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Biomedical subjects

K R Rao

Publications and source records attributed to K R Rao.

At least 55 records · Page 3Linked to original sources
PubMed1988

Alterations in the length of jejunal villi in mice irradiated with graded doses of X rays.

The length of villi protruding into the jejunal lumen influences the absorptive surface involved in digestion. Since it is an important functional end-point, a correlation between the X-ray dose applied and the average length of jejunal villi was investigated, with the possibility of using it as a radiobiological test system. Mice were given whole-body irradiation in the low- (4-7 Gy) or high-dose (9-12 Gy) range in a single fraction. Villus length was measured in arbitrary units from stained histological sections. It was found that villus length was affected by both the dose ranges used, but the effect observed in the low-dose range was not dose-related, whereas in the high-dose range there was a correlation between the radiation dose applied and the reduction in the average length of villi. Therefore, it is not suitable as an assay for low doses and for high doses there is already a test system (the microcolony survival assay) which is more practical and widely used. Factors which may influence villus length as well as the basic mechanisms involved are reviewed briefly. Experimental data presented indicate that the villus length may also be dependent on the number of crypts per jejunal circumference.

Animals↗
PubMed1988

Studies on some kinetic parameters of aminotransferases in tissues of the snail, Pila globosa (Swainson) during malathion intoxication.

The aspartate and alanine aminotransferases in the tissues of the snail, Pila globosa showed high catalytic potentials (low Km and high Vmax) during malathion exposure in vivo. In vitro addition of different concentrations of malathion did not influence aminotransferase activity. The results are discussed in relation to the regulative influence of the intracellular environment of the cell.

Alanine Transaminase↗
PubMed1987

Position 3 analogues of a crustacean pigment-dispersing hormone: synthesis and biological activity.

In an effort to explain the difference in potencies between the two characterized crustacean pigment-dispersing hormones (alpha-PDH; beta-PDH) and to define a role for residue 3 in these octadecapeptide hormones, we have synthesized and purified seven position 3 alpha-PDH analogues ([Ala3], [Ile3], [Asn3], [Gln3], [Asp3], [Glu3], and [Lys3]alpha-PDH). When tested for melanophore pigment-dispersing activity in destalked Uca, [Glu3]alpha-PDH was found to be 325% more potent than alpha-PDH. Reduced potencies were observed for the [Asp3] (58%), [Asn3] (26%), [Gln3] (11%), and [Ala3] (8%) derivatives. Much lower potencies were displayed by the [Lys3] and [Ile3] analogues (0.73% and 0.66%, respectively). These results suggest that the position 3 side chain carboxylate anion of [Glu3]alpha-PDH stabilizes the active receptor-bound conformer through a charge-charge interaction.

Amino Acid Sequence↗
PubMed1987

Primary structure of an analog of crustacean pigment-dispersing hormone from the lubber grasshopper Romalea microptera.

An octadecapeptide capable of inducing pigment dispersion in the chromatophores of the fiddler crab Uca pugilator has been isolated from lyophilized heads of the lubber grasshopper Romalea microptera. This pigment-dispersing factor (PDF) was purified by gel filtration, ion-exchange chromatography, partition chromatography, and reversed-phase high performance liquid chromatography. Automated gas-phase sequencing, followed by the identification of the carboxyl-terminal amide, established the primary structure of this PDF as Asn-Ser-Glu-Ile-Ile-Asn-Ser-Leu-Leu-Gly-Leu-Pro-Lys-Leu-Leu-Asn-Asp-Ala- NH2. This structure was confirmed by chemical synthesis and by demonstrating that the synthetic and native PDF displayed identical chromatographic behavior and biological activity. The Romalea PDF is structurally related to the crustacean pigment-dispersing hormones (PDHs), which are also octadecapeptides. The sequence of grasshopper PDF shows 78% homology with beta-PDH (from the crabs U. pugilator and Cancer magister) and 50% homology with alpha-PDH (from the prawn Pandalus borealis). This study provides the first direct chemical evidence for the structural relatedness of insect PDF to the crustacean PDHs, thus identifying them as an authentic family of arthropod peptides.

Amino Acid Sequence↗
PubMed1987

Five years' experience of bacteraemia in sickle-cell anaemia.

In a review of all adults admitted with sickle-cell anaemia to Cook County Hospital between January 1980 and April 1985, 15 instances of bacteraemia were identified. In these patients, bacteraemia was characterised by slow onset, an identifiable focus of infection and lack of hypotension or abnormal coagulation of the blood. The organisms, most often isolated were Escherichia coli and Salmonella species. Two patients died, both with Salmonella enteritidis bacteraemia. Neither death could be attributed to the acute effects of infection. The outcome of bacteraemia in adults with sickle-cell anaemia appears to be more favourable than that in children.

Adult↗
PubMed1987

Erythrocytic ecdysis in smears of EDTA venous blood in eight patients with sickle cell anemia.

