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Biomedical subjects

R Narasimhan

Publications and source records attributed to R Narasimhan.

At least 19 recordsLinked to original sources
PubMed2005

Tuberculin reactivity in tuberculous meningitis.

OBJECTIVE: To study tuberculin reactivity in childhood tuberculous meningitis both in clinical and histopathological (HP) context. METHODOLOGY: Children with tuberculous meningitis (TBM) were given tuberculin test by Mantoux technique, which was read at the end of 72 hours after the placement of skin test. Histopathological examination of the punch biopsy specimen of the tuberculin test site was performed and histopathological grading of the tuberculin reaction was compared with clinical reaction and clinical parameters. RESULTS: Of the 50 children studied, 68% of them were malnourished and 42% had BCG scar. Tuberculin test was positive in 22 (44%) cases. Spearman analysis showed negative correlation between stage of TBM and the size of tuberculin reaction. BCG status did not affect the size of tuberculin reaction. Histopathological grade of the tuberculin reaction was found to be directly proportional to the size of the tuberculin reaction and it was not affected by the stage of TBM. CONCLUSION: Tuberculin positivity is low in TBM irrespective of the nutritional status. At least some degree of inflammatory reaction can be seen at the site of tuberculin administration. In tuberculin negative cases, varying grades of cellular response in the absence of clinical induration can be seen in histopathology.

BCG Vaccine↗
PubMed2004

Extra-articular pigmented villonodular synovitis.

Villonodular synovitis are a group of idiopathic lesions that affect the synovial surfaces of joints, tendon sheaths, and bursae, causing tumor-like lesions. Pigmented villonodular synovitis rarely affects the tendon sheaths; its occurrence in extra-articular sites is uncommon. This case is presented for the rarity of occurrence. The literature is also reviewed.

Journal Article↗
PubMed2003

Laboratory testing protocol to identify critical factors in bacterial compliance monitoring.

This research focused on providing guidelines for water utilities on the collection and handling of routine bacteriological samples and in developing scientifically-based approaches in selecting the most representative sampling locations. A laboratory-scale pilot distribution system was designed comprising two parallel loops, one using unlined cast-iron pipe and one using PVC pipe. Each loop contained six sampling ports, including (1) a distribution main dead end faucet, (2) one long (5.5 m; 18 feet) and (3) one short (0.3 m; 1 foot) household copper service line with threaded hose-bibb taps, (4) one hose-bibb with welded faucet, (5) one dedicated sampling port (modeled after a manufacturer's specifications) and (6) one laboratory-style (PVC) stop-cock sampling port. Residual chlorine concentrations were maintained at 0, 0.5, 1.5 and 2.0 mg/L stages during the course of the experiment. Bacterial samples were collected from the different sampling ports and assayed by membrane filtration and/or spread plate. Nutrient and R2A agars were used for heterotrophic plate counts (HPC), m-Endo agar for total coliform (TC) counts and Chromocult agar for injured bacterial analyses. Several methods of sample collection were tested using various combinations of flushing and tap disinfection, including "first flush" (no flushing, without tap disinfection), flushing only, tap disinfection only (using alcohol or hypochlorite solution) and flushing coupled with tap disinfection. The results indicated that the bacterial counts in samples drawn from dead ends were not significantly different from counts in samples from the other sample port configurations. First flush samples consistently produced the highest bacterial count results. Bacterial counts in samples from the long household copper service line were typically three orders of magnitude higher than in samples from the other sample ports. Thus, there is evidence that long copper household service connections may be unsuitable sample tap configurations for collecting samples intended to represent microbial quality in the distribution system.

Enterobacteriaceae↗
PubMed1999

Microbial dynamics in oil-impacted prairie soil.

