Electrical behaviour in a line of anterior pituitary cells (GH cells) and the influence of the hypothalamic peptide, thyrotrophin releasing factor

Anterior pituitary cells of the GH line, which secrete prolactin spontaneously, showed spontaneous action potential activity. Thyrotrophin releasing factor, which increases secretion in these cells, caused a prompt increase of action potential frequency. Potassium, another secretagogue, depolarized the cells and sometimes initiated a burst of action potentials at the onset of this effect. The action potentials persisted in tetrodotoxin-containing and Na-free media, but were suppressed by the Ca-channel blocker, methoxyverapamil. Moreover, elevating the extracellular Ca²⁺ concentration increased the amplitude of the action potentials. These action potentials therefore have a prominent Ca component. This endows them with a particular interest since secretory activity of these cells is known to be dependent on extracellular Ca²⁺. Ba²⁺, which can substitute for Ca²⁺ in maintaining secretion, also substituted for Ca²⁺ in the maintenance of the action potentials. In addition, Ba²⁺ prolonged action potentials remarkably: tetraethylammonium was less effective in this regard.The several parallels between known secretory behaviour and electrical phenomena encourage the view that analysis of electrical activity in anterior pituitary cells may provide useful clues to events involved in stimulus-secretion coupling and in the secretory control exerted by the brain.     

A Simple Method for Isolation of Cardiomyocytes from Adult Rat Heart

A simple, economic, and sparing method for isolation of cardiomyocytes from adult rat heart is proposed. Ultrastructure of cardiomyocytes from suspension of freshly isolated cells was studied by light and transmission electron microscopy. The isolated cardiomyocytes were viable, had characteristic shape and size, and retained their normal structure. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 9, pp. 357–360, September, 2005     

Fast measurement of the CO2 partial pressure in gases and fluids

A CO₂-electrode system consisting of a membrane covered pH electrode, an electronic antilog modul and a special electronic analog circuit is described. Since the electrode output signal is a logarithmic function of the CO₂ partial pressure the output signal of the antilog module is proportional to the CO₂ partial pressure. The time course of the electrode signal has been analyzed after a step change of . This step response may be approximated by a sum of three exponential functions. Knowing the dynamic behaviour, the transfer function is formulated mathematically and a special analog circuit is constructed with a frequency response inverse to the frequency response of the electrode. Using this device the response time (T ₉₅) of the electrode system is diminished from 11,5 s to 750 ms after a step change of in gas (Luttmann, et al., 1974). If the time for the hydration of CO₂ is decreased by the addition of carbonic anhydrase the response time of the electrode is diminished to 6.5 s. Using the analog circuit yields a response time of 200 ms.Further studies were made to analyze the transient response in fluids at various flow velocities and various mountings. In order to analyze the influence of the fluid boundary layer on the surface of the electrode a photometric method has been developed (Luttmann and Mückenhoff, 1975), which allows to estimate the time course of the CO₂ partial pressure independently of and simultaneously with the electrode measurement.The experimental data are compared with a theory based on theoretical considerations of Schuler and Kreuzer (1967) and Crank (1956).List of Symbols A _i gain factor of thei-th compartment - A _i gain factor of the simulation network - C _i capacity - D diffusion coefficient - d electrode diameter - fraction of CO₂ - F _c (j) frequency response of the linearizing network - F _g (j) frequency response of the boundary layer - F _M (j) frequency response of the measuring system - F _M frequency response of the simulation network - I _i impedance transformer - j Gauss number (j ²=–1) - (j) frequency function of the CO₂ partial pressure - (t) time function of the CO₂ partial pressure - R _i electrical resistance - T _i time constant of the electrode - T _i time constant of the simulation network - T ₉₅ time for reaching 95% of the total difference - V voltage gain factor - v velocity of the streaming fluid - x coordinate - x(t) time function - X(j) corresponding frequency function - dilution factor - inverse time constant - thickness of boundary layer - ^* kinematic viscosity - thickness of diffusion layer - radian frequency Supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 114 (Bionach)     

