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Biomedical subjects

S E Walker

Publications and source records attributed to S E Walker.

At least 109 records · Page 6Linked to original sources
PubMed1991

Pulmonary perivascular and interstitial inflammation in MRL/MpJ-lpr/lpr mice. III. Modulation by cyclophosphamide and sex hormones in 4- and 6-month-old animals.

Estradiol (E) abolished clearing of pulmonary inflammation in 2-month-old male MRL/MpJ-lpr/lpr (MRL/l) mice treated with cyclophosphamide (CY). To determine if this effect persisted in animals with advanced disease, we studied male and female MRL/l mice, aged 4 and 6 months (4M, 6M, 4F, and 6F, respectively). Mice were treated, beginning at 1 month of age, with saline, CY (12 mg/kg/day), CY + castration, CY + castration + testosterone (T) in females, and CY + castration + E in males. CY had no effect on pulmonary inflammation in 4M, possibly because of the development of relatively mild lesions. However, CY was highly effective in 6M. CY + castration + T significantly reduced overall inflammation in 6F and showed a trend in 4F. CY alone had a variable effect on bronchoalveolar lavage fluid (BALF) cells and BALF IgG in both males and females. However, concurrent treatment with T was required for histologic changes of pulmonary inflammation to fully respond to a high dose of CY in female mice. E-treated males had reduced responsiveness to CY.

Aging↗
PubMed1991

Inflammatory central nervous system disease in lupus-prone MRL/lpr mice: comparative histologic and immunohistochemical findings.

The brains of pathogen-free autoimmune MRL/lpr, NZBWF1 and NZB mice were examined for central nervous system (CNS) inflammation in premoribund 8-week-old animals and at ages when active systemic lupus erythematosus (SLE) was present. CNS inflammation was observed only in MRL/lpr mice. Immunohistochemical studies of brains from young MRL/lpr mice found that infiltrates were composed primarily of CD4+ cells. Older MRL/lpr mice (22 and 26 weeks of age) had CD4+ cells predominantly, but CD8+ and B220+ cells were also present. Perivascular leakage of IgG was a prominent and unexpected finding in the MRL/lpr model. Congenic MRL/+ mice with late-onset autoimmunity had no inflammatory cells in brain tissue, and there was no perivascular staining with IgG or albumin. Our findings suggest that MRL/lpr mice are a useful model for studies of lupus-associated CNS inflammatory disease, and perivascular leakage may be a primary mechanism for entry of IgG into the brain.

Animals↗
PubMed1991

Long-term anti-CD4 treatment of MRL/lpr mice ameliorates immunopathology and lymphoproliferation but fails to suppress rheumatoid factor production.

MRL/lpr mice were treated with anti-CD4 mAb to define the role of CD4+ T cells in the pathogenesis of autoimmune disease and the lymphoproliferation characteristic of the strain. Anti-CD4 treatment was not associated with adverse effects, and survival of treated mice was increased over that of rat IgG-treated controls. Renal function was preserved, and the histologic severity of glomerulonephritis was minimal in treated mice. Lymphoid tissues of mice receiving anti-CD4 were effectively depleted of CD4+ T cells, and lymphoproliferation was markedly reduced. Serum IgG, anti-Sm, and anti-dsDNA levels were reduced significantly, while serum IgM and IgM rheumatoid factor levels were unaffected by anti-CD4 treatment. These data show that in MRL/lpr mice lymphoproliferation, renal disease, anti-Sm and anti-dsDNA antibody production, and elevated IgG levels are all linked to CD4+ T cell function. In contrast, both total IgM and IgM rheumatoid factor production appear to be the result of B-cell activity that is not regulated by CD4+ T cells.

Animals↗
PubMed1991

Hormonal manipulation of the prenatal environment alters reproductive morphology and increases longevity in autoimmune NZB/W mice.

