Showing papers by "National University of Cuyo published in 1991"
TL;DR: The results suggest that exchange of material with endosomes is an important step in the process of phagosome maturation, and the mechanisms mediating phagosomes-endosome fusion are similar to those described for endosome-endOSome fusion.
142 citations
TL;DR: Although estrogen receptor expression was moderate to high in many samples, the expression of the two biochemical markers of estrogen action at postreceptor levels was low or absent in most of the liver tissues examined, suggesting that in the liver the interaction of estrogen–estrogen receptor–DNA has characteristics inherent to this tissue.
30 citations
TL;DR: The mechanism of formation of spherules and microvesicles seemed to be formed by a different mechanism, and it is postulate that this represents an apocrine secretion process.
Abstract: Epididymides of captive normal adult cats were studied by light and transmission electron microscopy. Release of apical portions of principal cells occured by a process of pinching-off. The membrane-bound bodies (spherules) formed were then found in the epididymal lumen. We postulate that this represents an apocrine secretion process. Such phenomenon were present in all segments of the epididymis, whether caput, corpus, or cauda. Rows of microvesicles similar to those described in other species were also observed between microvilli. The mechanism of formation of spherules and microvesicles seemed to be formed by a different mechanism.
30 citations
TL;DR: Results suggest that in the epididymis there is a special transport system for hydrolases, which could be involved in the secretion of enzymes destined for spermatozoa, which would require receptors that recognize sugar ligands other than mannose-6-phosphate.
Abstract: beta-Galactosidase, known to be secreted by epithelial cells lining the rat epididymal duct, binds to the surface of spermatozoa from the caudal region with high affinity and in a saturable form. The binding was not inhibited by mannose-6-phosphate, but was inhibited by fructose phosphate derivatives, a peculiarity previously demonstrated for the membranes of epididymal tissue. Fructose phosphate derivatives released 55% of beta-galactosidase activity from the spermatozoa. These results suggest that in the epididymis there is a special transport system for hydrolases, which could be involved in the secretion of enzymes destined for spermatozoa. This transport would require receptors that recognize sugar ligands other than mannose-6-phosphate. These receptors were present in the epididymal tissue and on the sperm surface.
24 citations
TL;DR: In the rat epididymis the presence of membrane‐bounded vesicles in the stereociliar areas of the epithelial cells was studied to explore the intimate contact between principal cell stereocilia and luminal spermatozoa.
Abstract: We studied in the rat epididymis the presence of membrane-bounded vesicles in the stereociliar areas of the epithelial cells. The intimate contact between principal cell stereocilia and luminal spermatozoa was also explored. The epididymidis of adult male albino rats were fixed with Mollenhauer's fixative via the thoracic aorta; they were removed and the caput and the cauda were separated and fixed for 4 additional hours at 4 degrees C. After fixation, the samples were processed with routine techniques for transmission and scanning electron microscopy. The study showed membrane-bounded vesicles in the lumen of the caput and cauda epididymidis. They are present between stereocilia, in the most peripheral regions of the epididymal lumen, and in a stereocilia-free zone in the apical plasma membrane of the principal cells. The smaller vesicles are located near the apical surface of the latter, and the larger ones are located near the tips of the stereocilia. Their contents are electron lucent in some images and electron dense in others. In several thin sections some of the vesicles are observed to have a stalk. This suggests that the possible mode of production may be an exocytotic process. Some membrane-bounded vesicles were found to be in contact with the head or the tail of maturating spermatozoa. Moreover, an intimate contact was found to exist in the epididymidis between the plasma membranes of the spermatozoa and the stereocilia. These observations seem to suggest two possible mechanisms for sperm-epididymal cell relations: 1) release of a secretion product via the membrane-bounded vesicles and 2) direct contact between stereocilia and spermatozoa.
24 citations
TL;DR: In this article, the authors examined the seminiferous tubules of pregnant rats with TEM after fixation plus intercellular tracers, and with freeze-fracture techniques, showing that the orientation of inter-Sertoli junctions has changed to parallel, both to each other and to the basal lamina.
Abstract: Pregnant rats (day 13) received 10 mg/kg of Busulfan i.p. The seminiferous tubules of their offspring from post-natal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze-fracture techniques. During this period, the inter-Sertoli tight junctions of controls increase both in number and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes surrounded by tracer. The inter-Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene-pachytene stages. The tracer is stopped at the inter-Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes. Freeze-fracture shows that the orientation of inter-Sertoli junctions has changed to parallel, both to each other and to the basal lamina. In the Busulfan-treated rats, the tubules continue having, up to post-natal day 30, only Sertoli cells and scanty spermatogonia. In these, lanthanum penetration goes as far as the apical Sertoli cell region; the inter-Sertoli junctions still show tortuous strands, and most are oriented perpendicular to the basal lamina. This indicates that formation of the first competent inter-Sertoli junctions is temporo-spatially simultaneous with the appearance of zygotene-pachytene spermatocytes.
23 citations
TL;DR: The total cross section of Plexiglass has been measured for energies between 10 −3 and 10 3 eV by the transmission method with pulsed-neutron time-of-flight techniques as discussed by the authors.
