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J Schwartz

Publications and source records attributed to J Schwartz.

At least 181 records · Page 10Linked to original sources
PubMed1997

Developmental changes in ovine corticotrophs in vitro.

We recently reported that fetal sheep corticotrophs (ACTH-producing cells) at 108 +/- 5 d (days) of gestation are relatively more responsive to CRH than to AVP, whereas those at 139 +/- 0 d (term = 145 d) and in the adult are more responsive to AVP. To further characterize these developmental changes, we used immunocytochemical, RIA, and cell immunoblotting techniques to examine populations of corticotrophs and individual cells. Immunocytochemical studies revealed that corticotroph frequency decreased from 22 +/- 1% of all pituitary cells at 100 d of gestation to 14 +/- 1% at 135 d and 9 +/- 0% in the adult. RIA measurements of ACTH secretion by cell populations showed that the response of corticotrophs to CRH diminished, whereas that to AVP increased during gestation and into adulthood. Cell blot analysis of individual corticotrophs identified two types of secretory responses (increases in the number of secreting cells and average amount of ACTH released per cell) to CRH or AVP that changed during fetal development. At 100 d of gestation, CRH increased the proportion of secreting cells from 65 +/- 3% (no test agent) to approximately 90%; AVP exerted a negligible effect on the relative abundance of secreting cells. At 120 d of gestation, both secretagogues, alone or in combination, increased the proportion of secreting corticotrophs from 49 +/- 6% to about 85%. At 135 d of gestation and in the adult, AVP, alone or in combination with CRH, increased secreting corticotrophs from about 53 +/- 6% to about 80%. CRH alone exerted a nominal effect on the proportion of secreting cells. Additional analyses showed that, at 100 or 120 d of gestation, the average amount of ACTH secreted by individual corticotrophs did not change in response to CRH or AVP. However, near term and into adulthood, the average quantity of ACTH released from individual cells increased in response to these agents. Our findings suggest that maturational changes in fetal corticotrophs dictate whether their secretory response to CRH or AVP results from an increase in the proportion of cells secreting ACTH and (or) an increase in the average amount of hormone secreted by individual cells.

Adrenocorticotropic Hormone↗
PubMed1997

Growth hormone-induced tyrosyl phosphorylation and deoxyribonucleic acid binding activity of Stat5A and Stat5B.

GH is known to activate JAK2 tyrosine kinase and members of the Stat family of transcription factors, including Stats 1, 3, and 5. The recent observation that at least two Stat5 proteins (Stat5A and Stat5B) exist in mouse and human, raises the question of whether GH activates both Stat5A and Stat5B and, if so, whether the requirements for activation are the same. An initial report investigating this issue demonstrated GH-dependent activation of Stat5A but not Stat5B. In this paper, we demonstrate (in COS cells expressing rat GH receptor (rGHR) and either Stat5A or Stat5B, 3T3-F442A fibroblasts, and CHO cells expressing rGHR) that GH induces tyrosyl phosphorylation of both Stat5A and Stat5B. Similar time courses of phosphorylation were observed for the two proteins. Interestingly, the pattern of observed bands differs for the two forms of Stat5. Two closely migrating Stat5A bands can be detected in cells treated with or without GH. Both of these bands become tyrosyl phosphorylated in response to GH. Three species of Stat5B are observed in untreated cells. An additional, more slowly migrating Stat5B band, appears upon treatment with GH. The three more slower migrating Stat5B bands observed in response to GH contain phosphorylated tyrosyl residues. We further demonstrate that GH induces binding of Stat5A and Stat5B, as well as Stat1, to the GAS-like element in the beta-casein promoter. We and others have demonstrated previously that specific regions of GHR are required for GH-dependent activation of what is here identified as Stat5B. To gain insight into the mechanism by which GH promotes tyrosyl phosphorylation of Stat5A, GH-dependent tyrosyl phosphorylation of Stat5A was examined in CHO cells expressing truncated and mutated rGHR. The results indicate that Stat5A and Stat5B require the same regions of rGHR for maximal activation by GH: the C-terminal half of the cytoplasmic domain; tyrosines 333 and/or 338 in the N-terminal half of the cytoplasmic domain; and the regions required for JAK2 activation. To dissect further the mechanism by which GH activates Stat5A and B, the requirement for JAK2 in GH-dependent Stat5 tyrosyl phosphorylation was assessed using JAK2-deficient cells expressing GHR (gamma2A-GHR) and the wild-type parental cell line expressing GHR (2C4-GHR). GH-induced tyrosyl phosphorylation of Stat5B in 2C4-GHR cells but not in the JAK2 deficient, gamma2A-GHR cells, indicating that JAK2 is required for GH-dependent tyrosyl phosphorylation of Stat5B. Western blotting revealed that Stat5A is not expressed in this cell type. Taken together, these findings suggest that: 1) GH activates both Stat5A and Stat5B in several cell types; 2) the pattern of bands observed differs for Stat5A and Stat5B; 3) GH-dependent tyrosyl phosphorylation of Stat5A requires specific regions of GHR, and these requirements are the same as for Stat5B; and 4) JAK2 kinase is required for GH-dependent tyrosyl phosphorylation of Stat5B and, most likely, Stat5A.

