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Biomedical subjects

T Davies

Publications and source records attributed to T Davies.

At least 19 recordsLinked to original sources
PubMed1995

Quantitative endoluminal measurements during angioscopy: an innovative technique.

AIM: To evaluate angioscopy in this Unit with respect to its application in lower limb vascular reconstructions. By providing magnified, colour images of the luminal surfaces of vein grafts, anastomoses and native arteries, angioscopy allows direct visualisation of imperfections and is sensitive in diagnosing technical problems. However, assessment is qualitative and magnification of the image can distort the operator's impression of true size. Angioscopy would be more versatile if it were possible to quantify the observed images. METHOD: A new technique has been developed to measure intra-luminal diameter from the angioscopic images. A linear displacement transducer is attached to the angioscope and accurately monitors its axial shift. Signals from the transducer are received by a personal computer equipped with a video frame grabber and analogue digital converter, together with appropriate software. The computer generates calculated dimensions based on geometrical principles, once each angioscope has been appropriately calibrated at the outset. RESULTS: Laboratory studies examining tubes of known dimensions have confirmed the reproducibility and accuracy of the technique. Simultaneous angioscopic and Duplex ultrasound measurements of the internal diameters of segments of vein suspended in a water bath were then carried out. Using the Duplex results as the 'gold standard', there was a strong correlation between the measurements obtained with the two techniques (Rs = 0.92). CONCLUSIONS: In the clinical context, this system has the capability to generate accurate endoluminal measurements during angioscopy. This has application for quality control in the selection of veins and inspection of run-off vessels during bypass grafting and in completion studies, following both operative and percutaneous procedures.

Analog-Digital Conversion↗
PubMed1995

Urinary excretion of cortisol after immunisation.

Urinary cortisol excretion and rectal temperature were measured in 66 infants before and after immunisation against diphtheria, tetanus, pertussis, and Haemophilus influenzae type b. Immunisation produced a significant increase of rectal temperature the next night at all ages. Infants without an adult-like night time body temperature pattern had a significant increase in urinary cortisol excretion night and morning after immunisation. Once an adult-like night time body temperature pattern developed immunisation no longer significantly raised urinary cortisol output.

Age Factors↗
PubMed1994

Diagnosis of Bloom's syndrome by sister chromatid exchange evaluation in chorionic villus cultures.

Cultures of a chorion biopsy taken from a pregnancy at risk of Bloom's syndrome revealed the high sister chromatid exchange frequency diagnostic of this rare disorder. To obtain the result, cultures were grown under standard conditions, with the addition of 10 microM 5'-bromodeoxyuridine for the final 48 h of incubation. This result demonstrates the feasibility of early prenatal diagnosis of Bloom's syndrome.

Bloom Syndrome↗
PubMed1993

Staging of gastrulating mouse embryos by morphological landmarks in the dissecting microscope.

We describe and illustrate a set of morphological landmarks for classifying mouse embryos by gross morphology from before gastrulation to the beginning of organogenesis. These landmarks are visible at the resolution of the dissecting microscope in embryos that are intact except for reflexion of Reichert's membrane. Adoption of these criteria should facilitate interpretation of both the expression patterns of genes and the consequences of experimental manipulation of embryos during early postimplantation development.

Animals↗
PubMed1992

The Hough transform for locating cell nuclei.

A method of cytologic image segmentation that works purely on the basis of geometric information is described. Cell nuclei are assumed to be circular or elliptical. The latest ellipse-finding Hough transform is then used to locate the nuclei. The results are encouraging.

Cell Nucleus↗
PubMed1991

Computerisation of primary care in Wales.

OBJECTIVE: To obtain information about the computerisation of general practice in Wales, and to enable more effective planning of educational provision for doctors and other primary health care workers. DESIGN: Postal questionnaire sent to all general practices in Wales. SUBJECTS: 553 general practices, of which 401 (73% replied). RESULTS: The level of computerisation varied from 11 (85%) of practices in Powys Family Health Services Authority to 22 (40%) in Mid Glamorgan. Less than half of practices had a computer in only two authorities. The commonest uses of the computer were for patient registration (208 practices), repeat prescribing (180), call and recall of patients (165), and partial clinical records (122). The main suppliers were VAMP (78 practices), AAH Meditel (46), and AMC (23). 102 of 226 practices with a computer had a terminal on each doctor's desk. Just 33 practices had full patient notes on computer and 51 had modems for electronic communication. CONCLUSION: Mechanisms to encourage greater and more sophisticated use of computers and information technology need to be explored.

Ambulatory Care Information Systems↗
PubMed1991

Oral poliovirus vaccine in the United States: molecular characterization of Sabin type 3 after replication in the gut of vaccinees.

Derivatives of Sabin 3 shed from recipients of oral poliovirus vaccine in the United States (U.S.) were examined for genetic changes identified in strains excreted by vaccinees in the United Kingdom [U.K.; Evans et al., 1985; Cammack et al., 1988, Macadam et al., 1989]. Among the eight primary vaccinees studied, the duration of excretion and molecular evolution of type 3 strains varied greatly. The period of virus excretion after vaccination ranged from as few as 2 days to as many as 36 days. Nucleotide sequence analysis of viral RNAs extracted from shed virus indicated that only fifty percent of the vaccinees exclusively excreted strains in which the attenuating mutation at nucleotide 472 in the 5' noncoding region of the genome had reverted from uracil (U) to cytosine (C), the nucleotide found in neurovirulent strains. Compared to the wild-type Leon strain, the low activity of stool isolate KW4 in a complete monkey neurovirulence test demonstrated that presence of C at 472 does not render a type 3 strain pathogenic. Conversely, an isolate was identified which efficiently replicated in monkey nervous tissue and maintained the attenuated U at 472. Oligonucleotide fingerprinting and sequence analysis of viral RNAs from stool isolates indicated that one vaccinee (KW) eventually excreted intertypic recombinant strains consistent with those reported in the U.K. studies. Unique to this study, one vaccinee (KS) excreted nonrecombinant virus possessing U at 472 for up to 21 days. The significance of the KS strain profile in relation to differences in the U.S. vaccine compared to the vaccine distributed in the U.K. and other countries is discussed.

Animals↗
PubMed1988

Peroxisomes in pigment epithelium and Müller cells of amphibian retina possess D-amino acid oxidase as well as catalase.

In this paper we identify peroxisomes in Müller cells and retinal pigment epithelial cells of Rana pipiens and Xenopus laevis by virtue of their content of cytochemically stainable catalase. These organelles have the form of an extensive, branched system of tubules in the retinal pigment epithelium and appear as discrete ovoid structures in the Müller cells. In both the pigment epithelium and the Müller cells a second peroxisomal enzyme, D-amino acid oxidase, can be detected in the same structures as catalase by means of a cerium-based cytochemical staining procedure. This oxidase is active only against nonpolar and polar, uncharged D-amino acids.

Animals↗
PubMed1988

Nuclear medicine studies of aging--III. Radial bone mineral content by single and dual photon absorptiometry.

Measurement of bone mineral content of the radius has been possible by single photon absorptiometry. Recently, dual photon devices have become widely used for measuring the quantity of lumbar vertebral bone mineral. Therefore, we studied the utility of a dual beam machine for quantifying the bone mineral content of the radius, and compared results with those obtained by single photon absorptiometry in the same patient on the same day. There was an excellent correlation between single and dual beam measurements of the radius. The present study indicates that a dual photon machine can be used for assessing not only vertebral, but radial bone mineral content as well. This may facilitate studies of the two sites by use of one machine.

Adolescent↗