A remote site in the Tallgrass Prairie Preserve (Osage County, OK) was contaminated with crude oil by a pipeline break in 1992. In 1996, the contaminated soil was bioremediated by blending with uncontaminated soil, prairie hay, buffalo manure, and commercial fertilizers, and spreading in a shallow layer over uncontaminated soil to create a landfarm. The landfarm was monitored for two years for aerobic and anaerobic bacteria, soil gases indicative of microbial activity, and for changes in the concentration of total petroleum hydrocarbons (TPH). Levels of hydrocarbon degraders and soil gas indicators of aerobic degradation were stimulated in the landfarm during the first warm season relative to uncontaminated prairie soil. However, these same indicators were less conclusive during the second warm season, indicating depletion of the more easily degradable hydrocarbons, although the landfarm still contained 6,800 mg/kg TPH on the average at the beginning of the second warm season. Methane formation and methanogen counts were clearly stimulated in the first warm season relative to uncontaminated prairie soil, indicating that methanogenesis plays an important role in the mineralization of hydrocarbons even in these shallow soils.

Journal Article↗
PubMed1996

Fine-needle aspiration cytology in the diagnosis of superficial lymphadenopathy: an analysis of 2,418 cases.

During a period of 5 yr, 2,418 fine-needle aspirations (FNA) were performed on 2,216 patients with superficial lymphadenopathy. Chronic nonspecific lymphadenitis was the commonest inflammatory lesion followed by tuberculosis. Among malignant lesions, metastatic tumors were most common followed by non-Hodgkin's lymphoma. The FNAC findings were correlated with subsequent histopathological diagnosis in 1,041 cases. The sensitivity rates of FNAC in tuberculosis, metastatic tumors, Hodgkin's disease, and non-Hodgkin's lymphoma were found to be 83.3, 97, 30, and 80.3%, respectively, the specificity being 94.3, 98.9, 98.6, and 95.4% in the same order. Immunocytochemical tests performed on the aspirated material helped in classifying the metastatic poorly differentiated tumors and confirming the diagnosis of non-Hodgkin's lymphomas. Effects of FNA on subsequent biopsy in 81 lymph nodes with benign hyperplasia were studied and showed that aspiration does not interfere with subsequent histologic assessment. Thus FNAC is a simple, inexpensive procedure, and when complemented by appropriate immunocytochemical studies is accurate and reliable for routine diagnosis of lymphadenopathy.

Biopsy, Needle↗
PubMed1993

Accuracy of fine needle aspiration cytology of abdominal masses without radiological guidance.

This study was undertaken to evaluate the accuracy of FNAC of abdominal masses without the help of radiological guidance and to determine factors which affect the outcome of the procedure. Five hundred consecutive patients were studied. FNAC was reported by a single cytopathologist without knowledge of subsequent histology. In calculating indices of accuracy of FNAC only those patients in whom both FNAC and histology reports were available (N = 383) were considered. The overall incidence of unsatisfactory specimens was 5.6%. Consistency of the mass did not affect accuracy of FNAC. However, age (below 12 years) plane of the swelling, mobility of mass and size of the swelling, all significantly affected the adequacy of cytological yield. The overall true positive rate was 100.0% and there were no false positives. The true negative rate was 40.2% and false negative rate was 70.9%. The high false negative rates in hepatic and pancreatic lesions can be reduced by imaging techniques. Luminal organs had poor accuracy rates. The overall accuracy rate was 73.5%, comparable to that reported in literature. A positive diagnosis of malignancy had a 100% predictive value. Overall, it appears that nonguided FNAC is as accurate as guided FNAC except for very small lesions or discrete lesions such as hepatic secondaries where guidance may be useful.

Abdominal Neoplasms↗
PubMed1991

Coexisting tuberculosis and carcinoma of the colon.

