Biomedical subjects

S M Williams

Publications and source records attributed to S M Williams.

At least 55 records · Page 3Linked to original sources

PubMed2001

X-ray study of oil-microemulsion and oil-water interfaces in ternary amphiphilic systems.

We present x-ray reflectivity and diffuse scattering measurements from the interfaces between oil-rich and microemulsion bulk phases and between oil-rich and water-rich phases in three-component microemulsion systems (consisting of water, alkane, and C(i)E(j), where the last represents n-alkyl polyglycol ether with i=4,6,10 and j=1,2,4). The x-ray measurements are analyzed with a two-parameter fit that determines the interfacial roughness, varying from 25 A to 160 A, and the interfacial tension, varying from 1.4 mN/m to 0.03 mN/m, for these samples. Although a nonmonotonic profile at the oil-microemulsion interface is not observed, these measurements exclude the presence of oscillating profiles with repeat distances greater then 500 A.

Journal Article↗

PubMed2001

A longitudinal study of health related quality of life and utility measures in patients with advanced breast cancer.

Health related quality of life (HRQOL) measures are now accepted as indicators of efficacy in the palliative treatment of cancer. Utility measures may also provide valuable information yet they have been applied less frequently. To assess the application of a time trade-off (TTO) utility measure and its concordance with the Spitzer uniscale and quality of life index (QLI) 38 women with advanced, symptomatic breast cancer were studied over a 12 month period. The correlation coefficient for QLI and TTO values was 0.54 and for uniscale and TTO 0.62. Using generalized estimating equations the regression of TTO scores on QLI and uniscale scores was significant at baseline. In longitudinal analyses results were significant only for QLI. Although all participants completed the HRQOL measures only 24 (63%) were prepared to trade time. The remaining 14 (32%) stated they felt too well to trade. Those prepared to trade time recorded significantly worse mean HRQOL scores throughout the study compared to those who felt too well to trade and had tumors which showed a poorer response to therapy. In this preliminary study utility and HRQOL scores were generally favorable throughout the 12 month study period and showed fair to moderate concordance. Further research in larger patient groups is required to better define the relationships between utility and HRQOL measures.

Adult↗

PubMed2001

The effect of meals rich in thermally stressed olive and safflower oils on postprandial serum paraoxonase activity in patients with diabetes.

OBJECTIVE: To determine the effects of meals rich in thermally stressed safflower (TSAF) and olive (TSOL) oils on postprandial serum paraoxonase (PON1) arylesterase activity and low density lipoprotein (LDL) oxidation in patients with type 2 diabetes. DESIGN: A randomised cross-over study. SETTING: Diabetes clinic and general practice. SUBJECTS: Fourteen patients (six men and eight women) with type 2 diabetes, aged 48-67 y, glycated haemoglobin <10% and fasting blood glucose <11 mmol/l were recruited. INTERVENTIONS: Patients received a milkshake rich in TSAF or TSOL and at least a week later they received the alternate milkshake. These fats contained high levels of lipid oxidation and degradation products. Blood samples were taken fasted and 4 h after consumption of the milkshake. MAIN OUTCOME MEASURES: Serum PON1 activity and lag time in LDL oxidation. RESULTS: After the meal rich in TSOL, serum PON1 activity increased significantly in women (12 (2.22) micromol/ml/min, mean (95% confidence interval), P=0.03) and not in men (0 (-4.4) micromol/ml/min) during the postprandial period. The increase in PON1 activity after the TSOL meal was significantly (P=0.03) greater in women compared with men. In women, the increase in serum PON1 activity after the TSOL meal was significantly different (13 (1.25) micromol/ml/min, P=0.04) compared with the corresponding change (-1 micromol/ml/min) after the TSAF meal. The lag time in LDL oxidation and indices of oxidative stress and antioxidant capacity did not vary significantly during the meals. CONCLUSIONS: Meals rich in TSOL may increase postprandial serum PON1 activity in middle-aged and older diabetic women. This change is potentially anti-atherogenic and may favour the use of olive oil over polyunsaturated fats in the diet of patients with type 2 diabetes. SPONSORSHIP: The study was supported by a grant from the National Heart Foundation of New Zealand.

