Molecular structure of a major insulin/mitogen-activated 70-kDa S6 protein kinase

The molecular structure of a rat hepatoma 70-kDa insulin/mitogen-stimulated S6 protein kinase, obtained by molecular cloning, is compared to that of a rat homolog of the 85-kDa Xenopus S6 protein kinase alpha; both kinases were cloned from H4 hepatoma cDNA libraries. The 70-kDa S6 kinase (calculated molecular mass of 59,186 Da) exhibits a single catalytic domain that is most closely related in amino acid sequence (56% identity) to the amino-terminal, kinase C-like domain of the rat p85 S6 kinase (calculated molecular mass of 82,695 Da); strong similarity extends through a further 67 residues carboxyl-terminal to the catalytic domain (40% identity), corresponding to a region also conserved among the kinase C family. Outside of this segment of approximately 330 amino acids, the structures of the p70 and p85 S6 kinases diverge substantially. The p70 S6 kinase is known to be activated through serine/threonine phosphorylation by unidentified insulin/mitogen-activated protein kinases. A model for the regulation of p70 S6 protein kinase activity is proposed wherein the low activity of the unphosphorylated enzyme results from the binding of a basic, inhibitory pseudosubstrate site (located carboxyl-terminal to the extended catalytic domain) to an acidic substrate binding region (located amino-terminal to the catalytic domain); substrate binding is thereby prevented. S6 kinase activation requires displacement of this inhibitory segment, which is proposed to occur consequent to its multiple phosphorylation. The putative autoinhibitory segment contains several serine and threonine residues, each followed directly by a proline residue. This motif may prevent autophosphorylation but permit transphosphorylation; two of these serine residues reside in a maturation promoting factor (MPF)/cdc-2 consensus motif. Thus, hormonal regulation of S6 kinase may involve the action of MPF/cdc-2 or protein kinases with related substrate specificity.

Asymmetric extraction of membrane lipids by CHAPS

We have characterized and quantitated the lipids which are cosolubilized with serotonin 5-HT1A sites from sheep brain using 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Dialysis of the CHAPS extract produced a [3H]8-hydroxy(2-di-n-propylamino)tetralin [( 3H]8-OH-DPAT) binding vesicular preparation of the protein. Quantitative analysis of the lipids present in the CHAPS extract by HPTLC and transmittance-densitometry revealed extraction of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidyl serine (PS) and phosphatidic acid (PA) in striking preference over cholesterol, galactosylceramides, sulfatides and sphingomyelin. All lipids present in the clear CHAPS-extract were coeluted with the [3H]8-OH-DPAT binding preparation were separated by centrifugation, 95-100% of the [3H]8-OH-DPAT binding protein was retained in the vesicle-containing pellet. The supernatant contained small amounts of cholesterol, PE and PC, but virtually no PS, PI, or PA, whereas the vesicular pellet contained all the lipids mentioned, indicating that PS, PI and PA are more tightly bound to the vesicles than PE, PC and cholesterol. SDS-PAGE analysis of the pellet revealed two major protein bands, at 58 kDa and 33.5 kDa, respectively. Our report outlines a simple and improved densitometric assay used for the first detailed analysis of lipids cosolubilized with an active, membrane protein, and also, a simple assay for CHAPS.

