Chromatographic and biologic analysis of ME and OVLT LHRH

The luteinizing hormone (LH)-releasing activities a pooled rat organum vasculosum lamina terminalis (OVLT) and median eminence (ME) tissues were evaluated for chromatographic and biologic similarity and compared to those of synthetic decapeptide LH-releasing hormone (LHRH). The LHRH detected in these extracts appeared similar chromatographically (Sephadex G-25) to synthetic LHRH. These extracts, as well as synthetic LHRH, were also capable of stimulating dose dependent gonadotropin release form cultures rat gonadotrophs. These findings suggest a physiological role of the LHRH present in the rat OVLT in the control of gonadotropin secretion.     

Fetal hypothalamic transplants in the third ventricle of the adult rat brain

Summary Blocks of anterior hypothalamus were transplanted from 19 day-old fetuses of Wistar/Lewis rats into the third ventricle of adult male Brattleboro rats. Physiological changes in graft recipients and in sham-operated animals were monitored daily. Twenty days after surgery, the graft recipients and shamoperated animals were killed and their brains examined by correlative scanning and transmission electron microscopy. Host animals that exhibited both decreased polydipsia and increased urine concentration were found to have viable grafts within the third ventricle. The observed physiological changes suggested that synthesis and release of vasopressin occurred in the transplanted neurons. Grafts were well vascularized by vessels arising from the host hypothalamus. Neurons, with perikarya ranging from 8 to 30 m in diameter, glial cells, and neurites were located throughout the transplants. A neurohemal contact zone, similar to that normally seen in the median eminence, could not be demonstrated in the grafts. The absence of complete glial and ependymal barriers indicates a relatively close association between cells in the transplants and the cerebrospinal fluid. A large increase in supraependymal neurons and their processes, including an eruption of neurons through the floor of the third ventricle in one animal, was observed in graft recipients but not in shamoperated animals.Supported by NIH Grants NS 15109 and NS 13717     

Immunocytochemistry of luteinizing hormone releasing hormone (LHRH) in the sheep hypothalamus during various reproductive stages

Summary Using the labeled and unlabeled immunoperoxidase methods, the distribution and concentration (1) of immunoreactive LHRH-material in the hypothalamus, and (2) of gonadotropic hormones in the adenohypophysis of the ewe were determined during various reproductive stages, including two phases of the estrous cycle, anestrus, lactation, and the state after ovariectomy. The concentration of LHRH-immunoreactive material varied in particular regions of the median eminence (ME) and was closely dependent on the physiological state. The immunoreactive material was most abundant in hypothalami of lactating animals, exceeding gradually the corresponding deposits in ovariectomized animals, in ewes during the 16th day of the estrous cycle (before ovulation), and in anestrous ewes. A severe depletion of LHRH from the rostral and central parts of the ME was observed 24h after ovulation. This depletion was accompanied by a degranulation of LH-and prolactin-producing cells in the adenohypophysis. It is postulated that LHRH is stored in the ME of the sheep in all examined endocrine stages. Only circumscribed regions of the ME take part in the cyclic release of LHRH during the ovulatory phase; this suggests a functional differentiation of the nerve terminals in this neurohemal area.     

Effect of salt loading and salt deprivation on the vasopressin and oxytocin content of the median eminence and the neural lobe in adrenalectomized rats

