PubMed Health⌕ Search

Biomedical subjects

K Muralidhar

Publications and source records attributed to K Muralidhar.

At least 19 recordsLinked to original sources
PubMed1992

Attenuation of the cardiovascular responses to subcutaneous adrenaline in neurosurgical patients.

In 30 neurosurgical patients after induction of anaesthesia and random pretreatment with i.v. propranolol 1 mg or metoprolol 1 mg, heart rate and mean arterial pressure were measured at 30-s intervals after subcutaneous infiltration of adrenaline 1:200,000. While metoprolol prevented the cardiovascular effects of adrenaline infiltration, propranolol pretreatment was associated with a highly significant increase (P less than 0.01) in mean arterial pressure and a significant decrease (P less than 0.05) in heart rate. These results confirm the potentially serious interaction of propranolol and adrenaline during anaesthesia, and support the use of metoprolol instead, to obtund the cardiovascular effects of adrenaline infiltration.

Adult↗
PubMed1992

Heterogeneity in buffalo lutropin.

Lutropin (LH-1) from water buffaloes has been shown to exhibit microheterogeneity in the N-terminal amino-acid sequence of its alpha-subunit. The beta-subunit did not exhibit such microheterogeneity. Another protocol of purification yielded a preparation of buffalo LH (bu LH-2) different from the buffalo LH-1 in certain physico-chemical properties like ease of dissociation into subunits, sugar composition, isoelectric point, and elution profile on S-200. Data appear to indicate the presence of more than one form of buffalo lutropin.

Animals↗
PubMed1991

Physico-chemical and immunological characteristics of pituitary prolactin from water buffaloes (Bubalus bubalis).

Prolactin (PRL) was purified from freshly frozen pituitary glands of water buffaloes (Bubalus bubalis) by a combination of existing procedures of Ellis and Jiang and Wilhelmi involving serial extraction of different pituitary proteins. The partially purified preparation was further fractionated on DEAE-Sephadex followed by Sephadex G-100 chromatography. This was finally purified on HPLC. This preparation was found to be homogeneous by SDS-PAGE and HPLC and had a single N-terminus amino acid (Threonine). The molecular size was estimated to be 24K +/- 0.5 by SDS-PAGE and approximately 25K by GPC-HPLC. The buffalo PRL gave a dose dependent inhibition curve in a rat liver based radio receptor assay with a potency of 30-35 I.U./mg and also in a partial homologous RIA using 125I-buffalo PRL and rabbit anti-oPRL serum giving a potency of 30 I.U./mg. Metabolic labelling studies using 35SO4(2-) with buffalo pituitary minces showed the incorporation of radioactive sulfate into immunoprecipitable PRL-like material. Physico-chemical characterization of the site of the linkage between sulfate and PRL revealed the presence of Tyr-O-SO4 in bu-PRL. A high affinity monoclonal antibody (MAB) with Ka of 10(10) L/M, belonging to IgG1 isotype, and capable of cross reacting with ovine and bovine PRL was generated. This MAB was conformation specific as reduced and carboxymethylated PRL did not react with it. A homologous RIA system using this MAB has been standardised.

Animals↗
PubMed1990

Studies on buffalo pituitary lutropin (LH): physicochemical and immunological properties.

Physicochemical and immunological properties of buffalo pituitary lutropin (buffalo LH) are reported here. The preparation was shown to be homogeneous by several physicochemical criteria. The molecular weight was found to be 30,000-40,000 by SDS-PAGE, GP-HPLC, and ultracentrifugation analyses. It showed certain interesting features, such as anomalous sedimentation behavior, microheterogeneity due to sugar-linked sulfate, and weak immunogenicity in rabbits. The subunit nature of the hormone has been confirmed. Sugar composition showed similarities as well as differences with LH of other species. Preliminary data on the homologous and heterologous RIAs, using iodinated sheep LH and buffalo LH and the respective antisera, have also been given.

