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Biomedical subjects

A Lopez

Publications and source records attributed to A Lopez.

At least 307 records · Page 17Linked to original sources
PubMed1980

Heparin induced thrombocytopenia: a prospective study.

Thrombocytopenia occurred in 11.6% of 43 patients prospectively randomized to receive either bovine lung or porcine mucosal heparin. Four patients received bovine heparin and developed mild to moderate thrombocytopenia after eight to twelve days which resolved when therapy was stopped in one to six days. One patient received porcine heparin and developed mild thrombocytopenia after four days. The thrombocytopenia resolved in one day in spite of continued heparin therapy. Serial blood samples from the five thrombocytopenic patients were studied for their in vitro effect upon normal platelets. These samples induced a high release of serotonin from normal platelets or caused normal platelets to aggregate in the presence of additional heparin. Release or aggregation coincided with or occurred shortly after nadir platelet counts were reached and returned toward normal following cessation of heparin. Our data constitute the first prospective study of heparin induced thrombocytopenia in which serial blood samples were studied before, during and following the onset of thrombocytopenia. They strongly support the presence of a heparin dependent co-factor, presumably an antibody, as the cause for thrombocytopenia.

Animals↗
PubMed1980

Factors associated with mortality in feedlot cattle: the Bruce County Beef Cattle Project.

The design of and the analysis of data from the Bruch County Beef Cattle Project, particularity the field study, are presented and discussed. A major value of the study may lie in its ability to relate laboratory findings to events in the field. The factor most strongly related to mortality was ration, with cattle on hay based rations having a much lower mortality on average than cattle on corn based rations. In general, management activities associated with growing cattle (as opposed to fattening) over the first winter were sparing for mortality. Groups of cattle given prophylactic vaccines or drugs within two days of arrival tended to experience higher mortality (not statistically higher) than those cattle not receiving those measures, or cattle groups recieving the same prophylactics more than 48 hours after arrival. However, these results require validation in the remaining years of the study. Fibrinous pneumonia was the most frequent diagnosis in the calves on postmortem examination.

Animal Feed↗
PubMed1980

[Hepatocyte changes in experimental iron overloading. An ultrastructural and microanalytic study].

In this paper the ultrastructural changes in hepatocytes which were experimentally induced by oral and parenteral iron overloading in Sprague-Dawley rats fed on a steatogenous U.A.R. 2-13 diet are analysed. The changes in the mitochondria consisted of flocculation, vesiculation and crystolysis. The R.E.G. showed marked phenomena of dilatation degranulation and fragmentation. The lysosomes became more numerous and increased their content of ferric macromolecules. Degenerative nuclear phenomena were also seen. A microanalytic study of the cellular organelles and nucleus was done relating the cellular lesion and the intracellular distribution of the iron.

Animals↗
PubMed1978

The binding of 3H-labelled oestradiol- and progesterone-receptor complexes to hypothalamic chromatin of male and female sheep.

Chromatin isolated from hypothalamic nuclei of sexually mature entire male and female sheep was linked to cellulose in u.v. light. The saturation binding of 3H-labelled oestrogen- and progesterone-receptor complexes, prepared by (NH4)2SO4 precipitation from the 105000g supernatant of hypothalamic cytosol, was then measured in vitro in 0.15m-KCl. Saturation binding was also measured after extraction of histones and masking acidic proteins. Salt + urea was observed to be more effective than guanidine hydrochloride in unmasking receptor acceptor sites, and the binding of labelled receptor complexes to dehistonized unmasked chromatin was shown to be largely resistant to 0.4m-KCl extraction. Whereas extents of receptor-complex binding were similar to published values for comparable preparations of hen oviduct chromatin, no sex-related difference was observed. However, binding of progesterone-receptor to chromatin was greater than that of oestradiol-receptor. Binding also increased more after removal of histones and masking acidic proteins, suggesting the presence of a greater number of progesterone-receptor acceptor sites in hypothalamic chromatin than of estradiol-receptor acceptor sites. The failure to demonstrate a sex-related difference in oestradiol-receptor binding to hypothalamic chromatin in vitro is discussed.

Animals↗
PubMed1978

Comparison of the effects of beeswax: trioctanoin and trioctanoin vehicles on 3-methylcholanthrene, benzo[a]pyrene, and 7,12-dimethylbenz[a]anthracene subcutaneous carcinogenesis in three strains of mice and one hybrid.

Subcutaneous tumor induction with three dose levels of 3-methylcholanthrene (MCA), benzo[a]pyrene (BP), and 7,12-dimethylbenz[a]anthracene (DMBA) in two vehicles was studied in C3H/Anf Cum, C57BL/6 Cum, DBA/2J, and (C57BLXC3H/Anf)F1 (BC3F1/Cum) mice. Median tumor dose levels were significantly lower when the three carcinogens were suspended in trioctanoin. When beeswax: trioctanoin (B:T) was used as a vehicle, the three carcinogens differed in their abilities to be absorbed or solubilized from the vehicle by the three strains of mice and the hybrid. In C3H/Anf mice, BP in B:T failed to produce tumors. In BC3F1 mice, no tumors were produced by MCA, BP, or DMBA in B:T. In C57BL/6 mice, no tumors were produced with DMBA or MCA in B:T. In DBA/2 mice, no tumors were produced by BP or MCA in B:T. These results indicated that the interpretation of tumor induction results obtained with B:T vehicle may be related to the conditions of bioassay rather than to the carcinogenic potential of a compound.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Serum lipid changes in medical students.

