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Biomedical subjects

J L Roberts

Publications and source records attributed to J L Roberts.

At least 37 records · Page 2Linked to original sources
PubMed2000

Lack of efficacy of finasteride in postmenopausal women with androgenetic alopecia.

BACKGROUND: Finasteride, an inhibitor of type 2 5alpha-reductase, decreases serum and scalp dihydrotestosterone (DHT) by inhibiting conversion of testosterone to DHT and has been shown to be effective in men with androgenetic alopecia (AGA). The effects of finasteride in women with AGA have not been evaluated. OBJECTIVE: The purpose of this study was to evaluate the efficacy of finasteride in postmenopausal women with AGA. METHODS: In this 1-year, double-blind, placebo-controlled, randomized, multicenter trial, 137 postmenopausal women (41-60 years of age) with AGA received finasteride 1 mg/day or placebo. Efficacy was evaluated by scalp hair counts, patient and investigator assessments, assessment of global photographs by a blinded expert panel, and histologic analysis of scalp biopsy specimens. RESULTS: After 1 year of therapy, there was no significant difference in the change in hair count between the finasteride and placebo groups. Both treatment groups had significant decreases in hair count in the frontal/parietal (anterior/mid) scalp during the 1-year study period. Similarly, patient, investigator, and photographic assessments as well as scalp biopsy analysis did not demonstrate any improvement in slowing hair thinning, increasing hair growth, or improving the appearance of the hair in finasteride-treated subjects compared with the placebo group. Finasteride was generally well tolerated. CONCLUSION: In postmenopausal women with AGA, finasteride 1 mg/day taken for 12 months did not not increase hair growth or slow the progression of hair thinning.

Administration, Oral↗
PubMed2000

A national study of pressure ulcer prevalence and incidence in acute care hospitals.

OBJECTIVE: This study sought to establish national benchmarks for pressure ulcer prevalence and incidence among acute care health organizations served by Novation LLC. SETTING AND SUBJECTS: One hundred sixteen acute care facilities from 34 states participated; the sample consisted of 17,560 patients in hospital-based medical-surgical or intensive care units. INSTRUMENTS: Standardized education kits were provided to each participating site. The kits included an educational video about pressure ulcer staging, a post-test and answer key, and assessment form for patient data collection. METHODS: Pressure ulcer prevalence was measured during a predetermined 24-hour period at each facility. Incidence was measured over the average length of stay determined for each participating facility. Subjects were assessed by teams consisting of a registered nurse and one other health care professional (e.g. licensed practical nurse, physical therapist). Demographic, wound, and other data were collected for these patients. Data collection forms were audited and submitted to a central site for database entry, analysis, and generation of reports. RESULTS: The average length of stay for the participating facilities was 5 days. Pressure ulcers developed in 7% of the subjects (n = 383); 90% were stage I or II pressure ulcers, and 73% occurred in patients older than 65 years. The most sites based on both prevalence and incidence measurements were the sacrum and coccyx at 26% and 31%, respectively. CONCLUSIONS: Prevalence and incidence studies must be routinely conducted to clearly identify the extent of the pressure ulcer problem to provide guidance for efficient and effective corrective action.

Adult↗
PubMed2000

Estrogen and tamoxifen differentially regulate beta-endorphin and cFos expression and neuronal colocalization in the arcuate nucleus of the rat.

