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Biomedical subjects

N Bock

Publications and source records attributed to N Bock.

14 recordsLinked to original sources
PubMed2006

Tuberculosis case finding and preventive therapy in an HIV voluntary counseling and testing center in Uganda.

SETTING: A large, urban human immunodeficiency virus (HIV) voluntary counseling and testing (VCT) center in Kampala, Uganda. OBJECTIVE: Tuberculosis (TB) is a leading cause of morbidity and mortality in persons with HIV infection in sub-Saharan Africa. Intensified TB case finding and use of isoniazid preventive therapy (IPT) for latent infection reduces the burden of TB, but few programs have been implemented due to concerns about feasibility. DESIGN: Retrospective evaluation of a TB case finding and IPT program. RESULTS: Over a 25-month period, 6305 patients newly diagnosed with HIV infection underwent evaluation: 293 (5%) had TB disease; 1955 (37%) patients were not eligible for preventive therapy because they lived > 20 km away, had advanced HIV disease, or had previously had TB. Of 3366 who had a tuberculin skin test (TST) placed, 2548 (76%) had the TST read; 894 (35%) of these were positive. Of 506 persons who started treatment, 335 (66%) completed it. CONCLUSION: This unique program was feasible, detected a high proportion of undiagnosed TB, and successfully treated persons with latent infection. Expanding access to HIV VCT as well as collaboration between HIV/ AIDS and TB programs can increase the proportion of HIV-infected persons who can benefit from these programs.

Adolescent↗
PubMed2001

Biodegradable polymer/hydroxyapatite composites: surface analysis and initial attachment of human osteoblasts.

Biodegradable polymer/hydroxyapatite (HA) composites have potential application as bone graft substitutes. Thin films of polymer/HA composites were produced, and the initial attachment of primary human osteoblasts (HOBs) was assessed to investigate the biocompatibility of the materials. Poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLA) were used as matrix materials for two types of HA particles, 50-microm sintered and submicron nonsintered. Using ESEM, cell morphology on the surfaces of samples was investigated after 90 min, 4 h, and 24 h of cell culture. Cell activity and viability were assessed after 24 h of cell culture using Alamar blue and DNA assays. Surface morphology of the polymer/HA composites and HA exposure were investigated using ESEM and EDXA, respectively. ESEM enabled investigation of both cell and material surface morphology in the hydrated condition. Combined with EDXA it permitted chemical and visual examination of the composite. Differences in HA exposure were observed on the different composite surfaces that affected the morphology of attached cells. In the first 4 h of cell culture, the cells were spread to a higher degree on exposed HA regions of the composites and on PLA than they were on PCL. After 24 h the cells were spread equally on all the samples. The cell activity after 24 h was significantly higher on the polymer/HA composites than on the polymer films. There was no significant difference in the activity of the cells on the various composite materials. However, cells on PCL showed higher activity compared to those on PLA. A polymer surface exhibiting "point exposure" of HA appeared to provide a novel and favorable substrate for primary cell attachment. The cell morphology and activity results indicate a favorable cell/material interaction and suggest that PLA and PCL and their composites with HA may be candidate materials for the reconstruction of bony tissue. Further investigations regarding long-term biomaterial/cell interactions and the effects of acidic degradation products from the biodegradable polymers are required to confirm their utility.

Bone Substitutes↗
PubMed2001

The Pars tuberalis of the monkey (Macaca fascicularis) hypophysis: cell types and hormone expression.

The pars tuberalis (Pt) of most mammalian species contains specific cells which are structurally and functionally different from the pars distalis (Pd) cells. Pt-specific cells possess melatonin receptors and reveal morphological changes dependent on the duration of the photoperiod. Furthermore, in hamsters the transmission of photoperiodic stimuli to the endocrine system is influenced by melatonin, an effect which is likely to be mediated by Pt-specific cells. In monkeys, however, only little is known about this cell type. Therefore, we studied the ultrastructural differentiation of Pt-specific cells and describe the expression of different hormones and their mRNA by immunohistochemistry and in situ hybridization. Apparently the Pt consists of (1) cells similar to gonadotropic cells of the Pd, (2) folliculostellate cells and (3) a cell population which is morphologically and functionally clearly distinct from all other cell types found in the Pd. Morphologically they resemble the Pt-specific cells found in other species. Regarding the expression of secretory products there is evidence that they transcribe and translate the beta-TSH subunit. Although there is a strong signal for the mRNA of the common alpha-chain, protein staining is much weaker. POMC mRNA is expressed in the Pt while there is no evidence for PRL mRNA. The present results lead to the conclusion that the Pt of the monkey contains Pt-specific cells which express different hormonal subunits as was already shown for other species. In context with previous findings of melatonin receptors in the monkey Pt further investigations are necessary to establish the possible role of Pt-specific cells in the photoperiod-dependent generation of endocrine rhythms.

