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Biomedical subjects

K R Rao

Publications and source records attributed to K R Rao.

At least 19 recordsLinked to original sources
PubMed1991

Pigment-dispersing hormone-immunoreactive neurons and their relation to serotonergic neurons in the blowfly and cockroach visual system.

The pigment-dispersing hormone (PDH) family of neuropeptides comprises a series of closely related octadecapeptides, isolated from different species of crustaceans and insects, which can be demonstrated immunocytochemically in neurons in the central nervous system and optic lobes of some representatives of these groups (Rao and Riehm 1989). In this investigation we have extended these immunocytochemical studies to include the blowfly Phormia terraenovae and the cockroach Leucophaea maderae. In the former species tissue extracts were also tested in a bioassay: extracts of blowfly brains exhibited PDH-like biological activity, causing melanophore pigment dispersion in destalked (eyestalkless) specimens of the fiddler crab Uca pugilator. using standard immunocytochemical techniques, we could demonstrate a small number of pigment-dispersing hormone-immunoreactive (PDH-IR) neurons innervating optic lobe neuropil in the blowfly and the cockroadh. In the blowfly the cell bodies of these neurons are located at the anterior base of the medulla. At least eight PDH-IR cell bodies of two size classes can be distinguished: 4 larger and 4 smaller. Branching immunoreactive fibers invade three layers in the medulla neuropil, and one stratum distal and one proximal to the lamina synaptic layer. A few fibers can also be seen invading the basal lobula and the lobula plate. The fibers distal to the lamina appear to be derived from two of the large PDH-IR cell bodies which also send processes into the medulla. These neurons share many features in their lamina-medulla morphology with the serotonin immunoreactive neurons LBO-5HT described earlier (see Nässel 1988). It could be demonstrated by immunocytochemical double labeling that the serotonin and PDH immunoreactivities are located in two separate sets of neurons. In the cockroach optic lobe PDH-IR processes were found to invade the lamina synaptic region and form a diffuse distribution in the medulla. The numerous cell bodies of the lamina-medulla cells in the cockroach are located basal to the lamina in two clusters. Additional PDH-IR cell bodies could be found at the anterior base of the medulla. The distribution and morphology of serotonin-immunoreactive neurons in the cockroach lamina was found to be very similar to the PDH-IR ones. It is hence tempting to speculate that in both species the PDH- and serotonin-immunoreactive neurons are functionally coupled with common follower neurons. These neurons may be candidates for regulating large numbers of units in the visual system.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1991

Primary structure and relative potency of an analog of beta-PDH (pigment-dispersing hormone) from the crayfish Procambarus clarkii.

A pigment-dispersing hormone (PDH) from eyestalks of the crayfish Procambarus clarkii was purified by gel filtration, cation-exchange chromatography, partition chromatography, and reversed-phase HPLC. Based on automated sequencing and by the identical chromatographic behavior of the native PDH and the synthetic amidated form of the deduced sequence, the primary structure of Procambarus PDH has been established as: Asn-Ser-Glu-Leu-Ile-Asn-Ser-Ile-Leu-Gly-Leu-Pro-Lys-Val-Met-Asn-Glu-Ala- NH2. This peptide differs from beta-PDH of the fiddler crab Uca pugilator at a single position, Glu17 in place of Asp17. Because of this substitution, Procambarus PDH was 4 to 7-fold less potent than beta-PDH in causing pigment dispersion in the erythrophores, leucophores, and melanophores of Uca. In contrast, Procambarus PDH was 4-fold more potent than beta-PDH in eliciting pigment dispersion in the erythrophores of Procambarus. These peptides displayed less marked differences in potency in triggering leucophore pigment dispersion and light-adaptational distal eye pigment movement in Procambarus. These findings indicate that the structural requirements for PDH-receptor interactions vary with the species and with the target cell type within a given species.

Amino Acid Sequence↗
PubMed1991

Hypopituitarism following snake bite.

A patient who developed hypopituitarism after viperine envenomation is described. Thrombosis as a part of disseminated intravascular coagulation may have been the cause. Hypopituitarism should be suspected in such cases especially when there is associated acute renal failure.

Adult↗
PubMed1991

Response of Ehrlich carcinoma and the small intestine of mouse to combined treatment with chlorpromazine and X-rays.

The effect of combined treatment with chlorpromazine (20 mg/kg body weight) and X-rays at different dose levels was tested on the growth of Ehrlich carcinoma tumor in solid or ascites form in mice. The radiation response of murine gut was also examined separately but under similar experimental conditions. The results obtained indicate that chlorpromazine did not influence the radiation response of all the test systems used in this study. The relevant literature, reviewed in short, shows that the interaction between chlorpromazine and X-rays can result in enhanced radiation response, non-interference or increased radiation tolerance. Therefore any combined effect of chlorpromazine and X-rays observed cannot be generalised.

Animals↗
PubMed1990

Crystallization of a calcium-binding lysozyme from horse milk.

Crystals of the calcium-containing lysozyme from horse milk have been grown by precipitation with sodium phosphate. The crystals are orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 53.2, b = 57.1, and c = 38.2 A and contain a single molecule in the asymmetric unit. The crystals are suitable for high resolution x-ray structural analysis.

