivation is limited by the provided growth surface. Excellent surface‐to‐volume ratios are found in highly porous matrices, which have to face the challenge of nutrient supply inside the matrices' caverns. Therefore, perfusion strategies are recommended which often have to deal with the need of developing an encompassing bioreactor periphery. We present a modular bioreactor system based on a porous ceramic matrix that enables the supply of cells with oxygen and nutrients by perfusion. The present version of the reactor system focuses on simple testing of various inoculation and operation modes. Moreover, it can be used to efficiently test different foam structures. Protocols are given to set‐up the system together with handling procedures for long‐time cultivation of a CHO cell line. Experimental results confirm vital growth of cells inside the matrices' caverns. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

PKA-mediated effect of MAS receptor in counteracting angiotensin II-stimulated renal Na-ATPase

We showed previously that angiotensin-(1-7) [Ang-(1-7)] reversed stimulation of proximal tubule Na⁺-ATPase promoted by angiotensin II (Ang II) through a d-ala⁷-Ang-(1-7) (A779)-sensitive receptor. Here we investigated the signaling pathway coupled to this receptor. According to our data, Ang-(1-7) produces a MAS-mediated reversal of Ang II-stimulated Na⁺-ATPase by a Gs/PKA pathway because: (1) the Ang-(1-7) effect is reversed by GDPβS, an inhibitor of trimeric G protein and Gs polyclonal antibody. Cholera toxin, an activator of Gs protein, mimicked it; (2) in the presence of Ang II, Ang-(1-7) increased the PKA activity 10-fold; (3) the peptide inhibitor of PKA blocked the Ang-(1-7) effect on Ang II-stimulated Na⁺-ATPase; (4) Ang-(1-7) reverses the Ang II-stimulated PKC activity; (5) cAMP mimicked the Ang-(1-7) effect on the Ang II-stimulated Na⁺-ATPase. Our results provide new understanding about the signaling mechanisms coupled to MAS receptor-mediated renal Ang-(1-7) effects.