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Biomedical subjects

R Garcia

Publications and source records attributed to R Garcia.

At least 487 records · Page 27Linked to original sources
PubMed1980

Effects of intracerebroventricular administration of tonin on water intake and blood pressure in the rat.

Intracerebroventricular administration of tonin, an enzyme which releases angiotensin II directly from various substrates, stimulated water intake and increased blood pressure in the rat. These responses were abolished by the simultaneous administration of an angiotensin II antagonist and were unaffected by the nonapeptide inhibitor of angiotensin I-converting enzyme. These findings suggest that tonin may participate in the physiological regulation of water balance and blood pressure through local and direct generation of angiotensin II in the central nervous system.

Angiotensin II↗
PubMed1980

Effects of tonin on vascular smooth muscle of the hypertensive rat and normal rabbit.

1. The response of arterial smooth muscle to noradrenaline was studied in one-clip hypertensive rats with or without the contralateral/kidney and in normotensive rabbits. 2. Strips of aorta from one-kidney, one-clip hypertensive animals were less responsive to noradrenaline than normotensive control rats. The contractile response of strips from two-kidney, one-clip hypertensive animals was not different from the control group. These results suggest that the mechanisms responsible for the lesser reactivity in the one-kidney hypertensive group are not a consequence of elevated blood pressure itself, but may be related to the intrinsic contractility of aortic smooth muscle. 3. Tonin potentiated the contraction induced by noradrenaline in aortic strips from hypertensive and normotensive rats. However, this effect was more important in the one-kidney, one-clip hypertensive animals. In the aortic and mesenteric strips from normal rabbits, tonin produced not only potentiation to noradrenaline but direct contraction. 4. The potentiation to noradrenaline and the direct effect of tonin were not affected by a variety of antagonists but were blocked by a calcium ion antagonist, verapamil, suggesting that tonin may act directly on vascular smooth muscle through mechanisms which might be mediated by calcium ions.

Animals↗
PubMed1980

The effects of intracerebroventricular administration of tonin on water drinking and blood pressure in rats.

Intraventricular administration of tonin, an enzyme which forms angiotensin II directly from a natural protein substrate (angiotensinogen), stimulated water drinking and increased systemic blood pressure in rats. These responses were abolished by the simultaneous administration of an angiotensin II analogue, but unaffected by an angiotensin I- converting enzyme inhibitor. We confirmed, in vitro, that angiotensin II was generated when the brain homogenate was incubated with tonin in the presence of DFP and EDTA. These results indicate that the central effects of tonin on water drinking and systemic blood pressure are mediated via the direct formation of angiotensin II in the brain, and suggest the possibility that the tonin-angiotensin II system in the central nervous system might be important in controlling water balance and blood pressure.

Animals↗
PubMed1980

Coyotes and canine heartworm in California.

Adult Dirofilaria immitis were found in the hearts of 43 of 115 coyotes (Canis latrans) trapped within a 50 km radius of the El Dorado County seat. Of mature coyotes, 45% were positive, with worm numbers averaging 9.0 in females and 16.2 in males. D. immitis microfilariae occurred in the peripheral blood and in lung smears. Microfilariae of Dipetalonema reconditum were present in 14 of the coyotes examined (12%). Several coyotes showed enlarged hearts with gross pathological changes.

Animals↗
PubMed1980

Alphaviruses in Peninsular Malaysia: II. Serological evidence of human infection.

A serum survey of several characteristic groups of humans in urban, rural, and forested areas of Peninsular Malaysia for evidence of infection with three alphaviruses (Sindbis, getah, and chikungunya) was made on 4384 specimens collected between 1965 and 1969. Analysis of the serological results indicated that 1) persons residing in predominantly rural and forested areas have higher frequencies of specific alphavirus antibody of all three viruses than persons residing in urban areas, 2) human infection with chikungunya virus appears to be at a low level of activity but is widespread, although more common and recent in the northern part of the country, and 3) Sindbis and getah viruses probably do not represent a threat to the public health, but chikungunya virus remains a potential menance and may be responsible for future epidemics transmitted by A. aegypti and A. albopictus mosquitoes.

Adolescent↗
PubMed1979

Differential expression of gizzard actin genes during chick embryogenesis.

The iso forms of gizzard actin present during chicken embryogenesis were analyzed by two-dimensional electrophoresis. During chick embryogenesis there are conspicuous changes in the content of the iso forms of actin. Gizzards from 8-day-old embryos contain almost exclusively beta-actin. After 8 days of embryonic age, there is a continuous increase in the amount of gamma-actin and an apparent decrease in the amount of beta-actin. These changes in the content of beta- and gamma-actin in gizzard tissue are paralleled by changes in the content of the corresponding mRNAs, as detected by the ability of the RNAs to direct the synthesis of these proteins in micrococcal nuclease-digested reticulocyte lysates. The correlation of the in vivo and in vitro experiments indicates that during chick embryogenesis there is a differential expression of the genes coding for the iso forms of gizzard actin and that this expression is controlled at the transcriptional level.

