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Biomedical subjects

R Day

Publications and source records attributed to R Day.

At least 181 records · Page 10Linked to original sources
PubMed1992

Testicular expression of PC4 in the rat: molecular diversity of a novel germ cell-specific Kex2/subtilisin-like proprotein convertase.

The rat cDNA sequence of PC4 (rPC4), representing a new member of the Kex2/subtilisin-like proprotein convertases, demonstrated the presence of at least three rPC4 mRNAs resulting in the production of rPC4-A (654 amino acids), rPC4-B (619 amino acids), and rPC4-C (609 amino acids) with different C-terminal sequences. Analogous to rat PC4, three cDNAs were also found for the mouse PC4. The observed molecular diversity of PC4 mRNA possibly results from the differential splicing and/or exon skipping of the parent gene. PC4 mRNA, with a major form at 2.8 kilobases, was highly abundant in the rat testis but could not be detected by Northern analysis in any other tissues including the central nervous system and peripheral tissues. Testicular cell separation studies combined with Northern analysis indicate the high expression levels of PC4 in germ cells but not in Leydig, Sertoli, or peritubular cells. In situ hybridization histochemistry confirms the site of PC4 gene expression as the pachytene spermatocytes and the round spermatids but not in the elongating spermatids. We also demonstrate the colocalization of PC4 with proenkephalin in testicular germ cells by in situ hybridization. A study of the ontogeny of PC4 indicated that PC4 mRNA was first expressed postnatally between days 19 and 22, coinciding with the first stages of spermiogenesis. The stage-specific expression of PC4 in testis indicates its potential role in the developmental maturation of germ cells and that this convertase may play a specific physiological function in reproduction.

Amino Acid Sequence↗
PubMed1992

Distribution and regulation of the prohormone convertases PC1 and PC2 in the rat pituitary.

PC1 and PC2 are enzymes involved in the activation of prohormones via the cleavage of pairs of basic amino acids. The expression levels of each of these enzymes were evaluated in the rat anterior and neurointermediate pituitary lobes by in situ hybridization and Northern gel analysis and after various pharmacological manipulations. All intermediate lobe melanotrophs expressed high levels of PC2 mRNA and lower levels of PC1 mRNA. PC1 mRNA was highly expressed throughout the anterior lobe; however, appreciable PC2 mRNA levels were also found. Based on colocalization studies, anterior lobe corticotrophs were found to express PC1 mRNA, but very little PC2 mRNA. Neurointermediate lobe levels of PC1, PC2, and POMC mRNA increased 2- to 6-fold in rats treated with haloperidol, while they decreased to 10-25% of their control values after bromocriptine treatment. These results indicate that in the intermediate lobe, dopamine is involved in the regulation of PC1 and PC2. In the anterior lobe, haloperidol had a strong effect on PC2 mRNA, increasing its levels by 8- to 12-fold compared to the control value, while PC1 mRNA was unaffected. Both PC1 and PC2 mRNA levels were increased 5- to 9-fold in animals made hypothyroid by treatment with 6-n-propyl-2-thiouracil. Adrenalectomy had no significant effect on anterior lobe PC1 mRNA levels. However, both PC1 and PC2 mRNA levels were responsive to dexamethasone treatment in the AtT-20 cell lines. Our results indicate that dopamine, thyroid hormones, and corticosteroids are involved in PC1 and/or PC2 gene expression. These data are also consistent with the role of PC1 and PC2 as prohormone-processing enzymes.

Amino Acid Sequence↗
PubMed1992

Leprosy control in 7 districts of south Sulawesi, Indonesia, 1986-91.

This paper describes the leprosy control programme in 7 districts of the South Sulawesi Province in Indonesia. This province is reported to have the highest prevalence of leprosy in the country. The programme started in 1986 with re-registration of all patients on the cumulative registers. Strict criteria for admission of patients to MDT were initially applied. In 1990 it appeared that these criteria had been too strict, thus necessitating a second re-registration of patients still on DDS monotherapy. More flexible criteria for admission to MDT led to an increase in MDT coverage from 45% to 78% within 6 months. By April 1991, 5 years after the start of the programme, the registered prevalence had decreased from 4.4 per 1000 in 1986 to 1.6 per 1000; the coverage with MDT had increased from 6% in 1986 to 78%, and the case detection rate remained stable around 4 per 10,000 after an initial increase at the start of the programme.

Humans↗
PubMed1991

Quinolinic acid elevates striatal and pallidal Met-enkephalin levels: the role of enkephalin synthesis and release.