Aged↗

PubMed2001

Hormone-replacement therapy increases serum paraoxonase arylesterase activity in diabetic postmenopausal women.

The paraoxonase (PON1) enzyme is associated with high-density lipoproteins (HDL) in the blood and is low in patients with type 2 diabetes. Hormone-replacement therapy (HRT) can increase HDL cholesterol levels, but its effect on serum PON1 arylesterase activity is uncertain. The aim of the present study was to determine the effect of 6 months' HRT with conjugated equine estrogen and medroxyprogesterone acetate on serum PON1 arylesterase activity in postmenopausal women with type 2 diabetes. Serum PON1 activity was measured immediately before and at the end of the second arm of a randomized, placebo-controlled, crossover with washout study originally designed to test the effect of HRT on plasma lipids in diabetic postmenopausal women. Baseline serum PON1 arylesterase activity was significantly (P <.001) lower in the postmenopausal diabetic women (149 +/- 38 micromol/mL/min; n = 47) than values in healthy postmenopausal women (173 +/- 32 micromol/mL/min; n = 51). Serum PON1 activity increased (10%) significantly (P =.009) in diabetic women treated with HRT compared with placebo. A significant (P =.02) interaction between baseline PON1 activity and treatment indicated a greater increase in PON1 activity during HRT in women with lower baseline activities. At baseline, serum PON1 arylesterase activity was correlated significantly with plasma HDL cholesterol levels in diabetic women (r = 0.333, P =.01, n = 47), and the increase in serum PON1 activity was correlated significantly with the change in plasma HDL cholesterol during HRT (r = 0.659, P =.0001, n = 28). These data suggest that serum PON1 activity is abnormally low in postmenopausal women with type 2 diabetes and increases during HRT, particularly in women with lower baseline levels and in those who show a concomitant increase in HDL cholesterol.

Aged↗

PubMed2001

Bone mineral density and body composition in boys with distal forearm fractures: a dual-energy x-ray absorptiometry study.

OBJECTIVE: To determine whether boys with distal forearm fractures differ from fracture-free control subjects in bone mineral density (BMD) or body composition. STUDY DESIGN: A case-control study of 100 patients with fractures (aged 3 to 19 years) and l00 age-matched fracture-free control subjects was conducted. Weight, height, and body mass index were measured anthropometrically. BMD values and body composition were determined by dual-energy x-ray absorptiometry. RESULTS: More patients than control subjects (36 vs l4) were overweight (body mass index >85th percentile for age, P <.001). Patients had lower areal (aBMD) and volumetric (BMAD) bone mineral density values and lower bone mineral content but more fat and less lean tissue than fracture-free control subjects. The ratios (95% CIs) for all case patients/control subjects in age and weight-adjusted data were ultradistal radius aBMD 0.94 (0.91-0.97); 33% radius aBMD 0.96 (0.93-0.98) and BMAD 0.95 (0.91-0.99); spinal L2-4 BMD 0.92 (0.89-0.95) and BMAD 0.92 (0.89-0.94); femoral neck aBMD 0.95 (0.92-0.98) and BMAD 0.95 (0.91-0.98); total body aBMD 0.97 (0.96-0.99), fat mass 1.14 (1.04-1.24), lean mass 0.96 (0.93-0.99), and total body bone mineral content 0.94 (0.91-0.97). CONCLUSIONS: Our results support the view that low BMC, aBMD, and BMAD values and high adiposity are associated with increased risk of distal forearm fracture in boys. This is a concern, given the increasing levels of obesity in children today.

Absorptiometry, Photon↗

PubMed2001

Can dietary treatment of non-anemic iron deficiency improve iron status?

