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D Thomas

Publications and source records attributed to D Thomas.

At least 451 records · Page 25Linked to original sources
PubMed1994

Genetic studies of lactococcal bacteriophages--taxonomic differentiations and DNA analysis: evidence for 3' cohesive ends.

Twenty-four bacteriophages of Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris were classified. Two groups of bacteriophages morphologically defined as prolate or isometric types by electron microscopy were examined for their genome sizes, protein patterns and DNA homologies. These criteria showed that prolate phages are quite homogeneous. In contrast, isometric phages exhibit more differences, particularly in particle sizes and protein compositions. Analysis of DNA hybridizations confirmed that prolate phages can be grouped together as can be isometric phages but for one exception, phage I52. These two families were clearly defined. The unique phage which does not fit in either group probably belongs to a third one which is much less represented. No obvious relationships between these criteria and the lytic spectra were detected. Evidence of the presence of cohesive ends in phage genomes is also presented in this study. A more detailed analysis performed on one member of the prolate group revealed 3' protruding ends made up of around 13 nucleotides on complementary single strands.

Bacteriophages↗
PubMed1994

Screening for colorectal cancer using an immunochemical test for faecal occult blood: results of the first 2 years of a South Australian programme.

This paper reports an evaluation of the first 2 years of a South Australian screening programme for colorectal cancer which was established in 1988 by the Institute of Medical and Veterinary Science. The programme uses an immunochemical test for faecal occult blood. Based on 1 year of follow-up, over the period of this analysis there were 24 cancers and 99 adenomas detected in 6208 participants, and the estimated sensitivity and specificity of the test (for colorectal cancer) were 82.8 and 95.9%, respectively. In many cases the test was used to detect recurrence of disease in individuals with a previous diagnosis of colorectal cancer. The estimated predictive value of a positive test for colorectal cancer in this population was 7.5%. Results suggest that participants belonged to higher-than-average socio-economic groups and were more likely than the general population to have a family history of colorectal cancer. Almost one-third had suffered from bowel symptoms in the 6 months before taking the test. These unique characteristics of participants, which limit the generalizability of results to the wider population, may result from the programme's reliance on self-recruitment methods. Consistent evidence for improvements in mortality in populations screened for colorectal cancer is still required before a recommendation for widespread screening in Australia can be made.

Adult↗
PubMed1994

Diagnosis of ventricular tachycardia using a pacemaker Holter function.

The diagnosis of ventricular tachycardia (VT) using the Holter function of an implanted pacemaker has not yet been reported. We present the case of a patient with episodes of slow VT, hemodynamically stable, but in whom long lasting attacks were not identified by the patient as VT recurrences, finally leading to progressive heart failure. Prospective analysis of the 24-hour ECG and comparison with the pacemaker Holter data allowed us to determine diagnostic criteria to recognize VT using the pacemaker Holter function. Using these criteria it was possible to retrospectively diagnose VT occurrence during the weeks when the patient was out-of-hospital.

Aged↗
PubMed1994

Effects of the Nd:YAG laser and combined treatments on in vitro fibroblast attachment to root surfaces.

The purpose of this in vitro study was to evaluate the effects of the Nd:YAG laser either alone or in combination with root planning or air-powder abrasive treatment on fibroblast attachment to non-diseased root surfaces. 28, 4 x 4 mm root specimens and four disc-shaped root specimens 6 mm in diameter were obtained from unerupted 3rd molars. The root segments were randomly assigned to 4 treatment groups: (1) control; (2) laser-only treated; (3) laser treated followed by root planning; (4) laser treated followed by air-powder abrasive treatment. Laser-treated root specimens were exposed for 1 min with the Nd:YAG laser calibrated at an energy setting of 75 mJ at 20 pulses/s using a 320 microns contact fiber. The contact fiber was held parallel to the root segments and the root segments were kept moist with distilled water. Following the prescribed treatments, the root specimens were incubated with fibroblast cultures and then prepared for SEM examination. Results of cell counts of fibroblasts attached to specimens within each treatment group yielded the following means and standard deviations: control groups, 181.64 +/- 44.74; lased only, 78.57 +/- 21.35; lased and root planed 125.35 +/- 26.13; and lased followed by an air-powder abrasive, 177.28 +/- 55.71. Application of ANOVA followed by the Dunn Multiple Comparison test revealed significant differences (p < 0.01) in the number of attached cells between the control and laser-only treated groups; and between the laser-only and laser/air-powder abrasive treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1994

Food-purchasing behaviour in an Aboriginal community. 1. Results of a survey.