Huntington's chorea (HC) is characterized, in part, by a substantial deficit in the striatal and pallidal enkephalin levels. Recently, an attempt was made to replicate this deficit by focally injecting quinolinic acid (QUIN), an excitotoxin, into the rat striatum. However, at 7 days post-injection, QUIN produced a dose-related and bilateral increase in the striatal and pallidal levels of met-enkephalin-like immunoreactivity (ME-i.r.), an effect which was attenuated in the presence of excitatory amino acid (EAA) receptor antagonists. In the present study, the action of QUIN was investigated further. To determine whether the QUIN (72 nmol)-induced elevations in ME-i.r. reflected the enhanced synthesis of the peptide, the striatal levels of proenkephalin mRNA were assayed 7 days following a unilateral injection of QUIN into the rat striatum. QUIN significantly depleted (50%) of the proenkephalin mRNA level in the injected, but not the contralateral striatum when compared to that in the saline-injected animals. To determine whether the QUIN-induced increases in ME-i.r. were due to an impaired release of the peptide, the release of ME-i.r. from the striatal or pallidal slices obtained from animals 7 days after a saline- or QUIN-injection, was measured. The 30 mM K(+)-stimulated ME-i.r. release from the saline-injected and contralateral striatum represented an 8-fold increase above the spontaneous release level, while this stimulus induced a 6-fold increase in the ME-i.r. release from both the QUIN-injected and contralateral striatum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

PC1 and PC2 are proprotein convertases capable of cleaving proopiomelanocortin at distinct pairs of basic residues.

A recombinant vaccinia virus vector was used to coexpress the two candidate mouse prohormone convertases, PC1 and PC2, together with mouse proopiomelanocortin (POMC) in the constitutively secreting cell line BSC-40 and in the endocrine tissue-derived cell lines PC12 and AtT-20, which exhibit regulated secretion. Monitoring of POMC processing demonstrated the distinct cleavage specificities of PC1 and PC2, since in the cell lines analyzed (i) PC1 cleaves POMC into corticotropin and beta-lipotropin, (ii) PC2 cleaves POMC into beta-endorphin, an N-terminally extended corticotropin containing the joining peptide, and either alpha MSH or desacetyl-alpha MSH, and (iii) PC2 cleaves POMC at the five pairs of basic residues analyzed, whereas PC1 cleaves two of them preferentially, suggesting that PC2 has a broader spectrum of activity than PC1. These data are consistent with our hypothesis on the physiological role of PC1 and PC2 as distinct proprotein convertases acting alone or together to produce a set of tissue-specific maturation products in the brain and in peripheral tissues.

Amino Acid Sequence↗
PubMed1991

Atypical prodynorphin gene expression in corticosteroid-producing cells of the rat adrenal gland.

Prodynorphin (proDyn) gene expression was examined in the rat adrenal gland. In situ hybridization revealed a heterogenous proDyn mRNA distribution limited almost exclusively to the adrenal cortex; the inner cortical layers contained the highest amounts. In the adrenal medulla, only scattered single cells were seen. By Northern (RNA) blot analysis, adrenocortical proDyn mRNA levels were highly abundant but of smaller size than proDyn transcripts found in the brain. Low levels of the brain-size proDyn mRNA transcript were detected but restricted to the medulla. A discrepancy was suggested when comparing the high abundance of proDyn mRNA levels with the low levels of proDyn-derived peptide in the adrenal. A hypothesis of nontranslation of the shorter proDyn mRNA by adrenocortical cells was rejected because polysomal loading analysis suggests that the mRNA is translated. We propose that adrenocortical proDyn-derived peptides are not targeted for storage but are released shortly after synthesis, thus accounting for low peptide levels. We also measured proDyn mRNA levels in response to stimuli known to affect adrenocortical cells and their most important function--steroidogenesis. Adrenals from hypophysectomized rats had less proDyn mRNA by a factor of 5 than adrenals from normal sham-operated rats. Normal levels were restored by adrenocorticotrophic hormone administration, indicating a potential importance of adrenal proDyn in the hypothalamic-adrenal-pituitary axis.

Adrenal Cortex↗
PubMed1991

Gene amplification and gene dosage in cell lines derived from squamous cell carcinoma of the head and neck.

Gene amplification and related alterations in gene dosage were analyzed in a series of 34 cell lines derived from different human head and neck squamous cell carcinomas (SCCHN). INT2 gene amplification was observed in 62%, MYC gene amplification in 24%, and EGFR gene amplification in 21% of the cell lines. There was a strong correlation between EGFR gene amplification and increased copies of the ERBB2 gene on chromosome 17, suggesting a synergistic selection for these two genes either during cancer progression or in culture. Two abnormalities showed a significant correlation with clinical course: MYC gene amplification showed an inverse correlation with tumor recurrence (r = -0.44, p = 0.01), and a small increase in MYCL gene copies on chromosome I correlated with the presence of metastases (r = 0.61, p = 0.001). This altered MYCL gene dosage might represent a chromosome translocation rather than true gene amplification. In addition to gene amplification, 79% of the cell lines had increased copies of chromosome 8. Comparison of the cell lines with several of the corresponding primary tumors demonstrated that most gene amplifications were already present in the primary tumors, although some appeared de novo in cell culture. These studies indicate that gene amplification, especially of INT2, is a prominent abnormality in head and neck squamous cell cancer. Aneuploidy and chromosomal lesions other than gene amplification were also found to alter the dosage of several oncogenes specifically.

