Biomedical subjects

S M Williams

Publications and source records attributed to S M Williams.

At least 91 records · Page 5Linked to original sources

PubMed1999

Lactose malabsorption and rate of bone loss in older women.

OBJECTIVES: to study the prevalence of lactose malabsorption with increasing age and to determine whether lactose malabsorbers consume less dietary calcium, have lower bone mineral density or display faster bone loss than lactose absorbers. DESIGN: 80 healthy Caucasian women aged 40-79 years (20 per decade) were studied for 1 year. METHODS: breath hydrogen exhalation was measured for 3 after a 50 g oral lactose challenge. Bone density was assessed in the radius, femoral neck, lumbar spine and total body by dual energy x-ray absorptiometry and dietary calcium intake was estimated by 4-day diet records and food-frequency questionnaires. RESULTS: lactose malabsorption rose with age (15% in those aged 40-59 years versus 50% in those aged 60-79; P < 0.01). Malabsorbers aged 70-79 years consumed significantly less calcium than lactose absorbers of this age (P < 0.05). Baseline total body calcium values were lower in lactose malabsorbers (n=26) than in lactose absorbers (n=54) but age-adjustment eliminated this difference. Bone change (% per year) was correlated with dietary calcium intake at the femoral neck and trochanter (P < 0.05) but was not statistically greater in malabsorbers than in absorbers. CONCLUSIONS: the ability to absorb lactose declines in the 7th decade. This may contribute to decreased dietary intakes of milk products and calcium in elderly women. However, lactose malabsorption without reduction in calcium intake has little effect on bone mineral density or the rate of bone loss.

Adult↗

PubMed1999

Evaluating Tackling Rugby Injury: the pilot phase for monitoring injury.

OBJECTIVE: To assess the suitability of two previously unused data sources for monitoring rugby injury throughout New Zealand. METHOD: Interviews were conducted with respondents sampled from players registered with the Rugby Football Unions (RFUs) and players claiming for rugby injuries from the Accident Rehabilitation and Compensation Insurance Corporation (ACC) in Auckland and Dunedin. RESULTS: Of the 500 RFU players sampled, 63% were interviewed and of these 39 (12%) had been injured playing rugby union. Of the 456 ACC claimants sampled, 66% were interviewed and 265 (88%) had been injured playing rugby union. CONCLUSION: Identifying injured players through ACC claims was more efficient, both procedurally and because a smaller sample size was required to detect changes in incidence. IMPLICATIONS: With no routine surveillance of sports injury being undertaken, recording sporting codes in national injury surveillance systems would assist the monitoring of sports injury.

Adolescent↗

PubMed1999

Use of duvets and the risk of sudden infant death syndrome.

BACKGROUND: The use of duvets in infancy is not recommended in the UK and Australia because of a reported association with sudden infant death syndrome (SIDS). AIMS: To examine the association between the use of duvets and the risk of SIDS. METHODS: A nationwide case control study (393 cases, 1592 controls). The use of duvets was assessed by interview with the parent or guardian. RESULTS: The use of duvets was associated with an increased risk of SIDS (odds ratio (OR) = 1.65; 95% confidence interval (CI), 1.31 to 2.08); however, after adjustment for potential confounders there was no increased risk of SIDS (OR = 1.04; 95% CI, 0.77 to 1.38). Furthermore, subgroup analysis did not identify any group in which the use of duvets was associated with an increased risk of SIDS. CONCLUSIONS: This study does not support the recommendation to avoid duvets.

Bedding and Linens↗

PubMed1999

Validity of self reported crashes and injuries in a longitudinal study of young adults.