Steroid hormones, which affect development of reproductive traits, alter immune responses in rodents and appear to control severity of disease in F1 hybrid NZB/W mice, an animal model of systemic lupus erythematosus. We tested the hypothesis that exposure of NZB/W fetuses to altered hormonal environments would influence subsequent expression of autoimmune renal disease and affect longevity. NZB females, pregnant with NZB/W fetuses, were treated from Days 13-18 of gestation with testosterone or the antiandrogen, flutamide. Similar treatments were carried out in C57BL/6 dams mated to DBA/2 males to permit comparison with nonautoimmune hybrid mice. Serum concentrations of testosterone were greater in testosterone-implanted dams of both strains, but concentrations of estradiol were greater only in C57BL/6 dams treated with flutamide. Alpha fetoprotein (AFP), which binds estrogen and modulates immune responsiveness, was greater in serum from both groups of testosterone-treated dams, while flutamide treatment increased serum AFP only in NZB dams. We conclude that factors governing circulating estradiol and AFP differed in pregnant NZB and C57BL/6 females. Morphological analyses confirmed effects of hormonal manipulation on the developing fetuses. Testosterone implants resulted in female offspring with greater anogenital spaces, and treatment of dams with flutamide eliminated the expected difference between anogenital spaces in females and males. Effects of altered prenatal hormonal environments on immune-mediated disease in NZB/W offspring were examined in a longevity study. Early deaths were delayed in NZB/W females produced by flutamide-treated dams. An unexpected result was observed in NZB/W males. Male offspring from both testosterone- and flutamide-treated mothers lived longer than males from control dams. This paradox suggested that a characteristic shared by both groups of treated NZB dams had similar effects on the developing fetuses. It is proposed that elevated concentrations of AFP modulated the course of autoimmune disease and contributed to increased longevity in NZB/W offspring of treated dams.

Animals↗
PubMed1991

Effects of prolonged administration of the 19-nor-testosterone derivatives norethindrone and norgestrel to female NZB/W mice: comparison with medroxyprogesterone and ethinyl estradiol.

To evaluate effects of commonly used progestational estrogenic contraceptive steroids in a hormone-responsive model of lupus, we treated female NZB/W mice before clinical disease (6 wks of age) and after onset of lupus (24 wks of age) with doses of hormones titered to suppress reproduction. We report efficacy of norethindrone (NE) and norgestrel (NG), progestins derived from 19-nor-testosterone, in delaying expression of anti-DNA antibodies. Mice implanted with NG at 24 wks of age had prolonged lifespans. In contrast, the hydroxyprogesterone derivative, medroxyprogesterone acetate (MP), did not affect autoimmune disease. These observations suggest that prolonged administration of 19-nor-testosterone derivatives, in small doses adequate to suppress reproduction, may have ameliorative effects in systemic lupus erythematosus. Mice receiving ethinyl estradiol (EE) plus courses of tetracycline to suppress cystitis had active anti-DNA responses. In 60% of EE-treated mice, however, early deaths resulted from malignant lymphomas and complications of obstructive uropathy. Estrogen toxicity, rather than accelerated lupus, was the major cause of death in NZB/W mice treated with EE.

Animals↗
PubMed1991

Compatibility of dexamethasone sodium phosphate with hydromorphone hydrochloride or diphenhydramine hydrochloride.

The stability and compatibility of dexamethasone sodium phosphate and hydromorphone hydrochloride or diphenhydramine hydrochloride at various concentrations at room temperature was studied. Solutions containing equal volumes in the following ranges of concentrations were prepared: dexamethasone sodium phosphate 0-10 mg/mL, diphenhydramine hydrochloride 0-50 mg/mL, and hydromorphone hydrochloride 0-40 mg/mL. Samples of each combination were analyzed immediately after mixing and at 7 and 24 hours using a stability-indicating high-performance liquid chromatographic assay. The pH of each solution was measured, and each combination was visually inspected. Precipitation occurred in solutions containing dexamethasone and hydromorphone hydrochloride or diphenhydramine hydrochloride when equal volumes of the most concentrated solutions were mixed. Some of the combinations at lower concentrations were visually compatible, and more than 90% of the initial concentrations of both drugs (i.e., dexamethasone-hydromorphone and dexamethasone-diphenhydramine) remained in these compatible solutions. Dexamethasone is visually compatible with diphenhydramine or hydromorphone but only within specific concentration ranges. In visually compatible solutions, both drug combinations are stable for up to 24 hours at room temperature.

