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Biomedical subjects

B C Das

Publications and source records attributed to B C Das.

At least 91 records · Page 5Linked to original sources
PubMed1986

Higher incidence of spontaneous sister-chromatid exchanges (SCEs) and X-ray-induced chromosome aberrations in peripheral blood lymphocytes during pregnancy.

In vitro cultures of peripheral blood lymphocytes from human and muntjac (barking deer) females who were at an advanced stage of pregnancy (32-37 weeks pregnant women and 20-24 weeks pregnant muntjacs) showed an enhanced frequency of SCEs and X-ray-induced chromosome aberrations when compared with those of nonpregnant females. Lymphocyte cultures of nonpregnant females to which sex hormones progesterone, oestrogen and human chorionic gonadotropin (HCG) were added together exogenously also showed higher frequency of SCEs. The plausible reason(s) for such high incidence of SCEs during pregnancy is discussed.

Adult↗
PubMed1986

Investigation of an outbreak of infection with Acinetobacter calcoaceticus in a special care baby unit.

During a period of 6 months, an 'epidemic strain' of Acinetobacter calcoaceticus was isolated from 10 pre-term neonates in a special care baby unit (scbu). Of these, nine had pulmonary infections. The tenth was found to have conjunctival colonization only. The 'epidemic strain' was characterized by serotyping, biotyping, bacteriocin typing and antibiograms. An identical strain was isolated from an 'Ambu' resuscitation device but not from other environmental samples or from staff on the unit. The outbreak ceased after the colonized resuscitator was removed and an appropriate disinfection policy implemented for the replacement resuscitators.

Acinetobacter↗
PubMed1986

Revised structure of mycosubtilin, a peptidolipid antibiotic from Bacillus subtilis.

The structure of mycosubtilin, a peptidolipid antibiotic from Bacillus subtilis, was revised by FAB mass spectrometry, 2D NMR spectrometry and also by Edman degradation of the peptide resulting from the N-bromosuccinimide reaction. Four homologous beta-amino acid components were identified by capillary gas chromatography. The cyclopeptide mycosubtilin consists of seven alpha-amino acids in an LDDLLDL sequence closed by a beta-amino acid linkage similar to that found in other antibiotics of the iturin group.

Anti-Bacterial Agents↗
PubMed1985

Structure of bacillomycin F, a new peptidolipid antibiotic of the iturin group.

The structure of a new antibiotic of the iturin group, bacillomycin F, has been demonstrated. It is a mixture of homologous peptidolipids, essentially C51H80N12O14 and C52N82N12O14. The lipid moiety consists of minor isoC15, anteisoC15 beta-amino acids and major isoC16, isoC17 and anteisoC17 beta-amino acids. The peptide sequence was determined by studying the peptides obtained after mild HCl hydrolysis and by Edman degradation of bacillomycin F treated with N-bromosuccinimide. The sequence was confirmed by two-dimensional NMR spectrometry and fast-atom-bombardment mass spectrometry gave the molecular masses of the homologous compounds. Bacillomycin F is a cyclic peptidolipid; its complete structure is given in the paper.

Amino Acid Sequence↗
PubMed1985

Baseline frequency of sister-chromatid exchanges (SCE) in newborn lymphocytes and its relationship to in vivo aging in humans.

Heparinised cord blood from newborns and peripheral venous blood from three other age groups of individuals (1-75 years) have been cultured in vitro to obtain baseline frequencies of SCE and to see if the frequency of baseline SCE in vitro varies as a function of aging in vivo. The results demonstrate an age-dependent variation in the frequency of SCEs. Although the SCE frequency was lowest (5.10/cell) in 1-5-year-old infants, a significantly higher (P less than 0.001) frequency (8.97/cell) was observed in the cord blood of newborns. In old age, the level of SCE also increased. The plausible reason(s) for such observations is discussed.

Adolescent↗
PubMed1985

The activity of glutaraldehyde against Clostridium difficile.

The sporicidal activity of 2% glutaraldehyde against Bacillus subtilis var. globigii and Bacillus stearothermophilus was compared with that against Clostridium difficile. The aerobic species, normally chosen for test purposes, survived for 2 h but Cl. difficile was killed in under 10 min. In view of the impractical and lengthy immersions required to satisfy standard tests using non-pathogenic spores, a less stringent standard would probably be more appropriate.

Aldehydes↗
PubMed1984

Effects of temperature on the frequency of sister chromatid exchanges (SCEs) in peripheral blood lymphocytes of man and muntjac.

The incidence of sister chromatid exchanges (SCEs) and cell proliferation kinetics have been studied in peripheral blood lymphocytes of man and muntjac grown at 33 to 44 degrees C to gain insight into SCE formation. The frequency of SCEs increased as a function of growth temperature. At a given temperature, however, the frequency of SCEs varied with the sampling times; the early sampled cells showed fewer SCEs than did those harvested late. At 33 degrees C the frequency of SCEs was lowest and there was a marked delay in cell-cycle progression. The number of SCEs was maximum at 40 degrees C in human and 42 degrees C in muntjac. Cell proliferation was markedly affected at higher temperature and 44 degrees C was found to be intolerable for lymphocytes of both the species. It is proposed that certain temperature-dependent enzyme(s) associated with DNA replication kinetics may be involved in the formation of SCEs.

