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Biomedical subjects

M Rubio

Publications and source records attributed to M Rubio.

At least 181 records · Page 10Linked to original sources
PubMed1992

Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin.

Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.

Animals↗
PubMed1991

Heterogeneous astroglial response in the rat spinal cord to long-term portacaval shunt: an immunohistochemical study.

Glial fibrillary acidic protein (GFAP) immunoreactivity has been used to study the astroglial response in the rat spinal cord to long-term portacaval shunt (PCS). The astroglial response in PCS rats is heterogeneous. In general, astrocytes show a loss of GFAP immunoreactivity, as well as shrinking and pyknosis in their nuclei; however, while GFAP reactivity was unchanged in the periependymal region, it was strongly increased in the dorsolateral region of the spinal cord (lateral spinal nucleus, dorsal root entry zone, and the most dorsal region of the dorsal horn). Three possibilities are postulated to explain how astrocytes, in the periependymal and dorsolateral regions, can support the effects of PCS: a) astrocytes related to glutamatergic pathways ought to possess a more efficient ammonia uptake and detoxification system, b) long-term PCS can activate nociceptive pathways (substancePergic fibers), and c) astrocytes located in periependymal and dorsolateral regions can be exposed to lower concentrations of ammonia because of its diffusion into the cerebro-spinal fluid close to these regions.

Ammonia↗
PubMed1991

Pharmacokinetics of ceftazidime in sheep and its penetration into tissue and peritoneal fluids.

Serum, tissue and peritoneal fluid concentrations of ceftazidime were studied in ewes after intravenous, intramuscular and subcutaneous administration at 50 mg kg-1 bodyweight. Tissue and peritoneal cages were implanted in the animals studied. After intravenous bolus administration, the mean serum concentration versus time profile was best described by a two-compartment open model. The distribution rate constant (alpha) was 3.5 +/- 1.1 h-1 and the half-life (t 1/2 alpha) 0.22 +/- 0.09 hour. The elimination rate constant (beta) was 0.43 +/- 0.04 h-1 and half-life (t 1/2 beta) 1.6 +/- 0.2 hours. The area under the curve was 275.7 +/- 84.0 micrograms.ml-1 h. The volume of distribution as steady state was 356.1 +/- 208.0 ml kg-1. The penetration ratio into tissue fluid was 62.6 +/- 15.1 per cent and into peritoneal fluid 61.1 +/- 16.5 per cent. After intramuscular injection, the elimination half-life was 1.7 +/- 0.2 hours, the area under the curve was 228.7 +/- 43.3 micrograms.ml-1 h. and the elimination rate constant was 0.42 +/- 0.05 h-1. The penetration ratio into tissue fluid was 68.5 +/- 37.3 per cent and into peritoneal fluid 73.3 +/- 34.4 per cent. After subcutaneous injection, the elimination half-life was 1.8 +/- 0.5 hours, the area under the curve was 231.8 +/- 65.6 micrograms.ml-1 h. and the elimination constant was 0.41 +/- 0.10 h-1. The penetration ratio into tissue fluid was 47.2 +/- 3.5 per cent and into peritoneal fluid 58.1 +/- 15.6 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Antiproliferative effect of interleukin-4 in B chronic lymphocytic leukemia.

Recombinant interleukin-4 (IL-4) profoundly inhibits the proliferative response of chronic lymphocytic leukemic B cells (B-CLLs) to recombinant interleukin-2 (IL-2). In the present study, we confirmed and extended these data by showing that IL-4 strongly suppresses the [3H]thymidine incorporation by B-CLLs stimulated by recombinant tumor necrosis factor alpha, recombinant interferon alpha, IL-2, and low molecular weight B cell growth factor in the absence of costimulant. Recombinant interleukin-4 inhibits spontaneous DNA synthesis suggesting that it also interferes with the autocrine proliferation of these cells. Kinetic studies indicate that IL-4 suppresses rather than shifts the peak of cytokine-induced DNA synthesis. Moreover, IL-4 blocks the progression of B-CLLs in or into G1 stage of the cell cycle as shown by the inhibition of cytokine-induced [3H]uridine incorporation. Finally, IL-4 pretreatment of B-CLLs prevents their subsequent proliferative response to the above cytokines, indicating that IL-4 confers to the B-CLLs a state of resistance to numerous stimulatory cytokines. The antiproliferative effects of IL-4 suggest that this lymphokine may have important therapeutic implications for the B-CLL patients.

Cell Cycle↗
PubMed1991

Sexual dimorphism in the distribution of glial fibrillary acidic protein in the supraoptic nucleus of the hamster.

The supraoptic nuclei (SON) of the hypothalamus of male and female hamsters were examined immunohistochemically at 1 month of age for possible sex differences in astroglial organisation. The morphometric analysis revealed the presence of more glial fibrillary acidic protein (GFAP) immunostaining in the SON of males as compared with females. GFAP-positive processes were located among the neurosecretory neurons in the males, but were quite scarce among these neurons in the female SON. These results indicate the existence of sexual dimorphism in the SON which could be mediated by sex steroids.

Animals↗
PubMed1990

Distribution and characteristics of the different astroglial cell types in the adult lizard (Lacerta lepida) spinal cord.