Chromatography, High Pressure Liquid↗
PubMed1991

Relationship of self-efficacy to pain behavior.

Our purpose was to examine the effects of self-efficacy on the pain behaviors exhibited by patients with rheumatoid arthritis (RA). Seventy-two patients with RA were assessed using a standardized videotaping procedure for rating specific pain behaviors such as limps, facial grimaces, and guarded movements. Patients also completed questionnaires measuring self-efficacy and depression. Hierarchical regression was used to assess the relationship between self-efficacy and pain behavior after the effects of demographic characteristics and disease activity were statistically controlled. Higher self-efficacy was found to be related to fewer pain behaviors. In contrast, depression was found to be unrelated to pain behavior. Our results indicate that the pain behaviors that patients with RA exhibit are related to their self-efficacy, not solely to their disease activity.

Arthritis, Rheumatoid↗
PubMed1991

Single-dose pefloxacin pharmacokinetics and metabolism in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).

Seven adult patients on continuous ambulatory peritoneal dialysis (CAPD) received one dose of pefloxacin, a novel quinolone antibiotic, orally and intravenously on two separate occasions to characterize the pharmacokinetics and metabolism of the drug. Concentrations of both pefloxacin and its active metabolite N-desmethyl-pefloxacin (norfloxacin) were measured in serum and dialysate by HPLC. Half-life, total body clearance and peritoneal clearance were determined. The overall elimination half-life was 19.9h. Relative to the IV dose the bioavailability following oral administration of pefloxacin was 76%. The mean serum and dialysate concentrations were similar up to 24 h after the oral or IV dose. After a 6-h dwell time the dialysate concentration of pefloxacin was 2.24 mg/L which is above the MIC90 for most bacteria responsible for peritonitis in CAPD patients. The peritoneal clearance of pefloxacin averaged 2.5 mL/min. Serum concentrations of the metabolite norfloxacin were less than 0.5 mg/L during the 24 h study period. We conclude that pefloxacin might be equally effective in the treatment of peritonitis of CAPD after oral or IV administration. Since the peritoneal clearance contributes insignificantly to the elimination of pefloxacin during CAPD, the proposed maintenance regimen of an oral or IV 400 mg dose/day seems to be a reasonable therapy for infections in CAPD patients.

Administration, Oral↗
PubMed1990

Anti-histone antibodies in the serum of autoimmune MRL and NZB/NZW1 F1 mice.

Anti-histone antibodies have been reported in a number of human autoimmune diseases, most notably idiopathic and drug-induced lupus erythematosus. In the current study, anti-histone antibody activity was detected using ELISA and electroblotting techniques in sera from autoimmune NZB/W, MRL-lpr, and MRL-(+)/+ mice. Anti-histone activity increased with age, maturing earlier in females, in both NZB/W and MRL-lpr mice. Testosterone treatment decreased anti-histone activity in NZB/W mice and estrogen treatment from 2 weeks of age increased anti-histone activity in MRL-lpr mice, suggesting that gonadal hormones modified the expression of autoantibodies recognizing these protein antigens. Estrogen also increased serum IgG levels in MRL-lpr mice. Sex hormones affected expression of antibodies recognizing soy milk proteins but not ovalbumin in a similar manner. Nitrocellulose Western blots of SDS gels probed with sera from both types of autoimmune mice most often demonstrated reactivity with histone1. Some mice, usually mature females, also recognized histone4, histone3, and histone2.

Aging↗
PubMed1990

Epidermal ornithine decarboxylase induction and mouse skin tumor promotion by quinones.

