Phasically firing neurons in the supraoptic nucleus of the rat hypothalamus: immunocytochemical and electrophysiological studies

Relations between firing patterns and peptides in supraoptic neurons of rat hypothalamic slice preparations were studied by electrophysiology, intracellular fluorescent dye-marking and immunocytochemistry. Seven out of 10 magnocellular neurons which showed phasically firing patterns were identified by injections of Lucifer Yellow-CH (LY); these were also stained with an anti-vasopressin serum. This report presents direct evidence that most of the phasically firing neurosecretory neurons in the supraoptic nucleus contain vasopressin. This study demonstrates the feasibility of combining immunocytochemical and electrophysiological techniques to study the peptides contents of single mammalian neurons.     

Influence of pH and pCO2 on Alpha-Receptor Mediated Contraction in Brain Vessels

The response of isolated brain vessels to various pH levels or carbon dioxide tensions was analyzed. Reduction of the pH induced a slight relaxation of the vessel, whereas an increase in the pH produced a slight contraction. These effects were markedly exaggerated when the alpha-adrenergic receptors in the vascular wall were activated by noradrenaline. During these conditions the contractile response to noradrenaline was reduced by about 40 per cent at a pH of 7.01, while, on the other hand, the response was enhanced 3-fold at a pH of 7.80. Variations in carbon dioxide tension of the buffer solution between 16 mmHg and 64 mmHg produced no consistent change, provided the pH remained constant. The results indicate that an interaction between the perivascular pH and the adrenergic alpha-receptor mediated contraction in brain vessels may occur.     

Inflammatory cell infiltrate in a responding metastatic nodule after vaccine-based immunotherapy

A patient with von Hippel Lindau disease, bilateral symmetric renal cell carcinoma and pulmonary metastases treated with immunotherapy is the subject of this study. A left kidney and tumour mass were removed and the tumour cells used to make an autologous tumour/bacille Calmette–Guérin (BCG) vaccine as part of the treatment protocol. The patient's pulmonary nodules responded, but the remaining renal nodule subsequently grew. Samples of both tumours were obtained allowing for an internally controlled evaluation of the histological and immunohistologic differences between a responding and non-responding tumour nodule after therapy. The immunotherapy protocol is designed to promote a T cell response to autologous tumour. Cellular infiltrates were demonstrated in both responding and non-responding nodules compared with the pretreatment tumour specimen, but the responding nodule contained proportionately more T cells as well as markedly increased numbers of plasma cells and granulocytes. This suggested that several arms of the immune system may have been operative in the responding nodule.     

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     

Detection of Epstein-Barr virus in a case of undifferentiated nasopharyngeal carcinoma by in situ hybridization with digoxigenin-labelled PCR-generated probes

A case of nasopharyngeal carcinoma is presented. Epstein-Barr viral genome was identified in the neoplastic cells by in situ hybridization with digoxigeninlabelled polymerase chain reaction-generated probes. We report the development of this technique in paraffinembedded sections and propose that such identification may prove valuable for the diagnosis of this tumour in routine material.P. Delvenne is a research associate of the National Fund for Scientific Research (Belgium)     

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.     

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.