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Biomedical subjects

J Parker

Publications and source records attributed to J Parker.

At least 127 records · Page 7Linked to original sources
PubMed1995

Fetal fibronectin in the cervicovaginal fluid of women with threatened preterm labour as a predictor of delivery before 34 weeks' gestation.

Fetal fibronectin (fFN) is an extracellular matrix protein found at the junction between fetal and maternal tissue. It has been hypothesized that fFN is released into cervicovaginal fluid prior to the onset of preterm labour and during episodes of threatened preterm labour (TPL). In the present study fFN was present in the cervicovaginal fluid of 31% (11/36) of patients with TPL. The presence of fFN was found to be predictive of delivery prior to 34 weeks' gestation in 36 patients presenting with TPL and intact membranes (sensitivity 100%, specificity 81%). Eleven patients had a positive fFN assay and 5 delivered before 34 weeks (positive predictive value (PPV) 46%). Twenty-five patients had a negative fFN result and none were delivered before 34 weeks (negative predictive value (NPV) 100%). Patients presenting with TPL who are fFN positive would be ideal candidates for intervention trials of tocolytics. It may be possible to delay or avoid immediate tocolysis and interhospital transfer in patients with a negative fFN immunoassay.

Body Fluids↗
PubMed1995

Classification of ductal carcinoma in situ by image analysis of calcifications from digital mammograms.

There is evidence to suggest that non-comedo cases of ductal carcinoma in situ (DCIS) may have a lower risk of progressing to invasive disease than comedo DCIS and may be managed with less radical treatment. Most cases of DCIS present as calcifications on the mammogram and, due to differences in the tumour architecture, comedo calcifications often have a characteristic linear or branching appearance. In this study, computer methods were developed to identify the comedo cases using the imaging features of individual calcifications and of calcification clusters. Classifier performance was measured using the area under the receiver operating characteristic (ROC) curve and was optimized by systematic testing of many different combinations of these features. On a test-set of 42 cases the computer achieved a ROC curve area of 0.91 using six combined cluster features. These results are encouraging given the observed overlap in appearance between the comedo and non-comedo cases.

Breast Diseases↗
PubMed1994

Health service costs of coronary angioplasty and coronary artery bypass surgery: the Randomised Intervention Treatment of Angina (RITA) trial.

For some patients with coronary artery disease, percutaneous transluminal coronary angioplasty (PTCA) is an alternative to coronary artery bypass grafting (CABG). We report comparative health service costs of these interventions within the Randomised Intervention Treatment of Angina (RITA) trial. Medications were costed at published UK prices; other resource use was costed with a set of unit costs estimated at two recruiting centres to the RITA trial, one in London and one outside. Over 2-year follow-up of 1011 patients, the estimated mean additional cost for those randomised to CABG compared with PTCA was 1050 pounds (95% CI 621 pounds-1479 pounds), with unit costs from the non-London centre, and 1823 pounds (1202 pounds-2444 pounds), with unit costs from the London centre. The initial average cost of treating a patient randomised to PTCA is about 52% of that of CABG, but after 2 years this increased to about 80% because of the greater need for subsequent interventions. The balance of advantage between PTCA and CABG may change after several years: funding has been obtained to continue RITA follow-up for 10 years. However, on the basis of patients' status at 2 years, the cost advantages of PTCA cannot be ignored. Further research is necessary to assess whether the advantage of PTCA in terms of cost is translated into one of cost-effectiveness.

Angina Pectoris↗
PubMed1994

Sequence and characterization of the Escherichia coli genome between the ndk and gcpE genes.

The region of the chromosome immediately upstream of the Escherichia coli gene gcpE has been cloned and sequenced. This region contains two functional open reading frames, orf 384 and orf 337, encoding proteins of 43,082 and 36,189 Da, respectively. Sequencing analysis (this paper) and the isolation of a DNA fragment containing a functional promoter (Talukder, A.A., Yanai, S., and Yamada, M. (1994) Biosci. Biotech. Biochem. 58, 117-120) indicate that orf 337 is in an operon with gcpE. The gene orf 384 is immediately downstream of the gene ndk, which encodes nucleoside diphosphate kinase.

Bacterial Proteins↗
PubMed1994

A ribosomal frameshifting error during translation of the argI mRNA of Escherichia coli.

Using fusions between the Escherichia coli genes argI and lacZ, it has been demonstrated that ribosomal frameshifting occurs at a frequency of between 3% and 16% within the argI mRNA, soon after the initiation codon. The frameshift involves a phenylalanyl-tRNA shifting into the +1 frame at the sequence UUU-U/C. The shift does not occur if the in-frame phenylalanine codon UUU is replaced by UUC. The level of frameshifting is higher in dense cultures and is not dependent on phenylalanine starvation. In the wild-type argI gene this frameshifting event would be an error, leading to a truncated, non-functional protein. Therefore, it is unlike the numerous examples of required frameshifting events that have been described in other genes.