The generation of reactive oxygen species and the subsequent development of a pro-oxidant state, such as occurs during the redox cycling of quinones, has been suggested to play a role in the tumor promotion. Moreover, we have recently shown that the relative tumor promoting activity of a series of structurally related anthrones correlated with their ability to undergo base-catalyzed oxidation. We therefore analyzed dose-response relationships for skin tumor promoting activity and the ability to induce epidermal ornithine decarboxylase (ODC) with a series of structurally related quinones. Single topical applications of 1,4-naphthoquinone and its 5-hydroxy analog (juglone) produced dose-dependent increases in epidermal ODC activity in the dose range 880-3520 nmol/mouse. These two quinones also promoted papilloma formation in female SENCAR mice initiated with 25 nmol 7,12-dimethylbenz[a]anthracene at doses capable of inducing epidermal ODC. The tumor promoting response with juglone (1760 nmol) was dependent upon the frequency of application, with the highest tumor response obtained with a three times per week application regimen. In contrast, neither 1,8-dihydroxy-9,10-anthraquinone nor 1,4-benzoquinone, at doses up to 1760 nmol/mouse, had any effect on epidermal ODC, nor did they possess tumor promoting activity after 31 weeks of promotion. Interestingly, 3-methyl-1,4-naphthoquinone (meadione), a relatively good redox cycling quinone, at a dose of 3520 nmol had only very weak ODC inducing activity and after 31 weeks of promotion (1760 nmol) did not produce a significant papilloma response in SENCAR mice. Thus, there was a good correlation between the ability of structurally related quinones to induce epidermal ODC and their ability to behave as tumor promoters. In contrast, a relationship between quinone redox cycling and tumor promotion was not readily apparent. Finally, under optimal promoting conditions, juglone was very effective at supporting the conversion of papillomas to carcinomas (carcinoma/papilloma ratio of 0.35). In addition, histological examination of all tumors produced during promotion with juglone revealed the presence of both kerathoacanthomas and sebaceous squamous cell carcinomas. These latter tumors, not found in the anthrone group, may be indicative of a potentially unique site and/or mechanism of action for this class of compounds.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Psychological screening in rheumatoid arthritis.

Our objective was to examine the utility of the Symptom Checklist-90-R (SCL-90-R) as a psychological screening instrument for patients with rheumatoid arthritis (RA). Subjects were 81 male and 3 female patients with classic or definite RA who were categorized into 3 anatomic stage groups based on roentgenograms. Erythrocyte sedimentation rates, joint counts, and the SCL-90-R were obtained on all subjects. In addition, rheumatologists were surveyed, and items were analyzed to identify potential disease related items on the SCL-90-R. Both the survey and the item analyses supported the utility of the SCL-90-R as a psychological screening instrument in a population with RA.

Aged↗
PubMed1989

Bioavailability of iron in oral ferrous sulfate preparations in healthy volunteers.

The bioavailability of iron in five ferrous sulfate preparations was studied in 10 healthy male volunteers. The preparations were an oral solution, two types of film-coated tablets and two types of enteric-coated tablets. Blood samples were drawn hourly from 8 am to 6 pm on the day before each study day to assess baseline serum iron concentrations and on the study day. Spectrophotometry was used to measure the serum iron concentrations. The area under the curve (AUC), the maximum concentration and the time to achieve the maximum concentration were compared by analysis of variance. The enteric-coated preparations resulted in AUCs less than 30% of the AUC for the oral solution. The two film-coated products produced AUCs essentially equivalent to that of the oral solution. We conclude that the bioavailability of iron in the enteric-coated preparations was low, relative to that of the film-coated products and the oral solution, and that these products should not be considered interchangeable.

Administration, Oral↗
PubMed1989

Pain control and rational thinking. Implications for rheumatoid arthritis.

In this study, we examined the factor structure of the Coping Strategies Questionnaire and studied the relevance of the coping process to health status in rheumatoid arthritis patients. The 2 factors of the questionnaire that were analyzed were Coping Attempts and Pain Control and Rational Thinking. The Pain Control and Rational Thinking factor was related to pain and psychological status, even after demographic variables and disease severity were statistically controlled. In addition, increases in Pain Control and Rational Thinking scores were related to improvements in pain, psychological status, and health status. Implications for the psychological care of rheumatoid arthritis patients are discussed.