OBJECTIVES: The aim of this study was to determine the validity of self report as a source of information on crashes and injuries. SETTING: This study was part of the Dunedin Multidisciplinary Health and Development Study (DMHDS), which is a longitudinal study of the health, development, and behaviour of a cohort of young New Zealanders. METHOD: At the age 21 assessment DMHDS study members were asked to report serious injury and motor vehicle traffic crashes experienced over the previous three years. The self reported injuries were compared with the New Zealand Health Information Service (NZHIS) public hospital discharge file to determine the completeness of the self reported data. The traffic crashes were compared with the police traffic crash reports to determine the accuracy of self reported crash details. RESULTS: Twenty five (86%) of the 29 unintentional injuries, six (67%) of the nine assaults, and one (14%) of the six self inflicted injuries on the NZHIS file were self reported. The level of agreement between the self reported crash details and those recorded on the traffic crash report was high. CONCLUSIONS: The results show that self reports can be a useful and valid source of injury and crash data.

Accidents, Traffic↗

PubMed1999

Phylogeny of the tropical tree family Dipterocarpaceae based on nucleotide sequences of the chloroplast RBCL gene.

The Dipterocarpaceae, well-known trees of the Asian rain forests, have been variously assigned to Malvales and Theales. The family, if the Monotoideae of Africa (30 species) and South America and the Pakaraimoideae of South America (one species) are included, comprises over 500 species. Despite the high diversity and ecological dominance of the Dipterocarpaceae, phylogenetic relationships within the family as well as between dipterocarps and other angiosperm families remain poorly defined. We conducted parsimony analyses on rbcL sequences from 35 species to reconstruct the phylogeny of the Dipterocarpaceae. The consensus tree resulting from these analyses shows that the members of Dipterocarpaceae, including Monotes and Pakaraimaea, form a monophyletic group closely related to the family Sarcolaenaceae and are allied to Malvales. The present generic and higher taxon circumscriptions of Dipterocarpaceae are mostly in agreement with this molecular phylogeny with the exception of the genus Hopea, which forms a clade with Shorea sections Anthoshorea and Doona. Phylogenetic placement of Dipterocarpus and Dryobalanops remains unresolved. Further studies involving representative taxa from Cistaceae, Elaeocarpaceae, Hopea, Shorea, Dipterocarpus, and Dryobalanops will be necessary for a comprehensive understanding of the phylogeny and generic limits of the Dipterocarpaceae.

Journal Article↗

PubMed1999

The Xerostomia Inventory: a multi-item approach to measuring dry mouth.

OBJECTIVE: To develop a valid multi-item method of measuring the symptoms of xerostomia which includes the wide range of xerostomia symptoms in a single quantitative measure. DESIGN: A combination of qualitative and quantitative approaches. SETTING: A cohort study in South Australia. PARTICIPANTS: Older people aged 65 years or more who were taking part in the South Australian Dental Longitudinal Study. MEASURES: Xerostomia symptoms were evaluated using a multi-item inventory format and, for comparison purposes, a standard single dry-mouth question. Resting whole-salivary flow rate was estimated using the 'spit' method. RESULTS: Xerostomia and flow-rate data were available for 636 individuals. Factor analysis revealed the presence of a discrete xerostomia dimension, represented by 11 items whose responses were summated to give a single Xerostomia Inventory (XI) scale score. This had a very low correlation with resting flow rate but a much stronger, positive correlation with the standard dry-mouth question responses. CONCLUSIONS: The XI shows adequate content and concurrent validity, and appears to be a promising advance on previous approaches to xerostomia symptomatology although further testing is required.

Aged↗

PubMed1998

The influence of depicted illumination on brightness.

The striking illusions produced by simultaneous brightness contrast generally are attributed to the center-surround receptive field organization of lower order neurons in the primary visual pathway. Here we show that the apparent brightness of test objects can be either increased or decreased in a predictable manner depending on how light and shadow are portrayed in the scene. This evidence suggests that perceptions of brightness are generated empirically by experience with luminance relationships, an idea whose implications we pursue in the accompanying paper.

Computer Graphics↗

PubMed1998

An empirical explanation of brightness.

In this second part of our study on the mechanism of perceived brightness, we explore the effects of manipulating three-dimensional geometry. The additional scenes portrayed here demonstrate that the same luminance profile can elicit different sensations of brightness as a function of how the objects in the scene are arranged in space. This further evidence confirms the implication of the scenes presented in the accompanying paper, namely that sensations of relative brightness-including standard demonstrations of simultaneous brightness contrast-cannot arise by computations of local contrast. The most plausible explanation of the full range of perceptual phenomena we have described is an empirical strategy that links the luminance profile in a visual stimulus with an association (the percept) that represents the profile's most probable real-world source.