Animals↗
PubMed2001

Children with comorbid attention-deficit-hyperactivity disorder and tic disorder: evidence for additive inhibitory deficits within the motor system.

For children with attention-deficit-hyperactivity disorder (ADHD) or tic disorder (TD), we recently reported deficient inhibitory mechanisms within the motor system by using transcranial magnetic stimulation. These deficits--stated as reduced intracortical inhibition in ADHD and shortened cortical silent period in TD--could be seen as neurophysiological correlates of motor hyperactivity and tics, respectively. To investigate neurophysiological aspects of comorbidity, we measured motor system excitability for the first time also in children with combined ADHD and TD. The findings of a reduced intracortical inhibition as well as a shortened cortical silent period in these comorbid children provide evidence for additive effects at the level of motor system excitability.

Adolescent↗
PubMed2000

Age-associated changes in the densities of presynaptic monoamine transporters in different regions of the rat brain from early juvenile life to late adulthood.

The binding parameters of highly selective ligands of serotonin (5-HT) transporters ([3H]paroxetine), noradrenaline (NE) transporters ([3H]nisoxetine), and of dopamine (DA) transporters ([3H]GBR-12935) were determined on membrane preparations from frontal cortex, striatum, midbrain and brain stem of Wistar rats on postnatal days 25, 50, 90 and 240, i.e., from the time of weaning till late adulthood. No age-dependent alterations in the affinity-parameters (K(D)-values) of all three monoamine transporters were observed. Age-associated changes in B(max)-values of the binding of all three specific ligands were most pronounced in the phylogenetically younger, late maturing brain regions (frontal cortex, striatum). Most likely, these changes reflect age-related changes in 5-HT, NE and DA-innervation densities. In the frontal cortex, 5-HT-transporter density increased steadily from weaning (day 25) till late adulthood, whereas the density of NE-transporters was highest at weaning, declined till puberty (day 50) and remained at this level until old age. DA-transporter density in the frontal cortex was not reliably measurable by [3H]GBR-binding assays. In the striatum, DA-transporter density increased till puberty and declined thereafter considerably and steadily to about one-fourth of the pubertal values at old age. No such age-associated changes in DA-transporter density were seen in the midbrain. Densities of 5-HT and NE remained at the level reached already at weaning until old age in the striatum, midbrain and brain stem. These findings provide the first comprehensive description of the normally occurring changes in the densities of all three presynaptically located monoamine transporters in the rat brain throughout the life span from weaning to late adulthood.

Aging↗
PubMed1999

Comparable specificity of 2 commercial tuberculin reagents in persons at low risk for tuberculous infection.

CONTEXT: One or both commercial tuberculin skin test reagents (Aplisol and Tubersol) may have a high rate of false-positive reactions. OBJECTIVE: To compare the reaction size and specificity of skin testing with Aplisol, Tubersol, and the standard purified protein derivative (PPD-S1). DESIGN: Double-blind trial, conducted between May 14, 1997, and October28, 1997, in which each individual received 4 tuberculin skin reagents at sites assigned at random. SETTING: Health departments and universities in 6 US cities. PARTICIPANTS: A total of 1555 persons at low risk of latent tuberculosis infection. INTERVENTION: Simultaneous skin tests with Aplisol, Tubersol, PPD-S1, and either a second PPD-S1 or PPD-S2 (a proposed new standard). MAIN OUTCOME MEASURE: Reaction size at each injection site measured by 2 investigators blinded to type of reagent. RESULTS: Aplisol produced slightly larger reactions than Tubersol, but this difference did not significantly change skin test interpretation. The mean +/- SD reaction sizes were 3.4+/-4.2 mm with Aplisol, 2.1+/-3.2 mm with Tubersol, and 2.5+/-3.6 mm with PPD-S1. Assuming that all participants were uninfected and using a 10-mm cutoff, the specificities of the tests were high: Aplisol, 98.2%; Tubersol, 99.2%; and PPD-S1, 98.9%. Significant variability was not detected in interobserver, host, and lot-to-lot reagent comparisons. CONCLUSION: Using a cutoff of at least 10 mm, testing with 3 different PPD reagents resulted in similar numbers of uninfected persons being correctly classified.

Adult↗
PubMed1996

Acceptance of isoniazid preventive therapy by health care workers after tuberculin skin test conversion.