Estrogen regulates hypothalamic gene expression, synthesis and release of the endogenous opioid peptide beta-endorphin (betaEND), although a consensus estrogen response element sequence has not been identified in the rat proopiomelanocortin (POMC) gene. POMC gene expression is also regulated by the activation of AP-1 promoter elements, which are known to be estrogen sensitive. The present studies examine whether estrogen modulates the hypothalamic POMC system through a non-classical mechanism involving AP-1 binding proteins such as cFos. Immunohistochemical double-labeling for betaEND and cFos was used and immunoreactive (-ir) populations were quantified in the arcuate nucleus and periarcuate area across time using unbiased stereological methods. Ovariectomized rats were injected with 50 microg estradiol (E2), 500 microg tamoxifen citrate (TAM) or both (E2+TAM) and were perfused 1, 2, 4 or 48 h later. E2 rapidly increased numbers of cFos-ir, betaEND-ir and doubly-labeled cells after 4 h, and the number of betaEND-ir cells remained high 48 h later, suggesting that the stimulatory effects of cFos on POMC in the hypothalamus persist after the cFos signal decays. Treatment with TAM alone did not affect the numbers of immunoreactive cells, although E2+TAM blocked the E2-mediated induction in all immunoreactive populations. Similar effects were seen at the transcriptional level. E2 increased hypothalamic POMC mRNA after 4 h, while TAM treatment or coadministration of E2+TAM did not significantly change the levels of POMC mRNA. Cellular colocalization of betaEND-ir and cFos-ir supports a possible intracellular co-regulation of these peptides by an estrogen-dependent mechanism within a subset of hypothalamic neurons. It does not, however, appear that E2 acts directly through an AP-1 site within the POMC gene.

Animals↗
PubMed1999

Differential subcellular distribution of neurolysin (EC 3.4.24.16) and thimet oligopeptidase (EC 3.4.24.15) in the rat brain.

Immunohistochemistry was used to analyze the rat brain distribution of thimet oligopeptidase and neurolysin. Both enzymes appear ubiquitously distributed within the entire rat brain. However, neuronal perikarya and processes stained for neurolysin, while intense nuclear labeling was only observed for thimet oligopeptidase. These data suggest that neurolysin and thimet oligopeptidase, endopeptidases sharing several functional and structural similarities, are present in distinctive intracellular compartments in neuronal cells.

Animals↗
PubMed1999

The association of metalloendopeptidase EC 3.4.24.15 at the extracellular surface of the AtT-20 cell plasma membrane.

Endopeptidase EC 3.4.24.15 (EP24.15) is a soluble, neuropeptide-degrading metalloenzyme, widely expressed in the brain, pituitary and gonads. For the physiological metabolism of neuropeptides, the enzyme should be located extracellularly, either associated with the plasma membrane or in the extracellular milieu. Western immunoblot analyses of crude cytosolic and post-nuclear membrane fractions prepared by differential centrifugation revealed a slightly smaller molecular mass ( approximately 2 kDa) for EP24.15 in the post-nuclear membrane fraction. This smaller EP24.15 species was also present in an enriched fraction of plasma membrane prepared by Percoll gradient centrifugation. To ascertain whether EP24.15 is associated with the extracellular surface of plasma membrane, two sets of experiments were carried out. First, Western immunoblot analysis of AtT-20 cells treated with the membrane-impermeable, thiol-cleavable cross-linker, 3, 3'-dithio-bis(sulpho-succinimidyl-propionate) (DTSSP), indicated an extracellular membrane association. After cross-linking and thiol-reduction, a distinct band corresponding to EP24.15 was significantly diminished under non-reducing conditions. Second, immunocytochemical studies performed at 4 degrees C on non-permeabilized AtT-20 cells (i.e., non-fixed to prevent antibody internalization), indicated that EP24.15 was expressed on the surface of the AtT-20 cells. We furthermore determined that EP24.15 enzymatic activity is present on the extracellular surface of the cell discernable from the secreted enzyme. These results suggest that the EP24.15 is associated with the extracellular surface of the AtT-20 cell plasma membrane and is enzymatically active. Taken together, the results are consistent with a putative role in the degradation of neuropeptides acting at the external cell surface.

Animals↗
PubMed1999

Hematopoietic stem-cell transplantation for the treatment of severe combined immunodeficiency.

