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Biomedical subjects

D Wilson

Publications and source records attributed to D Wilson.

At least 127 records · Page 7Linked to original sources
PubMed2000

Serum levels of vascular endothelial growth factor in preeclamptic and normotensive pregnancy.

The purpose of these studies was first to determine if vascular endothelial growth factor (VEGF), a vascular permeability agent, is increased in the serum of women with preclinical and clinical preclampsia (PE), and second to determine how these levels change after delivery. Twenty preeclamptic and 25 normotensive women at term consented to have blood taken pre- and post-delivery. Ten preeclamptic, 10 gestational hypertensive, and 28 normotensive women had blood collected respectively at 12, 20, and 30 weeks gestation and predelivery. Serum was extracted from all samples, and VEGF concentrations were determined by radioimmunoassay. Predelivery, the median serum VEGF concentration in the preeclamptic group was 51.7 ng/mL, and in the control group the concentration was 13.9 ng/mL (P<0.0001). Serum VEGF concentrations fell within 24 hours of delivery in both groups, which resulted in median values of 3.8 ng/mL and 3.2 ng/mL respectively (P<0.3). At 12 and 20 weeks, there was no significant difference between the serum VEGF concentrations in the 3 groups (P<0.3, 0.052 respectively). At 30 weeks, prior to the onset of clinical PE, the serum VEGF levels in the eventual preeclamptic group were elevated significantly compared with the gestational hypertensive and normotensive groups (P<0.001). Predelivery serum VEGF concentrations were significantly elevated in the preeclamptic group and were similar to those in the first study (P<0.0001). These findings suggest that VEGF may be important in the pathophysiology of PE and has the potential to act as a preclinical marker for the condition.

Adult↗
PubMed2000

Dual phase hepatic CT: influence of scanning direction on liver attenuation.

OBJECTIVE: We measured changes in hepatic attenuation during arterial and portal phase acquisition of hepatic CT in the craniocaudal and caudocranial directions. SUBJECTS AND METHODS: In 10 of 20 patients undergoing dual phase helical CT during staging for colorectal cancer, images in both phases were obtained in the craniocaudal direction. Ten patients underwent imaging in the caudocranial direction. Attenuation values in the aorta and in the peripheral and central liver regions of interest were measured on each slice. Central and peripheral liver attenuation was also measured in 10 additional patients undergoing unenhanced CT. RESULTS: Both peripheral and central regions of interest revealed progressively increasing attenuation during the arterial phase, irrespective of scanning direction. During the portal phase, hepatic attenuation was stable in the craniocaudal direction but decreased in the caudocranial direction (p < 0.05, Wilcoxon's signed rank sum test). Central hepatic attenuation was lower than peripheral attenuation in unenhanced livers and in enhanced livers during both phases of caudocranial acquisition. We determined no significant difference during the arterial phase of enhancement in the craniocaudal direction. CONCLUSION: The direction of acquisition does not influence sequential liver enhancement during the arterial phase. Craniocaudal acquisition produces more stable enhancement during the portal phase. Differences in attenuation between the central and peripheral areas of the liver are probably unrelated to contrast administration.

Adult↗
PubMed1999

A South Australian population survey of the ownership of asthma action plans.

OBJECTIVE: To examine the relationships between ownership of written asthma action plans, asthma morbidity, use of devices, and patients' perceptions of their asthma management. DESIGN AND SETTING: A random population survey (in 1996) of the South Australian population aged 15 years or over, using interviewers to administer a questionnaire. PARTICIPANTS: People who reported that they had current, doctor-diagnosed asthma. MAIN OUTCOME MEASURES: Prevalence of written asthma action plans; night-time awakenings from asthma; ownership of peak flow meters; and people's perceptions of their asthma management. RESULTS: The ownership of asthma action plans by people with self-reported asthma was 33% and has declined since 1995 (42%; P < 0.001). Fifteen per cent were awakened weekly or more frequently by asthma symptoms. These people were more likely to have a peak flow meter and a written action plan, but less likely to consider they had been provided with enough information about their asthma, to feel comfortable managing their asthma, or to find it easy to see their doctor. Having a written asthma action plan was associated with regular corticosteroid use, understanding asthma, having enough information and owning a peak flow meter. CONCLUSIONS: Ownership of asthma action plans in South Australia is suboptimal. Before we develop new strategies to improve asthma outcomes, we must determine whether there is a need to target people with less severe asthma and/or improve the use of guidelines by health professionals.

