Electrical stimulation of the median eminence in rats,changes in catecholamine content and in plasma prolactin and growth hormone concentrations

Effects of field stimulation of the medial basal hypothalamus (MBH) and coaxial stimulation of the median eminence was studied on the catecholamine and DOPAC levels of the median eminence and on the prolactin and growth hormone release. The field stimulation induced an increased prolactin and growth hormone secretion without altering the catecholamine and DOPAC level. The direct electrical stimulation of the median eminence reduced the noradrenaline and dopamine content without significant changes in DOPAC concentration and in hormone secretions. It is concluded that (1) variations of DOPAC content are inadequate indicators of neuronal activity in the median eminence; (2) the multiple interaction of the stimulated neurons in the median eminence may mask the expected biochemical and hormonal responses to electrical stimulation.     

Adrenergic and dopaminergic regulation of circulating beta-endorphin-like immunoreactivity in hypertension.

The central alpha-2-adrenergic receptor agonist, clonidine (300 micrograms daily) significantly increased the plasma beta-endorphin-like immunoreactivity (beta ELI) in 12 patients with mild to moderate essential hypertension in a randomized, crossover study. A significant linear correlation between the increase in plasma beta ELI and the decrease in blood pressure (both systolic and diastolic) was found after clonidine administration. The role of the reduced central sympathetic tone, induced by alpha-2-adrenoceptor stimulation, in the elevation of circulating beta ELI can be suggested. The plasma beta ELI increased also significantly after the dopaminergic D-2 receptor agonist, bromocryptine treatment, (5 mg, daily) in 13 patients with borderline and mild essential hypertension in a randomized, crossover study. A significant drop in circulating noradrenaline and in arterial blood pressure and a significant linear correlation between the changes of plasma noradrenaline level and blood pressure was found after bromocryptine administration. There was no correlation between the rise in plasma beta ELI and the decrease in blood pressure after bromocryptine. The importance of the central sympathetic activity and not only a direct pituitary dopaminergic agonist effect on the beta-endorphin secretion can be stressed in the effect of bromocryptine on the immunoreactive beta-endorphin level.     

Skeletal muscle biopsy studies of cardiac patients

Eleven patients diagnosed and treated for congestive cardiomyopathy (COCM) of unknown aetiology, and another 10 patients, with congestive alcoholic heart muscle disease (ACOCM) were studied. Muscle biopsy samples were obtained from the vastus lateralis (VL) and the gastrocnemius (G) muscles. In part of the sample muscle the fibre pattern was classified by means of ATPase activity staining, a technique based on the pH lability of the fibres concerned. Fibre typing and area measurements were carried out by light microscope. The other part of the sample was used as muscle homogenate of which the Ca2+-activated ATPase activity as well as citrate synthetase (CS) and aldolase activities were measured. No significant difference was found in these enzyme activities between the two groups of patients. The proportion of the slow twitch (ST) fibres in the VL, mainly in the patients with ACOCM, was lower as compared to data for healthy subjects. A similar tendency was revealed for G. In both muscles tested, the area of ST fibres was smaller in the ACOCM group. The fast twitch (FT) fibre area proved to be slightly different in the two groups of subjects tested. Occurrence of degenerative signs in the histological tests was higher in the ACOCM than in the COCM group. It was concluded that differences in the skeletal muscles of patients with ACOCM and COCM may primarily account for the alcoholism. The disease of the heart muscle has little effect on the function of skeletal muscle. Even so, a low amount or lack of physical activity may have an unfavourable influence on the skeletal muscles of patients with heart muscle disease.     

Iron-Binding Compounds Produced by Wood-Decaying Basidiomycetes

The chrome azurol-S universal siderophore assay and the rapid paper electrophoresis siderophore assay were used to screen 10 wood-decaying basidiomycete isolates for the formation of iron-chelating compounds. All 10 isolates were positive for chrome azurol-S reactivity on solid plating medium and in liquid cultures, and 9 of the 10 isolates produced fluorescent iron-binding compounds in the paper electrophoresis assay.     