The astroglial cells have been studied in the lizard spinal cord by means of metallic impregnations, immunohistochemical (glial fibrillary acidic protein) and ultrastructural methods. Three astroglial cell types have been immunohistochemically identified: ependymocytes, radial astrocytes and astrocytes. Transitional forms have also been observed. Scarce immunopositive ependymocytes were located in the dorsal and ventral regions of the ependyma. The radial astrocytic somata were located around the ependymal layer and their processes reached the subpial glia limitans. Typical astrocytes were the most abundant astroglial cell type; astrocytes located in the ventral horn showed a greater development than those of the dorsal horn. In the white matter, the astrocytes were large and their processes formed part of the subpial glia limitans; on some occasions, astrocytic cell bodies also formed part of this subpial limitans. Transitional elements between astrocytes and radial astrocytes were observed in both grey and white matter. The perivascular and subpial glia limitans were continuous and showed a strong immunoreactivity. The comparative analysis of our results in the lizard spinal cord with those in other vertebrate groups leads us to conclude that reptiles could represent the key group in the phylogenetic evolution of the astroglial cells in vertebrates.

Animals↗
PubMed1989

A preliminary trial of the programmable implantable medication system for insulin delivery.

We undertook a trial to determine whether an implanted insulin-delivery system, the programmable implantable medication system (PIMS), could be used to treat patients with insulin-dependent diabetes. PIMS is a pulsatile, programmable pump with a battery life expectancy of five years. The reservoir is refilled transcutaneously every two months with a surfactant-stabilized human insulin preparation containing 400 U of insulin per milliliter. Eighteen patients received PIMS-delivered insulin for 4 to 25 months (mean, 18). The total PIMS-implantation experience comprised 28 patient-years. Good glycemic control was established and sustained during treatment (mean plasma glucose level, 7.3 mmol per liter; mean glycohemoglobin level, 8 percent [upper limit of normal, 7.5 percent]), with significantly reduced glycemic fluctuations. The total mean daily insulin dose did not change. Insulin solutions withdrawn from the pump reservoirs contained 92 percent native insulin and preserved biologic activity. There were no surgical or skin complications, severe hypoglycemic episodes, or instances of diabetic ketoacidosis. One pump was replaced because of a manufacturing defect, and four patients had catheter blockages due to omental-tissue encapsulation; two withdrew from the study and two had devices that were repaired successfully. The actuarial rate of survival of catheter function was 78 percent at 1.5 years. We conclude from this pilot study that insulin treatment with an implanted, variable-rate, programmable pump is feasible for periods up to two years.

Adult↗
PubMed1989

[Distribution of the vascular network of the adenohypophysis of the rat].

From various experiments it has been suggested that the blood flow to the different parts of the adenohypophysis is not the same. By developing the peroxidase activity of the red and white blood cells we have obtained a satisfactory image of the distribution of the intrahypophysial vessels, which indicate that the organization and distribution of these vessels varies from one portion to another in the pars distalis. On the lateral portion of the gland vascular routes are irregular, whilst in the media zone they run in a sagittal plane. Between the above-mentioned portions, on either side of the edge of the pars intermedia, a rich vascular network extending along the dorsal limit, which is fed by the long portal vessels and by numerous smaller vessels from the ventral vascular chain of the pars intermedia and neural lobe, is observed.

Animals↗
PubMed1989

Contribution to knowledge of GABAergic innervation of the intermediate lobe of the hypophysis.

Regulation of the synthesis and release of peptides by the melanotropic cells of the intermediate lobe of the murine hypophysis is mainly brought about by innervation of the lobe by dopaminergic and GABAergic fibres. The present work reports on a study of the distribution of nerve fibres inside the gland by immunocytochemical identification of the GABA contained in the axons.

Animals↗
PubMed1988

Morphological study of the rat pituitary follicle stimulating hormone cells after alternate day treatment with luteinizing hormone-releasing hormone (LHRH).

The action of the luteinizing hormone-releasing hormone (LHRH) on the hypophyseal gonadotrophins has either an activatory or inhibitory effect depending on the doses administered or on the treatment followed. Both factors can induce a different response in the two hormones. In this work, the effect after the administration of 8 doses (40 micrograms/day) of LHRH at intervals of 48 hours, on the serum levels of follicle stimulating hormone (FSH), as well as the numerical density, distribution, intensity of staining and morphometrical parameters of the cells which react against the anti-FSH serum, are assessed. It has been found that with the treatment an increase of FSH serum levels, without modification in the number of immunoreactive cells, but a clear increase in the lightly stained cells, is produced. The distribution of the reactive cells, uniform in normal animals, shows a large numerical density in the dorsal and posterior hypophyseal areas in the treated animals. No change was observed in the nuclear and cellular areas between the different groups.

Animals↗
PubMed1987

[Subacute cutaneous lupus erythematosus. Treatment with sulfone].

We present a patient with annular subacute cutaneous lupus erythematosus who was successfully treated with low doses of sulfones. A very photosensitive cutaneous eruption and scanty systemic symptoms are characteristics. Also there are ANA and anti-Ro positives but the anti-DNA antibodies negatives as immunological markers. The treatment with sulfones will be a valid treatment when safer drugs have failed.

Acute Disease↗