Asthma↗
PubMed1999

Renal function following combination chemotherapy with ifosfamide and cisplatin in patients with osteogenic sarcoma.

BACKGROUND: Ifosfamide and cisplatin are active agents that are currently used in the treatment of osteosarcoma. Nephrotoxicity has been reported following their use in combination and alone. This study evaluates renal function in children and adolescents (median age 16 years) at least 3 months following completion of a chemotherapy regimen which included 54 g/m2 ifosfamide, 360 mg/m2 cisplatin, doxorubicin, and high-dose methotrexate. PROCEDURE: Mean glomerular filtration rate (GFR) was determined by inulin or iothalamate clearance; proximal tubular function was evaluated by measuring fractional excretion of glucose (FEglu), tubular maximum phosphate reabsorption per GFR (TMP/GFR), FE of urate, and 24-hour amino acid excretion. Distal tubular function was evaluated by 24-hour urinary calcium, FE of magnesium, and urinary osmolality after water deprivation. Twenty-four-hour urinary protein excretion was measured. RESULTS: The mean GFR was 97 ml/min/1.73 m2. Although 10 of 24 patients had GFRs lower than normal, the lowest value was only 22% below the lower limit of normal and would not account for any clinical compromise. Proximal tubular function evaluation revealed normal FEglu, normal mean TMP/GFR values, and high FE of urate (1 5.7%). Two of twenty-four patients were shown to have mild generalized aminoaciduria. Distal tubular function evaluation showed normal 24-hour urinary calcium levels (mean 3.4 mg/kg) and FE of magnesium as well as normal urinary osmolality. Twenty-four-hour urinary protein excretion was normal in all patients. CONCLUSIONS: The lack of clinically significant renal abnormalities observed in patients who received combination chemotherapy with ifosfamide and cisplatin for osteosarcoma is encouraging for future osteosarcoma protocol development.

Adolescent↗
PubMed1999

The health-related quality-of-life of never smokers, ex-smokers, and light, moderate, and heavy smokers.

BACKGROUND: Health related quality-of-life is recognized as an important health outcome measure; how ever, it may also have a significant application in smoking reduction and cessation programs. METHODS: Representative population data (n = 3010) was used to compare the quality-of-life status of differ ent smoking categories with never smokers. RESULTS: Statistically significant differences in mean quality-of-life scores, as measured by the SF-36 health status questionnaire, were observed between never smokers, as the reference group, ex-smokers, all smokers, and light, moderate, and heavy smokers. Heavy smokers also scored significantly lower than both other groups of smokers, scoring as low as the 29th percentile of the population on the general health dimension and lower than the 36th percentile of the population on all the mental health dimensions. CONCLUSIONS: The design of public health smoking cessation programs should consider the varying characteristics of different segments of the smoking population. The advantages of improved quality-of-life may strengthen the argument for encouraging heavier smokers to become light smokers as a precursor to total cessation.

Adolescent↗
PubMed1999

Preoperative dextrose does not affect spinal-induced hypotension in elective Cesarean section.