Animals↗
PubMed1984

The effect of storage of blood on the yield of X-ray-induced chromosome aberrations and spontaneous sister chromatid exchanges.

Heparinized whole blood of man and muntjac (Indian barking deer) was stored at 5, 22 and 37 degrees C for varying durations up to 168 hours and then exposed to 2.0 or 3.0 Gy of X-rays. The yield of dicentrics and other aberrations scored in first post-irradiation metaphases from lymphocytes of both man and muntjac did not vary significantly. However, a marked increase in the proportion of first division metaphases at a given sampling time due to delay in cell cycle progression was noticed in lymphocyte cultures set up from stored blood. There was a relatively higher proportion of first division metaphases in cultures of blood stored at the frequency of spontaneous SCEs was observed in lymphocyte cultures set up from stored and fresh blood.

Animals↗
PubMed1984

Serotyping of Acinetobacter calcoaceticus.

Serotyping of Acinetobacter calcoaceticus by direct immunofluorescence and a capsule swelling reaction is described. One hundred isolates, including 12 from an outbreak in a neonatal department, were studied. Ninety five per cent of the isolates were typable by immunofluorescence and could be divided into 30 separate types, but 42.1% of typable strains, including 11 from the outbreak, were of one type. Typing results by the capsular swelling reaction generally followed those of immunofluorescence methods.

Acinetobacter↗
PubMed1983

Reduced frequency of baseline sister chromatid exchanges in lymphocytes grown in antibiotics and serum-excluded culture medium.

Peripheral venous blood from man, muntjac, and cattle were grown in medium (1) containing different serum (human AB+/FCS/autologous), (2) without serum or antibiotics (penicillin and streptomycin), or (3) without both serum and antibiotics to investigate to what extent certain essential culture components used in in vitro mammalian cell cultures affect the incidence of spontaneous sister chromatid exchanges (SCEs). The observation that exclusion of only serum from culture medium enhanced the frequency of SCEs whereas exclusion of both serum and antibiotics, which influence the cell cycle kinetics to a great extent, exhibited the lowest frequency of SCEs reported so far for lymphocyte cultures, indicates that the frequency of so-called spontaneous SCEs usually observed in normal lymphocyte cultures grown in medium supplemented with serum and antibiotics is in fact an elevated frequency.

Animals↗
PubMed1983

Influence of age on the frequency of sister-chromatid exchanges and X-ray-induced chromosome aberrations in muntjac.

The BrdU-differential staining technique was used in a study of the frequency of sister-chromatid exchanges (SCEs) and X-ray-induced chromosome aberrations in peripheral blood lymphocytes of the same individual muntjacs. Blood was collected periodically from immediately after birth (1 day old) to the adult stage (1 year). The results showed that both the frequency of base-line SCEs and induced chromosome aberrations changed as a function of age. At a young age, the frequency of SCEs was significantly low, whereas a high frequency of chromosome aberrations was observed. But with increase in age of the individuals, an enhanced frequency of SCEs and a decreased frequency of induced chromosome aberrations were observed; and as the age advanced further, the frequencies of both SCEs and chromosomal aberrations came to a steady level.

Aging↗
PubMed1983

Ozone killing action against bacterial and fungal species; microbiological testing of a domestic ozone generator.

The action of ozone generated from a small domestic device was examined with a view to using it in clinical isolation units accommodating immunosuppressed patients. Over a six-hour period in an average size room the device did not generate sufficient ozone to suppress bacterial and fungal growth. A useful bactericidal action, against a variety of human pathogens was achieved with ozone concentrations between 0.3 to 0.9 ppm. Bactericidal ozone concentrations are close to the limit permitted for human exposure however and further experiments are indicated.

Bacteria↗
PubMed1981

Enhanced frequency of chromosome aberrations in lymphocytes of male compared with female muntjacs after X-ray irradiation in vitro.

Recently, there has been considerable interest in the study of radiation-induced dicentrics and other chromosome aberrations in phytohaemagglutinin (PHA)-stimulated blood lymphocytes of various mammals, including man, with the aim of establishing a proper biological dosimetry for the assessment of genetic radiation hazards in human. These studies have revealed that the radiosensitivity of lymphocytes differs between species and even between individuals of the same species, but the cause(s) of these variations still remains unclear. The life-shortening response to whole-body X-ray irradiation is influenced by both age and sex of the individuals, but although age has been shown to have effects on chromosome aberration yields, in vitro, the influence of sex on the sensitivity of lymphocyte chromosomes to radiation-induced damage has not been reported. It is generally thought that sex does not influence the aberration yield within the limitation of measurements used in such studies. However, we report here a study of X-ray induced chromosome aberration in lymphocytes of Indian muntjac, in which the yield of dicentrics was found to be consistently greater in male than in female lymphocytes.

Animals↗