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Biomedical subjects

R Rodriguez

Publications and source records attributed to R Rodriguez.

At least 55 records · Page 3Linked to original sources
PubMed1989

Development of splenic natural suppressor (NS) cells in Ehrlich tumor-bearing mice.

Spleen cells from C57BL/6J mice bearing Ehrlich carcinoma growing as a solid tumor show progressive unresponsiveness to concanavalin A (Con A) and lipopolysaccharide (LPS) mitogens. This is accompanied by striking spleen enlargement with marked hematopoietic activity. Lymphoproliferative assays of normal spleen cells in co-culture with tumor-bearing spleen cells (TBSC) show that: (a) TBSC contain non-specific suppressor cells able to abrogate both Con A and LPS responses, or mixed lymphocyte reaction, of normal spleen cells and (b) suppression by TBSC is MHC-unrestricted, non-prostaglandin-mediated and greatly enhanced by Con A supernatants. Suppressor cells associated with TBSC are large, low-density cells without markers of mature B or T lymphocytes or of the mononuclear phagocyte system. Most appear to be asialo-GM1-negative, as suppression was only partially inhibited by treatment with anti-asialo-GM1 and complement. Since NK activity is lacking in TBSC, our data strongly suggest that these "null" suppressor cells are related to the natural suppressor (NS) cells found described in normal bone-marrow and neonatal spleens, or induced in adult spleens by total lymphoid irradiation, graft-vs.-host disease, or cyclophosphamide treatment.

Animals↗
PubMed1989

Inhibition of vascular endothelial cell prostacyclin synthesis by plasmin.

Vascular endothelial cells (EC) play an active role in the synthesis and assembly of components of the fibrinolytic system and the generation of the major fibrinolytic protease plasmin. However, the reciprocal effects of plasmin on EC function have not been previously examined. We have studied the actions of plasmin on the production of prostacyclin (PGI2) by cultured human umbilical vein (HUVEC) and bovine aortic (BAEC) endothelial cells. Plasmin causes little or no direct stimulation of PGI2 formation by EC. Preincubation of EC with plasmin, however, produces a time- and concentration-dependent inhibition of ionophore A23187-, thrombin-, and histamine-induced PGI2 synthesis; a smaller inhibitory effect on arachidonate- and PGH2-induced PGI2 synthesis is found. Incubation of HUVEC or BAEC with a physiologic concentration of plasminogen (180 micrograms/mL) and recombinant tissue plasminogen activator (tPA) generates tPA dose-dependent plasmin activity that exceeds that generated in the absence of EC. In the presence of plasminogen, tPA also causes a tPA dose-dependent inhibition of thrombin- and ionophore A23187-stimulated PGI2 production. PGI2 inhibitory plasmin activity is generated within the concentration range of tPA achieved in plasma during pharmacologic therapy with tPA. These findings suggest that vascular endothelial cells not only regulate activation of the fibrinolytic system but may also be targets of plasmin action on PGI2 synthesis in the modulation of hemostasis and thrombosis.

Animals↗
PubMed1989

Doppler echocardiographic evaluation of right and left ventricular diastolic function in normal neonates.

Doppler echocardiograms of the tricuspid and mitral valves were recorded along with the electrocardiogram and respiration in 22 normal full-term neonates. A computer-interfaced digitizer pad was utilized to measure the following: peak E and A velocities (cm/s); E and A areas (the components of the total velocity-time integral in the early passive period of ventricular filling [E] and the late active period of atrial emptying [A], respectively) and the 1/3 area fraction (or the proportion of filling in the first 1/3 of diastole). All of the variables of right (tricuspid) versus left (mitral) ventricular filling were significantly different on the 1st day of life. Respective values were peak E velocity (cm/s) 44.6 +/- 10.0 (tricuspid) versus 53.2 +/- 9.3 (mitral), p less than 0.01; peak E/A ratio 0.84 +/- 0.14 versus 1.15 +/- 0.17, p less than 0.0001; E/total area 0.58 +/- 0.07 versus 0.63 +/- 0.05, p less than 0.005; E/A area ratio 1.05 +/- 0.23 versus 1.63 +/- 0.40, p less than 0.0001; 1/3 area fraction 0.31 +/- 0.04 versus 0.41 +/- 0.04, p less than 0.0001; peak A velocity (cm/s) 53.0 +/- 8.4 versus 47.6 +/- 5.8, p less than 0.05 and A/total area 0.57 +/- 0.09 versus 0.41 +/- 0.09, p less than 0.001; the mean heart rate (beats/min) was not significantly different: 121 +/- 8 versus 120 +/- 7. Most of the variables remained significantly different on the 2nd day of life, but the level of significance was the same or less for all measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Cesarean Section↗
PubMed1989

Central regulation of gastric acid secretion by platelet-activating factor in anesthesized rats.

