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Biomedical subjects

L Walton

Publications and source records attributed to L Walton.

72 records · Page 4Linked to original sources
PubMed1984

Diagnosis of deep-vein thrombosis: comparison of clinical evaluation, ultrasound, plethysmography, and venoscan with X-ray venogram.

In 50 patients with suspected deep-vein thrombosis the diagnostic accuracy of standardised clinical examination, doppler ultrasound, impedance plethysmography, and technetium-99m-labelled-fibrinogen scintigraphy (venoscan) was compared with that of X-ray venography. Physical examination was the least accurate method. Impedance plethysmography, venoscan, and ultrasound had accuracies of 65%, 80%, and 82%, respectively. The initial X-ray venogram report had an accuracy of 90% compared with the interpretation of two experienced radiologists. The venoscan was equivocal in 32% of patients, and in the remaining patients the accuracy was 97%. Objective methods of investigation are essential for diagnosing deep-vein thrombosis. Of those tested, the X-ray venogram was the only investigation suitable for definitive diagnosis. The venoscan may have a role as a screening procedure, to be followed by X-ray venography in patients with equivocal venoscan results.

Adolescent↗
PubMed1984

High serum thyroxine-binding globulin--an important cause of hyperthyroxinaemia.

Four patients are described who had a significant elevation of serum thyroxine-binding globulin (TBG). Review of these patients indicated that inappropriate therapy for thyrotoxicosis had been given in three cases. A study of our laboratory records revealed that significant TBG elevation was a relatively common phenomenon which occurred in approximately 0.45% of our hospital population. Patients with this abnormality have serum thyroxine levels which are comparable to those with clinical thyrotoxicosis. Tri-iodothyronine is frequently elevated though less so than in patients with clinical thyrotoxicosis. Measurement of TBG is indicated in all cases of hyperthyroxinaemia in which the clinical features of thyrotoxicosis are doubtful. The TRH test was found to be most useful in evaluating the thyroid status of these patients.

Adult↗
PubMed1983

Cranial volume and occipito-frontal circumference in neonates.

Occipitofrontal head circumference (OFC), using tape, and calibrated scale and cranial volumes, using styrofoam plastic cast, were measured in nine preterm and 13 term infants. Term infants had a mean +/- S.E. gestation of 40 +/- 0.2 wk and a mean +/- S.E. birth weight of 3461 +/- 108 g. Preterm infants had a mean +/- S.E. gestation of 30.5 +/- 1.4 wk and a mean +/- S.E. birth weight of 1596 +/- 211 g. Five sequential measurements were made on term infants and nine such measurements were done on preterm infants at specified time intervals. The values of cranial volume were compared with previously published results in term infants. Brain weight and cranial volumes were also compared in 10 preterm infants and seven term infants who died of non-intracranial pathology. To determine if this method is reproducible, it was tested using 50 paired measurements and was found to be within 3%. There was a significant decrease in cranial volume in term and preterm infants with time. Term infants reached the control value at 64 h of age and preterm infants reached the control value at 160 h of age. Preterm infants showed a significant decrease in OFC but term infants did not. The rate of change was not significantly different in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1983

An objective feature extraction technique applied to the Doppler waveforms from the groin: a prospective study.

A group of 80 patients presenting with lower limb ischaemia were classified according to their arteriographic findings. The maximum frequency envelope from the Doppler waveforms obtained from the common femoral artery were retrospectively analysed using a mathematical feature extraction technique, principal component analysis (PCA). Two of the three coefficients uniquely describing each waveform were plotted and classified according to their arteriographic groupings. The best separating planes were then defined. Twenty-eight new patients were subsequently prospectively assessed using the principal components and separating planes defined in the previous study. The results were compared with the arteriographic findings and showed that PCA represents a significant improvement in diagnostic accuracy when compared with other techniques.

Aorta↗
PubMed1982

Mononuclear-cell infiltration in ovarian cancer. I. Inflammatory-cell infiltrates from tumour and ascites material.

Malignant effusions and tumour tissue obtained at surgery provided material for a study of the prognostic value of the various inflammatory cells in the prognosis of human ovarian cancer. Ascitic fluids predominantly contained inflammatory cells; tumour cells, both singly and in clusters, were a minor component. Tumour cells were usually in excess in dispersed solid material. Some patients had significant proportions of lymphocytes and macrophages in their solid tumour, and these patients invariably responded to therapy. Sedimentation-velocity separation at unit gravity provided tow populations of inflammatory cells. One consisted of mononuclear cells similar in size to those in the patients blood: the other consisted of one or more large macrophage populations, distinct in morphology and enzymatic markers from both blood monocytes and each other. T lymphocytes were enriched in ascites fractions (78%) and in the tumour-derived mononuclear fraction (71%) compared to patient blood (60%). The T-cell subset characterized by ANAE reactivity was markedly depleted in the tumour-infiltrating fraction (17%) compared to patient blood (62%) or patient blood (51%). Esterase-positive monocyte-like cells were more frequent in the tumour-infiltrating fraction (17%) than ascites (7%) or blood (12%). B lymphocytes were infrequent in solid tumours and difficult to assess in ascites. Histiocyte-like macrophages were present in the higher-velocity tumour-cell containing fractions of both solid and ascitic material. The variation in infiltrating cells between patients and between tumour and ascites of the same individual was marked.

