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Biomedical subjects

Deborah Williams

Publications and source records attributed to Deborah Williams.

6 recordsLinked to original sources
PubMed2003

Low arterial compliance in young African-American males.

Hypertension remains a common public health challenge because of its prevalence and increase in co-morbid cardiovascular diseases. Black males have disproportionate pathophysiological consequences of hypertension compared with any other group in the United States. Alterations in arterial wall compliance and autonomic function often precede the onset of disease. Accordingly, our purpose was to investigate whether differences exist in arterial compliance and autonomic function between young, healthy African-American males without evidence of hypertension and age- and gender-matched non-African-American males. All procedures were carried out noninvasively following rest. Arterial compliance was calculated as the integrated area starting at the well-defined nadir of the incisura of the dicrotic notch to the end of diastole of the radial artery pulse wave. Power spectral analysis of heart rate and blood pressure variability provided distributions representative of parasympathetic and sympathetic modulations and sympathovagal balance. Baroreflex sensitivity (BRS) was calculated using the sequence method. Thirty-two African-American and twenty-nine non-African-American males were comparable in anthropometrics and negative family history of hypertension. t-Tests revealed lower arterial compliance (5.8 +/- 2.4 vs. 8.6 +/- 4.0 mmHg. s; P = 0.0017), parasympathetic modulation (8.9 +/- 1.1 vs. 9.7 +/- 1.1 ln ms2; P = 0.0063), and BRS (13.7 +/- 7.3 vs. 21.1 +/- 8.5 ms/mmHg; P = 0.0007) and higher sympathovagal balance (2.9 +/- 3.2 vs. 1.5 +/- 1.1; P = 0.03) in the African-American group. In summary, differences exist in arterial compliance and autonomic balance in African-American males. These alterations may be antecedent markers of disease and valuable in the detection of degenerative cardiovascular processes in individuals at risk.

Adult↗
PubMed2003

Single primer amplification (SPA) of cDNA for microarray expression analysis.

The potential of expression analysis using cDNA microarrays to address complex problems in a wide variety of biological contexts is now being realised. A limiting factor in such analyses is often the amount of RNA required, usually tens of micrograms. To address this problem researchers have turned to methods of improving detection sensitivity, either through increasing fluorescent signal output per mRNA molecule or increasing the amount of target available for labelling by use of an amplification procedure. We present a novel DNA-based method in which an oligonucleotide is incorporated into the 3' end of cDNA during second-strand cDNA synthesis. This sequence provides an annealing site for a single complementary heel primer that directs Taq DNA polymerase amplification of cDNA following multiple cycles of denaturation, annealing and extension. The utility of this technique for transcriptome-wide screening of relative expression levels was compared to two alternative methodologies for production of labelled cDNA target, namely incorporation of fluorescent nucleotides by reverse transcriptase or the Klenow fragment. Labelled targets from two distinct mouse tissues, adult liver and kidney, were compared by hybridisation to a set of cDNA microarrays containing 6500 mouse cDNA probes. Here we demonstrate, through a dilution series of cDNA derived from 10 micro g of total RNA, that it is possible to produce datasets comparable to those produced with unamplified targets with the equivalent of 30 ng of total RNA. The utility of this technique for microarray analysis in cases where sample is limited is discussed.

Animals↗
PubMed2002

Aerobic exercise attenuates an exaggerated exercise blood pressure response in normotensive young adult African-American men.

An exaggerated exercise blood pressure response (EEBPR) may be associated with an increased risk of hypertension. We hypothesized that aerobic exercise training can decrease EEBPR and the risk for hypertension by decreasing arterial resistance. We studied the effects of aerobic training on the submaximal exercise blood pressure (BP) of eight normotensive young adult African-American men with an EEBPR. Subjects were trained on a stationary bicycle at an intensity of 70% peak oxygen uptake (VO2peak), for 30 min, three times per week, for 8 weeks. BP, heart rate, cardiac output (CO), stroke volume (SV) and total peripheral vascular resistance (TPR) were measured at rest and during submaximal exercise at a work intensity of 50% VO2peak. Significance of the training effects were evaluated by comparing the pre- and post-training measures (t-test, p < 0.05). A 15% post-training increase in VO2peak (34.6 +/- 1.4 to 40 +/- 1.4 ml/kg/min) and a 9.5 ml post-training increase in mean resting stroke volume were found. A 16.2 mmHg decrement in mean systolic BP, an 11.5 mmHg decrement in mean diastolic BP, a 120 dyne/s/cm5 decrement in TPR and a 1.2 l/min increase in CO were detected during the post-training submaximal exercise tests. These results suggest that reductions in TPR may attenuate the EEBPR of normotensive African-American males following an 8-week training regimen of stationary bicycling at 70% VO2peak. Aerobic exercise training may, therefore, reduce the risk of hypertension in normotensive African-American males by the mechanism of a reduction in TPR. Because of the limited number of subjects, the results of this study should be interpreted cautiously pending confirmation by a larger controlled trial.

Adolescent↗
PubMed2002

Survival benefit from calcium channel blockers in elderly blacks following acute myocardial infarction.

BACKGROUND: Calcium channel blockers (CCBs) have been used in elderly survivors of acute myocardial infarctions (AMI) and have been found to be safe in this setting. While the elderly have increased mortality following AMI, an ethnic disparity exists, with elderly African Americans having the highest mortality. It is proposed that much of the increased mortality in elderly African Americans may be related to their greater incidence of risk factors at the time of AMI, particularly hypertension. We proposed that elderly African Americans would receive survival benefits from the blood pressure lowering effects of CCBs. METHODS: We analyzed the Cooperative Cardiovascular Project (CCP) database to evaluate the impact of CCBs on survival in elderly patients with AMI. This database comprises patients admitted to US hospitals during 1994-1995 with a diagnosis of acute myocardial infarction. A retrospective chart analysis was performed to identify patients aged 65 years or older admitted with ICD-9 code 410 for acute myocardial infarction. Data were analyzed for trends. RESULTS: Of all elderly AMI admissions, 144,233 were Whites, and 9,906 were Blacks. Hypertension was common in both Whites and Blacks, 60.4% and 79.1%, P<.001, respectively. Calcium channel blockers were used with 27.3% of Whites, and 31.2% of Blacks, P<.001. Blacks had a lower 2-year survival rate, regardless of CCB status, with a 55.7% 2-year survival rate, compared to a 51% 2-year survival rate in Whites. However, in both Blacks and Whites, 2-year survival improved with CCB treatment to a 71.2% 2-year survival rate in Whites and a 68.5% 2-year survival rate in Blacks. Subset analysis by type of CCB demonstrated better survival rates with both dihydropyridine and non-dihydropyridine CCBs, compared to no CCBs, although there was a survival trend favoring non-dihydropyridine CCBs. CONCLUSIONS: Elderly Blacks had a higher mortality rate in the CCP database than elderly Whites, at each time frame. Calcium channel blocker therapy was associated with improved survival in both Whites and Blacks, although Blacks continued to have lower survival rates with CCBs when compared with Whites.

Black or African American↗
PubMedDate not supplied

The senior practicum.

Senior practicum offers students valuable time to apply knowledge from the entire nursing program within a supportive setting while having the benefit of direct supervision from an experienced clinician. Benefits to agencies include a well-prepared practitioner who is thoroughly oriented to agency policies and procedures. The authors describe the practicum experience of a baccalaureate nursing program and discuss the benefits from multiple points of view.

Clinical Clerkship↗