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Biomedical subjects

A Thomas

Publications and source records attributed to A Thomas.

At least 19 recordsLinked to original sources
PubMed1992

Vero cytotoxin-producing Escherichia coli O 157 in the United Kingdom.

A total of 226 cultures of Vero cytotoxin-producing Escherichia coli O 157 isolated from humans was received by the PHLS Laboratory of Enteric Pathogens during the six month period January to June 1992. A record monthly total of 122 isolates was received in June. Ten phage types (PT) were identified during this period; PT 2 (45%) and PT 49 (21%) predominated. In addition, 27 human sera with antibodies to E. coli O 157 lipopolysaccharide (LPS) were examined from other cases during this period, making a total of 253 cases of infection associated with E. coli O 157.

Bacterial Toxins↗
PubMed1992

Body size perception and body satisfaction in restrained and unrestrained eaters.

In 21 restrained and 20 unrestrained eaters body size perception was measured using the video distortion technique (VDT), the image marking procedure (IMP) and the kinesthetic size estimating apparatus (KSEA). Body satisfaction was assessed by questionnaires (Body Shape Questionnaire, Dieting scale of the Eating Attitudes Test). Restrained eaters showed no systematic over- or underestimation of the body size but less perceptual accuracy (in VDT and KSEA). Furthermore, they were clearly more dissatisfied with their bodies than unrestrained eaters. Both findings were unrelated to each other. In both groups depressive mood or thoughts seemed to be associated with body dissatisfaction but not with body size misperception. Objective body measures (body mass index, body fat content) were not related to either body size perception or body satisfaction. The findings suggest that a perceptual uncertainty in regard to body size (either for visual or for somatosensory aspects) has already developed in restrained eaters, which may constitute a predisposition for more overt forms of body size misperception as found in eating disorder patients.

Behavior Therapy↗
PubMed1992

Percutaneous lung aspiration biopsy: a comparison between two fine needles.

Fine needle lung aspiration biopsy is now a well established method of obtaining tissue for histopathological diagnosis. It is fast, simple and reliable, and has a very low complication rate. We report our experience using two fine needles, the Turner and the EZ-EM Cut-Biopsy needles, comparing their yield and complication rates. We found that both needles had comparable diagnostic yields (65% with the Turner, and 71% with the EZ-EM) and complication rates. We also found that in most cases, aspirates alone were sufficient for diagnosis, and that obtaining tissue cores with larger bore EZ-EM needles did not significantly influence the diagnostic outcome. We conclude that both the Turner and the EZ-EM needles are equally effective and safe in percutaneous lung aspiration biopsy. The least traumatic needle should be used except when the cytological diagnosis is nonspecific inflammatory cells or inadequate, in which case a repeat with a cutting needle is advised to obtain a core of tissue.

Biopsy, Needle↗
PubMed1992

Evaluation of a Salmonella-specific DNA probe by colony hybridization using non-isotopic and isotopic labeling.

A 2.3 kilobase (kb) Salmonella probe, JEO402-1, and two subfragments, F1214 (1.3 kb) and F1217 (0.8 kb), have been evaluated by colony hybridization using pure cultures of Salmonella serovars and non-salmonella bacteria. JEO402-1, and its subfragments, F1214 and F1217, hybridized to all of 156 different Salmonella serovars tested, while there was no reaction to 112 non-salmonella strains belonging to 19 genera and 37 species of Enterobacteriaceae. Together with previously published results, the JEO402-1 probe has now been shown to detect a total of 396 Salmonella strains belonging to 214 serovars of Salmonella subspecies I-VI. A total of 178 non-salmonella strains representing 23 genera and 51 species of Enterobacteriaceae have all tested negative with JEO402-1. The hybridization results obtained using a digoxigenin-labeled probe were similar to those obtained with 35S isotopic labeling when complete colony lysis was ensured.

Bacterial Typing Techniques↗
PubMed1992

Assessment of function, perfusion, metabolism, and histology in hearts preserved with University of Wisconsin solution.

