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Biomedical subjects

R S Rajan

Publications and source records attributed to R S Rajan.

14 recordsLinked to original sources
PubMed2001

Specificity in intracellular protein aggregation and inclusion body formation.

Protein aggregation is widely considered to be a nonspecific coalescence of misfolded proteins, driven by interactions between solvent-exposed hydrophobic surfaces that are normally buried within a protein's interior. Accordingly, abnormal interactions between misfolded proteins with normal cellular constituents has been proposed to underlie the toxicity associated with protein aggregates in many neurodegenerative disorders. Here we have used fluorescence resonance energy transfer and deconvolution microscopy to investigate the degree to which unrelated misfolded proteins expressed in the same cells coaggregate with one another. Our data reveal that in cells, protein aggregation exhibits exquisite specificity even among extremely hydrophobic substrates expressed at very high levels.

Cell Line↗
PubMed2001

Chitra heart valve: results of a multicenter clinical study.

BACKGROUND AND AIM OF THE STUDY: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultra-high molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder. METHODS: Between December 1990 and January 1995, 306 patients underwent isolated aortic (AVR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr). RESULTS: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven years were 82.4+/-4.0% for AVR and 65.2+/-5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9+/-1.1% and 94.1+/-1.9%, and 92.3+/-2.8% and 82.1+/-5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5+/-4.1% after AVR, and 64.2+/-5.1% after MVR. CONCLUSION: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients.

Adolescent↗
PubMed1989

Enlarging pulmonary histoplasmoma associated with pulmonary tuberculosis.

Histoplasmosis is not a frequently reported infection from India. Similarity of its clinical and radiological features with pulmonary tuberculosis, may cause a difficult diagnostic dilemma when the two occur together. We report a case who initially presented with cavitary lesions over right lung responding well to anti tuberculosis chemotherapy but subsequently a small opacity present over the left upper zone showed a relentless increase till it attained a massive size few years later. Operative removal and histopathological examination of the mass confirmed it to be histoplasmoma. She became sputum AFB smear positive and culture negative for a short while during this period and this is explained on the basis of previous reports.

Adult↗
PubMed1986

Effect of beclomethasone dipropionate on nasal metachromatic cell sub-populations.

The effect has been investigated of local administration of beclomethasone dipropionate (BDP) on cell numbers of nasal epithelial metachromatic cell (NMC) sub-populations. Twenty-one patients with perennial allergic rhinitis were studied in four groups according to the duration of treatment or after treatment with BDP. Nasal scrapings were taken after 1 week (Group 1) or 2 weeks (Group 2) of BDP treatment, or after discontinuing BDP for 1 week (Group 3) or 2 weeks (Group 4). Cells were fixed with Mota's lead acetate or 10% buffered formalin followed by toluidine blue staining to count the number of NMC and to classify these according to morphological sub-types (basophils or mast cells). Formalin-sensitive mast cells and basophils in nasal scrapings were reduced more than formalin-resistant mast cells with BDP treatment. Formalin-sensitive mast cells were also more prompt to recover from BDP than formalin-resistant mast cells. The results suggest that the formalin-sensitive NMC is a sub-population of cells which responds to BDP treatment in allergic rhinitis.

Administration, Topical↗
PubMed1985

Heterogeneity of metachromatic cells in human nose: significance of mucosal mast cells.

The distribution and abundance of histochemically and morphologically distinct subpopulations of metachromatic cells were investigated in nasal secretions and scrapings from patients with allergic rhinitis, as well as in nasal biopsy specimens from other patients. These analyses of the metachromatic cells demonstrate that basophils and two distinct mast cell populations are present in nasal specimens. One mast cell subpopulation was analogous to the atypical mucosal mast cell of the rat and human intestine, whereas the other cell population was similar to the typical connective tissue mast cell type. In nasal scrapings greater than 80% of the metachromatic cells was mast cells, almost exclusively of the atypical "mucosal" type. However, basophils were the predominant metachromatic cell type in nasal secretions, and atypical mast cells were more abundant than typical mast cells. Few basophils were observed in biopsy specimens, but mast cells were widely distributed in various anatomic compartments. Atypical mast cells outnumbered the typical type in the epithelium and lamina propria, whereas the reverse was true in the submucosa. When the number and type of metachromatic cell in scrapings were analyzed in relation to clinical findings, there was a significant correlation with severity of symptomatology and nasal swelling and pallor. Atypical "mucosal" mast cells were the major cell type in all specimens, from those with mild to those with severe clinical findings. When the distinct spectrum of responsiveness to antiallergic compounds of atypical mast cells is considered, these observations have important therapeutic implications.

Adolescent↗
PubMed1983

Blood utilisation in open heart surgery at Green Lane Hospital.

Blood utilization in 166 patients who underwent open heart surgery over a period of three months in 1980 at Green Lane Hospital has been surveyed. Over two-thirds of the operations were for coronary artery disease. For each hospitalized patient an average of 2.55 units of homologous blood were used. Including blood products, the total demand on the blood transfusion service was 3.55 donors/patient. Regular autologous transfusion of oxygenator blood post-bypass was a major factor in reducing blood usage. No blood was used in 23% of the bypass procedures and 13% of patients did not receive any homologous blood or blood products.

Adolescent↗
PubMed1977

Detection of 4He in stratospheric particles gives evidence of extraterrestrial origin.

Whipple predicted the existence of micrometeorites, small interplanetary particles which enter the Earth's atmosphere without being melted by frictional heating. During the past 2 yr, large numbers of micrometre sized stratospheric particles have been collected which are believed to be extraterrestrial, because their elemental compositions closely match those of primitive meteorites. We report here the detection of large concentrations of 4He in some of the particles. This not only suggests an exposure to solar wind, but also indicates that these particles are true micrometeorites in the sense that they were not strongly heated by entry into the atmosphere. Strong heating would have caused much of the helium to escape.

Journal Article↗