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Biomedical subjects

M Subramanian

Publications and source records attributed to M Subramanian.

At least 37 records · Page 2Linked to original sources
PubMed1994

The influence of operational factors in the profile of monolesional leprosy cases in south India.

A comparison of the profile of monolesional cases among new PB cases detected in a Government Leprosy Control Unit (GLCU) and the field area of a Central Leprosy Teaching and Research Institute (CLTRI), both located in South India, demonstrates that the proportion of monolesional cases among new cases detected between 1987 and 1991 was higher in children than adults, higher in females than males (only in the CLTRI)--over 95% were the tuberculoid type. A significantly increasing trend in this proportion could be seen in the GLCU but not in the CLTRI; an explanation of this is based on the difference in operational aspects in case detection methodology adopted by the 2 areas--e.g. intersurvey interval and mode of case detection. Such studies, focusing on single skin lesions, help us in understanding the role of various possible operational factors in influencing the behaviour of the disease.

Adult↗
PubMed1994

Ofloxacin-containing combined drug regimens in the treatment of lepromatous leprosy.

A total of 26 clinically diagnosed adult patients, with active untreated lepromatous leprosy, with a Bacteriological Index of 4+ or more, were admitted to the hospital of the Central Leprosy Teaching and Research institute, Chengalpattu, India, between 1989 and 1991. After prescribed investigations, the patients were randomly allocated in groups of 3 to 3 treatment regimens, namely: 1, clofazimine 50 mg daily and 300 mg once in 4 weeks + dapsone 100 mg daily (AA); 2, (AA)+ofloxacin 400 mg daily (BB); and 3, (AA)+ofloxacin 800 mg daily (CC). The drugs were administered for 56 days continuously under supervision. Sequential biopsy results on day 0, 7, 14, 28 and 56 in normal mouse footpad revealed no growth by day 28 and 56 in all patients treated with CC and BB regimens, respectively. Calculation of the proportion of viable Mycobacterium leprae through analysis of median infectious dose (ID50) showed significant differences on day 7 in the percentage of kill between the ofloxacin-containing regimens and the other. Moderate to marked clinical improvement has been observed in a significantly higher proportion of patients treated with ofloxacin-containing regimens. All the 3 regimens were well tolerated. No severe complications or side-effects to the drugs were noticed with any of the regimens that required any suspension of treatment or the administration of steroids. Addition of ofloxacin to the standard WHO recommended MDT regimen for multibacillary patients may reduce the present duration of therapy. Ofloxacin may also be considered as an alternative drug in rifampicin-resistant cases or where rifampicin is contraindicated.

Adult↗
PubMed1994

Prevalence of HIV infection and high-risk characteristics among leprosy patients of south India; a case-control study.

With the observation of the occurrence of the human immunodeficiency virus (HIV) infection among leprosy patients in our pilot study carried out in Tamil Nadu, South India, a case-control study was planned to explore whether HIV infection is a risk factor for leprosy and to understand the characteristics of HIV infection and high-risk behaviors among leprosy patients. We screened 556 patients and 1004 nonleprosy controls (matching 502 cases for age, sex and area of residence) for HIV-1 and HIV-2 antibodies. They also were interviewed for personal information on history of blood transfusion, intravenous drug abuse, high-risk sexual behavior, and sexually transmitted diseases. Of the 1019 total cases screened (of both pilot and extended studies), 5 were found to be position for HIV antibodies (HIV-1 = 4, HIV-2 = 1); of the 1019 nonleprosy controls, 6 were positive for HIV-1 antibodies. An analysis by odds ratio revealed no association between leprosy and HIV infection (OR = 0.824, 95% CI = 0.201-3.593). A strong association was found only between high-risk behavior and HIV infection (OR = 5.186, 95% CI = 1.717-15.667). However, unmarried, unmarried after 30 years of age, exposure to spouses of the leprosy patients, and a history of surgery were all observed to be significantly more common among leprosy patients than the controls.

Adolescent↗
PubMed1993

Gestation confers temporary resistance to peroxidation in the maternal rat brain.

Lipid peroxidation, as assessed by the formation of thiobarbituric acid substances on incubation with ascorbate-Fe2+, NADPH-ADP-Fe3+ and cumene hydroperoxide in brain homogenate and mitochondria, was significantly decreased during gestation and restored to respective control levels post partum. The decrease observed with the brain homogenate on Day 10 of pregnancy was 42% with ascorbate-Fe2+ and 70% with NADPH-ADP-Fe3+. This temporary decrease in peroxidation potential seems to be due to lesser availability of substrate in the form of unsaturated fatty acids besides increase in the cholesterol:phospholipid ratio and glutathione. Progesterone, the gestational steroid elaborated during pregnancy, inhibited lipid peroxidation in brain mitochondria in a dose-dependent manner. The observed temporary decrease in peroxidation potential may be a special adaptation to protect membranes in the brain against oxidant stress during pregnancy.

Adenosine Diphosphate↗
PubMed1993

Prevention of singlet oxygen-induced DNA damage by lipoate.

