Effects of subchronic acrylamide treatment on the endocrine pancreas of juvenile male Wistar rats.

Acrylamide (AA) is a well-known industrial monomer with carcinogenic, mutagenic, neurotoxic and endocrine disruptive effects on living organisms. AA has been the subject of renewed interest owing to its presence in various food products. We investigated the potential adverse effects of oral AA treatment on the endocrine pancreas of juvenile rats using histochemical, immunohistochemical, stereological and biochemical methods. Thirty juvenile male Wistar rats were divided into one control and two AA treatment groups: one treated with 25 mg/kg AA and the other treated with 50 mg/kg AA for 21 days. We found a significant decrease in ß-cell mass. The significant decrease in ß-cell optical density and unchanged blood glucose levels indicate that normoglycemia in AA treated rats may result from intensive exocytosis of insulin-containing secretory granules. By contrast with ß-cells, we observed increased α-cell mass. The slight increase in α-cell cytoplasmic volume suggests retention of glucagon in α-cells, which is consistent with the significant increase in α-cell optical density for AA treated animals. The number of islets of Langerhans did not change significantly in AA treated groups. Our findings suggest that AA treatment causes decreased ß-cell mass and moderate α-cell mass increase in the islets of Langerhans of juvenile male Wistar rats.

Gill reaction to pollutants from the Tamis River in three freshwater fish species, Esox lucius L. 1758, Sander lucioperca (L. 1758) and Silurus glanis L. 1758: a comparative study.

The study evaluated the effects of waterborne pollutants from the Tamis River on gill histology and possible differences in gill reaction patterns between three freshwater fish species, pike Esox lucius L. 1758, pike-perch Sander lucioperca (L. 1758) and wels catfish Silurus glanis L. 1758 from the Tamis River. Gills from analysed fish species showed moderate to intense histopathological alterations. The most frequent progressive alteration was hyperplasia of epithelium, whereas the most frequent regressive alteration was epithelial lifting. Circulatory disturbances were most often manifested in the form of hyperaemia. During comparative analysis, differences in gill indices, reaction and alteration indices, as well as in gill and filament prevalence between analysed species, were observed. Although all analysed fish species did show both progressive and regressive alterations, there was a significant difference in the level of expression of these reaction patterns. Gill index obtained for pike clearly stands out as the lowest. Wels catfish showed the highest progressive reaction index, significantly higher in comparison with the other two species (P < 0.05), while pike-perch showed the highest regressive reaction index, also significantly higher in comparison with the other species (P < 0.001). These results may implicate species-specific gill reactions and thus present a useful tool for better understanding toxic mechanisms of various pollutants.

Evaluation of rat thyroid gland morphophysiological status after three months exposure to 50 Hz electromagnetic field.

Objective of our study was to use morphophysiological criteria in order to determine the sensitivity of male rat thyroid gland to an extremely low frequency electromagnetic field (ELF-EMF) influence and the ability of the gland to repair after period of exposure. Animals were exposed to 50Hz, 50-500 microT ELF-EMF for 3 months when a part of them (group I) were sacrificed, while the rest of animals were subjected to recovery evaluation of the gland and sacrificed after 1 (group II), 2 (group III) and 3 (group IV) weeks. Histological and stereological analyses were performed on paraffin and semifine thyroid gland sections. Serum T3 and T4 were also determined. Histological and stereological analyses showed that the volume density of follicular epithelium and thyroid activation index decreased, while the volume density of colloid and capillary network increased in group I, II and III. The values of all these parameters in group IV were similar to corresponding controls. Serum T3 and T4 concentrations were significantly lower in all exposed animals, except in group I. Results of this study demonstrate that after significant morphophysiological changes caused by ELF-EMF exposure thyroid gland recovered morphologically, but not physiologically, during the investigated repair period.

Morphophysiological status of rat thyroid gland after subchronic exposure to low frequency electromagnetic field.

The objective of this study was to examine the impact of low-frequency electromagnetic field on male rat thyroid gland of Mill Hill strain. Animals were exposed to 50 Hz frequency, of decaying intensity from 500 microT to 50 microT and 10 V/m field, beginning 24 hours after birth, 7 hours a day, 5 days a week during three months. Results of histological and stereological analysis showed increased volume density of thyroid follicles, decreased thickness of the follicular epithelium, intrafollicular colloid content in lumen, decreased thyroid activation index, increased volume density of parafollicular cells, decreased volume of interfollicular connective tissue and increased number of degranulated mast cells in exposed animals in regard to control animals. Radioimmunologic assays were used to examine thyroid hormone concentrations in the blood serum revealing decrease of the total T4 as well as of total T3 in animals exposed to electromagnetic field in regard to controls. The obtained results show that a three month-exposition of animals to low frequency electromagnetic field led to morphofunctional alterations of the thyroid gland that can be referred to as reduced activity of the gland.