21 citations
TL;DR: Two sets of behaviors relevant for the construction of shelters, nest building and digging, were studied in three con-generic species of South American cricetid rodents and significant differences were observed, but not between sexes within the same species.
15 citations
TL;DR: In this experimental model, allopurinol blocked or ameliorated significantly cellular injury, as shown by a decrease of amylase levels in blood, and of histopathological changes, depending on dose and time of administration.
Abstract: The effect of allopurinol, a xanthine oxidase inhibitor, on canine experimental ischemic pancreatitis was studied. The animals were divided into nine groups: 1. Group 1. Control with pancreatic ischemia; 2. Group 2. Received allopurinol once, previous to ischemia; 3. Group 3. Received allopurinol once, immediately after ischemia; 4. Group 4. Received allopurinol immediately after ischemia and then daily; and 5. Groups 5, 6, and 7 were controls for the operation, allopurinol, and its vehicle, respectively; 6. Group 8 (pancreatic ischemia) and Group 9 (that received allopurinol after ischemia and daily) were also studied histologically. Serum amylase was determined in all animals. In Groups 1 and 5, following the ischemic period, hyperamylasemia developed and a peak was reached 24 h after ischemia. In Group 2, a significant decrease of amylase levels was found, compared to matched controls immediately after ischemia and then rose, reaching on the fifth day a peak that was less than the controls at 24 h. In Group 3, the serum amylase level increased immediately to values similar to controls; later, there was a drop to levels lower than those found in controls, followed by a peak on the fifth day. In Group 4, there was no significant elevation in the amylase values. Groups 6 and 7 showed no changes of amylasemia. In this experimental model, allopurinol blocked or ameliorated significantly cellular injury, as shown by a decrease of amylase levels in blood, and of histopathological changes, depending on dose and time of administration. These results offer the possibility of a prophylactic therapy for chronic relapsing and idiopathic pancreatitis.
12 citations
TL;DR: In this article, the Laplace-Fourier-transformed probability distribution (continuous time) and generating function (discrete time) were derived for multistate random walks.
Abstract: A method is presented which allows one to obtain explicit analytical expressions (both exact and asymptotic) for many of the physically interesting quantities related to a multistate random walk (MRW). The exact results include the Laplace-Fourier-transformed probability distribution (continuous time) and generating function (discrete time), and closed evolution equations for the propagators related to each “internal” state of the walker. Analytical expressions for the scattering dynamical structure function and the frequency-dependent diffusion coefficient are given as illustrations. Asymptotic approximations to the single-state propagators are derived, allowing a detailed analysis of the longtime behavior and the calculation of asymptotic properties by single-state random walk standard methods. As an example, analytical expressions for the drift and diffusion coefficients are given.
5 citations
TL;DR: The concept that histamine is involved in the POA-AHA to control the pituitary LH release is supported and the role of plasma estrogen to facilitate the expression of HA receptors is emphasized.
Abstract: The influence of histaminergic sites in the preoptic-anterior hypothalamic area (POA-AHA) on the basal release of luteinizing hormone (LH) under a continuous regimen of estradiol, progesterone, or both was studied in ovariectomized rats. Different groups of animals were subjected to the following experimental schedule: at day 1, rats received a s.c. silastic implant filled with oil, estradiol, progesterone, or estradiol plus progesterone. Seven days later (day 7), animals were implanted into the POA-AHA with microinjection cannulae. At day 8 and 9, the different groups of rats were microinjected with 1 Μl of saline solution containing 35 nMol of pyrilamine or metiamide, or 20 nMol of alpha-fluoro-methyl-histidine. At day 10, blood samples were taken through a permanent jugular cannulae implanted in situ the day before. LH concentrations were determined in plasma by RIA. Results showed that the increase of LH plasma levels induced by the ovariectomy was inhibited by the estrogen implant, as expected. Treatment of metiamide or alpha-fluoro-methyl-histidine did not affect the pattern of LH secretion. Nevertheless, treatment of metiamide induced a transient increase in the gonadotropin concentrations that extended for two hours (16:00 and 17:00 H). No change in LH plasma levels was observed in rats bearing the progesterone implant. Treatments (pyrilamine, metiamide, or alpha-fluoro-methyl-histidine into the POA-AHA) had no effect. The transient increase in the hormone levels observed in rats treated with pyrilamine in the estrogen-implanted rats was absent in rats bearing the estrogen-progesterone implant. Present data support the concept that histamine is involved in the POA-AHA to control the pituitary LH release and emphasize the role of plasma estrogen to facilitate the expression of HA receptors.
01 Dec 1991
TL;DR: There are antigenic factors in the vector gut that are incorporated by the parasite and are recognized by the immunitary system of the human patient with production of specific antibodies according to immunocytochemistry with serum of chagasic patients as first antibody and protein "A"-gold as marker.