Ascitic Fluid↗
PubMed1982

Mononuclear-cell infiltration in ovarian cancer. II. Immune function of tumour and ascites-derived inflammatory cells.

Mononuclear cell fractions were isolated from blood, ascites and solid tumours of patients undergoing surgery for Stages III and IV adenocarcinoma of the ovary, and evaluated for their response in NK, ADCC and PHA assays. Control experiments with the same fraction of normal blood indicated that these responses were not influenced by the enzymes used to isolate the tumour and ascites inflammatory cells. The inflammatory cell fractions isolated from both tumour sites which sedimented in the velocity range of blood mononuclear cells were adequate in number and composition for comparison with similar cells from blood. E RFC values in both ascites and tumour fractions exceeded those of patient blood. However, there was a marked difference in distribution of the T subsets between blood, ascites and tumour, which could cause the variable test results between the different cell sources. PHA responses of patient blood and ascites fractions were about half that of normal blood. Tumour-infiltrating lymphocytes (TIL) were less than 10% as responsive as normal blood. The depressed PHA responses of the TIL were not due to the presence of a suppressor cell population. NK activity of patient blood was less than that of normal blood, but not as much as the ascites of TIL cells. The activity of the ascites-derived lymphocytes was enhanced by treatment with interferon. ADCC activity against both CRBC and SB cells was normal or higher than controls in patient blood, and depressed in the ascites-derived fractions. TIL responded to less than 10% of the patient blood values. The results indicate a lack of response by ascitic and TIL cells in assays dependent on FcR-bearing effector cells and a greater loss of PHA-reactive cells from the tumour than from blood and ascites. These data could result from intratumour inactivation, or a failure of the particular subset to localize either in the ascites or the tumour site.

Adenocarcinoma↗
PubMed1982

Mononuclear-cell infiltration in ovarian cancer. III. Suppressor-cell and ADCC activity of macrophages from ascitic and solid ovarian tumours.

Macrophages have been isolated from ascitic and collagenase-dispersed tumours from patients undergoing surgery for ovarian cancer. Macrophages were present in varying proportions in both sites, though the ration of macrophages to tumour cells was higher in ascites. Marked variation in size (as detected by sedimentation velocity) and cytochemical markers in the macrophages was noted. Highly enriched macrophage fractions were isolated from the ascites and collagenase-dispersed solid tumours by a combination of sedimentation velocity and selective EA RFC or adherence techniques. Suppressor activity in the PHA assay was detected in tumour macrophages (4/10 giving less than 50% inhibition), ascitic macrophages (1/15) and blood monocytes (2/7). Lymphocyte fractions from tumours were unresponsive to PHA and failed to suppress the blood response. Suppressor activity was also present in the purified tumour-cell fraction of 6/14 patients. ADCC activity was tested in a few patients. When the activity was determined against the SB target cells, tumour-derived macrophages were inactive, whereas the ascitic fraction showed low but significant activity which averaged much lower than patients blood values. The ADCC assays carried out with the CRC target cell indicated activity within the range of patient blood values in 4/4 ascites and 2/4 tumour macrophage fractions. Cytotoxicity was also assessed against co-purified autologous tumour cells. Although activity was detected in many of the tests, the results seemed to reflect target cell sensitivity. There appeared to be a correlation between cytotoxicity with test macrophages and normal blood mononuclear cells. The results indicate that the cytochemical heterogeneity and the variation in size between macrophage fractions is associated with a spectrum of activities.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1982

Monitoring of plasmid-encoded, trimethoprim-resistant dihydrofolate reductase genes: detection of a new resistant enzyme.

Using-gene-specific radiolabeled probe DNAs, we analyzed 42 clinical bacterial isolates with high-level trimethoprim (Tp) resistance for the presence of a type I or a type II plasmid-specified dihydrofolate reductase (DHFR) gene. Plasmid DNA from 17 strains harbored a type I DHFR, whereas 11 isolates contained plasmids that harbored a type II DHFR structural gene. The plasmid DNAs from five strains appeared to hybridize with both type I and type II DHFR probe DNAs. In addition, eight isolates had type I resistance determinants integrated into the chromosomes, presumably on transposon 7 (Tn7). Among the strains analyzed in this survey, none of the chromosomally located, Tp-insensitive reductases were of the type II class. Both the plasmid and chromosomal DNAs of one isolate showed no homology with either the type I or type II DHFR probe DNA. The plasmid harbored by this strain encoded a "new" Tp-resistant enzyme that differed significantly, both in molecular weight and with respect to trimethoprim and methotrexate inhibition kinetics, from the previously characterized plasmid-associated dihydrofolate reductases.

Bacteria↗
PubMedDate not supplied

Prospective assessment of the aorto-iliac segment by visual interpretation of frequency analysed Doppler waveforms--a comparison with arteriography.

In a group of 83 patients the prospective Doppler assessment of disease in the aorto-iliac segment, obtained from visual interpretation of the frequency analysed Doppler waveforms, is compared with subsequent arteriographic findings. The Doppler technique proved to be particularly accurate in the severely diseased vessels (sensitivity 87%, specificity 88%) but tended to underestimate the extent of the minimal/moderate disease.

Angiography↗