OBJECTIVE: To investigate the efficacy of, first, a dietary regimen involving increased consumption of iron-rich foods and enhancers of iron absorption and decreased consumption of inhibitors of iron absorption and, second, a low dose iron chelate iron supplement, for increasing iron stores in young adult New Zealand women with mild iron deficiency (MID). METHODS: The study was a 16 week randomized placebo-controlled intervention. Seventy-five women aged 18 to 40 years with MID (serum ferritin < 20 microg/L and hemoglobin > or = 120 g/L) were assigned to one of three groups: Placebo, Supplement (50 mg iron/day as amino acid chelate) or Diet. Participants in the Diet Group were given individual dietary counseling to increase the intake and bioavailability of dietary iron. Dietary changes were monitored by a previously validated computer-administered iron food frequency questionnaire. RESULTS: Diet Group members significantly increased their intake of flesh foods, heme iron, vitamin C and foods cooked using cast-iron cookware and significantly decreased their phytate and calcium intakes. Serum ferritin increased in the Supplement and Diet Groups by 59% (p=0.001) and 26% (p=0.068), respectively, in comparison to the Placebo Group. The serum transferrin receptor:serum ferritin ratio decreased by 51% in the Supplement Group (p=0.001), and there was a non-significant decrease of 22% (p=0.1232) in the Diet Group. CONCLUSIONS: This study is the first, to our knowledge, to demonstrate that an intensive dietary program has the potential to improve the iron status of women with iron deficiency.

Adolescent↗

PubMed2001

Diagnosing insulin resistance in the general population.

OBJECTIVE: Difficulties in measuring insulin sensitivity prevent the identification of insulin-resistant individuals in the general population. Therefore, we compared fasting insulin, homeostasis model assessment (HOMA), insulin-to-glucose ratio, Bennett index, and a score based on weighted combinations of fasting insulin, BMI, and fasting triglycerides with the euglycemic insulin clamp to determine the most appropriate method for assessing insulin resistance in the general population. RESEARCH DESIGN AND METHODS: Family history of diabetes, BMI, blood pressure, waist and hip circumference, fasting lipids, glucose, insulin, liver enzymes, and insulin sensitivity index (ISI) using the euglycemic insulin clamp were obtained for 178 normoglycemic individuals aged 25-68 years. Product-moment correlations were used to examine the association between ISI and various surrogate measurements of insulin sensitivity. Regression models were used to devise weights for each variable and to identify cutoff points for individual components of the score. A bootstrap procedure was used to identify the most useful predictors of ISI. RESULTS: Correlation coefficients between ISI and fasting insulin, HOMA, insulin-to-glucose ratio, and the Bennett index were similar in magnitude. The variables that best predicted insulin sensitivity were fasting insulin and fasting triglycerides. The use of a score based on Mffm/I = exp[2.63 - 0.28ln(insulin) - 0.31ln(TAG)] rather than the use of fasting insulin alone resulted in a higher sensitivity and a maintained specificity when predicting insulin sensitivity. CONCLUSIONS: A weighted combination of two routine laboratory measurements, i.e., fasting insulin and triglycerides, provides a simple means of screening for insulin resistance in the general population.

Adult↗

PubMed2001

Determinants of overweight and obesity in patients with bipolar disorder.

OBJECTIVE: To examine lifestyle-related determinants of the excess adiposity observed in patients with bipolar disorder. METHOD: Eighty-nine male and female patients with DSM-IV bipolar disorder who were attending a specialist bipolar clinic or another psychiatric outpatient clinic (19% with body mass index [BMI] > or = 30) and 445 age- and sex-matched reference subjects (12% with BMI > or = 30) participated in a cross-sectional study of nutrient intake and physical activity. Main outcome measures included macronutrient intakes (assessed with 24-hour recall), percentage of energy derived from various food sources, and physical activity levels (assessed with the Life in New Zealand Questionnaire). RESULTS: Mean total energy intake was higher in female patients than in reference subjects: 8468 kJ compared with 6980 kJ (95% confidence interval [CI] = 583 to 2392 kJ). Total daily sucrose and percentage of energy from carbohydrate were higher in patients than in reference subjects; for women, 73 g and 49% (95% CI = 20 to 56 g, 3% to 10) and for men, 89 g and 47% (95% CI = 15 to 59 g, 3% to 9%). Total fluid intake and intake of sweetened drinks were higher in patients than in reference subjects (ratio of geometric means: women, 1.2 and 2.3, respectively [95% CI = 1.1 to 1.4, 1.9 to 2.8]; men, 1.1 and 2.1, respectively [95% CI = 1.0 to 1.23, 1.8 to 2.41). Patients reported fewer episodes of low- to moderate-intensity and high-intensity physical activity as compared with reference subjects (p < or = .05). CONCLUSION: This study confirms that drug-induced changes in food preference can lead to an excessive energy intake largely as a result of a high intake of sucrose. Dietary advice regarding the use of energy-rich beverages along with encouragement to increase levels of physical activity may help prevent weight gain in bipolar patients. The findings also have some bearing on dietary advice aimed at avoiding overweight and obesity in the general population.

