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Biomedical subjects

K Walsh

Publications and source records attributed to K Walsh.

At least 253 records · Page 14Linked to original sources
PubMed1990

Pulse oximetry: a new non-invasive assessment of peripheral arterial occlusive disease.

Peripheral skin perfusion reflects the level of vascularity and viability of a limb and may help in planning the site of amputation or bypass surgery in patients with vascular disease. This study used peripheral pulse oximetry in 20 healthy volunteers and in 20 patients with limb ischaemia. Pulse oximetry saturation levels (Psa,O2) were compared with ankle artery Doppler pressures and transcutaneous oxygen measurements (Ptc,O2). Recordings were taken at two standard sites distally and referenced to finger and forearm to calculate an index. A significant correlation was found between Ptc,O2 and Psa,O2 in patients with ischaemia (r = 0.68, P less than 0.01). A further group of 12 patients with acute limb ischaemia was similarly assessed before and after revascularization. After revascularization mean(s.d.) Ptc,O2 increased from 38(13) to 44(1) mmHg (P greater than 0.05) and mean(s.d.) Psa,O2 increased from 86(3) to 90(4) per cent (P less than 0.01). These data suggest that pulse oximetry is a more sensitive index of peripheral perfusion than Ptc,O2 or ankle artery Doppler pressure and that, because of its accuracy and simplicity, it merits further use.

Angioplasty, Balloon↗
PubMed1990

AIDS/HIV infection.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

A comparison of UV cross-linking and vacuum baking for nucleic acid immobilization and retention.

The effectiveness of UV cross-linking and in vacuo baking for the immobilization and retention of DNA to various solid supports was investigated. Optimal immobilization treatments for supported and unsupported nitrocellulose and nylon membranes were: UV cross-linking at 254 nm with an exposure of 120 milliJoules/cm2, or baking in vacuo for two hours at 80 degrees C. UV-immobilized nitrocellulose-based membranes showed no increase in sensitivity when compared to baked membranes. An increase in sensitivity was observed for UV-immobilized nylon membranes as compared with baked nylon membranes in some instances, although this varied within lots of the membranes tested. Repeated strippings and heterologous reprobings resulted in loss of target DNA from UV-immobilized nylon membranes as compared to baked nylon membranes. Loss of target DNA from UV-immobilized nitrocellulose-based membranes due to repeated strippings and reprobings was even more pronounced. In vacuo baking of supported and unsupported nitrocellulose and nylon membranes was more effective for immobilization, and more importantly, for retention of target DNA through many reprobings of the same blot.

Collodion↗
PubMed1989

Dietary calcium, physical activity, and risk of hip fracture: a prospective study.

OBJECTIVE: To determine whether low dietary calcium intake and physical inactivity are risk factors for hip fracture among subjects aged 65 and over. DESIGN: Fifteen year follow up study of a large cohort of randomly selected elderly people living in the community, who had taken part in the 1973-4 survey of the Department of Health and Social Security, and for whom dietary and other data were recorded at initial interview and medical assessment. SETTING: Eight areas in Britain (England (five), Wales (one), and Scotland (two]. SUBJECTS: 1688 Subjects living in the community, of whom 1419 subjects (720 men and 699 women) agreed to participate. 1356 Subjects completed a seven day dietary record and 983 (542 men and 441 women) agreed to be assessed by a geriatrician. RESULTS: Incidence of hip fracture increased with age and was higher in women than men. Comparison with matched controls showed no evidence that the risk of hip fracture was related to calcium intake: the odds ratio for the lowest third of dietary calcium compared with the highest was 0.7 (95% confidence interval 0.1 to 3.9) after adjustment for smoking and body mass index. The adjusted odds ratio for the lowest third of outdoor activity compared with the highest was 4.3 (0.7 to 26.8), and that for grip strength was 3.9 (0.7 to 23.0). CONCLUSIONS: Reduced intake of dietary calcium does not seem to be a risk factor for hip fracture. Further evidence is provided that physical activity in the elderly protects against hip fracture.

Age Factors↗
PubMed1989

Rapid determination of sequence variations in actinidin isolated from Actinidia chinensis (var. Hayward) using fast atom bombardment mapping mass spectrometry and gas phase microsequencing.

A current limitation in the use of fast atom bombardment (FAB) mass spectrometric mapping of peptide mixtures, derived from enzymic digestion of proteins, is that most of the hydrophilic peptides are not observed. However, it has been demonstrated from previous work that esterification of the peptide mixture results in the detection of almost all peptides in FAB mass spectrometry. This strategy of FAB mapping was applied to the protein actinidin, isolated from an Italian variety of Actinidia chinensis. Two of the 12 tryptic peptides in FAB mass spectrometry did not exhibit molecular ions predicted from the known sequence of actinidin isolated from the New Zealand variety of A. chinensis. The two peptides were isolated by high-performance liquid chromatography, subjected to Staphylococcus aureus V8 protease digestion and sequenced by gas-phase microsequencing. Nine changes in amino acid composition were detected using the rapid and powerful combination of FAB mass spectrometric mapping and gas-phase microsequencing.

