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Biomedical subjects

J Rodriguez

Publications and source records attributed to J Rodriguez.

At least 217 records · Page 12Linked to original sources
PubMed1990

Periventricular leukomalacia: ultrasonic and neuropathological correlations.

Ultrasound scans of a preterm neonate (27 weeks gestation) at seven weeks of age showed periventricular echo-free cavities, but these were no longer visible at 15 weeks, three weeks before the infant died. At autopsy, a linear glial scar, extending from the periventricular white-matter into the white axis of the parasagittal gyrus, was found in the area occupied by the periventricular cysts. The larger cavity was reduced to a slit-like excavation in the midst of glial tissue. Unsuspected focal infarcts in the cerebral cortex were also found. This observation demonstrates that transient echo-free cavities represent foci of cystic necrosis, which are subject to secondary collapse. In the authors' experience, the linear extension of periventricular leukomalacia (PVL) into the core of parasagittal gyri is a frequent feature of PVL, and one which cannot easily be accounted for by the usual explanations of border-zone ischaemic softening.

Brain↗
PubMed1990

Heterotopic auxiliary liver transplantation with portal flow. Gradual development of the collateral circulation.

One of the causes of auxiliary liver transplantation failure is the inter-liver competition between the host liver and the graft for the hepatotrophic factors of the portal blood. We have developed an experimental model of heterotopic partial (30%) liver isotransplant using Wistar rats so as to study this competition. Splenoportography and dissection demonstrate the existence of collateral circulation. The collaterals at 90 days post-transplant (PT) consisted of veins from the portal vein to the host liver (PR), paraesophageal veins (PE) and splenorenal veins (SR). At 60 days P.T., PR and SR veins but not PE ones appeared, and at 30 days P.T., there were only PR veins. Graft atrophy at 90 days P.T. was associated with a severe degree of bile duct proliferation. The gradual development of portal hypertension causes porto-systemic collateral circulation and the graft loses the portal hepatotrophic factors. The late development of the portal hypertension and the biliary proliferation could be caused by the hepatic arterial ischemia in this experimental model. Thus, as has been described in the orthotopic liver transplantation, the heterotopic one might require a double vascularization, both portal and arterial.

Animals↗
PubMed1989

Synaptosomal (Ca2+-Mg2+)-ATPASE activity modulation by cyclic AMP.

Dibutyryl cyclic AMP, in a concentration-dependent manner, increased synaptosomal (Ca2+-Mg2+)-ATPase activity, but in synaptic plasma membranes lacked any effect. The maximal enzyme activity in synaptosomes was increased by 38%, leaving unaltered the extrasynaptosomal Ca2+ concentration necessary to reach it. In the presence of 5 microM cyclic AMP, cyclic AMP-dependent protein kinase increased (30%) maximal (Ca2+-Mg2+)-ATPase activity in synaptic plasma membranes, but the apparent affinity for Ca2+ was not modified. This effect was partially inhibited (60%) by a cyclic AMP-dependent protein kinase inhibitor. The data suggest that synaptosomal (Ca2+-Mg2+)-ATPase activity is modulated by a cyclic AMP-dependent phosphorylation reaction.

Animals↗
PubMed1989

Effect of histamine on the development of astroglial cells in culture.

