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Biomedical subjects

J E Bruni

Publications and source records attributed to J E Bruni.

At least 37 records · Page 2Linked to original sources
PubMed1986

Reaction of rabbit lateral periventricular tissue to shunt tubing implants.

The reaction of the periventricular tissue of the lateral ventricle to silicone rubber shunt tubing was studied by scanning and transmission electron microscopy. Nonfunctioning shunt tubing was implanted bilaterally into the frontal horns of rabbits, which were then sacrificed at postoperative intervals of 3 days to 16 weeks. Colchicine was used to study mitotic activity at the 3-day to 4-week postimplantation intervals. Reactive changes that occurred in the periventricular tissue correlated with the degree of contact with the implant and also with the duration of the postoperative period. Ependymal cells underwent progressive attenuation and sloughed completely in the most severely affected areas. Prominent gliosis in the subependyma accompanied the ependymal changes. The ventricular surface directly adjacent to holes in the implant developed ependyma-covered glial evaginations which grew into the implant holes beginning 1 week postimplantation. In the region of the outgrowths, ependymal mitotic activity was significantly increased at 1 and 2 weeks postimplantation. and astroglial mitotic activity was increased at 3 days and 1 week. Proliferation of ependymal and glial cells in the area touching the shunt tubing and mechanical factors contributed to the development of cellular outgrowths which may be a factor in the pathogenesis of shunt obstruction in human hydrocephalus.

Animals↗
PubMed1985

Ependyma: normal and pathological. A review of the literature.

A review of the available literature reveals that proliferation of ependyma occurs during embryological and early postnatal periods of development. Turnover, however, declines significantly during postnatal life and only low levels of residual activity persist into adulthood under normal conditions. In some regions of the ventricle, however, morphological and histochemical differentiation of ependyma is not attained for some considerable time postnatally. Recent immunocytochemical studies using GFAP indicate that only tanycytes may acquire antigenicity during development and that they may share a common phylogeny and/or function with astrocytes. Under pathological conditions, the bulk of available evidence suggests that inherent differences may exist in the proliferative capacity of ependyma in different regions of the neuraxis. Although the response of ependyma to various pathological conditions is equivocal, proliferation has been often observed in response to spinal cord injury. Indeed, ependyma is believed to play a significant role in the initiation and maintenance of the regenerative processes in the spinal cord of inframammalian vertebrates. In hydrocephalus there appears to be a remarkable similarity in cytopathological changes regardless of the mode of induction. The sequence, severity and extensiveness of damage appear to correlate with the degree of ventricular dilatation. The most commonly observed changes are (1) stretching and flattening of ependyma, most pronounced over white matter, (2) characteristic ependymal cell surface changes associated with ventricular distension, (3) increased extracellular space and periventricular edema and (4) demyelination and subependymal gliosis. Although ependymal cell proliferation has been reported as part of the overall tissue response to chronic hydrocephalus and to the pathology of ventricular shunt occlusion, the evidence is not entirely convincing and there is clearly a need for further research on the subject.

Animals↗
PubMed1985

Human neonatal hydrocephalus. An electron microscopic study of the periventricular tissue.

An infant of 43 weeks gestational age with severe congenital hydrocephalus was operated on for removal of a subependymal astrocytoma in the region of the foramen of Monro. A biopsy of periventricular tissue was taken from the lateral ventricle for examination by scanning and transmission electron microscopy. The ependyma was largely denuded, with glial cell processes forming most of the ventricular lining. Many of the attenuated ependymal cells, however, had intact junctional complexes at areas of contact with other ependymal cells. Club-shaped unipolar cells, believed to be a previously undescribed form of immature ependymal cells, were found in the ventricular lining. Cerebrospinal fluid edema was present in the neuropil up to 60 microns from the ventricular lumen, but there was no obvious axonal pathology in the tissues examined.

Cerebral Ventricles↗
PubMed1984

Cytoarchitecture of the rat's supraoptic nucleus.

There have been few Golgi studies dealing with the cytoarchitecture of the supraoptic nucleus (SON). This is due in part to resistance of supraoptic neurons to impregnation by Golgi methods. In this study, the structure of the SON was examined in normal S/D rats by using both Nissl and Golgi-silver methods. The purpose was to correlate shape, size and location of neurons within the SON as revealed by these two techniques. On the basis of size, neurons of the SON can be divided into 3 populations: greater than 200 micron2, (9%); 100-200 micron2, (64%); and less than 100 micron2, (27%). The larger neurons are located predominantly at mid-nuclear levels; the smaller at rostral and caudal levels of the nucleus. The perikarya of most SON neurons (64%) are only slightly elliptical in cross-section (L/W less than or equal to 2). The large neurons, however, tend to be more spherical whereas the smaller neurons are more elongated (L/W greater than or equal to 3). In Golgi preparations, a variety of randomly distributed bipolar and multipolar neurons were identified. One form of bipolar neuron had a large spherical or oval cell body that was intimately associated with blood vessels. Its thick, varicose dendrites usually lacked spines and were not extensively branched. A second form of bipolar neuron was distinguished by its smaller more fusiform cell body and lengthy dendrites which were often spinous and more extensively branched. Axons, when present emerged from the cell body or a proximal dendrite and were uniformly thin except for fusiform swellings along their length. Among multipolar neurons, the following variants were distinguished: spherical and polygonal neurons of various sizes with 3-5 dendrites and small triangular neurons with dendrites arising from each of the poles. The results of this study demonstrate the heterogeneity of the rat SON and of its neuronal components, some of which appear suited to function in a nonendocrine capacity, possibly as interneurons.