BACKGROUND: Since 1968 it has been known that bone marrow transplantation can ameliorate severe combined immunodeficiency, but data on the long-term efficacy of this treatment are limited. We prospectively studied immunologic function in 89 consecutive infants with severe combined immunodeficiency who received hematopoietic stem-cell transplants at Duke University Medical Center between May 1982 and September 1998. METHODS: Serum immunoglobulin levels and lymphocyte phenotypes and function were assessed and genetic analyses performed according to standard methods. Bone marrow was depleted of T cells by agglutination with soybean lectin and by sheep-erythrocyte rosetting before transplantation. RESULTS: Seventy-seven of the infants received T-cell-depleted, HLA-haploidentical parental marrow, and 12 received HLA-identical marrow from a related donor; 3 of the recipients of haploidentical marrow also received placental-blood transplants from unrelated donors. Except for two patients who received placental blood, none of the recipients received chemotherapy before transplantation or prophylaxis against graft-versus-host disease. Of the 89 infants, 72 (81 percent) were still alive 3 months to 16.5 years after transplantation, including all of the 12 who received HLA-identical marrow, 60 of the 77 (78 percent) who were given haploidentical marrow, and 2 of the 3 (67 percent) who received both haploidentical marrow and placental blood. T-cell function became normal within two weeks after transplantation in the patients who received unfractionated HLA-identical marrow but usually not until three to four months after transplantation in those who received T-cell-depleted marrow. At the time of the most recent evaluation, all but 4 of the 72 survivors had normal T-cell function, and all the T cells in their blood were of donor origin. B-cell function remained abnormal in many of the recipients of haploidentical marrow. In 26 children (5 recipients of HLA-identical marrow and 21 recipients of haploidentical marrow) between 2 percent and 100 percent of B cells were of donor origin. Forty-five of the 72 children were receiving intravenous immune globulin. CONCLUSIONS: Transplantation of marrow from a related donor is a life-saving and life-sustaining treatment for patients with any type of severe combined immunodeficiency, even when there is no HLA-identical donor.

B-Lymphocytes↗
PubMed1999

Late pelvic recurrence of nonseminomatous testicular carcinoma after negative retroperitoneal lymph node dissection.

We report a case of pathologic Stage I teratoma recurring in the pelvis as embryonal carcinoma 12 years after radical orchiectomy and bilateral retroperitoneal lymph node dissection (RPLND). The patient received three cycles of chemotherapy (cisplatin, etoposide, bleomycin) followed by complete surgical excision of the pelvic mass. Successful treatment of these rare late recurrences usually requires chemotherapy and complete surgical excision. Pelvic relapse may potentially result from incomplete iliac node resection at the time of RPLND, altered lymphatic drainage from an incompletely resected spermatic cord, or a second primary extragonadal tumor focus. Our case emphasizes the importance of meticulous surgical technique during RPLND and the necessity for follow-up beyond 5 years in patients with testicular cancer.

Adult↗
PubMed1999

Targeted deletion of the Vgf gene indicates that the encoded secretory peptide precursor plays a novel role in the regulation of energy balance.

To determine the function of VGF, a secreted polypeptide that is synthesized by neurons, is abundant in the hypothalamus, and is regulated in the brain by electrical activity, injury, and the circadian clock, we generated knockout mice lacking Vgf. Homozygous mutants are small, hypermetabolic, hyperactive, and infertile, with markedly reduced leptin levels and fat stores and altered hypothalamic proopiomelanocortin (POMC), neuropeptide Y (NPY), and agouti-related peptide (AGRP) expression. Furthermore, VGF mRNA synthesis is induced in the hypothalamic arcuate nuclei of fasted normal mice. VGF therefore plays a critical role in the regulation of energy homeostasis, suggesting that the study of lean VGF mutant mice may provide insight into wasting disorders and, moreover, that pharmacological antagonism of VGF action(s) might constitute the basis for treatment of obesity.

Aggression↗
PubMed1999

Marie Unna congenital hypotrichosis: clinical description, histopathology, scanning electron microscopy of a previously unreported large pedigree.

