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Biomedical subjects

N K Menon

Publications and source records attributed to N K Menon.

At least 55 records · Page 3Linked to original sources
PubMed1984

Restriction of maternal food intake inhibits fatty acid activation in developing rat hearts.

We studied the effect of restricting the diet of pregnant and lactating rats on the beta-oxidation of fatty acids by the developing heart in suckling pups. Control pregnant rats were fed a stock diet ad libitum. For the experimental group, food was restricted to half of the control intake on the seventh day of pregnancy and continued through lactation. The pups on the restricted diet were significantly smaller than the controls. At postnatal days 5, 14 and 21, the beta-oxidation of [1-14C] palmitate by heart homogenates was determined in the presence of ATP, carnitine and CoA. At day 21, the production of 14CO2 was 60% lower in the group on the restricted diet. Consequently, the possibility of inhibiting activation or intramitochondrial transport of fatty acids by heart mitochondria was studied in vitro using [1-14C] palmitate, [1-14C] palmitoyl CoA and [1-14C] palmitoyl carnitine. With [1-14C] palmitate, the rate of 14CO2 produced was 2464 +/- 317 cpm/mg protein/min for the control and 1682 +/- 91 for the restricted diet group. With [1-14C] palmitoyl CoA and [1-14C] palmitoyl carnitine, the oxidation rate of the experimental group was similar to control values, showing clearly that the inhibition of oxidation was from a problem with activation. A significant decrease in palmitoyl CoA synthetase activity in the heart homogenates and mitochondria of the diet-restricted pups took place.

Animals↗
PubMed1983

Differences in the fatty acid profile and beta-oxidation by heart homogenates of rats fed cis and trans octadecenoic acids.

Female Wistar rats were fed a fat-free diet containing either 5% partially hydrogenated corn oil (52.2% elaidate) or 5% oleic acid (67% oleate) with 8.6% linoleate providing 1% of calories 2 weeks before mating and were maintained on this diet throughout pregnancy and lactation. Fatty acid analysis of the developing organs as well as beta-oxidation by heart homogenates with [1-14C]palmitate, [1-14C]elaidate and [1-14C]oleate of the developing male and female progeny were determined and compared with age-matched controls on a stock diet. Results show that irrespective of the cis and trans 18:1 in the diet, the maternal plasma at term contained mostly cis 18:1, with 5% trans for the rats on the trans diet. The placenta and fetal liver contained 40 and 60% less trans, respectively, than did the maternal plasma. trans 18:1 was not detected in fetal brain or heart. Regardless of diet or sex, the order of preference for the heart was palmitate greater than elaidate greater than oleate. There was an increase in the rate of beta-oxidation of all the substrates, especially in the females on the trans diet, suggesting a stimulation of one or more of the enzymes involved. Above all, the myocardium showed a unique capacity to retain n-6 and n-3 fatty acids when the levels of these decreased in the serum.

Animals↗
PubMed1981

Perinatal methylmercury intoxication: behavioral effects in rats.

Sprague-Dawley rats were subjected to perinatal (4th gestational day until Postnatal Day 21) methylmercury intoxication to determine the long-term behavioral effect of the mercury poisoning. Experimental and control animals were evaluated at 110-140 days of age. Compared to controls, the methylmercury animals demonstrated significant behavioral deficits characterized by hypoactivity and by reduced appetitive, escape, and avoidance learning.

Animals↗
PubMed1981

Effect of essential fatty acid deficiency on maternal, placental, and fetal rat tissues.

Prolonged dietary deprivation is needed to produce essential fatty acid (EFA) deficiency. But lack of EFA also impairs reproductive function. Inclusion of small amounts of linoleic acid in the diet can overcome this difficulty; further, if large amounts of oleic acid are included in the diet, this competes with the utilization of 18:2 producing EFA deficiency. Using this approach, female rats were fed a fat-free diet containing 5% oleic acid w/w (with 2-3% 18:2) as the only source of fat for 4 months. They were mated and on the 21st day of gestation, the fatty acids of fetal tissues, placenta, maternal liver and plasma were analyzed and compared to controls on a stock diet. Fetuses from the experimental group were smaller and contained higher amounts of 18:1 and 20:3 omega 9 indicating EFA deficiency. The omega 6 fatty acids in the polar lipids of placenta of the EFA-deficient group were not significantly lower than the controls, in spite of lower concentrations in the maternal plasma, suggesting a unique capacity of the placenta to concentrate omega 6 fatty acids, which in turn may be utilized for prostaglandin synthesis needed for inducing labor and other vascular changes in the fetus.

