PubMed Health⌕ Search

Biomedical subjects

L Devi

Publications and source records attributed to L Devi.

35 records · Page 2Linked to original sources
PubMed1992

Secretion and regulation of a neuropeptide-processing enzyme by AtT-20 cells.

The mouse anterior pituitary-derived cell line AtT-20 has been widely used to study the biosynthesis and secretion of peptide hormones, such as ACTH, and peptide-processing enzymes, such as carboxypeptidase-E (CPE). Although AtT-20 cells do not express dynorphin (Dyn), previous studies using gene transfer have revealed that these cells are capable of processing pro-Dyn into peptides such as Dyn-B-13. A Dyn-converting enzyme (DCE) has been identified in AtT-20 cells; this enzyme processes Dyn-B-29 to Dyn-B-13. By several criteria, the enzyme activity secreted from AtT-20 cells is similar to the previously characterized enzyme activity in rat brain and bovine pituitary. In AtT-20 cells, the DCE activity and CPE activity are localized to a similar secretory compartment. Upon stimulation with a beta-adrenergic agonist, a phorbol ester, a calcium ionophore, or forskolin, the secretion of DCE activity was increased; this rise was parallel to the secretion of CPE activity and ACTH. These data suggest that DCE activity is in the regulated pathway of secretion. In AtT-20 cells treated with glucocorticoid for up to 7 days, cellular levels of beta-endorphin decreased to half the control levels. In contrast, the levels of DCE activity did not decline in response to this treatment, suggesting that the enzyme activity was not coregulated with the endogenous hormone. Taken together, the data presented here support a role for DCE in posttranslational processing of regulatory peptides.

Adrenocorticotropic Hormone↗
PubMed1992

Dietary modulators of lipid metabolism in the Indian diet-heart study (I.D.H.S.).

Of the 621 adults (25 to 65 years of age, 531 males) with either risk factors or with coronary heart disease (CHD) 310 subjects were given a cardiovasoprotective (CVP) diet (group A) and 311 subjects a normal diet (group B) in a randomized, single blind and controlled fashion. Risk factors and incidence of CHD were comparable between the two groups. The intervention group received a significantly higher percentage of calories in relation to complex carbohydrates, vegetable proteins, polyunsaturated fatty acids and high P:S ratio diet as compared to the control group. The control group received higher saturated fat and cholesterol. Compliance was assessed by dietary questionnaire during the follow-up. After 8 weeks of dietary trial, there was a significant decrease in mean serum total cholesterol (8.2 vs 2.1%), low density lipoprotein (LDL) cholesterol (9.8 vs. 2.7%) and triglyceride (11.2 vs 5.8%) in the intervention group compared to baseline levels and changes in control subjects. Body weight and physical activity at the entry to study and during the trial were similar in both groups. The decrease in mean HDL cholesterol were insignificant both in the intervention (4.3%) and control group (5.0%). There were no adverse effects of diet during the 8 weeks of trial. It is possible that a diet with 27.5% energy from total fat including 10.1% energy from monounsaturated fatty acids, P:S ratio 1.38, 120 mg dietary cholesterol, 26.0 g dietary fibre per 1000 kcal would modulate the lipid metabolism resulting in a significant reduction in serum total cholesterol, LDL cholesterol and triglyceride with no reduction in HDL cholesterol. This diet may be capable of reducing CHD incidence and mortality in the long term Indian diet-heart study (IDHS).

Adult↗
PubMed1991

Consensus sequence for processing of peptide precursors at monobasic sites.

Many regulatory peptide precursors undergo post-translational processing at mono- and/or dibasic residues. Comparison of amino acids around the monobasic cleavage sites suggests that these cleavages follow certain sequence motifs and can be described as the rules that govern monobasic cleavages: (i) a basic amino acid is present at either 3, 5, or 7 amino acids N-terminal to the cleavage site, (ii) hydrophobic aliphatic amino acids (leucine, isoleucine, valine, or methionine) are never present in the position C-terminal to the monobasic amino acid at the cleavage site, (iii) a cysteine is never present in the vicinity of the cleavage site, and (iv) an aromatic amino acid is never present at the position N-terminal to the monobasic amino acid at the cleavage site. In addition to these rules, the monobasic cleavages follow certain tendencies: (i) the amino acid at the cleavage site tends to be predominantly arginine, (ii) the amino acid at the position C-terminal to the cleavage site tends to be serine, alanine or glycine in more than 60% of the cases, (iii) the amino acid at either 3, 5, or 7 position N-terminal to the cleavage site tends to be arginine, (iv) aromatic amino acids are rare at the position C-terminal to the monobasic amino acid at the cleavage site, and (v) aliphatic amino acids tend to be in the two positions N-terminal to and the two positions C-terminal to the cleavage site, except as noted above. When compared with a large number of sequences containing single basic amino acids, these rules and tendencies are capable of not only correctly predicting the processing sites, but also are capable of excluding most of the single basic sequences that are known to be uncleaved. Many of these rules can also be applied to correctly predict the dibasic and multibasic cleavage sites suggesting that the rules and tendencies could govern endoproteolytic processing at the monobasic, dibasic and multibasic sites.