The light-microscope finding of red cell membrane fragments in the form of long filamentous processes and myelin bodies in the blood smears of a patient with sickle cell anemia has recently been described. This phenomenon has been termed erythrocytic ecdysis. We examined the blood smears of all sickle cell anemia patients admitted to the Cook County Hospital and those attending the hemoglobinopathy clinic between October 1979 and December 1981. Nine instances of erythrocytic ecdysis were uncovered. Associated clinical conditions included congestive heart failure, acute viral syndrome, pneumonia, and metastatic malignancy. Transient ecdysis associated with congestive heart failure was noted for one patient during two separate admissions one year apart. Ecdysis is a transient form of erythrocytic fragmentation occurring in sickle cell anemia. Its pathogenesis is unknown. The role of regional circulatory stasis and hypoxia in the induction of erythrocyte membrane damage in sickle cell anemia needs investigation.

Adult↗
PubMed1987

Glycosylated hemoglobins in a diabetic patient with sickle cell anemia.

Results of analysis of blood samples from a diabetic sickle cell anemia (SS) patient and 4 nondiabetic SS patients for glycosylated hemoglobins by Bio-Rex 70 chromatography, high-pressure liquid chromatography, and affinity chromatography are presented. Glycosylated components of Hb S and Hb A2 and total glycosylated hemoglobins were quantitated in this manner. The levels of the various glycosylated hemoglobins were increased twofold in the diabetic patient compared to nondiabetic SS patients. The glycosylated hemoglobin levels in the diabetic SS patient and in the nondiabetic SS patients, however, were significantly lower than the levels normally seen in nonsickle diabetics and normal adults, respectively. In contrast to a previously reported diabetic SS patient, the present case appears to be not severely affected by sickle cell disease.

Adult↗
PubMed1987

Variations of pion RBE in a volume with an asymmetric beam configuration.

The relative biological effectiveness for the radiation response of mouse jejunum for pions was determined in a clinically relevant asymmetric treatment geometry. A cylindrical volume of 570 ccm, with mouse holders in proximal and distal positions, was irradiated by spot scan technique with a sector of 31 concentric pion beams. The physical dose distribution within the treatment field was homogeneous and the average dose rate was 8.5 cGy/min. The aim was to determine RBE differences between the proximal and distal edge of the field and to compare it with the predictions. The RBE, relative to 200 kVp X-rays, was 1.3 for proximal position and 1.4 for the distal one. The results are in agreement with the calculations of the therapy planning computer program and with the microdosimetric characteristics at the two positions. The variation of the RBE is smaller than for the same field irradiated by a single pion beam.

Animals↗
PubMed1986

Hepatic metastatic thymoma and myasthenia gravis twenty-two years after the apparent cure of an invasive thymoma. A case report and review of the literature.

We report the case of a 62-year-old woman who presented in myasthenic crisis 22 years after radiation- and chemotherapy of an invasive thymoma which occurred during pregnancy. There was no evidence of recurrence of the thymoma at its original site, but an isolated hepatic metastasis was discovered. Biopsy of the mass revealed a spindle cell thymoma, whereas the original histology was that of a mixed round and spindle cell thymoma with moderate lymphocytic infiltration. The patient expired in spite of treatment with steroids, pyridostigmine bromide and plasma exchange on the one hand and cyclophosphamide with adriamycin on the other. To our knowledge, 22 years is the longest reported interval for the appearance of metastatic thymoma and myasthenia gravis after the diagnosis and apparent cure of a primary thymoma. This is also the only reported case of thymoma occurring during pregnancy but not associated with a rapidly fatal outcome.

Female↗
PubMed1985

Cross-phyletic bioactivity of arthropod neurohormones and molluscan ganglion extracts: evidence of an extended peptide family.

Two structurally related arthropod neuropeptides, red pigment concentrating hormone (RPCH) and adipokinetic hormone (AKH), are potent excitors of the heart of the clam Mercenaria mercenaria. The response is bimodal: whereas the threshold for affected hearts is 1-3 X 10(-9) M, about 40% of the preparations are virtually unresponsive. Aqueous extracts of Mercenaria ganglia contain a substance which concentrates the red pigment in the erythrophores of intact destalked Uca pugilator and even of its isolated legs. This substance is retained on Sephadex G-15 and co-elutes with synthetic shrimp RPCH. The active fractions also concentrate the erythrophores and the leucophores of destalked shrimp (Penaeus). Neither dopamine nor the molluscan neuropeptide FMRFamide had any chromatophorotropic effect in these assays. The activity of the ganglion extracts was abolished by digestion with chymotrypsin. In conclusion, molluscan ganglion extracts contain a peptide factor, possibly an analog of RPCH, that concentrates the pigments of crustacean chromatophores by a direct action on the cells.

Animals↗
PubMed1985

Combined action of carbaryl and phenthoate on tissue lipid derivatives of murrel, Channa punctatus (Bloch).

The levels of total lipids, free fatty acids, cholesterol, and lipase activity were studied in selected tissues of Channa punctatus Bloch during individual and combined exposures of carbaryl and phenthoate. The total lipid levels decreased with elevated levels of free fatty acids and lipase activity during all exposures, suggesting increased lipid hydrolysis to derive energy as an attempt to face the pesticide toxic stress. The cholesterol levels showed an elevated trend. These results were discussed in relation to induced glyconeogenesis and diversion of acetyl-coA to cholesterol synthesis during pesticide treatment. The effect produced by carbaryl + phenthoate treatment remained higher than either of the pesticides alone, suggesting the manifestation of an additive effect.

Animals↗