Amino Acid Sequence↗
PubMed1994

Help from philosophy: responding to the animal rights challenge.

The chasm that C. P. Snow noted between the two cultures of science and the humanities may be part of an explanation for the success of the animal rights movement. Many philosophers, who represent the culture of the humanities, take an animal liberation position in the ethical debate about the use of animals in research. One who does not is Peter Carruthers. He presents a valuable critique of two important animal liberation ethicists, Tom Regan and Peter Singer, analyzing their thinking on the origins of ethical ideas and the source of ethical motivation. He identifies problems in their theories leading to conclusions that defy common sense about the value of human life. As an alternative, Carruthers introduces John Rawls' theory of contractualism. This theory provides a framework within which medical researchers and the public at large can defend the humane use of animals in research. His work promises to help bridge the gap between scientists and representatives of the humanities.

Animal Experimentation↗
PubMed1994

Glucose transporters (GLUT1, 2, & 4) in fat, muscle and liver in a rat model of endotoxic shock.

To explore the mechanisms for hypoglycemia in our rat model of septic shock, we examined whether changes occur in glucose transporter isoform protein level. Total membrane protein fractions were collected from tissues 6 to 8 hours after endotoxin injection at which time animals exhibited hypoglycemia (7.2 +/- 0.5 vs. 2.6 +/- 1.2mM) and lactacidemia (1.0 +/- 1.0 vs. 5.1 +/- 1.8mM/L) as compared to saline-treated controls. The protein level of glucose transporter isoforms GLUT1 and 4 in fat did not significantly change in septic shock when compared to control animals (126 +/- 22% and 114 +/- 79%, respectively). Likewise, no change was seen in GLUT1 or 4 in muscle (124 +/- 52% and 101 +/- 28%, respectively). The protein abundance of isoforms GLUT1 and 2 in liver were not significantly altered (123 +/- 35% and 101 +/- 23%, respectively). Septic shock induced hypoglycemia cannot be directly explained by changes in total glucose transporter protein levels.

Adipose Tissue↗
PubMed1994

Distribution of bone mineral density in the lumbar spine in health and osteoporosis.

The significance of variability in bone mineral density (BMD) between lumbar vertebrae L1 to L4 in the same individual was investigated by dual-energy X-ray absorptiometry in 1000 normal women aged 40-60 years (average 52 years) and 145 women aged 45-80 years (average 65 years) with vertebral osteoporosis. The mean BMD increased from L1 to L4 in normal women from 0.841 g/cm2 to 1.017 g/cm2, and in osteoporotics from 0.562 g/cm2 to 0.709 g/cm2. Z scores for osteoporotic women (Z = osteoporotic BMD - age-normal BMD/normal SD) were significantly lower for individual vertebrae compared with L1-4 and at L4 compared with L1, L2 and L3 (p < 0.001). The mean difference between Z scores for the highest and lowest vertebrae in an individual was 0.70 for normals (SD = 0.40) and 0.64 for osteoporotics (SD = 0.36). The mean Z score difference between the L1-4 Z score and the lowest individual vertebral Z score was 0.36 for normals (SD = 0.23) and 0.06 for osteoporotics (SD = 0.31). However, receiver operating analysis (ROC) curves showed that the lowest Z score for any individual vertebra did not provide improved discrimination between normals and osteoporotics when compared with the L1-4 Z score. The area under the ROC curve for L1-4 was significantly greater than for individual vertebrae (p < 0.05) and that for L4 was significantly smaller than for L1, L2 or L3 (p < 0.001). In conclusion, L1-4 BMD gives greater diagnostic sensitivity for osteoporosis than individual vertebrae, and L1, L2 and L3 are better than L4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Elastin degradation in the aorta of Watanabe hereditary hyperlipidemic rabbits.

The Watanabe hereditary hyperlipidemic (WHHL) rabbit is an animal model that resembles humans with familial hyperlipidemia. In the thoracic aortae, there is also morphologic evidence of marked destruction of medial lamellar elastin fibers. Herein is provided the chemical evidence of elastolytic degradation. The levels of lysyl oxidase (L.Ox.), soluble elastin (SE) and insoluble elastin (IE) were estimated in thoracic aortae samples from New Zealand white (NZW) and WHHL rabbits at 6 months of age or 5 WHHL rabbits at 2.5 years of age. Enzyme-linked immunosorption assays (ELISA) were used in the L.Ox. and SE measurements. IE was measured following alkali extraction of aortae. There was a decrease in IE in thoracic aortae from Watanabe rabbits compared to NZW controls at 6 months of age (P < 0.1), and a further loss of IE in aortae from 2.5-year-old WHHL rabbits relative to the values at 6 months (P < 0.05). Average values for IE were: 130 mg/g for 6-month-old NZW, 100 mg/g for 6-month-old WHHL, and 60 mg/g for 2.5-year-old WHHL rabbits. Moreover, SE was only observed in aorta extracts from the older WHHL rabbits, a sign of elastolytic damage. There was also a five- to sixfold decrease in L.Ox. in the older vs. younger rabbits.

