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Biomedical subjects

L Parker

Publications and source records attributed to L Parker.

At least 19 recordsLinked to original sources
PubMed2000

Individual variation in somatic mutations of the glycophorin-A gene in neonates in relation to pre-natal factors.

The frequency of somatic mutations of the glycophorin-A (GPA) gene was measured in red blood cells from a series of newborn babies and related to various epidemiological and lifestyle factors in order to identify those factors that might influence the mutation rate before birth. Although there was substantial variation in the mutation frequencies between individual babies, no specific associations were found with any of the factors explored including smoking, age and social class of the parents, and gender and birth weight of the babies. It is concluded that these factors do not have a substantial effect on the mutational endpoint measured, although this does not necessarily mean that they have no effect on health risk to the offspring. The observed variation in GPA gene mutation frequency must, therefore, be due either to exposure to less obvious external influences or to intrinsic factors.

Adolescent↗
PubMed2000

Additive isotonic regression models in epidemiology.

Stone's method for assessing disease risk around a point source through isotonic regression is routinely used in spatial epidemiology. It is useful in situations where the relationship of risk with exposure (distance being commonly used as a surrogate variable) is assumed monotonic but otherwise of unknown form. This paper extends this method to non-spatial epidemiology, where typically two or more risk factors are present. The methodology described is based on the additive isotonic model approach of Bacchetti; versions appropriate to count (Poisson) data and case-control (binomial) data are described. In both cases, adjustment for covariates is incorporated, and a Monte Carlo method of hypothesis testing and interval estimation is presented. The methodology is illustrated through a case-control example concerning the analysis of the possible effect of preconceptional external ionizing radiation doses on the sex ratio at birth among children of fathers working at the Sellafield nuclear installation, Cumbria, U.K.

Case-Control Studies↗
PubMed2000

Risk of cardiovascular disease measured by carotid intima-media thickness at age 49-51: lifecourse study.

OBJECTIVE: To quantify the direct and indirect effects of fetal life, childhood, and adult life on risk of cardiovascular disease at age 49-51 years. DESIGN: Follow up study of the "Newcastle thousand families" birth cohort established in 1947. PARTICIPANTS: 154 men and 193 women who completed a health and lifestyle questionnaire and attended for clinical examination between October 1996 and December 1998. MAIN OUTCOME MEASURES: Correlations between mean intima-media thickness of the carotid artery (carotid intima-media thickness) and family history, birth weight, and socioeconomic position around birth; socioeconomic position, growth, illness, and adverse life events in childhood; and adult socioeconomic position, lifestyle, and biological risk markers. Proportions of variance in carotid intima-media thickness that were accounted for by each stage of the lifecourse. RESULTS: Socioeconomic position at birth and birth weight were negatively associated with carotid intima-media thickness, although only social class at birth in women was a statistically significant covariate independent of adult lifestyle. These early life variables accounted directly for 2.2% of total variance in men and 2.0% in women. More variation in carotid intima-media thickness was explained by adult socioeconomic position and lifestyle, which accounted directly and indirectly for 3.4% of variance in men (95% confidence interval 0.5% to 6.2%) and 7.6% in women (2.1% to 13.0%). Biological risk markers measured in adulthood independently accounted for a further 9.5% of variance in men (2.4% to 14.2%) and 4.9% in women (1.6% to 7.4%). CONCLUSIONS: Adult lifestyle and biological risk markers were the most important determinants of the cardiovascular health of the study members of the Newcastle thousand families cohort at age 49-51 years. The limited overall effect of early life factors may reflect the postwar birth year of this cohort.

Cardiovascular Diseases↗
PubMed2000

Prevertebral soft tissue swelling following trauma: usefulness following tube placement.

