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Biomedical subjects

J S Richards

Publications and source records attributed to J S Richards.

At least 19 recordsLinked to original sources
PubMed1992

Hormonal regulation of messenger ribonucleic acid encoding a novel isoform of prostaglandin endoperoxide H synthase in rat preovulatory follicles. Induction in vivo and in vitro.

Recent purification and amino-terminal analysis of the isoform of prostaglandin endoperoxide H synthase (PGS) induced in rat preovulatory follicles by gonadotropins identified it as a novel distinct isoform of PGS (rPGSi) which exhibited a high degree of homology to the deduced sequence of PGS-related cDNAs recently cloned in chicken and mice. To further verify the similarities of these novel gene products and to examine the hormonal regulation of rPGSi mRNA in ovarian cells, three different in vivo and in vitro models were used. Northern blots using a cDNA encoding the mouse homologue of rPGSi detected a 4.4-kilobase transcript which was rapidly but transiently induced in granulosa cells of preovulatory follicles exposed in vivo to an ovulatory dose of human chorionic gonadotropin. The rPGSi mRNA was undetectable at 0 h, peaked 4 h after human chorionic gonadotropin, and had almost disappeared by 6 h. Increases in rPGSi protein (immunoblots) lagged by about 1 h, peaked at 5 h, and remained present at 11 h. PGSi mRNA and protein were also induced in a time- and dose-dependent manner when preovulatory follicles were isolated and incubated with elevated levels of follicle-stimulating hormone (500 ng/ml) or luteinizing hormone (500 ng/ml), or when differentiated granulosa cell cultures were stimulated with follicle-stimulating hormone, luteinizing hormone, or with gonadotropin-releasing hormone (10(-6) M). In both in vitro systems, rPGSi mRNA peaked at 4-5 h. When the same RNA samples were probed with the mouse cDNA encoding the other PGS isoform, no mRNA transcripts (2.8 kilobases) were observed. These results show for the first time that a rapid and transient induction of mRNA encoding a novel PGS enzyme occurs in granulosa cells of preovulatory follicles prior to ovulation and that results in vitro closely mimicked those in vivo and thereby provide models for studying the molecular mechanisms of rPGSi gene expression.

Animals↗
PubMed1992

Purification and characterization of a novel, distinct isoform of prostaglandin endoperoxide synthase induced by human chorionic gonadotropin in granulosa cells of rat preovulatory follicles.

To purify and characterize the isoform of prostaglandin endoperoxide synthase (rPGSi) induced by human chorionic gonadotropin in granulosa cells of rat preovulatory follicles, solubilized cell extracts were subjected to anionic exchange chromatography, column fractions were resolved by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and rPGSi was visualized by immunoblotting and silver staining techniques. Immunoreactive rPGSi and peroxidase activity co-eluted at pH 6.5 and 6.0. Amino-terminal amino acid sequence of three immunoreactive rPGSi bands (Mr = 72,000, 70,000, and 59,000) were identical, Mr = 59,000 being a proteolytic fragment. Alignment of the amino-terminal sequences of rPGSi with those of ovine PGS (oPGS) indicated that only 15 of 26 residues were identical (58% identity). In contrast, rPGSi was closely related to the deduced amino acid sequence of PGS-related cDNA clones isolated from chicken and mouse cell lines, with 77% (20/26 residues) and 96% (25/26 residues) identity, respectively. Whereas tryptic digests of oPGS generated fragments of Mr = 38,000 and Mr = 33,000, only a small peptide appeared cleaved from the carboxyl terminus of rPGSi. Peroxidase activity of partially purified rPGSi exhibited lower apparent Km and maximal velocity than that of oPGS. Collectively, these results document the existence of a novel rat PGS isoform (based on purification, enzymatic activity, and amino-terminal amino acid sequence) which is hormonally induced and obligatory for a known biological process, ovulation.

Amino Acid Sequence↗
PubMed1992

Retrospective review of sexual and marital satisfaction of spinal cord injury and diabetic males post penile injection or implant.

This study compares sexual activity and sexual and marital satisfaction in spinal-cord-injured (SCI) and diabetic men who had received either a penile prosthesis or papaverine/phentolamine injections for the treatment of impotence. Questionnaires were used retrospectively to assess changes pre- and post-procedure in 30 SCI and 26 diabetic males. Regardless of whether they received a penile prosthesis or injections, both diabetic and SCI males reported increases in diversity and frequency of sexual activities and satisfaction with sexual activities post-implant/injection. When compared with a normative sample, both diabetic and SCI males were found to have poorer body image post-implant/injection. They also reported more disagreement with their partners but engaged in more activities together.