BACKGROUND: University of Wisconsin solution has shown promise for prolonged cardiac preservation. This study compared the effects of 24-hour cold storage and perfusion preservation techniques by assessment of function, perfusion, metabolism, and histological changes. METHODS AND RESULTS: Three groups of rabbit hearts (n = 6 each) were evaluated: 1) control with immediate reperfusion, 2) continuous perfusion preservation, and 3) cold storage. Hearts were reperfused for 30 minutes, and left ventricular systolic pressure (LVSP) was measured by isovolumetric balloon (LVEDP, 20 mm Hg). We used 201Tl to assess perfusion and 14C-acetate to assess metabolism by macroautoradiography. LVSP was similar for controls and hearts preserved with continuous perfusion (134.8 +/- 2.1 versus 112.2 +/- 6.0 mm Hg, respectively). Hearts preserved with cold storage techniques were significantly worse (36.7 +/- 6.0 versus 134.4 +/- 8.2 mm Hg, p < 0.001). Controls showed homogeneous perfusion and metabolism, whereas hearts in the continuous perfusion group showed mild hypoperfusion and histological damage (26.4 +/- 2.7% of left ventricular cross section). Hearts in the cold storage group had 51.7 +/- 1.2% of the left ventricle hypoperfused and damaged. Histology in the control group was normal; in the perfused group, there were only mild changes; and in the cold storage group, there were extensive derangements of cellular architecture. CONCLUSIONS: Continuous perfusion of the heart with 4 degrees C modified University of Wisconsin solution provided function comparable to that of control. Conversely, cold storage showed extremely poor return of function. Autoradiography confirmed mild perfusion and metabolism abnormalities in control and continuous perfusion hearts, whereas there was marked derangement of cellular architecture, perfusion, and metabolism in the cold storage hearts.

Adenosine↗
PubMed1992

A restaurant-associated outbreak of E. coli O157 infection.

An outbreak of haemorrhagic colitis due to Escherichia coli O157 and associated with a restaurant in Lothian, occurred in September 1990. There were 16 symptomatic cases, four of whom (all children) required dialysis. Notable features of the outbreak were the wide range of incubation periods (1-14 days), the occurrence of secondary spread through asymptomatic carriers and the prolonged period (at least seven days) during which the restaurant appears to have been the source of infection. Despite careful investigation, no single source within the restaurant was identified. The implications for public health are discussed.

Adult↗
PubMed1992

Control of oral anticoagulation in patients using long-term internal jugular catheters for haemodialysis access.

Patients using long-term double-lumen silastic jugular catheters for haemodialysis access frequently require oral anticoagulants to maintain patency of the catheter. It may be difficult or impossible to obtain peripheral vein blood samples for PT measurements to regulate the oral anticoagulant dose. Our studies have shown that removal of 3 mls of blood from the catheter limb containing the heparin (to be discarded) followed by 10 mls as a heparin wash-out (to be returned to the patient) allows blood to be taken from the arterial limb of the catheter for PT measurement. The PT measurement obtained from the arterial limb after a 10 ml wash-out is nearly always identical with the PT measurement on blood obtained from a peripheral vein. If the simultaneously measured aPTT is normal the PT is predictably and consistently accurate. If the aPTT is raised due to traces of residual heparin then the PT may be inaccurate and should be repeated. This method is easy and reliable and can be recommended as an aid to regulation of the oral anticoagulant dose.

Anticoagulants↗
PubMed1991

31P spectroscopy of the human prostate gland in vivo using a transrectal probe.

Using a transrectal probe, good quality 31P magnetic resonance spectroscopy of the human prostate was performed safely, consistently, and in a reasonable amount of time (average of 60 min). Initial results indicate that transrectal 31P MRS has the ability to characterize the phosphorylated metabolites of normal, hyperplastic, and malignant prostates. This study demonstrated that malignant prostates are characterized by significantly decreased levels of phosphocreatine (PCr) and increased levels of phosphomonoesters (PME) as compared to healthy prostates.

Adult↗
PubMed1991

The effect of haematocrit on transthoracic electrical impedance and on the calculation of cardiac output by an impedance cardiograph.

The Transthoracic electrical impedance (TEI) was measured using the Bomed NCCOM3 non-invasive cardiac output monitor in 27 patients with polycythemia rubra vera (PCRV) and in a control group of 27 patients with normal haematocrits. The mean haematocrit was 49.4% (SD 2.61) in the patients with PCRV and 42.1% (SD 2.95) in the control group, a difference that was significant (p less than 0.001). The mean TEI was also significantly higher in patients with PCRV than in the control group (p less than 0.05), the respective values being 31.25 (5.48) Ohms and 27.5 (3.31) Ohms. The mean values for cardiac output (CO) and cardiac index (CI) were similar in both groups.

Cardiac Output↗
PubMed1991

Artemisinin (qinghaosu): the role of intracellular hemin in its mechanism of antimalarial action.

Artemisinin (qinghaosu), is a promising new antimalarial drug derived from an ancient Chinese herbal remedy. When [13-14C]artemisinin is added to cultures of Plasmodium falciparum, it is converted into a product with different solubility and chromatographic properties than the parent drug. Artemisinin reacts with hemin in aqueous solution to form an adduct with an apparent molecular weight of 914 which has identical chromatographic, solubility, and electrophoretic behavior to the parasite-derived product. The reaction between artemisinin and hemin, when carried out in the presence of red cell membranes, leads to the oxidation of protein thiols. Malarial parasites are rich in hemin; artemisinin's reactivity toward hemin may explain its selective toxicity to malarial parasites.

