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Biomedical subjects

K Sampson

Publications and source records attributed to K Sampson.

11 recordsLinked to original sources
PubMed2004

Phallacidin stains the mitotic spindle of the diatom Pinnularia spp.

Mitotic spindles of the diatom Pinnularia viritiformis stained with the fluorescent actin-labelling reagent bodipyphallacidin revealed actin among the chromosomes and extending along the spindle to the poles. This is the first report of actin's presence within spindles of this ecologically important group of organisms. Since diatom mitoses have a number of marked differences compared to that of many other eukaryotes (Int Rev Cytol 128 (1991) 63; Cell 14 (1978) 455), the present observations substantially extend the diversity of mitotic spindle types in which there is evidence of spindle actin.

Actins↗
PubMed2001

Phallacidin stains the kinetochore region in the mitotic spindle of the green algae Oedogonium spp.

We found previously that in living cells of Oedogonium cardiacum and O. donnellii, mitosis is blocked by the drug cytochalasin D (CD). We now report on the staining observed in these spindles with fluorescently actin-labeling reagents, particularly Bodipy FL phallacidin. Normal mitotic cells exhibited spots of staining associated with chromosomes; frequently the spots appeared in pairs during prometaphase-metaphase. During later anaphase and telophase, the staining was confined to the region between chromosomes and poles. The texture of the staining appeared to be somewhat dispersed by CD treatment but it was still present, particularly after shorter (< 2 h) exposure. Electron microscopy of CD-treated cells revealed numerous spindle microtubules (MTs); many kinetochores had MTs associated with them, often laterally and some even terminating in the kinetochore as normal, but the usual bundle of kinetochore MTs was never present. As treatment with CD became prolonged, the kinetochores became shrunken and sunk into the chromosomes. These results support the possibility that actin is present in the kinetochore of Oedogonium spp. The previous observations on living cells suggest that it is a functional component of the kinetochore-MT complex involved in the correct attachment of chromosomes to the spindle.

Actins↗
PubMed2001

Inhibition of mast cell tryptase by inhaled APC 366 attenuates allergen-induced late-phase airway obstruction in asthma.

BACKGROUND: APC 366, a selective inhibitor of mast cell tryptase, has been shown to inhibit antigen-induced early asthmatic response (EAR), late asthmatic response (LAR), and bronchial hyperresponsiveness (BHR) in a sheep model of allergic asthma. OBJECTIVE: The purpose of this study was to investigate the effects of APC 366 on antigen-induced EAR, LAR, and BHR in mild atopic asthmatics not on any anti-inflammatory therapy. METHODS: Sixteen mild atopic asthmatics, each with a demonstrable antigen-induced EAR, LAR, and BHR to histamine, were recruited into this randomized, double-blinded, crossover study. APC 366 (5 mg)/placebo was administered by aerosol inhalation 3 times per day on treatment days 1 through 4. Allergen challenge was carried out on day 4. Histamine challenge was performed the following morning, 1 hour after final dosing. RESULTS: Subjects were shown to have a significantly smaller overall mean area under the curve for the LAR (P =.012) and mean maximum fall in FEV(1) for the LAR (P =.007) after pretreatment with APC 366 in comparison with placebo. No significant effects on BHR were demonstrable. Although the EAR was reduced by 18% after treatment with APC 366 in comparison with placebo, this was not statistically significant. CONCLUSION: Short-term repeated administration of APC 366 significantly reduced the magnitude of antigen-induced LAR in atopic asthmatics, which supports the role of mast cell tryptase in the pathophysiology of the LAR.

Administration, Inhalation↗
PubMed2001

Academic, motivational, and emotional correlates of adolescent dating.

This study is an examination of the relationship between dating status and academic achievement, academic motivation, depression, and self-esteem; it is an investigation of the differential effects wielded by gender and age (grade level) of the dating adolescent in each of these domains. Participants were a relatively large gender-balanced adolescent group (N = 380) from Grades 8, 10, and 12. Dating status was studied first as a binary variable (frequent versus infrequent dating) and second as a dating spectrum, including steady, frequent, and infrequent dating. Results showed that adolescents who dated frequently (more than once or twice a month), whether they were boys or girls, relatively young (8th grade) or more mature (l0th and 12th grades), exhibited consistently and significantly lower levels of academic achievement and academic motivation and higher levels of depressive symptoms. There were no significant effects of dating status on global self-esteem, but, as hypothesized, subscale analyses revealed important subscale-differentiated effects.

Adolescent↗
PubMed1999

Regional teaching improvement programs for community-based teachers.

