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Biomedical subjects

A Sundaram

Publications and source records attributed to A Sundaram.

14 recordsLinked to original sources
PubMed2004

Multidrug resistant proteins: P-glycoprotein and lung resistance protein expression in retinoblastoma.

BACKGROUND/AIM: Retinoblastoma is the commonest primary intraocular tumour in children. Chemotherapy now plays a big part in the treatment of these tumours. There is not much information about the role of the multidrug resistance proteins (MDR)-P-glycoprotein (P-gp) and vault protein lung resistance protein (LRP)-in retinoblastoma. The authors investigated the expression of P-gp and LRP in retinoblastoma and correlated them clinicopathologically. METHODS: Among 60 retinoblastomas, 40 tumours were not subjected to preoperative or postoperative chemotherapy and 20 tumours were subjected to postoperative chemotherapy. In this cohort 27 tumours had no invasion and 33 tumours had invasion of choroid, optic nerve, and orbit. P-gp and LRP expression were studied by immunohistochemistry. Immunoanalysis was done semiquantitatively. RESULTS: Among the 60 tumours P-gp was expressed in 23 (38%) tumours and LRP was expressed in 35 (58%). P-gp was expressed in 11/27 (40%) tumours with no invasion and in 12/33 (36%) tumours with invasion. LRP was expressed in 15/27 (55%) tumours with no invasion and in 20/33 (60%) tumours with invasion. Both P-gp and LRP were negative in three tumours with invasion, which had later developed bone marrow metastasis. There was no correlation between P-gp and LRP expression with invasion, differentiation and laterality of the tumours and response to treatment. CONCLUSION: Retinoblastoma expresses P-gp and LRP intrinsically before chemotherapy and none of these proteins predicted the response to chemotherapy. Thus, further studies are needed to understand the significance of the expression of the P-gp and LRP proteins in retinoblastoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Comparative analysis of monoclonal antibody based enzyme immunoassay, modified genome electrophoresis & electron microscopy procedures for rotavirus diagnosis from faecal specimens.

BACKGROUND & OBJECTIVES: Reliable and rapid diagnosis of rotavirus infection is necessary for patient management. Several newly introduced commercial enzyme immunoassays (ELISAs) have been evaluated using direct electron microscopy (DEM) with or without direct ultracentrifugation as the standard reference method, and have shown varying results. METHODS: In the present study we compared the diagnostic efficacy of the three methods viz., monoclonal antibody (MAb) ELISA, modified polyacrylamide gel electrophoresis (PAGE) and DEM without ultracentrifugation in the detection of rotaviruses from 211 stool specimens. The data were analysed by two latent class model (2LC) in the absence of a gold standard reference method. RESULTS: Rotavirus was detected in 42 specimens by MAb-ELISA; in 40 specimens by PAGE and in 33 specimens by DEM. The estimates of sensitivities and specificities of the three methods were analysed by 2LC method. The analysis revealed no significant variation among the three methods. However, DEM was found with a comparatively lesser sensitivity over the other two methods. INTERPRETATION & CONCLUSIONS: Though DEM was found to be relatively less sensitive than the other two methods, the differences were not significant, and all the three methods were highly specific. Moreover, DEM has the additional advantage of detecting non-group A and other gastroenteritis viruses. The findings suggest the use of highly sensitive and specific MAb-ELISA and PAGE in parallel to detect group A, non-group A and atypical rotavirus infection in the population.

Antibodies, Monoclonal↗
PubMed1996

Categorization and modeling of information work for H-journal design.

This paper reports on a doctoral research project that examined the work of reference librarians in the health sciences domain. Categories of information work are derived and used to build Hyper-MedLib, a proof-of-concept h-journal. Findings from this study may be used in the design of electronic documents and information systems for the practice environments.

Hypermedia↗
PubMed1993

An unnatural biopolymer.

A highly efficient method has been developed for the solid-phase synthesis of an "unnatural biopolymer" consisting of chiral aminocarbonate monomers linked via a carbamate backbone. Oligocarbamates were synthesized from N-protected p-nitrophenyl carbonate monomers, substituted with a variety of side chains, with greater than 99 percent overall coupling efficiencies per step. A spatially defined library of oligocarbamates was generated by using photochemical methods and screened for binding affinity to a monoclonal antibody. A number of high-affinity ligands were then synthesized and analyzed in solution with respect to their inhibition concentration values, water/octanol partitioning coefficients, and proteolytic stability. These and other unnatural polymers may provide new frameworks for drug development and for testing theories of protein and peptide folding and structure.