Animals↗
PubMed1984

Effect of D, L-alpha-aminoadipate on the mediobasal hypothalamus and endocrine function in the rat.

Using the glutamate analog, D,L-alpha-aminoadipic acid (D,L-alpha AA), experiments were conducted to examine the nature, extent, and specificity of its toxicity in the mediobasal hypothalamus and to determine its effect on endocrine homeostasis. Neonatal rats received daily injections of D,L-alpha AA (4 g/kg BW) on postnatal days 5-10 and were killed at various post-treatment intervals. Sex-matched littermates were given equimolar amounts of NaCl and served as controls. Treated rats killed 18 days post injection weighed slightly less than controls and had reduced testicular, ovarian, and uterine weights, but the differences were not statistically significant. In D,L-alpha AA treated rats serum and pituitary levels of TSH and PRL were comparable to control values. Pituitary content of LH (male's and female's) and FSH (female's), however, was lower (P less than 0.05) in D,L-alpha AA treated rats than in controls, but serum levels were not significantly different. Distinct cytopathologic changes were evident in the arcuate nucleus and median eminence of D,L-alpha AA-treated rats killed at 2 and 6 h post injection only. By 12 h evidence of acute damage had largely disappeared. Both glial and ependymal cells underwent edematous swelling and necrosis, but neurons were largely unaffected. Evidence of reactive changes, such as gliosis, infiltration of microglia, and removal of debris, however, were not very conspicious. A random sample of mediobasal hypothalami of rats killed 18 days post injection failed to show any detectable lesion or residual effects of earlier pathology. Age at the time of exposure to the gliotoxin was found to be an important variable affecting both extent and duration of injury. The most deleterious effects were observed when the gliotoxin was administered in the form of a single injection on postnatal day 5 only. The results suggest that normal neuronal activity and endocrine homeostasis, specifically gonadotropin, may be irreversibly altered as a consequence of transient disruption of the glial compartment.

2-Aminoadipic Acid↗
PubMed1983

Tanycyte ependymal cells in the third ventricle of young and adult rats: a Golgi study.

The structure and distribution of tanycytes within the ependymal lining of the third cerebral ventricle of young (3 week old) and adult (24 week old) rats was examined using a modified Golgi-silver method. In both age groups, 3 tanycyte forms were identified on the basis of differences in the morphology of their basal processes: Type 1 - with long (greater than or equal to 200 microns), non-spinous basal processes; Type 2 - with long (greater than 100 microns) basal processes, the proximal segment of which bear spine-like projections and Type 3 - with short, spinous basal processes. In addition, tanycytes of 3 week old rats exhibited features that distinguished them from their respective adult forms. In these rats: i) tanycyte somata are smaller, more regular in outline and often bear apical processes, ii) the basal processes of Type 1 and 2 tanycytes are smaller in diameter and are less tortuous in their course through the neuropil, iii) the terminal segments of many Type 1 tanycytes bear spiny projections and iv) the proximal segments of Type 2 tanycytes are less coarse in appearance and bear distinctive fine projections. Differences in the regional distribution of tanycytic forms within each age group are also provided. Collectively, these observations suggest that tanycytes in 3 week old rats have not fully acquired adult form and possibly function.

Aging↗
PubMed1983

Ependymal cells of the rat fourth ventricle: response to injury.