PURPOSE: To determine if preoperative intravenous dextrose affects the incidence and ease of treatment of spinal-induced hypotension in parturients having elective Cesarean section under spinal anesthesia. METHODS: In this prospective, double-blind study, following informed consent, 119 ASA I, II parturients for elective Cesarean section were randomized to receive intravenously either dextrose 5% in normal saline (Group D) or normal saline (Group NS) at 125 ml x hr(-1) for two hours prior to delivery. Following a bolus of 15 ml x kg(-1) normal saline iv, spinal anesthesia was induced with hyperbaric bupivacaine 0.75%, fentanyl and morphine. Hypotension (systolic blood pressure <100 mm Hg or >20% decrease) was treated with fluids and/or vasopressor. DATA COLLECTED: demographics, blood glucose concentrations (fasting, time of spinal, delivery), blood pressure (baseline, one minute intervals from spinal to delivery), neonatal Apgar scores, umbilical blood gas analyses, glucose and lactate concentrations. RESULTS: There was no difference between the two groups in the rate of hypotension (P = 0.272). All parturients who experienced hypotension received fluids, and there was also no difference between the groups in vasopressor requirement [mean dose of ephedrine: Group D = 21.6 mg (95% CI 15.1-28.2), Group NS = 16 mg (95% CI 12.0-20.5)]. CONCLUSION: The routine administration of dextrose 5% at a rate of 5.22 g x hr(-1) preoperatively does not affect the hypotension rate, or make it easier to treat.

Adult↗
PubMed1999

Interaction Between Scientists and Nonscientists in Community-Based Watershed Management: Emergence of the Concept of Stream Naturalization.

/ Watershed management, although dependent on science and engineering, is first and foremost a social process. Given the current emphasis on community-based approaches to environmental decision making, scientists must, more than ever before, understand, appreciate, respect, and immerse themselves within local social contexts. Only by doing so will they be able to ensure that their opinions and information are fairly and meaningfully considered by nonscientists.The authors' personal experience in watershed planning and decision making in the agricultural Midwest is described to illustrate how: (1) formalization of the process of community-based management is not sufficient to guarantee that local people will meaningfully consider scientific information and opinion when making decisions about watersheds, and (2) genuine social interaction between scientists and nonscientists requires a considerable investment of time and energy on the part of the scientist to develop personal relationships with nonscientists based on trust and mutual exchange of information. This experience provides the basis for developing a general conceptual model of the interaction between scientists and nonscientists in community-based watershed management in the agricultural Midwest.An important aspect of integrating science effectively into community-based decision making is the need to revise existing concepts to accommodate place-based contexts. Stream naturalization is introduced as an alternative to stream restoration and rehabilitation, which are viewed as inappropriate management strategies in human-dominated environments. Stream naturalization seeks to establish sustainable, morphologically and hydraulically varied, yet dynamically stable fluvial systems that are capable of supporting healthy, biologically diverse aquatic ecosystems. This general goal is consistent with the types of stream-management practices emerging from community-based decision making in human-dominated, agricultural landscapes. Further research on the linkages between geomorphological and ecological dynamics of human-modified agricultural streams over multiple spatial and temporal scales is needed to provide a sound scientific framework for stream naturalization.KEY WORDS: Community-based decision making; Watershed management; Stream naturalizationhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n3p297.html

Journal Article↗
PubMed1999

Elasticity of the red cell membrane and its relation to hemolytic disorders: an optical tweezers study.

We have used optical tweezers to study the elasticity of red cell membranes; force was applied to a bead attached to a permeabilized spherical ghost and the force-extension relation was obtained from the response of a second bead bound at a diametrically opposite position. Interruption of the skeletal network by dissociation of spectrin tetramers or extraction of the actin junctions engendered a fourfold reduction in stiffness at low applied force, but only a twofold change at larger extensions. Proteolytic scission of the ankyrin, which links the membrane skeleton to the integral membrane protein, band 3, induced a similar effect. The modified, unlike the native membranes, showed plastic relaxation under a prolonged stretch. Flaccid giant liposomes showed no measurable elasticity. Our observations indicate that the elastic character is at least as much a consequence of the attachment of spectrin as of a continuous membrane-bound network, and they offer a rationale for formation of elliptocytes in genetic conditions associated with membrane-skeletal perturbations. The theory of Parker and Winlove for elastic deformation of axisymmetric shells (accompanying paper) allows us to determine the function BH(2) for the spherical saponin-permeabilized ghost membranes (where B is the bending modulus and H the shear modulus); taking the literature value of 2 x 10(-19) Nm for B, H then emerges as 2 x 10(-6) Nm(-1). This is an order of magnitude higher than the value reported for intact cells from micropipette aspiration. Reasons for the difference are discussed.

Biophysical Phenomena↗