Summary In adrenalectomized rats the influence of salt loading or salt deprivation on the vasopressin and oxytocin content of the median eminence (ME) and the neural lobe (NL) was studied by means of various methods: (1) morphometric and microphotometric analysis of aldehyde fuchsin-stained sections of ME and NL; (2) immunohistochemical demonstration of neurophysin, oxytocin, and vasopressin in the ME and in the NL; (3) radioimmunological measurement of oxytocin and vasopressin in the ME and in the NL. Adrenalectomy in salt-substituted rats raised the vasopressin content of the outer layer of the ME (OLME) but had no influence on the amount of vasopressin in the inner layer of the ME and in the NL. Osmotic stimulation of adrenalectomized rats by hypertonic saline markedly diminished vasopressin and oxytocin in the inner layer of the ME and in the NL but did not, or only slightly reduced vasopressin in the OLME. Withdrawal of salt supplementation in adrenalectomized rats resulted in a decrease of plasma sodium and plasma volume. It did not change the vasopressin or oxytocin content of the inner layer of the ME and of the NL, but it was correlated with a decrease of vasopressin in the OLME. The present findings may suggest that vasopressin in the OLME is involved in salt and/or volume regulation by influencing the hypophysial-adrenal axis.The study was supported by the Deutsche Forschungsgemeinschaft (Bo 392/6-5¹ and SFB 90, Cardiovasculäres System, A5²). The morphometric measurements with the TAS plus were carried out at the Max-Planck-Institut für Psychiatrie, Munich, FRG. We are particularly indebted to Prof. G. W. Kreutzberg and Prof. P. Schubert for their help     

The zinc iodide-osmium tetroxide (ZIO) reaction on nerve endings in the median eminence of the rat under normal and experimental conditions

Summary The reaction of nerve endings in the median eminence of the rat to zinc iodide-osmium tetroxide (ZIO) staining was examined electron microscopically under normal and experimental conditions. The experimental condition of catecholamine exhaustion in the nerve endings was induced by the administration of H44/68 and reserpine. Vesicles in the terminals of catecholaminergic nerves reacted similarly to ZIO staining in both normal and experimental material. The majority of synaptic vesicles in various terminals gave a positive ZIO reaction. The neurosecretory elementary granules, however, failed to react with ZIO. On the other hand, some nerve terminals in the external layer of the median eminence showed a strong positive reaction in the cytoplasmic matrix, in mitochondria as well as in synaptic vesicles. These findings strongly suggest that the ZIO-positive substance in nerve terminals is not the transmitter itself, i.e. the monoamine, but rather represents a range of substances commonly found in various kinds of synaptic vesicles and is probably proteinaceous in nature. A brief discussion is also given on the difference in ZIO reactivity between neurosecretory elementary granules and small vesicles in the hypothalamo-hypophyseal tract.This work was supported in part by a research grant from the Ministry of Education, Japan     

Quantitative radioautographic light and electron microscopic analysis of the localization of monoamines in the median eminence of the rat

Summary By means of light and electron microscopic radioautography a quantitative study of the regional distribution of catecholamines in the median eminence of the rat was carried out. One hour after intraventricular injection of ³H-dopamine the highest radioautographic reaction was recorded in the external zone, especially in the lateral palisade zone where many neurosecretory terminals are separated from the basal lamina of the portal pericapillary space by a glial cuff. This area showed the highest percentage (52%) of labelled catecholamine containing neurosecretory terminals as well as the maximal silver grain density per one terminal. In the medial palisade zone where direct neurovascular contacts with the capillary loops prevail, only 27 per cent of neurosecretory terminals were found to harbour tritiated dopamine. On the average 35 per cent of neurosecretory terminals in the median eminence of the rat contain catecholamines (both dopamine and noradrenaline). Pretreatment of animals with reserpine strongly reduced the binding of the label. Per cent of labelled neurosecretory terminals as well as grain density over terminals were decreased in both the medial and lateral palisade zones, although to a lesser degree in the latter. The site of origin of catecholamine fibers as well as the mode of catecholamine action at the level of the median eminence are discussed.This work was presented at the joint session of the Society of Anatomists, Histologists and Embryologists, the Society of Physiologists, and the Society of Neuroendocrinologists dedicated to the memory of Professor Wolfgang Bargmann, held in Leningrad, January 17, 1979It is a pleasure to express our deep gratitude to Prof. P.P. Rumyantzev and Dr. N.V. Seina of the Institute of Cytology of the USSR Academy of Sciences, Leningrad, for their valuable advice on electron microscopic radioautography     