Abstract: Serum of chagasic patients with a high title of specific antibodies against T. cruzi antigens, binds epitopes in the midgut and hindgut of the insect vector Triatoma infestans free of parasites. These antigens were recognized at ultrastructural level by immunocytochemistry with serum of chagasic patients as first antibody and protein "A"-gold as marker. Controls with normal human serum were negative. The positive reaction occurs principally in the apical epithelial portion (microvilli and peritrophic membrane) of the midgut and in the cuticular layer and adjacent cytoplasm of the hindgut. In vectors infected with trypanosomes, the antigen-antibody reaction occurs similarly in the epithelium and also in the trypanosomes present in the lumen. These results suggest that there are antigenic factors in the vector gut that are incorporated by the parasite and are recognized by the immunitary system of the human patient with production of specific antibodies.
TL;DR: In this paper, a synthetic scattering function was used to evaluate thermal neutron cross sections and diffusion parameters for diphenyl and Dowtherm-A, over a range of temperatures of practical interest.
TL;DR: The results indicate that diazepam and beta-carboline agonists prevent the LH surge evoked by estrogen and suggest, in addition, that the actions on LH release and their sedative effects are not directly related.
Abstract: The effects of diazepam (DZ) and the β-carbolines ZK-91296 and ZK-93423 on luteinizing hormone (LH) release evoked by β-estradiol were studied in estradiol-primed ovariectomized rats. Acute treatment with 2.5, 5 and 10 mg/kg DZ and ZK-91296 significantly blunted the LH response. ZK-93423 (1, 5 and 10 mg/kg) produced a similar effect. The inverse agonist DMCM (2 mg/kg) was unable to modify plasma LH levels in estrogen-primed, ovariectomized rats. Sedative effects were observed with doses of DZ (1 mg/kg) ineffective to blunt the LH response. In contrast, ZK-91296 (5 mg/kg) produced inhibition of LH surges in nonsedative doses. These results indicate that diazepam and β-carboline agonists prevent the LH surge evoked by estrogen. They suggest, in addition, that the actions on LH release and their sedative effects are not directly related.
01 Jun 1991
TL;DR: It is postulated that temperature mainly affects the parasite resistance to intracellular digestion and the phagocytic and degradative properties of the macrophages were obtained at those temperatures.
Abstract: The interaction of macrophages and T. cruzi has been studied in vitro culture under three different temperatures. After 24 hours incubation at 29 degree C a large number of recognizable parasites inside macrophages is observed with evidences of cell divisions. At video microscopy they show a slow motion and a predominance of epimastigotes and some round shapes (amastigotes). This was corroborated at the light and electron microscopes. No evidence of lysis in the phagosome vacuoles was observed. At 40 degrees C, macrophages show a large number of residual bodies and phagocytic vacuoles with digested parasites. At 37 degrees C, an intermediate stage with normal and digested parasites inside macrophages is observed. No significant evidences of affected phagocytic and degradative properties of the macrophages were obtained at those temperatures. It is postulated that temperature mainly affects the parasite resistance to intracellular digestion.
Journal Article•
TL;DR: The present case allows us to postulate that the skeletal muscle injury was secondary to direct toxicity and/or the compromise of muscle blood perfusion by the contrast medium in a susceptible muscle due to previous renal failure.
Abstract: A case of rhabdomyolysis associated with an iodinated contrast medium (sodium diatrizoate) in a patient with chronic renal failure is presented for the purpose of discussing this association. Clinical manifestations were: diffuse myalgias, proximal muscular weakness and an acute reversible deterioration of the renal function. Muscle biopsy showed the typical pattern found in rhabdomyolysis, that is, cellular necrosis with no inflammation signs and myolytic areas. The temporal association between the rhabdomyolysis and the use of the contrast medium suggests a causal relationship. The present case allows us to postulate that the skeletal muscle injury was secondary to direct toxicity and/or the compromise of muscle blood perfusion by the contrast medium in a susceptible muscle due to previous renal failure. It is suggested that this group of substances should be incorporated to the list of agents capable of causing non traumatic rhabdomyolysis.
Journal Article•
TL;DR: It is established that the variations of the neurotransmitter concentrations of the antrum mucosa are more associated with the duodenum than with the gastric fundus, and the statistical analysis showed a significant correlation of DA concentration with lymphoplasmocytic infiltrated in Duodenum.
Abstract: We have studied the concentrations (pg/mg) of Neurotransmitters 5-hydroxytryptamine (5HT), Noradrenaline (NA) and Dopamine (DA) at mucosa normal and with different degrees of chronic inflammation mucosa of fundus (F), antrum (A) and duodenum (D) in 21 patients. We correlated the concentration of the neurotransmitters with each other, all of them in each region and with clinics, indirect of motility and histologic parameters. The average for 5HT in F: 940.2 +/- 457.4; in A: 787.5 +/- 407.0; in D: 601.6 +/- 272.0; for NA in F: 217.5 +/- 138.7; in A: 228.4 +/- 126.5; in D: 245.7 +/- 118.6 for DA in F: 50.7 +/- 32.2; in A: 46.3 +/- 31.5; in D: 53.0 +/- 45.6. The statistical analysis showed a significant correlation of DA concentration with lymphoplasmocytic infiltrated in Duodenum (r = 0,94). not any other parameter had significative relation with the neurotransmitters variations. We established that the variations of the neurotransmitter concentrations of the antrum mucosa are more associated with the duodenum than with the gastric fundus.