Amino Acid Sequence↗
PubMed1989

Cross-binding of factors to functionally different promoter elements in c-fos and skeletal actin genes.

A conserved 28-base-pair element in the skeletal actin promoter was sufficient to activate muscle-specific expression when placed upstream of a TATA element. This muscle regulatory element (MRE) is similar in structure to the serum response element (SRE), which is present in the promoters of the c-fos proto-oncogene and the nonmuscle actin genes. The SRE can function as a constitutive promoter element. Though the MRE and SRE differed in their tissue-specific expression properties, both elements bound to the same protein factors in vitro. These proteins are the serum response factor (SRF) and the muscle actin promoter factors 1 and 2 (MAPF1 and MAPF2). The SRF and MAPF proteins were resolved by chromatographic procedures, and they differed in their relative affinities for each element. The factors were further distinguished by their distinct, but overlapping, methylation interference footprint patterns on each element. These data indicate that the differences in tissue-specific expression may be due to a complex interaction of protein factors with these sequences.

Actins↗
PubMed1989

Occupational causes of low-back pain.

Associations between occupational activities and low-back pain (LBP) were examined in a retrospective postal survey of 545 randomly selected adults. Each subject gave a lifetime occupational history on six specified physical activities and also a lifetime history of LBP. Among the 436 subjects answering the questionnaire, the lifetime incidence of LBP was 63%. The occurrence of LBP was related by Cox's proportional hazards regression model to occupational activities in the year prior to the onset of symptoms. For the men the strongest associations were with heavy lifting and prolonged car driving. There was also an association with heavy lifting among the women. These risks were exaggerated in the subset of subjects whose LBP followed a chronic unremitting course. The findings are consistent with previous reports linking LBP with manual materials handling and driving at work. However, in this sample, less than 20% of the cases could be attributed to such activities.

Adult↗
PubMed1988

DNA-binding site for two skeletal actin promoter factors is important for expression in muscle cells.

Two nuclear factors bind to the same site in the chicken skeletal actin promoter. Mutations in the footprint sequence which eliminate detectable binding decrease expression in transfected skeletal muscle cells by a factor of 25 to 50 and do not elevate the low expression in nonmuscle cells. These results show that the factor-binding site contributes to the activation of expression in muscle cells and that it alone does not contribute significantly to repress expression in nonmuscle cells.

Actins↗
PubMed1987

Two nuclear factors compete for the skeletal muscle actin promoter.

We show that DNA fragments, which span the skeletal muscle alpha-actin promoter, form specific complexes with proteins from nuclear extracts of 11 different cultured cell types. These include two myocyte stage specific cell types, myoblast and myotube. The myocyte nuclear extracts are distinguished from all of the others by the electrophoretic mobility of the predominant DNA complex. This complex is greatly diminished in the nine non-myocyte cell types, where a different complex predominates. The major myocyte and non-myocyte complexes are caused by distinct binding activities that compete for the same DNA sequence element. DNA footprint analysis shows that this element is located 78 nucleotides upstream of the transcription start site, within a region that appears essential for expression in developing myocytes.

Actins↗
PubMed1987

Compensatory regulation in metabolic pathways--responses to increases and decreases in citrate synthase levels.

The level of citrate synthase was varied in Escherichia coli by recombinant DNA methods to elucidate regulatory interactions between the individual steps of the citric acid cycle. The effects of overproduction and underproduction of citrate synthase were assessed by measuring metabolite levels, rates of carbon flow, the phosphorylation state of isocitrate dehydrogenase, and the growth rate of the culture. This analysis revealed that the levels of citrate synthase and isocitrate dehydrogenase activity are co-ordinated for efficient growth on acetate. When citrate synthase was overproduced the isocitrate dehydrogenase reaction became rate limiting and prevented large increases in the flux through the citric acid cycle. Furthermore, changes in the level of citrate synthase were found to modulate the phosphorylation state of isocitrate dehydrogenase which regulates the distribution of carbon flow between the citric acid cycle and the glycoxylate shunt. These adjustments allowed the organism to maintain a relatively constant metabolic state despite changes in the level of a central metabolic enzyme. The interplay between citrate synthase and isocitrate dehydrogenase illustrates how living systems can compensate for variations in their internal environment.

Acetates↗
PubMed1986

Calcifying epithelial odontogenic tumours in three cats and a dog.

Neoplasms histologically similar to calcifying epithelial odontogenic tumour (CEOT) of man are described in three cats and a dog. The diagnostic features of these neoplasms are their occurrence in the jaw and the histological appearance of cords of epithelial cells, amyloid spherules and foci of calcification. The histogenesis and behaviour of the tumour are discussed.

Animals↗