Anticoagulant therapy in acute myocardial infarction

In 265 patients of acute myocardial infarction (AMI) heparin followed by warfarin sodium was used routinely whenever there was no contraindication to the drug. Patients were followed up to 2 years with weekly estimation of prothrombin time. Another 265 patients of AMI having identical clinical profiles were taken as control and neither any anticoagulant nor any antiplatelet agent was used in them. Both groups were also treated with identical coronary dilators whenever needed. 2 years cardiac mortality was 11.6% in the control group and 5.9% in the anticoagulant therapy (ACT) recipient group (P less than 0.05). Incidence of reinfarction (RMI) was 14.4% during the period in the control group whereas it was only 6.7% in the ACT group (P less than 0.05). The incidence of intracranial events were also more frequent in control group (8.4%) compared to ACT group (3.1%) (P less than 0.05). However on further analysis of intracranial events, it was found that haemorrhagic intracranial events were slightly more frequent in ACT (2.3%) than in the control group (2%), but this difference was statistically insignificant (P greater than 0.05); non-haemorrhagic intracranial events were however significantly less in ACT group (1.96%) compared to the control group (6%) (P less than 0.05). There was no major or fatal extracranial haemorrhagic complication in either group. Only minor extracranial haemorrhages were more commonly observed in the ACT group (4.3%) compared to the control group (1.2%) (P less than 0.05).

Critical evaluation of conventional abdominal closure with single-layer closure in adult and elderly

Two different techniques of abdominal closure, conventional and single-layer, were studied on comparative basis in 55 cases each. Single-layer closure was found to have definite advantage over conventional closure as regards operating or healing time, feasibility, ease and postoperative morbidity. Single-layer closure took 8-10 minutes in comparison to 18-20 minutes required by conventional method. Incidence of burst abdomen was found to be 3.6% in the former and 7.27% in the latter. In only one case of conventional closure incisional hernia occurred whereas none occurred in case of single-layer closure. Moreover complications of scar and delayed healing were less in single-layer closure.

Solubilized glycosyltransferases and biosynthesis in vitro of glycolipids

The assembly of most of the ceramide-linked glycolipids (GSLs) in eukaryotic cells occurs in Golgi bodies. At least 18 different glycolipid:glycosyltransferases (GSL:GLTs) have been characterized, 10 of which have been solubilized. These GLTs can be classified into 2 distinct groups: 1) GLTs dedicated to either Dol-P-P-sugar(s) or ceramide-linked sugar(s); and 2) GLTs with dual loyalties (i.e., they compete with glycolipid- and glycoprotein-bound oligosaccharides). Studies with solubilized and purified GalNAcT-1 and GalNAcT-2 from embryonic chicken brains prove that GalNAcT-1 (UDP-GalNAc:GM3 beta 1-4GalNAcT) is specific for GSL, whereas GalNAcT-2 (UDP-GalNAc:Gb3 beta 1-3GalNAcT) can transfer to an oligosaccharide containing the alpha-linked terminal galactose. Similarly, GalT-3 (UDP-Gal:GM2 beta 1-3GalT) is more specific for ganglio-oligosaccharide and GalT-4 (UDP-Gal:Lc3 beta 1-4GalT) can transfer galactose to N-acetylglucosamine linked to p-nitrophenol, glycolipid or glycoprotein. Both GalT-3 and GalT-4 have been separated and purified from embryonic chicken brains. Studies with solubilized SAT-4 and SAT-3, from bovine spleen and embryonic chicken brains, respectively, suggest the existence of 2 different gene-expressed alpha 2-3SATs. The newly discovered FucT-3 (GDP-Fuc:NeuGc-iLc6-alpha 1-3FucT) from human colon carcinoma (Colo-205) has also been solubilized and separated from other GSL:GLTs. Using a new activity gel-Western blot combined technique, the molecular mass of this FucT-3 was determined to be 105 kDa.

In search of a super solution: controlled trial of glycine-glucose oral rehydration solution in infantile diarrhoea

In a double blind trial a glycine fortified oral glucose electrolyte solution was evaluated in a group of infants and small children (n=25) with moderate to severe dehydration due to acute diarrhoea, and was compared with a matched control group (n=26) receiving only glucose based oral rehydration solution. It is seen that the diarrhoea stool output, duration of diarrhoea, and volume of oral rehydration fluid required to achieve and maintain hydration are significantly lower in the group receiving glycine fortified glucose electrolyte solution. The possibility of developing an oral rehydration solution which could also act as an absorption promoting drug is discussed.

