Search PubMed⌕ Search

Biomedical subjects

P Ward

Publications and source records attributed to P Ward.

At least 145 records · Page 8Linked to original sources
PubMed1987

MR imaging of the intratemporal facial nerve by using surface coils.

MR images of the intratemporal portion of the facial nerve were obtained with surface coils using a 0.3-T permanent magnet whole-body imaging system. Various 2DFT spin-echo pulse sequences were used to produce 5-mm thick sections with 0.5-mm pixels on a 512 X 512 acquisition matrix. The MR images from normal volunteers were correlated with cryosection specimens of three fresh human cadavers. The seventh nerve was followed in the internal auditory and fallopian canal and through temporal bone to the stylomastoid foramen. The entire labyrinthine, tympanic, and mastoid portions, as well as the geniculate ganglion, could be shown with appropriate scan planes. MR produces excellent images of the facial nerve with high-contrast resolution. Unlike CT, no beam-hardening artifact from the temporal bone is apparent. MR should be a sensitive study for the evaluation of intratemporal facial nerve disease.

Facial Nerve↗
PubMed1986

Conversion of kinins and their antagonists into B1 receptor activators and blockers in isolated vessels.

A carboxypeptidase inhibitor (DL-2-mercaptomethyl-3-guanidoethylthiopropranoic acid) (mergetpa) was used to block the conversion of kinins and B2 receptor antagonists into metabolites devoid of the C-terminal Arg. Experiments were carried out on rabbit isolated aortae (a B1 receptor system) or rabbit jugular veins and dog carotid arteries (two B2 receptor systems). The contractile effect of bradykinin in the rabbit aorta was significantly reduced by mergetpa while that of desArg9-BK was not modified. pA2 values of B2 receptor antagonists, [Thi5,8,D-Phe7]bradykinin and [Thi6,9,D-Phe8]kallidin were markedly reduced by mergetpa. The apparent affinity (pA2) of a B1 receptor antagonist, [Leu9]desArg10-kallidin was not affected. Carboxypeptidases inhibition did not modify the activities of bradykinin or the affinities of B2 receptor antagonists in the rabbit jugular vein and the dog carotid artery. An inhibitor of kininase II (D-3-mercapto-2-methylpropranoyl-L-proline (S,S] (captopril) reduced the contractile effects of angiotensin I in the three preparations and potentiated the stimulatory or inhibitory effects of bradykinin: captopril did not have effect on the affinities of B2 receptor antagonists and did not modify the effects of angiotensin II. Comparative experiments performed in tissues with or without endothelium gave the same results with both mergetpa and captopril. The present findings suggest that bradykinin and B2 receptor antagonists are converted by carboxypeptidases into biologically active B1 receptor agonist or antagonists. This is the reason why B2 receptor antagonists are not selective.

3-Mercaptopropionic Acid↗
PubMed1986

Antibiotic-associated colitis caused by Clostridium difficile: relapse and risk factors.

Relapse is a common sequel of antibiotic-associated colitis due to Clostridium difficile. It has been suggested that Cl. difficile may persist in the stools in spite of the resolution of symptoms after treatment and this may cause the relapse. Our study was designed to define the factors that predispose to relapse and to determine if prolonging treatment to clear Cl. difficile from the stools might prevent relapse. Of 60 consecutive patients, 36 with more severe disease required treatment. Treatment with either vancomycin or bacitracin was continued until the results of the examination of stools for cytotoxin became negative and Cl. difficile could no longer be cultured (sensitivity of culture was 10-100 organisms/mL). This was achieved in 35 patients who were then followed for one month. Symptoms reappeared in 10 (28.6%) of the treated patients while Cl. difficile reappeared in the stools of an additional seven patients (20%) without the recurrence of diarrhoea. On comparing those who relapsed with those who did not, the age (67.3 +/- 5.5 years in those who relapsed compared with 51.6 +/- 4.4 years; P less than 0.025, means +/- SE) and a history of recent abdominal surgery (59% of those who relapsed compared with 17%; P less than 0.05) were significantly different. Although those who relapsed had received therapy with multiple antibiotic agents more often, this was not statistically significant. Disease was not more severe in patients who relapsed, nor was it more difficult to clear the pathogen from these patients. The 24 untreated patients did not suffer symptomatic relapse. Continuation of treatment until Cl. difficile apparently is absent from the stools is expensive and does not prevent relapse. Elderly patients and those who have recently undergone abdominal surgery are more likely to suffer a relapse.