OBJECTIVE: To examine health care workers' (HCWs') acceptance of and adherence to isoniazid preventive therapy in the setting of a comprehensive tuberculin skin-testing program. DESIGN: Descriptive case series. SETTING: University-affiliated inner-city public hospital in Atlanta, Ga. PARTICIPANTS: A total of 125 HCWs (91 hospital employees and 34 house staff or medical students [the physician group]) who had a positive tuberculin skin test between July 1992 and January 1994 and were offered isoniazid preventive therapy. INTERVENTIONS: Health care workers with a recent tuberculin skin test conversion were required to have a chest x-ray performed and see a physician and were encouraged but not required to undergo preventive therapy. MAIN OUTCOME MEASURES: Acceptance and initiation of preventive therapy with isoniazid by HCWs, completion of at least 6 months of preventive therapy, and differences between the employee and physician groups. RESULTS: All 125 HCWs with a recent positive tuberculin skin test had a chest radiograph performed, 123 (98.4%) saw a physician, and 105 (84%) initiated preventive therapy. Sixty-nine (66%) of the 105off HCWs who initiated preventive therapy (55% of the 125 total) completed at least 6 months of isoniazid therapy. More of the physician group than of the employee group completed preventive therapy (25 of 34 [74%] vs 44 of 91 [48%], respectively; P<.01). Of the 36 HCWs who started but did not complete preventive therapy, 12 discontinued therapy because of an adverse drug effect and 24 were nonadherent. CONCLUSIONS: Acceptance of tuberculosis preventive therapy by HCWs was high in the setting of a comprehensive tuberculin skin-testing program, and completion of therapy was much higher in the physician group than in previously reported series.

Adult↗
PubMed1992

Rotating shift work, sleep, and accidents related to sleepiness in hospital nurses.

A hospital-based survey on shift work, sleep, and accidents was carried out among 635 Massachusetts nurses. In comparison to nurses who worked only day/evening shifts, rotators had more sleep/wake cycle disruption and nodded off more at work. Rotators had twice the odds of nodding off while driving to or from work and twice the odds of a reported accident or error related to sleepiness. Application of circadian principles to the design of hospital work schedules may result in improved health and safety for nurses and patients.

Accidents, Occupational↗
PubMed1988

Effects of ambient ozone on respiratory function in active, normal children.

Respiratory functions were measured on a daily basis by spirometry over a period of 4 wk at a summer camp at Fairview Lake in northwestern New Jersey. Fifty-three boys and 38 girls 8 to 15 yr of age participated in the study on at least 7 days; 37 children were in residence for 4 wk, 34 for the first 2 wk only; and 20 for the last 2 wk. There were 72 whites, 15 blacks, 3 Asians, and 1 Hispanic in the study group. Multiple regression analyses indicated that the O3 concentration in the previous hour, the cumulative daily O3 exposure during the hours between 9 A.M. and the function measurement, ambient temperature, and humidity were the most explanatory environmental variables for daily variations in function, with the 1 - h O3 concentration having the strongest influence. Linear regressions were performed for each child between O3 concentration and function, and all average slopes were significantly negative (p less than 0.05) for FVC, FEV1, PEFR, and FEF25-75 for all children, and for boys and girls separately. Comparable results were obtained in data subsets (i.e., children studied during the first or second 2 wk only, and for data sets truncated at O3 less than 80 and O3 less than 60 ppb). The average regression slopes (+/- SE) for FVC and FEV1, respectively, were -1.03 +/- 0.24 and -1.42 +/- 0.17 ml/ppb, whereas for PEFR and FEF25-75 they were -6.78 +/- 0.73 and -2.48 +/- 0.26 ml/s/ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Expression of the mismatch repair protein hMSH2 in carcinoma in situ and invasive cancer of the breast.

BACKGROUND: Dysregulations in the mechanism of DNA-repair are contributed to tumorgenesis and tumorprogression in human cancer. The mismatch repair gene hMSH2 encodes a protein, which recognizes and binds to mismatch-sequences of the DNA. METHODS: Using immunohistochemical techniques hMSH2 expression was analyzed in invasive cancer (n = 85) and in situ carcinoma (n = 34) of the breast. RESULTS: The percentage of hMSH2 positive cases was significantly (p = 0.0001) decreased in invasive cancer as compared to in situ carcinomas. There was an association of hMSH2 expression with parameters of unfavorable prognosis, such as lymph node involvement (p = 0.03), higher degree of malignancy (p = 0.05) and higher proliferative activity (p = 0.05). CONCLUSIONS: During development from in situ to invasive cancer of the breast, hMSH2 expression seems to be downregulated. However, in invasive cancer, hMSH2 expression seems to be associated with tumor progression. This could be explained by the fact that enhanced proliferation of tumor cells results in increased mistakes within DNA replication procedures.

Adenocarcinoma↗