Adult↗
PubMed1992

Enhanced killing of Acanthamoeba cysts in vitro using dimethylsulfoxide.

PURPOSE: Acanthamoeba keratitis is difficult to treat and requires prolonged therapy despite the well-documented in vitro effectiveness of a variety of drugs. The authors propose that this may be due to the cysts formed by the organism in response to hostile conditions. Consequently, the study concentrates on increasing penetration of drugs effective against the parasite into the cysts using dimethylsulfoxide (DMSO). METHODS: The organism is forced to encyst in vitro on solid media by nutrient deprivation. In the first set of experiments, serial dilutions of a standard treatment regimen are applied to the organisms, and these treated cysts are then subcultured onto nutrient-rich material and observed for growth. The experiments are then repeated with DMSO added to the serially diluted standards. In a second set of experiments, the effects of retreatment on a larger concentration of organisms is examined. RESULTS: When applied to a cyst-only population of Acanthamoeba, none of three standard drugs, propamidine isethionate 0.1%, neomycin 1%, or miconazole 1%, was cysticidal. When combined with DMSO 30%, propamidine isethionate was clearly cysticidal even in low dilution. This was confirmed by the retreatment experiments using a larger, standardized cyst population. CONCLUSION: The authors propose that DMSO is acting as a "carrier" for the propamidine isethionate and increases its penetration into the normally drug-resistant cyst form of the organism. Because DMSO has been used topically in the past and shown to be quite safe, this may be a viable new therapy for this difficult condition.

Acanthamoeba↗
PubMed1992

Community reintegration and quality of life following spinal cord injury.

This report contains a brief overview of issues related to community reintegration and quality of life for persons with spinal cord injuries. Current data from the National Spinal Cord Injury Statistical Center are provided on place of residence, employment, education and marital status after rehabilitation discharge. The health policy implications of these data are discussed along with prospects for continued improvement of long term social outcomes and directions for future research.

Employment↗
PubMed1992

Chronic pain and spinal cord injury: review and comment.

The problem of severe chronic pain following spinal cord injury (SCI) has been well delineated for many years. However, progress has been slow in determining which treatment procedures work for which type of SCI pain in a particular individual at a particular time. Reasons for such slow progress include the low incidence and prevalence of SCI making large series of patients unavailable for trials in many centers. Lack of a widely accepted SCI pain classification scheme has also limited the comparability of similar interventions carried out by different investigators. Design limitations of many existing studies that can be remedied in future investigations are reviewed. Finally, discussion of two conceptual models of SCI pain is presented and an argument raised for the utility of both.

Chronic Disease↗
PubMed1992

Induction of prostaglandin H synthase in rat preovulatory follicles by gonadotropin-releasing hormone.

Two distinct isoforms of prostaglandin (PG) endoperoxide synthase (PGS) have been identified in rat ovarian tissues: rPGSi (mol wt, 70,000-72,000) is induced by FSH and LH in preovulatory follicles, whereas the other isoform (mol wt, 69,000) is not. Induction of rPGSi is associated with LH-stimulated increases in PG biosynthesis obligatory for ovulation. Because GnRH, like LH, can also stimulate the synthesis of PGs and ovulation in the rat, this study was undertaken to determine which isoform of PGS might be induced by GnRH, in what cell type, and by what intracellular pathways. Results show that GnRH at relatively low concentrations (10(-8)-10(-7) M) induced the same isoform of PGS (rPGSi) in the same cell type (preovulatory granulosa cells) and within the same 5- to 7-h time course as did LH. Unlike LH and FSH, GnRH did not cause a major increase in cAMP, nor did GnRH induce luteinization. The effects of GnRH on rPGSi in preovulatory follicles were not mimicked by known activators of protein kinase-C (phorbol myristate acetate, bryostatin, diacyglycerol, and (+/-)ionomycin). Epidermal growth factor (but not basic fibroblast growth factor or platelet-derived growth factor), which activates a receptor-associated tyrosine kinase, caused a small increase in rPGSi. Genistein, a selective inhibitor of tyrosine kinases, blocked GnRH and LH induction of rPGSi. Taken together these results suggest that the mechanisms by which GnRH and LH selectively induce rPGSi in granulosa cells of preovulatory follicles before ovulation may converge at some step within a cellular tyrosine kinase cascade. Furthermore, the mechanisms responsible for inducing rPGSi are distinct from those required for cellular luteinization.