Animals↗
PubMed1980

Primary adenocarcinoma of the appendix.

Two cases of carcinoma of the appendix presenting as appendicular masses are discussed. Carcinoma of the appendix is rare and hence a pre-operative diagnosis is seldom made. Awareness of the condition would naturally arouse suspicion of its presence, especially in elderly patients who present with cute appendicitis or an appendix mass. It is known to have occurred in an appendix stump several years after the initial appendicectomy, and also in a 17-year-old patient. The need for histological examination of all appendicetomy specimens is stressed. The operation of choice is right hemicolectomy, either as a primary or as a secondary procedure. This is associated with better survival rates than when the condition is treated by appendicectomy alone.

Adenocarcinoma↗
PubMed1976

Low activities of the pyruvate and oxoglutarate dehydrogenase complexes in five patients with Friedreich's ataxia.

Since patients with Friedreich's ataxia appear to oxidize pyruvate slowly, we measured the activity of the pyruvate dehydrogenase complex in disrupted fibroblasts from four patients with this syndrome and one patient with a clinical variant. The activity was 43 +/- 4 per cent of that in 16 controls (mean +/- S.E.M., P less than 0.001). The activity of the 2-oxoglutarate dehydrogenase complex was also lower in the patients' cells than in those of controls (50 +/- 2 per cent, P less than 0.001). However, the activity of cytochrome-c oxidase was normal (126 +/- 43 per cent of controls). Mixing experiments gave no evidence of soluble enzyme inhibitors or activators, and the addition of excess substrate or cofactor did not ameliorate the deficiencies. White blood cells from one of the patients had low activities of both complexes. Mutations of these dehydrogenase complexes occur in some patients with Friedreich's ataxia and lead to abnormally low activity of an enzyme of the tricarboxylic acid cycle.

Adolescent↗
PubMed1971

Two controlled studies of the efficacy of isoniazid alone in preventing relapse in patients with bacteriologically quiescent pulmonary tuberculosis at the end of one year of chemotherapy.

An earlier report showed that, in patients with bacteriologically quiescent pulmonary tuberculosis at the end of 1 year of chemotherapy, isoniazid alone in a single daily dose of 150-200 mg, given as maintenance therapy in the second year, did not markedly prevent relapse over a 4-year period of follow-up in patients who had had residual cavitation (the "open-negative" syndrome) at 1 year, but was highly effective in patients who had not. As a result of these findings, two controlled studies, reported here, were undertaken.The first study was undertaken in patients with bacteriologically quiescent disease and residual cavitation at 1 year, and investigated the value of isoniazid in a higher daily dose (400 mg) throughout the second year; this is known to be the optimum therapeutic dose when isoniazid is prescribed alone for 1 year in the initial treatment of the disease. The second study was carried out in patients with bacteriologically quiescent disease and no residual cavitation at 1 year, and sought to determine the value of a shorter duration (6 months) of chemotherapy in the second year with a daily dose of 300 mg of isoniazid. Neither of the two isoniazid regimens was highly satisfactory, although both appeared to have had some effect in preventing relapse during the 4-year period of follow-up.

Clinical Trials as Topic↗
PubMed1971

Inactivation of isoniazid by condensation in a syrup preparation.

This paper reports the gross and rapid condensation of isoniazid in a commercial black-currant-flavoured syrup. In vitro studies showed that the condensation was due, at least partly, to the glucose contained in the syrup, paper chromatography having demonstrated the presence of D(+)-glucose isonicotinoyl hydrazone. Controlled studies in human beings showed that the absorption of isoniazid from the preparation was considerably impaired by this condensation.It is concluded that sugars such as glucose, fructose, and sucrose-especially glucose-should not be used in isoniazid syrup preparations, and it is suggested that sorbitol, a stable non-carbonyl compound, might be a suitable substitute.

Adult↗