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Biomedical subjects

M Fernandez

Publications and source records attributed to M Fernandez.

13 recordsLinked to original sources
PubMed1992

Influence of lighting conditions on toxicity and genotoxicity of various PAH in the newt in vivo.

We evaluated the influence of near-ultraviolet light (UVA) on the cytotoxicity and genotoxicity of 7 polycyclic aromatic hydrocarbons (PAH) in larvae of the amphibian Pleurodeles waltl. Benz[a]anthracene (BA), 7,12-benz[a]anthraquinone (BAQ) and anthracene (Ac) proved to be lethal at low doses (some ppb), and the following order of genotoxicity was observed: BA approximately BAQ > DMBA > DMA (9,10-dimethylanthracene). Ac, AQ (9,10-anthraquinone) and DBA (dibenz[a,h]anthracene) were not found to be clastogenic. In the larvae reared in normal conditions (subdued natural daylight/darkness alternation) or in continuous darkness, the BA derivatives were shown to be more genotoxic than BA itself: DMBA > BAQ > BA; BA (> or = 187.5 ppb) slightly increased the level of micronuclei in circulating erythrocytes, while DMBA was strongly clastogenic, in line with their reported carcinogenicity. In other experiments, rearing media alone (i.e., water containing BA, BAQ or DMBA) were UVA-irradiated for 24 h, and then tested on larvae in the dark ('IR-UV/dark' conditions). Photodegradation of BA (50 and 100 ppb) gave rise to clastogenic products. By contrast, DMBA (12.5, 25 or 50 ppb) was destroyed by UVA, and we suggested that any potentially mutagenic photoproducts formed were not in sufficient amounts to yield a positive response in the newt micronucleus test.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Protein C, protein S and C4b-binding protein in neonatal severe infection and septic shock.

We have studied the behaviour of total protein S, free protein S, protein C and C4b-binding protein fifteen neonates with severe infections, eight with septic shock and in a group of ten healthy newborns. Protein C was decreased in shock and septic patients, but only the shock group showed significant differences compared to normal neonates. Total protein S was normal in both groups of patients, although free protein S had significantly lower values in shock and nonshock infants. C4b-binding protein was higher than normal in septic and shock patients compared to the control group. Decreased values of protein C and free protein S can be explained by the activation of coagulation and their subsequent consumption. On the other hand, the increased levels of C4b-binding protein can affect the distribution of protein S in plasma, producing a shift in protein S to the complexed inactive form. These findings can contribute to an increased risk of microthrombosis during neonatal sepsis.

Carrier Proteins↗
PubMed1979

Correction of the maternal effect linked to the ac mutation, by injury of the egg, in the salamander Pleurodeles waltlii.

At the gastrula stage, deep irregular furrows appear on the animal hemisphere in embryos arising from ac/ac females and characterize a maternal effect (Beetschen, 1970). Disturbed morphogenetic movements (epiboly and invagination) frequently elicit exogastrulation or anomalies of later embryonic development. Pricking the animal hemisphere of the uncleaved egg with a micropipette prevents the occurrence of anomalies during gastrulation and neurulation in many embryos. Injection of normal oocyte nuclear sap or of normal egg cytoplasm into mutant female eggs does not improve that result. The partial correction of the maternal effect therefore appears to be consecutive to the injury of the cortical cytoplasm and/or the plasma membrane. Assuming that activation could be deficient, an electric shock was applied to freshly laid fertilized mutant eggs. It did not correct ectodermal anomalies but nevertheless seemed to increase the corrective effect of pricking when both treatments were applied.

Animals↗
PubMed1977

Immobilised monomers of human liver arginase.

Human liver arginase (L-arginine amidinohydrolase, EC 3.5.3.1) was immobilised by attachment to nylon with glutaraldehyde as a crosslinking agent. Incubation of the immobilised tetrameric enzyme with EDTA followed by dialysis resulted in the dissociation of the enzyme into inactive matrix-bound and solubilised subunits. Both species recovered enzymatic activity after incubation with Mn2+, and the activity of the reactivated matrix-bound subunits was nearly 25% of that shown by the enzyme initially attached to the support in the tetrameric form. When the reactivated bound subunits were incubated with soluble subunits in the presence of Mn2+, they 'picked-up' from the solution an amount of protein and enzymatic activity almost identical to that initially lost by the immobilised tetramer after the dissociating treatment with EDTA. This occurred only in the presence of Mn2+. It is suggested that the reactivation of the subunits of arginase involves the initial formation of an active monomer, which then acquires a conformation that favours a reassociation to the tetrameric state.

Arginase↗
PubMed1975

Bacteriology of the gallbladder bile in normal subjects.

A bacteriologic analysis of the gallbladder bile in eighty patients who underwent operation was performed in a prospective study. In all twenty patients with a normal gallbladder as assessed by oral cholecystography and intraoperative palpation, cultured were negative. Among patients with chronic cholecystitis only 30 per cent had positive bile cultures and this rose to 47 per cent among patients with acute cholecystitis.

Adult↗
PubMed1975

The Gamut approach to scintigram interpretation--diagnostic aid and teaching method.

A Gamut is defined as a complete list of anything. As utilized here, it indicates a complete list of the possible causes of a particular scintigram finding. The procedure for developing a Gamut is discussed, ant its use as a tool for instructing residents in nuclear medicine is described. Sample Gamuts are presented and the Gamut approach to scintigram differential diagnosis is described.

Internship and Residency↗
PubMed1975

[The role of temperature in phenotypic expression of amphibian embryos Pleurodeles waltlii homozygous for the heat-sensitive mutation ac (caudal ascites)].

1. At the feeding stage (st. 38), a high percentage (79%) of Pleurodeles homozygous ac/ac larvae show bent tails after a persistent ascitic blister in the dorsal part of the fin, when embryonic development occurred at 12 degrees C; about only 25% of them are affected by abdominal and pericardic ascites; about 40% can feed and survive. The larval phenotype is very different when embryonic development occurred at 23 degrees C, in which case tail growth appears to be normal, but 95% larvae die, due to ascitic fluid collection in the abdominal and heart regions, marked anaemia and microcephaly. 2. The exchange of posterior neural plates and dorso-lateral epidermis between normal and mutant neurulae has shown that the localization of the blister in the dorsal fin is not dependent on autonomous properties of the mutant dorsal tissues, but should be considered as resulting from general disturbances in the mutatnt organism. 3. Experiments were performed, involving a temperature shift from 12 to 23 degrees

Age Factors↗
PubMedDate not supplied

Further experience with the syndromes produced by coca paste smoking.

Cocaine base or white coca paste was smoked heavily by 188 patients who came to four hospitals of Lima, Peru. The length of hospitalization varied from two days to six months. All patients were admitted because coca paste smoking had become a serious problem for their health or for social adjustment. Coca paste was smoked mixed with tobacco or marihuana. The main symptoms were anxiety mingled with euphoria and a rapidly developing compulsion to continue smoking. Frequently the patients developed irritability, illusions, hallucinations. When the use of the drug was heavy and continued for many hours or several days, the patients developed successively four stages of psychological reaction: euphoria, dysphoria, hallucinosis, and acute paranoid psychosis. The main symptoms and signs of all of these phases are discussed.

Adolescent↗