Aged↗
PubMed1986

Natural populations of Trypanosoma cruzi, the agent of Chagas disease, have a complex multiclonal structure.

We have studied 15 gene loci coding for enzymes in 121 Trypanosoma cruzi stocks from a wide geographic range--from the United States and Mexico to Chile and southern Brazil. T. cruzi is diploid but reproduction is basically clonal, with very little if any sexuality remaining at present. We have identified 43 different clones by their genetic composition; the same genetic clone is often found in very distant places and in diverse hosts. There is much genetic heterogeneity among the different clones, and they cannot be readily classified into a few discrete groups that might represent natural taxa. These findings imply that the biological and medical characteristics need to be ascertained separately for each natural clone. The evidence indicates that clonal evolution is very ancient in T. cruzi. We propose two alternative hypotheses concerning the relationship between the biochemical diversity and the heterogeneity in other biological and medical characteristics of T. cruzi. One hypothesis is that the degree of diversity between strains simply reflects the time elapsed since their last common ancestor. The second hypothesis is that biological and medical heterogeneity is recent and reflects adaptation to different transmission cycles. A decision between the two hypotheses can be reached with appropriate studies, with important medical consequences.

Alleles↗
PubMed1986

Magnetic resonance imaging of the facial nerve. Normal anatomy and pathology.

Magnetic resonance imaging with surface coils permits visualization of the facial nerve from within the brainstem and continuing through a major portion of the parotid gland. Diagnostic capabilities have been expanded to include white matter disease that affects the tracts of the facial nerve within the brainstem and tumors of the parotid gland that involve the facial nerve trunks after the nerve exists from the stylomastoid foramen.

Facial Nerve↗
PubMed1986

Drug delivery to tumors. A problem requiring microscopic resolution.

One factor in the effectiveness of chemotherapy for both primary tumors and their metastases is the delivery of the drug to the cancer cells within the tumor. The uptake of Adriamycin, assayed in 8 cu mm samples from primary tumors, lung metastases and "normal" lung tissue (unaffected by the metastases) in mice, showed wide variations between different tumors, between primary tumors and their metastases and between different metastases. The heterogeneity of uptake was greater in tumors than in normal lung tissues, whose uptake was in the range of the metastases, i.e., higher than in the tumor itself. Studies of Adriamycin uptake within individual tumors showed a wide range of values; this variability was statistically significantly increased as compared with the variation in normal lung tissues. Since the lower levels found in some tumor areas were below the cytotoxic level, those areas may represent "drug-resistant" cells from which tumor recurrence could ensue. In a three-dimensional reconstruction, the areas of lowest uptake were found at both peripheral and internal regions, a finding not in accord with the concentric zonal concentration expected on the basis of considerations of tumor vascularity. It is suggested that the problem of drug delivery to tumors needs further study at the microscopic level and that automated microscopic image analysis and three-dimensional reconstructions of serial sections could greatly extend the macroscopic findings of this study.

Animals↗
PubMed1985

Physicochemical properties of a beta-lactamase from Streptomyces UCSM-104.

