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Biomedical subjects

C N Rao

Publications and source records attributed to C N Rao.

At least 73 records · Page 4Linked to original sources
PubMed1982

Isolation of a subunit of laminin and its role in molecular structure and tumor cell attachment.

Laminin, the glycoprotein of basement membranes, migrates as two components of 200 kilodaltons (kDa) (alpha subunit) and 400 kDa (beta subunit) after reduction on polyacrylamide gel electrophoresis. We have isolated the alpha subunit and studied its structure by electron microscopy and its function as an attachment factor for tumor cells. Using selective proteolysis of laminin by alpha-thrombin, the beta subunit was removed without any change in the quantity or size of the alpha subunit. Removal of the beta subunit caused a 35-40% decrease in the total mass of the laminin molecule. The alpha and beta subunits differed by 50-fold in the amount of reducing agent required for complete migration on polyacrylamide gels. By electron microscopy, the whole laminin molecule appeared as a "cross" with three identical short arms (37 nm) and one long arm (75 nm). The alpha subunit examined by electron microscopy was missing the long arm and had no change in the length of the three short arms. This subunit of laminin mediated the attachment of human squamous carcinoma cells to type IV collagen. Such attachment properties were lost after pepsin treatment which is known to remove the globular end regions of the short arms. We conclude that the beta subunit of laminin is embodied in the long arm of the molecule and that the alpha subunit consists of three similar chains of 200 kDa. The globular end regions of the laminin short arms are required for the attachment of tumor cells to type IV collagen.

Animals↗
PubMed1982

Increased content of Type V Collagen in desmoplasia of human breast carcinoma.

Type V (AB) collagen is present in increased amounts in desmoplasia of human breast carcinoma. Type V collagen occurs as linear deposits in the interstitium (desmoplastic stroma surrounding the tumor), as demonstrated by immunofluorescence and immunoperoxidase techniques utilizing antibodies to Type V collagen. In contrast, no demonstratable Type V occurs in the interstitium of fibroadenoma, fibrocystic disease, or normal breast tissue. As identified and quantitated by pepsin extraction, salt fractionation, and polyacrylamide gel electrophoresis, Type V constitutes 10% +/- 5% of all interstitial collagens (Types I, III, and V) in desmoplasia, compared with 1.5% +/- 0.5% in fibroadenoma and less than 0.1% in all types of fibrocystic disease, including sclerosing adenosis, and less than 0.1% in normal breast tissue. For infiltrating ductal carcinoma, Type V collagen is not secreted by the invasive carcinoma cells, nor is it present in an extracellular basement membrane location. By immunohistologic methods, Type V collagen can be seen exclusively in the desmoplastic stroma. The authors propose that desmoplasia of human breast carcinoma manifests a characteristic collagen profile and that the increased Type V may be produced by specialized cells such as myofibroblasts in the interstitium, which are recruited in response to invasive carcinoma.

Adenocarcinoma, Scirrhous↗
PubMed1981

Systematic variation in bond lengths of peptides.

The lengths of the carbonyl as well as of the adjacent C-N and C-C bonds in peptides are shown to vary systematically with the central C-N bond length. Results of ab initio calculations on N-methylacetamide and its Li+, Na+ and Mg2+ complexes are also discussed.

Acetamides↗
PubMed1981

Primary amyloidosis of urethra.

Primary amyloidosis is a rare disease. Only 10 cases of amyloid tumor of the urethra have been reported previously, with this being the eleventh case. Because of its rarity and because it stimulates carcinoma, biopsy is essential for definitive diagnosis and treatment. The literature is reviewed, and symptomatology, pathology, and management are discussed.

Amyloidosis↗
PubMed1980

Infrared studies on the conformation of synthetic alamethicin fragments and model peptides containing alpha-aminoisobutyric acid.

Infrared studies of synthetic alamethicin fragments and model peptides containing alpha-aminoisobutyric acid (Aib) have been carried out in solution. Tripeptides and larger fragments exhibit a strong tendency to form beta turns, stabilized by 4 leads to 1 10-atom hydrogen bonds. Dipeptides show less well-defined structures, though C5 and C7 conformations are detectable. Conformational restrictions imposed by Aib residues result in these peptides populating a limited range of states. Integrated intensities of the hydrogen-bonded N-H stretching band can be used to quantitate the number of intramolecular hydrogen bonds. Predictions made from infrared data are in excellent agreement with nuclear magnetic resonance and X-ray diffraction studies. Assignments of the urethane and tertiary amide carbonyl groups in the free state have been made in model peptides. Shifts to lower frequency on hydrogen bonding are observed for the carbonyl groups. The 1--6 segment of alamethicin is shown to adopt a 3(10) helical structure stabilized by four intramolecular hydrogen bonds. The fragments Boc-Leu-Aib-Pro-Val-Aib-OMe (12--16) and Boc-Gly-Leu-Aig-Pro-Val-Aib-OMe (11--16) possess structures involving 4 leads to 1 and 5 leads to 1 hydrogen bonds. Supporting evidence for these structures is obtained from proton nuclear magnetic resonance studies.

Alamethicin↗
PubMed1980

Absorption and retention of magnesium and some trace elements by man from typical Indian diets.

Availability of magnesium and some trace elements in Indian diets has been studied in human adults. Absorption of trace elements from the diets as a percentage of intake was: chromium 60, copper 18, magnesium 34, manganese 14 and zinc 16. Daily dietary intakes of 51.5 micrograms of chromium, 1.73 mg copper and 4.1 mg of manganese were found to be necessary to keep the subjects in balance in respect to these elements.

Absorption↗
PubMed1980

Effect of bioflavonoids on lysosomal acid hydrolases and lysosomal stability in adjuvant-induced arthritis.

In rats with adjuvant-induced arthritis, the effect of (+)-catechin (CA) and 0-(beta-hydroxyethyl) rutosides (HR) on the activity of certain lysosomal acid hydrolases, viz., beta-glucuronidase, beta-N-acetyl glucosaminidase and cathepsin D in serum, liver, kidney and spleen and the stability of liver lysosomes was studied. The activity of these enzymes in arthritic tissues and serum increased significantly. The total activity of beta-glucuronidase in the lysosome-rich fraction from arthritic liver was appreciably decreased, while its release was significantly increased. These results demonstrate the fragility of lysosomes in arthritic tissues. Administration of CA or HR to the arthritic animals was found to have a prophylactic action by stabilizing liver lysosomes and reducing the free lysosomal enzyme activities in serum, liver, kidney and spleen. CA was more effective than HR.

Animals↗
PubMed1977

Primary renal artery dissecting aneurysm: a review.

Primary dissecting aneurysms of the renal artery are exceedingly rare. Our recent encounter with a patient with this condition prompted a review of the literature. The diagnostic and therapeutic problems in 30 patients were analyzed and guide lines for proper management were discussed. The triad of flank pain, hematuria and hypertension of acute onset in the absence of urinary obstruction should suggest this rare condition.

Adult↗
PubMed1975

Influence of varying energy intake on nitrogen balance in men on two levels of protein intake.

Effect of changing energy levels of the diet at constant protein intakes on nitrogen balances in five young men were studied at two levels of protein--40 and 60 g. Nitrogen balance increased with increase in energy intake at both levels of protein. This was brought about primarily by a reduction in urinary nitrogen excretion. Energy levels at which nitrogen equilibrium was obtained were different for the two levels of protein intake. At 40 g protein intake the energy intake required for zero nitrogen balance was 2,249 kcal, while it was 2,066 kcal when the diet provided 60 g protein.

Adult↗