Animals↗
PubMed1997

Effects of vasopressin and elimination of corticotropin-releasing hormone-target cells on pro-opiomelanocortin mRNA levels and adrenocorticotropin secretion in ovine anterior pituitary cells.

Although arginine-vasopressin (AVP) is reported to produce greater ACTH biosynthetic and secretary responses than does corticotropin-releasing hormone (CRH) in sheep anterior pituitary cells, neither factor appears to increase pro-opiomelanocortin (POMC) mRNA levels, as does CRH in the cells of some other species. Since only a fraction of cells that express POMC mRNA may be able to respond to AVP, the aim of this study was to further delineate the regulation of POMC mRNA in ovine anterior pituitary corticotrophs, as a whole and in functional subpopulations of corticotrophs. We measured the effects of AVP, CRH or activation of protein kinase C by phorbol myristate acetate (PMA) in cultured cells. We compared responses in intact populations with those of cultures from which CRH-target cells were pharmacologically eliminated. Dissociated adult ovine anterior pituitary cells were cultured overnight, treated with either vehicle (intact) or a CRH-toxin conjugate that specifically eliminates CRH-target cells (CRH-target-depleted), washed, returned to culture and subsequently challenged with vehicle, AVP (100 nM), CRH (10 nM) or PMA (1 microM) for 5 h. The media were assayed for ACTH by RIA and the cells for POMC mRNA by Northern blot analysis. In intact populations, AVP and CRH increased ACTH secretion from 6.5 +/- 1.2 to 216 +/- 22 and 81 +/- 14 ng/well respectively, but only AVP caused an increase in steady-state POMC mRNA levels (+48 +/- 10%). Direct activation of protein kinase C with PMA mimicked the effect of AVP on ACTH secretion (318 +/- 16 ng/well), but did not alter POMC mRNA levels. In CRH-target-depleted populations, control ACTH secretion (11 +/- 3 ng/well) and POMC mRNA (+69 +/- 7%) were elevated, compared with intact populations. AVP (55 +/- 8 ng/well) and PMA (120 +/- 17 ng/ well), but not CRH, increased ACTH secretion; POMC mRNA was not significantly elevated by any of the treatments. Taken together, these data provide further support for the notion of dissociation between secretion of ACTH and expression of POMC mRNA, and demonstrate that AVP increases steady-state POMC mRNA levels in ovine anterior pituitary cells. The data are also consistent with the concept that complex interactions, possibly including those between cells, influence ACTH secretion and steady-state POMC mRNA levels.

Adrenocorticotropic Hormone↗
PubMed1997

Clozapine and haloperidol modulate N-methyl-D-aspartate- and non-N-methyl-D-aspartate receptor-mediated neurotransmission in rat prefrontal cortical neurons in vitro.

The effects of the antipsychotic drugs haloperidol and clozapine on N-methyl-D-aspartate (NMDA) and non-NMDA receptor-mediated neurotransmission were examined and compared in pyramidal cells of the medial prefrontal cortex in rat brain slices by using the techniques of intracellular recording and single-electrode voltage-clamp. The bath administration of either haloperidol or clozapine produced a marked facilitation (300-400%) of NMDA-evoked responses in a concentration-dependent manner. The EC50 values of haloperidol and clozapine were 38 and 14 nM, respectively. At concentrations of > or =100 nM, clozapine, but not haloperidol, produced bursts of excitatory postsynaptic potentials (EPSPs), which were blocked by glutamate receptor antagonists, suggesting that these EPSPs were the result of increasing release of excitatory amino acids. Haloperidol, but not clozapine, produced a concentration-dependent inhibition of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced current with an EC50 value of 37 nM. Haloperidol significantly decreased the amplitude of EPSPs evoked by the electrical stimulation of the forceps minor, whereas clozapine increased the amplitude of these EPSPs. The study of current-voltage relationship indicates that clozapine preferentially potentiates NMDA receptor-mediated transmission, whereas haloperidol depresses the non-NMDA receptor-mediated response, which probably obscures its potentiating effect on NMDA receptor-mediated EPSPs.