Marie Unna congenital hypotrichosis (MUCH) is a rare autosomal dominant condition in which abnormalities are confined to hair shaft structure and hair density. We report a six-generation pedigree consisting of 59 members of whom 16 are affected; nine identified affected individuals are living. Affected individuals are born with adequate, normal to coarse hair. During early infancy the scalp hair becomes more coarse and wiry and stands out from the head. All affected individuals have sparse to absent eyebrows, eyelashes and body hair including secondary sexual hair. In some individuals, scalp hair is progressively lost beginning at puberty or beyond, until only a sparse fringe in the tonsorial distribution remains. The hair shafts are uniformly increased in diameter, measuring up to 0.12 mm. Individual hair shafts are deeply pigmented, variable in diameter, twisted, and bent at odd angles; some have a longitudinal groove visible on scanning electron microscopy. Cross-sectional shapes are variable and irregular, exhibiting oval, angular to reniform shapes. Multiple anagen hairs are extractable on gentle hair pull. Other ectodermal structures are unaffected except for exceptionally widely spaced upper incisor teeth seen in 50% of affected individuals. Histologically, there are dramatically reduced numbers of follicles per unit area, averaging nine total hairs per 4 mm cross-section as compared with a normal of 40. A mild to moderate inflammatory infiltrate is present, but little fibrosis and no scarring. The mechanism of progressive hair loss is unknown.

Adolescent↗
PubMed1999

Secretion of metalloendopeptidase 24.15 (EC 3.4.24.15).

The metalloendopeptidase EP24.15 (EC3.4.24.15) is a neuropeptide-metabolizing enzyme present in neural and endocrine tissues, presumably functioning extracellularly. Because the majority of the EP24.15 activity is identified in the soluble fraction of cellular homogenates, suggesting that the enzyme is primarily an intracellular protein, we addressed the issue of how EP24.15 arrives in the extracellular environment. We utilized a model system of neuroendocrine secretion, the AtT20 cell. According to both enzymatic activity and immunologic assays, EP24.15 was synthesized in and released from AtT20 cells. Under basal conditions and after stimulation by corticotropin-releasing hormone or the calcium ionophore A23187, EP24.15 activity accumulated in the culture medium. This secretion was not attributable to cell damage, as judged by the absence of release of cytosolic enzyme markers and the ability to exclude trypan blue dye. Pulse-chase analysis and subcellular fractionation of AtT20 cell extracts suggested that the mechanism of EP24.15 secretion is not solely via classical secretory pathways. Additionally, drugs which disrupt the classical secretory pathway, such as Brefeldin A and nocodazole, blocked A23187-stimulated EP24.15 release yet had no effect on basal EP24.15 release, suggesting differences in the basal and stimulated pathways of secretion for EP24.15. In summary, EP24.15 appears to be secreted from AtT20 pituitary cells into the extracellular milieu, where the enzyme can participate in the physiologic metabolism of neuropeptides.

Animals↗
PubMed1999

Fasting regulates hypothalamic neuropeptide Y, agouti-related peptide, and proopiomelanocortin in diabetic mice independent of changes in leptin or insulin.

Fasting increases hypothalamic neuropeptide Y (NPY) and agouti-related peptide (AGRP) messenger RNA (mRNA) and reduces hypothalamic POMC mRNA, and is also characterized by a reduction in plasma leptin, insulin, and glucose, each of which has been implicated in the regulation of hypothalamic gene expression. To further evaluate the roles of leptin, insulin, and glucose in mediating effects of fasting, we examined hypothalamic gene expression in nondiabetic and streptozotocin (STZ)-induced diabetic mice both under ad lib fed and 48-h fasted conditions. In both diabetic and nondiabetic mice, fasting stimulated hypothalamic NPY and AGRP mRNA and inhibited hypothalamic POMC mRNA and adipose leptin mRNA. However, in diabetic mice fasting had no effect on plasma leptin and insulin while decreasing plasma glucose, whereas in nondiabetic mice fasting decreased plasma leptin, insulin, and glucose. Furthermore, in nondiabetic fasted mice, NPY and AGRP mRNA were higher, and POMC mRNA and plasma glucose were lower, than in diabetic ad lib fed mice, even though insulin and leptin were similar in these two groups. These data are consistent with the hypothesis that although leptin and insulin regulate hypothalamic gene expression, glucose or other factors may have independent effects on hypothalamic and adipose gene expression under conditions of low insulin and leptin.