Carcinoma, Squamous Cell↗
PubMed1991

Effect of cold ischemia time on the early outcome of human hepatic allografts preserved with UW solution.

Five hundred ninety-three cadaveric livers were used for primary liver transplantation between October 24, 1987, and May 19, 1989. The grafts were procured with a combined method, using in situ cooling with cold electrolyte solution and backtable flushing with UW solution. The mean cold-ischemia time was 12.8 (range 2.4-34.7) hr. The cases were divided into 5 groups according to the cold-ischemia time: group 1: less than 10 hr (n = 223); group 2: 10-14 hr (n = 188); group 3: 15-19 hr (n = 101); group 4: 20-24 hr (n = 52); and group 5: greater than or equal to 25 hr (n = 29). There was no difference between the 5 groups in 1-year patient survival, highest SGOT in first week after operation, and SGOT and total bilirubin during the first month after operation. However, with a logistic regression model, the retransplantation rate (P = 0.001) and primary nonfunction rate (P = 0.006) significantly rose as cold-ischemia time increased, meaning that the equivalency of patient survival was increasingly dependent on aggressive retransplantation.

Adenosine↗
PubMed1991

The treatment of patients with newly diagnosed poor prognosis acute myelogenous leukaemia: response to treatment and treatment failure.

The failure of poor prognosis patients with newly diagnosed AML to enter remission is usually due to two phenomena: a high mortality rate and resistance of the leukaemia to chemotherapy. We conducted a pilot study of a regimen designed to overcome these two types of treatment failure. Patients were carefully selected for therapy on the basis of their likelihood of surviving. Chemotherapy consisted of high dose cytosine arabinoside (HDaraC) with the doses modified on the basis of patient age so as to reduce the risk of toxicity. Finally, daunorubicin was administered only to those patients for whom HDaraC was not likely to produce sufficient antileukaemia effects to produce a remission. The median patient age was 67 years and 69/88 (78%) patients had a history of preleukaemia and/or toxic exposure. Only 11/84 (13%) patients died during remission induction therapy and 40/84 (48%) entered CR. Patients with only one risk factor had a higher CR rate than those with more than one risk factor (56% v. 30%, P = 0.02) and also had longer durations (222 d v. 113.5 d, P = 0.035). Two types of resistance to chemotherapy were observed: 'classical resistance' (the failure of chemotherapy to produce substantial killing of leukaemia cells) and the rapid regrowth of leukaemia cells subsequent to a level of cytoreduction which otherwise would have been sufficient to produce a CR.

Aged↗
PubMed1991

A mutation in the putative Mg(2+)-binding site of Gs alpha prevents its activation by receptors.

The properties of a Gs alpha mutant with an Asn substituted for Ser at position 54, designated mutant 54Asn alpha s, were studied after expression in S49 alpha s-deficient (cyc-) cells. Ser-54 in alpha s is comparable to Ser-17 in Ras, which is involved in binding Mg2+ associated with bound nucleotide. 54Asn alpha s did not restore either hormone-induced cyclic AMP production in intact cyc- cells or hormone-induced adenylyl cyclase activation in membranes isolated from these cells. The defect was a failure of ligand-bound receptor to activate 54Asn alpha s, since the mutant protein retained the ability to activate adenylyl cyclase in isolated membranes in the presence of GTP or GTP gamma S. Guanine nucleotide regulation of mutant alpha s suggested that it has increased guanine nucleotide exchange rates and an increased preference for diphosphates over triphosphates. Hormone stimulation magnified the preference of 54Asn alpha s for diphosphates, which could account for its inability to be activated by receptor. The properties of this mutant are discussed in terms of similarities to and differences with the analogous RasH mutant, which has been shown to interfere with endogenous Ras function in cells.

Adenylyl Cyclases↗
PubMed1991

Mammalian neural and endocrine pro-protein and pro-hormone convertases belonging to the subtilisin family of serine proteinases.

Conversion of pro-hormones and precursor proteins into biologically active peptides and proteins involves the concerted action of a number of convertases and post-translation modification enzymes. The identification of the yeast convertase kexin as a prototype processing enzyme led to the discovery of the mammalian convertase designated furin, PC1 and PC2. Whereas furin is ubiquitously expressed, PC1 and PC2 are found only in endocrine and neural tissues and cell lines. In man and mouse, the genes coding for furin, PC1 and PC2 reside on three different chromosomes. The analysis of the intracellular processing of PC1 and PC2 and the removal of their pro-segment is presented, together with a summary of the cleavage specificity of these enzymes for precursors such as pro-opiomelanocortin (POMC) and human pro-renin. The distinct tissue distribution of PC1 and PC2 and their coregulation with POMC in the pituitary neurointermediate lobe adds credence to their physiological role as convertases involved in the tissue-specific processing of precursor proteins.

