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Biomedical subjects

A Felipe

Publications and source records attributed to A Felipe.

83 records · Page 5Linked to original sources
PubMed1988

Carrier-mediated uptake of L-(+)-lactate in plasma membrane vesicles from rat liver.

Plasma membrane vesicles from rat liver transported L-lactate into the inner vesicular space. Kinetic analysis of L-lactate uptake gave a Km value of approx. 2.9 mM. Selective inhibition was found in a similar pattern to that described for the hepatic lactate carrier. L-Lactate transport was enhanced when a pH gradient was created across the plasma membrane. Vesicles obtained from fasted rats showed a higher uptake of L-lactate than those from fed rats, when incubated with physiological concentrations of L-lactate.

Alanine↗
PubMed1988

Effects of maternal hypocaloric diet feeding on neonatal rat brown adipose tissue.

Hypocaloric diet (control diet diluted 1:1 with cellulose) feeding during pregnancy caused a reduction in the body weight of rat pups at birth whereas the main parameters of brown adipose tissue composition and thermogenic activity were unaffected. When prenatally underfed rat pups were nursed by untreated dams eating control diet during lactation, early (day 4 of life) and late (day 13 of life) neonatal body weight was rehabilitated and brown adipose tissue remained essentially unchanged. When prenatally underfed rat pups were nursed by dams that were fed with the hypocaloric diet during lactation, neonatal body weight continued lower at the two mentioned days of life and the overall thermogenic capacity of brown fat (GDP binding/g body weight) was substantially depressed. The reduction of the brown fat thermogenic capacity in these pups is mainly due to a hypotrophy of the mitochondrial component of the tissue as indicated by the lowered cytochrome oxidase activity. Results indicate that mild maternal underfeeding during lactation may depress brown adipose tissue thermogenic function in neonates whereas similar hypocaloric intakes during pregnancy did not alter brown fat thermogenic capacity.

Adipose Tissue, Brown↗
PubMed1988

Effect of luminance on photopic visual acuity in the presence of laser speckle.

Visual acuity in coherent and incoherent light has been determined by using square-wave gratings of 100% contrast. Luminance was varied from 3 to 400 cd/m2. Coherent illumination resulted in a 40% loss of visual acuity. This is probably due to the masking effect of coherent spatial noise (speckle). However, the most interesting finding is the change in shape of the photopic visual-acuity-luminance function. With coherent illumination, the function is vertically displaced and of a different gradient. An increase in luminance produces a decrease in visual acuity. This indicates that the masking effect of the speckle is dependent on luminance. Two observers were used, and similar results were obtained by both.

Adult↗
PubMed1988

Visual reaction-time versus action-time.

The reaction-time for movement was found to be around 150 ms and was compared with the time required to take action while two moving lines are on a collision course. Subjects were trained to either avoid or maximize collision. They did so accurately. The action-time was about one-third the reaction-time.

Humans↗
PubMed1988

Sequential visual reaction times.

The reaction-time to a series of successive digits was measured on two subjects. After practice, it was found that whilst the reaction time to the onset of the series was constant at 150 ms, the response time to additional digits became less and less to asymptote to a level of about 50 ms. The time course of this 'chorus-line' phenomenon was studied in greater temporal detail by varying the interval in steps of 20 ms. The effect was greatest at 200 ms. Thereafter, it declined and for long intervals reached the value of a standard reaction time. On a third inexperienced subject, the learning period was established; this was about 300-400 presentations. The implications of these findings are discussed against the background of everyday visual motor behaviour.

Adult↗
PubMed1987

Reduced noradrenaline turnover in brown adipose tissue of lactating rats.

Brown adipose tissue properties as well as noradrenaline turnover in the tissue were determined in 15-day lactating rats and virgin controls. Brown adipose tissue thermogenic activity was reduced in lactating rats as shown by a decrease in weight, cytochrome oxidase activity and mitochondrial GDP-binding. The noradrenaline turnover rate was lower in brown adipose tissue from lactating rats. It is suggested that diminished sympathetic activity in brown adipose tissue may be a major cause of the reduced tissue thermogenic activity during lactation.

Adipose Tissue, Brown↗
PubMed1986

Sequential changes in brown adipose tissue composition, cytochrome oxidase activity and GDP binding throughout pregnancy and lactation in the rat.

The sequential appearance of changes in interscapular brown adipose tissue composition, cytochrome oxidase activity and GDP binding was studied throughout pregnancy and lactation in the rat. Brown adipose tissue was hypertrophied during pregnancy because of progressive lipid accumulation, whereas its mitochondrial component and GDP binding to brown fat mitochondria were unchanged. In early lactation (day 5) there was a decrease in the overall GDP binding to brown fat only because of the lower mitochondrial protein content. In late stages of lactation (days 10 and 15), the amount of tissue and its mitochondrial protein content were minimal and the GDP binding per mitochondrial protein decreased substantially. Scatchard analysis in day-15-lactating rats indicated a large decrease in GDP binding sites without any changes in affinity. It is concluded that the diminished thermogenic activity of brown fat in lactation is attained through changes at different structural levels of the tissue occurring in a characteristic sequential trend; first a reduction in its mitochondrial component, and only later, at mid-lactation, a decrease in the specific mitochondrial proton conductance pathway activity.

Adipose Tissue, Brown↗
PubMed1986

Brown adipose tissue activity in hypocaloric-diet fed lactating rats.

Hypocaloric diet feeding reduced the mitochondrial protein content and whole tissue GDP-binding in interscapular brown adipose tissue from both virgin and lactating rats. A reduction in brown fat lipoprotein lipase activity was also detected in underfed virgin and lactating animals. These results indicate that lactation in the rat, even though it produces a reduction in brown fat activity, does not impair the capacity of the tissue to respond to a diminished caloric intake by lowering its activity further.

Adipose Tissue, Brown↗
PubMedDate not supplied

[The radiotherapy control of cervical adenopathies in undifferentiated epithelial tumors of the head and neck. The prognostic factors].

A total of 90 patients with undifferentiated carcinomas tumors the head and neck with clinical neck nodes who received intended radical irradiation, were studied by means of a multivariant analysis of 9 variables which defined cervical lymph node disease in oder to determine the prognostic factors for the control of the above mentioned adenopathy. The factors were as follows: lymph node response post-irradiation (p = 0.0000), condition of the primary (controlled-non controlled) (p = 0.0208).

Carcinoma↗