Contrast Sensitivity↗

PubMed1998

Repression of transcription initiation by Escherichia coli FNR protein: repression by FNR can be simple.

Naturally occurring promoters that are repressed by the Escherichia coli FNR protein are complex. In this work, we have constructed a simple semi-synthetic promoter that is repressed by FNR binding to a single site that overlaps the promoter -35 element. Our results show that a single site for FNR is sufficient for effective repression. This semi-synthetic promoter provides a simple tool for monitoring FNR binding to target sites in the absence of its activation function. We have exploited this to study FNR mutants that are defective in repressing the ndh promoter, a complex naturally occurring promoter that is repressed by FNR.

Bacterial Proteins↗

PubMed1998

Methyl-deficient diets, methylated ER genes and breast cancer: an hypothesized association.

Recent molecular studies show that ER-negative breast cancer results from the lack of ER gene transcription due to the methylation of the CpG island 5' to the gene. Because CpG island methylation is an early event in carcinogenesis and because methyl-deficient diets could result in CpG island methylation, it is relevant to postulate that methyl-deficient diets may be a risk factor for breast cancer with methylated ER genes (as opposed to the disease with unmethylated ER genes). This molecular-based etiologic hypothesis may facilitate epidemiological research on the relationship between breast cancer and diet that has been unclear until now.

Breast Neoplasms↗

PubMed1998

Body mass index, waist girth, and waist-to-hip ratio as indexes of total and regional adiposity in women: evaluation using receiver operating characteristic curves.

Receiver operating characteristic (ROC) curves were constructed to assess the value of body mass index (BMI) as a screening measure for total adiposity and to examine waist-to-hip ratio (WHR) and waist circumference as measures of central fat distribution. Body fat reference measurements were determined by dual-energy X-ray absorptiometry (DXA). The study population comprised 96 healthy white women aged 16-80 y. A positive reference test was defined as a result at or above the 75th percentile for our study population for all DXA measurements. Sensitivity and specificity were calculated at several percentile cutoffs for BMI, WHR, and waist girth. The areas under the ROC curves were calculated to compare the relative ability of each anthropometric technique to correctly classify subjects according to the reference measurement for that technique. BMI (our 75th percentile = 27.3) performed well as a screening measure of total adiposity, correctly identifying 83% of subjects with a high body fat mass while misclassifying only eight subjects [four false-negatives (subjects with high fat mass who were in the low BMI category) and four false-positives (subjects with a low fat mass who were in the high BMI category)]. The screening performance of WHR (our 75th percentile = 0.81) was lower, accurately categorizing 58% of subjects while misclassifying 28 subjects. By contrast, waist circumference (our 75th percentile = 86.9 cm) was significantly better than WHR at screening for regional fat distribution, accurately classifying 83% of subjects and misclassifying eight subjects (P < 0.05). We conclude that BMI and waist circumference provide simple yet sensitive methods for the estimation of total and central adiposity in groups of adult women.

Absorptiometry, Photon↗

PubMed1998

Widespread origin of the primate mesofrontal dopamine system.

