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Biomedical subjects

A Castro

Publications and source records attributed to A Castro.

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

Effects of age and cigarette smoking on serum concentrations of lipids and apolipoproteins in a male military population.

The effects of age and cigarette smoking on lipids and apolipoproteins were studied in men, 20-65 years old, randomly selected from a military population in the Madrid area, Spain. Subjects were classified as non-smokers, medium smokers (10-20 cigarettes/day) and heavy smokers (more than 20 cigarettes/day). Smoking prevalence was 58%. Serum apolipoprotein A-I and HDL-cholesterol (HDL-C) were not age-dependent, while total cholesterol (TC), triglycerides (TG), LDL-cholesterol (LDL-C) and the TC/HDL-C ratio increased with age. None of the variables studied was age-dependent over 30 years. The effects of smoking on TC, TG, LDL-C, HDL-C, TC/HDL-C ratio, apolipoprotein A-I, apolipoprotein B, and apo A-I/apo B ratio in the 20-29-year-old group appeared to be prominent in heavy smokers (P values less than 0.001, less than 0.05, less than 0.01, less than 0.05, less than 0.001, less than 0.05, less than 0.01 and less than 0.05, respectively) but not in medium smokers, in which only TG increased significantly (P less than 0.001). Few differences were noted between non-smokers and smokers over 30 although the TC/HDL-C ratio did increase in heavy smokers (P less than 0.05).

Adult↗
PubMed1989

The effect of acute and subchronic treatment with cicletanine on DOCA-salt hypertension in the rat.

Cicletanine, a new furopyridine derivative synthetized by the Institut Henri Beaufour (France) was found to work as an efficient antihypertensive agent in DOCA-salt rats. This compound also inhibited the development of cardiac hypertrophy characteristic of this sort of hypertension. The mechanism of antihypertensive action at nondiuretic doses of cicletanine remains to be studied.

Animals↗
PubMed1989

Normotension with decreased plasma renin activity and low serum ionic calcium levels: a prehypertensive state?

We studied the relationships between the renin-angiotensin-aldosterone system and calcium and magnesium levels in both serum and urine in 51 volunteer normotensive subjects, divided into two groups. Group 1 was made up of the 25 subjects whose levels of plasma renin activity were the lowest (1.93 +/- 0.70 ng/ml/hr). Group 2 comprised the 26 subjects with the highest plasma renin activity levels (4.80 +/- 0.84 ng/ml/hr). The following parameters were measured on all subjects: plasma renin activity and plasma and urinary aldosterone levels (by radioimmunoassay), serum ionic calcium levels (by Nova-2), total serum calcium, and serum and urinary magnesium values (by atomic absorption), serum and urinary sodium and potassium levels (by flame photometry), and creatinine clearance. In the group with low plasma renin activity (group 1), our findings included low serum ionic calcium levels (P less than .001); high coefficients of plasma aldosterone/plasma renin activity and urinary aldosterone/plasma renin activity (P less than .001); a significant correlation between the serum ionic calcium level and plasma renin activity (P less than .001); and an inverse correlation between systolic arterial tension and the serum ionic calcium level (P less than .05). These changes were more similar to change described in hypertensive patients with low plasma renin activity than to the findings in group 2 subjects. We speculate that normotensive subjects with low plasma renin activity present significant changes in the relationship between the renin-angiotensin-aldosterone system and sodium and calcium levels, and that this group is at risk for hypertension. A diet low in sodium and high in calcium could be an effective preventive measure.

Adult↗
PubMed1989

Studies on the mechanism of action of the antihypertensive agent cicletanine.

DOCA-salt rats have been previously shown to respond readily to the antihypertensive agent cicletanine (C). To study the mechanism of action of this drug, DOCA-salt rats were subchronically (14 d) treated with a 30 mg/kg (p.o.) dose of C and, once killed, their thoracic aortas challenged with a concentration (0.1 microM) of the vasocontractile agent noradrenaline (NA). Arteries from rats treated with C responded less to NA than the arteries from rats given placebo for the same time period. In another set of experiments, prior treatment with the inhibitor of prostaglandin synthesis indomethacin (2 x 2.5 mg/kg, s.c.) blunted the acute antihypertensive effect of C (30 mg/kg, p.o.) in this experimental model. These data suggest that C may work through a long-term induced blockade of the sympathetic tone that could be somehow related to a promotion of the formation of the vasodilator prostaglandin prostacyclin.

Animals↗
PubMed1979

Ectopic human chorionic gonadotropin in breast carcinoma.

Immunoreactive human chorionic gonadotropin (hCG) was found in 9 of 65 surgically removed malignant breast tumors. Concentrations ranged from 5 to greater than 500 mIU hCG/g tumor. hCG was measured by a beta-chain specific readiommunoassay. In further study of these specimens, an immunoperoxidase staining technique was used to stain for hCG in formalin-fixed sections. The hCG was shown to be localized within the cytoplasm and on the surface of the malignant cells.

