Biomedical subjects
Publications and source records attributed to R Kumar.
This case report describes a patient with sciatica resulting from lumbar root compression by a gas-containing cyst in the extradural space. Removal of the cyst provided prompt relief. The origin and anatomic distribution of gas collections in the spine are considered based on a review of the literature.
5-(1-Hydroxy-2-haloethyl)- (4), 5-(1-methoxy-2-haloethyl)- (5) and 5-(1-hydroxy-2-methoxyethyl)uracils (6) (see Figure 2 for structures) were synthesized to investigate the effect of the C-5 substituents on cytotoxic and antiviral activity. The bromo compounds (4b and 5b) exhibited greater cytotoxic activity than the chloro or iodo analogues in the in vitro L1210 assay. Replacement of the hydroxyl substituent of 4b (bromo) and 4c (iodo) by a methoxyl substituent (5b-c), or substitution of their halogen substituents by methoxyl (providing 6) increased the potency. However, the cytotoxic activity of all the compounds was weak, the most active (6) producing a 45% decrease in cell survival at a concentration of 50 micrograms/ml, as compared with a 97% decrease when the reference standard (melphalan) was tested at 1 microgram/ml. They were inactive antiviral agents against herpes simplex virus type 1 (HSV-1) infected Vero cells at 10 micrograms/ml; in the same test, the reference standard (acyclovir) exhibited an ID50 of 0.01 micrograms/ml.
A rural cohort of 507 children, less than 3 yr of age was kept under weekly surveillance for 12 months, for morbidity due to diarrhoea. Stool specimens for rotavirus detection were obtained in 346 of the 360 diarrheal episodes occurring in 354 children and in 211 children without diarrhoeal symptoms. Rotavirus was detected by an ELISA test in 4 per cent of children with diarrhoea and 6.6 per cent of control subjects. Viral genome RNA was extracted by phenol chloroform method from all the positive samples and analysed by polyacrylamide gel electrophoresis followed by silver staining. All the strains isolated, exhibited the same electropherotype with a 'long' RNA migration pattern. This result contrasts with the genomic variability amongst rotavirus strains usually observed in different settings.
A commercial latex agglutination (LA) test was compared with ELISA and direct electron microscopy (EM) for detection of rotavirus antigen in 93 stool specimens obtained from as many children with acute gastroenteritis. Seventy one specimens (76.3%) were either positive or negative with all the three techniques, while 22 (23.7%) gave contradictory results. Only 1 sample was positive by LA test but not with ELISA or EM. The sensitivity of LA test and EM was 62.5 per cent (30 of 48) and 75 per cent (36 of 48); the corresponding specificity being 97.7 per cent (44 of 45) and 100 per cent (45 of 45) respectively. ELISA was more sensitive than the LA test and EM for detection of rotavirus antigen. LA test which is highly specific and a rapid method, may be useful in certain situations but its low sensitivity makes it unsuitable for use in routine clinical practice.
The polymerase chain reaction (PCR) technique has greatly facilitated the identification of ras oncogenes by allele-specific hybridization of the PCR-amplified DNA to radioactively labelled oligonucleotide probes. In this study, we describe a different method which employs designed mismatch primers that create diagnostic restriction fragment length polymorphisms (RFLPs). This procedure allows the identification of point mutations in the amplified DNA without the use of any radioactive probes. We apply this method to the detection of specific point mutations in the rat H- and K-ras oncogenes in carcinogen-induced tumors. We also suggest strategies for the diagnostic RFLP analysis of most point mutations in the 12th and 61st codons of human ras oncogenes. This simple method is especially suitable for analyzing minuscule amounts of tissue samples where only a fraction of cells may carry activated oncogenes.
Explore the source record for details and available documents.
Thirty cases of neonatal hyperbilirubinemia of varying etiology, severity and duration; and twenty six normal healthy newborns were subjected to various tests of cellular and humoral immunity. The results revealed a significant depression of all the parameters of cellular immunity in neonatal hyperbilirubinemia of greater than or equal to 10 mg/dl as compared to the control values. The depression of immunological profile in these newborns was seen to be more pronounced with increasing duration and severity of jaundice. A limited assessment of the humoral immunity by the B cell count and serum immunoglobulin IgG levels, however, showed no significant difference from the control.
Paroxysmal nocturnal haemoglobinuria is an uncommon condition characterised by undue susceptibility of the red cells to get lysed by the complement components. Three cases of this disorder encountered over a period of two years are presented here.
Explore the source record for details and available documents.