Animals↗
PubMed1990

Tension pneumocephalus following posterior fossa surgery in sitting position. A report of 2 cases.

Tension pneumocephalus is a rare complication of posterior fossa surgery in sitting position. We encountered 2 patients with this complication amongst 60 patients operated during the past 2 years. All 60 patients had some amount of intracranial air at the end of surgery. The causative factors of tension pneumocephalus are briefly reviewed. Prompt recognition of this complication is very important. Diagnosis and management are discussed.

Child, Preschool↗
PubMed1990

Effect of LH-RH on the release of sulfated lutropin: a potential in vitro bioassay for LH-RH.

Sheep pituitary cells prelabelled with radioactive [35S] sulfate (35SO4(2-)) were incubated with different concentrations of LH-RH and the release of LH (lutropin) into the medium was monitored in terms of immunoprecipitable [35S] sulfated LH radioactivity and estimation of LH in the same sample by radioimmunoassay. A dose dependent response was obtained with a maximum of a 16 fold increase in immunoprecipitable 35SO4(2-) -labelled LH radioactivity in the medium which was confirmed by radioimmunoassay. Similar results were also obtained for Buserelin, a well known superactive analogue of LH-RH. However, the half maximal response for Buserelin was obtained at 3-5 nM in comparison to 80.5 nM for LH-RH. After the maximal response to LH-RH as well as Buserelin, a further increase in the concentrations caused a decrease in the release of immunoprecipitable [35S]-sulfate labelled LH into the medium. Differential labelling of stored and newly synthesized LH with radioactive [35S] sulfate and [3H]-labelled leucine revealed that there was a dose dependent increase in the [35S] sulfate labelled LH into the medium whereas the release of [3H]-leucine labelled newly synthesized LH did not show a parallel increase either at different concentrations of LH-RH or at different time intervals. The above observations strongly suggest the possibility of sulfation of LH being the potential signal indicating the storage of LH in sheep pituitary cells. Another important observation in our study was that the dose dependent response of LH-RH in the form of release of [35S]-sulfate labelled LH, which was monitored by immunoprecipitation with specific LH antiserum, can be used in an in vitro bioassay for LH-RH. We believe that a new cheap and sensitive in vitro bioassay could be developed on the basis of this observation.

Animals↗
PubMed1988

Presence of tyrosine-O-sulfate in sheep pituitary prolactin.

When the metabolically obtained 35S-labelled sheep pituitary prolactin-rich fraction was subjected to chemical deglycosylation the radioactivity was retained in the immunoprecipitable prolactin. 35S-labelled prolactin-rich pituitary extract was fractionated on SDS-PAGE and protein was extracted from prolactin positive bands. When the extracted 35S-labelled prolactin was hydrolysed by alkali and then chromatographed on a thin layer of silica, it showed the presence of a radioactive compound which had an Rf value identical to the standard Tyr-O-SO4 synthesized and characterized in our laboratory.

Animals↗
PubMed1987

Are sheep and buffalo prolactins sulfated?

Radioactive sulfate (35SO2-4) has been shown to be incorporated into immunoprecipitable prolactin-like material from incubated minces of sheep and buffalo pituitaries. The 35S-labelled prolactin could be purified by standard procedures. On SDS-PAGE, the 35S-labelled prolactin rich fraction gives two major Coomassie blue bands around 25KDa and these on Western blot analysis gave positive bands. Radioactive [14C]- mannose was also found incorporated into the prolactin like material. The nature of sulphate link to the peptide is not known. It could be sugar-SO4 and/or Tyrosine-SO4.

Animals↗
PubMed1985

Functional relationship of ammonia to DNA, RNA and protein in brain.