The effect of histamine on different aspects of the growth of astrocytes was studied using primary cultures derived either from forebrain or from cerebellum of the rat. The influence on general growth and differentiation was monitored in terms of the activities of ornithine decarboxylase and glutamine synthetase enzymes, whereas [3H]thymidine incorporation into DNA was used as a specific index of cell proliferation. Treatment with 500 nM histamine of cells grown for 6 days in vitro, caused a time-dependent significant increase in ornithine decarboxylase activity of astrocytes from both sources. The maximum increase was observed at 4 h after histamine treatment, at that time the elevation in ornithine decarboxylase activity being about 80% and 300% over control values in the forebrain and the cerebellar astrocytes, respectively. Under similar experimental conditions, addition of histamine (500 nM) to medium resulted in a significant increase in [3H]thymidine incorporation into DNA in both types of cultures: in comparison with control, the elevation was about 45% at 48 h in forebrain astrocytes and at 24 h in cerebellar astrocytes. On the other hand, the specific activity of glutamine synthetase in cerebellar astrocytes was markedly enhanced (about 100%) by treatment with histamine (500 nM) for 4 days, but forebrain astrocytes were little affected. Addition of histamine to the culture medium produced no significant alteration in the activity of lactate dehydrogenase and protein content of either type of astroglial cells. The present findings, which support our earlier proposal that the biochemical properties of astrocytes differ between various brain regions, provide direct evidence for the involvement of histamine in the regulation of growth and development of astrocytes.

Animals↗
PubMed1989

Salt-induced hypertension in Dahl salt-sensitive rats. Hemodynamics and renal responses.

This study was performed with Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to detect differences in cardiovascular hemodynamics and renal responses that might be involved in initiating salt-induced hypertension in DS rats. The effects of 4 weeks of 8% NaCl diet were studied in conscious, male DR and DS rats in which vascular and urinary catheters had been previously implanted. Results were compared with those obtained from control groups of DR and DS rats on 4 weeks of 1% NaCl diet. DR rats on 8% salt diet did not develop hypertension, and cardiac output and blood volume were unchanged; glomerular filtration rate, urinary flow, sodium excretion, and plasma atrial natriuretic factor (ANF) increased. DS rats on 8% salt diet developed hypertension, and cardiac output and blood volume increased; glomerular filtration rate, urinary flow, and sodium excretion did not change, despite an increase in ANF. DS and DR rats on 1% NaCl diet were subjected to ANF infusion. After ANF infusion DR rats had a decreased blood volume and an increased glomerular filtration rate, urinary flow, and sodium excretion; DS rats showed no significant changes in blood volume, glomerular filtration rate, urinary flow, or sodium excretion. ANF caused vasodilation in all regions studied in DR rats; DS rats showed vasodilation in all regions except the kidney. After acute volume expansion, although both DR and DS rats responded by an increase in cardiac output, only DS rats developed prolonged hypertension. This finding suggests an inadequate vasodilatory mechanism in DS rats. In response to acute volume expansion, renal resistance decreased in DR rats but not in DS rats. It is concluded that the primary hemodynamic disturbance in DS rats with salt-induced hypertension is an increase in cardiac output caused by blood volume expansion in the absence of any vasodilation. Comparison of the responses of DS and DR rats to high salt diets, ANF infusion, and acute volume expansion indicates that the salt-induced hypertension in DS rats is initiated by a diminished renal response to ANF.

Animals↗
PubMed1989

Induction chemotherapy in advanced head and neck cancer. Preliminary results of a randomized study.

From March 1983 to June 1986, 100 patients with locally advanced squamous cell carcinoma of the head and neck were randomized to receive either two courses of chemotherapy prior to local therapy (group A), or local therapy alone (group B). Local treatment consisted of primary radiotherapy in all patients. When a poor response was observed after 55 Gy, surgery was performed. The chemotherapy regimen was a combination of cisplatinum, bleomycin, vindesine, and mitomycin C. The response rate to induction chemotherapy (group A) was 50% for the primary tumor (CR: 10% and PR: 40%). At the end of radiotherapy, the overall tumor response rates in the two groups A and B, were 77% and 79% respectively. Complete disappearance of the primary tumor occurred more often than that of the lymph node metastases. The response rate to induction chemotherapy for lymph node metastases was 27.1% (CR: 9% and PR: 18.1%). An initial major response to chemotherapy predicted subsequent efficacy of irradiation on 90% of the cases, while a failure of chemotherapy had no predictive value in this respect. The survival rates in groups A and B were 66.5% vs. 65.1% at 1 year and 35% vs. 46.2% at 2 years. Local disease-free and disease-free intervals were similar in both groups. A Cox's multi-step regression analysis revealed two significant independant prognostic factors: size of primary tumor and nodal status. After adjustment for these factors, the chemotherapy did not seem to improve the effectiveness of the local treatment in terms of loco-regional control and survival.