Ovarian steroids and modulation of morphine-induced analgesia and catalepsy in female rats

The influence of ovarian steroids on modulation of antinociceptive and cataleptic responses to morphine in female rats was evaluated. The sensitivity of the animals to morphine varied at different stages of the estrous cycle. The responses of postpartum and ovariectomized rats to morphine was attenuated. The test doses of estradiol-17 beta or progesterone, either alone or in combination, did not alter this attenuated morphine sensitivity. Testosterone, however, sensitized post-partum as well as ovariectomized rats to morphine. Unlike progesterone, 17-alpha-hydroxy progesterone antagonized testosterone. Collectively these data implicate ovarian testosterone as a physiological modulator of actions of morphine in female rats.

Is oral rice electrolyte solution superior to glucose electrolyte solution in infantile diarrhoea?

In a controlled trial of oral rehydration therapy, a rice-based electrolyte solution was evaluated in a group (n=26) of infants and young children aged between 3 months and 5 years with moderate to severe dehydration owing to acute diarrhoea, and the results were compared with a matched control group (n=26) receiving WHO recommended glucose electrolyte solution. The former was found to be more effective than the latter as shown by an appreciably lower rate of stool output, a shorter duration of diarrhoea, and a smaller intake of rehydration fluid.

Antimicrobial, insect sterilizing and ovicidal activity of some oxo-vanadium(IV) and oxo-vanadium(V) complexes

Twenty-three newly synthesized mixed-ligand complexes of oxo-vanadium(IV) and oxo-vanadium(V) were studied for antimicrobial activity. Eight of these complexes were found to have microbicidal properties. The complexes [NH4][VO(gl)2]H2O (gl-H2 = glycolic acid) and [VO(ACOAP)(acac-H)]H20 (ACOAP-H2=Schiff base of acetylacetone and orthoaminophenol, acac-H=acetyl-acetone) show broad bactericidal spectra, while the complexes [VO(ACSAM)2]OH (ACSAM-H = Schiff base of acetylacetone and sulphanilamide) and [VO(CSSAM-H)2]H2O (CSSAM-H =Schiff base of 3-carboxy salicylaldehyde and sulphanilamide) possess pronounced antidermatophytic properties. The latter is inhibitory to plant pathogenic fungi as well. Plant tumour producing Agrobacterium tumefaciens is effectively inhibited in vitro by the complex [VO(ACTSC-Na)(acac)]H2O (ACTSC-H2 = condensation product of acetylacetone and thiosemicarbazide). Minimum inhibitory concentrations of all the active complexes are within the values of 0.125-2.00 mg/ml. Out of the 7 active complexes tested for 50% inhibition of conidial germination of Helminthosporium oryzae, a rice plant pathogen, only 1 complex, viz. [VO(acac) (ACACAACD)] (ACACAACD(H)NH4 equal Schiff base of acetylacetone and ammonium 2-amino-1-cyclopentene-1-dithiocarboxylate) shows a positive result. The effective concentration is 0.55 mg/ml. Three vanadium complexes were tested for insect sterilant and ovicidal properties on the red cotton bug, Dysdercus koenigi. The complex [VO(HASA-Na) (acac)]H2O (HASA-H2 = Schiff base of orthohydroxyacetophenone and anthr anilic acid) was found to be a suitable male sterilant.

Can acetate replace bicarbonate in oral rehydration solution for infantile diarrhoea?

In a double-blind trial two groups of 20 infants and young children suffering from diarrhoeal dehydration and acidosis were successfully treated with an acetate and a bicarbonate containing oral rehydration solution. The former was found to be as effective as the latter and was equally acceptable to the patient.

