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Biomedical subjects

Donna A Williams

Publications and source records attributed to Donna A Williams.

7 recordsLinked to original sources
PubMed2006

Change in shear stress (Deltatau)/hydraulic conductivity (Lp) relationship after pronase treatment of individual capillaries in situ.

A complex glycoprotein meshwork covers the inner wall of blood vessels and is implicated in mechanotransduction of fluid shear stress (tau). A relationship between Deltatau and capillary Lp has been established. The purpose of this study was to evaluate Lp in response to Deltatau after exposing the capillary lumen to a mild, non-specific protease selected to disrupt its inner matrix. We hypothesized that Lp would not correlate with Deltatau after enzyme treatment. Frogs (Rana pipiens, n=69) were pithed and the mesentery was exteriorized. Lp was assessed at 30 cm H2O using the modified Landis technique after an abrupt, square wave Deltatau produced by a physiologically relevant increase in pressure. Perfusate solutions were 10 mg ml-1 BSA/frog Ringer's (Control) or 0.1 mg ml-1 pronase in BSA/Ringer's (1 min) then BSA/Ringer's alone (Test). Mean (+/-SE) control Lp following Deltatau was 2.2+/-0.2 x 10(-7) cm s-1 cm H2O-1 and individual values correlated positively with Deltatau (r=0.85, P<0.0001, n=41). After pronase, mean Test Lp (17.6+/-2.5 x 10(-7) cm s-1 cm H2O-1) was higher compared to control and Deltatau/Lp plots revealed two subsets of capillaries. Lp correlated strongly with Deltatau in capillaries with diameters 15 microm (r=0.96, P=0.0001, n=8). Slopes were 3.9- and 8.7-fold higher, respectively, compared to control. These data suggest a protective role for luminal constituents of intact capillaries. Mechanisms involved in capillary responses to flow-induced, mechanical stimuli may be located in the cellular structures that form capillaries.

Algorithms↗
PubMed2005

Elevated sacral skin temperature (T(s)): a risk factor for pressure ulcer development in hospitalized neurologically impaired Thai patients.

Pressure ulcer incidence and sacral skin temperature (T(s)) were measured in hospitalized neurologically impaired Thai patients ( n = 17) positioned supine and then laterally. Pressure ulcer incidence within 2 weeks of admission was 47%. Regardless of reclining position, mean sacral T(s) in subjects who developed a pressure ulcer was higher ( p < .01) than those who did not develop an ulcer. The data suggest that T(s) may increase at least 1.2 degrees C 24-96 hr before sacral pressure ulcer development. Sacral T(s) may be an objective predictor of sacral pressure ulcer development in hospitalized neurologically impaired Thai patients.

Adult↗
PubMed2005

Impact of pain on outcomes in long-term care residents with and without multiple sclerosis.

OBJECTIVES: To compare long-term care (LTC) residents with and without multiple sclerosis (MS); to compare admission status of pain, physical disability, pressure ulcers, depression, and cognitive performance in LTC residents with and without MS; and to examine the impact of MS and pain on outcomes 90 and 180 days after LTC admission. DESIGN: Retrospective analysis of a large data set. SETTING: LTC facilities in Missouri. PARTICIPANTS: Residents admitted to non-hospital-based LTC facilities. MEASUREMENTS: Minimum Data Set/Resident Assessment Instrument, Version 2.0; Activities of Daily Living Scale; Cognitive Performance Scale. RESULTS: Residents with and without MS had similar pain prevalence and intensity after admission, with daily pain more frequent in residents with MS (P=.03). On admission, residents with MS had more physical disability (P<.001) and a greater prevalence of pressure ulcers (P=.004) and depression (P<.001) than residents without MS. In all LTC residents, initial pain status was associated with physical disability (P<.001), pressure ulcers (P<.001), depression (P<.001), and cognitive performance (P<.001) 90 and 180 days after admission. A diagnosis of MS was associated with physical disability (P<.001) 90 and 180 days after admission and pressure ulcer development 180 days after admission (P=.02). CONCLUSION: Residents with MS were more physically disabled and had more frequent pain and a higher prevalence of pressure ulcers and depression on admission than residents without MS. Pain, or lack thereof, in residents with and without MS on admission may warn of problems that could occur within 6 months after admission to a LTC facility.