The tanycyte of the rat median eminence

Summary The present ultrastructural study proves the existence of nerve terminals closely apposed to the plasmalemmata of tanycytes in the rat median eminence. Several of these axo-tanycytic endings display remarkable accumulations of agranular endoplasmic reticulum in the form of pleomorphic vesicles which are closely apposed on either side of the plasma membrane of each cell compartment. Some of these vesicular profiles give the impression of structural continuity across both membrane systems. This phenomenon is discussed in the context of being a potential substratum for communication between both cell compartments.Supported by NIH Grant NS13717 and NSF Grant BNS 78-11820     

A system of intraependymal cisternae along the margins of the median eminence in the rat: Structure,three-dimensional arrangement and ontogeny

Summary Structure, three-dimensional arrangement and ontogeny of large intracellular cisternae located in the median eminence region of the rat hypothalamus were studied using toluidin-blue stained semithin sections and electron microscopy. The cisternae occur along the projections of ependymal cells lining the ventral portion of the third ventricle (infundibular recess). Small cisternae can be seen close to the ventricle, whereas larger ones, divided into smaller compartments by thin septa, cluster near the surface of the hypothalamus. The cisternae are encompassed by a thin layer of cytoplasm to which axon terminals containing synaptic and dense core vesicles are closely related. Cisternae are arranged around the median eminence in a characteristic pattern. They occupy the midline in the retrochiasmatic area, flank both margins of the median eminence and extend caudally behind the origin of the pituitary stalk. The cisternae appear first between the 15th and 17th postnatal days. At about the 30th day their size and distribution resemble the situation observed in adult animals. The ependymal cisternae are suggested to be closely related to the luteinizing-hormone releasing-hormone (LH-RH)-containing fibers.     

射血分数保留的老年心力衰竭患者的临床特征

目的:分析和比较射血分数保留的心力衰竭(HFp EF)、射血分数中间值(HFmr EF)及射血分数降低的老年心力衰竭(HFr EF)患者临床特征的差异。方法:选取2017年9月至2018年8月哈尔滨市第一医院收治的老年慢性心力衰竭患者共287例,根据心动超声所测左室舒张末期内径(LVEF)值将其分为3组:HFpEF组175例、HFmr EF组50例和HFr EF组62例。比较各组患者一般情况、心动超声检查结果、血清学指标的差异。结果:(1)与HFr EF组患者比较,HFpEF组患者年龄、性别、吸烟史、体重指数(BMI)、原发冠心病、高血压、2型糖尿病患者比例、房颤发生率及心功能分级构成比均具有统计学差异(P0.05);(2)与HFr EF组相比较,HFpEF组患者的E/A比值,左房内径、肺动脉内径、LVEDD较小,而室间隔厚度较厚(P0.05);(3)与HFr EF组患者相比,HFpEF组血清总胆固醇、甘油三酯较高;血肌酐、血尿素氮、血尿酸、超敏C反应蛋白、N-末端脑钠肽前体水平较低,具有统计学差异(P0.05)。结论:老年HFpEF心力衰竭患者以女性居多,体重指数较大,以向心性肥胖为主,血压水平较高,心功能II级者比例高,有明显的舒张功能不全,易发生房性心律失常,房颤发生率高,主要病因为高血压。     

Median regression models for longitudinal data with dropouts

Summary .  Recently, median regression models have received increasing attention. When continuous responses follow a distribution that is quite different from a normal distribution, usual mean regression models may fail to produce efficient estimators whereas median regression models may perform satisfactorily. In this article, we discuss using median regression models to deal with longitudinal data with dropouts. Weighted estimating equations are proposed to estimate the median regression parameters for incomplete longitudinal data, where the weights are determined by modeling the dropout process. Consistency and the asymptotic distribution of the resultant estimators are established. The proposed method is used to analyze a longitudinal data set arising from a controlled trial of HIV disease ( Volberding et al., 1990 , The New England Journal of Medicine 322, 941–949). Simulation studies are conducted to assess the performance of the proposed method under various situations. An extension to estimation of the association parameters is outlined.