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Biomedical subjects

R K Aggarwal

Publications and source records attributed to R K Aggarwal.

11 recordsLinked to original sources
PubMed1992

Isolation of high-molecular-weight DNA from small samples of blood having nucleated erythrocytes, collected, transported, and stored at room temperature.

Blood samples collected in the field for isolating DNA suitable for molecular analysis need special care in their storage and handling. In this article, we describe a simple method for the isolation of good-quality high-molecular-weight DNA that does not require low temperature conditions during collection, storage, and/or transportation of blood samples. This method involves smearing small aliquots of blood onto clean slides and air drying them at room temperature. The slides with blood smears can then be transported or stored at room temperature and still serve as a very good source of high-molecular-weight DNA. Genomic DNA from these samples can be extracted by organic phase separation (phenol-chloroform extraction) after lysis. The DNA thus obtained is of high quality and yields DNA fingerprints qualitatively similar to those prepared from corresponding control DNA isolated from frozen blood samples. Needing minimal facilities at field sites, the method is very convenient for conducting RFLP analysis of wild/field populations for demographic, behavioral, and ecologic studies.

Alligators and Crocodiles↗
PubMed1992

Removal of scleral explant elements: a 10-year retrospective study.

There are several studies in the American literature on the incidence and causes of retinal redetachment following removal of explants. This is, to our knowledge, the first such study from Britain and differs in its findings from the American experience. The reason for removal of explants, the time of removal after initial detachment surgery and the consequences of removal were reviewed for the 10-year period from 1980 to 1990. During this period 1898 retinal detachment operations were performed at this centre, with an explant removal rate of 3.2% (61 eyes). Extrusion of the element was the cause in 74%. Of these 8% subsequently suffered a redetachment. In two eyes no retinal break was identified at initial surgery. Both of these suffered a redetachment following removal of the explant. Contrary to previous reports, redetachment was not related to short periods of explant or to infection of the explant. This study suggests that explant removal is a safe procedure. However, there is a significant risk of redetachment after explant removal if no breaks are identified at the time of initial surgery.

Adolescent↗
PubMed1992

Contrast sensitivity and glare in cataract using the Pelli-Robson chart.

There is a need for a convenient, clinically applicable test of glare disability which can be used in the preoperative evaluation of patients with cataract. In this study, contrast sensitivity (using the Pelli-Robson letter chart), near vision, and visual acuity were compared, with and without the introduction of a glare source in 70 patients with cataract, 15 with intraocular lenses, and 19 controls. A disposable pen torch was shone at the pupillary margin to induce glare. Contrast sensitivity demonstrated the most marked reduction during glare testing. Cortical cataracts were most affected followed by posterior subcapsular opacities. The glare disability was significantly less in pseudophakic patients and was absent from patients with non-cataractous phakic eyes. Glare testing with a disposable pen torch and a Pelli-Robson contrast sensitivity letter chart provides a rapid test of glare disability which can be easily incorporated into the clinical appraisal of patients with cataract.

Aged↗
PubMed1992

Relative performance of Organon kit in comparison to Du Pont for confirmatory serological testing of HIV infection by western blot test in sera from blood donors.

A total of 32 specimens with different categories of reactivity by Du Pont Western Blot kit comprising of specimens showing full spectrum of HIV-I antigen specific bands, 19 specimens showing total absence of bands and four specimens showing non-specific bands (without any interpretative importance) were subjected to Western Blot testing by Organon test. Of the nine specimens showing full spectrum of bands by Du Pont the correlation with Organon kit was 100 per cent based on WHO criteria. Four specimens with non-specific indeterminate band pattern by Du Pont failed to show any band in Organon kit, indicating that latter to be more specific.

AIDS Serodiagnosis↗
PubMed1991

The quantitation of rabies-specific antibodies. I. Modified counter immunoelectrophoresis. A rapid and sensitive method.