The duodenal juice and fecal aerobic microflora was investigated in 54 patients with persistent diarrhea (age less than or equal to 2 years). The duodenal aspirates yielded increased aerobic bacteria (greater than 10(5) organisms/ml) in 28 (51.9%) of the patients. Established enteric pathogens were isolated from the duodenal aspirates of 12 (22.2%) of the 54 patients, viz., enteroadherent Escherichia coli (EAEC) (5), enterotoxigenic E. coli (ETEC) (3), enteropathogenic E. coli (EPEC) (1), nontyphoidal Salmonella (1), and Giardia lamblia (2). The total aerobic bacterial count was greater than 10(5) in all 12 patients positive for specific pathogens apart from one case in whom E. coli showing diffuse adherence to HEp-2 cells were identified. Among the remaining 42 specific pathogen-negative patients, 19 (45.2%) also had greater than 10(5) aerobic organisms/ml in the small bowel. Eight strains of Klebsiella from four of the patients were negative for enterotoxin production in a rabbit ileal loop assay and for adherence to HEp-2 cells. In contrast, 28/54 (51.9%) of the same patients had known enteric pathogens in their stools, viz., nontyphoidal Salmonella (8 or 14.8%), Shigella (2 or 3.7%), Campylobacter (1 or 1.9%), ETEC (4 or 7.4%), EPEC (2 or 3.7%), EAEC (7 or 13.0%), and G. lamblia and Entameba histolytica (3 or 5.6%). Further search for potential virulence factors among aerobic bacteria colonizing the upper small intestine in persistent diarrhea is warranted.
Explore the source record for details and available documents.
Simple hematological tests, TLC, DLC, mESR, platelet count, were performed in 128 neonates of which 50 were controls and 78 were cases of suspected septicemia. Thirty three had positive blood cultures and were taken as 'proved' and remaining as 'probable' sepsis. A band cell neutrophil (B/N) ratio of greater than 0.2 was most sensitive index (92%) followed by raised mESR of greater than 8 mm for 1st hour, whereas leukopenia of greater than 5 x 10(3)/mm3 was most specific index (88%) for the diagnosis of sepsis. Thrombocytopenia of less than 1.5 x 10(5)/cu mm was also taken as positive test for sepsis. A combination of three positive tests had highest positive predictive accuracy (94%) for early diagnosis of sepsis, when compared to single test or two positive test combinations. The best combination of tests was B/N ratio, leukopenia and mESR which can be easily done in a side laboratory.
In 10 patients of type I diabetes who were free from clinically apparent vascular disease, platelet functions were studied prior to control, and 10 days and 3 months after strict metabolic control. Platelet hyperactivity, seen as significant shortening of latent period and increase in rate and degree of aggregation, present in patients in the initial uncontrolled state, but absent at the subsequent two periods did not correlate with glycosylation of haemoglobin. Thus control of diabetes mellitus, capable of reversing platelet hyperactivity, is reflected by blood sugar levels, and not by the glycosylation status of haemoglobin.
We studied the profile of nephropathy in 250 patients, 177 males and 73 females, with type 2 diabetes mellitus. The mean age was 55.9 +/- 8.8 years. Therapy for control of diabetes included diet alone in 1.6%, oral hypoglycaemic agents in 90.6% and insulin in 7.8%. Glycaemic control was satisfactory in 4.8%, fair in 41.2% and poor in 54.0%. Blood sugar values were normal without any therapy in 33 out of the 206 patients (16%) after the onset of renal insufficiency. The mean interval between the onset of diabetes and the appearance of proteinuria was 9.5 +/- 7.05 years. Proteinuria appeared within one year in 23 patients (9.2%), 1-5 years in 32 (12.8%), 6-10 years in 86 (34.4%) and more than 10 years in the remaining 109 patients (43.6%). Proteinuria was of nephrotic range in 17.6% of patients. Renal insufficiency was present in 206 (82.4%) patients and occurred 10.5 +/- 7.5 years after the detection of diabetes. Hypertension was present in 61.2% and was first detected 7.5 +/- 7.4 years after onset of diabetes. Endstage renal disease occurred 11.8 +/- 6.8 years after the onset of diabetes mellitus. Thus, clinical evidence of diabetic nephropathy is present in most patients with type 2 diabetes mellitus within a decade after the detection of diabetes. Subsequent progression to end-stage renal failure is rapid in the face of poorly controlled hypertension and hyperglycemia in the economically poor countries.
