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K Shetty

Publications and source records attributed to K Shetty.

26 records · Page 2Linked to original sources
PubMed1999

The risk for cancer or dysplasia in ulcerative colitis patients with primary sclerosing cholangitis.

OBJECTIVES: Recent studies have implicated primary sclerosing cholangitis (PSC) as a risk factor for colorectal cancer (CRC) in ulcerative colitis (UC). Our study was designed to define both the risk and the risk factors for CRC or dysplasia in a large UC cohort with PSC. METHODS: Patients with UC and PSC were compared with a random sample of UC controls without PSC. Patients were analyzed from the inception of disease until an outcome or censor. RESULTS: Thirty-three (25%) of 132 UC patients with PSC developed CRC or dysplasia compared with 11 (5.6%) of 196 controls (adjusted relative risk 3.15, 95% confidence interval 1.37-7.27). Possible risk factors were chronic disease activity and lack of folate supplementation. Of 17 CRCs in the PSC group, 76% occurred proximal to the splenic flexure and 35% presented at an advanced stage, compared with one of five (20%) CRCs in controls being proximal and none being advanced. Six (4.5%) PSC patients, and no controls, died of CRC (p < 0.01). CONCLUSIONS: UC patients with PSC are at increased risk of developing CRC or dysplasia. Chronically active disease may be a risk factor, whereas folate could have a protective effect. CRCs associated with PSC are more likely to be proximal, to be diagnosed at a more advanced stage, and to be fatal.

Adult↗
PubMed1998

Solid-State Production of Beneficial Fungi on Apple Processing Wastes Using Glucosamine as the Indicator of Growth.

Three Trichoderma species, a Penicillium species, and a Rhizopus species were grown on apple pomace at 25 degrees C through solid-state fermentation. The effects of CaCO(3), water, and nitrogen sources on the growth of selected fungi on apple pomace were investigated. Soluble protein and glucosamine contents of fermented pomace were measured as the parameters of fungal growth. The maximum growth of all fungi was established on apple pomace supplemented with 0.05 g of CaCO(3), 2 mL of water, and 0.05 g of NH(4)NO(3) or 0.3 mL of fish protein hydrolysate per gram of pomace. The optimal water activity of the medium for fungal growth was 0.96 at 25 degrees C. This research has provided a clear indication for using glucosamine as a proper indicator of fungal growth in heterogeneous solid-state systems. It also shows potentials for bioconversion of apple processing wastes by beneficial fungi into valuable bioinoculants that are being targeted for agricultural and environmental applications.

Journal Article↗
PubMed1997

Defining the chemical groups essential for Tetrahymena group I intron function by nucleotide analog interference mapping.

Improved atomic resolution biochemical methods are needed to identify the chemical groups within an RNA that are essential to its activity. As a step toward this goal, we report the use of 5'-O-(1-thio)inosine monophosphate (IMP alphaS) in a nucleotide analog interference mapping (NAIM) assay that makes it possible to simultaneously, yet individually, determine the contribution of almost every N2 exocyclic amine of G within a large RNA. Using IMP alphaS, we identified the exocyclic amines that are essential for 5' or 3' exon ligation by the Tetrahymena group I intron. We report that the amino groups of three phylogenetically conserved guanosines (G111, G112, and G303) are important for 3' exon ligation. The amine of G22, as well as the amines of the other four guanosines within the P1 helix, are essential for ligation of the 5' exon. Previous work has shown that point mutation of either G22 or G303 to an adenosine (A) substantially reduces activity. Like inosine, adenosine lacks an N2 amino group. Interference rescue of the G22A and G303A point mutations was detected at the site of mutation by NAIM using 5'-O-(1-thio)diaminopurine riboside monophosphate (DMP alphaS), an adenosine analog that has an N2 exocyclic amine. The G22A point mutant could also be rescued by incorporation of DMP alphaS at A24. By analogy to genetics, there are interference phenotypes comparable to loss of function, reversion, and suppression. This method can be readily extended to other nucleotide analogs for the analysis of chemical groups essential to a variety of RNA and DNA activities.

Animals↗
PubMed1997

The Child-Pugh classification as a prognostic indicator for survival in primary sclerosing cholangitis.