Action Potentials↗
PubMed1996

Antipicornavirus activity of SCH 47802 and analogs: in vitro and in vivo studies.

SCH 47802 and its derivatives are potent inhibitors of enteroviruses in vitro. The IC50 for SCH 47802 ranges from 0.03 to 10 micrograms/ml when tested against a spectrum of enteroviruses in plaque reduction assays. The compounds have in vitro therapeutic indices of at least 81 based on viral cytopathic effect (CPE) assays. The in vitro activity of SCH 47802 translates into in vivo activity in the murine model of poliovirus encephalitis. In an oral dosing regimen, SCH 47802 protects mice from mortality at 60 mg/kg per day. Consistent with the in vivo efficacy, pharmacokinetic analyses after oral dosing with SCH 47802 demonstrate serum levels of the compound above the in vitro IC50 for poliovirus for at least 4 h. SCH 47802 and its active analogs stabilize poliovirus to thermal inactivation indicating that the compounds bind to the virus capsid. Mechanistic studies with poliovirus indicate that SCH 47802 acts early in viral infection. This series of molecules represents potential candidates for the treatment of human enterovirus infections.

Animals↗
PubMed1996

Air pollution and hospital admissions for respiratory disease.

Several recent studies have reported associations between short-term changes in air pollution and respiratory hospital admissions. Most of those studies analyzed locations where there was a high correlation between airborne particles and sulfur dioxide (SO2), and between all air pollutants and temperature. Here, I seek to replicate the previous findings in a location where SO2 concentrations were trivial, and the correlation between both airborne particles and ozone with temperature was considerably lower than in previous studies. I constructed daily counts of admissions to all hospitals in Spokane, WA, for respiratory disease (International Classification of Diseases, 9th revision, codes 460-519) for persons age 65 years and older. I computed average daily concentrations of airborne particles whose diameter is 10 microns or less (PM10) and ozone (O3) from all monitors in each city, and I obtained daily average temperature and humidity from the U.S. weather service. SO2 concentrations in Spokane were so low that monitoring was discontinued. I regressed daily respiratory admission counts on temperature, humidity, day of the week indicators, and air pollution. I used a Poisson regression analysis and removed long wavelength patterns using a nonparametric smooth function of day of study. I dealt with a possible U-shaped dependence of admissions on temperature and/or humidity by using nonparametric smooth functions of weather variables as well. I then examined sensitivity analyses to control for weather. Both PM10 and ozone were associated with increased risk of respiratory hospital admissions [relative risk (RR) = 1.085; 95% confidence interval (CI) = 1.036-1.136 for a 50-microgram per m3 increase in PM10, and RR = 1.244; 95% CI = 1.002-1.544 for a 50-microgram per m3 increase in peak-hour ozone]. The PM10 association was insensitive to alternative methods of control for weather, including exclusion of extreme temperature days and control for temperature on multiple days. The ozone results were more sensitive to the approach for weather control. The magnitude of the PM10 effect in this location, where SO2 was essentially not present, and where the correlation between PM10 and temperature was close to zero, was similar to that reported in other locations in the eastern United States and Europe, where confounding by weather and SO2 is a more substantial concern.

Aged↗
PubMed1996

Air pollution and daily mortality in Amsterdam.

Few data are available on the association between the present low levels of air pollution in Western Europe and mortality. Daily mortality counts and the concentrations of black smoke, inhalable particles (PM10), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) were available for Amsterdam from 1986 to 1992. We used Poisson regression analysis to control for seasonal and other long-term temporal patterns. Black smoke and PM10 were positively associated with increased risk of mortality. The relative risk for a 100-micrograms per m3 increase in black smoke on the same day was 1.19 [95% confidence interval (CI) = 1.02-1.38], and that for a 100-micrograms per m3 increase in PM10 was 1.06 (95% CI = 0.99-1.14). The relative risk for individuals over 64 years of age was higher. We found no consistent association between the levels of SO2 or CO and daily mortality, but ozone lagged 2 days was positively associated with daily mortality. The effect of particulates on acute mortality was independent of these pollutants. The results of the present study are consistent with the relation reported between particulate air pollution and daily mortality in other communities in Europe and the United States.

Air Pollution↗
PubMed1996

Psychiatric morbidity on entry to an HIV primary care clinic.