Four cases of coexisting tuberculosis and carcinoma of the colon (CTCC) are reported. All the patients were female and the mean age was 49 +/- 11 years. The tumour involved the right colon in three patients and the distal transverse colon in the other. The two lesions coexisted at the same site in two patients. Mucinous carcinoma was the predominant type seen in three patients. The characteristics of patients with CTCC were compared with those of 54 patients who had carcinoma of the colon (CC) and 17 patients with tuberculosis of the colon (TC) seen during the same period. All the four CTCC patients were female, compared with 13 of 54 patients with CC (P less than 0.001). These two groups were similar in mean age, anatomic sites and histopathological tumour types. The CTCC patients were significantly older than the TC patients (49 +/- 11 years vs 34 +/- 10 years, P less than 0.05). The sex distribution of TC patients was similar to that of CTCC patients, 14 of 17 patients being female. All TC lesions were confined to the right colon. The present study showed a high frequency of carcinoma in patients with colonic tuberculosis, signifying the need for epidemiological and histopathological investigations into the aetiological relationship between the two diseases, the possibility of which was suggested recently by Japanese researchers. The relevant literature on 58 previously reported patients with CTCC was reviewed.

Adenocarcinoma↗
PubMed1990

Role of fine needle aspiration cytology in the management of thoracic lesions.

Fine needle aspiration cytology was performed on 121 occasions in 100 patients with various thoracic lesions. The investigation was performed chiefly with the help of straight and lateral chest skiagrams regardless of the size or depth of the lesion. The cellular yield was 87.6%. Positive diagnosis of malignancy could be made in 50 cases. The histopathological correlation in malignant cases was 80%. Non-malignant cytology including neoplastic and inflammatory pathology was also found useful in patient management. This report highlights the versatile role of this procedure in arriving at a diagnosis and planning the treatment for malignant as well as non-malignant thoracic diseases.

Adolescent↗
PubMed1990

Problems and limitations with fine needle aspiration cytology of solitary thyroid nodules.

Fine needle aspiration cytology (FNAC) is a widely employed tool in the investigative work-up of patients with single thyroid nodules. Although its advantages are well documented, the limitations and problems in interpretation of FNAC in this condition are not well known. Experience with FNAC in 150 patients with solitary thyroid nodules is presented, highlighting the pitfalls of this technique. There was an inadequate specimen rate of 22.7% which declined with increasing experience. Follicular carcinomas could not be differentiated from follicular adenomas by cytology. Difficulties may arise in the detection of papillary carcinomas due to occult lesions, mixed papillary and follicular carcinomas or due to associated thyroid pathology. False positivity is, however, much rarer and is generally due to cellular adenomatous goitres with marked papillary activity. In view of these cytologic limitations, care must be exercised by the treating physician in interpreting cytological results.

Adenoma↗
PubMed1983

Studies of the biosynthesis and metabolism of rat testicular galactoglycerolipids.

1-O-Alkyl-2-O-acyl-3-O-beta-D-(3'-sulfatoxygalactopyranosyl)-sn- glcerol (SGG) and its nonsulfated analog (GG) are the major glycolipids of rat testis. Aspects of the biosynthesis and metabolism of these two lipids have been investigated by determining their specific activities at various times after injection of [16-14C]palmitic acid, [1-14C]cetyl alcohol, and D-[1-14C]galactose into the testes of the adult rats. Evidence was obtained from studies with each of these three radioactive compounds that is consistent with the interpretation that GG exhibits a precursor relationship to SGG in vivo. The turnover time of GG, as estimated from the use of each of the three precursors, ranged between 21 and 69 h. In contrast, a slow increase of radioactivity in SGG was observed following injection of each of the three precursors, a plateau value being reached between 72 and 168 h. The radioactivity in the acyl, alkyl, and galactosyl moieties of SGG thereafter remained quite constant for another 21 days. Small amounts of monoalkylmonoacylglycerol were detected in rat testis. Radioactive studies indicated that this compound could be a precursor of GG and (or) monoalkyldiacylglycerol, another lipid that was also detected in rat testis. The results are consistent with the concept that the synthesis of SGG occurs primarily at an early stage of spermatogenesis and that the various moieties of this lipid exhibit almost complete metabolic stability during the subsequent complex stages of this process.