OBJECTIVE: Prevertebral soft tissue swelling (PVSTS) is an important marker of spinal trauma. In patients with missed or occult cervical fractures, it may be the only indication of serious injury. It has been anecdotally suggested that PVSTS is not useful following placement of a nasogastric (NGT) or endotracheal (ETT) tube because of possible iatrogenic trauma and/or soft tissue compression. Consequently, we investigated trauma patients for evidence of PVSTS, comparing radiographs performed before and after placement of NGTs and/or ETTs. DESIGN AND PATIENTS: PVSTS at the C2 and C6 levels was measured on lateral cervical spine radiographs in 102 patients with cervical spine fractures. Measurements were obtained in 66 patients before and after placement of either an NGT (23), ETT (8), or both an NGT and ETT (35). They were also obtained in 36 control patients with fractures and neither an NGT nor ETT, at presentation and after an interval temporally matched to that in the patients with tubes in place. RESULTS: The group with ETTs showed variable changes to PVSTS (31% increase, 63% decrease, and 6% no change). The group with NGTs also showed variable changes to PVSTS (33% increase, 53% decrease, and 13% no change). The group with ETTs and NGTs similarly showed variable changes to PVSTS (25% increase, 72% decrease, 3% no change). Surprisingly, the control group showed similar temporal changes without tube placement (49% increase, 36% decrease, 13% no change). Analyses using the one-tailed F-test of the ratio of the variance of the tube to non-tube groups and the Mann-Whitney test were performed. No significant difference was found in the prevertebral soft tissues at the C2 level between those with tubes in place and the control subjects. However, at the C6 level there was statistical significance between the groups with NGTs and both NGTs and ETTs versus the non-tube groups. Probability under the F-test for the groups with NGTs and both NGTs and ETTs was 0.001 and 0.005, respectively. Under the Mann-Whitney test, P values for groups with NGTs and both NGTs and ETTs were 0.0002 and 0.0001, respectively. CONCLUSION: The appearance of PVSTS showed variable and unpredictable changes following ETT, NGT, or combined ETT/NGT placement at the C2 level. This appears to be an artifact of temporal changes. However, at the C6 level, the presence of PVSTS following NGT or ETT and NGT placement (but not ETT placement alone) may be an accurate indirect sign of cervical spine injury.

Adolescent↗
PubMed2000

Comparison of fundamental and wideband harmonic contrast imaging of liver tumors.

Wideband harmonic imaging (with phase inversion for improved tissue suppression) was compared to fundamental imaging in vivo. Four woodchucks with naturally occurring liver tumors were injected with Imagent (Alliance Pharmaceutical Corp., San Diego, CA). Randomized combinations of dose (0.05, 0.2 and 0.4 ml/kg) and acoustic output power (AO; 5, 25 and 63% or MI < or = 0.9) were imaged in gray scale using a Sonoline Elegra scanner (Siemens Medical Systems, Issaquah, WA). Tumor vascularity, conspicuity and contrast enhancement were rated by three independent observers. Imagent produced marked tumor enhancement and improved depiction of neovascularity at all dosages and AO settings in both modes. Tumor vascularity and enhancement correlated with mode, dose and AO (P < 0.002). Fundamental imaging produced more enhancement (P < 0.05), but tumor vascularity and conspicuity were best appreciated in harmonic mode (P < 0.05). Under the conditions studied here, the best approach was wideband harmonic imaging with 0.2 ml/kg of Imagent at an AO of 25%.

Analysis of Variance↗
PubMed2000

Stillbirth risk with social class and deprivation: no evidence for increasing inequality.

The objective of this study was to determine whether inequality in stillbirth risk between social strata has changed over time. Subjects were all 288,869 births in Cumbria, northwest England, 1950-1993 and all 8,039,269 births in England and Wales, 1981-1992. Social class of Cumbrian babies was ascertained from birth registrations. Community deprivation scores were calculated from census data for (i) enumeration districts in Cumbria and (ii) county districts in England and Wales. The relative index of inequality was used to measure inequality of stillbirth risk between social strata. Results indicate inequality in stillbirth risk in Cumbria has fallen significantly since 1966 (P< or =0.02) and was not evident in more recent time periods. In England and Wales, there was significant inequality in stillbirth risk in all time periods and no evidence that this has changed over time. Inequality in stillbirth risk has not increased and in some areas has attenuated in recent years.

Adult↗
PubMed2000

Identification of maverick, a novel member of the TGF-beta superfamily in Drosophila.