PAF has been implicated in the pathogenesis of acute gastric injury. When given peripherally, PAF induces severe gastric mucosal damage. PAF metabolizing enzymes are present in the brain but the central effects of PAF on the stomach are unknown. We have investigated in the rat the gastric secretion and gross mucosal integrity in response to intracerebroventricular (icv) PAF and compared it with that to icv TRH, a known central gastric secretagogue. Gastric acid output was markedly increased by TRH (171.6 +/- 26.3 mumol/h mean +/- SE) and by 20 micrograms/kg/h iv pentagastrin (107.6 +/- 23.6) when compared to controls receiving icv vehicle (20.2 +/- 7.5; p less than 0.01 for both). In contrast, acid output decreased after icv PAF (13.5 +/- 7.5). Furthermore, icv PAF markedly inhibited acid output stimulated by iv pentagastrin (45.1 +/- 7.03; p less than 0.05). Morphological studies showed acute gastric mucosal erosions after icv TRH and no damage was observed after icv PAF or vehicle. Thus, icv PAF reduces pentagastrin stimulated acid output and does not alter gastric mucosal integrity, whereas icv TRH stimulates acid secretion and induces gastric injury. The opposite effects of PAF and TRH suggests the existence of a gastric modulatory system at the central level.

Animals↗
PubMed1989

Analysis of synaptic events in the opossum piriform cortex with improved current source-density techniques.

1. The piriform cortex of the opossum was studied by current source-density (CSD) analysis of field potentials to determine the laminar and temporal distribution of synaptic currents evoked by lateral olfactory tract (LOT) stimulation. 2. Extracellular conductivity was measured as a function of depth at high resolution and incorporated into CSD computations. Inclusion of the conductivity term resulted in relatively subtle changes in the shapes of CSD profiles. Resolution and accuracy of CSD computations was further improved by use of a new smoothing approach and averaging of multiple potential profiles obtained at the same site. 3. The CSD depth profile resulting from LOT stimulation revealed six major synaptic events that were consistently present at anterior, middle, and posterior sites: one during the first (A1) peak of the initial surface negative dichrotic field potential component, three during the second (B1) peak, one during the surface positive field potential component (period 2), and one during the second surface negative component (period 3). In addition, CSD profiles were computed for the population spike generated by synchronous discharge of action potentials. Depths of the net inward and outward membrane currents underlying these events were correlated with the cortical lamination as determined histologically by placement of small dye marks. 4. In agreement with previous reports it is concluded that the large inward membrane current in layer Ia during the A1 wave underlies a monosynaptic EPSP evoked in distal apical dendritic segments of pyramidal cells by afferent fibers. This EPSP displays a marked paired shock facilitation. 5. Based on anatomic and physiological considerations it is concluded that the three spatially and temporally distinct inward membrane currents (sinks) that were observed in layers III, superficial Ib, and mid- to deep-Ib during the B1 wave, underlie disynaptic EPSPs resulting from direct synaptic interactions between pyramidal cells. It is postulated that the layer III sink is generated in basal dendrites largely via local axon collaterals, the superficial layer Ib sink in intermediate apical dendritic segments by association fibers originating in the anterior piriform cortex, and the deep Ib sink in proximal apical segments by association fibers originating largely in the posterior piriform cortex. 6. The latencies of the layer Ia and superficial layer Ib sinks (presumed mono- and large disynaptic EPSPs, respectively) increased from anterior to posterior. Amplitude of the superficial Ib sink relative to the Ia sink increased from anterior to posterior.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Relation between delay and survival in 596 patients with breast cancer.

To evaluate the influence of delay between first symptom and first treatment upon survival the medical records of 596 patients with breast cancer were reviewed. The following intervals were considered: less than 3 months; 3-6 months and greater than 6 months. Patients in the less than 3 months delay group had a better distribution by clinical stages and a 10-year survival rate higher than those in the longer delay groups (p = 0.034). However, within each stage no statistically significant difference in survival according to delay was observed. A Cox multivariate analysis revealed that performance status and stage of disease were independent predictors of survival, but not delay. Assuming the best prognosis for patients with clinical stages I and II and less than 3 months delay, the group with longer delay times had 15 deaths over what would have been predicted. This adverse effect was observed almost exclusively among patients over age 50 (14/15).

Adult↗
PubMed1989

Hormone-induced changes in the in vitro DNA-binding activity of the chicken progesterone receptor.

