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V Shanker

Publications and source records attributed to V Shanker.

13 recordsLinked to original sources
PubMed2004

Phenylalanine loading as a diagnostic test for DRD: interpreting the utility of the test.

Phenylalanine loading has been proposed as a diagnostic test for autosomal dominant DRD (dopa-responsive dystonia), and recently, a phenylalanine/tyrosine (phe/tyr) ratio of 7.5 after 4 h was reported as diagnostic of DRD. To test the utility of this test in another sample with DRD, we administered an oral challenge of phenylalanine (100 mg/kg) to 11 individuals with DRD and one non-manifesting gene carrier. Only 6/12 had a 4 h phe/tyr ratio of greater than 7.5, suggesting that additional parameters must be set to avoid missing the diagnosis of DRD, including the need for the plasma phenylalanine to reach a minimum level 600 in order for the test to be valid. We propose that in cases where this minimum plasma phenylalanine level is not reached, plasma tetrahydrobiopterin should be measured or alternatively other symptomatic family members should be screened.

Adolescent↗
PubMed1983

Red cell carbonic anhydrase polymorphism in Indian zebu cattle and their crossbreds.

Red cell carbonic anhydrase (Ca) types were investigated in 750 animals from three zebu, two exotic and three crossbred breeds. A Ca isozyme of slower mobility than the S isozyme was observed in four Sahiwal animals. The gene frequency of CaS, which was the predominant allele in all the breeds investigated ranged from 0.88 to 1.0.

Alleles↗
PubMed1982

Effect of dietary restriction with and without excess leucine on hepatic tryptophan oxygenase, 3-hydroxyanthranilate oxygenase and leucine aminotransferase in rats.

Tryptophan oxygenase (EC 1.13.1.12), 3-hydroxyanthranilate oxygenase (EC 1.13.1.6) and leucine aminotransferase (EC 2.6.1.6) activities were determined in livers of rats subjected to different dietary restrictions, with and without excess leucine. The activities of all three enzymes were significantly increased with undernutrition in animals not receiving excess leucine. Excess leucine with moderate undernutrition (50% ad libitum intake) further induced this effect while excess leucine with severe restriction (25% ad libitum intake) acted in the opposite direction.

3-Hydroxyanthranilate 3,4-Dioxygenase↗
PubMed1982

Effect of excess leucine on tryptophan oxygenase, 3-hydroxyanthranilate oxygenase and leucine aminotransferase in livers of young rats.

Hepatic tryptophan oxygenase (EC 1.13.1.12) 3-hydroxyanthranilate oxygenase (EC 1.13.1.6) and leucine aminotransferase (EC 2.6.1.6) activities were determined in livers of rat pups of various ages whose mothers were fed on diets with or without excess leucine. Tryptophan oxygenase activity was detectable on the 20th day in both the groups and thereafter increased with age. Low activity of 3-hydroxyanthranilate oxygenase was observed at birth, the levels increased on the 10th day and thereafter remained unaltered on both diets. Leucine aminotransferase activity was highest at birth and thereafter decreased with age. Tryptophan oxygenase and leucine aminotransferase activities were significantly higher at all ages in livers of pups born to mothers given excess leucine in their diet.

Age Factors↗
PubMedDate not supplied

Effect of dietary restriction with and without leucine supplementation on hepatic protein status in rats.

In the present study effect of dietary restriction with and without leucine supplementation was observed on body and liver weights, and liver protein status, in adult rats. Animals were fed on two diets ad lib or were on 50 per cent and 25 per cent intakes. Dietary restriction resulted in loss of body and liver weights, hepatic protein, free-alpha-amino nitrogen and RNA contents and liver cell size (liver weight/DNA ratio). When compared with the control group, the decrease in these parameters was more in the dietary restricted leucine supplemented group. However, hepatic DNA content was not changed with the change in dietary regimen. The results suggest that leucine supplementation with dietary restriction may be more harmful for the animal than dietary restriction alone.

Animals↗