Possible physiological role of adrenal and gonadal steroids in morphine analgesia

The effects of adrenal and gonadal steroids on the antinociceptive potency of parenteral morphine were studied in male rats. At all doses studied, dexamethasone pretreatment 30 min before morphine sensitized the animals to the effects of parenteral morphine. However, at higher doses of dexamethasone this sensitization was masked when dexamethasone was given 4 h before morphine by a cycloheximide-sensitive attenuating effect. This feature is not a specific glucocorticoid effect since testosterone showed similar characteristics. Estradiol-17beta and progesterone, however, produced only a cycloheximide-sensitive attenuating response at 4 h. Deoxycorticosterone on the contrary had a cycloheximide-independent attenuating influence with both pretreatment schedules. Results of the present study indicate that morphine subsensitivity after castration or supersensitivity after adrenalectomy may be attributed to the relative lack of testosterone or mineralocorticoid in the respective conditions. Furthermore, in view of the fact that testosterone plays a rate-limiting role in determining the morphine sensitivity of the animals and that mineralocorticoids exert their effects indirectly via antagonism of testosterone action.

Antimicrobial, insect sterilizing and ovicidal activity of some cobalt(II) and cobalt(III) complexes

Twenty-one mixed-ligand complexes of cobalt(II) and cobalt(III) have been screened for their antimicrobial, insect sterilizing and ovicidal activities. Three of these cobalt(III) complexes exhibit broad antimicrobial spectra, including against human bacterial pathogens, dermatophytes and plant pathogenic fungi, while one exhibits feeble activity against a human pathogenic bacterium. These results have been compared with the activity of the corresponding cobalt(II) complexes, which have been found to be inactive, while the free ligands show reduced activity compared with the cobalt(III) complexes. Change in biological activity induced by a particular complex appears to be dependent on the composition of the first co-ordination sphere. Two of these complexes showed 50% inhibition of the conidial germination of Helminthosporium oryzae and Alternaria triticina. These results indicate their potential for use against human and plant pathogenic microbes. Minimum inhibitory concentrations of the cobalt(III) complexes were determined. Three of these cobalt(III) complexes have been tested for insect sterilizing and ovicidal activities on Dysdercus koenigi F. Positive sterilizing and ovicidal actions of [Co(BSOP)(NH3)2]NO3 (where BSOP-H2 is the Schiff base derived from salicylaldehyde and orthophenylene-diamine) were obtained. Possible mechanism(s) of all these activities are discussed qualitatively.

Characterization of the beta-adrenergic receptor mediating secretion of parathyroid hormone

In vitro incubation studies with bovine parathyroid gland slices compared the relative responsiveness of parathyroid hormone (PTH) secretion to isoprotherenol, epinephrine or norepinephrine. Isoproterenol was the most potent and norepinephrine the least potent of the three stimuli, suggesting a beta 2 type of an adrenergic response. However in this in vitro system, tazalol, a selective beta 1 adrenergic agonist significantly stimulated PTH secretion, whereas terbutaline, a selective beta 2 agonist had no effect. In addition, practolol, a selective beta 1 adrenergic antagonist blocked isoproterenol- or tazolol-stimulated PTH secretion. In vivo studies in normal human subjects showed that injection of te nonselective beta agonist, isoproterenol, (0.15 mg s.c.) significantly increased, whereas injection of the selective beta 2 agonist, terbulatine (0.3 mg s.c.) had no effect on serum PTH levels. These latter studies with putative selective beta adrenergic agents suggest that the beta adrenergic receptor mediating PTH secretion is of the beta 1 type (in contrast to the studies above with nonselective agents). The studies suggest that the beta adrenergic receptor mediating PTH secretion apparently differs from the classical beta 1 receptor described in th myocardium or the classical beta 2 receptor described in the bronchial smooth muscle.

Role of calcium and beta-adrenergic system in control of parathyroid hormone secretion

In the rat, EDTA and isoproterenol stimulated PTH secretion, whereas high calcium and propranolol inhibited it. The stimulatory effects of EDTA and isoproterenol were still evident and unaltered in the presence of blocks induced by propranolol and high calcium, respectively. The findings suggest that: (i) both calcium and beta-adrenergic stimuli affect PTH secretion; and (ii) the two influences affect the PTH secretion by separate initial pathways.