The functional significance of the production of ammonia during neuronal activity is not known, although a number of studies are available concerning the mechanism of of ammonia toxicity in brain. Hyperammonemia without behavioural change was induced in experimental rats by i.p. administration of either a single dose of ammonium acetate or 6 doses with an interval of 1 h during the day or one single dose daily for 7 days. No significant change was observed in the content of DNA, RNA and protein in cerebral cortex, cerebellum and brain stem following the administration of a single dose. There was a marked decreased in the content of DNA in all three brain regions after the administration of 6 hourly doses of ammonium acetate. Under these conditions the RNA was found to increase in all three brain regions. A decrease in the content of protein per gram wet weight was observed in cerebral cortex and brain stem while the change in cerebellum was found to be insignificant. However, the content of RNA and protein was found to show a very significant increase when expressed per microgram of DNA for each region under these conditions, indicating an increase in RNA and protein in the cells surviving the toxic damage caused by ammonia. A marked and significant increase in the content of RNA and protein was observed in all three brain regions following the administration of a single dose per day for 7 days. These results are discussed not only with respect to toxic damage to the glial cells by ammonia, but also with respect to the probable effect of ammonia liberated during neuronal activity on inhibition of lysosomal degradation of protein, and on its stimulatory effects of transcriptional and translational activities. The increased RNA and protein under these conditions may be contributing not only in the proliferation of glial cells (Alzheimer Type II cells) but also in the dendritic spinous growth.

Acetates↗
PubMed1983

Incorporation of radioactive 35SO4(2-) into immunoreactive pituitary lutropin.

The terminal hexosamines of bovine pituitary lutropin are thought to contain a sulfate moiety. In order to test this, a biosynthetic approach was adopted. When rat and buffalo (bovine) pituitaries were incubated with radioactive 35SO4(2-) for 2 h in vitro it was observed that radioactivity test incorporated into trichloroacetic acid-precipitable proteins. When the radioactive proteins were treated with an anti-sheep lutropin serum, radioactivity was found in the immunoprecipitate. The incorporation into rat lutropin like material was very marginal while it was very significant in the case of buffalo lutropin.

Animals↗
PubMed1979

Ability of human chorionic gonadotropin beta-subunit to inhibit the steroidogenic response to lutropin.

Ability of the beta-subunit of human chorionic gonadotropin to inhibit the response to lutropin (luteinizing hormone, LH) was tested in the immature rat ovarian system and pregnant-mare-serum-gonadotropin-primed rat ovarian system with progesterone production being used as the response. Human chorionic gonadotropin beta-subunit was found to inhibit human and ovine lutropin-stimulated progesterone production. At a constant dose of lutropin, inhibition was dependent on the concentration of beta-subunit. When concentration of the beta-subunit was kept constant at 5.0 microgram/ml and the concentration of lutropin was varied, the inhibition was maximum at the saturating concentration of the native hormone. The alpha-subunit of the human chorionic gonadotropin did not inhibit the response to lutropin. The lutropin/beta-subunit ratio required to produce an inhibition of response was much lower than that required to bring about an observable inhibition of binding.

Animals↗
PubMed1978

Effect of human chorionic gonadotrophin and ovine luteinizing hormone on rat ovarian macromolecular metabolism.

Administration of human chorionic gonadotrophin (HCG) or ovine LH to immature rats primed with pregnant mare serum gonadotrophin (PMSG) stimulated the rate of synthesis of polyadenylic acid (poly A)-rich RNA in the ovaries. The rate of total RNA synthesis was not affected significantly by hormone treatment, whereas protein synthesis was enhanced. The increase in the rate of synthesis of poly(A)-rich RNA in the ovaries could be inferred as induction of messenger RNA synthesis after the hormone treatment. The poly(A)-rich nature of the isolated RNA was established by oligo(dT)-cellulose chromatography, binding the Millipore filter disks and hydridization with [3H]polyuridylic acid. The level of cyclic AMP in the ovaries of such rats was also raised after administration of LH, the increase coincided with the increase in the rate of synthesis of poly(A)-rich RNA. The implications of these results are discussed in the light of the biochemical basis of luteinization and the action of LH.

Animals↗