Animals↗
PubMed1992

Identification and characterization of the GC-rich and cyclic adenosine 3',5'-monophosphate (cAMP)-inducible promoter of the type II beta cAMP-dependent protein kinase regulatory subunit gene.

A rat genomic clone containing 4.5 kilobases of 5'-flanking DNA and the first exon of the type II beta regulatory subunit (RII beta) of cAMP-dependent protein kinase was isolated, restriction mapped, and sequenced. The proximal 400-basepair promoter region was GC rich, lacked TATA/CAAT box motifs, and initiated transcription at multiple sites. Bandshifting and DNase-I footprinting experiments using this region of the RII beta promoter detected several related specific DNA-protein complexes formed using crude and fractionated nuclear extracts from rat ovary, brain, adrenal gland, and liver. All binding in these experiments mapped to a domain within the same region found to confer cAMP inducibility to a chloramphenicol acetyltransferase (CAT) reporter gene when transfected into primary cultures of rat granulosa cells. Although GC boxes (putative SP1-binding sites) and activator protein-2 (AP-2) elements were present in this functional region, and although expression vectors containing AP-2 sites conferred high levels of cAMP regulation of the CAT gene in cultured ovarian cells, neither the GC boxes nor the AP-2 sites were protected by footprint analyses or required for band shift activity of nuclear extract protein. These known regulatory elements, therefore, may be involved in functional activity of the RII beta promoter, but additional cis-acting DNA and trans-acting factors (yet to be characterized) also appear to interact with the functional promoter of the RII beta gene and regulate the hormone-specific expression of the A-kinase subunit in ovarian and neuronal cells.

Amino Acid Sequence↗
PubMed1992

Cognitive deficits in spinal cord injury: epidemiology and outcome.

Cognitive deficits are common among patients with acute spinal cord injury (SCI), but reported prevalence figures vary because of different methods of study. Factors associated with cognitive deficits in patients with SCI include age, educational background, history of learning disability, chronic alcohol and substance abuse, and concomitant or recurrent traumatic brain injury. Psychologic testing of patients with and without cognitive deficits indicates that impaired psychosocial adjustment and adaptation are more frequent in SCI patients who have evidence of cognitive deficits. Various associations have been found between neuropsychologic test performance and major depression. Cognitive functioning and premorbid educational level appear to be associated with medical stability, the patient's ability to assimilate the necessary skills for survival and adaptation after SCI, and readmission patterns after discharge for initial inpatient rehabilitation.

Brain Injuries↗
PubMed1991

Effects of in vivo dihydrotestosterone treatment on changes in nocturnal surge of prolactin, luteal ultrastructure and P-450scc mRNA and protein content in pregnant rats.

We have demonstrated previously that the administration of dihydrotestosterone (DHT) decreases plasma progesterone levels within 24 h and thus, results in abortion during the first half of pregnancy (Am. J. Physiol. 241 (1981) E444-E448). The purpose of this study was to determine (a) if the administration of DHT suppresses plasma prolactin levels or its nocturnal surge within 24 h after the treatment, (b) how soon after the commencement of treatment do the concentrations of DHT increase and progesterone levels decrease in the circulation, (c) the ultrastructural changes that occur in corpora lutea, and (d) the changes in luteal P-450 side-chain cleavage (P-450scc) enzyme and mRNA content upon DHT treatment. Within 24 h after the commencement of DHT treatment, the nocturnal surge of prolactin, detected in both groups on day 10 at 03.30 h, was inhibited in DHT-treated rats as compared to controls. The non-surge levels of prolactin at 05.00 and 06.00 h were not different between groups. The intraovarian DHT pellet increased plasma levels of the steroid 3-fold within 2 h (blood samples were taken at 2-hourly intervals) when compared to controls. By 24 h DHT levels were decreased but were still higher than controls. Plasma progesterone levels began to fall 6 h after the commencement of treatment. Luteal tissue from animals treated with DHT appeared steroidogenic, and contained more lipid droplets than controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Leiomyosarcoma of the conjunctiva.

The clinical, light microscopic, immunohistologic, and ultrastructural findings of a leiomyosarcoma of the conjunctiva are presented. This tumor was diagnosed after a 26-year history and is the first to be adequately documented as having arisen in the conjunctiva.