Adipose Tissue↗
PubMed1999

Mechanisms for the regulation of gonadotropin-releasing hormone gene expression in the developing mouse.

The release of GnRH peptide from neuroterminals in the median eminence increases during postnatal development. We were interested in determining the biosynthetic component contributing to the regulation of GnRH decapeptide levels, and ascertaining the molecular mechanism for these changes. Male and female C57bl/6 mice, from embryonic day (E)16 through postnatal day (P)60, were killed, and the preoptic area-anterior hypothalamus was dissected out. Cytoplasmic and nuclear RNA were extracted separately. Levels of GnRH messenger RNA (mRNA) and primary transcript were quantitated in individual preoptic area-anterior hypothalamus cytoplasmic and nuclear fractions, respectively, by ribonuclease protection assays. Serum LH levels were assayed by RIA. GnRH mRNA levels in the cytoplasm increased gradually and significantly during postnatal development in both males and females, reaching a peak at P55 in females and P40 in males. GnRH primary transcript levels in the nucleus, an index of GnRH gene transcription, changed in a completely different manner developmentally, and they differed between male and female mice. GnRH primary transcript levels in males were quite low until P5, when they underwent an increase of approximately 4-fold, between P5 and P7. They continued to increase through P15, at which time they reached adult levels. In females, GnRH primary transcript levels were high at E16, decreased to a nadir at P5, and then underwent an increase of approximately 5-fold to P7, which were comparable with adult levels. The large and sexually dimorphic changes in GnRH primary transcript between E16 and P7, in the absence of similar changes in GnRH mRNA, suggest that differential mechanisms, such as gene transcription and mRNA stability, play a role in determining levels of GnRH mRNA at different stages of development.

Aging↗
PubMed1999

Immediate and postoperative complications of transurethral prostatectomy in the 1990s.

PURPOSE: We compare the morbidity, mortality, hospitalization and urethral catheter time of contemporary transurethral prostatectomy to historical series, and evaluate recent trends in hospitalization and urethral catheter time during the last 8 years. MATERIALS AND METHODS: A retrospective chart review of 520 consecutive patients who underwent transurethral prostatectomy between 1991 and 1998 at a single institution for symptomatic benign prostatic hyperplasia was performed. Inpatient and outpatient charts, clinic records, operative reports and discharge summaries were reviewed. For each patient 43 data points were collected. Telephone followup was performed when data were lacking. All retrieved data were compiled in a computer database. Perioperative and late postoperative morbidity and mortality, hospitalization and urethral catheter time were analyzed. RESULTS: A total of 520 patients were identified with an average age of 67 years (range 44 to 89). Significant co-morbidity (2 or more co-morbid disease processes) was identified preoperatively in 30.3% of the patients. The most common indications for transurethral prostatectomy were lower urinary tract symptoms (80.9%) and urinary retention (15.2%). Average preoperative International Prostate Symptom Score was 23.8. Average weight of resected tissue was 18.8 gm. There was no perioperative patient mortality. Blood transfusion rate was 0.4%. The rate of intraoperative and immediate postoperative complications was 2.5% and 10.8%, respectively. Average hospital stay was 2.4 days, and 1.1 from 1997 through 1998. The rate of late postoperative complication was 8.5% and the average postoperative symptom score was 6.4 with an average followup of 42 months (range 6 to 84). CONCLUSIONS: Contemporary perioperative and postoperative complications of transurethral prostatectomy are significantly lower than rates in historical series. The average hospital stay and urethral catheter time have steadily decreased during the last 8 years.