Adult↗

PubMed2001

Ventilatory responses to rebreathing in infants exposed to maternal smoking.

UNLABELLED: This study assessed the effect of maternal smoking during pregnancy on ventilatory and waking responses of infants to a respiratory challenge. This challenge mimicked the time-course and concentration of gases that an infant would experience rebreathing face-down into soft bedding. Control (C; n = 97) and smokers' infants (SM; n = 96) were studied at ages I and 3 mo. Asphyxial gas (hypercapnia/hypoxia) was delivered to the supine sleeping baby via a hood by slowly altering the inspired air: CO2 maximum 5% and O2 minimum 13.5%. Respiratory pattern was recorded by inductive plethysmography as the sum of ribcage and abdominal movements. The change in ventilation with inspired CO2 was measured over 5-6 min of the test. The slope of a linear curve fit relating inspired CO2 to the logarithm of ventilation was taken as a quantitative measure of ventilatory asphyxial sensitivity (VAS). Protective responses were graded from 1: no waking and an estimated arterial carbon dioxide tension (PaCO2) > or = 60 mmHg (least protective), to 4: fully awake (most protective). The results showed VAS was higher in SM infants than controls: +0.03 (p = 0.04). The oxygen saturation (SaO2) of SM infants fell -0.4% (p = 0.02) more than SaO2 of controls despite a greater tidal volume increase: +13.0% (p = 0.04). Overall protective responses were the same between groups, but grade 1, although rare, was found in 7 SM infants and only 4 control infants; this difference was not significant. CONCLUSION: The study did not confirm the postulate that infants of mothers who smoked during pregnancy have a reduced ventilatory response or raised waking thresholds.

Female↗

PubMed2000

Conserved worldwide linkage disequilibrium in the human factor XI gene.

We have identified, in four diverse human populations, five common single-nucleotide polymorphisms (SNPs) in the coding region of the gene for the blood coagulation protease factor XI. Each SNP has an allele frequency >5% in at least one population. Three of the SNPs (C472T, A844G, and T1234C), spread out over approximately 10 kb of genomic DNA, are in marked linkage disequilibrium (LD) with one another (P < 10(-4)). Interestingly, haplotypes associated with the linked SNPs are conserved across all populations studied, despite significantly different allele frequencies between populations. The presence of such common, widely dispersed haplotypes could complicate the interpretation of LD studies and emphasizes the need for a better understanding of general patterns of LD to facilitate identification of genes for common disorders.

Factor XI↗

PubMed2000

The relevance of visual perception to cortical evolution and development.

The quality of brightness--perhaps the simplest visual attribute we perceive--appears to be determined probabilistically. In this empirical conception of the perception of light, the stimulus-induced activity of visual cortical neurons does not encode the retinal image or the properties of the stimulus per se, but associations (percepts) determined by the relative probabilities of the possible sources of the stimulus. If this theory is correct, the rationale for the prolonged postnatal construction of visual circuitry--and the evolution of this visual scheme--is to strengthen and/or create by activity-dependent feedback the empirically determined association on which vision depends.

Animals↗

PubMed2000

Impact of childhood cancer on the mental health of parents.