Amino Acid Sequence↗
PubMed1992

Effect of bed time intermediate acting insulin in NIDDM subjects refractory to a combination of sulphonylureas and biguanides.

The effect of a single dose of intermediate acting (Lente) insulin given subcutaneously at 9.00 P.M. in 22 NIDDM subjects refractory to a combination of Sulphonylureas and Biguanides was analysed. Euglycemia was achieved and maintained during the study period of three months with a mean insulin requirement of 14.22 +/- 5.98 units/day. Plasma FFA, Total cholesterol, triglyceride and VLDL-cholesterol also showed significant reduction. The level of FFA modulates hepatic glucose production, which in turn correlates positively with the fasting blood glucose. The therapeutic modality of bed time Lente Insulin based on physiological principles is an effective way of achieving glycemic control in NIDDM subjects who have become non-responsive to oral hypoglycemic agents.

Biguanides↗
PubMed1992

Subcutaneous insulin pulse therapy.

Subcutaneous Insulin Pulse Therapy (SIPT) consists of administration of small doses of regular insulin hourly or two hourly in the subcutaneous tissue of anterior abdominal wall through a scalp vein needle. Fifteen Non-Insulin Dependent Diabetes Mellitus (NIDDM) subjects, 8 males and 7 females with mean ages 58 +/- 8.7 years and mean duration of diabetes 11.7 +/- 9.1 years and mean BMI 25.2 +/- 5.64 were admitted for elective surgery. Glycemic control was attempted preoperatively with multiple pre-meal doses of Actrapid MC with a single injection of Monotard MC at bed time. The mean fasting plasma glucose in the 15 subjects with this insulin regimen was 321.28 +/- 69.32 mgm% and the insulin requirement per day was 106.87 +/- 35.77 units. The subjects were put on SIPT for 48 to 72 hours. During SIPT the mean fasting plasma glucose dropped to 123.2 +/- 74.11 mgm% and this marked decline in fasting plasma glucose value was statistically significant (P < .05). The insulin requirement during SIPT was 96.42 +/- 31.36 units, similar to the previous regimen (NS). The subjects were switched back to conventional insulin therapy after SIPT during which period the mean fasting plasma glucose was 125.82 +/- 34.50 mgm% and this value was again significantly lower than the pre SIPT fasting plasma glucose value (P < .05). Insulin requirement during conventional insulin therapy after SIPT was reduced to 71 +/- 21.89 units/day. This dose was significantly lower than the insulin dose administered during SIPT (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1990

Keloids and diabetes in a family.

An interesting familial association of keloids with diabetes mellitus in three successive generations is reported. Keloids did not develop if the injection site was changed to the anterior abdominal wall.

Administration, Cutaneous↗
PubMed1987

Influence of adjuvants on physicochemical properties, droplet size spectra and deposit patterns: relevance in pesticide applications.

The influence of adjuvants on physicochemical properties, droplet size spectra and deposit patterns of five aqueous spray mixtures was studied under laboratory conditions, using two surfactants, Atlox 3409F and Triton X-114; two humectants, propylene glycol and glycerol; and one polymeric adjuvant, Agrisol FL-100F. For the sake of comparison, two fenitrothion formulations containing polymeric adjuvants, and water were also included in the study. Spray was applied at 25 degrees C and 75 +/- 5% relative humidity, in an enclosure using a twin fluid atomizer. Deposits were collected on Kromekote card/glass plate units. Physicochemical properties studied were: relative viscosity, surface tension, apparent viscosity-shear rate relationship, volatility, pH and conductance. The first four of these properties played significant roles on the droplet and deposit patterns on sampling units. However, the chemical nature of the adjuvants also played some role. Between the two surfactants tested, Triton X-114 provided a pseudoplastic medium, but both surfactant solutions provided similar droplet size spectra and deposit patterns. Between the two humectants, glycerol proved to be more advantageous than propylene glycol. The polymeric adjuvant provided droplet sizes similar to those of the two surfactants, although the recovery of the applied spray volume was higher. Among the two fenitrothion formulations, the one containing lower amounts of polymeric adjuvants showed some advantages, although deposits on the actual biological target should be examined before any definite conclusions can be drawn on the optimum adjuvant concentrations in end-use formulations.