[The hypophyseal-adrenal axis in chronic alcoholism]. / Hipofizo-adrenalna osovina u uslovima hronicne alkoholisanosti.

In order to reveal the morphologic basis of clinically recognized pseudo Cushing syndrome in chronic alcoholism, we performed an analysis of histologic characteristics of hypothalamo-hypophyseal adrenal axis components. The experiment included Wistar rats which were given 15% ethanol solution in water for three months. By methods of classical histology, histochemistry and immunofluorescence adrenal and hypophyseal sections of experimental animals exposed to continual effects of alcohol and those from the control group were examined. ACTH (adrenocorticotropin) cells of the experimental group show expressed immunofluorescence as a proof of their high secretory granules present in numerous cytoplasmic endings which contribute to significantly increased number of these cells comparing to the control group. In the adrenal cortex of animals exposed to alcohol, in the zona fasciculata and zona reticularis, under the influence of hypophyseal corticotropin (ACTH) secretion, there is a statistically significant increase of the compact cells region, as synthetic active elements, in regard to vacuolized cells, as inactive elements, which has been established stereologically. Simultaneous hyperfunction of hypophyseal ACTH cells and ACTH dependent zones of the adrenal cortex in chronic alcoholism, proves that alcohol primarily acts at the level of hypothalamus and hypophysis, while adrenals react to hypersecretion of ACTH cells. The way alcohol affects neurotransmitters is the topic of the discussion, whereas stimulated synthesis of acetylcholine is pointed out.

[Effects of ethanol on thyroid gland development]. / Efekat etanola na razvoj tireoidne zlezde.

Maternal ingestion of alcohol appears to cause a pattern of congenital anomalies with pre- and postnatal growth in the offspring. In order to study the possible implication of thyroid function in the effect of exposure to alcohol, we have studied structural alterations of this gland during early postnatal period (0-20 days) of the rats from alcohol-fed mother, which were given 15% ethanol as the only drinking solution daily one month before and during pregnancy and lactation. The results of the light-microscopic and stereological analysis clearly show that maternal ingestion of ethanol results in the stimulation off the thyroid gland of their pups. This was the most prominent in 20-day-old rats, what is substantiated by the much more irregular apical surface of the follicular cells, appearance numerous colloid droplets, significant increase both the volume density of follicular epithelium (p < 0.05) and interfollicular tissue (p < 0.001) and significant reduction in volume density of colloid (p < 0.001). These results suggest that maternal ethanol exposure disturbs the normal structure of the thyroid gland of their offspring what may, at least partly, mediate to alcohol-induced detrimental effect on growth and development in the fetus and neonate.

Fungal degradation of polyhydroxyalkanoates and a semiquantitative assay for screening their degradation by terrestrial fungi.

The current problems with decreasing fossile resources and increasing environmental pollution by petrochemical-based plastics have stimulated investigations to find biosynthetic materials which are also biodegradable. Bacterial reserve materials such as polyhydroxyalkanoates (PHA) have been discovered to possess thermoplastic properties and can be synthesized from renewable resources. Poly-beta-hydroxybutyric acid (PHB) is at present the most promising PHA; and BIOPOL, its copolymer with poly-beta-hydroxy-valerate (PHV), is already industrially produced (ICI, UK), and used as packaging material (WELLA, FRG). According to the literature, PHA degradation has so far mainly been observed in bacteria; only under certain environmental conditions has fungal degradation of PHAs been indicated. Since fungi constitute an important part of microbial populations participating in degradation processes, a simple screening method for fungal degradation of BIOPOL, a PHA-based plastic, was developed. Several media with about 150 fungal strains from different terrestrial environments and belonging to different systematic and ecological groups were used. PHA depolymerization was tested on three PHB-based media, each with 0.1% BIOPOL or PHB homopolymer causing turbidity of the medium. The media contained either a comparatively low or high content of organic carbon (beside PHA) or were based on mineral medium with PHA as the principal source of carbon. The degradation activity was detectable due to formation of a clear halo around the colony (Petri plates) or a clear zone under the colony (test tubes).(ABSTRACT TRUNCATED AT 250 WORDS)

[Reactive characteristics of the neurohypophysis in the early postnatal period]. / Reaktivna sposobnost neurohipofize u ranom postnatalnom periodu.