Attempts to improve the nutritional status of Aboriginal people through nutritional education programs should be informed by an understanding of contemporary patterns of food procurement, preparation and distribution. This paper describes the results of a survey of food-purchasing behaviour in a central-Australian Aboriginal community. Every transaction occurring in each food outlet in the community over a two-week period was recorded and the data analysed. The results show that women play a much greater role than men in food purchasing, that there is a significant recourse to takeaway foods, that there is a cycle of expenditure determined by distribution of pension and Community Development Employment Project cheques, and that children have sufficient disposable income to be able to provision themselves from the food outlets, so that much of their food consumption is not determined by adult members of their family.

Adolescent↗
PubMed1994

Mass analysis of biological macromolecular complexes by STEM.

Scanning transmission electron microscopy (STEM) provides a superbly versatile method of measuring the masses of macromolecular complexes ranging in size from single protein subunits to large virus particles. The physical basis of the method is the elastic scattering of electrons by the component atoms of the specimen. Unstained molecules yield a dark-field signal that is proportional to their local mass density, thus allowing direct measurements of the total mass of an individual particle, as well as of the masses of its resolved domains by integrating over appropriate regions of the image. In this review, we present an introduction to the STEM method of mass analysis from a practical standpoint, stressing the essential points of specimen preparation, as well as the scope and current limitations of the method. Its potentialities are illustrated by applications to several classes of macromolecules: isolated oligomeric proteins (the envelope glycoprotein of HIV), nucleoprotein complexes (SV40 minichromosome, transcription factor TFIIIC), membranous specimens (clathrin-coated membranes, the VDAC channel), and viruses (vesicular stomatitis virus; herpes simplex virus). In the case of multicomponent complexes, STEM mass measurements of both the intact complex and of defined biochemical derivatives (for instance, after extraction of specific components), allow one to compile complete and precise molecular inventories. Finally, we briefly anticipate future advances that should allow even more precise and detailed mass mappings, the labelling of specific sites with heavy atom clusters, and elemental mapping based on weak inelastic signals acquired in parallel with the relatively intense dark-field signals that have been so successfully exploited to date.

Animals↗
PubMed1994

Design and analysis of multilevel analytic studies with applications to a study of air pollution.

We discuss a hybrid epidemiologic design that aims to combine two approaches to studying exposure-disease associations. The analytic approach is based on comparisons between individuals, e.g., case-control and cohort studies, and the ecologic approach is based on comparisons between groups. The analytic approach generally provides a stronger basis for inference, in part because of freedom from between-group confounding and better quality data, but the ecologic approach is less susceptible to attenuation bias from measurement error and may provide greater variability in exposure. The design we propose entails selection of a number of groups and enrollment of individuals within each group. Exposures, outcomes, confounders, and modifiers would be assessed on each individual; but additional exposure data might be available on the groups. The analysis would then combine the individual-level and the group-level comparisons, with appropriate adjustments for exposure measurement errors, and would test for compatibility between the two levels of analysis, e.g., to determine whether the associations at the individual level can account for the differences in disease rates between groups. Trade-offs between numbers of groups, numbers of individuals, and the extent of the individual and group measurement protocols are discussed in terms of design efficiency. These issues are illustrated in the context of an on-going study of the health effects of air pollution in southern California, in which 12 communities with different levels and types of pollution have been selected and 3500 school children are being enrolled in a ten-year cohort study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Use of an implanted electrode for rehabilitation after tenolysis of the flexor tendons].