Three IgM monoclonal antibodies (MoAb) designated as MK2, MK3 and MK5 and specific for the Vi antigen of Salmonella typhi have been produced. These antibodies recognise the epitope involving the O-acetyl group of Vi antigen. In slide agglutination tests, these MoAb's agglutinated all 11 isolates of S. typhi but not the other Gram negative bacteria. This selective reactivity makes them better reagents for the identification of S. typhi than the conventional polyclonal antiserum.
The synthesis of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in rat brain was evaluated. Extracted PAF was characterized using standard HPLC and TLC techniques, and by correlation of its bioactivity with the acetylation state of the 2-position of the molecule. PAF was quantified by bioassay, its ability to cause [3H]serotonin release from washed rabbit platelets. The low basal level of PAF (0.25 +/- 0.15 pmol/g wet wt., mean +/- S.E.) in the brain of the intact rat was greatly increased by intraperitoneal injection of the chemoconvulsant drugs picrotoxin or bicuculline, to levels of 10.68 +/- 2.18 and 4.97 +/- 0.75 pmol/g wet wt., respectively. Electroconvulsion also increased brain PAF, to 1.76 +/- 0.30 pmol/g wet wt. Equivalent experiments using bicuculline in the isolated perfused rat brain yielded qualitatively similar results, indicating that the production of PAF in the brain is independent of systemic metabolism. When a 32P-labeled nerve-ending (synaptosome) preparation from rat brain was challenged with synthetic PAF (denoted AGEPC) at 0.1 nM concentration, responses were observed consistent with accelerated turnover of polyphosphoinositides. AGEPC also caused an increase in the Na+-Ca2+ exchange of synaptic membrane vesicles. Furthermore, AGEPC infused into the vasculature of the isolated perfused rat brain caused changes consistent with an increase in blood-brain barrier permeability, although AGEPC did not itself significantly penetrate the blood-brain barrier. It is concluded from these studies that PAF is synthesized within the rat brain in response to convulsant stimuli and that one of its effects is to accelerate synaptic polyphosphoinositide turnover. In addition, circulating PAF can influence blood-brain barrier permeability without itself penetrating the blood-brain barrier.
Studies of vitamin D-dependent 28-kilodalton calcium binding protein (calbindin D28) have been hindered by difficulties in purifying large amounts of the protein. In order to overcome this problem, we cloned and expressed a full-length rat brain calbindin D28 cDNA. In addition, we isolated and purified to homogeneity, native rat brain calbindin D28. The isolated native protein has an apparent molecular mass of 27 kDa and properties similar to those of the well-characterized chicken calbindin D28. It has an acidic isoelectric point (approximately 4.5), a high affinity for calcium, and an amino terminus blocked to Edman degradation. The properties of the native and the recombinant proteins were examined by gel electrophoresis, isoelectric focusing, protein sequencing, amino acid composition analysis, and calcium binding assays. We demonstrated that: (i) the authentic and the full-length recombinant proteins have similar molecular weights and isoelectric points; (ii) the proteins have the same amino acid composition; (iii) the proteins bind calcium in a similar manner; (iv) the absence of a blocking NH2-terminal group in the recombinant protein does not appreciably influence the binding of calcium. To further examine the calcium binding properties of this protein, we constructed deletion mutants lacking one or both of the two putative degenerated calcium binding sites (EF hand regions). These deletions resulted in smaller proteins that still bound calcium. The ability to express and purify calbindin D28 and mutants thereof should allow the systematic elucidation of structure-function relationships in this class of calcium binding proteins.
The role of breast milk antirotavirus immunoglobulin A (IgA) and trypsin inhibitors in limiting the acquisition of rotavirus infection during the initial 5 days of life was evaluated among 42 exclusively breast-fed hospital-born infants, 22 of whom experienced rotavirus infection. The mean concentrations of antirotavirus IgA (ELISA Units) in the breast milk of mothers of the 22 rotavirus-infected neonates was 130.4 +/- 46.4; the corresponding value in 20 noninfected neonates was 384.3 +/- 328.3 (P less than 0.001). Similarly, the trypsin inhibitory capacity (mumols/mt/ml) of breast milk in the rotavirus-infected group was significantly lower (0.109 +/- 0.095) than that in the noninfected group (0.376 +/- 0.191; P less than 0.001). The trypsin inhibitory capacity of milk showed an inverse correlation with infant stool tryptic activity (P less than 0.01). Our results indicate that the acquisition of rotavirus infection during the early neonatal period depends on the concentrations of antirotavirus IgA and trypsin inhibitors in human milk and that protection is mediated by high levels of these antiviral factors.