The transforming growth factor-beta (TGF-beta) superfamily of structurally related ligands regulates essential signaling pathways that control many aspects of cell behavior in organisms across the phylogenetic spectrum. Here we report the identification of maverick (mav), a gene that encodes a new member of the TGF-beta superfamily in Drosophila. Phylogenetic analysis and sequence comparison suggest that Mav cannot be easily assigned to any one sub-family, since it is equally related to BMP, activin and TGF-beta ligands. mav maps to the fourth chromosome and is expressed throughout development. In situ hybridization experiments reveal the presence of maternally derived mav transcript in precellular blastoderm embryos. Later in development, mav is expressed in a dynamic pattern in the developing gut, both in endodermal and visceral mesodermal cells. In adult females, high levels of mav mRNA are present in late stage egg chambers.

Amino Acid Sequence↗
PubMed2000

Vitamin D receptor gene start codon polymorphism (FokI) and bone mineral density in healthy male subjects.

OBJECTIVE: The genetic factors determining peak bone mineral density (BMD) in men are not well characterized. Recent studies have investigated the relationship between the start codon polymorphism (SCP) of the vitamin D receptor (VDR) gene and BMD in different populations. We have now examined the relationship between SCP of the VDR gene and BMD in a group of healthy Caucasian men from the north-east of England. SUBJECTS: Ninety-six healthy men (median age 50, range 40.0-77.0 years). MEASUREMENTS: Analysis of the FokI genotypes of SCP of the VDR and measurements of BMD at the femoral neck and lumbar spine were performed. RESULTS: FF, Ff and ff VDR FokI genotypes were found to have the highest, intermediate and the lowest lumbar spine BMD, respectively (Mean +/- SD, for FF 1.07 +/- 0.14, Ff 1.05 +/- 0.16 and ff 0.95 +/- 0.10 g/cm2). There was a significant difference in spine BMD between FF and ff genotypes (P < 0.05, analysis of variance [ANOVA]), but no such difference was apparent between Ff and ff (P > 0.05, ANOVA). Interestingly, there was no association between FokI polymorphism and femoral neck BMD (Mean +/- SD, for FF 0.85 +/- 0.12, Ff 0.87 +/- 0.15 and ff 0.83 +/- 0.15 g/cm2). The distribution of FokI VDR genotypes approached Hardy-Weinberg equilibrium and was similar to that reported for women from different ethnic groups, as the prevalence of FF and ff genotypes was 44% and 16%, respectively. CONCLUSION: The study shows that in this population of healthy men there is a weak association between lumbar spine bone mineral density and FokI restriction fragment length polymorphism at the translation initiation site of the vitamin D receptor gene.

Adult↗
PubMed2000

Incidence and survival for cancer in children and young adults in the North of England, 1968-1995: a report from the Northern Region Young Persons' Malignant Disease Registry.

The Northern Region Young Persons' Malignant Disease Registry records information on young people under 25 years old diagnosed with cancer in the Northern Region of England. Incidence and survival rates were calculated for children and young adults diagnosed with cancer between 1968 and 1995. There were 2099 (M:F 1.28:1) children (age 0-14 years) and 2217 (M:F 1.23:1) young adults (15-24 years) diagnosed with a first cancer between 1968 and 1995. The age-standardized rate (ASR) for childhood cancer was 121 per million 0 to 14 year-olds per year. For young adults the ASR was 175 per million 15 to 24 year-olds, per year. Incidence of childhood cancer increased over time at a rate of 12 extra cases per million children, per decade (P < 0.001). In young adults incidence rates increased by 16 extra cases per million 15 to 24 year-olds, per decade (P < 0.001). For childhood cancer 5-year survival was 42% for those diagnosed 1968-1977, 57% for 1978-1987 and 71% (95% CI 67-75) for 1988-1995. Survival for young adults over the three periods was 45%, 62% and 73% (95% CI 70-78) respectively. The cumulative risk of developing cancer before the age of 25 is 1 in 285. Over the 28-year period there were significant improvements in survival and modest increases in incidence in both children and young adults.

Adolescent↗
PubMed2000

Parental recall of birth weight: how accurate is it?

