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Biomedical subjects

C Gonzalez

Publications and source records attributed to C Gonzalez.

At least 289 records · Page 16Linked to original sources
PubMed1981

Physiological and pharmacologic effects on TH activity in rabbit and cat carotid body.

The carotid bodies, along with the superior cervical ganglia and the adrenal glands, were removed from rabbits and cats and the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, was assayed by the method of Nagatsu (Anal. Biochem. 9: 122-126, 1964). The activities of the enzyme, in nmols tyrosine hydroxylated x h-1 x mg tissue-1, were: carotid body, rabbit 1.29, cat 0.84; superior cervical ganglion, rabbit 8.66, cat 4.97; adrenal gland, rabbit 0.95, cat 2.25. With respect to the carotid body, each of the following experimental procedures resulted in a long-term increase in TH activity in the rabbit but not in the cat: 1) severe hypoxia (5% O2 in N2 for 1 h, assay of TH 48 h later); 2) chronic transection of the carotid sinus nerve (assay of TH at 12-15 days); or 3) administration of reserpine (10 mg/kg at 0 and 24 h, assay of TH at 48 h). These observations are compared with our previous findings for rat carotid body and are discussed in relation to the role of catecholamines in chemoreception, and, in particular, to the reported differences in dopamine action in the carotid bodies of these different species. Our results also suggest species differences with respect to the participation of the sympathoadrenal system in response to reserpine and hypoxic stress.

Adrenal Glands↗
PubMed1981

Plasma and pituitary concentration of growth hormone in male and female rats during a 24-hour period.

The aim of this study was to investigate the pattern of growth hormone (GH) secretion during a 24-hour period in the rat, in order to determine whether differences in plasma GH between male and female animals could be demonstrated. The daily fluctuations of plasma GH were characterized by three major bursts of secretion occurring at 09.00, 16.30 and 21.00 h in both sexes. In females, the three peaks were of the same extent, while in males the night peak was greater than the other two. Female rats maintained higher GH levels than males at 09.00, 12.00 and 16.30 h, while no differences between both sexes were found at all other times. These results show that sampling time seems to be of great importance in evaluating the differences in plasma GH concentration between experimental groups in which there could be marked differences in the daily patterns of hormone secretion.

Animals↗
PubMed1981

Continuing occurrence of thyroid nodules after head and neck irradiation. Relation to plasma thyroglobulin concentration.

We re-examined 158 subjects from a group of 226 previously normal persons who had received head and neck irradiation, 113 with elevated plasma thyroglobulin levels at their first visit and 113 with normal levels. Twenty-four subjects had thyroid scintigrams that had changed in the follow-up interval of 24 to 60 (mean = 45.3) months. Twelve subjects subsequently had thyroidectomy, and five malignancies were found. In the other 12 the changes tended to be more subtle, but in nine they very likely represented thyroid nodules. We conclude that the prevalence of radiation-induced nodules is not decreasing. More changes (17 of 24) occurred in subjects who initially had elevated plasma thyroglobulin levels (p less than 0.05). However, the difference was not significant when the analysis was limited to the almost certain development of a nodule. Longer follow-up will be needed to ascertain whether a high thyroglobulin level predicts a greater risk of developing thyroid nodules.

Child, Preschool↗
PubMed1978

Halobacterium vallismortis sp. nov. An amylolytic and carbohydrate-metabolizing, extremely halophilic bacterium.

The extremely halophilic bacterium (formerly designated as strain J.F. 54) isolated from salt pools of the Death Valley, California, is a motile, Gram-negative, extremely pleomorphic organism, aerobe, and facultative anaerobe. A variety of carbohydrates are assimilated with or without acid production; soluble starch is hydrolyzed. The organism is not proteolytic; catalase, oxidase, and DNase reactions are positive; Tween 20 is slightly hydrolyzed, but Tweens 40, 60, and 80 are not. Nitrates are reduced to nitrites with gas production; nitrites are not reduced. Optimum growth temperature is 40 degrees C. Growth is inhibited by bacitracin and by novobiocin. The type strain J.F. 54 differs from described species of the genus Halobacterium and is assigned to a new species, Halobacterium vallismortis sp. nov.

Carbohydrate Metabolism↗
PubMed1976

Comparative efficacy of chloramphenicol, ampicillin, and co-trimoxazole in the treatment of typhoid fever.

Two clinical trials were conducted to compare the efficacy of 3 antimicrobial agents often recommended for the treatment of typhoid fever. Chloramphenicol was more effective than parenteral ampicillin or oral co-trimoxazole (trimethaprim/sulphamethoxazole) in reducing the duration of fever. Oral chloramphenicol was more effective than parenteral chloramphenicol probably because oral doses resulted in higher blood concentrations of the drug. However, parenteral chloramphenicol was given during the initial period of acute illness, without loss of efficacy.

Administration, Oral↗
PubMed1976

Comparative properties of bacteriophage phi6 and phi6 nucleocapsid.

Nonionic detergent treatments released a nucleocapsid from the enveloped bacteriphage phi6. The nucleocapsid sedimented at nearly the same rate as the whole phage in sucrose density gradients, but the buoyant density in Cs2S04 changed from 1.22 g/cm3 for the whole phage to 1.33 g/cm3 for the nucleocapsid. The detergent completely removed the lipid and 5 of the 10 proteins from the phage. Surface labeling of the phage and nucleocapsid with 125I revealed that protein P3 was on the outer surface of the whole phage and P8 was on the surface of the nucleocapsid. Both the phage and the nucleocapsid were stable between pH 6.0 and 9.5. Low concentrations of EDTA (10-4 M) dissociated the nucleocapsid but had no effect on the whole phage. The nucleocapsid contained all three double-stranded RNA segments, as well as RNA polymerase activity.

Bacteriophages↗