Chemical Phenomena↗
PubMed1987

Influence of surfactants and polymeric adjuvants on physicochemical properties, droplet size spectra and deposition of fenitrothion and Bacillus thuringiensis formulations under laboratory conditions.

The effect of two surfactants and two polymeric adjuvants on droplet size spectra and deposition patterns of nine spray formulations was investigated following atomization in a laboratory chamber using a spinning disc atomizer that can produce a narrow droplet size spectrum. Spray droplets were sampled using Kromekote cards and deposit recoveries were examined on glass plates. Physicochemical properties studied were: viscosity-shear rate relationship, surface tension, volatility, pH, conductance, electrophoretic mobility and zeta potential. Formulations containing low surfactant concentrations provided Newtonian liquids with low viscosities. These liquids atomized into small droplets and provided low recoveries of spray deposits on sampling units. However, formulations containing polymeric adjuvants, and a high concentration of a non-ionic surfactant provided pseudoplastic liquids with high viscosities. These formulations resulted in large droplets with high recoveries of spray deposits on sampling units. Among the physicochemical properties studied, viscosity, surface tension, volatility and electrophoretic mobility, played important roles on liquid atomization and droplet deposition.

Aerosols↗
PubMed1985

Influence of formulation properties on droplet spectra and soil residues of aminocarb aerial sprays in conifer forests.

The influence of formulation properties on spray droplet spectra and soil residues was studied in conifer forests in New Brunswick following aerial application of two oil-based aminocarb formulations of variable viscosities and volatilities. For a given volume rate of application, the formulation of low viscosity and high volatility provided a spectrum of small droplets and a low volume deposit on ground cards. For the same volume rate, the nonvolatile formulation of high viscosity provided a spectrum of larger droplets and consequently a higher volume deposit. Both formulations provided low soil residues, although those obtained with the nonvolatile formulation were much higher and persisted for much longer periods than those obtained with the volatile formulation. However, with both formulations the soil residues decayed to undetectable levels (less than 3 ng/g) within 5 days after spraying, indicating that none of the formulations caused any undue persistence of aminocarb in forest soils.

Carbamates↗
PubMed1980

Subchronic toxicity of photomirex in the female rat: results of 28- and 90-day feeding studies.

Photomirex (8-monohydromirex) was administered to female Sprague-Dawley rats at dietary levels of 0.2, 1.0, 5.0, 25.0 and 125 ppm. Food intake and body weight gain were significantly depressed at the 125 ppm level in the 28- but not in the 90-day study. Significant alterations were observed in some hematological and biochemical parameters at the highest dietary level in the 90-day study. Photomirex residues accumulated in a dose-dependent manner in perirenal fat, liver, brain, kidney, and spleen. Dose-dependent histotoxic effects were observed in liver and thyroid at and above 1 ppm; hepatomegaly was observed at 25.0 and 125 ppm. These results indicate that photomirex was approximately five times more toxic than mirex in terms of liver histology. When these results are compared with those observed in an earlier study in the male rat, it is evident that the female is less susceptible to photomirex than the male.

Adipose Tissue↗
PubMed1977

Retention and tissue distribution of 210Pb (NO3)2 administered orally to infant and adult monkeys.

The retention and tissue distribution of 210Pb were studied in 10-day-old, 150-day-old, and adult monkeys. Lead-210 nitrate was administered to the monkeys by gavage after a 12 hr fast and 210Pb excreted in urine and feces was monitored for 96 hr. All monkeys were necropsied 96 hr after dosing and the 210Pb concentrations of various tissues was determined. The data demonstrated that infant monkeys retained 64.5 and 69.8% of the orally administered 210Pb at 10 and 150 days of age, respectively, while adult monkeys retained 3.2% of the 210Pb dose. Blood 210Pb levels 96 hr after dosing did not vary significantly between age groups. Of the 210Pb contained in blood, 98-99% was found in blood cells and 1-2% in blood plasma; 5-8% of the Pb in blood cells was bound to blood cell membranes. None of these parameters varied significantly with age. The percentage of the lead dose excreted in urine did not vary significantly between age groups. Analysis of tissues for 210Pb revealed that both the tissue Pb concentrations and tissue Pb:blood Pb ratios were significantly higher in the bone structure of infants than adults. Brain Pb:blood Pb ratios were significantly greater in 10-day-old infants than 150-day-old infants or adults.

Administration, Oral↗