The electric stimulation is widely used in flexor tenolysis rehabilitation by the authors. Since 1983 implantable electrodes were used during the operative procedure. Actually they gave better access to the deep muscles (Flexor Profundus of the index), better specificity, less dysesthesia of the skin. Further more they allowed to tests the quality of the tenolysis without wrist incision. This procedure gave 76% of good or very good results over 25 finders in 20 patients. The results were especially good for the index finger which is usually unable to be stimulated by the surface electrodes and for the fingers badly damaged. In this type of situation prognostic was getting better (70% of good and very good results).

Adolescent↗
PubMed1994

Thoracoscopically assisted esophagectomy with gastric pull-up for esophageal cancer.

Thoracoscopically assisted esophagectomy with gastric pull-up was done in a 56-year-old man with esophageal cancer. The thoracoscopic technique, including the use of intraoperative ultrasound, is discussed. The addition of thoracoscopy offers safer and more complete esophageal dissection than transhiatal blunt esophagectomy and is less invasive than conventional thoracotomy.

Adenocarcinoma↗
PubMed1994

[Postinfarction hibernating myocardium].

The detection of hibernating myocardium after infarction is important because it justifies the discussion concerning the revascularisation of infarcted zones irrigated by occluded or severely stenosed vessels, but with an adequate collateral circulation to allow hibernation. The detection of hibernating myocardium is particularly important in patients without the classical indications for revascularisation, such as residual spontaneous ischaemia or ischaemia provoked by exercise or pharmacological stress testing. All techniques currently in use tend to overestimate the size of the necrosed, fibrous scar, compared with the amount of viable myocardium. Improved regional myocardial function after revascularisation is the most convincing proof of hibernating myocardium but it can only be obtained retrospectively. The detection of a reserve of contractility in the necrosed territory by an inotropic stimulus is well adapted to the demonstration of stunned myocardium but this method has not been proved in hibernating myocardium. Thallium scintigraphy is certainly useful in the prospective diagnosis of hibernating myocardium but the protocol of examination should be adapted to this specific problem. There is little available data concerning the evaluation of hibernating myocardium by positron emission tomography: the technical advantages of this method in assessing myocardial viability should enable a more accurate evaluation of post-infarction hibernating myocardium. Adequate revascularisation of necrosed territories depends on a deeper understanding and more precise prospective assessment of postinfarction hibernating myocardium.

Humans↗
PubMed1994

[Pregnancy in patients with heart valve prosthesis. A French retrospective cooperative study (155 cases)].

A French cooperative study of 155 pregnancies in 103 women with valvular prosthesis (95 mechanical, 60 bioprostheses including 27 bivalvular prostheses) is reported. Therefore, a total of 182 prostheses (108 mechanical and 74 bioprostheses) were exposed to the risk of pregnancy. The maternal outcome in the group of 108 mechanical prostheses was complicated by 16 thromboembolic events (TE) including 10 prosthetic valve thromboses which required emergency valve replacement in 4 cases, 6 systemic TE in 13 mitral, 2 aortic and 1 pulmonary mechanical prostheses. The TE were four times more frequent in patients on heparin than in those on oral anticoagulants. There were 4 deaths, 3 among the 10 prosthetic valve thromboses (one reoperation, two sudden deaths). Seven of the 74 bioprostheses were reoperated for degeneration on average 5.9 years after the initial operation but there were no deaths or TE. The outcome of pregnancy was 99 children (63%), 49 of which were born to mothers with mechanical prostheses (53%) and 50 to mothers with bioprostheses (80%) (p < 0.001). Seven of the children were born prematurely, all mothers being on anticoagulant therapy. The birth weight was over 400 grams heavier (3 kg versus 2.6 kg) in the bioprosthesis group (p < 0.05). The 20 spontaneous abortions (13%) were more common in patients on anticoagulants (17%) than in those without (2%) (p < 0.02). Congenital defects due to oral anticoagulants were rare (one certain case). There was one case of phocomelia, an abnormality which has never been described in this context. The 36 remaining pregnancies were still deaths (N = 5), abortion due to maternal death (N = 4), maternal complications (N = 8), therapeutic (N = 9) or voluntary abortions (N = 10) (28 mechanical and 8 bioprostheses).(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Spontaneous↗
PubMed1994

[Pre- and postoperative ventricular arrhythmia in mitral valve insufficiency].