Clinical decisions in primary sclerosing cholangitis (PSC) depend upon understanding its variable natural history. Several prognostic models for survival have been developed. We explored the Child-Pugh Classification (CPC) to determine if it predicts survival as well as a disease-specific model (DSM). We identified 208 PSC patients who satisfied established criteria. Prognostic variables were measured from the first visit. Kaplan-Meier survival estimates were obtained for CPC twice, once censoring observations at orthotopic liver transplantation and again considering orthotopic liver transplantation as a failure. A stepwise Cox proportional hazards-model was used to identify the factors associated with mortality. For 208 patients, the mean follow-up was 70 months (SD + 55). Kaplan-Meier 7-year survivals for CPC A, B, and C were 89.8%, 68%, and 24.9%, respectively (P < .001). The Cox model identified CPC and age as the most significant predictors of mortality. Adding the DSM risk score did not significantly improve the fit of the model (P = .75). The following were concluded: 1) CPC is a powerful predictor of survival in PSC; 2) DSM does not enhance the predictive ability of CPC; and 3) CPC may be used as an alternative to the DSM in research studies and clinical decision-making.

Adult↗
PubMed1997

Effect of selected polysaccharide-producing soil bacteria on hyperhydricity control in oregano tissue cultures.

Hyperhydricity, or vitrification, is a physiological malformation affecting tissue culture-generated plants. This malformation is associated with excessive hydration and poor lignification and results in poor regeneration of plants. We have tested hyperhydricity prevention in oregano by several nonspecific polysaccharide-producing rhizosphere bacteria. Among these bacteria, Pseudomonas mucidolens and another Pseudomonas sp. prevented hyperhydricity and improved acclimation of oregano clones. These two bacteria have more advantages for commercial applications than Pseudomonas strains isolated previously from oregano.

Journal Article↗
PubMed1986

Production of l-Phenylalanine from Starch by Analog-Resistant Mutants of Bacillus polymyxa.

p-Fluorophenylalanine-resistant mutants of starch-degrading Bacillus polymyxa ATCC 842, generated by ethyl methanesulfonate mutagenesis followed by incubation with caffeine, overproduced small amounts of l-phenylalanine (l-phe) from starch. A beta-2-thienylalanine-resistant mutant (BT-7) derived from p-fluorophenylalanine mutant (C-4000 FP-4) and resistant to both p-fluorophenylalanine and beta-2-thienylalanine produced 0.5 g of l-phe and 0.15 g of l-tyrosine per liter from 10 g of starch per liter when growing in a minimal medium. trans-Cinnamic acid (CA) was also excreted by both mutants, indicating the possibility of l-phenylalanine ammonia-lyase-induced deamination of l-phe to CA. The amount of l-phe-derived CA detected in BT-7 was less compared with mutant C-4000 FP-4. CA production was induced in the parent only when l-phe was used as a sole nitrogen source. Time of CA production in the two mutants could be delayed by addition of other nitrogen sources, an indication of possible l-phenylalanine ammonia-lyase inhibition or repression. The presence of l-phenylalanine ammonia-lyase in B. polymyxa mutant C-4000 FP-4 was confirmed by assays of cell-free extracts from cells grown in starch minimal medium containing l-phe as the sole nitrogen source. Preliminary studies of the regulation of deoxy-d-arabino-heptulosonate-7-phosphate synthase and prephenate dehydratase in the wild-type strain showed that deoxy-d-arabino-heptulosonate-7-phosphate synthase was subject to feedback inhibition by l-phe, l-tyrosine, and l-tryptophan. Inhibition by each amino acid was to a similar extent singly or in combination at a 0.5 mM level of each amino acid. Prephenate dehydratase was feedback inhibited by l-phe, but not by l-tyrosine or l-tryptophan or both. In the double analog-resistant mutant BT-7, deoxy-d-arabino-heptulosonate-7-phosphate synthase had specific activity similar to that in the wild type, and the enzyme was still subject to feedback inhibition. However, prephenate dehydratase had increased specific activity and it was also insensitive to feedback inhibition by l-phe. The overproduction of aromatic amino acids by BT-7 was thought to be due, at least in part, to deregulation of feedback inhibition of prephenate dehydratase. Chorismate mutase was not subject to feedback inhibition in the wild type and was unaffected in the mutant.

Journal Article↗