Aged↗
PubMed1991

Suicide following spinal cord injury.

A study of 9135 persons injured between 1973 and 1984 and treated at any of 13 model regional spinal cord injury (SCI) care systems was conducted. Follow-up ended December 31, 1985, by which time 50 persons had committed suicide (6.3% of deaths). Based on age-sex-race-specific rates for the general population, 10.2 suicides were expected to occur. Therefore, the standardized mortality ratio (SMR) for suicide was 4.9. The highest SMR occurred 1 to 5 years after injury. The SMR was also elevated for the first post-injury year, but was not significantly elevated after the fifth year. The SMR was significantly elevated for all neurological groups, but was highest for persons with complete paraplegia. The SMR was highest for persons aged 25 to 54 years, but was also elevated for persons aged less than 25 years. Suicide was the leading cause of death for persons with complete paraplegia and the second leading cause of death for persons with incomplete paraplegia. The most common means of committing suicide was by gunshot. These figures demonstrate the need for increased staff, patient and family awareness of this problem, and improved follow-up assessment and psychosocial support programmes.

Adult↗
PubMed1991

Prevention of spinal cord injury: an elementary education approach.

Spinal cord injury (SCI) results in permanent paralysis and most often happens to teenagers and young adults. High risk behaviors are most often the cause; therefore these injuries are often preventable. In response to a gap in existing prevention programs, an elementary age SCI prevention program was developed, designed for implementation by teachers. Evaluation was carried out via a quasi-experimental pre-post comparison group design. Experimental students demonstrated significantly improved knowledge of SCI and its prevention. Similar changes in self-reported safety belt use were not noted. Development of the curriculum, related grant activities, and plans for national dissemination are described.

Child↗
PubMed1991

Changes in rat luteal ultrastructure and P450scc mRNA and protein content after in vivo treatment with a gonadotropin-releasing hormone agonist.

Previous studies have demonstrated that plasma progesterone levels decrease in pregnant rats treated in vivo with a gonadotropin-releasing hormone agonist (GnRH-Ag), without changes in testosterone or estradiol levels in ovarian vein plasma. The objective of this study was to determine the loci of GnRH-Ag disruption of progesterone synthesis by examining luteal mitochondria, lipid droplets, cellular composition, and P450 side-chain cleavage (P450scc) enzyme and mRNA content in the pregnant rat. On Day 7 or 11 of pregnancy, osmotic minipumps containing GnRH-Ag were implanted into 5-7 rats. Sham operations were performed on 5-6 controls at each time period. Five micrograms per day of GnRH-Ag were released for about 24 h, after which corpora lutea and jugular vein plasma were collected. The corpora lutea were prepared for microscopy or analyzed for P450scc enzyme and mRNA content. Plasma progesterone levels were measured by RIA. In those rats treated with GnRH-Ag, progesterone levels had decreased, and within the luteal cells, there was an increase in the number of lipid droplets and a decrease in the number of tubular cristae within the mitochondria. Concomitantly, P450scc enzyme and mRNA content decreased on both Day 8 and Day 12 of pregnancy. Also, GnRH-Ag treatment decreased the ratio of large to small steroidogenic luteal cells on Day 8 of pregnancy, but did not alter cellular ratios on Day 12 of pregnancy. These observations suggest that treatment with GnRH-Ag inhibits progesterone synthesis by decreasing the amount of P450scc mRNA and enzyme content, which may alter the mitochondrial cristae structure on Day 8 and Day 12 of pregnancy. The reduction in tubular cristae and P450scc enzyme in the mitochondria may account for the increase in lipid droplets, as less cholesterol is converted to pregnenolone. An additional mechanism of inhibition may be the reduction in the number of large steroidogenic luteal cells, which appear to be the major source of progesterone in the rat corpus luteum on Day 8 of pregnancy.

Animals↗
PubMed1991

Regulation of cytochrome P450 aromatase messenger ribonucleic acid and activity by steroids and gonadotropins in rat granulosa cells.