Amino Acid Sequence↗
PubMed1991

Does dietary magnesium modulate blood lipids?

In a randomized, single-blind, controlled study (400 patients aged 25-63 yr; 374 males, 26 females), 206 subjects were administered a magnesium-rich diet, and 194 subjects their usual diet, for 6 wk. Age, sex, body weight, hypertension, hyperlipidemia, smoking, obesity, diuretic therapy, and diabetes were comparable between the two groups, as were laboratory data at entry to the study. Intervention-group A received a significantly higher amount of dietary magnesium and potassium compared to group B, which received its usual diet. After 6 wk, there was a significant fall in total serum cholesterol (228.5 +/- 46.2 mg/dL), LDL cholesterol 146.5 +/- 75.5 mg/dL), and triglyceride (143.8 +/- 40.5 mg/dL) in group A compared to serum cholesterol (242.5 +/- 58.2 mg/dL), LDL cholesterol (157.0 +/- 78.4 mg/dL), and triglyceride (156.5 +/- 60.0 mg/dL) at entry to study, but no such changes in group-B subjects. HDL cholesterol showed a marginal mean decrease of 0.8 mg/dL in group B and a 2.5 mg/dL increase in group A. The changes in blood lipids were consistent with an increased intake of magnesium and with a rise in serum levels. Although a general blood-lipid-reducing effect of such a diet cannot be excluded, it is possible that dietary magnesium may have contributed to the reduction of total serum cholesterol, LDL cholesterol, and triglyceride, and the marginal rise in HDL cholesterol. More studies with longer follow-up periods are needed to confirm this observation.

Adult↗
PubMed1991

Subcellular localization, partial purification, and characterization of a dynorphin processing endopeptidase from bovine pituitary.

An enzyme capable of cleaving dynorphin B-29 to dynorphin B-13 is present in bovine pituitary, with 40- to 50-fold higher specific activity in the posterior and intermediate lobes than in the anterior lobe. Subcellular fractionation of bovine neurointermediate pituitary shows that this enzyme is present in the peptide-containing secretory vesicles. The enzyme has been purified 2,800-fold from whole bovine pituitaries using ion-exchange and gel filtration chromatography. Purified dynorphin-converting enzyme has a neutral pH optimum, and is subsantially inhibited by the thiol-protease inhibitor p-chloromercuriphenylsulfonic acid, but not by serine or metalloprotease inhibitors. The purified enzyme processes dynorphin B-29 at Arg14, producing both dynorphin B-14 and dynorphin B-13 in a 5:1 ratio. No other cleavages are observed, suggesting that the activity is free from other proteases and is specific for single Arg sequences. Purified enzyme also processes dynorphin A-17 at the single Arg cleavage site, generating both dynorphin A-8 and A-9 in a 7:1 ratio. The tissue distribution, subcellular localization, and substrate specificity of this enzyme are consistent with a physiological role in the processing of dynorphin B-29 and dynorphin A-17, and possibly other peptides, at single Arg residues.

4-Chloromercuribenzenesulfonate↗
PubMed1990

Comparison of a spectrophotometric, a fluorometric, and a novel radiometric assay for carboxypeptidase E (EC 3.4.17.10) and other carboxypeptidase B-like enzymes.

Carboxypeptidase E (CPE) is a carboxypeptidase B-like enzyme involved in the biosynthesis of numerous peptide hormones and neurotransmitters. A sensitive assay for CPE and other carboxypeptidase B-like enzymes has been developed using 125I-acetyl-Tyr-Ala-Arg (125I-AcYAR) as the substrate. This peptide is poorly soluble in ethyl acetate whereas the product of carboxypeptidase B-like enzymatic activity (125I-AcYA) can be quantitatively extracted with this solvent, allowing the rapid separation of product from substrate. This radiometric assay can detect less than 1 pg of either CPE or carboxypeptidase B. For CPE, the assay with 125I-AcYAR is approximately 1000 times more sensitive than a fluorescent assay using dansyl-Phe-Ala-Arg (dans-FAR), and 6000 times more sensitive than a spectrophotometric assay using hippuryl-Arg (hipp-R). CPE hydrolyzes the three substrates with Kcat values of 16 s-1 for AcYAR, 13 s-1 for dans-FAR, and 8.5 s-1 for hipp-R. The Km values for CPE with AcYAR (28 microM) and dans-FAR (34 microM) are similar, and are much lower than the Km with hipp-R (400 microM). Thus, the primary reason for the increased sensitivity of the 125I-AcYAR assay over the fluorescent assay is not a result of kinetic differences but is due to the detection limit of iodinated product (10(-15) mol), compared to the fluorescent product (5 x 10(-11) mol). Applications of this rapid and sensitive radiometric assay to detect CPE in cultured cells and in subcellular fractions of the pituitary are described.