A purified beta-lactamase from Streptomyces UCSM-104 shows the presence of three subforms when stained for protein and/or for activity after polyacrylamide gel electrophoresis or after electrofocusing. The pI values of the three subforms were 5.45, 5.30 and 5.10, respectively. The respective electrophoretic mobilities were 4.6 X 10(-5), 5.2 X 10(-5) and 5.9 X 10(-5)m2/sV. Relative molecular mass of 14,900 was determined. The amino acid composition was established. Cysteine was not detected. A fairly high proline content (8.3%) differentiates this enzyme from other beta-lactamases. Lysine was the only N-terminal amino acid detected after dansylation. The possible origin of the subforms is discussed.

Amino Acids↗
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

Psychological aspects of genetic counseling. III. Management of guilt and shame.

Reactions of guilt and shame are conspicuous in the context of genetic counseling, and the relief of their distressing aspects is a widely held goal of genetic counselors. They are in a unique position to accomplish this; however, guidelines as to how one might proceed are not readily available. We have considered guilt and shame responses and have attempted to differentiate them, dynamically and developmentally, and have pointed out how each might be manifested in the course of genetic counseling. The major counseling tactics by means of which the alleviation or reduction of feelings of guilt and shame might be achieved are outlined and case illustrations are provided in which actual and potential counseling situations are explored and discussed.

Adult↗
PubMed1984

Location of the retinoblastoma susceptibility gene(s) and the human esterase D locus.

Retinoblastoma occurs with increased frequency in children born with a deletion of the long arm of chromosome 13. Recent reviews have noted that the region 13q14 is consistently deleted in documented cases. Prometaphase and late prophase banding allowed Yunis and Ramsay to determine that a deletion in one patient included the sub-bands q14 . 12, q14 . 13, and q14 . 2, and a portion of q14 . 11 and q14 . 3. We report the results of similar cytogenetic techniques applied in the case of a 26 month old Caucasian female with unilateral retinoblastoma, moderate developmental delay, and subtle dysmorphology. Prometaphase banding of cultured skin fibroblasts revealed the karyotype: mos46,XX/46,XX,del(13)(q13 . 1q14 . 11). Only the sub-band q14 . 11 is deleted in both our patient and that of Yunis and Ramsay. The results are consistent with the localisation of the retinoblastoma susceptibility gene(s) in the sub-band 13q14 . 11. Electrophoretic analysis and activity assays of red blood cell esterase D are consistent with hemizygous expression of that marker in our proband. Comparison with published esterase D analyses in families with retinoblastoma permits the assignment of the esterase D locus to that same sub-band, 13q14 . 11.

Carboxylesterase↗
PubMed1983

The measurement of antithyroglobulin autoantibodies in the presence of thyroglobulin.

An homogeneous phase radioassay (HRA) for antithyroglobulin autoantibodies (TgAb) in serum was investigated. In this method TgAb is allowed to react with 125I-Tg in solution and the immune complexes formed are separated by precipitation with sheep anti-human gammaglobulin. HRA proved to be suitable for the screening of sera prior to thyroglobulin (Tg) radioimmunoassay; being both sensitive, and unaffected by high endogenous levels of Tg. HRA was more sensitive than either of two commercial TgAb kits; a hemagglutination assay (Wellcome Australia Ltd.) and a solid phase radioassay (CIS France). Positive responses were obtained with 4 out of 42 normal subjects (titers up to 1/10), 24 out of 31 with untreated Graves' disease (titers up to 1/10,000) and all out of 18 with Hashimoto's thyroiditis (titers up to 1/10,000). Binding of 125I-Tg was displaceable with added unlabelled Tg, but in no case could it be abolished with less than 1,000 micrograms/l. Some sera exhibited more than one class of binding site and variation in both affinity and capacity for Tg was observed. It was concluded that the use of an assay standard for the reporting of results in units of concentration is invalid, although units of TgAb activity may be used as long as the analytical method is specified. Serum levels of TgAb may also be reported in semi-quantitative terms, such as in this report where a binding titer is used, or alternatively, antigen binding capacity may be reported.

Autoantibodies↗