Amino Acid Sequence↗
PubMed1991

Neuroanatomical and functional studies of peptide precursor-processing enzymes.

An overview of in situ hybridization mapping studies comparing the brain distributions of mRNA transcripts encoding the proprotein convertase Furin, PC1 and PC2 in relation to transcripts encoding carboxypeptidase H (CPE) and peptidylglycine alpha-amidating monooxygenase (PAM) is presented. Furin mRNA was detected in both neurons and non-neuronal cells throughout all brain areas. The cellular localization of PC1 and PC2 was primarily neuronal, with PC2 generally more widely distributed, although many regional variations were detected. The detection of specific combinations of the convertases, CPE and PAM in peptide-rich brain regions suggests that specific enzymatic pathways are involved in neuropeptide processing. Results are also described from a series of functional studies on the processing of pro-opiomelanocortin (POMC) in a heterologous neuronal cell line, Neuro-2A, which expresses low levels of PC2 mRNA but no detectable PC1 mRNA. Two contrasting POMC-processing patterns were observed: one where the precursor was processed at a number of cleavage sites to produce several peptides, and another where POMC was processed at a single cleavage site to produce beta E only. If PC2 is responsible for POMC processing in transfected cells, this enzyme may have favored cleavage of the amino terminal-processing site above other sites in the latter type of cell line.

Animals↗
PubMed1991

A model standardized risk assessment protocol for use with hazardous waste sites.

This paper presents a model standardized risk assessment protocol (SRAP) for use with hazardous waste sites. The proposed SRAP focuses on the degree and patterns of evidence that exist for a significant risk to human populations from exposure to a hazardous waste site. The SRAP was designed with at least four specific goals in mind: to organize the available scientific data on a specific site and to highlight important gaps in this knowledge; to facilitate rational, cost-effective decision making about the best distribution of available manpower and resources; to systematically classify sites roughly according to the level of risk they pose to surrounding human populations; and to promote an improved level of communication among professionals working in the area of waste site management and between decision makers and the local population.

Algorithms↗
PubMed1991

One hundred ten consecutive primary orthotopic liver transplants under FK 506 in adults.

An account is given of the 6- to 12-month survival, and causes of failure in 110 consecutive patients who underwent primary liver transplantation under treatment from the outset with FK 506 and steroids. The patient survival is 92.7%, and the first graft survival is 87.3%. At a very high frequency, the patients achieved good graft function, and they had a relatively low morbidity that was partially ascribable to minimal use and early discontinuance (in 60% of cases) of steroids. Renal dysfunction and other adverse findings were largely confined to patients with poor initial graft function and consequent apparent alteration of the kinetics of FK 506 elimination, causing functional overdosage. Results compare very favorably with our past record using conventional immunosuppression, and support the belief that FK 506 is a superior immunosuppressive agent which is suitable for chronic administration.

Adult↗
PubMed1991

Dominant inhibitory Ras mutants demonstrate the requirement for Ras activity in the action of tyrosine kinase oncogenes.

Two inhibitory Ras mutant proteins [(Asn 17) Ras and RAST] were microinjected into NIH3T3 cells in order to compare their inhibitory activity with that of a neutralizing anti-ras antibody. Both mutants were able to block efficiently the mitogenic effects of serum added to quiescent NIH3T3 cells. Furthermore, each of the inhibitors blocked cell cycle progression at the same point as the injected anti-ras antibody, just prior to the initiation of a new round of DNA synthesis. Finally, as with the injected anti-ras antibody, each of the inhibitors was efficiently able to block proliferation and reverse the transformed morphology of cells transformed by tyrosine kinase oncogenes, while cells transformed by serine kinase oncogenes were unaffected. Therefore, results with all three reagents clearly indicate that cellular Ras activity is required in the late G1 phase of the cell cycle and is essential for the maintenance of the transformed phenotype induced by tyrosine but not serine kinase oncogenes. These studies demonstrate the utility of dominant inhibitory mutants as a means of interfering with the activity of cellular oncogenes.

3T3 Cells↗
PubMed1991

NSAIDs, musculoskeletal disorders and gastrointestinal adverse effects.

Paracetamol should be considered as first line treatment for the common painful musculoskeletal disorders, especially osteoarthrosis. NSAIDs, which are beneficial should this fail and inflammation be present, should be prescribed in the lowest dose for the shortest possible time.

Acetaminophen↗