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Biomedical subjects

S T Clark

Publications and source records attributed to S T Clark.

8 recordsLinked to original sources
PubMed2001

Empirical investigation of extreme single-particle behavior of nuclear quadrupole moments in highly collective A approximately 150 superdeformed bands.

The intrinsic quadrupole moment Q(0) of superdeformed rotational bands in A approximately 150 nuclei depends on the associated single-particle configuration. We have derived an empirical formula based on the additivity of effective quadrupole moments of single-particle orbitals that describes existing measurements from (142)Sm to (152)Dy. To further test the formula, the predicted Q(0) moments for two superdeformed bands in (146)Gd of 14.05 eb were confronted with a new measurement yielding 13.9+/-0.4 eb and 13.9+/-0.3 eb, respectively. This excellent agreement provides empirical evidence of extreme single-particle behavior in highly deformed, collective systems.

Journal Article↗
PubMed2001

A comparison of individual and family psychology of adolescents with chronic fatigue syndrome, rheumatoid arthritis, and mood disorders.

Chronic fatigue syndrome (CFS) is a controversial diagnosis with unknown cause. Adult studies indicate high rates of psychosocial dysfunction and psychiatric comorbidity. The authors compared three groups of pediatric patients selected by diagnosis-(1l) CFS (n = 15), (2) juvenile rheumatoid arthritis (n = 15), and (3) mood disorders (n = 15)-across many psychological measures. CFS subjects had dramatic elevation of the Somatic Complaints subscale (mean T score = 75), whereas the mood disorders group had higher externalizing scores (mean T score = 68) on the Child Behavior Checklist. The CFS subjects missed significantly more school compared with the two control groups. After the onset of CFS, 13 of 15 of the CFS patients required significant educational accommodation. Only 4 of the 15 CFS patients had an Axis I psychiatric diagnosis, as determined by the Computerized Diagnostic Interview for Children. Despite a low rate of psychiatric diagnosis in the CFS sample, these data attest to their psychosocial and school dysfunction.

Adolescent↗
PubMed1995

Gonadal function following chemotherapy for Hodgkin's disease: a comparative study of MVPP and a seven-drug hybrid regimen.

PURPOSE AND METHODS: Gonadal function was assessed in 89 patients after chemotherapy for Hodgkin's disease (HD). Thirty-seven patients had received mechlorethamine, vinblastine, prednisolone, and procarbazine (MVPP) and 52 patients, a hybrid combination of chlorambucil, vinblastine, prednisolone, procarbazine, doxorubicin, vincristine, and etoposide (ChIVPP/EVA). Fifty men (MVPP, n = 21; ChIVPP/EVA, n = 29) with a median age of 26 years (range, 16 to 54) and 39 women (MVPP, n = 16; ChIVPP/EVA, n = 23) with a median age of 30 years (range, 15 to 47) were studied at a median of 30 months (range, 4 to 83) following chemotherapy. RESULTS: Semen analysis showed azoospermia in 35 of 37 men, and increased serum follicle-stimulating hormone (FSH) levels in this group confirmed severe germinal epithelial damage. Analysis of pretreatment semen in 28 men showed azoospermia in one, oligospermia in four (sperm count < 20 x 10(6)/mL), and a normal sperm count in the remaining 23. In the women, 26 of 34 (76%) with a regular menstrual cycle before commencing chemotherapy became amenorrheic following treatment. Menses returned in 10 women, who had a median age of 25 years (range, 21 to 34), and there were two pregnancies in this group. In the other 16, with a median age of 36 years (range, 27 to 47), amenorrhea persisted and premature ovarian failure was confirmed by increased serum gonadotrophins and reduced estradiol (E2) concentrations. Of the original eight women in whom menses were maintained following treatment, two subsequently developed amenorrhea and the clinical and biochemical features of an early menopause. In total, 18 of 34 women (53%) required hormone replacement therapy for chemotherapy-induced ovarian failure. CONCLUSION: There was no statistically significant difference in the frequency or severity of gonadal dysfunction between MVPP- and ChIVPP/EVA-treated patients. We conclude that both of these chemotherapy schedules cause substantial damage to gonadal function in both sexes.