Actins↗
PubMed1979

Endometrial cancer and estrogen use. Report of a large case-control study.

Our case-control study of the relation between estrogen use and endometrial cancer involved 451 cases and 888 controls. The overall risk of endometrial carcinoma was sixfold for estrogen users as compared with nonusers; long-term users (greater than five years) had a 15-fold risk. Excess risk was present for both diethylstilberstrol and conjugated estrogens. The risk associated with cyclic use was as great as that for continuous use. Increased risk was associated with estrogen use for all histologic grades of the tumor. The risk of advanced-stage carcinoma was fourfold for estrogen users, but rhe confidence interval was wide, and this question requires further study. Finally, this investigation contradicts the speculation that the association between this cancer and estrogen use can be explained by swifter diagnosis for estrogen users, misclassification of estrogen-related hyperplasia or treatment of early symptoms of the tumor with estrogen.

Clinical Trials as Topic↗
PubMed1979

Acute poststreptococcal glomerulonephritis in Maracaibo. II: Studies on the incidence, nature, and significance of circulating anti-immunoglobulins.

Antiglobulins were measured in the sera of 82 patients with acute poststreptococcal glomerulonephritis and correlated with C1q binding activity, serum levels of immunoglobulins and C3, site of infection, antibody titres to streptococcal enzymes, and the duration of the nephritis and interval from infection. Raised serum antiglobulins were found in 89.2% of the patients. In addition, raised titres were detected at any time during the course of the disease and very early after streptococcal infection. The finding of antiglobulins soon after the infection suggests the possibility that they appear as a primary event in the disease.

Acute Disease↗
PubMed1979

In vitro production of IgE and IgG by sensitized human peripheral lymphocytes.

Antigenic stimulation of peripheral lymphocytes was made in two different groups of atopic patients, testing their capabilities to produce IgE and IgG in vitro. For this purpose, Marbrook's technique was used in the cultures. The immunoglobulins produced were measured in the supernatants by a sensitive double-antibody method. Results demonstrate that it is possible to produce enough IgE and IgG to be detected. Some important parameters had to be considered: appropriate selection of the patients and the antigens used in the antigenic stimulation, as well as the number of cells and the duration of the culture.

Allergens↗
PubMed1978

Effect of antitonin on blood pressure in the one-kidney hypertensive rat.

1. The tonin concentration of saliva and submaxillary glands was studied in one-clip hypertensive rats with or without the contralateral kidney. 2. Salivary tonin concentration was elevated in one-kidney hypertensive rats, but not in one-kidney normotensive or two-kidney, one-clip hypertensive rats. In contrast, an elevated submaxillary gland tonin concentration was found only in uninephrectomized animals, whether normotensive or hypertensive. 3. A single intravenous administration of rabbit tonin antiserum into one-kidney hypertensive rats restored blood pressure to normal in seven out of ten animals. There was little change in blood pressure in two-kidney, one-clip hypertensive, uninephrectomized or sham-operated rats. 4. These findings suggest a connection between the physiology of the kidney and of the submaxillary gland in the rat, and indicate that tonin may play a significant role in maintaining high blood pressure in one-kidney hypertensive aniamls.

Animals↗
PubMed1978

A direct radioimmunoassay for tonin.

A sensitive radioimmunoassay for the measurement of tonin is described. It is based on the use of antibodies produced in rabbits against highly purified tonin obtained from rat submaxillary gland. A radioiodinated enzyme with high specific activity was obtained by the chloramine-T method. Optimal conditions for radioimmunoprecipitation were established and the double-antibody method was used to separate bound and free tonin. The radioimmunoassay may be used to measure tonin in amounts as low as 150 pg. This radioimmunoassay was applied to the measurement of tonin in rat saliva and in homogenates of submaxillary glands. Excellent correlation was found between tonin activity measured fluorometrically and tonin concentration obtained by the radioimmunoassay.

Antibodies↗
PubMed1978

Quantitation of IgE on the basophil surface in atopic patient.

A radioimmunoassay was employed in order to quantitate IgE on the basophil surface in 6 normal and 10 pollen sensitive subjects. A basophil-rich fraction obtained from whole blood in a Ficoll gradient was incubated with specific anti-IgE; the inhibition produced by surface IgE was standard inhibition curve. Atopic patients had on the average about 10-30 times as many IgE molecules per basophil as control subjects. Total and specific IgE as well as degranulation by Lollium perenne crude extract were also studied in both populations and their results compared with those of basophil IgE quantitation.

Basophils↗