The regional distribution and cellular localization of iron in the rat brain

The regional distribution and cellular localization of iron throughout the rat brain was determined with iron histochemistry. Densitometry was used to measure the intensity of stain of 51 iron-concentrating sites. Among the areas of highest iron content are the circumventricular organs, islands of Calleja, globus pallidus, ventral pallidum, substantia nigra pars reticulata, interpeduncular nucleus, dentate nucleus, and interpositus nucleus. Iron occurs most commonly in oligodendrocytes and in the fibrous network of the neuropil, but is also found in the interstitial spaces of circumventricular organs and in the tanycytes of the organum vasculosum of the lamina terminalis, median eminence, and walls of the third ventricle. In diverse areas throughout the brain—among them, the islands of Calleja, dentate gyrus of the hippocampal formation, lateral septal nucleus, and central amygdala—iron is found in association with the perikarya and neuronal processes of nerve cells.The overlapping distribution patterns of iron and γ-aminobutyric acid, enkephalin, and luteinizing hormone-releasing hormone suggest that the distribution of iron is related to its association with the metabolism of one or more neurotransmitters or neuroactive compounds.     

一种新型18°×4扇形网织红细胞计数窥盘

目的研制一种新型18°×4扇形网织红细胞计数窥盘。方法使用安瓿刀在玻片上刻制,再与国际血液学标准化委员会(ICSH)推荐的Miller窥盘进行网织红细胞对比分析。结果新型网织红细胞计数窥盘和ICSH推荐的Miller窥盘的准确度是一致的,但新型网织红细胞计数窥盘的精密度显著优于ICSH推荐的Miller窥盘。其参考范围也与其他报道一致。结论新型网织红细胞计数窥盘做法简单,不需特殊设备,值得推广应用。     

Infrared spectroscopy: A new diagnostic tool in Alzheimer disease

Biological markers play an evolving role in the diagnosis of Alzheimer disease (AD). We compare conventional measurements of cerebrospinal fluid (CSF) tau and β-amyloid_1–42 proteins to a novel approach – Fourier transformed infrared (FT-IR) spectroscopy – a simple technique derived from chemical and physical sciences that characterizes intramolecular bonds. For automatic diagnostic analysis, we developed an artificial neural network (ANN). We examined 71 patients with a clinical diagnosis of AD and 66 controls. β-Amyloid_1–42 was decreased (sensitivity 80% and specificity 78%); tau was elevated (sensitivity 76% and specificity 88%) in CSF of AD patients. The combined tau/β-amyloid_1–42 quotient was able to distinguish healthy from diseased subjects with 99% sensitivity and 86% specificity. The ANN could separate FT-IR spectroscopy data with 88.5% sensitivity and 80% specificity. FT-IR spectroscopy proved to be cost-effective and simple to perform. Diagnostic sensitivity and specificity is in the range of CSF tau and β-amyloid_1–42 protein analysis. Larger sample numbers for ANN training and validation could increase diagnostic accuracy and thus prove to be a useful screening tool.     

Effect of megestrol caproate on the reproductive function of laboratory animals

In vivo experiments on rats and rabbits showed that megestrol caproate, a 17-alpha-hydroxyprogesterone derivative exhibits 10-fold higher gestagenic activity compared to progesterone and possesses no androgenic, anabolic, and estrogenic activities.     

Physicochemical properties of membranes and functional status of liver mitochondria in rats with an inherited capacity for increased radical formation

Liver mitochondria of inbred W/SSM rats with inherited increased radical formation reveal the following anomalies: inhibition of oxidative phosphorylation, a lowered transmembrane potential, and alterations in protein-lipid interaction. The membrane viscosity and osmotic stability of mitochondria are unaffected. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 628–631, June, 1995