The response of ependyma to injury was investigated in rats following placement of bilateral lesions in the floor of the fourth ventricle. Animals were sacrificed from 2-60 days post-operatively and the brains were prepared in the conventional manner for comparative LM, SEM and TEM examination. For LM radioautography, randomly selected lesioned rats received either a single i.p. injection (5 muCi/g BW) or multiple injections (2 muCi/g) of 3H-thymidine prior to sacrifice. Focal disruption of the lining resulted in significant qualitative and quantitative changes in the ependyma at the wound margins. Labelling of normally quiescent ependymal cells occurred from day 2-6 post-operatively, however, the level of turnover was relatively low. Labelling was maximum on day 2 and was greater at the medial than lateral margin of the wound. During the first postoperative week, a gradual increase was observed in the number of ependymal cells per unit length at the margins of the wound concomitant with an abrupt reduction in wound diameter. This was consistent with the assumption that newly formed cells were added to the ependymal sheet at the leading edges of the wound. From 14-60 days after injury, further repair resulted from asymmetrical spreading and thinning of the ependymal sheet in the absence of mitotic activity. Quantitatively, this was reflected in a reduction in cell number at the leading edges of the wound that was most pronounced at the lateral margin. At day 60 neither epithelialization nor wound closure was complete and the normal architecture of the lining had not been fully restored. These results suggest that ependyma in the fourth ventricle of the postnatal rat undergoes a process of only limited repair following injury.

Animals↗
PubMed1982

Ovulation in the rabbit following intraventricular and intravenous administration of synthetic Gn-RH.

A comparison was made of the efficacy of intravenously (iv) and intraventricularly administered synthetic Gn-RH in inducing ovulation in conscious and urethane anaesthetized rabbits. Via the iv route of administration, the minimum dose of Gn-RH required to induce ovulation in all animals of the conscious group was 300 ng/kg body weight. This is in contrast to the larger systemic dose (400 ng/kg body weight) of Gn-RH required to achieve the same results in urethane anesthetized but otherwise identically treated rabbits. This suggests that although ovulation is no blocked by an anaesthetic dose of urethane (1.25 g/kg), the ovulatory response is altered in some way by the anaesthetic. When administered intraventricularly, the minimum dose of Gn-RH required to induce ovulation in anaesthetized animals was only 100 ng/kg body weight or 25% of the equivalent systemic dose. Systemically ineffective doses of Gn-RH (less than or equal to 200 ng/kg body weight) also induced ovulation in the anaesthetized group when administered via the third cerebral ventricle. All animals that ovulated did so between 13 and 16 h following Gn-RH administration and the number of ova recovered paralleled the number of ruptured follicles. A graded increase in the number of ova released with dosage of Gn-RH was not observed. In this study, the smaller defective dose requirement for intraventricularly administered decapeptide supports the view that Gn-RH in the CSF circumvents the general circulation and reaches the portal vasculature directly via the median eminence.

Animals↗
PubMed1978

[Gallbladder calculi: cholesterol concentration and its radiologic correlates].

Cholesterol concentration in the gallstones of 84 patients obtained by surgery is studied and radiologic correlation of the stones (lucency and opaqueness) is established with relation to cholesterol concentration. We conclude that 70% of gallstones in our population, contain greater than or equal to 80% of cholesterol and the radiographic appearance of stones in functioning gallbladder is a good method to predict cholesterol content in gallstones.

Adult↗
PubMed1978

[Bile lipid composition of cholecystectomized patients during fasting and in postprandial periods].

Fasting state, 1 and 3 hours postprandial biliary lipid periods are studied in 19 cholecystectomized gallstone patients. Methodological items togeher with the characteristics of the kind of diet: normocaloric; lipids, 15% (50% of which are obtained from animals); proteins, 25%; and carbohydrates, 60% are established. It is concluded that biliary lipids are not quantitatively modified in the subjects on established diet respect fasting, 1 and 3 hours postprandial periods, particularly pointing out that the biliary cholesterol saturation rate remains unchanged--supersaturated--for fasting state, as well as for postprandial periods. We believe that the lack of observable changes may be in relation with the characteristics of the employed diet, which is usually suggested to people suffering from cholecystopathies in Argentina.

Bile↗
PubMed1975

Neurosecretory activity within suprachiasmatic neurons of the female rabbit following castration.

The effects of ovariectomy on the ultrastructure of neurons within the SCH nuclei of the rabbit were investigated. All SCH neurons of the intact controls were similar in that they showed no morphological evidence of enhanced neurosecretory activity. In contrast, two distinct types of neurons were present within the SCH nuclei of the ovariectomized animals. The small, Type I neurons were ultrastructurally identical to the SCH neurons of the intact controls. The larger, Type II neurons, on the other hand, clearly presented structural evidence for elevated intraneuronal synthesis. To ensure that the changes which characterized the Type II neurons were due, at least in part, to the removal of ovarian steroids following ovariectomy and not to surgical stress alone, the SCH nuclei of laparotomized rabbits were also studied. Although the same two neuron types were observed, the number of Type II neurons in the laparotomized controls was significantly smaller (p smaller than 0.001) than the number in the ovariectomized group. These findings suggest that Type II neurons probably represent a functional state of the smaller, non-active neurons of the intact controls. In addition, the ultrastructural features that distinguish type II neurons are positively related to the endocrine state of the rabbit and, therefore, may represent the hypothalamic synthesis of the releasing hormones that control is gonadotropic activity.

Animals↗