OBJECTIVE: To assess the accuracy of parental recall of birth weight in a British population and to investigate whether social class and age of the child significantly influence the accuracy of recalled birth weight. METHODS: A questionnaire was given to parents whose children were participating in a blood pressure study and the hospital records were retrieved to check the birth weight data. RESULTS: At the time of the study, the children (n = 649) ranged in age from 6 to 15 years. Seventy five per cent of the recalled birth weights were within 50 g of that recorded in the hospital records. No significant associations were found between the difference in birth weights (recalled birth weight minus hospital record) and social class of the parents or age of the child at time of data collection. CONCLUSION: This large study shows that parental recall of birth weight is good across the social classes and up to 16 years after delivery. There was no evidence of systematic bias, which would prejudice results of studies on the relation of birth weight to adult hypertension.

Adolescent↗
PubMed2000

Proximity to maternity services and stillbirth risk.

A study of all 77 995 live births and 1234 stillbirths to mothers living in West Cumbria from 1950 to 1989 found no significant increase in stillbirth risk with distance of mother's residence from the first or second nearest maternity services, after allowing for year of birth, father's social class, and birth order.

England↗
PubMed2000

Endometrial polyps: MR imaging features and distinction from endometrial carcinoma.

PURPOSE: To determine the magnetic resonance (MR) imaging characteristics of endometrial polyps and the accuracy of MR imaging in distinguishing endometrial polyps from endometrial carcinomas in a case-control study. MATERIALS AND METHODS: Cross-referencing pathology records with MR studies from two institutions disclosed 35 patients with surgically proved endometrial polyp or carcinoma after controlling for tumor size. All MR examinations were performed at 1.5 T with T2-weighted fast spin-echo sequences in multiple planes. Three independent readers blinded to histologic diagnoses and clinical data scored each image for the presence of several defined findings. RESULTS: A central fibrous core (low signal intensity on T2-weighted images) and intratumoral cysts (high signal intensity on T2-weighted images) were seen more frequently in endometrial polyps than in carcinomas; myometrial invasion and necrosis showed high predictive value for carcinomas. The readers' responses showed a mean sensitivity of 79%, specificity of 89%, accuracy of 86%, positive predictive value of 82%, and negative predictive value of 88% for diagnosis of carcinoma. The mean area under the receiver operating characteristic curve for the three readers was 0.87 for the diagnosis of carcinoma. CONCLUSION: MR images can help to distinguish most polyps from endometrial carcinomas on the basis of morphologic features. Accuracy does not appear to be sufficient to obviate biopsy, partly because carcinomas and polyps frequently coexist.

Adult↗
PubMed2000

Can imaging findings help differentiate spinal neuropathic arthropathy from disk space infection? Initial experience.

PURPOSE: To determine if radiographic, computed tomographic (CT), and magnetic resonance (MR) imaging findings can help differentiate spinal neuropathic arthropathy from disk space infection. MATERIALS AND METHODS: Imaging studies in 33 patients were evaluated, including 14 patients with spinal neuropathic arthropathy (12 radiographic, seven CT, and six MR studies) and 19 with disk space infection (13 radiographic, nine CT, and 12 MR studies). Potential imaging discriminators, including endplate sclerosis or erosions, osteophytes, spondylolisthesis, facet involvement (narrowing or erosions), vacuum disk, paraspinal soft-tissue mass, joint disorganization, and osseous joint debris, were recorded, as were MR imaging signal intensity and gadolinium-enhancement characteristics. RESULTS: The most helpful findings for diagnosis of spinal neuropathic arthropathy were vacuum disk on radiographs and CT images, debris on radiographs and CT and MR images, disorganization on radiographs and CT and MR images, facet involvement on radiographs and CT and MR images, spondylolisthesis on CT and MR images, diffuse signal intensity patterns in vertebral bodies on MR images, and rim enhancement of disks on gadolinium-enhanced MR images. Findings that were not helpful included endplate sclerosis and erosions, osteophytes, paraspinal soft-tissue mass, and decreased disk height. CONCLUSION: Vacuum disk, facet involvement, vertebral body spondylolisthesis, joint disorganization and debris, and gadolinium-enhancement patterns of vertebral bodies and disks may help differentiate spinal neuropathic arthropathy from infection.