Adult↗
PubMed1989

Anterior cervical debridement and strut-grafting for osteomyelitis of the cervical spine.

A retrospective review of the surgical experience in treating 18 patients with osteomyelitis of the cervical spine is reported. The patients ranged in age from 20 to 60 years and all complained of neck pain upon admission. Ten patients had a prior history of intravenous drug abuse, three had previously suffered penetrating injuries of the neck, and one had an extraspinal site of osteomyelitis. Bacteria were isolated in 13 cases and tuberculosis in three. Neurological abnormalities were present in over one-half of the patients, consisting of myelopathy (nine cases) or radiculopathy (four cases). Plain cervical spine films and polytomography demonstrated vertebral and end-plate destruction, spinal instability, and increased paravertebral soft-tissue shadow in all cases. Computerized tomography and, more recently, magnetic resonance imaging have proven helpful in detecting bone involvement and the presence of epidural extension associated with cervical osteomyelitis. The risk of vertebral body collapse, kyphosis, and myelopathy in the osteomyelitic cervical spine has standardized the management of this problem in this institution to consist of skeletal traction, needle aspiration or blood culture for organism identification, anterior cervical debridement, autogenous iliac graft fusion, and intravenous administration of antibiotics. Spinal stability and neurological improvement were achieved in all 18 patients.

Adult↗
PubMed1989

Allergy to cow's milk with onset in adult life.

We report a 29-year-old patient with a history of asthma that is sometimes accompanied by urticaria, which is related to the ingestion of milk products. Once these were excluded from his diet no symptoms were observed. Skin tests, specific IgE, histamine release, and oral food challenges were positive to cow's milk and its fractions.

Adult↗
PubMed1989

[Development of pharyngo-laryngeal surgery after radiotherapy].

Myo-cutaneous pedicled flap (MCF) had transformed technics and indications for salvage procedures after high doses of radiotherapy in laryngeal and hypopharyngeal carcinomas. Wide field total laryngectomies extended to oropharynx, skin, circular pharyngectomies extended to cervical oesophagus are possible with 3 times less carotid blow-up and rare fistulas. Radical neck dissection is currently performed in the same procedure without major healing problems. The feeding tube is often removed within a month. Systematic use of MCF in patients irradiated over 70 Gy may reduce the post-operative mortality and yield better survival rates, which at present 2 years after salvage surgery, are 36% in hypopharyngeal carcinomas (38/106) and 50% in laryngeal cancers (106/210).

Combined Modality Therapy↗
PubMed1988

Histamine stimulated synaptosomal Ca2+ uptake through activation of calcium channels.

Histamine stimulated Ca2+ uptake in synaptosomes was completely inhibited by the slow Ca2+ channel antagonists verapamil, cinnarizine and flunarizine, and slightly inhibited by nifedipine and diltiazem. Ca2+ uptake in synaptosomes depolarized or predepolarized with varying K+ concentrations was increased by histamine, in both conditions, until 30mM K+. At higher K+ concentrations histamine was not able to alter K+ effects in either conditions. 30mM K+ stimulated uptake of Ca2+ in the absence or presence of histamine was not inhibited by verapamil and diltiazem. However nifedipine slightly inhibited K+ and K+ +histamine effects. 3-Isobutyl-1-methyl-xanthine and dibutyryl cyclicAMP potentiated (10%) the uptake of Ca2+ in synaptosomes induced by histamine. Dibutyryl cyclicAMP alone however decreased the basal Ca2+ uptake in a concentration-dependent manner. Verapamil, but not diltiazem, antagonized the effects elicited by 3-isobutyl-1-methyl-xanthine and dibutyryl cyclicAMP in the presence of histamine. The data suggest that the increase in synaptosomal Ca2+ uptake induced by histamine is mediated by the activation of the voltage sensitive calcium channels, and possibly a cyclicAMP-dependent protein kinase phosphorylation can modulate the opening of Ca2+ channels.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Histamine H2-receptor mediated activation of neonatal rat brain ornithine decarboxylase in vivo.