The dopaminergic innervation of the frontal cortex, commonly implicated in psychiatric and neurological disorders, has traditionally been associated with a circumscribed midline group of ventral tegmental area (VTA) neurons. We have employed a combination of retrograde tracing, using fluorescent dyes, and tyrosine hydroxylase (TH) immunohistochemistry to amplify knowledge of frontal cortex-projecting dopamine (DA) neurons in non-human primates. Injections of retrograde fluorochromes were made in areas 46, 8B/6M, 12, 4, 24, and the prelimbic (PL) and infralimbic areas (IL) of the rhesus monkey. The mesencephalic distribution of neurons exhibiting both retrograde labeling and TH immunoreactivity or retrograde labeling alone was examined from the level of the mammillary bodies to the locus coeruleus. DA afferents innervating the macaque frontal cortex as a whole originate from an unexpectedly widespread continuum of neurons distributed in the dorsal aspects of all three of the mesencephalic DA cell groups [A9, A10 and A8; generally corresponding to the DA cells of the substantia nigra (SN), VTA, and the retrorubral area (RRA) respectively]. A large number of these retrogradely labeled neurons are non-dopaminergic. The dorsal frontal cortex (areas 46, BB/6M and 4) receive DA projections primarily from the full medial-lateral extent of A9 cells dorsal to the SN pars compacta (i.e. A9 dorsalis), the RRA and to a lesser extent from the A10 parabrachial pigmented nucleus (PBPG) and linear nuclei, the latter of which have been associated with the mesocortical DA system. In contrast, the ventromedial PL and IL exhibit a significantly more robust input from the PBPG and midline linear VTA nuclei than from the lateral groups. The anterior cingulate cortex (area 24) is innervated by a group of DA neurons primarily located between these laterally and medially concentrated populations. These findings demonstrate a degree of compartmentalization of the mesofrontal DA system in primates, and suggest that this projection should no longer be viewed as a unitary midline system.

Amidines↗

PubMed1998

Bone mineral density in girls with forearm fractures.

In childhood, the most common site of fracture is the distal forearm. To determine whether young girls with these fractures have low bone density more commonly than fracture-free controls, we measured bone density at the radius, spine, hip, and whole body and total body bone mineral content, lean tissue mass, and fat mass by dual-energy X-ray absorptiometry in 100 Caucasian girls aged 3-15 years with recent distal forearm fractures and 100 age- and gender-matched controls. Bone density (age-adjusted ratios of all cases:controls with 95% confidence intervals) was lower in cases at the ultradistal radius 0.963 (0.930-0.996), 33% radius 0.972 (0.945-0.999), lumbar spine 0.945 (0.911-0.980), hip trochanter 0.952 (0.918-0.988), and total body 0.978 (0.961-0.995). Moreover, osteopenia (defined as Z score below -1), was more common in cases than controls (p < 0.05) in the forearm, spine, and hip, with one third of fracture cases having low spinal density. Odds ratios (95% confidence intervals) for low bone density were: ultradistal radius, 2.2 (1.1-4.6); lumbar spine, L2-L4, 2.6 (1.3-4.9); and femur trochanter, 2.0 (1.0-3.9). Fracture patients aged 8-10 years weighed more (mean +/- SD) than age-matched controls (37.2+/-8.0 kg vs. 32.5+/-6.6 kg, p < 0.01) while older patients reported lower current and past calcium intakes than matched controls (p < 0.05). We conclude that low bone density is more common throughout the skeleton in girls with forearm fractures than in those who have never broken a bone, supporting the view that low bone density may contribute to fracture risk in childhood.

Adolescent↗

PubMed1997

Transcription activation at class I FNR-dependent promoters: identification of the activating surface of FNR and the corresponding contact site in the C-terminal domain of the RNA polymerase alpha subunit.

A library of random mutations in the Escherichia coli fnr gene has been screened to identify positive control mutants of FNR that are defective in transcription activation at Class I promoters. Single amino acid substitutions at D43, R72, S73, T118, M120, F181, F186, S187 and F191 identify a surface of FNR that is essential for activation which, presumably, makes contact with the C-terminal domain of the RNA polymerase alpha subunit. This surface is larger than the corresponding activating surface of the related transcription activator, CRP. To identify the contact surface in the C-terminal domain of the RNA polymerase alpha subunit, a library of mutations in the rpoA gene was screened for alpha mutants that interfered with transcription activation at Class I FNR-dependent promoters. Activation was reduced by deletions of the alpha C-terminal domain, by substitutions known to affect DNA binding by alpha, by substitutions at E261 and by substitutions at L300, E302, D305, A308, G315 and R317 that appear to identify contact surfaces of alpha that are likely to make contact with FNR at Class I promoters. Again, this surface differs from the surface used by CRP at Class I CRP-dependent promoters.