Among the several biologically and pharmacologically active sulfur compounds examined, only lipoic acid and dihydrolipoic acid provided protection to plasmid DNA against singlet molecular oxygen (1O2). 1O2 was generated in phosphate buffer by the thermal dissociation of the endoperoxide of 3,3'-(1,4-naphthylidene) dipropionate (NDPO2). The protecting effect of lipoic acid was time- and pH-dependent and significant protection was seen even at 50 microM. The antioxidant effect was adversely affected by temperatures above 45 degrees C. Superoxide dismutase and catalase marginally enhanced this effect. Metal chelation with EDTA decreased the protection by lipoate, indicating that metal ions may be involved. The protective effect was diminished when the disulfide was added after single-strand breaks were induced by 1O2. The formation of 8-oxoguanosine from guanosine upon exposure to NDPO2 was not altered by lipoate.

Catalase↗
PubMed1993

Serological response of leprosy patients to Mycobacterium leprae specific and mycobacteria specific antigens: possibility of using these assays in combinations.

The serological response of 147 leprosy patients to 3 mycobacterial antigens, PGL-I, 35 kDa (Mycobacterium leprae-specific) and LAM (which is a common mycobacterial antigen) were analysed. A stronger serological response was seen amongst the MB patients than the PB patients in all the assays. The 3 antibody levels correlated positively with each other in both MB and PB cases. An overlap of seropositivity was seen between anti-PGL-I and anti-LAM (p > 0.05). A progressive increase in seropositivity and a significant difference of absorbance or titre in antibody levels in all 3 assays over increasing grades of BI were seen in the MB patients (p < 0.05). A significant difference in seropositivity between untreated and treated groups of patients was observed for anti PGL-I (p < 0.05) and antiLAM (p < 0.01) antibodies. The sensitivity, specificity and efficiency of antiPGL-I (50%; 99%; 70%), antiLAM (43%; 95%; 64%) and anti35 kDa (66%; 100%; 80%) assays taken individually were less than that of combinations of antiPGL-I/anti-35 kDa (74%; 99%; 84%) or antiPGL-I/anti-35 kDa/antiLAM (80%; 94%; 86%). The difference in the efficiency of both sets of combination of assays were not statistically significant (p > 0.05).

Antibodies, Bacterial↗
PubMed1991

Seroepidemiological study of leprosy in a highly endemic population of south India based on an ELISA using synthetic PGL-I.

As part of a continuing longitudinal immuno-epidemiological study, blood samples were collected by finger prick from 4243 individuals living in a highly endemic area for leprosy in South India. The samples were tested for IgM antibodies against phenolic glycolipid-I using an ELISA. Seropositivity defined as optical density greater than or equal to 0.2000 was marginally higher in the age group 10-30 years and in females. There was no evidence for a higher level in contacts than in non-contacts. The future prospect for the large scale use of this ELISA in high-endemic populations in special epidemiological investigations or routine control programs as a serological tool to detect leprosy infection appears questionable.

Adolescent↗
PubMed1990

Oxidative phosphorylation in mouse liver mitochondria during weaning.

Oxidative energy metabolism in mouse liver mitochondria was examined during weaning using different substrates. During the post-natal development, from suckling to weanling stage, the respiration rates showed a temporary decrease. These altered levels recovered in the adults. Respiration rates with the three substrates studied namely, glutamate, beta-hydroxybutyrate and succinate showed the same pattern. However, the levels of primary dehydrogenase as well as that of basal adenosine triphosphatase were not significantly altered during weaning. The content of cytochromes aa3 and b significantly decreased during this period. The results indicate that cytochrome aa3 may be of primary importance in the restoration of full respiratory function in mitochondria after the weaning period.

3-Hydroxybutyric Acid↗
PubMed1990

Maternal age does not affect tetrahydrocannabinol's in utero actions in rats.

The potential contribution of maternal age to tetrahydrocannabinol's (THC) in utero effects in rats was studied. Pregnant animals were intubated with 25, 10 or 0 mg/kg of THC from gestation day six to parturition. Animals in the 10 and 0 mg/kg groups were pair fed to those given the 25 mg/kg dose. Each series of doses was administered to females three, four or six months of age. THC lowered maternal weight gain and weights of offspring at birth and at 21 days of age, but did not affect litter size, spontaneous alternation or passive avoidance learning in offspring. Increased maternal age was associated with smaller litter size and lower birth weight and weight at 21 days, but did not interact significantly with THC.

Animals↗
PubMed1990

Inhibition of the RNA polymerase of vesicular stomatitis virus by ppp5'A2'p5'A and related compounds.

The diadenylate triphosphates ppp5'A2'p5'A and ppp5'A3'p5'A were found to inhibit the purified RNA polymerase ('nucleocapsid') complex from vesicular stomatitis virus (VSV). The corresponding diadenylate monophosphate p5'A2'p5'A did not inhibit, nor did the triadenylate triphosphate ppp5'A2'p5'A2'p5'A; the diadenylate diphosphate pp5'A2'p5'A had intermediate inhibitory activity. Increasing the concentration of ATP, GTP or CTP in the reaction mixture decreased inhibition by ppp5'A2'p5'A, while UTP had minimal or no protective effect. ppp5'A2'p5'A did not protect the RNA polymerase from inactivation by N-ethylmaleimide. This suggests that the action of ppp5'A2'p5'A occurs at a site on the enzyme that is distinct from the N-ethylmaleimide-protecting, ATP-binding site characterized previously.