Animals↗
PubMed1991

Applications of DNA probes for Vero cytotoxin-producing Escherichia coli.

Vero cytotoxin-producing Escherichia coli (VTEC) are now recognized as important aetiological agents in human disease. The symptoms of VTEC infection range from mild non-bloody diarrhoea to severe conditions such as haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS). Two types of Vero cytotoxin (VT), VT1 and VT2, have been identified. The genes controlling production of VT1 and VT2 are phageencoded in several E. coli strains and DNA probes have been developed from cloned genes derived from these VT phages. Recently, synthetic oligonucleotide probes for VTEC have also been prepared and evaluated. The VT probes have been labelled radioactively and also non-radioactively with digoxigenin and biotin. Present applications of VT probes include detection of VTEC in faecal samples from patients with diarrhoea, HC or HUS and also the examination of different foods for the presence of VTEC. The proportion of VTEC in the faecal flora or foods may be low, often less than 1%. The use of DNA probes allows several hundred colonies from a sample to be examined and by this technique VT genes were detected in 30-40% of faecal specimens from patients with HC or HUS. Use of methods such as the polymerase chain reaction for amplification of the target genes combined with DNA probes should result in an increased sensitivity for the detection of VTEC.

Bacterial Toxins↗
PubMed1991

Non-radioactively labelled polynucleotide and oligonucleotide DNA probes, for selectively detecting Escherichia coli strains producing Vero cytotoxins VT1, VT2 and VT2 variant.

Vero cytotoxin producing Escherichia coli (VTEC) were detected in faecal specimens and bacterial isolates, using non-radioactively labelled polynucleotide and oligonucleotide DNA probes specific for Vero cytotoxin (VT) genes. VT1 and VT2 structural gene sequences, previously cloned and used for radioactive probes, were labelled with digoxigenin or biotin. Oligonucleotide gene sequences coding for the A subunit of VT1, VT2 and VT2 variant were labelled with digoxigenin. The VT1 and VT2 probes were specific for detecting VT1 and VT2 gene sequences and gave very similar results to those obtained using the radioactive label 35S as a standard. The VT2 variant probe hybridized only with the strains of porcine origin. For the range of isolates tested, there was little significant difference in specificity and sensitivity between the digoxigenin-labelled polynucleotide and oligonucleotide probes. The biotin system gave rise to more non-specific effects, particularly with some non-E. coli strains, and was therefore less reliable. All of the digoxigenin-labelled probes gave satisfactory results after several times re-use, which is of importance when considering cost.

Bacterial Toxins↗
PubMed1991

Characterization of prostate cancer, benign prostatic hyperplasia and normal prostates using transrectal 31phosphorus magnetic resonance spectroscopy: a preliminary report.

We assessed the ability of 31phosphorus (31P) transrectal magnetic resonance spectroscopy to characterize normal human prostates as well as prostates with benign and malignant neoplasms. With a transrectal probe that we devised for surface coil spectroscopy we studied 15 individuals with normal (5), benign hyperplastic (4) and malignant (6) prostates. Digital rectal examination, transrectal ultrasonography and magnetic resonance imaging were used to aid in accurate positioning of the transrectal probe against the region of interest within the prostate. The major findings of the in vivo studies were that normal prostates had phosphocreatine-to-adenosine triphosphate (ATP) ratios of 1.2 +/- 0.2, phosphomonoester-to-beta-ATP ratios of 1.1 +/- 0.1 and phosphomonoester-to-phosphocreatine ratios of 0.9 +/- 0.1. Malignant prostates had phosphocreatine-to-beta-ATP ratios that were lower (0.7 +/- 0.1) than those of normal prostates (p less than 0.02) or prostates with benign hyperplasia (1.1 +/- 0.2, p less than 0.01). Malignant prostates had phosphomonoester-to-beta-ATP ratios (1.8 +/- 0.2) that were higher than that of normal prostates (p less than 0.02). Using the phosphomonoester-to-phosphocreatine ratio, it was possible to differentiate metabolically malignant (2.7 +/- 0.3) from normal prostates (p less than 0.001), with no overlap of individual ratios. The mean phosphomonoester-to-phosphocreatine ratio (1.5 +/- 0.5) of prostates with benign hyperplasia was midway between the normal and malignant ratios, and there was overlap between individual phosphomonoester-to-phosphocreatine ratios of benign prostatic hyperplasia glands with that of normal and malignant glands. To verify the in vivo results, we performed high resolution magnetic resonance spectroscopy on perchloric acid extracts of benign prostatic hyperplasia tissue obtained at operation and on a human prostatic cancer cell line DU145. The extract results confirmed the differences in metabolite ratios observed in vivo. We conclude that transrectal 31P magnetic resonance spectroscopy can characterize metabolic differences between the normal and malignant prostate.

Adult↗