Biomedical subjects

F A Lopez

Publications and source records attributed to F A Lopez.

16 recordsLinked to original sources

PubMed1994

Preliminary study of treatment of sulphuric pickling water waste from steelmaking by bio-oxidation with Thiobacillus ferrooxidans.

This report looks at the laboratory-scale recovery of iron oxides (alpha Fe2O3 type) through bio-oxidation with Thiobacillus ferrooxidans of the ferrous sulphate contained in steel industry sulphuric pickling liquors. This is done by calcining iron sulphates and iron and ammonium sulphates obtained from the crystallization of the oxidized solution. The products of the bacterial reaction and the iron oxides are then studied according to calcination temperature. The process carried out produced 50 kg of alpha Fe2O3 per m3 of waste pickling liquor at 700 degrees C with 99.8% weight iron recovery.

Ferrous Compounds↗

PubMed1993

Colostrum composition in adolescent mothers.

Colostrum of high and low (LSEL) socioeconomic level adolescent mothers was analyzed to determine the potential influence of adolescence on colostrum's chemical composition. Concentrations of total fat, energy, total protein, immunoglobulin A (IgA), immunoglobulin M (IgM), immunoglobulin G and fatty acids were compared to those of adult mothers. The colostrum of adolescent mothers showed significantly higher levels of IgA and IgM compared to that of adults. Concentrations of lauric, myristic, and palmitic acids were lower in the group of LSEL adolescents, when compared to those of adult mothers of the same socioeconomic level, probably due to lower lipogenic activity in the former. High levels of stearic and oleic acids were found in LSEL adolescents in comparison to LSEL adults, despite similar dietary habits. Our results show that breast-feeding by adolescent mothers of any socioeconomic level is as indicated as that by adult mothers.

Adolescent↗

PubMed1991

Fat and protein composition of mature milk in adolescents.

The levels of certain components, notably total protein, total fat, energy, and fatty acids, of mature milk from 48 adolescent and 44 adult mothers was studied. These two groups were subdivided into high and low socioeconomic level (SEL). All mothers were primiparous, eutrophic, and with term pregnancy; and their newborns weighted over 2500 g at birth. The age factor appeared to have significant influence on the concentration of total protein, with higher levels in the group of adolescent mothers possibly as a compensatory mechanism to maintain the caloric value of the milk. The fatty acid content was altered significantly by the SEL probably due to the direct effect of maternal diet. The milk in adolescent mothers of low SEL demonstrated higher concentration of lauric and myristic acids, while the milk in low SEL adults contained higher proportions of linoleic and linolenic acids. The milk in adult mothers of high SEL demonstrated higher concentrations of palmitic, palmitoleic, and oleic acids. The different feeding habits of two socioeconomic groups may explain these results. The regular intake of soya oil, corn oil, and margarine by the urban population in general resulted in higher levels of linoleic acid in the milk of all groups studied.

Adolescent↗

PubMed1985

Effects of acetone in heparin on the multiple inert gas elimination technique.

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.

Acetone↗

PubMed1984

The mechanisms of arterial hypoxemia during hemodialysis.

Hypoxemia during hemodialysis has variously been attributed to worsening ventilation-perfusion (VA/Q) relationships, alveolar hypoventilation combined with a reduced respiratory quotient, increased right-to-left shunting, and diffusion impairment. It is difficult to separate out these various effects, which explains lack of agreement in the literature. To more critically evaluate the causes of hypoxemia during hemodialysis, we used a multiple inert gas elimination technique to determine the distribution of ventilation-perfusion ratios during hemodialysis in 8 patients with chronic renal failure. Measurements were made before, during (at 60, 120, and 210 min), and after hemodialysis. Whereas arterial PO2 fell from 87 to 74 mmHg by 120 min, ventilation-perfusion relationships actually improved. Cardiac output fell from 5.3 to 4.0 L/min over the same time. Alveolar ventilation, respiratory quotient, and alveolar PO2 all fell, and the alveolar arterial PO2 difference remained essentially unchanged. These findings suggest that the hypoxemia observed during hemodialysis is primarily due to a decrease in alveolar ventilation and respiratory quotient associated with removal of metabolic CO2 in the dialyzer. Secondary factors affecting arterial PO2 were the slight improvement in ventilation-perfusion relationships tending to increase it, and the decrease in cardiac output tending to decrease it. There was no evidence for diffusion impairment because the measured VA/Q inequality accounted for the degree of hypoxemia.

Arteries↗

PubMed1983

[Intrauterine malnutrition in rats. II. Study of weight and mortality of the offspring].

Rats were submitted to protein-calorie deprivation during different periods of gestation and the body weight and mortality of offspring were evaluated at 0, 28 and 90 days of age. The body weight was considered adequate (n) when the values were up to 2 SD below the mean values of control animals, or inadequate (d) when the values were below 2 SD. Rats of the control group (C) were fed ad libitum (protein 21%), and the rats of the experimental groups were fed during all gestational period (D), during the first half (D1) or second half of pregnancy (D2), with a diet containing 1% of protein, and the intake reduced to 50%. Significant differences were observed in the ponderal evolution for all experimental groups. Group D was the most damaged, with the greatest ponderal deficiency and the greatest mortality rates. Similar behavior was observed for D2. Group D1 was similar to C with the best results and the lowest mortality rate.

Animals↗

PubMed1977

One-view follow-up mammogram. Efficacy in screening for breast cancer.

To determine whether one-view mammography would be sufficiently diagnostic, 106 cases of breast cancer diagnosed by film mammography or xeromammography were reviewed independently by two radiologists. Detection rates were analyzed for the lateral view, the craniocaudal view, and then both views combined. The lateral projection resulted in an accuracy rate of 97%. Errors in false-negative reports in either projection were traced to their source.

Age Factors↗

PubMed1976