PURPOSE: Community-based clinical teachers provide an important cadre of faculty for medical education. This study was designed to examine the feasibility and value of an American College of Physicians-sponsored regional teaching improvement program for community-based teachers. SUBJECTS AND METHODS: We conducted five regional (Connecticut, New Hampshire/Vermont, New York, Ohio, and Virginia) 1- to 2-day teaching-improvement workshops for 282 faculty (49% community based, 51% university based). The workshops were conducted by regional facilitators trained by the Stanford Faculty Development Program using large group and small group instructional methods to teach participants a framework for analyzing teaching, to increase their repertoire of teaching behaviors, to define personal teaching goals, and to identify the educational needs of their teaching site. Participants used Likert ratings [1 (low) to 5 (high) scale] to assess workshop quality, facilitator effectiveness, and rewards for and barriers to teaching in their clinics. Using retrospective pre- and postintervention ratings, participants also assessed workshop impacts on teacher knowledge, attitudes, and skills. Finally, participants completed open-ended questions to identify recommended changes to improve their clinic as an educational site for students and residents. RESULTS: At all sites, participants evaluated the program as highly useful (4.6 +/- 0.6, mean +/- SD). Participants' ratings indicated that the program had a positive effect on their knowledge of teaching principles (4.0 +/- 0.9), an increase in their teaching ability (P <0.001), and an increase in their sense of integration with their affiliated institution (P <0.001). CONCLUSIONS: Regional training of university and community faculty can be an effective way of promoting the improvement of teaching and the collaboration between community-based teachers and academic centers. National physician organizations and regionally based facilitators can provide important resources for the delivery of such training.

Adult↗
PubMed1996

Ethnic differences in women with HIV infection in Britain and Ireland. The study group for the mrc collaborative study of HIV infection in women.

OBJECTIVE: To examine ethnic differences in the socio-epidemiological and clinical characteristics of a cohort of women with HIV infection in Britain and Ireland. DESIGN AND METHODS: Analysis of baseline data (ethnic group, sexual history, likely route of HIV infection, reasons for HIV testing and first AIDS-defining disease) from 400 women with HIV infection recruited into a cohort study from 15 genitourinary medicine/HIV clinics in Britain and Ireland. RESULTS: Sixty-five per cent of women were white and 29% black African. Their median number of lifetime sexual partners was seven and three, respectively (P < 0.001). Ninety-three per cent of black African and 43% of white women were probably infected through sexual intercourse. Injecting drug use was the most likely route of infection in 55% of white women, but none of the black African women. Perceived risk (33%) or investigation of symptoms (26%) were the most common reasons for HIV testing. Seven per cent of white women and 16% of black African women (P < 0.001) had AIDS when HIV infection was diagnosed. The distribution of first AIDS-defining diagnoses differed (P = 0.001) by ethnic group. For white women, the most common disease was Pneumocystis carinii pneumonia; for black African women it was pulmonary tuberculosis. CONCLUSION: There are important differences between black African and white women in sexual history and route of transmission, disease stage at diagnosis and pattern of AIDS-defining diseases.

AIDS Serodiagnosis↗
PubMed1995

Physical and functional interaction of the Epstein-Barr virus BZLF1 transactivator with the retinoic acid receptors RAR alpha and RXR alpha.

Epstein-Barr virus (EBV) reactivation, indicated by induction of EBV early antigens from latently infected lymphoid cell lines by phorbol esters, is inhibited by retinoic acid (RA). Viral reactivation, which is triggered by the immediate-early BZLF-1 (Z) viral gene product, is repressed by retinoic acid receptors (RARs) RAR alpha and RXR alpha. These proteins negatively regulate Z-mediated transactivation of the promoter for an EBV early gene product, early antigen-diffuse (EaD). Here we confirm a direct physical interaction between the AP1-like protein Z and RXR alpha and map the domains of interaction in the Z protein and RXR alpha. The domain required for homodimerization of Z is separate from that required for its interaction with RXR alpha. Z also has the effect of repressing activation of an RAR-responsive cellular promoter (BRE). Point mutants in the dimerization domain of Z unable to interact with RXR alpha do not repress RXR alpha-mediated transactivation of BRE, the promoter for RAR beta, which suggests that interaction between the two proteins is required for this repressor effect. The domain of RXR alpha required for interaction with Z has been mapped, and is again separate from that required for homodimerization. These results indicate that a 'cross-coupling' or direct interaction between Z and RAR alpha and RXR alpha can modulate the reactivation of latent EBV infection and suggest that, reciprocally, the viral protein Z may influence cellular regulatory pathways.

Amino Acid Sequence↗
PubMedDate not supplied

Activity-based resource allocation: a system for predicting nursing costs.

As hospital-based managers are being confronted with changing patterns of reimbursement, ranging from revenue generating to cost management, it is imperative that hospitals know the exact nursing costs associated with the actual care delivered to specific patients. Nursing care has traditionally been bundled into the room rate for patients. This approach is extremely limiting when facilities are negotiating per diem rates and capitated rate contracts. At Braintree Hospital Rehabilitation Network, the nursing department has developed and implemented an activity-based management system to determine the actual cost of nursing care provided to each patient. This approach, which differentiates nursing costs accurately by diagnostic group and by intensity of nursing care, has contributed to the hospital's success in negotiating individual patient contracts with insurers in the managed care environment that increasingly focuses on costs and outcomes. Another result has been to enhance the accuracy of the network's cost accounting system.

Cost Allocation↗