Influence of habitat characteristics on small mammals in a Mexican high-altitude grassland

Small mammals in a high-altitude grassland area close to Mexico City were studied. Populations of 10 species were censused using live traps in 48 sample quadrats. Within each quadrat, vegetation characterization, including complete floristic listings, cover values for species and layers and values of habitat modification, were assessed. Habitats were described according to plant communities identified using ordination and classification methods. Nine different plant communities were obtained. Densities and abundance of all small mammal species were calculated for each of the habitats classified. Peromyscus alsloni was the most abundant species in all habitats, reaching maximum densities of 55 ha⁻¹ in pine forest with dense ground and herb layer. Peromyscus melanotis also occurred in all habitats but at lower densities (maximum 29 ha⁻¹). Reithrodontomys megalotis was found in all habitats except in tall dense grassland. Densities for this species were generally low (1-9 ha⁻¹) but reached 19 ha⁻¹ in short dense grassland. All other species were largely absent from 4–8 habitats and showed very low densities (0.75–4 ha⁻¹). The densities of the more abundant species were largely correlated with more open habitats and higher indices of habitat modification. Lower altitude grassland habitats have a greater abundance of small mammals and a higher species richness than the medium and higher altitude, physiognomically more complex habitats. Species richness was highest in tall pine-alder forest with a species-rich, dense herb layer and lowest in pine forest with dense ground and herb layers. Species richness was positively correlated with overall small mammal density.     

High-frequency occurrence of virus-like particles with double-stranded RNA genome in Fusarium poae

Abstract Fifty-five geographically different strains of Fusarium poae were assayed for the presence of extrachromosomal nucleic acid elements. All strains were found to harbour double-stranded RNA (dsRNA) elements and encapsidated virus-like particles (VLP). There were great individual differences in dsRNA patterns of the various strains, but numbers and sizes characteristic for a given isolate remained unchanged after repeated subculturing of the fungi. Morphological alterations or signs of degeneration were not observed in dsRNA-containing isolates. This is the first report on the ubiquitous occurrence of dsRNAs in a hyphomycete fungus species.     

Long-term ACTH induced diminished responsiveness of prolactin secretion to morphine

The effect of morphine on plasma prolactin level and on dopamine turnover in the median eminence was studied using adult male rats chronically treated with ACTH. It was found that the ACTH pretreatment caused a decrease in the effect of morphine on prolactin secretion and prevented the inhibitory effect of morphine on dopamine turnover measured in the median eminence. The prolonged ACTH administration did not influence the prolactin content of the pituitaries and the in vitro dopamine sensitivity of lactotroph cells. Acute dexamethasone injection did not change the morphine-caused prolactin release. These results suggest that chronic ACTH treatment (possibly via corticosterone hyperproduction) elicits an opiate-tolerance like state of tuberoinfundibular dopaminergic neurons.     

Transthoracic needle aspiration biopsy in Wegener's granulomatosis. Morphologic findings in five cases

Percutaneous needle aspiration biopsies of the lung from five patients with Wegener's granulomatosis were reviewed. Three of the patients presented with the generalized form of the disease while two presented with the limited pulmonary form; one of the latter subsequently developed disseminated disease. The morphologic findings in the pulmonary aspirates were similar in all cases. The cytologic preparations contained neutrophils entrapped within necrotic debris plus scattered but prominent histiocytic giant cells, which often had nuclei arranged in rings or horseshoes, in a background of lymphocytes, epithelioid histiocytes and reactive pneumocytes. Cell block preparations showed discrete areas of necrosis containing a neutrophilic infiltrate and focally palisaded by epithelioid histiocytes. The intervening viable tissue contained prominent histiocytic giant cells and chronic inflammatory cells enmeshed in a fibrous matrix. One cell block contained a small artery with a small focus of possible granulomatous arteritis. While an open lung biopsy is generally required for a definitive diagnosis, the pathologist may encounter unsuspected Wegener's granulomatosis in a needle aspirate. Recognition of the findings observed in these cases should alert the pathologist to the possibility of Wegener's granulomatosis so that an open lung biopsy can be performed if clinically indicated and cytotoxic therapy can be promptly instituted if the diagnosis of this entity is confirmed.