Cognition Disorders↗
PubMed2004

Nursing home quality and pressure ulcer prevention and management practices.

OBJECTIVES: To measure pressure ulcer quality indicator (QI) scores and to describe the self-reported skin integrity assessment, pressure ulcer risk assessment, and pressure ulcer prevention and treatment practices in long-term care facilities (LTCFs). DESIGN: Retrospective analysis of a large data set and comparative survey. SETTING: LTCFs in Missouri. PARTICIPANTS: Three hundred sixty-two LTCFs participated in the survey. Three hundred twenty-one facilities had pressure ulcer QI scores between April 1 and September 30, 1999. MEASUREMENTS: Pressure ulcer QI scores, Pressure Ulcer Prevention & Treatment Practices Survey. RESULTS: The mean+/-standard deviation pressure ulcer QI score was 10.9+/-6.2%, with a risk-adjusted score of 15.7+/-8.9% for high-risk residents and 3.1+/-3.6% for low-risk residents. Minimizing head-of-bed elevation to less than 30 degrees was used by fewer than 20% of facilities. More than 40% of facilities used a risk assessment tool that was not evidence based. Fewer than 13% of facilities used the Agency for Health Care Policy and Research pressure ulcer prevention and treatment guidelines. No relationship was found between the number of prevention strategies (P=.892) or the number of treatment strategies (P=.921) and the pressure ulcer QI scores. CONCLUSION: Valid and reliable pressure ulcer risk assessment tools are seriously underused. Evidence-based pressure ulcer prevention and treatment guidelines appear to be rarely implemented. This study provides a basis for developing educational and quality improvement programs and future research related to pressure ulcer prevention and treatment in LTCFs.

Aged↗
PubMed2003

Intact capillaries sensitive to rate, magnitude, and pattern of shear stress stimuli as assessed by hydraulic conductivity (Lp).

Magnitude of abrupt changes in fluid shear stress (Delta tau) correlates with capillary hydraulic conductivity (Lp). Cultured endothelial cells differentiate between rate of change in and pattern of fluid stimulation; however, neither rate nor pattern sensitivity has been evaluated in individual capillaries. We hypothesized that Lp would be greater following abrupt compared to slow Delta tau and that magnitude of Delta tau would correlate with Lp regardless of rate. Mesenteric venular capillaries (VC, n=41) located in pithed North American leopard frogs (Rana pipiens) were cannulated either above or at in situ pressure to induce abrupt (<0.1 s) or slow (1-5 min) Delta tau. Lp was assessed always at the same pressure (30 cm H2O) using the modified Landis technique. Mean +/- SE Lp was sixfold higher (P=0.005) following abrupt (19.0 +/- 3.9 x 10(-7)) compared to slow (2.7 +/- 0.9 x 10(-7) cm/s/cm H2O) Delta tau after accounting for stimulus pattern variability. Linear relationships between Lp and Delta tau existed for both abrupt [Lp = 0.026(Delta tau)-1.6, R2=0.90, P=0.0001] and slow [Lp = 0.005(Delta tau)-0.3, R2=0.82, P=0.03] stimuli. These results suggest that frog mesenteric VC sense unique characteristics of Delta tau and respond by altering Lp.

Animals↗
PubMed2003

Species characterization of plasma nitrite/nitrate (NOx) concentration.

Experiments were designed to detect and determine differences between nitrite/nitrate concentration ([NOx]) in plasma across 15 species selected from seven classes of vertebrates. Blood collected in syringes was placed immediately into ethylenediaminetetraacetic acid (EDTA)-containing tubes and was centrifuged. Plasma [NOx] was determined by measurement of chemiluminescence. Across classes of vertebrates, baseline plasma [NOx] ranged from 0.6 to 171.3 nmol/ml. Mean +/- SD plasma [NOx] was highest in a fresh-water, jawless fish (lamprey, 95.5 +/- 9.1 nmol/ml) and lowest in a saltwater cartilaginous fish (skates, 1.1 +/- 0.4 nmol/ml). Both amphibians tested had a wide range in plasma [NOx], which was explained partly by temporal changes during the year. Within the mammalian class, plasma [NOx] ranged from 3.8 to 43.2 nmol/ml. Results of this study indicate that NO is detectable in plasma of all classes of vertebrates and that baseline concentration varies among species.

Animals↗