OBJECTIVE: To ascertain the prevalence and predictors of psychiatric distress in an inner-city HIV primary care clinic. DESIGN: Cross-sectional study. SETTING: Inner-city adult HIV clinic. PARTICIPANTS: A series of 222 HIV-infected patients newly presenting to the medical clinic for evaluation over a 1-year period. OUTCOME MEASURES: A screening method, based on the General Health Questionnaire (GHQ) and the Beck Depression Inventory (BDI), whose sensitivity, specificity and positive predictive value for psychiatric diagnosis were previously established in this clinic. RESULTS: Fifty-two per cent of participants scored above the screening threshold (i.e., scored > 14 on the BDI or > 6 on the GHQ). A comorbid substance use condition was the most powerful and consistent predictor of psychiatric distress (P < 0.05). Limited education and current unemployment contributed to higher scores on the BDI or the GHQ (P < 0.05). However, HIV illness variables and psychiatric personal or family histories were not significant predictors of psychiatric distress (P > 0.05 in all cases). CONCLUSIONS: Rates of psychiatric distress in inner-city adult HIV clinics are much higher than in the general population or than in other outpatient medical clinics. They are also not associated with what most clinicians perceive as traditional risk groups such as psychiatric histories and social disadvantage. These findings support the position that easy access to psychiatric care is essential to HIV clinics.

Adult↗
PubMed1996

Cutaneous T-cell lymphoma, tropical spastic paraparesis, cerebral vasculitis, and protein S deficiency in a patient with HTLV-I.

The clinical spectrum of retroviruses is expanding rapidly. Human T-cell lymphotropic virus type I (HTLV-I) was the first retrovirus to be described, and its role had been established in adult T-cell leukemia/lymphoma and tropical spastic paraparesis. We report the case of a 35-year-old woman with HTLV-I and the unusual combination of cutaneous T-cell lymphoma, tropical spastic paraparesis, cerebral vasculitis, and protein S deficiency. We discuss the relationship of all her diseases to HTLV-I.

Adult↗
PubMed1996

Silicone granuloma in acral skin in a patient with silicone-gel breast implants and systemic sclerosis.

A 68-year-old white woman was referred to us by her rheumatologist for possible participation in a clinical study of photopheresis for scleroderma. In February 1993, she noticed edema of her distal phalanges, Raynaud's phenomenon in both hands, flu-like symptoms, fatigue, intermittent diarrhea, abdominal pain, tearing in both eyes, dyspnea on exertion, dysphagia, and odynophagia. Bilateral silicone-gel breast implants had been placed 12 years before; 2 months before her present evaluation, they were removed and found to be ruptured. Physical examination revealed edema, limited to the fingers and hands bilaterally, and slight induration of the skin on the dorsum of both hands and distal forearms. The remainder of the physical examination was normal. According to our study protocol, a skin biopsy specimen from the dorsum of the right hand was taken, but all other laboratory investigations were refused. Histopathologic examination revealed multiple clear spaces of varying sizes in the dermis and multinucleated macrophages containing small refractile particles, characteristic of silicone granuloma (Figs. 1 and 2); however, the specimen showed no evidence of scleroderma. X-ray energy dispersive analysis by scanning electron-microscopy confirmed the presence of elemental silicon in the small refractile particles. The patient did not receive any treatment after her diagnosis and shortly thereafter, she was lost to follow-up.

Aged↗
PubMed1996

Cytolytic response to HIV in patients with HIV disease treated with extracorporeal photochemotherapy: preliminary study.

Extracorporeal photochemotherapy (photopheresis), an immunomodulatory therapy that targets circulating T helper lymphocytes, has been applied to the management of human immunodeficiency virus (HIV) disease. Any therapy that exerts its actions on CD4+ T cells has the potential of exacerbating HIV infection. Therefore, it was necessary to observe immune function during treatment. Because cytotoxic T lymphocytes (CTL) and natural-killer cells are thought to play an important role in the response against HIV infection, we examined the effect of photopheresis on HIV cytolytic activity. The study group consisted of seven patients with late-stage HIV disease who had not received any previous treatment for HIV infection. Patients were treated exclusively with photopheresis on two consecutive days each month for 14-32 months (average, 25 months). Peripheral lymphocytes, collected at various points during treatment, were used as effectors in a 51Cr release assay. Epstein-Barr virus (EBV)-transformed autologous B cell lines transfected with recombinant vaccinia vectors that expressed the HIV env (gp120, gp41) and gag (p24) proteins were used as target cells. All seven patients demonstrated relatively constant levels of cytolysis (>10% above controls) during treatment in the context of stable CD4+ T cell counts and a stable clinical status. These results suggest that extracorporeal photochemotherapy did not impair the cytolytic response to HIV infection and may have enhanced it in some patients.