Estradiol (E) biosynthesis by the cytochrome P450 aromatase (P450arom) enzyme system increases as preovulatory follicles develop and is subsequently reduced by the ovulatory LH surge. To determine the specific effects of gonadotropins and steroids on expression of P450arom in rat granulosa cells, steady state levels of messenger (m) RNA were examined in vivo and in vitro, with the latter also being related to aromatase enzyme activity and cAMP production. P450arom mRNA and activity were induced in granulosa cells by FSH alone in a dose-, time-, and stage-dependent manner. E enhanced the effects of FSH in vivo and in vitro. The synergistic effect of E with FSH (50 ng/ml) was observed in the absence/presence of serum and was mimicked by a similar concentration (20 nM) of testosterone, dihydrotestosterone, or dexamethasone. In contrast, ovulatory doses of LH (500 ng/ml) or forskolin (10 microM) but not concentrations of progesterone reached in preovulatory follicles (100-1000 nM) acted on differentiated (FSH + E) granulosa cells to cause a rapid loss of P450arom mRNA. Whereas cycloheximide prevented the LH/cAMP-mediated decrease in P450arom mRNA in the differentiated cells, enzyme activity remained unaltered during the same 6-h period. Thus, expression of aromatase mRNA in rat granulosa cells is induced primarily by low FSH/cAMP, enhanced by physiological doses of several steroids (except progesterone), and, once induced, can be rapidly inhibited by elevated gonadotropin/cAMP via a pathway requiring protein synthesis.

Animals↗
PubMed1991

Evidence for two antigenically distinct molecular weight variants of prostaglandin H synthase in the rat ovary.

Two affinity-purified polyclonal antibodies have been generated that differentially recognize two mol wt (Mr) variants of prostaglandin H synthase (PGS) in the rat ovary: antibody-2 recognized PGS of 72,000 Mr (PGS72), and antibody-3 recognized PGS of 69,000 Mr (PGS69). Immunoblot analyses showed that PGS72 was rapidly induced by LH in granulosa cells of preovulatory (PO) follicles and was associated with the increased production of prostaglandins (PGs) obligatory for ovulation. PGS72 was low (negligible) in other ovarian tissues, including PO follicles, corpora lutea, and interstitium. In contrast, PGS69 was constitutively present in small antral and PO follicles (primarily in thecal cells), was unaffected by LH, and was found at higher levels in corpora lutea throughout pregnancy and in the ovarian interstitium. PGS69 (but not PGS72) was also detected by immunoblots in rat adrenal glands, heart, uterus, and kidney. Immunofluorescent localization of PGS72 and PGS69 to ovarian tissue sections confirmed the cell-specific distribution of PGS observed by immunoblot analyses of cell extracts. Immunofluorescent detection of PGS72 required methanol fixation, whereas PGS69 was also observed with paraformaldehyde fixation and Triton X-100 permeabilization, further suggesting biochemical differences in these molecules. Immunoreactive PGS69 in PO follicles, thecal cells, and granulosa cells was associated with low amounts of indomethacin-sensitive production of PGs by these tissues in vitro, which was unaffected by inhibitors of transcription or translation. In contrast, stimulation of PGs in PO follicles by LH in vitro correlated with the marked induction of PGS72, but not PGS69, and was sensitive to both transcriptional and translational inhibitors. Collectively, these studies provide the first evidence that the rat ovary contains two immunologically distinct forms and Mr variants of PGS, each of which is selectively regulated by hormones, localized to specific cell types, differentially sensitive to inhibitors of transcription/translation, and differentially solubilized for immunocytochemical localization.

Animals↗
PubMed1991

Regulation of alpha 2-macroglobulin by luteinizing hormone and prolactin during cell differentiation in the rat ovary.

Alph alpha 2-macroglobulin (alpha 2M), a protease inhibitor which also binds growth factors and cytokines, is temporally expressed in association with remodelling phenomena in the ovary: ovulation and luteinization. Specific hormonal, cellular, subcellular, and molecular events regulating alpha 2M mRNA and protein have been analyzed during follicular growth, ovulation, and luteinization using complementary in vivo and in vitro models. Data demonstrate that alpha 2M mRNA and protein are synthesized in thecal cells of developing follicles in response to low levels of LH. Conversely, alpha 2M mRNA and protein are only synthesized by granulosa cells of follicles that have been stimulated to luteinize either in vivo by the LH surge or in vitro by FSH and testosterone and are also exposed to PRL. The obligatory requirement for PRL is specific; associated with increased numbers of PRL-binding sites; mediated by time-dependent appearance of alpha 2M in the endoplasmic reticulum (12 h), Golgi apparatus (24 h), and secretion vesicles (48 h); and involves in part increased transcription of the alpha 2M gene.

Animals↗