Adolescent↗
PubMed1994

Reduced bone mineral density in men following chemotherapy for Hodgkin's disease.

We have measured bone mineral density (BMD) in 29 men, mean age 35.0 (range 19.7-58.0) years, with testicular damage following MVPP or hybrid chemotherapy for Hodgkin's disease. Forearm cortical bone mineral content (BMC) and lumbar spine and femoral neck integral BMD were measured 3.4 (1.1-6.8) years after completion of chemotherapy, and results expressed as Z (standard deviation) scores. There was a significant reduction in forearm cortical BMC (median BMC 1.727 g cm-1, median Z-score -0.8, P < 0.0005), in lumbar spine integral BMD (median BMD 1.141 g cm-2, median Z-score -0.6, P < 0.0005) and in femoral neck integral BMD (median BMD 0.991 g cm-2, median Z-score -0.4, P < 0.05). There was no significant correlation between Z-score and time elapsed since completion of chemotherapy, and no significant difference in Z-score according to type of chemotherapeutic regimen or number of cycles of chemotherapy received. In conclusion, men who are in complete remission following treatment of Hodgkin's disease have reduced cortical and trabecular BMD. Possible causes include mild hypogonadism secondary to chemotherapy-induced impairment of Leydig cell function, a direct effect of chemotherapy on bone, an effect of high-dose glucocorticoid on bone or an effect of Hodgkin's disease per se.

Adult↗
PubMed1989

Comparison of the mastoid to vertex and mastoid to high forehead electrode arrays in recording auditory evoked potentials.

The ipsilateral mastoid to vertex and ipsilateral mastoid to high forehead electrode arrays were found to have equal efficacy in recording the auditory brain stem and middle latency responses in both open and closed filtered conditions. It is concluded that the ipsilateral mastoid to high forehead electrode array is a valid clinic alternative for use in evoked response testing.

Audiometry, Evoked Response↗
PubMed1987

Evidence for depressed humoral immunity to Pneumocystis carinii in homosexual males, commercial plasma donors, and patients with acquired immunodeficiency syndrome.

Heterosexual controls were found to have significantly higher titers of immunoglobulin G antibody to Pneumocystis carinii than did patients with the acquired immunodeficiency syndrome (AIDS) and P. carinii pneumonitis, human immunodeficiency virus (HIV) antibody-positive or -negative homosexual male "gay bar" patrons, and HIV antibody-positive or -negative commercial plasma donors. The T-helper/T-suppressor lymphocyte ratios of HIV antibody-negative homosexual male gay bar patrons were slightly depressed (mean = 1.31 +/- 0.54) compared with those of heterosexual controls (mean = 1.79 +/- 0.32). In addition to other recognized factors, preexisting humoral as well as cell-mediated immune deficits before infection with HIV may help to explain the prevalence of and morbidity and mortality associated with P. carinii pneumonitis in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Implementation and cost analysis of a syringe pump system for intermittent i.v. drug delivery.

Implementation of a syringe pump system for delivery of intermittent i.v. drug doses in a 452-bed teaching hospital is described; the system was evaluated for cost effectiveness one year after implementation. Drugs to be administered by syringe pump were diluted to concentrations recommended for i.v. push administration and then administered over 22-30 minutes. For batch preparation of more than 100 syringe doses, an automated dispensing pump was used. Before the syringe pump system was implemented hospitalwide, costs were predicted on the basis of data from the pharmacy's computerized i.v. administration records. In the first year after hospitalwide implementation of the system, 4687 patients received 113,898 doses of intermittent i.v. medications by syringe pump; this represented approximately 73% of all intermittent i.v. doses. The remaining doses were dispensed in minibags, and no substantial problems resulted from concurrent use of both systems. Based on current contract prices, use of the syringe pump system resulted in savings of more than +79,000 during the first year. Implementation of a syringe pump system for administration of most intermittent i.v. medications resulted in substantial cost savings.

Anti-Bacterial Agents↗