Adult↗
PubMed1996

Expression and characterization of glutathione peroxidase activity in the human blood fluke Schistosoma mansoni.

Antioxidants may play an important role in immune evasion by schistosome parasites. Previous studies have focused on the roles of superoxide dismutase and glutathione S-transferase. In the present study, glutathione peroxidase (GPX) activity was measured in different fractions of worm extracts from several developmental stages of Schistosoma mansoni. The enzyme activity was shown to be developmentally regulated, with higher specific activities being found in the tegument-enriched Nonidet P-40 extract of adult worms (the stage least susceptible to immune killing) than in the larval stages (which are most susceptible to immune elimination). In all extracts tested, the activity against cumene hydroperoxide, even when glutathione S-transferase activity was removed, was higher than that for hydrogen peroxide. The expression of GPX cDNA in pGEX-2T by bacteria produced a 50-kDa fusion protein and a 32-kDa truncated protein. The latter was due to termination at the internal UGA codon that codes for selenocysteine. GPX activity was detected in the recombinantly produced GPX but not with Sj26-glutathione S-transferase from the vector. Mutating the TGA codon to TGT produced a full-length product, GPXm (19 kDa), that was used to produce 19 monoclonal antibodies. Anti-GPXm monoclonal antibodies recognized a 19-kDa molecule in adult-worm extract which, upon removal by immunoprecipitation, resulted in the loss of over 90% of the GPX activity, suggesting that a single form of GPX exists in the schistosome.

Animals↗
PubMed1996

Short term effects of air pollution on health: a European approach using epidemiologic time series data: the APHEA protocol.

BACKGROUND AND OBJECTIVES: Results from several studies over the past five years have shown that the current levels of pollutants in Europe and North America have adverse short term effects on health. The APHEA project aims to quantifying these in Europe, using standardised methodology. The project protocol and analytical methodology are presented here. DESIGN: Daily time series data were gathered for several air pollutants (sulphur dioxide; particulate matter, measured as total particles or as the particle fraction with an aerodynamic diameter smaller than a certain cut off, or as black smoke; nitrogen dioxide; and ozone) and health outcomes (the total and cause specific number of deaths and emergency hospital admissions). The data included fulfilled the quality criteria set by the APHEA protocol. SETTING: Fifteen European cities from 10 different countries with a total population over 25 million. METHODOLOGY: The APHEA collaborative group decided on a specific methodological procedure to control for confounding effects and evaluate the hypothesis. At the same time there was sufficient flexibility to allow local characteristics to be taken into account. The procedure included modelling of all potential confounding factors (that is, seasonal and long term patterns, meteorological factors, day of the week, holidays, and other unusual events), choosing the "best" air pollution models, and applying diagnostic tools to check the adequacy of the models. The final analysis used autoregressive Poisson models allowing for overdispersion. Effects were reported as relative risks contrasting defined increases in the corresponding pollutant levels. Each participating group applied the analyses to their own data. CONCLUSIONS: This methodology enabled results from many different European settings to be considered collectively. It represented the best available compromise between feasibility, comparability, and local adaptibility when using aggregated time series data not originally collected for the purpose of epidemiological studies.

Air Pollutants↗
PubMed1996

Methodological issues in studies of air pollution and daily counts of deaths or hospital admissions.

STUDY OBJECTIVE: To review the issues and methodologies in epidemiologic time series studies of daily counts of mortality and hospital admissions and illustrate some of the methodologies. DESIGN: This is a review paper with an example drawn from hospital admissions of the elderly in Cleveland, Ohio, USA. MAIN RESULTS: The central issue is control for seasonality. Both over and under control are possible, and the use of diagnostics, including plots, is necessary. Weather dependence is probably non-linear, and adequate methods are necessary to adjust for this. In Cleveland, the use of categorical variables for weather and sinusoidal terms for filtering season are illustrated. After control for season, weather, and day of the week effects, hospital admission of persons aged 65 and older in Cleveland for respiratory illness was associated with ozone (RR = 1.09, 95% CI 1.02, 1.16) and particulates (PM10 (RR = 1.12, 95% CI 1.01, 1.24), and marginally associated with sulphur dioxide (SO2) (RR = 1.03, 95% CI = 0.99, 1.06). All of the relative risks are for a 100 micrograms/m3 increase in the pollutant. CONCLUSIONS: Several adequate methods exist to control for weather and seasonality while examining the associations between air pollution and daily counts of mortality and morbidity. In each case, care and judgement are required.

Aged↗