Modified counter immunoelectrophoresis was standardized with respect to dilution of tissue culture antigen and indicator serum, the incubation time for neutralization and the effect of an electric current. The technique was found to be sensitive enough to detect a minimum level of antibodies (0.5 IU/ml) by using a 16 mA current per slide for 2 h, indicator serum of 15 IU/ml and the use of an antigen at a concentration of 1:35. Above all, the incubation period did not affect the neutralization of the virus. The test was also applied to the detection of rabies-specific antibody levels in 73 human sera. The test was found to be simple, quick and economical for titration of rabies antibodies.

Antibodies, Viral↗
PubMed1991

The quantitation of rabies-specific antibodies. II. Factors affecting the sensitivity of the haemagglutination inhibition test.

Various factors affecting the HAI test for the quantitation of rabies-specific antibodies have been evaluated with a view to obtaining maximum sensitivity and reproducibility in tests using tissue culture antigens prepared in vero cells and concentrated by dialysis. Goose erythrocytes treated with proteolytic enzyme bromelian at a concentration of 0.025% were much more susceptible to HA than those that were untreated or erythrocytes treated with neuraminidase. In addition, other parameters like the use of a phosphate buffered saline (PBS) as a diluent at pH 6.2, incubation at 0-4 degrees C for 1.5-3 h were found to be most critical for achieving maximum HA activity. To remove non-specific inhibitors, serum samples were treated with aerosil, acetone in combination or alone. Of the 73 serum samples tested, removal of non-specific inhibitors by aerosil alone occurred in up to 54.79% of the samples, whereas using acetone-aerosil treatment followed by adsorption with goose erythrocytes, the inhibitors were removed in 98.67% of the samples to a level that was undetectable at the 1:4 starting dilution in the HAI test.

Acetone↗
PubMed1991

The quantitation of rabies-specific antibodies. III. A comparative evaluation of modified counter immunoelectrophoresis, haemagglutination inhibition and serum neutralization titres of human sera.

The rabies-specific antibodies of 73 serum samples from vaccinated humans were determined by the modified counter immunoelectrophoresis (MCIE), and the haemagglutination inhibition test (HAI) by using the conventional serum neutralization test (SN) as a yard-stick. Both MCIE and HAI were found to be sensitive and specific for the estimation of rabies antibodies. In general, the unitages obtained by the MCIE and SN showed statistically insignificant differences (P greater than 0.05) and the correlation coefficient between the two methods was 0.697 (P less than 0.05). Although the unitage of the sera detected by HAI tests was lower by a factor of 0.155 from the unitage of SN tests, there was statistically insignificant differences between the two techniques (P greater than 0.05) with a correlation coefficient of 0.556 (P less than 0.05).

Antibodies, Viral↗
PubMed1977

A multi-spectral approach for scene analysis of cervical cytology smears.

A multi-spectral approach for the scene analysis of cervical cytology smears, using multiple images of a scene digitized through suitably chosen color filters matched to the Papanicolaou stain, has been proposed here. This technique involves clustering of two-dimensional data for extracting cytoplasm of the epithelial cells. Its performance on an experimental data set of 233 scenes involving more than 10 types of normal and malignant epithelial cells has been compared with density and gradient thresholding techniques. This resulted in an approximate 83% rate of success compared to approximately 40% for the rest of the other techniques.

Cell Nucleus↗
PubMed1976

Image processing for automated erythrocyte classification.

Digital image processing and pattern recognition techniques were applied to determine the feasibility of a natural n-space subgrouping of normal and abnormal peripheral blood erythrocytes into well separated categories. The data consisted of 325 digitized red cells from 11 different cell classes. The analysis resulted in five features: (a) size, (b) roundness, (c) spicularity, (d) eccentricity and (e) central gray level distribution. These features separated the data into six distinct condensed subgroups of red cells. Each subgroup consisted of morphologically similar cells: (a) macrocytes, (b) normocytes, (c) schistocytes, acanthocytes and burr cells, (d) microcytes and spherocytes, (e) elliptocytes, sickle cells and pencil forms and (f) target cells. The concept of a quantitative "red cell differential" was introduced, utilizing these subgroup definitions to establish subpopulations of red cells, with quantifiable indices for the diagnosis of anemia, at the specimen level.

Autoanalysis↗