Development of action potentials and apamin-sensitive after-potentials in mouse vestibular nucleus neurones

The postnatal maturation of medial vestibular nucleus (MVN) neurones was examined in slices of the dorsal brainstem prepared from balb/c mice at specific stages during the first postnatal month. Using spike-shape averaging to analyse the intracellularly recorded action potentials and after-hyperpolarisations (AHPs) in each cell, all the MVN neurones recorded in the young adult (postnatal day 30; P30) mouse were shown to have either a single deep AHP (type A cells), or an early fast and a delayed slow AHP (type B cells). The relative proportions of the two subtypes were similar to those in the young adult rat. At P5, all the MVN cells recorded showed immature forms of either the type A or the type B action potential shape. Immature type A cells had broad spontaneous spikes, and the characteristic single AHP was small in amplitude. Immature type B cells had somewhat narrower spontaneous spikes that were followed by a delayed, apamin-sensitive AHP. The delayed AHP was separated from the repolarisation phase of the spike by a period of isopotentiality. Over the period P10–P15, the mean resting potentials of the MVN cells became more negative, their action potential fall-times became shorter, the single AHP in type A cells became deeper, and the early fast AHP appeared in type B cells. Until P15 cells of varying degrees of electrophysiological maturity were found in the MVN but by P30 all MVN cells recorded were typical adult type A or type B cells. Exposure to the selective blocker of SK-type Ca-activated K channels, apamin (0.3 μM), induced depolarising plateaux and burst firing in immature type B cells at rest. The duration of the apamin-induced bursts and the spike frequency during the bursts were reduced but not abolished after blockade of Ca channels in Ca-free artificial cerebrospinal fluid containing Cd²⁺. By contrast, in mature type B cells at rest apamin selectively abolished the delayed slow AHP but did not induce bursting activity. Apamin had no effect on the action potential shape of immature type A cells. These data show that the apamin-sensitive I _AHP is one of the first ionic conductances to appear in type B cells, and that it plays an important role in regulating the intrinsic rhythmicity and excitability of these cells. Received: 19 November 1996 / Accepted: 30 June 1997     

Effects of liver ischemia on degradation of different classes of hepatic proteins

The effects of liver ischemia on hepatic protein degradation were studied in rats. In one series of experiments degradation was measured in incubated liver slices as release of trichloroacetic acid soluble radioactivity from proteins prelabelled with L-(¹⁴C)-leucine during 4 h (short-lived proteins) or during 24 h (long-lived proteins). In another series of experiments protein degradation was determined in vivo by measuring decay of radioactivity in hepatic proteins prelabelled with (¹⁴C)-sodium bicarbonate administered intraperitoneally 4 h or 24 h before induction of liver ischemia. Degradation of short-lived proteins was reduced by 50% both in vitro and in vivo during liver ischemia while breakdown of long-lived proteins was unchanged. Thus, short-lived and long-lived proteins were differently affected by liver ischemia. These results are consistent with the concept of distinct proteolytic pathways for different classes of proteins.     

男性抗精子抗体对体外受精一胚胎移植的影响

目的;评价男性抗精子抗体对体外受精-胚胎移植(IVF-ET)的影响。方法:以ELISA方法测定施行IVF-ET的150对不育夫妇中男方精浆抗精子抗体(AsAb)并分组:AsAb阳性组22例,AsAb阴性组128例。对比分析抗精子抗体及抗体类型对体外受精、卵裂和早期胚胎发育的影响,同时对移植后的妊娠率和流产率进行分析。结果:AsAb阳性组体外受精数明显低于AsAb阴性组(P<0.01),两组的卵裂数则无明显差异(P>0.05),而在阳性组中,不同抗体类型间体外受精、卵裂及胚胎质量无明显差异(P>0.05)。在移植日,AsAb阳性组的I级胚胎较阴性组低,而ⅢⅣ级胚胎和2原核受精细胞(2PN)明显增加(P<0.01)。两组移植后临床妊娠流产率无显著差异(P>0.05)。结论:AsAb能明显降低精子体外受精能力,对早期胚胎发育有损害。精子体处理不能完全清除AsAb对IVF影响。     

Biosynthetic reactions and ultrastructure of urothelial cells in chronic cystitis and cystopathies

A new form of morphogenesis of pathological process, cystopathy, was distinguished on the basis endoscopy data and morphofunctional analysis of the urinary bladder in chronic cystitis. Cystopathy is characterized by predominance of diffuse degeneration and atrophy of the urothelium, stromal sclerosis, absence of inflammatory cell infiltration, and inhibition of biosynthetic reactions in urothelial cells (compared to chronic cystitis). Cystopathy results from regeneratory and plastic failure. Instability of the bladder epithelium can be a morphological marker of oncological risk.     