Breast Neoplasms↗
PubMed1979

Automated radioimmunoassay of nicotine.

We have developed an automated nonequilibrium procedure for the radioimmunoassay of nicotine. The use of a unique iodinated nicotine derivative in this procedure gave a sensitivity of 10 micrograms/l for nicotine with a between-run precision of 7.4% and within-run precision of 6.0%. Nicotine levels of 60 to 67 micrograms/ml were found in subjects 15 min after smoking one standard cigarette. The technique herein reported is a very rapid, and sensitive radioimmunoassay for nicotine and facilitates the determination of nicotine in smoking subjects during the actual process of smoking.

Adult↗
PubMed1979

Immunoglobulin G- and M-specific enzyme-linked immunosorbent assay for detection of dengue antibodies.

An enzyme-linked immunosorbent assay for the detection of antibodies to dengue virus is described. This method correlates well with a hemagglutination inhibition technique. The enzyme-linked immunosorbent assay can also be specific for human immunoglobulin M antibodies when a mu-chain-specific antiglobulin-enzyme conjugate and fractionated serum are employed. By using this technique, dengue immunoglobulin M antibodies were demonstrated in an infant suspected of having a recent dengue infection.

Antibodies, Viral↗
PubMed1979

Enzyme-linked immunosorbent choriomammotropin assay.

We have devloped an enzyme-linked immunosorbent assay for determining choriomammotropin (human placental lactogen) in serum. Unlabeled hormone competes with choriomammotropin-beta-galactosidase conjugate for antibody bound to polystyrene tubes. The entire assay can be performed in 2.5 h with good precision. The coefficient of variation for one sample with a mean concentration of 5.6 mg/L, assayed 10 times on the same day, was 5.7%. The coefficient of variation for nine samples (3.5 to 9.0 mg/L) assayed on five different days was 7.9%. Forty-eight clinical samples were assayed (y) and compared with results obtained by radial immunodiffusion (x). The resulting regression equation was: y = 1.05x + 0.78; r = 0.91.

Enzyme-Linked Immunosorbent Assay↗
PubMed1979

Steric hindrance enzyme immunoassay (SHEIA); a novel method in enzyme immunoassay.

We have developed a new method for separation of antibody bound and unbound enzyme conjugates. The technique as applied to the assay of choriomammotropin involves the use of beta-D-galactosylamine bound to agarose to separate the unbound choriomammotropin-beta-galactosidase conjugates for antibody bound conjugates. When beta-galactosidase was conjugated with choriomammotropin using the N-hydroxy-succinamide ester of m-maleimidobenzoic acid the affinity of the enzyme conjugate to beta-D-galactosylamine attached to agarose diminished markedly following incubation with antibody. In a typical enzyme immunoassay of choriomammotropin, 5 microliter of swelled affinity gel per tube was required to precipitate unbound enzyme following one hour gentle shaking at room temperature. Choriomammotropin antibody was used at titer of 1:1,000. The standard curve for the assay was adjusted to cover a range of 0-10 mg/l with maximum sensitivity between 1-4 mg/l.

Animals↗
PubMed1979

A new radioassay for serum vitamin B12 determination using chicken serum as a binder and an anion exchange resin column separation.

We present a new method for the determination of serum vitamin B12 concentration by competitive protein binding using 57Co labeled vitamin B12, chicken serum (CS) as the binding protein, and a sephadex column separation. We placed a mixture of extracted sample, labeled B12, and CS binder above an A-25 sephadex column, and after 1 hour incubation at room temperature drained the column and washed it twice with buffer. We counted the free fraction remaining in each column. Within run C.V.'s for low and high values in the normal range were 10.6% and 6.03%. The between run C.V.'s were 7.7% and 7.5% respectively. The values obtained for 95 clinical specimens correlated well with those for a reference method.

Animals↗
PubMed1979

Plasma nicotine pharmacokinetics in dogs after intravenous administration: determination by radioimmunoassay.

Nicotine plasma levels in dogs were examined by radioimmunoassay after intravenous administration of S-nicotine at the dosage of 100 microgram/kg. After a rapid decline of nicotine level in plasma immediately following the injection, retention of the level was observed until 30 min. From that point the plasma level decreased monoexponentially. A biological half life (t 1/2, beta) of 0.61 hr we observed in dogs was similar to that in man and one half of that in rats. Total body clearance (TBC) and apparent volume of distribution (Vd, beta) in dogs were about 1/5 of that in rats. The results suggested that nicotine does not distribute in dogs as readily as in rats. Similarity in a biological half life of nicotine in dogs and humans suggested that the dog may be a better experimental model than the rate in the investigation of pharmacokinetic parameters for nicotine.

Animals↗