In order to assess the prevalence and prognosis of ventricular arrhythmias in patients with surgical mitral regurgitation, a prospective cooperative study was undertaken in 14 French cardiological centres. Seventy-nine patients (45 men, 34 women, average age 62.8 +/- 12.8 years), who underwent mitral valvuloplasty (44 cases) or valve replacement (35 cases), were included. Three 24 hour Holter recordings were performed before, 15 days and 6 months after surgery. Etiology of mitral disease was dystrophic in 49 patients, degenerative in 11, rheumatic in 10, post-endocarditis in 3 and undetermined in 6. Only 5 patients had a left ventricular ejection fraction < or = 45 %. Complex ventricular arrhythmias (Lown > or = 4) were recorded before surgery in 22 patients (28 %), more often in dystrophic disease (17/49 versus 5/30, p = 0.04). No significant correlation was observed between the ventricular arrhythmias and the other preoperative findings, except for a tendency to an inverse correlation between the left ventricular ejection fraction and the Lown grade. Two patients died in the immediate postoperative period (Lown 1); 1 died of a non-cardiac cause at the 2nd month (Lown 4A). The prevalence of complex arrhythmias was unchanged after surgery (34 % on early Holter and 22% on late Holter recordings) with no difference between valvuloplasty and valve replacement. In conclusion, these results indicate that ventricular arrhythmias do not influence the early and 6 month postoperative prognosis in mitral regurgitation with good left ventricular function.

Aged↗
PubMed1994

Case summary: Kevin.

Kevin suffered a severe Reye's encephalopathy at the age of 11 weeks which left him severely brain damaged. Simple partial seizures started in the recovery phase and were controlled by carbamazepine. He went on to develop symptomatic infantile spasms that were controlled by the addition of clonazepam. He became progressively microcephalic and investigations confirmed cortical blindness and left hemiparesis. Subsequent seizure types included absences and troublesome generalized myoclonic seizures. Now almost six, he attends a special school and is well controlled on a regimen of sodium valproate, clonazepam and lamotrigine.

Anticonvulsants↗
PubMed1994

The demographic transition in southern Africa: reviewing the evidence from Botswana and Zimbabwe.

Part, but not all, of the observed decline in the number of children ever born reported in the 1984 CPS and the 1988 DHS in Botswana and Zimbabwe can be attributed to differences in sample composition: women in the 1988 survey appear to be better educated than women of the same cohort in the 1984 survey. Blanc and Rutstein argue that differences in education levels in the pairs of surveys are not significant. However, weighted Kolmogorov-Smirnov statistics, a comparison of average years of schooling, and the proportions of women who complete primary school or attend secondary school all indicate that the differences are, in fact, significant. This is true in both Botswana and Zimbabwe. Blanc and Rutstein also claim that these differences do not account for any of the observed decline in fertility between the surveys of women age 15 to 49. Their methodology follows cohorts of women rather than age-groups and thus cannot possibly address this issue. Furthermore, to interpret their results, response error and respondent education must be uncorrelated: this is a key assumption which is violated by the data. We stand by our conclusions and argue for caution when aggregate statistics from the CPS and the DHS are used to make projections about the course of fertility and population growth in Botswana and Zimbabwe.

Adolescent↗
PubMed1994

[Kidney cancer: fortuitous discovery of a para-uterine mass at the beginning of pregnancy].

The authors relate the case of an incidental detection of a renal cell carcinoma in pregnancy. The tumor appeared as an heterogeneous adnexial mass. Special consideration for the diagnostic evaluation was taken because of pregnancy and a minimal number of CAT scan was performed. A radical nephrectomy was performed at 13 weeks. The patient tolerance, the pregnancy and postdelivery courses were as well as possible. No recurrence of the carcinoma occurred. This cas is discussed in the light of the literature.

Adult↗