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Biomedical subjects

V Greene

Publications and source records attributed to V Greene.

9 recordsLinked to original sources
PubMed1998

Oral lesions among women living with or at risk for HIV infection. HIV Epidemiology Research Study (HERS) Group.

PURPOSE: Our objectives were to compare the prevalence of oropharyngeal mucosal lesions among human immunodeficiency virus (HIV) seropositive and demographically similar seronegative women, and to determine the association of oral lesions with immunosuppression, substance abuse, use of medications, and utilization of dental services. POPULATION AND METHODS: Participants in a multicenter, longitudinal cohort study of HIV infection in women were evaluated at baseline by interview, physical examination, and laboratory studies. RESULTS: Oropharyngeal pathology was found in 40% of seropositive and 23% of seronegative women. Oral candidiasis was identified in 15% of seropositive and 3% of seronegative women. Among seropositive women, history of previous oral candidiasis, lower CD4 lymphocyte counts, and current antibiotic use were associated with oral candidiasis. Hairy leukoplakia was identified in 5% of seropositive women and was significantly associated with lower CD4 lymphocyte counts. Gingival erythema and ulcerative gingivitis were found in 23% of participants overall, but were unrelated to HIV serostatus or CD4 lymphocyte count. Substance abuse, lack of dental care, and African-American race were associated with gingival pathology. CONCLUSION: The high prevalence of oral lesions among HIV seropositive and at-risk seronegative women underscores the need for routine oral examination and targeted treatment of this population.

AIDS-Related Opportunistic Infections↗
PubMed1997

Natural history of Giardia lamblia and Cryptosporidium infections in a cohort of Israeli Bedouin infants: a study of a population in transition.

The natural history of Giardia lamblia and Cryptosporidium infections were determined in a cohort of 164 Bedouin children, from a population not previously studied, which is in transition from nomadism to a settled life style. Stools were sampled monthly from birth to two years of age and at all diarrhea episodes. The risk of infection with G. lamblia and Cryptosporidium infection by age two was 91.5% and 48.8%, respectively. Cryptosporidium prevalence was 3-4% at all ages, whereas G. lamblia prevalence was > 30% after age one. Giardia lamblia and Cryptosporidium asymptomatic detection rates were high, 28.5% and 1.6%, respectively. Detection of G. lamblia was higher in diarrhea episode samples obtained before six months of age, but after that age and overall, the detection was lower than in nondiarrhea samples (odds ratio [OR] = 0.8, 95% confidence interval [CI] = 0.7-0.9, P < 0.05). Detection rates of C. parvum were higher in episode-related samples in all age groups (OR = 2.8, 95% CI = 1.9-4.2, P < 0.05) and infections in boys were more frequently symptomatic than in girls. While G. lamblia does not appear to be a consistent pathogen in this population where it is hyperendemic, Cryptosporidium has been shown to be an important cause of diarrhea in young children in the community.

Adolescent↗
PubMed1995

Sequence and structure requirements for Drosophila tRNA 5'- and 3'-end processing.

Eukaryotic tRNAs are processed at their 5'- and 3'- ends by endonucleases RNase P and 3'-tRNase, respectively. We have prepared substrates for both enzymes, separated the activities from a Drosophila extract, and designed variant tRNAs to assess the effects of sequence and structure on processing. Mutations affect these reactions in similar ways; thus, RNase P and 3'-tRNase probably require similar substrate structures to maintain the catalytic fit. RNase P is more sensitive to substrate substitutions than 3'-tRNase. In three of the four stems, one substitution prevents both processing reactions while the opposite one has less effect; anticodon stem substitutions hardly affect processing, and double substitution intended to restore base pairing also restore processing to the wild type rate. Structure probing suggests that tRNA misfolding sometimes coincides with reduced processing. In other cases, processing inhibition probably results from specific unfavorable stem appositions leading to local helix deformation. A single T loop substitution disrupts the tertiary D-T loop interaction and reduces processing. We have thus begun mapping tRNA processing determinants on the global, local, and tertiary structure levels.

Animals↗
PubMed1994

Point mutations distal to the processing site affect Drosophila pre-5 S RNA processing. Long range cooperation and a breathing model.