BACKGROUND: When a child is diagnosed with cancer, the family experiences great stress and disruption to daily life. As part of a national study in New Zealand, we evaluated the mental health of mothers and fathers of children with cancer, making comparisons to parents of children from the general population. PROCEDURE: This was a cross-sectional study. All children diagnosed with cancer at ages 0-14 years in New Zealand during a defined period were ascertained from the national cancer registry and other databases. The population-based comparison children were selected using national birth records. Parents from both groups completed self-administered questionnaires containing the General Health Questionnaire (GHQ-12) and other measures. The analyses included 218 mothers and 179 fathers of children with cancer, and 266 mothers and 224 fathers of children in the comparison group. Multivariate regression was used to adjust for demographic and socioeconomic characteristics, life events, and social support. RESULTS: Mothers and fathers of children with cancer had poorer GHQ-12 and mood rating scores than those of controls. The adjusted difference in the mean total GHQ-12 score (comparing mothers of children with cancer to mothers of controls) was 2.2 (95% confidence interval 1.3-3.2). The 12 items of the GHQ were each scored 0-3, and the total score was the sum, so 2 points is a small difference. For fathers the difference was 1.5 (95% confidence interval 0.6-2.4). Some subgroups of cancer group parents had poorer emotional health scores than others, including those with poor social support and no paid employment and also those who were bereaved. CONCLUSIONS: We found statistically significant but small differences between the mental health of parents of children with cancer and controls. The small differences suggest that as a group the parents of children with cancer are relatively resilient.

Adaptation, Psychological↗

PubMed2000

Reviews of evidence regarding interventions to improve vaccination coverage in children, adolescents, and adults. The Task Force on Community Preventive Services.

This paper presents the results of systematic reviews of the effectiveness, applicability, other effects, economic impact, and barriers to use of selected population-based interventions intended to improve vaccination coverage. The related systematic reviews are linked by a common conceptual approach. These reviews form the basis for recommendations by the Task Force on Community Preventive Services (the Task Force) regarding the use of these selected interventions. The Task Force recommendations are presented on pp. 92-96 of this issue.

Adolescent↗

PubMed2000

Further testing of the xerostomia inventory.

OBJECTIVE: To examine the concurrent validity and temporal stability of the xerostomia inventory (XI), an 11-item summated rating scale that was developed to enable measurement of the severity of dry mouth symptoms in epidemiologic and clinical studies. STUDY DESIGN: A prospective cohort study design was used. Measurements of the severity of dry-mouth symptoms were made with the use of the XI and a standard dry-mouth question ("How often does your mouth feel dry?") on 2 groups of people at baseline, 2, 4, and 6 months. The 2 groups were chosen for their differing symptom trajectories: the onset group (N = 57) comprised patients who were about to undergo radiotherapy for head and neck cancer; and the normal group (N = 55) was a convenience sample of middle-aged and older individuals who were not expected to undergo changes in mouth dryness over the study period. RESULTS: The sex distributions of the 2 groups were similar, but the onset group was younger than the normal group overall. Baseline XI scores were higher among the onset group. The mean XI scores of the normal group did not differ over the observation period, indicating acceptable temporal stability of the XI. The scores of the onset group showed a substantial increase between baseline and 2 months, after which the 2-month level was sustained over the remainder of the study period. That these patterns were mirrored in the percentage responding "frequently" or "always" to the standard question provided further evidence for the concurrent validity of the XI. Linear regression was used to estimate the difference between the final scores after adjusting for age, sex, and initial difference in scores between the 2 groups. This was found to be 9.17 (95% CI 6.24, 12.10) and confirmed that undergoing radiotherapy for head/neck cancer was associated with a substantial increase in the severity of xerostomia symptoms. CONCLUSION: The xerostomia inventory appears to be a valid multi-item method for measuring the severity of the symptoms of dry mouth in clinical and epidemiologic studies.

Adult↗

PubMed2000

Temporal patterns of injury during a rugby season.

The aim of this study was to describe temporal patterns in the frequency, nature and circumstances of injuries occurring among a cohort of 356 rugby players during a club rugby season in New Zealand. It was found that the rate of injury in games decreased significantly over time in both males and females. The reduction in injury rate over the season was more pronounced in some grades, but no differences were found when examined by gender. playing position, age, ethnicity or by health and fitness types. Trends in injury rate were consistent over the rugby season and did not appear to be the result of a bias involving under-reporting of end-of-season injuries. The types and severity of injury remained relatively constant, but the proportion of injuries occurring in back play fell significantly over the season and injuries were more likely to occur in the trunk body region as the season progressed. This study supported the hypothesis that higher rates of injury occur at the start of the rugby season and decrease over the course of the season. This reduction is consistent over time and across player types, and is not attributable either to decreasing injury severity or to increasing player fitness.

