Biomedical subjects

N Motta

Publications and source records attributed to N Motta.

18 recordsLinked to original sources

PubMed2001

Biological screening of plants of the Venezuelan Amazons.

A total of 21 extracts derived from 17 different plant species collected in Venezuelan Amazons have been tested for the following biological activities: cardiovascular activity, brine shrimp lethality, and inhibitory effects on the hydrolysis of glucose-6-phosphate in intact and disrupted microsomes. Eight extracts diminished rat blood pressure with or without changes in heart rate. The fruit extract of Swartzia leptopetala and the leaf and twig extract of Connarus lambertii resulted in death of experimental animals. The majority of extracts (17 extracts) showed significant toxicity against Artemia salina. Concerning the hydrolysis of glucose-6-phosphate, better inhibitory effects were observed in intact microsomes than in disrupted ones for all the extracts, suggesting that these extracts intervene with variable potency in glucose-6-phosphate transport through the microsomal membrane.

Animals↗

PubMed2001

Characterisation of hepatic microsomal glucose-6-phosphatase from broiler chickens.

1. The hepatic glucose-6-phosphatase (G-6-Pase) kinetic variables from chickens were studied in intact and disrupted microsomes using two substrates: glucose-6-phosphate (G-6-P) and pyrophosphate (PPi). They were studied from embryonic life to 51 d of age. 2. The phosphohydrolase activity studied in the broiler chicken liver microsomes corresponds to a true glucose-6-phosphatase. 3. The enzyme VMAX with both substrates in intact and disrupted microsomes showed 2 maxima: one in 19-d-old embryos and the other in 9-d-old chickens. Pyrophosphatase (PPase) VMAX in intact microsomes was higher than that of the G-6-Pase at all ages studied, except in 12 d embryos and 3-d-old chicks. In disrupted microsomes the VMAX of both enzymatic activities were similar. The G-6-Pase latency was high in the 19-d-old embryos and 51-d-old chickens. 4. The KM for PPi and G-6-Pase decreased when microsomes were disrupted. In intact microsomes the G-6-P KM was low in embryos and 3-d-old chicks and later increased. On the other hand, the PPi KM in intact microsomes showed little change during the animal's life and was lower than that of G-6-P. In disrupted microsomes the KM for both substrates were similar. 5. These results suggest a sequential incorporation of the G-6-Pase system components in the endoplasmic reticulum.

Aging↗

PubMed1998

Thioacetamide effects on the polypeptidic and nucleoporin pattern and chemical composition of rat liver nuclear envelope subfractions.

The effect of the administration of seven doses of the hepatocarcinogen thioacetamide on the chemical composition of rat liver nuclear envelope subfractions: associated chromatin, nuclear membranes and pore complex-lamina fraction, is analyzed. No alteration in DNA, RNA or phospholipid content is observed after the hepatocarcinogen treatment. Electrophoretic studies of each subfraction from thioacetamide treated rats show differences in the relative proportions of some polypeptides when compared with the controls. Examination of the wheat germ agglutinin binding polypeptides of each subfraction reveals a decrease in the stain of two pore complex-lamina nucleoporins of 85 and 164 kDa and an increase in one of 93 kDa; this observation can be due to changes in the quantity and/or in the agglutinin binding capacity of the nucleoporin as a result of thioacetamide administration. In view of the participation of nucleoporins in the nucleocytoplasmic transport, the changes observed suggest a relationship between changes of some O-linked N-acetyl glucosamine polypeptides components of the nuclear pore complex and the altered transport of some RNA species observed after thioacetamide administration.

Animals↗

PubMed1994

Activated carbon paste electrodes for biosensors.

A reagentless amperometric glucose biosensor was constructed using glucose oxidase and hydroquinone (H2Q) coimmobilized in carbon paste. The sensor response was studied by amperometry and cyclic voltammetry in quiescent solutions, as well as in a flow injection apparatus. Studies were conducted as a function of surface activation and sensor working conditions such as glucose concentration, storage, aging, and reusability. Surface activation proved to be useful to improve the electro-chemical reversibility of the mediator and the analytical characteristics of the sensor. The harsh conditions of the surface pretreatment did not deactivate the enzyme. Results from the assay of a clinical sample gave a glucose concentration value of 76 +/- 6 mg/dL, which compared favorably with the expected range of 72-88 mg/dL.

Biosensing Techniques↗

PubMed1994