Bacterial Proteins↗

PubMed1997

ERCP: a review of technical competency and workload in a small unit.

BACKGROUND: ERCP is increasingly performed not only in large referral centers but also in smaller units. We sought to analyze the success rates of selective cannulation and intervention using the cumulative sum method and to document the workload in a small unit. METHODS: Indications, results, and interventions performed by one endoscopist were recorded for all patients undergoing ERCP at Dunedin Hospital. Selective cannulation and successful intervention were used as outcome measures and, using the cumulative sum method, compared to a target value of 90%. RESULTS: Over an 8-year period, 532 ERCPs were performed. Overall 91% and 81% of selective cannulation and interventions respectively, were successful. The cumulative sum method plot shows that satisfactory outcomes for selective cannulation were obtained after some 100 to 120 procedures and after some 120 interventions. ERCP was normal in 171 (32%) patients, stones were found in 169 (32%), and strictures in 81 (15%) patients. CONCLUSIONS: The cumulative sum method is a valuable tool to compare individual performance with a nominated target value and to ensure that an acceptable outcome is achieved and maintained. These results show that small units can develop and maintain expertise in ERCP if procedures are performed regularly.

Adolescent↗

PubMed1997

Tomoxiprole selectively inhibits cyclooxygenase-2.

Tomoxiprole is a nonsteroidal anti-inflammatory compound that was reported to have low ulcerogenic potential, a quality that would be expected of a cyclooxygenase-2-selective inhibitor, and, in fact, we find it is selective for this isozyme. In stably transfected COS cells, the compound inhibits recombinant human cyclooxygenase-2 (IC50 = 7 nM) more potently than recombinant cyclooxygenase-1 (IC50 = 240 nM), and similar results are obtained with partially pure ovine enzyme preparations. The compound is thus a very potent as well as selective inhibitor of cyclooxygenase-2. As is true of some other cyclooxygenase-2-selective inhibitors, tomoxiprole inhibition of cyclooxygenase-2 but not cyclooxygenase-1 is time-dependent.

Animals↗

PubMed1997

Estrogen receptor status of breast cancer: a marker of different stages of tumor or different entities of the disease?

Breast cancer can be divided into two types according to the estrogen receptor (ER) level of the tumor: ER-positive and ER-negative. Two hypotheses have been raised about the relationship between ER-positive and ER-negative breast tumors. One hypothesis considers ER status as an indicator of a different stage of the disease. The other regards ER-positive and ER-negative tumors as different entities. For both etiological and biological studies of breast cancer it is important to know which hypothesis is correct. In this paper, we review evidence for and against each hypothesis and suggest issues to be addressed in future studies.

Biomarkers, Tumor↗

PubMed1997

The accuracy and completeness of childhood cancer registration in New Zealand.

The New Zealand Cancer Registry (NZCR) is the main source of data on cancer incidence in New Zealand. The accuracy and completeness of registration of childhood cancers (ages zero to 14 years) were assessed during the conduct of a case-control study. Newly diagnosed children (1990-93) were ascertained from three sources: the NZCR; the Patient Management System (hospital admissions and discharges); and the separate Children's Cancer Registry. Pathology reviews were conducted to verify the diagnoses. Capture-recapture methods were used to assess the completeness of ascertainment. During the four-year period, 409 incident cases of childhood cancer were confirmed, giving an age-standardized incidence rate of 131 per million person-years (95 percent confidence interval = 119-144). The NZCR ascertained 395 (97 percent) of these children. In addition, the NZCR notified us of 43 other 'childhood cancer' registrations which were not confirmed as new cases of childhood cancer according to our eligibility criteria. The main reasons for these were coding errors (20 registrations), duplicates (seven), and a change in the pathological diagnosis as a result of the pathology review (seven). The capture-recapture estimate of the total number of incident cases was 410. Overall, the NZCR had good completeness for childhood cancers, but the number of unconfirmed registrations was larger than expected.

Adolescent↗