Athletic Injuries↗

PubMed2000

Overweight and obese children have low bone mass and area for their weight.

OBJECTIVES: To determine whether girls and boys categorized from body mass index (BMI) values as overweight or obese for their age have lower bone mineral content (BMC) or lower bone area in relation to total body weight than children of normal adiposity. DESIGN: Cross-sectional study in a university bone research unit. SUBJECTS: Two hundred girls and 136 boys aged 3-19 y recruited from the general population by advertisement. MEASUREMENTS: Total body BMC (g) and bone area (cm2) measured by dual energy X-ray absorptiometry (DXA) in relation to body weight (kg), lean tissue mass (kg) and fat mass (kg) in boys and girls of three different BMI percentile groupings: normal weight (BMI<85th percentile); overweight (85 to 94th BMI percentile); obese (> or =95th BMI percentile). RESULTS: Obese children had higher BMC, bone area, and fat mass for chronological age than those of normal body weight (P<0.001). In spite of this the observed values for age-adjusted total body BMC and bone area relative to body weight were each lower than predicted values, in both overweight and obese children (2.5-10.1% less, P<0.05) than in children of lower adiposity. CONCLUSION: In overweight and obese boys and girls there is a mismatch between body weight and bone development during growth: their bone mass and bone area are low for their body weight.

Adipose Tissue↗

PubMed2000

The inactivation of foot and mouth disease, Aujeszky's disease and classical swine fever viruses in pig slurry.

The aim of the study was to investigate the decontamination of pig slurry containing exotic viruses of pigs, foot AND mouth disease virus (FMDV), Aujeszky's disease virus (ADV) AND classical swine fever virus (CSFV). Laboratory-scale decontamination experiments showed that FMDV, ADV and CSFV were heat inactivated in slurry within 3 min at 67 degrees C, 3 min at 62 degrees C and 3 min at 60 degrees C and in Glasgow Eagles medium within 5 min at 67 degrees C, 4 min at 65 degrees C and 2 min at 65 degrees C, respectively. At pilot scale, FMDV was heat inactivated at 66 degrees C in water and 61 degrees C in slurry, ADV at 61 degrees C in water or slurry and CSFV at 62 degrees C in water and 50 degrees C in slurry. Treatment of pig slurry for the inactivation of exotic viruses may be achieved through the use of a thermal pilot plant operating in continuous mode. The work demonstrates the suitability of thermal treatment in ensuring the safety of pig slurry following a disease outbreak.

Animals↗

PubMed2000

Radiological review of accident and emergency radiographs: a 1-year audit.

AIM: To assess the impact and cost effectiveness of a system of radiological review of accident and emergency (A&E) plain films. MATERIALS AND METHODS: Review documentation was studied retrospectively over a 1-year period. Six hundred and eighty-four actual or suspected errors in the initial radiological interpretation by A&E staff were highlighted by radiologists in training. These selected 'red reports' were then further reviewed by a musculoskeletal radiologist and a more senior member of the A&E team. RESULTS: Three hundred and fifty-one missed or strongly suspected fractures were detected, with ankle, finger and elbow lesions predominating. Other errors included 11 missed chest radiograph abnormalities and 24 A&E false-positives. Radiologists in training tended to over-report abnormalities with an 18% false-positive rate when compared to the subsequent musculoskeletal radiology opinion. Following review, further action was taken by A&E staff in 286 (42.6%) of cases. No operative intervention was required in those patients with a delayed or missed A&E diagnosis. Consideration is given to the cost of providing this form of review and the impact of medico-legal factors. CONCLUSION: Compared with the large numbers of patients seen and radiographed in a busy A&E department, the number of radiological errors was small. There were even fewer changes in management. Despite this, concern over litigation, clinical governance and future work patterns in A&E make this form of review a useful means of risk reduction in a teaching hospital.Williams, S. M. (2000). Clinical Radiology55, 861-865

Cost-Benefit Analysis↗