Drosophila pre-5 S RNA, which consists of five conserved stem-loop domains and a 15-nucleotide 3' tail, is 3'-end processed to 120 nucleotide mature 5 S RNA before ribosome assembly. Large deletions in stems II and III, all of stems IV and V, and loop C prohibit Drosophila 5 S RNA processing; deletion of stem IV and half of V does not (Preiser, P. R., and Levinger, L. (1991a) J. Biol. Chem. 266, 7509-7516). Several point mutations in stem I reduce, while certain neighboring sequence changes stimulate, processing (Levinger, L., Vasisht, V., Greene, V., and Arjun, I. (1992) J. Biol. Chem. 267, 23683-23687). Herein we extend this 5 S RNA fine structure analysis to regions farther from the processing site. Most point mutations in loop B, stem III, and loop C severely inhibit processing. One loop C substitution stimulates processing; when combined with stimulatory sequence changes in stem I and loop A, these dispersed mutations improve processing manyfold, perhaps by stabilizing a required conformation or strengthening a protein-binding site. Central stem II sequence changes inhibit processing; several adjacent sequence substitutions which weaken base pairing improve processing. Combining these results with earlier work from stem I and loop A, we hypothesize that slight reduction in base pairing may improve groove access of polypeptide chains to essential contact positions.

Animals↗
PubMed1992

The effects of stem I and loop A on the processing of 5 S rRNA from Drosophila melanogaster.

The 135-nucleotide Drosophila melanogaster 5 S RNA precursor is processed by removal of 15 nucleotides from its 3' end before incorporation into the large ribosomal subunit. Mature 5 S RNA consists of five helical stem-loops; stem IV and part of V are dispensable, whereas stem III and the 1/118 G-C base pair closest to the processing site at nucleotide 120 are required for processing (Preiser, P., and Levinger, L. (1991) J. Biol. Chem. 266, 7509-7516; Preiser, P., and Levinger, L. (1991) J. Biol. Chem. 266, 23602-23605). We have investigated the effects of stem I and loop A transversions, transitions, selected additions and deletions on 5 S RNA processing. Stem I single substitutions generally prevent processing, whereas compensatory double substitutions restore a range of processing rates. Proximal to the processing site, stem I double substitutions inhibit processing. In the distal portion of stem I and loop A, the processing effect of paired sequence changes varies widely in an irregular pattern. The 7/112 GU pair and nucleotide 13A least tolerate sequence changes; several mutations clustered close to the stem I-loop A boundary stimulate processing. We interpret these results in terms of the RNA helix path and possible RNA-protein contacts.

Animals↗
PubMed1988

Evidence of a probable role for 25-hydroxyvitamin D in the regulation of human calcium metabolism.

1,25-Dihydroxyvitamin D [1,25-(OH)2D] is the principal mediator of the biologic effects of vitamin D. We showed previously that obese white subjects have low serum vitamin D and 25-hydroxyvitamin D (25-OHD) with increased serum-immunoreactive parathyroid hormone (PTH) and 1,25-(OH)2D, low urinary calcium, and increased urinary cyclic adenosine 3',5'-monophosphate (cyclic AMP) compared with nonobese white individuals. To determine whether 25-OHD modulates calcium metabolism, the effects of 25-OHD3, 40-100 micrograms/day for 9 days, were compared in seven obese and seven nonobese white subjects who were between the ages of 20 and 34 years. Each of them was hospitalized on a metabolic ward and given a constant daily diet that contained 400 mg calcium, 900 mg phosphate, and 18 mEq magnesium. Whereas 25-OHD3 increased mean serum 25-OHD from 7 +/- 1 to 37 +/- 5 ng/ml (P less than 0.01) and urinary calcium from 102 +/- 18 to 146 +/- 17 mg/day (P less than 0.001) and decreased mean serum 1,25-(OH)2D from 40 +/- 2 to 28 +/- 2 pg/ml (P less than 0.01) and urinary cyclic AMP from 3.23 +/- 0.57 to 2.00 +/- 0.17 nM/dl GF (P less than 0.05), it did not change mean serum calcium, ionized calcium, phosphate, magnesium, immunoreactive PTH or urinary phosphate, or creatinine clearance in the obese subjects. In contrast, 25-OHD3 increased mean serum 25-OHD from 16 +/- 1 to 46 +/- 4 pg/ml (P less than 0.001) but did not alter mean serum 1,25-(OH)2D or urinary calcium or cyclic AMP in the nonobese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