The radioimmunoassay of histamine release from circulating basophils in an in vitro study as support for the in vivo active systemic anaphylaxis test in the guinea pig

An in vitro anaphylaxis test is described which explores the ability of compound re-challenge to induce histamine release from polynuclear basophils in whole blood of guinea pigs that had previously been sensitised. This test is used in drug safety, in support of the in vivo active systemic anaphylaxis test, which is sometimes required by regulatory authorities, when the observed clinical signs are not conclusive. This sensitive and discriminative test is inexpensive and reduces animal utilisation.     

Regulatory effects of osteoprotegerin on cellular and humoral immune responses

The interaction between receptor activator of nuclear factor-kappaB ligand (RANKL) and RANK has been reported to regulate immunity in addition to bone metabolism. The aim of this study was to determine if osteoprotegerin (OPG), an inhibitor of the RANKL-RANK interaction and possibly a new drug against osteoporosis, would adversely affect immunity. OPG was used to treat mice developing different models of cellular and humoral immune responses and also in vitro in T and B cell assays. In mice, OPG does not affect cell-mediated reactions such as contact hypersensitivity to the hapten oxazolone and liver damage, granuloma formation, and infectious load induced by mycobacterial infection. However, OPG increases humoral reactions such as the production of IgM, IgG, and IgE against the T cell dependent antigen keyhole limpet hemocyanin and the production of IgM against the T cell independent antigen Pneumovax. In vitro, OPG modestly co-stimulates T cells but does not affect the proliferation of B cells. OPG has modest immunoregulatory effects that seem to be confined to the humoral response to specific antigens.     

Histamine excites GABAergic cells in the rat substantia nigra and ventral tegmental area in vitro

We have investigated the effect of histamine (HA) on spontaneous firing of dopaminergic (DA) and GABAergic neurons in the substantia nigra (SN) and the ventral tegmental area (VTA) of the rat in vitro. Single-unit extracellular recordings were obtained and drugs were bath applied. In both regions application of HA (10 and 100 μM) did not affect the firing frequency of DAergic cells, but increased the firing of GABAergic neurons. The histamine-induced excitation was blocked by the H₁ receptor antagonist mepyramine (1 μM), but was unaffected by application of the H₂ antagonist cimetidine (50 μM) or the H₃ antagonist thioperamide (10 μM). Our results suggest that histamine does not directly inhibit dopaminergic neurons in SN and VTA, but rather that this inhibition is mediated through histamine-induced excitation of GABAergic neurons.     

Reactivity of a monoclonal antibody produced to the histidine-rich protein of Plasmodium lophurae with Plasmodium falciparum

Monoclonal antibodies were produced against the histidine-rich protein of Plasmodium lophurae and tested for reactivity with Plasmodium falciparum antigens. One anti-histidine-rich protein monoclonal antibody showed immunological cross-reactivity with polypeptides of P. falciparum synthesized in vivo and in vitro.     

A quantitative method for thein vitro study of sounds produced by prosthetic aortic heart valves Part II: an experimental,comparative study of the sounds produced by a normal and simulated-abnormal Starr-Edwards series 2400 aortic prosthesis

A comparative study was made of the sounds produced by a normal Starr-Edwards 2400 aortic valve prosthesis with those produced by the same valve but having a simulated overgrowth at the apex of the struts. Comparisons were made over the entire cardiac cycle for time and amplitude, power-density spectra, power-distribution spectra, power-distribution surfaces associated with individual valves, and three-dimensional power-distribution-difference surface. Power-density spectra were compared for portions of the cycle corresponding to the opening, systolic, and closing sounds of the valve. Physical parameters of an acoustical model were estimated from the power-density spectra. The results showed that each comparison gave information pertinent to the simulated malfunction. Opening. systolic and closing sounds, respectively, were different for each valve. The opening sound of the abnormal valve displayed a much lower frequency. Systolic sounds for the two valves were similar in frequency, but the normal valve produced more total power for this sound. The closing sound of the abnormal valve occurred later than that of the normal valve. These differences were more clearly seen when viewed in the frequency domain.     

钾离子对体外培养中枢神经髓鞘形成的影响──一种新的体外培养中枢神经脱髓鞘模型的建立

本文应用组织培养和电镜等方法研究了ＫＣＩ对体外培养中枢神经系统髓鞘形成的影响。结果表明：体外培养Ｂ６Ｃ３小鼠小脑组织髓鞘形成的关键期是１０～１４ｄ，在１０～１２ｄ时体外培养的小脑组织对ＫＣＩ最为敏感；当培养液内ＫＣＩ浓度达到３０ｍｍｏｌ／Ｌ时，即可完全抑制髓鞘形成。本文对钾离子引起体外培养中枢神经组织脱髓鞘的机制进行了讨论。