Adenine Nucleotides↗
PubMed1987

Effects of delta 9-tetrahydrocannabinol, phenobarbital, and their combination on pregnancy and offspring in rats.

delta 9-THC, sodium phenobarbital, or a combination of these drugs, were administered to pregnant mice on gestation days 6 to parturition. Levels of delta 9-THC in blood approximated levels attained in humans after smoking one to two marijuana cigarettes. Blood cannabinoid levels in mice were not significantly elevated by concurrent drug administration. Both drugs significantly reduced litter size and weight per pup at birth, but the combination of these drugs did not affect these outcomes to a significantly greater degree than either drug by itself. Phenobarbital but not delta 9-THC increased resorption rate.

Animals↗
PubMed1984

Interaction of cationic detergents, cetyl- and dodecyl-trimethylammonium bromides, with lysozyme.

Binding of lysozyme with cetyltrimethylammonium bromide (CTAB) and dodecyl-trimethylammonium bromide (DTAB) at various detergent concentrations and pH was studied at 25 degrees C by equilibrium dialysis technique. In the case of CTAB, binding isotherms at pH 5.0, 7.0, and 9.0 show cooperative binding at all the concentrations of the detergent and the binding ratios increase with pH. Cooperative binding is also shown by DTAB at all the concentrations and pH, but the binding ratios are lower compared to CTAB. The Gibb's free energy change calculated on the basis of Wyman's binding potential concept increases with pH, indicating increased binding strength of CTAB at higher pH. The UV difference spectra of CTAB and DTAB with lysozyme and its model compounds such as L-Trp, L-Tyr X HCI and L-Phe show two peaks at 297 nm and 250 nm at pH 9.0 indicating the possible involvement of tryptophans as the binding sites along with the carboxylate anion or the phenolic group of a tyrosine on lysozyme. The effect of higher ionic strength on the binding of CTAB with lysozyme at pH 9.0 is evidenced by lower binding ratios and decreased intensities of the UV difference bands, thus indicating the involvement of electrostatic interactions. However, the hydrophobic interactions between the detergents and the aromatic amino acid residues in lysozyme contribute more to the binding strength. The binding of these cationic detergents by lysozyme induces conformational changes in the enzyme. They are followed by the circular dichroism (CD) technique which shows a decrease in the aromatic bands in the 320-250 nm region.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Interaction of lysozyme with dyes. II. Binding of bromophenol blue.

The binding of lysozyme with bromophenol blue (BPB) at various dye concentrations and pH was carried out at 25 degrees C by equilibrium dialysis, ultraviolet (UV) difference and circular dichroism (CD) spectral techniques. Binding isotherms at pH 5.0 show non-cooperative binding at low dye concentrations, which change over to cooperative binding at higher concentrations indicating biphasic nature. However, binding isotherms at pH 7.0 and 9.0 show cooperative binding only, at all concentrations of the dye. The number of available binding sites decreases with the increase of pH. Gibbs free energy change, calculated on the basis of Wyman's binding potential concept, decreases with the increase of pH. Binding isotherms at pH 5.0 obtained at a lower temperature of 8 degrees C, also indicate the biphasic nature similar to those observed at 25 degrees C, but with a slight decreased strength of binding. The UV difference spectra of the complex do not show any distinct peaks in the 285 to 297 nm region eliminating any possible interaction of BPB with tryptophan and tyrosine residues of the lysozyme molecule. The CD spectra of lysozyme-BPB complex show a decrease in ellipticities with reference to native lysozyme in the near UV and far UV regions. This indicates that the lysozyme-BPB complex has a lower helical content probably due to the conformational changes induced into the native enzyme. The appearance of new positive peaks at 315 nm in the near UV region and at 592 nm in the visible region of the CD spectra may be due to the induced asymmetry into the BPB molecule as a result of its binding to a cationic residue (probably a lysine residue) of lysozyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1975

Socio-economic and environmental factors and human health example of cholera El Tor in Manila.

The environmental health factors relevant to the occurrence of cholera in an urban milieu (Manila) have been studied. Cholera has been found to be a disease significantly more prevalent in the areas with lowest environmental condition. Association have been found between the disease incidence and several socioeconomic variables: population density, water and sewer connections each per 1000 population and squatter/slum dweller density. The correlation between cholera incidence and population density was found to be statistically significant at 5% level. A multiple regression analysis showed that the variations in cholera incidence were explained to the extent of 53.23% by the three variables-population density, water and sewer connections. In a check, using data for several years, positive correlations were found between incidence rates and the number of persons per sanitary facility, overcrowding, and density per square kilometer. The association between cholera and the low levels of socioeconomic conditions has been examined in a detailed study of a sample of 711 patients during the cholera season 1971-72. The socioeconomic profile of the sample places the patients in the least affluent part of the community. - The paper points out the need for priority of urban redevelopment in areas of maximum health risk.

Cholera↗