The effect of histamine (HA) administered via intracerebroventricular injection on ornithine decarboxylase (ODC) activity was studied in neonatal rat brain. The HA effect was dose and time dependent. Maximal increase in ODC activity was achieved 2 hr after administration of 10 micrograms HA (38% over control levels). Impromidine (HA H2-agonist) mimicked the effect of HA on ODC and ranitidine (HA H2-antagonist) inhibited the response to HA. Neither 2-thiazolylethylamine (HA H1-agonist) nor mepyramine (HA H1-antagonist) modified control ODC activity. The HA-releasers, compound 48/80 and polymixin B sulfate, elicited an increase in brain ODC activity of 35% and 32%, respectively, over the control value.

Animals↗
PubMed1988

Properties and ontogenic development of membrane-bound histidine decarboxylase from rat brain.

Histidine decarboxylase (HD) activity was determined in high-speed fractions (100,000 g for 60 min) obtained from whole rat brain homogenates. Twenty-eight percent of the HD activity was associated with membranes, and the remaining was soluble. Several properties of the soluble and membrane-bound HD were compared. No significant differences in the values of Km for histidine and pyridoxal 5'-phosphate were observed. The solubilization of membrane-bound HD with Triton X-100 resulted in an increase of 60% over the nonsolubilized activity with no changes in the Km for substrate and cofactor. The proportion of free pyridoxal 5'-phosphate-independent activity was identical in both fractions. The soluble and membrane-bound forms of the enzyme differ slightly in their pH-activity profiles, although both enzymes showed an optimum pH near 6.5. The HD activities present in soluble and membrane fractions were determined at different postnatal ages. The soluble activity increased until day 90, whereas the membrane-bound activity became stabilized from day 20.

Aging↗
PubMed1988

Alcohol and tobacco consumption in cancer of the mouth, pharynx, and larynx: a study of 316 female patients.

Three hundred sixteen female patients with cancer of the larynx, pharynx, and mouth were examined and the following cancer sites were compared with respect to alcohol and tobacco consumption: oropharynx, hypopharynx, larynx, epilarynx, lip, and mouth. The mean daily tobacco consumption of smokers and ex-smokers was not significantly different between cancer locations; however, significant differences between cancer sites were observed with regard to the proportion of nonsmokers. The percentage of nonsmokers was the highest for cancer of the lips and the lowest for cancer of the epilarynx. Cancer locations differed significantly depending on daily alcohol consumption. Consumption was the lowest for patients with cancer of the lips. The percentage of nondrinkers was high for cancers of the lips and larynx and low for cancer of the epilarynx. Examination of the nonsmoking/nondrinking females (27.2%) did not reveal any features specific to this group, except that the patients were older.

Alcohol Drinking↗
PubMed1988

[Endoscopic percutaneous gastrostomy. A non-surgical method of enteral alimentation in ORL patients unable to feed orally].

Since surgical gastrostomy is not a risk-free operation in debilitated patients, a method of endoscopic percutaneous gastrostomy (EPG) is proposed. A thread is passed percutaneously into the gastric cavity and brought to the exterior through the mouth during fibroscopy. This thread allows removal of a gastrostomy tube by simple traction. Used in 18 patients with ENT cancer the EPG was simple to perform, postoperative complications being minor in 3 cases and serious in one patient. In the absence of any obstacle in the pharyngeal channel preventing the passage of a fibroscope, EPG is a simple procedure and is therefore an alternative to surgical gastrostomy.

Adult↗