Changes in serum lipids and reasons for these changes were evaluated in 108 medical students, Class of 1975. Serum cholesterol and serum triglycerides were analyzed in their freshman and senior years. A self-administered questionnaire was used to determine if the education in medical school or the knowledge of their freshman lipid vales motivated the students to change their diet and exercise habits. During this four-year period, there was a statistically significant decrease in the mean cholesterol levels (-10 mg. per 100 ml.), while the values increased slightly but not significantly for mean triglyceride (3 mg. per 100 ml.) and weight (2 lb.). Students with abnormal lipid values in their freshman year changed their diets more frequently than those with normal values. When the students were grouped by their change in diet and exercise habits, the largest decrease in lipid values was in those who changed both their diet and exercise. However, the changes in lipid values could not be totally attributed to the students' change in habits. Results suggest that detection and education may contribute to changes in certain risk factors associated with coronary heart disease in young medical students.

Body Weight↗
PubMed1976

Histologic study of elastin-like fibers in the attached gingiva.

Fifty-seven specimens of attached gingiva have been stained for elastic fibers. The number of elastin-like fibers in the papillary layer and reticular layer of the lamina propria have been scored using a scale of 0 to 3. Using similar H & E stained sections, the amount of inflammation was also scored. The presence of elastinlike fibers in the reticular layer of lamina propria of the attached gingiva has been described. Fibers have been found in the walls of blood vessels and they have been found intermingled with the dense collagenous tissue. While an attempt was made to establish a relationship between the relative number of elastin-like fibers and patient's age or degree of inflammation, lack of sufficient number of specimens at age troups precluded this.

Adolescent↗
PubMed1976

[Lymphoblastic transformation by fractions of Brucella in patients having had brucellosis and subjects vaccinated by the vaccine PI].

Two fractions of brucella, examined elsewhere for their vaccinal properties (P.I. and 4A) have been used in lymphoblastic stimulation tests with lymphocytes of subjects infected by brucellosis and subjects vaccinated with P.I. This investigation attempted to show the importance of cellular immunity in brucellosis and to deduce a valid protection test. The two fractions do not possess non-specific mitogenic activity for human lymphocytes, but they stimulate specifically the sensitized lymphocytes. Subjects formerly or recently infected with brucellosis present constantly positive tests with sometimes a very high stimulation index. Vaccinated subjects have a lower stimulation index which is, however, significant in practically each case. The P.I. fraction gives the most constant results in the two categories of subjects; 4A appears to be much less active. The divergence between the protection rates conferred by 4A to animals and the weak activity of this same fraction in stimulation tests of human lymphocytes raises, on the one hand, the problem of the relation between protection and cellular immunity and, on the other hand, the utilization of animal models for the investigation of human vaccines.

Brucella↗
PubMed1976

[Chemical fractionation of Brucella melitensis and the immunizing properties of a new fraction].

A complex phenol-insoluble fraction (fraction P.I.) extracted from Brucella melitensis presents immunizing properties already described by the authors. This fraction contains peptidoglycane whose immuno-adjuvant properties are known in numerous bacterial species. More precise fractionation was carried out to determine if the properties observed after injection of P.I. are in fact specific or on the contrary due to peptidoglycane action. By chemical and enzymatic treatments, 90% of the P.I. are eliminated, leaving a 4A fraction having the same properties as P.I. and having the advantage of providing better protection. This protection specific to genus Brucella and slow in appearing, is not due to peptidoglycane. The 4A fraction consists essentially of peptidoglycane linked covalently with a lipoprotein and proteins of weak molecular weight. All attempts at more precise fractionation have until now led to the loss of biological activity.

Animals↗
PubMed1976

The pulmonary clearance of Pasteurella hemolytica in calves infected with bovine parainfluenza-3 virus.

The purpose of this study was to determine if parainfluenza-3 virus in calves interfered with normal pulmonary bacterial clearance. Three groups (A, B and C) of four calves each were exposed to an aerosol of parainfluenza-3 virus. Three days later the four hour pulmonary clearance of Pasteurella hemolytica was determined on the first group (A), seven days later on the second (B) and 11 days later on the third (C). Group A had a mean pulmonary bacterial retention of 3.6 +/- 3.5%. Group B was 83.1 +/- 35.9% and Group C was 41.2 +/- 30.9%. The results demonstrate that parainfluenza-3 virus interfered with the pulmonary bacterial clearance of Pasteurella hemolytica particularly on day 7 and also on day 11 but not on day 3. This inhibition of pulmonary clearance caused by the virus may be a key factor in the pathogenesis of pneumonic pasteurellosis. Histological examination of the lungs did not demonstrate a correlation between pulmonary retention of bacteria and the development of pathological changes.

Animals↗