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R Narasimhan

Publications and source records attributed to R Narasimhan.

13 recordsLinked to original sources
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↗
PubMed1978

Comparative study of the glycosphingolipids of chicken bursa of Fabricius and of chicken, rat and human thymus.

1. The glycosphingolipid compositions of the thymus and bursa of Fabricius of young male chickens were compared. The two tissues were found to contain complex mixtures of both neutral glycosphingolipids and gangliosides. Both tissues contained mono-, di-, tri-, tetra- and penta-glycosylceramides; the pentaglycosylceramide displayed a reaction of identity with authentic Forssman antigen when tested against a specific anti-(Forssman antigen) serum. The ganglioside G(m3) containing N-acetylneuraminic acid was the principle ganglioside of both tissues. 2. The thymus contained appreciable amounts of the simple ganglioside N-acetylneuraminylgalactosylceramide, a compound not found in the bursa. The ganglioside G(d3) (disialohaematoside) was detected in both tissues. 3. Rat and human thymus, like sheep thymus (Narasimhan, Hay, Greaves & Murray (1976) Biochim, Biophys. Acta 431, 578-591), both contained a tetraglycosylceramide species as their most complex neutral glycosphingolipid and possessed little or no Forssman antigen. They also contained a complex mixture of gangliosides. 4. The possible significance of these results is briefly discussed.

Animals↗
PubMed1976

Studies on the glycolipids of sheep thymus and of normal and concanavalin A-stimulated sheep peripheral lymphocytes.

The neutral glycolipids and gangliosides of sheep thymus and of sheep peripheral lymphocytes were compared. The patterns of both of these major classes of glycolipids were more complex in thymus than in the lymphocytes. The incorporation of radioactivity from D-[1-14C]galactose into the individual glycolipids of control and concanavalin A-stimulated sheep peripheral lymphocytes was also studied. A marked enhancement of incorporation into trihexosylceramide and an alteration of the pattern of incorporation into gangliosides were noted in the mitogen-treated cells. The results suggest that significant alterations of glycolipid composition and metabolism may occur during at least certain stages of lymphocyte differentiation.

Animals↗