Adaptation, Psychological↗
PubMed1989

The RHJ/Le rhino mutant: description of a unique murine model of autoimmunity.

The BALB/c HuDI-hrrh rhino mutant, which is no longer available, was an unusual murine model with prominent hepatic inflammation and fibrosis. The current report describes the early appearance of hepatic portal tract inflammation and antinuclear antibodies in the RHJ/Le mouse, a related rhino mutant which is distributed from a commercial source. All homozygous RHJ/Le rhino (hrrh hrrh) mice examined serially from 2 to 18 months of age developed inflammation of hepatic portal tracts. In 81 per cent of mice, portal and central veins were infiltrated with mononuclear cells. Focal infiltrates were found in salivary, Harderian and lacrimal glands and in the pancreas. Isolated animals had myositis involving skeletal muscle and myocardium. Heterogeneous antinuclear antibodies were detected in sera from 100 per cent of rhino mice and antibodies to DNA were present in 28 per cent of mice aged 6 months. Homozygous HRS/J hairless (hr/hr) and BALB/c controls failed to show consistent abnormalities in exocrine glands or liver. We conclude that the RHJ/Le rhino mutant spontaneously develops antinuclear antibodies and mononuclear cell infiltration in liver and exocrine glands. These animals provide unique opportunities to examine inflammatory lesions localized to specific target organs in an animal model of autoimmunity.

Animals↗
PubMed1989

Trimethoprim-sulfamethoxazole pharmacokinetics during continuous ambulatory peritoneal dialysis (CAPD).

Ten adult patients on continuous ambulatory peritoneal dialysis (CAPD) received one dose of trimethoprim-320 mg (TMP) and sulfamethoxazole 1600 mg (SMX) orally (p.o.), intravenously (i.v.), and intraperitoneally (i.p.) on three separate occasions to characterize the pharmacokinetics of both drugs. Concentrations of both TMP and SMX were measured in serum and dialysate by HPLC to 48 h. Half-life, total body clearance (TBC), and peritoneal clearance (PCl) were determined. The mean half-life of TMP was 28 h, while for SMX it was 12.5 h. Relative to the i.v. dose, the bioavailability following oral administration for TMP was 98% and 87% for SMX. Intraperitoneal bioavailability was 73% for TMP and 65% for SMX after a 4-h dwell. After 24 h, regardless of the route of administration, less than 3% of TMP and less than 6% of SMX appeared in dialysate. We conclude that peritoneal losses contribute insignificantly to TMP/SMX elimination during CAPD.

Administration, Oral↗
PubMed1989

Dietary restriction, tyramine, and the use of monoamine oxidase inhibitors.

The aim of this study is to provide clearer guidelines for rational, safe, and practical dietary restriction for use with monoamine oxidase inhibitors. Tyramine levels were assayed in over 100 of the controversial foods that have been associated with hypertensive reactions or reported to contain high levels of tyramine. Only a very limited number of foods appear to require absolute restriction. These include all aged cheeses, concentrated yeast extracts (e.g., Marmite), sauerkraut, and broad bean pods. Alcoholic beverages, including Chianti wine consumed in moderation, appear to be safe. Some aged meats contain relatively high levels of tyramine and require closer investigation.

Food Analysis↗
PubMed1989

Recombinant interleukin-2 therapy of systemic lupus erythematosus in the New Zealand black/New Zealand white mouse.

New Zealand Black/New Zealand White (NZB/W) mice, a model of systemic lupus erythematosus (SLE), have age-dependent loss of interleukin-2 (IL-2) production. To determine if replacement therapy would influence the course of autoimmune disease, we injected groups of NZB/W mice with low-dose (1,500 units/day) or high-dose (15,000 units/day) purified human recombinant IL-2. Parameters of active SLE and populations of splenocytes were not altered consistently by long-term treatment with either dose of IL-2.

Animals↗