Characterization of spontaneous and decalin-induced hyaline droplets in kidneys of adult male rats

Studies were conducted to gain additional information about the spontaneous and decalin-exacerbated formation of hyaline droplets within the cytoplasm of proximal convoluted tubule (PCT) epithelial cells of the adult male rat. Renal cortical tissue protein patterns determined through two-dimensional gel electrophoresis revealed four species of a low-molecular-weight protein (18,000-20,000 daltons). Treatment groups differed only with respect to this protein, the relative concentrations of which paralleled the numbers of hyaline droplets in mature treated and untreated male rats. The increase in the numbers of hyaline droplets and protein accumulation were dose related. Neither this protein or hyaline droplets were detected in the renal cortical tissues of untreated or decalin-exposed adult female or immature male control rats. However this protein, and hyaline droplet formation, could be induced in the kidneys of adult, ovariectomized female rats by repeated testosterone injections. This protein was then demonstrated to be immunologically identical to alpha 2u-globulin, a protein synthesized by hepatic parenchymal cells. Alpha 2u-globulin protein has also been shown to be the major urinary component responsible for the proteinuria routinely observed in normal control adult male rats. PCT epithelial cell reabsorption and lysosomal accumulation of alpha 2u-globulin, reflected morphologically as hyaline droplets, occurs spontaneously only in the mature male rat. Decalin, a model compound, exacerbates this accumulation as a specific integral step in the pathogenesis of the nephropathy induced in male rats by volatile hydrocarbons. Hence, since men and women lack this specific PCT cell peculiarity, they would not be expected to respond to decalin exposure in a manner similar to the male rat.     

Orientation bias of neurons in the lateral geniculate nucleus of macaque monkeys

The purpose of this investigation was to analyze the influence of stimulus orientation on the responses of individual neurons in the monkey's lateral geniculate nucleus (LGN). Our specific goals were to assess the prevalence and the degree of orientation tuning in the monkey LGN and to determine if the preferred stimulus orientations of LGN neurons varied as a function of receptive-field position. The primary motivation for this research was to gain insight into the receptive-field configuration of LGN neurons and consequently into the neural mechanisms which determine the spatial organization of LGN receptive fields in primates. In both the parvocellular and magnocellular layers, the responses of the majority of individual neurons to sine-wave gratings varied as a function of stimulus orientation. The influence of stimulus orientation was, however, highly dependent on the spatial characteristics of the stimulus; the greatest degree of orientation bias was observed for spatial frequencies higher than the cell's optimal spatial frequency. On a population basis, the degree of orientation bias was similar for all major classes of LGN neurons (e.g. ON vs. OFF center; parvocellular vs. magnocellular) and did not vary systematically with receptive-field eccentricity. At a given receptive-field location, LGN neurons, particularly cells in the parvocellular laminae, tended to prefer either radially oriented stimuli or stimuli oriented more horizontally than their polar axis. Our analyses of the orientation-dependent changes in spatial-frequency response functions, which was based on the Soodak et al., (1987; Soodak, 1986) two-dimensional, difference-of-Gaussian receptive-field model, suggested that the orientation bias in LGN neurons was due to an elongation of the receptive-field center mechanism which in some cases appeared to consist of multiple subunits. Direct comparisons of the orientation-tuning characteristics of LGN cells and their retinal inputs (S potentials) indicated that the orientation bias in the monkey LGN reflects primarily the functional properties of individual retinal ganglion cells. We conclude that orientation sensitivity is a significant property of subcortical neurons in the primate's geniculo-cortical pathway.     

Nimodipine decreases resuscitability in a cardiopulmonary arrest model in the rat.

Although calcium has been implicated in ischemia-induced brain death or dysfunction, many animal studies do not show a beneficial effect of calcium-entry blockers given after resuscitation from a cardiopulmonary arrest (CPA). This may be due to the fact that treatment was started too late; we, therefore, evaluated the effect of the calcium-entry blocker nimodipine administered at the earliest feasible postischemic moment, i.e. at the start of the resuscitation attempts. In anesthetized Wistar rats, CPA was induced by an intra-cardiac injection of KCl, and maintained for 7 min by chest restriction. At the start of the resuscitation attempts, 50 rats were blindly and randomly assigned to intravenous treatment with either nimodipine (10 micrograms/kg over 2 min, followed by 1 micrograms/kg per min for 60 min; n = 25) or saline (n = 25). In the nimodipine group, significantly less rats could be resuscitated (11/25 versus 20/25) and the survival rate at the end of the 7 days evaluation period tended to be lower (5/25 versus 11/25). In the rats surviving after 7 days, there was no difference between both groups in incidence of seizures, neurological status and histological lesions in the hippocampus. It is concluded that nimodipine, in the dose tested and given during resuscitation in this rat model, has a detrimental effect on resuscitability and no beneficial effect on the neurological outcome in the surviving animals.     

Analysis of action potentials of muscles by a small general purpose computer (author's transl)]

To measure the duration of action potentials by a computer, the following steps are necessary: 1. automatic selection of suitable potentials from the EMG 2. identification of equal potentials (action potentials of the single motor unit) 3. measuring the durations of potentials, defined by the distance between first and last deviation from the base line. We noticed that the automatic evaluation of durations of single potentials is greatly deteriorated by base-line fluctuations. Therefore we average about 16 action potentials, stored in the computer, of the same single motor unit and measure the duration of the averaged potential.     

Gianotti-Crosti Syndrome Associated with Epstein-Barr Virus Infection

Abstract: Gianotti-Crosti syndrome (GCS) is a distinct exanthematic, acrolocated eruption of childhood caused by a variety of infectious agents. Historically hepatitis B antigen positive (HBsAG+) papular acrodermatitis of childhood and HBsAg negative (HBsAg-) papulovesicular acrolocated syndrome have been distinguished. Here we characterize the spectrum of associated infectious agents in seven patients with confirmed GCS seen in our departments in the years 1994–1995. Where available, stored frozen serum samples were reanalyzed for antiviral antibodies. The mean age of the two girls and five boys was 22.5 months with a range of 8 to 53 months. None of the patients was HBsAG+. Four patients showed serologic evidence of an acute infection and one patient of a recent Epstein-Barr virus (EBV) infection. In two additional children vaccination preceded the appearance of GCS. In these two patients serologic investigations revealed no evidence of recent infection with most common viruses. Our results underline the role of viral infections other than hepatitis B in the etiology of GCS. EBV infection was the most commonly associated viral disease in our population. We agree with other authors that we should avoid using the terms papular acrodermatitis of childhood and papulovesicular acrolocated syndrome in describing HBsAg+ and HBsAg- forms of GCS.