Amino Acid Sequence↗
PubMed1990

Isolation and identification of a peptide from rat brain which inhibits [3H]TCP binding.

1. A stereospecific radioreceptor binding assay for the phencyclidine analogue [3H]TCP was utilized to screen for inhibitors of binding in extracts of rat brain. 2. Extracts were prepared from rat cortex and hippocampus by methods employing aqueous acid or acidified methanol. Samples were fractionated by reversed phase-HPLC (RP-HPLC) and tested for activity in the radioreceptor assay. Three zones of activity were detected. The most active fraction was further purified by high performance-size exclusion chromatography. 3. Size exclusion chromatography revealed two zones of activity, corresponding to mol. wts of 4000-8000 Da and 1000-2000 Da. Final purification of the lower molecular weight material was achieved by RP-HPLC. 4. Two well-separated peaks were shown to be homogeneous. Their amino acid sequences were determined by automated Edman degradation and data base searching identified these two peaks as the undecapeptide Substance P and its oxidized counterpart (Substance P sulfoxide). 5. Comparative HPLC of synthetic Substance P, or its sulfoxide, as well as spectral analysis confirmed the identity of the isolated peptides. 6. Synthetic Substance P inhibits specific [3H]TCP binding in the radioreceptor assay.

Amino Acid Sequence↗
PubMed1990

Response of murine small intestine to combined treatment with fostriecin and X rays.

This radiobiological investigation was based on the measurements of crypt cell survival in mouse small intestine when the animals were injected with a single dose of fostriecin or streptomycin, and subsequently irradiated to the whole body with graded doses of X rays. The experimental data obtained indicated that fostriecin decreased the isoeffect dose to murine intestine by a factor of 2.3, whereas streptomycin did not influence the radiation response. The biological effects of fostriecin on various tumour cell systems in vitro and in vivo are briefly reviewed. The possible basic mechanisms involved in the radiosensitizing action of fostriecin and the implications of these results in the radiation protection of normal tissues are discussed.

Alkenes↗
PubMed1990

Histological and functional correlation of thyroid carcinoma by immunohistochemistry.

40 cases of thyroid carcinoma comprising of 22 follicular, 11 papillary, 4 medullary, 2 anaplastic and 1 medullary carcinoma with focal areas of papillary differentiation were selected for this immunohistochemical study for the presence of thyroglobulin, calcitonin and somatostatin. As per the functional classification recommended by Otto L Jungberg, 22 cases were well differentiated, 13 were of intermediate differentiation with 3 poorly differentiated cases. 2 cases of anaplastic carcinoma were negative for all the 3 markers. Correlation between functional classification and histological pattern show 77% of the well differentiated type to be of follicular pattern with the rest consisting of papillary carcinoma. In the intermediate type 38.4% were follicular carcinoma, 15.3% medullary carcinoma and the rest, papillary carcinoma. Poorly differentiated type consisted of 2 medullary carcinomas. Contrary to previous reports, functional differentiation did not always correlate with histological pattern.

Adenocarcinoma↗
PubMed1989

Long-term experience with 1 per cent topical silver sulphadiazine cream in the management of burn wounds.

Three hundred and forty-two patients with 10-50 per cent body surface area burns were studied prospectively over the 5-year period from 1982 to 1986 for the effectiveness of topical 1 per cent silver sulphadiazine. Various parameters were studied including: (i) healing time of deep partial skin thickness burns, (ii) eschar separation time, (iii) conversion rate of deep dermal burns to full skin thickness burns, (iv) burn wound surface bacterial flora and their changing pattern over the years, (v) incidence of invasive sepsis and (vi) overall mortality. There was a remarkable decrease in the time taken for the healing of deep dermal burns, and the conversion rate of deep dermal burns to full skin thickness was significantly reduced. Eschar separation was delayed considerably. There was a total change in the predominent surface micro-organisms from Staph. aureus, which was predominant in 1982, to pseudomonas species and klebsiella in 1986. Moreover, there was the emergence of a new variety of micro-organism within the last 2 years. The incidence of invasive infection and overall mortality was significantly reduced.

Administration, Topical↗
PubMed1979

Effect of negative pions, relative to 140 kV -- 29 MeV photons and 20 MeV electrons, on proliferation of Ehrlich ascites carcinoma cells.

The effect of negative pions (peak and plateau), photons (140 kV and 29 MeV), and 20 MeV electrons on the proliferative capacity of Ehrlich ascites carcinoma cells was investigated. Proliferative survival curves plotted for the modalities employed are presented. Under the experimental conditions used, the peak pions were more effective than plateau pions by a factor of about 1.4. For 50% survival, 140 kV X-rays had the same effect as peak pions but the latter was more effective (factor 1.2) at 10% survival level. When 140 kV X-rays were taken as the standard, following are the RBE values calculated as 50% survival level: plateau pions --0.73; peak pions --about 1.0; 29 MeV photons --0.73 and 20 MeV electrons --0.6. The results obtained are compared with those reported on other tumor systems and biological test objects.

Animals↗