Previous analyses have indicated that steroid hormone receptors undergo an allosteric change in structure upon binding by the steroid ligand. This structural change was envisioned as an intramolecular unmasking of the protein's DNA-binding domain, thus allowing the receptor to function in gene regulation. We report an analysis of the effect of hormone on the DNA-binding activity of the chicken progesterone receptor. Using an isocratic elution of DNA affinity columns we show that unliganded receptor (aporeceptor) can bind a 23-basepair progesterone response element with high affinity and a high degree of sequence preference. Hormone causes a 1.5-fold increase in affinity for the PRE sequence and a 2-fold decrease in affinity for non-specific DNA. Kinetic analysis of the off-rate of receptor-DNA complexes is consistent with this minor effect of hormone. In addition, gel retardation analysis of receptor-progesterone response element complexes further substantiates that hormone is not required for sequence-specific DNA binding. These results indicate that hormone is not necessary for the progesterone receptor to fold into a conformation that recognizes specific gene regulatory sequences.

Animals↗
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

Clinical results with the TCu340 IUD.

A trial was carried out on the TCu340 intrauterine contraceptive device. The IUD was used by 431 women over a period of 2 years. The reasons for IUD removal were analyzed after 1 and 2 years using the life-table method. Later, the authors compared these results with the MLCu375 and the Nova-T, using the coefficient Z of Cramer. The authors concluded that the TCu340 was a high-load IUD with high effectiveness. However, there was a higher incidence of side-effects, such as pain, bleeding and expulsion in comparison to MLCu375.

Adolescent↗
PubMed1988

Tuberculosis of the rectum in a patient with acquired immune deficiency syndrome. Report of a case.

Tuberculosis of the rectum is a rare disease. A patient with a miliary pattern of pulmonary tuberculosis had a rectal lesion which proved to be tuberculosis. The patient subsequently developed several opportunistic infections characteristic of acquired immune deficiency syndrome. The clinical, endoscopic, radiologic, and histologic findings of this treatable lesion are presented.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Efficacy and safety of cilazapril, a new angiotensin-converting enzyme inhibitor.

Cilazapril (CIL), a new angiotensin-converting enzyme inhibitor, was evaluated for 16 weeks in 29 patients with mild to moderate essential hypertension (diastolic pressure 95 mm Hg to 115 mm Hg). Twenty-four patients (83%) normalized their blood pressure (BP) (diastolic pressure less than 90 mm Hg), 11 with low-dose CIL, six with high-dose CIL, one with high-dose CIL plus low-dose thiazide, and six with high-dose CIL and high-dose thiazide. Three withdrew because of side effects (fatigue, bloating, and polyuria). Statistically significant reductions in sitting and standing systolic and diastolic pressures occurred at 8 and 16 weeks on CIL. There was no change in standing or sitting heart rate, white blood cell count, creatinine clearance, urine protein levels. This is the first long-term data on this new converting enzyme inhibitor in human beings.

Aldosterone↗
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

Stage IV breast cancer: clinical course and survival of patients with osseous versus extraosseous metastases at initial diagnosis. The GOCS (Grupo Oncológico Cooperativo del Sur) experience.

The medical records of 414 patients with metastatic breast carcinoma treated between 1978 and 1986 were reviewed and 44 women were identified as having stage IV disease when the primary breast lesion was detected. Of these 44 women, 25 had metastatic disease limited to the skeleton while 19 had extraosseous lesions only. The clinical features, response to therapy, and survival were analyzed and compared for both groups. The median survival of those patients with bone-only metastases was 52 months as compared with 13 months for those with extraskeletal lesions (p = 0.0025). The response rate to first-line systemic therapy was similar for both groups (47% for bone metastases and 44% for extraosseous metastases). The median duration of response was 14 months (range, 3-55 months) for patients with bone disease and 8 months (range, 4-43 months) for those with extraskeletal lesions. We conclude that patients with metastatic breast cancer confined to the skeleton at initial diagnosis tend to follow an indolent, chronic course with prolonged survival. Therefore the increase in response rate with aggressive chemotherapy should be balanced against its higher morbidity. Further studies are needed to confirm whether the better prognosis of these patients is determined by the anatomical confinement of the disease to the skeleton or merely reflects the influence of other prognostic factors.

Bone Neoplasms↗
PubMed1987

A structural comparison of type c lysozymes based on their hydropathic profiles.

Hydropathic profiles can be considered as an approach to the three-dimensional structure of a protein and so their use for comparison of homologous proteins is proposed, as they provide information on relative structural conservativeness. A simple approach was developed for comparison of hydropathic profiles and applied to 19 lysozymes c of known primary structure. Trees were constructed in order to discover which method yielded the best estimation of the phenotypic differences between the proteins considered, by means of the goodness-of-fit criterion. Iterative methods, such as the Fitch-and-Margoliash and the unweighted-pair-group methods, gave a better fit than did a non-iterative method. When the hydropathic approach is used for comparison of lysozymes c, the enzyme obtained from chachalaca egg-white is placed closer to those from pheasant-like birds than to those of ducks; this result agrees with the morphological resemblance of the chachalaca to pheasant-like birds. Pigeon egg-white and equine milk lysozymes differ greatly in sequence from other lysozymes c and their hydropathic analysis shows important differences with respect to the other homologous enzymes.

Amino Acid Sequence↗