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Biomedical subjects

S Parnell

Publications and source records attributed to S Parnell.

7 recordsLinked to original sources
PubMed2002

Socioeconomic deprivation and asthma prevalence and severity in young adolescents.

This study used the international study of asthma and allergies in childhood (ISAAC) to investigate the association between asthma and socioeconomic deprivation among young adolescents in Cape Town, South Africa. The completed ISAAC written and video questionnaires of 4,706 13-14-yr-old school pupils were used. The prevalence of asthma symptoms was analysed by a local index of socioeconomic deprivation, based on residential location and defined on a 10-category scale from least to most deprived. Linear trends were examined visually and the prevalence odds ratio was used to summarize overall trends. In general, the least socioeconomically deprived pupils reported higher prevalences of asthma symptoms "ever" and "in the last 12 months". In contrast, the most socioeconomically deprived pupils reported higher asthma-symptom occurrence monthly or more frequently in the previous 12 months. A subgroup of pupils from low-income areas commuting to better-off schools showed the highest symptom prevalences. The findings are consistent with a model in which an increase in the incidence of asthma is driven by factors associated with improved social circumstances, whereas severity is determined by factors associated with poverty. The impact of social mobility on asthma, including reporting of symptoms, deserves closer study.

Adolescent↗
PubMed2001

Notch ligand-bearing thymic epithelial cells initiate and sustain Notch signaling in thymocytes independently of T cell receptor signaling.

Thymic epithelial cells are specialized to play essential roles at multiple stages of T cell development in the thymus, yet the molecular basis of this specialization is largely unknown. Recently, the Notch family of transmembrane proteins has been implicated in thymocyte development. Such proteins interact with cell surface proteins of the Delta-like and Jagged families. It is known that Notch ligands are expressed intrathymically, and that Notch signaling is regulated by Notch ligands expressed on either the same or third-party cells. However, functional analysis of Notch ligand expression, and elucidation of the mechanism of Notch ligand signaling in thymocyte development, are unclear. Here, we find that Notch ligand expression in the thymus is compartmentalized, with MHC class II(+) thymic epithelium, but not thymocytes nor dendritic cells, expressing Jagged-1, Jagged-2 and Delta-like-1. We also provide evidence that contact with Notch ligands on thymic epithelium is necessary to activate and sustain Notch signaling in thymocytes, and that this can occur independently of positive selection induction. Our data suggest that Notch ligand expression by thymic epithelium may partly explain the specialization of these cells in supporting thymocyte development, by regulating Notch activation via an inductive signaling mechanism independently of signaling leading to positive selection.

Animals↗
PubMed1999

Specialized ability of thymic epithelial cells to mediate positive selection does not require expression of the steroidogenic enzyme p450scc.

Thymic epithelial cells are uniquely efficient in mediating positive selection, suggesting that in addition to providing peptide/MHC complexes for TCR ligation, they may also provide additional support for this process. Recent studies have shown that although engagement of either the TCR or glucocorticoid (GC) receptors can individually induce apoptosis in thymocytes, together these signals are mutually antagonistic. This had led to the suggestion that local GC production by thymic epithelial cells, by opposing TCR signaling for apoptosis, provides the basis of the ability of these cells to mediate thymocyte positive selection. In this paper we have examined this possibility directly and shown that highly purified cortical epithelial cells, which have the functional ability to mediate positive selection in reaggregate cultures, do not express mRNA for the key steroidogenic enzyme P405scc. Thus we conclude that the ability of thymic epithelial cells to support positive selection does not rely on their ability to produce GC. However, we find that P450scc mRNA is up-regulated in thymocytes on the initiation of positive selection, raising the possibility that any local protective effect of steroid production is mediated at the level of thymocytes themselves.

Animals↗
PubMed1998

Intervention for medical students: effective infection control.

Needlestick injuries, which lead to the transmission of hepatitis B, hepatitis C, and the AIDS virus, are a potentially serious threat to students during their clinical experiences. Exposure to infectious diseases, blood, and hazardous body fluids is one of the most frequently reported injury events by medical students at a health science center in the southwestern region of the United States. This study was conducted to determine the effectiveness of a customized intervention about infection control for second-year medical students (N = 200). Preparation for the intervention included a needs assessment, which included both qualitative and quantitative research methods that incorporated input from fourth-year medical students, medical staff members, and local hospital infection control specialists. The intervention included a pretest, a lecture, a demonstration of standard precautions and infection control procedure with 2 clinical scenarios, an exercise on proper handwashing, and a posttest. The evaluation of the intervention demonstrated a significant increase in posttest knowledge scores about infection control (from 12.6 +/- 2.1 pretest to 16.5 +/- 1.8 posttest, P < .001). Medical students showed a significant knowledge increase about infection control after participating in the intervention . Thus we recommend that all medical colleges and universities develop and evaluate a similar customized intervention for their medical students.

Adult↗
PubMed1997

Blood pressure measurement in the hemodialysis setting.

Blood pressure measurement is an important component of the care of the hemodialysis patient. Invasive methods, as used in the intensive care setting, are the most accurate. In the ambulatory setting, noninvasive methods, such as palpitation, auscultation, and oscillometry, are used. When care is taken to avoid operator error, these techniques should yield results that are sufficiently accurate for clinical use. All new devices should be validated for accuracy.

Auscultation↗