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Biomedical subjects

M Santos

Publications and source records attributed to M Santos.

At least 235 records · Page 13Linked to original sources
PubMed1980

Ultrastructural study of apatites in human urinary calculi.

Using transmission and scanning electron microscopy, we have studied the ultrastructure of a number of urinary calculi, mainly composed of calcium phosphate. Three fundamental kinds of calcium phosphates were detected: nonstoichiometric carbonate apatite, nonhexagonal octacalcium phosphate, and calcium-magnesium whitlockite. The influence that the organic matter, substitutions in the phosphate lattice of CO3 and Mg, and apatitic stoichiometry have on the ultrastructure of the calcium phosphate calculi has been detailed. An originating apatitic unity named U2 is assumed to be the responsible for all the different structures of calcium apatites appearing in renal calculi. On the basis of our observations, a mechanism whereby apatites grow is postulated; magnesium functions as an inhibitor for the growing mechanism.

Apatites↗
PubMed1980

Biochemical differences between products of the Adh locus in Drosophila.

An analysis of the molecular properties of the major alcohol dehydrogenase (E.C.1.1.1.1.) allozyme variants found segregating in natural populations of D. melanogaster is presented. Our results indicate: (1) ADH-S enzyme has generally lower Michaelis-Menten constants than those of ADH-F; (2) ADH-S and ADH-F enzymes display opposite interactions for both co-factor and substrate; and (3) higher levels of ADH are associated with the Adh-fast genotype. The possible adaptive significance of these findings is discussed.

Alcohol Oxidoreductases↗
PubMed1980

Experimental colon cancer in the absence of intestinal contents in Sprague-Dawley rats.

The proximal and distal ends of the transverse colons of 16 noninbred Sprague-Dawley rats were severed and stitched to their abdominal walls. The ascending and descending colons were anastomosed end-to-end. The disarticulated colon loop was rinsed 30 times over 15 days to remove all traces of dimethylhydrazine (21 mg/kg body wt) for 27 weeks. When rats were killed 3 weeks later, 4 had invasive carcinomas and 2 had tubular adenomas in the end-to-end anastomosed (function-isolated) colons. Three rats developed invasive carcinomas in the isolated (defunctionalized) colon loops. The carcinogen probably reached the isolated colon loop through the circulation and induced (independently of bile acids) mucosal changes that led to invasive carcinoma.

Adenocarcinoma↗
PubMed1979

Composition of apatites in human urinary calculi.

Calcium-deficient carbonate apatites in urinary calculi from 17 patients have been studied. Magnesium ions in each case were detected as a component of apatite. In most of the cases, CO23- ions were included in the apatitic lattice. Using a calcination procedure, we have determined the most probable average value for the CO23- content, degree of deficiency, x, and the Mg/Ca ratio in each sample.

Apatites↗
PubMed1979

CT studies of the liver in vitro: a report on 82 cases with pathological correlation.

Eighty-two liver specimens were studied by both computed tomography (CT) and pathological examination with serial sectioning. In vitro CT studies showed low density structures within 57 normal livers to be due to portal and hepatic vessels but not to bile ducts. A liver with a minimum of 70% fatty infiltration could be diagnosed correctly on CT. Concerning the presence or absence of circumscribed liver disease, sensitivity was 80% and specificity was 84%. With respect to the total number of space occupying liver lesions (n = 364 in 18 specimens), sensitivity was 72%. The smallest metastases detectable on CT were 0.5 cm in diameter, but CT disclosed focal lesions of this small size in only 15% of the cases. In contrast to previously reported in vivo CT studies, metastases were often found to be of higher density than normal liver tissue in vitro.

Diagnostic Errors↗
PubMed1979

[Stage I and II cancer of the cervix. Report on the results of treatment in 1,015 patients (author's transl)].

The results of treatment in 1,015 stage I and II patients with cancer of the cervix are presented. The 5 year survival and recurrence rates were calculated in relation to the treatment applied. Two groups of stage Ib and IIa patients were available, one of them having been treated with radiotherapy, and the other one with radical hysterectomy and pelvic lymphadenectomy after previous intra cavitary radiumtherapy. The difference in the survival rates between the two stage Ib groups is not statistically signficant. We did not try to make a statistical comparison between the two stage IIa groups because the combined therapy group includes only patients with very early lesions. Most stage IIb patients were treated with radiotherapy. The postoperative mortality was 2.2%. There were no deaths related to treatment in the group of patients treated with radiotherapy alone. Ninety percent of the recurrences appeared within 3 years after completion of treatment.

Adenocarcinoma↗
PubMed1978

Monosodium urate in urinary calculi.

In 3,000 calculi, monosodium urate was detected in 50 cases (1.66%). Infrared frequencies of monosodium urate are reported. In thin sections it appeared as long and thin fan-shaped or feather-like arranged crystals. Six calculi had monosodium urate as the sole component but all other cases were of mixed composition, with whewellite as the main secondary substance. The relative scarcity of monosodium urate cannot be explained by its high aqueous solubility because in urine the solubility decreases with increasing sodium concentration. Monosodium urate should be suspected in radiolucent calculi with neutral or light alkaline reaction and high uric acid and sodium concentrations in the patient's urine.

Crystallography↗
PubMed1977

beta-Adrenoceptor blocking activity of halogenated thienylethanolamine derivatives.

The synthesis of a number of ring-halogenated N-isopropyl- and N-tert-butyl-2-amino-1-(2-thienyl)ethanols has been carried out in order to ascertain the influence of chloro or bromo substitution at the thiophene moiety on their blocking beta-adrenoceptor activity. It was found that chloro- and bromo-substituted compounds exhibited a similar activity. Monohalo substitution at positions C4 or C5 of the thiophene ring resulted in comparable blocking potency, whereas C3 halo-substituted compounds were practically devoid of activity. The highest activity in these series was observed with compounds dihalogenated at C4 and C5, their effect on myocardial beta-receptors being comparable to that of propranolol.

Adrenergic beta-Antagonists↗