Animals↗
PubMed1982

Studies on the glycolipids of human saliva and gastric juice.

It has been reported that both human saliva and gastric juice (cf. Slomiany, B. L., and Slomiany, A. (1980) in Cell Surface Glycolipids (Sweeley, C. C., ed) American Chemical Society Symposium, No. 128, pp. 149-176, American Chemical Society, Washington, D.C.) contain substantial amounts of certain members of a series of novel glucoglycerolipids with a 1-O-alkyl glyceryl ether backbone. We have analyzed the glycolipids present in samples of saliva obtained from 10 individuals and in samples of gastric juice obtained from 5 individuals. In both fluids, compounds corresponding in the properties studied to standards of glucosyl- and lactosylceramides were found to be the major glycolipids. Other more complex glycosphingolipids were also present in smaller amounts. Human saliva was found to contain two glucoglycerolipids that were not detected in gastric juice. Analyses of these compounds indicated that they were mono- and diglucosyl diglycerides and were probably of bacterial origin. Methanolysis of the glycolipid fractions of saliva and gastric juice failed to reveal the presence of any more than traces of 1-O-alkyl glyceryl ethers. Our results do not exclude the possibility that glyceryl ether-containing glucoglycerolipids occur in human saliva and gastric juice. However, at most they would appear to be rather minor components of either fluid.

Chromatography, Thin Layer↗
PubMed1982

Decision analysis and dental malpractice suits.

This article introduced the reader to the basic notions of decision analysis. The generic structure of decisions was introduced by means of an example. Using the concepts for analyzing malpractice suits was then discussed in the context of a hypothetical problem. Two points are worth noting: (1) decision analysis constructs have wide applicability, since the ingredients germane to decision problems across disciplines have important similarities; and (2) the purpose of engaging in formal analysis is to enhance understanding and description of a problem and to aid the decision-maker to be more explicit and more comprehensive in his search for a preferred course of action. Undoubtedly the article has raised some questions in the minds of the readers. In an elementary exposition such as this it is difficult to do full justice to the topics of decision analysis. The following references may be of interest.

Cost-Benefit Analysis↗
PubMed1979

Neutral glycosphingolipids and gangliosides of human lung and lung tumours.

In order to help determine whether alterations of the profiles of glycosphingolipids occur consistently in human tumours, the neutral glycosphingolipids and gangliosides of nine lung tumours (one adenocarcinoma, four squamous cell, two mixed adeno-squamous cell, one large cell and one oat-cell carcinomata) were analysed. The control tissue consisted of adjacent lung; it contained neutral glycosphingolipids corresponding in properties to glucosyl-, lactosyl-, globotriaosyl- and globotetraosyl-ceramides. All of the tumours also contained these four neutral glycosphingolipids. However, in addition, five of the tumours (two of the squamous, the large cell and the two mixed adeno-squamous cell carcinomata) contained neutral glycosphingolipids corresponding in properties to lactotriaosyl- and neolactotetraosyl-ceramides; these same tumours also exhibited higher amounts of lactosylceramide than the other tumours analysed. Both of the two former neutral glycosphingolipids and very substantial amounts of the latter neutral glycosphingolipid were detected in pneumonic lung and in polymorphonuclear leucocytes; it thus appears possible that these particular compounds were derived from these latter cells rather than from the tumour cells. The ganglioside patterns of the tumours were almost equivalent in complexity to that exhibited by the control lung tissue. This study shows that the profiles of two major classes of glycosphingolipids (neutral glycosphingolipids and gangliosides) occurring in lung tumours are almost as complex as those of the parent tissue, a finding in contrast with the notably simplified patterns of these lipids found in many cancer cells grown in vitro. It also suggests that when lactotriaosyl- and neolactotetraosyl-ceramides and high amounts of lactosylceramide are detected in human tumours, the possibility must be considered that these compounds are derived from polymorphonuclear leucocytes.

Carbohydrates↗