Adult↗
PubMed1999

Clinical dose ranging studies with finasteride, a type 2 5alpha-reductase inhibitor, in men with male pattern hair loss.

BACKGROUND: Androgenetic alopecia is a common condition of adult men. Finasteride, a type 2 5alpha-reductase inhibitor, decreases the formation of dihydrotestosterone from testosterone. OBJECTIVE: Two separate clinical studies were conducted to establish the optimal dose of finasteride in men with this condition. METHODS: Men from 18 to 36 years of age with moderate vertex male pattern hair loss received finasteride 5, 1, 0.2, or 0.01 mg/day or placebo based on random assignment. Efficacy was determined by scalp hair counts, patient self-assessment, investigator assessment, and assessment of clinical photographs. Safety was assessed by clinical and laboratory measurements and by analysis of adverse experiences. RESULTS: Efficacy was demonstrated for all end points for finasteride at doses of 0.2 mg/day or higher, with 1 and 5 mg demonstrating similar efficacy that was superior to lower doses. Efficacy of the 0.01 mg dose was similar to placebo. No significant safety issues were identified in the trials. CONCLUSION: Finasteride 1 mg/day is the optimal dose for the treatment of men with male pattern hair loss and was subsequently identified for further clinical development.

5-alpha Reductase Inhibitors↗
PubMed1998

Role of JAK3 in CD40-mediated signaling.

CD40 is a member of the tumor necrosis factor receptor family and plays an important role in B-cell survival, growth, differentiation, and isotype switching. Recently, CD40 has been shown to associate with JAK3, a member of the family of Janus Kinases, which are nonreceptor protein kinases involved in intracellular signaling mediated by cytokines and growth factors. To investigate the role of JAK3 in CD40-mediated signaling, we studied the effect of CD40 stimulation on B-cell proliferation, IgE isotype switching, and upregulation of surface expression of CD23, ICAM-1, CD80, and LT-alpha in JAK3-deficient patients. Our studies show that stimulation of B cells with monoclonal antibody to CD40 in the presence of interleukin-4 (IL-4) or IL-13 resulted in similar responses in JAK3-deficient patients and normal controls. This suggests that JAK3 is not essential for CD40-mediated B-cell proliferation, isotype switching, and upregulation of CD23, ICAM-1, CD80, and LT-alpha surface expression.

Antigens, Surface↗
PubMed1998

Neuropeptide specificity and inhibition of recombinant isoforms of the endopeptidase 3.4.24.16 family: comparison with the related recombinant endopeptidase 3.4.24.15.

Endopeptidase EC 3.4.24.16 (EP24.16c, neurolysin) and thimet oligopeptidase EC 3.4.24.15 are close related members of a large family of metalloproteases. Besides their cytosolic and membrane bound form, endopeptidase EC 3.4.24.16 appears to be present in the inner membrane of the mitochondria (EP24.16m). We have overexpressed two porcine EP24.16 isoforms in E. coli and purified the recombinant proteins to homogeneity. We show here that these peptidases hydrolyse a series of neuropeptides with similar rates and at sites reminiscent of those elicited by classically purified human brain EP24.16c. All neuropeptides, except neurotensin, were similarly cleaved by recombinant endopeptidase 3.4.24.15 (EP24.15, thimet oligopeptidase), another zinc-containing metalloenzyme structurally related to EP24.16. These two EP24.16 isoforms were drastically inhibited by Pro-Ile and dithiothreitol and remained unaffected by a specific carboalkyl inhibitor (CFP-AAY-pAb) directed toward the related EP24.15. The present purification procedure of EP24.16 should allow to establish, by mutagenesis analysis, the mechanistic properties of the enzyme.

Amino Acid Sequence↗