Animals↗
PubMed1989

Regulated expression of the prodynorphin gene in the R2C Leydig tumor cell line.

We report here that prodynorphin mRNA and prodynorphin-derived peptides are synthesized in the R2C rat Leydig tumor cell line. The size of the prodynorphin transcript found in these cells (approximately 2200 nucleotides) is identical to that found in the intact testis. R2C cells also contain proteolytically processed prodynorphin-derived peptides. In R2C cells, the endogenous prodynorphin gene and cellular levels of prodynophin-derived peptides are positively regulated by cAMP analogs, while phorbol esters exert a slight negative regulation of the prodynorphin mRNA. Using gene transfer techniques, we have identified a 210-basepair fragment of the rat prodynorphin gene which initiates the transcription of the bacterial reporter molecule, chloramphenicol acetyl transferase. The chimeric fusion gene, when transfected into R2C cells, exhibited the same positive response to cAMP analogs as the endogenous gene. The results suggest that a cAMP regulatory element resides within the cloned rat prodynorphin fragment, and that the element is functionally active in R2C cells.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Expression and posttranslational processing of preprodynorphin complementary DNA in the mouse anterior pituitary cell line AtT-20.

A recombinant plasmid containing the rat prodynorphin cDNA was introduced into the mouse anterior pituitary corticotroph cell line AtT-20. These cells normally express and posttranslationally process proopiomelanocortin, but not prodynorphin. Stable transformants were isolated and analyzed for the expression and processing of prodynorphin. The stably transformed AtT-20 cells that expressed a 1.3-kilobase prodynorphin mRNA also expressed prodynorphin protein and processed it to dynorphin peptides. The peptides included leucine-enkephalin, beta-neoendorphin, dynorphin-A8, and dynorphin-B, as identified by gel filtration and reverse phase HPLC followed by RIA using peptide-specific antisera. These results demonstrate that AtT-20 cells efficiently and accurately process prodynorphin at both dibasic sites and monobasic cleavage sites, indicating that the AtT-20 cells contain enzymes capable of cleaving the precursor not only at dibasic residues but also at monobasic residues. The release of prodynorphin-derived peptides paralleled secretion of endogenous proopiomelanocortin-derived peptides when stimulated by CRF, a natural secretagogue for ACTH.

Amino Acid Sequence↗
PubMed1987

A solution hybridization assay for the quantitation of prodynorphin mRNA.

We have developed a RNA-RNA solution hybridization assay to quantitate the mRNA coding for prodynorphin precursor. This assay is extremely sensitive and highly specific. Using this assay we have measured the prodynorphin mRNA in various brain regions and reproductive tissues of rat. When we compared the distribution of prodynorphin mRNA with the dynorphin related peptides in these tissues, we found a general parallelism and a few noteworthy exceptions.

Animals↗
PubMed1986

Conversion of leumorphin (dynorphin B-29) to dynorphin B and dynorphin B-14 by thiol protease activity.

Dynorphin B (rimorphin) is formed from leumorphin (dynorphin B-29) by the action of a thiol protease from rat brain membranes, in a single step. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. We have observed that in addition to dynorphin B, dynorphin B-14 is formed from dynorphin B-29. Among the various protease inhibitors tested, none except p-chloromercuribenzensulfonic acid inhibited the formation of the two products. Both temperature and pH had similar effects on the formation of dynorphin B-14 and dynorphin B. The inhibitory potencies of adrenocorticotropic hormone, peptide E, and dynorphin A were virtually identical for the formation of the two products. These results suggest that the same enzyme may be responsible for the formation of dynorphin B-14 and dynorphin B.

Adrenocorticotropic Hormone↗
PubMed1985

Neuropeptide processing by single-step cleavage: conversion of leumorphin (dynorphin B-29) to dynorphin B.

