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B K Jha

Publications and source records attributed to B K Jha.

17 recordsLinked to original sources
PubMed2006

Role of 2-5A-dependent RNase-L in senescence and longevity.

Senescence is a permanent growth arrest that restricts the lifespan of primary cells in culture, and represents an in vitro model for aging. Senescence functions as a tumor suppressor mechanism that can be induced independent of replicative crisis by diverse stress stimuli. RNase-L mediates antiproliferative activities and functions as a tumor suppressor in prostate cancer, therefore, we examined a role for RNase-L in cellular senescence and aging. Ectopic expression of RNase-L induced a senescent morphology, a decrease in DNA synthesis, an increase in senescence-associated beta-galactosidase activity, and accelerated replicative senescence. In contrast, senescence was retarded in RNase-L-null fibroblasts compared with wild-type fibroblasts. Activation of endogenous RNase-L by 2-5A transfection induced distinct senescent and apoptotic responses in parental and Simian virus 40-transformed WI38 fibroblasts, respectively, demonstrating cell type specific differences in the antiproliferative response to RNase-L activation. Replicative senescence is a model for in vivo aging; therefore, genetic disruption of senescence effectors may impact lifespan. RNase-L-/- mice survived 31.7% (P<0.0001) longer than strain-matched RNase-L+/+ mice providing evidence for a physiological role for RNase-L in aging. These findings identify a novel role for RNase-L in senescence that may contribute to its tumor suppressive function and to the enhanced longevity of RNase-L-/- mice.

Aging↗
PubMed2000

Interactions between a lipase and charged surfactants--a comparison between bulk and interfaces.

The interaction between a charged surfactant and a lipase has been investigated by several methods. Interactions in aqueous bulk phase was studied by NMR and by microcalorimetry. Surface tension and neutron reflectivity were used for studies at the air-water interface. Interactions at the interface between a hydrophobic solid surface and water was investigated by ellipsometry. The results obtained are as follows. The cationic surfactant, tetradecyltrimethylammonium bromide (iodide in the NMR experiments), showed strong interaction at the air-water and the hydrophobic solid-water interfaces but no clear indication of an interaction in bulk phase was seen. The anionic surfactant showed no interaction with the lipase neither at the interfaces, nor in bulk. The difference in behavior of the system cationic surfactant-lipase in bulk and at the interfaces may be due to the change in enzyme conformation that is known to occur at interfaces between water and an apolar phase.

Calorimetry↗
PubMed1979

The prevalence and nature of anemia among apparently normal subjects in Fiji.

A total of 4939 apparently healthy Fijian and Indian subjects living in Fiji were tested for anaemia by determination of the microhaematocrit of a sample of capillary blood. The prevalence of anaemia during childhood varied with age but was similar for Fijians and Indians of either sex. The overall prevalences were: 0-4 years, 20.3%; 5-9 years, 3.7%; 10-14 years, 23.5%. The prevalence of anaemia among Indian women (33.3%) was substantially higher than that for Indian men (6.9%), Fijian women (8.1%) or Fijian men (6.8%). Iron deficiency was the most common cause of anaemia and was established by laboratory studies in 203 (68%) of 298 anaemic subjects who were followed up. Iron deficiency was an important aetiological factor in 91 (93%) of 98 subjects with moderate or severe anaemia. Folate deficiency was found, usually in combination with iron deficiency, in 44 or 141 anaemic indian adults were followed up. Folate deficiency was uncommon in Fijian adults and among children of either race. Two cases of nutritional vitamin B12 deficiency, one case of pernicious anaemia, 6 cases of heterozygous thalassaemia and one case of heterozygous haemoglobin E were found among the anaemic Indian subjects. No cases of vitamin B12 deficiency anaemia, thalassaemia or haemoglobinopathy were detected among the Fijians. In 5 Indians and 7 Fijians the anaemia was associated with an underlying chronic disorder. This study emphasizes that in Fiji, as in other developing countries, nutritional anaemia is prevalent among asymptomatic subjects. Iron deficiency is by far the most common cause.

Adolescent↗
PubMedDate not supplied

Prevalence of Moraxella catarrhalis infections of the lower respiratory tract in elderly patients.

OBJECTIVES: To determine: *rate of isolation of Moraxella catarrhalis in elderly patients having lower respiratory tract infection *The antibiotic susceptibility pattern of Moraxella catarrhalis isolates. *The predisposing factors responsible for Moraxella catarrhalis infections of lower respiratory tract. MATERIAL AND METHOD: This is a prospective study carried out at Manipal Teaching Hospital, Pokhara during May 2002 to April 2003. A total of 716 sputum samples collected from patients with suspected lower respiratory tract infection were investigated. The samples were subjected to Gram stain, culture and sensitivity. Sputum samples were inoculated on blood and chocolate agar and incubated at 37 degrees C for 18 to 24 hours in candle jar containing 3-5% Co2. For the identification of bacterial isolates, the cultural and colonial characteristics were recorded and identified with the use of biochemical test. The susceptibility of bacterial isolates to antimicrobial agent was performed following Kirby-Bauer method. RESULT: Out of the 716 samples, 355 (49.58%) grew normal commensals of the upper respiratory tract. Respiratory pathogens were recovered from 361 (50.41%) samples. The most common respiratory pathogen was H. influenzae (26. 86%), followed by S. pneumoniae (21.16%). Moraxella catarrhalis accounted for 6.90%. Rate of isolation of Moraxella catarrhalis was higher in males than in females. Out of 25 isolates 16 were from males and 9 were from females. Frequency of isolation of Moraxella catarrhalis was more frequently seen in age group 61-70 years. It was most commonly recovered in winter. The most effective antibiotics were amoxicillin-clavulanate and ceftriaxone and least was ampicillin. CONCLUSION: Moraxella catarrhalis isolation from sputum especially in persons above 60 years of age and in the absence of other well established pathogens should not be disregarded as they can cause lower respiratory tract infection in these individuals.

Age Distribution↗