Aging↗
PubMed1994

Quantitative evaluation of craniofacial changes with Jasper Jumper therapy.

Although the Jasper Jumper is becoming a widely accepted orthodontic appliance, no quantitative guidelines exist for therapy. The purpose of this investigation was to describe the orthopedic and orthodontic changes associated with Jasper Jumper therapy. A sample of 31 consecutively treated Class II patients was collected from three orthodontic practitioners who were using the same procedures and methods. Lateral cephalograms were taken immediately before appliance placement and immediately after appliance removal (mean interval of 0.4 years). The sample was case matched to untreated controls based on age, sex, and mandibular plane angle. The cephalograms were superimposed using anterior cranial base, maxillary, and mandibular reference structures to distinguish between growth/displacement and tooth movement. The results show that the majority of Class II correction was due to dental, rather than skeletal change. The maxilla underwent significant posterior displacement. The maxillary incisors retroclined and the maxillary molars tipped distally. Clockwise or backwards rotation was evident for the mandible. The mandibular incisors proclined significantly and the mandibular molars translated and tipped mesially. Jasper Jumper therapy is a valuable procedure for the correction of Class II dental malocclusions. Like all other treatment modalities, there are both indications and contraindications for its use.

Activator Appliances↗
PubMed1994

The protection of laboratory animals: a response to Stephenson.

This paper clarifies certain issues raised by Wendell Stephenson (The Journal of Medicine and Philosophy 18: 375-388, 1993) about research programs and animal care practices at the Oregon Regional Primate Research Center. It also responds to Stephenson's critique of the National Institute of Health's Guide for the Care and Use of Laboratory Animals. It identifies utilitarianism as the ethical theory underlying Stephenson's critique. Arguing that such an ethical theory is unworkable in addressing concerns about biomedical research and the use of animals, the paper defends the Guide's reliance on a wider tradition of ethical theories.

Animal Care Committees↗
PubMed1994

Post-menopausal vertebral osteoporosis: can dual energy X-ray absorptiometry forearm bone density substitute for axial measurements?

This study compared measurements of BMD using dual energy X-ray absorptiometry (DXA) at three sites in the nondominant forearm (ultradistal, distal one-third and a mid-region between these two), the lumbar spine (L1-L4) and the proximal femur (femoral neck, trochanter and Ward's triangle) for the evaluation of vertebral osteoporosis. Studies were performed on 100 normal women aged 29-69 yr (average 52 yr) and 63 osteoporotic women age 48-75 yr (average 66 yr) using the Hologic QDR-1000. Precision values of < 1% were obtained in both normal and osteoporotic women at both forearm and axial sites. Z-scores for the osteoporotics [Z = (mean BMD normal--mean abnormal)/S.D.] were--2.02 lumbar spine, -1.96 femoral neck, -1.79 ultradistal forearm, -1.73 mid region and -1.66 distal one-third forearm. Receiver operating characteristic curves showed that the lumbar spine and femoral neck equally discriminated between normals and osteoporotics with a 95% area under each curve, significantly greater values than those for the forearm which were 87% ultradistal, 89% mid forearm and 86% distal one-third forearm. Fracture thresholds, defined as the 90th centile of BMD for osteoporotic patients, were 1 S.D. below the normal mean for lumbar spine and femoral neck but equal to the mean for ultradistal, 0.6 S.D. below mean for mid region and 0.3 S.D. below mean for distal one-third region. We conclude that for the discrimination of normals and osteoporotic women the three forearm sites are comparable. However, both lumbar spine and proximal femur BMD are superior to all forearm sites.

Absorptiometry, Photon↗
PubMed1994

Eighth survey of staffing in cardiology in the United Kingdom 1992.

The Eighth Survey of Staffing in Cardiology was conducted with an index date of 30 September 1992. The total number of cardiologists in England and Wales, defined as individuals trained in the specialty and spending at least 40% of their professional time working in it, was 358. Of these 11 were part time, defined as six sessions or less, giving a number in whole time (or near whole time) equivalents of 352.5. The number of individuals increased from 1991 by 18 (5.3%). There were 71 cardiologists in Scotland and Northern Ireland, making a total for the United Kingdom of 429 individuals (423.5 whole time equivalents), which is 7.3 per million population. A total of 44 Districts serving 8.8 million people have no resident cardiologist. There has been little improvement since the 1991 survey. An additional 34 Districts with populations greater than 250,000 have only one cardiologist: we have clear evidence of inadequate provision of care in most of these, a situation that is inevitable within the resources provided. A wider threat to the provision of a satisfactory level of cardiological care throughout the United Kingdom will follow from changes in the organisation of the National Health Service and in the new requirements for training of future cardiologists because these changes will make major new demands on consultant time which cannot be met within existing resources. A crisis will be averted only if a rapid and major expansion of the consultant grade can be achieved.

Cardiology↗