Dynorphin B (rimorphin) is formed from dynorphin B-29 (leumorphin) by the action of a thiol protease from rat brain membranes. This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. In isotope dilution experiments we find that the radioactivity from radiolabelled dynorphin B-29, which appears in dynorphin B during incubation with the enzyme preparation, is not diminished by addition of a high concentration of dynorphin B-Arg14. Moreover, in pulse-chase experiments, radioactivity that appeared in dynorphin B-Arg14 did not decrease, nor did the radioactivity in dynorphin B increase, after chasing with a high concentration of non-radioactive dynorphin B-29. These results indicate that although some dynorphin B-Arg14 is formed by the impure enzyme preparation, it is not an intermediate in the conversion of dynorphin B-29 to dynorphin B. Thus the formation of dynorphin B does not involve the action of a trypsin-like enzyme followed by removal of arginine-14 by a carboxypeptidase B-like enzyme. It appears that a single enzyme converts dynorphin B-29 to dynorphin B in a single step.

Animals↗
PubMed1984

Dynorphin converting enzyme with unusual specificity from rat brain.

A rat brain membrane extract was shown to convert synthetic dynorphin B-29 ("leumorphin") to dynorphin B [dynorphin B-29-(1-13), "rimorphin"]. This represents a "single arginine cleavage" at Thr-Arg at positions 13 and 14 of the substrate. The product was identified by immunoprecipitation with a highly specific dynorphin B antiserum and by coelution with radiolabeled dynorphin B on reversed-phase high-performance liquid chromatography. The converting activity exhibits a pH optimum of 8. It is inhibited by a thiol protease inhibitor but not by inhibitors of cathepsin B or of serine proteases. It is inhibited by dynorphin A but not by various dynorphin A fragments. These results suggest that the converting activity is due to a novel thiol protease distinct from any known protease believed to function in the processing of biologically active peptides.

Animals↗
PubMedDate not supplied

Hysteroplasty and vaginoplasty for reconstruction of the uterus.

A simple surgical procedure for reconstruction of the uterus from available Müllerian bulbs with simultaneous vaginoplasty is described. The Müllerian bulbs on both sides are incised, and suitable central fibromuscular tissue is excised to make a uterine cavity. The margins are sutured around a uterine mold, taking care to leave tubal os free. The reconstructed lower end of the uterus (now representing the cervix and upper third of the vagina) is brought down into the space already made out of the peritoneal septum between the bladder and the rectoanal region. The perineal operation for vaginoplasty is completed after suturing the lower end of the reconstructed uterus to the upper margin of the reconstructed vagina. The vaginal and uterine molds are kept in place for one and two weeks postoperatively, respectively.

Female↗
PubMedDate not supplied

Socioeconomic factors and cesarean section in Manipur.

There has been a great change in the household duties and social habits by Manipuri women since World War II, particularly in recent years. Those born after the war have virtually abandoned the old duties and habits, which facilitated the labor process, for modern and Western traditions. In the past, there was hardly any health care program during pregnancy. Every woman, irrespective of socioeconomic status, performed all household work herself. The type of dwelling house, its setup and arrangements for its maintenance also influenced the ease of childbirth. An analysis of the effects of socioeconomic changes and the expanded health care program on the incidence of cesarean section is presented.

Cesarean Section↗
PubMedDate not supplied

Opioid and other peptides as inhibitors of leumorphin (dynorphin B-29) converting activity.

A thiolprotease from rat brain membranes was shown to convert synthetic dynorphin B-29 (Dyn B-29, "leumorphin") to the tridecapeptide dynorphin B (Dyn B, "rimorphin"). This represents a "single-arginine cleavage" between threonine-13 and arginine-14 of the substrate. The dynorphin converting activity displayed typical Michaelis-Menten kinetics with an apparent Km for the substrate of 0.58 microM. Surprisingly, a synthetic peptide, Dyn B-29-(9-22), which contains the cleavage site, did not inhibit the activity. Dyn A inhibited the activity competitively with an apparent Ki of 3.7 microM. The converting activity was also inhibited by Dyn A-(6-17) but not by Dyn A-(8-17), suggesting a role of Arg6-Arg7 in the inhibition of converting activity. Bovine adrenal medulla Peptide E inhibited the converting activity substantially whereas metorphamide did not, suggesting the importance of COOH-terminal residues in recognition. Beta-Endorphin was an effective inhibitor of converting activity, and [alpha-N-acetyl]beta-endorphin was not, indicating a crucial role of the free NH2-terminus in recognition by the enzyme. ACTH inhibited the activity competitively with an apparent Ki of 39 nM. The converting activity was also inhibited substantially by ACTH-(1-13) but not by alpha-MSH, again indicating a requirement of the free NH2-terminus for recognition. The above results suggest that the converting enzyme recognizes peptides of the three known opioid gene families.

Adrenocorticotropic Hormone↗