The maturity of the hypothalamic-neurohypophyseal system in the first 10 days of the postnatal life of rats was analysed through the potential inhibitory effect of ethanol on oxytocin and vasopressin secretion. Experimental animals were intraperitoneally injected with ethanol, and the control ones with the corresponding amount of physiological solution. Hypophyses were extracted 30 min later to be histologically analysed. Although the morphological features of neurohypophysis with functionally active pituicytes and dense vascular net were present even from the first natal day, neurosecretory grains were noticed not before the 8 th day. But the inhibitory effect of ethanol on neurosecretion did not manifest itself until the 10 th day, so it can be concluded that in this period the hypothalamic-neurohypophyseal system had not yet reached its level of complete maturity. Fatty acids in pituicytes being elements of neurohypophyseal neuroglia are pronunced even in animals younger than 10 days, which indicates that their origin could not be necessarily linked to the process of neurosecretion. In acutely alcoholized offsprings the amount of fatty acids in the neurohypophysis was reduced. This is substantiated by the engagement of the alcohol dehydrogenase (ADH) and the microsomal ethanol-oxidizing system (MEOS) in alcohol metabolism with which follows retarded oxidation process of fatty acids.

[Histological picture of the subcommissural organ in chronic alcoholism in rats]. / Histoloske odlike supkomisuralnog organa pacova u hronicnom alkoholizmu.

In the course of a three-month administration of 15% ethyl alcohol solution as the only liquor offered to the experimental rats, SCO characteristics were analysed by methods of light microscopy, and SCO height measurements and by measuring the volume of the ependymocyte nuclei. There was abundant vacuolization of individual ependymocytes, as well as in groups of them, and increased apical and subapical neurosecretory accumulations. The volume of the nucleus was significantly augmented, whereas the SCO height remained within the limits of the control values. The changes obtained corroborate the idea of an active engagement of the SCO in the course of chronic alcohol consumption by experimental rats.

[The effect of alcohol on the intermediate hypophyseal lobe in the early postnatal period]. / Srednji rezanj hipofize u ranom postnatalnom periodu pod uticajem alkohola.

Concerning the well known stimulative effect of ethanol on the secretory activity of the intermediary lobe of the hypophysis in mature animals, the effect of the same agent was analyzed in the young of the alcoholized parents. Immediately after animals were parted from their alcoholized breast feeding mothers the hypophyses of the young old 1, 10, 20 and 30 days were taken for hystological analysis. In the first day of postnatal life the intermediary lobe is completely developed so that it has a glandular tissue covered by marginal epithelium; but structural changes connected with the influence of alcohol were not noticed. In the young old 10 days, the initial hyperplasia of the gland cells in the intermediary lobe was noticed and intermediocytes penetrated deep into the posterior lobe area. Histological findings at the 20th and 30th day of life are similar and manifested through the prominent hyperplasia of the glandular cells and through the hyperfunction certified by a rich content of intermediocytes in the RNA and the intensified activity of succinate-dehydrogenase and NADH diaphorase at the level of the marginal epithelium. The fact that the intermediary lobe cells are not able to react on the alcohol stimulation before the 10th day of life could be explained by the immaturity of the neurotransmitter system.

[Histologic characteristics of the subfornical organ in rats during increases and decreases in the ambient temperature]. / Histoloske odlike subfornikalnog organa pacova u uslovima povisene i snizene temperature okoline.

The authors investigated characteristics of the rat subfornical organ as chronically affected by increased ambient temperature and under the conditions of intermittent hypoxic hypothermia. The histological and stereological parameters analysed point to a stimulated functioning of the rat subfornical organ under temperature stress.

A model for acid and alkaline phosphatase activity in a small pond.

Acid and alkaline phosphatase activity were determined in a small pond over a period of 24 months (64 samples). Activity of each phosphatase enzyme was positively correlated with chlorophyll concentration, viable bacterial count, total phosphate concentration, inorganic phosphate concentration, and temperature. Multiple regression analysis was used to formulate equations that described phosphatase activity in terms of these physical, chemical, and biotic factors. Corrected coefficients of determination were calculated, and the highest values were obtained when all parameters were included in the equation (r (2)=0.776 and 0.659 for alkaline and acid phosphatase activity, respectively). However, there was little improvement in ther (2) value obtained when only chlorophyll was used in the equation (r (2)=0.654 and 0.624, respectively). Samples were then taken over a further 12 months (25 samples), and observed activity was compared with the activity predicted by application of the previously derived equations. For alkaline phosphatase, the best fit between observed and expected activity was seen with the equation containing all parameters, but for acid phosphatase the best fit was seen with the equation containing only chlorophyll and temperature as the determinants. In both cases there was a good fit between observed and expected data using the equation containing chlorophyll as the sole determinant. From this we have concluded that phytoplankton were the chief producers of phosphatase activity in this pond, although the influence of physical and chemical factors on enzyme activity could not be ignored.