Adult↗
PubMed2000

Role of emergency medicine physicians in US performed in patients in the emergency department: how substantial is their participation?

PURPOSE: To determine the extent to which emergency medicine physicians have assumed responsibility for performing and interpreting ultrasonographic (US) studies in emergency departments (EDs) in the United States. MATERIALS AND METHODS: The national 1997 Medicare Part B database was searched by using standard US procedure codes, location codes, and physician specialty codes. The authors determined how many US studies were performed in EDs and what percentage of those studies were performed by emergency medicine physicians, radiologists, or other physicians. RESULTS: During 1997, 234,820 ED US studies within nine major examination categories were performed in Medicare patients nationwide. Emergency medicine physicians performed 1,551 (0.7%) of these studies. When echocardiographic examinations were excluded, emergency medicine physicians performed 458 (0.2%) of the remaining total of 196,158 studies. CONCLUSION: Although emergency medicine physicians have claimed to be actively involved in ED US on a broad scale, the data reveal that their involvement in 1997 was minimal. This raises doubt as to whether they can properly train their residents to perform US or maintain their own competence at acceptable levels.

Emergency Medicine↗
PubMed2000

The relationship of clinical and academic productivity in a university hospital radiology department.

OBJECTIVE: The purpose of this study was to evaluate the relationship between clinical and academic productivity over a 2-year period in a university hospital radiology department. MATERIALS AND METHODS: Clinical productivity, as determined by the number of total professional relative value units generated, was compared with academic productivity, which was determined by the number of published peer-reviewed articles, published non-peer-reviewed articles, published abstracts, and presentations delivered by each full-time clinical faculty member. The relationships of age, academic rank, administrative position, and division within the department were also assessed for their effect on relative value units and academic productivity. RESULTS: We found a significant inverse relationship between relative value units and the number of published peer-reviewed articles, published abstracts, and presentations. Age, academic rank, and administrative responsibilities had no effect on the number of relative value units. Faculty in the neuroradiology and cardiovascular-interventional radiology divisions generated more relative value units than did other faculty members. CONCLUSION: Faculty members with higher levels of clinical productivity showed significantly lower levels of academic productivity. This finding is consistent with the idea that increases in the clinical workload may diminish research output.

Adult↗
PubMed1999

Stillbirths among offspring of male radiation workers at Sellafield nuclear reprocessing plant.

BACKGROUND: Ionising radiation is a known mutagen, but few studies have examined transgenerational effects of paternal exposure in human beings. The workforce at the Sellafield nuclear reprocessing plant in the county of Cumbria, UK, is the most highly exposed workforce in western Europe and North America. This study, which is part of a larger programme of work investigating the health of the children of the Sellafield workforce, set out to find whether there was evidence of an association between stillbirth risk and paternal exposure to ionising radiation. METHODS: We collected details from birth registration documents for all singleton 248,097 livebirths and 3715 stillbirths in the county of Cumbria 1950-89. Within this cohort the 130 stillbirths and 9078 livebirths to partners of male radiation workers employed at Sellafield were identified. Logistic regression was used to analyse the relation between stillbirth risk and father's preconceptional radiation exposure, with adjustment for social class, year of birth, father's age, and birth order. FINDINGS: A significant positive association was found between the risk of a baby being stillborn and the father's total exposure to external ionising radiation before conception (adjusted odds ratio per 100 mSv 1.24 [95% CI 1.04-1.45], p=0.009). The risk was higher for stillbirths with congenital anomaly and was highest for the nine stillbirths with neural-tube defects. The statistical models predicted that, were the association to be interpreted as causal, between 0 and 31.9 of the 130 stillbirths to the workforce may be attributable to father's radiation exposure. INTERPRETATION: The findings of an increased risk of stillbirth with increasing paternal occupational exposure to external radiation are qualitatively consistent with those from animal models, though the risk estimate is higher. Although we cannot exclude the possibility of an unmeasured risk factor for stillbirth, confounded with paternal preconceptional irradiation, extensive checks confirmed that the statistical models were a good fit to the data and there was not statistical evidence of unmeasured factors.

Adult↗