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Biomedical subjects

T Ryan

Publications and source records attributed to T Ryan.

At least 163 records · Page 9Linked to original sources
PubMed1985

Skin disease and handicap: an analysis of the impact of skin conditions.

This research sought to quantify the handicapping effect of skin conditions in a far more rigorous way than had previously been attempted. One hundred people who had attended a hospital outpatient clinic during a specified period for treatment of their acne, psoriasis or eczema were interviewed in their homes. A comprehensive and structured interview schedule was used and interviewees were encouraged to talk at length about the impact that their skin conditions had had on their lives. Detailed data were collected that show the serious effect that these diseases can have in several domains. The findings record not only the physical discomfort and inconvenience sufferers may meet but also the consequences for their personal and social life and daily functioning. There is evidence from interviewees' employment experiences of limited opportunities, and functional and interpersonal difficulties in the workplace. 64% of people said that their skin disease affected their socio-economic activity. The extent to which sufferers experienced embarrassment, anxiety, a lack of confidence and depression is documented. 40% of people felt that their social life was affected and there was evidence of particular stresses and demands in personal relationships. The social impact of skin disease is discussed.

Acne Vulgaris↗
PubMed1985

An echocardiographic index for separation of right ventricular volume and pressure overload.

Abnormal motion of the interventricular septum has been described as an echocardiographic feature of both right ventricular volume and pressure overload. To determine if two-dimensional echocardiography can separate these two entities and distinguish them from normal, geometry and motion of the interventricular septum in short-axis views of the left ventricle were evaluated in 12 normal subjects and 35 patients undergoing cardiac catheterization. Thirteen of the 35 patients had uncomplicated atrial septal defect with associated right ventricular volume overload, but no elevation in pulmonary artery pressure. The 22 remaining patients had a pulmonary artery systolic pressure greater than 40 mm Hg and, thus, constituted the group with right ventricular pressure overload. An eccentricity index, defined as the ratio of the length of two perpendicular minor-axis diameters, one of which bisected and was perpendicular to the interventricular septum, was obtained at end-systole and end-diastole. In all normal subjects, the eccentricity index at both end-systole and end-diastole was essentially 1.0, as would be expected if the left ventricular cavity was circular in the short-axis view. In patients with right ventricular volume overload, the eccentricity index was approximately 1.0 at end-systole, but was significantly increased at end-diastole (mean eccentricity index = 1.26 +/- 0.12) (p less than 0.001). In patients with right ventricular pressure overload, the eccentricity index was significantly greater than 1.0 at both end-systole and end-diastole (1.44 +/- 0.16 and 1.26 +/- 0.11, respectively) (p less than 0.001). These results suggest that an index of eccentric left ventricular shape which reflects abnormal motion of the interventricular septum can be defined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Bioengineering changes in spastic cerebral palsy groups following cerebellar stimulation.

Quantitative bioengineering tests were performed on 30 spastic cerebral palsy (CP) patients who underwent chronic cerebellar stimulation (CCS) using the fully implantable pulse generator (Neurolith 601, 1.1-1.8 microC/cm2/phase). Using respiratory inductive plethysmography to measure 8 patients with paroxysmal and/or ataxic breathing patterns, 5 were shown to revert to normal with 3 others markedly improved within 5 months of CCS. Compliance testing of the ankle was performed on 4 patients who showed improvement in 9 of the 16 tests performed. Motor performance ability was evaluated with 9 comprehensive tests in 17 patients. Following 1-2 weeks of CCS, 52% showed performance increases greater than 10%, increasing to 62% during the first year.

Cerebellum↗
PubMed1985

Gallbladder filling and response to cholecystokinin are not affected by vagotomy.

We studied the effects of vagotomy on gallbladder (GB) motility in prairie dogs and humans with infusion cholescintigraphy. Twelve male prairie dogs were anesthetized and given an intravenous infusion of 120 microCi of diethyl-HIDA for 150 minutes. Images were acquired every 10 minutes. Then cholecystokinin (CCK)-8, 1.5 micrograms/kg, was given as a bolus, and images were acquired for another 30 minutes. We repeated the studies giving 300 micrograms/kg of atropine 20 minutes before administration of CCK-8. All animals underwent truncal vagotomy, and the studies were repeated 1 and 3 months later. The GB filled in a stepwise fashion; partitioning of bile varied from one 10-minute period to the next and averaged 20% +/- 2%/80% +/- 3% during the 150-minute period. Episodic partial GB emptying (ejection fraction 19% +/- 2%; intervals of 70 +/- 5 minutes) occurred during this phase. GB filling and partitioning of bile were unchanged after vagotomy. GB ejection fraction in response to CCK-8 was 69% +/- 6% in controls, 74% +/- 5% after atropine, 78% +/- 8% 4 weeks after vagotomy, and 66% +/- 6% 3 months after vagotomy. Sixteen human subjects were studied after parietal cell vagotomy (six patients) or truncal vagotomy and drainage (10 patients). GB filling average 2.5% +/- 2% per minute in patients who underwent truncal vagotomy and 3% +/- 1% per minute in patients who underwent parietal cell vagotomy. GB emptying in response to CCK-33 (0.02 U/kg/min) was 74% +/- 7% in patients who underwent truncal vagotomy and 82% +/- 4% in patients who underwent parietal cell vagotomy. Thus neither GB filling nor GB emptying in response to CCK was altered by cholinergic blockade or vagotomy.

Animals↗
PubMed1983

Transcription analyses with heteroduplex trp attenuator templates indicate that the transcript stem and loop structure serves as the termination signal.

DNA sequences that control transcriptional termination by prokaryotic RNA polymerases normally contain an inverted repeat, or self-complementary sequence, about 10 base pairs upstream from the site of RNA chain termination. Point mutations that interrupt this self-complementarity can reduce or eliminate RNA chain termination. We have constructed heteroduplex DNA templates using wild type and mutant attenuators for the Escherichia coli trp operon to probe the relative contributions of the two DNA strands in the termination process. Transcription analyses show that only the sequences in the transcribed DNA strand determine whether or not a heteroduplex terminator can function. This result strongly supports a model in which the formation of a stem and loop structure in the nascent RNA transcript is the signal for transcriptional termination.

DNA, Bacterial↗
PubMed1983

Bacterioplankton in antarctic ocean waters during late austral winter: abundance, frequency of dividing cells, and estimates of production.

Bacterioplankton productivity in Antarctic waters of the eastern South Pacific Ocean and Drake Passage was estimated by direct counts and frequency of dividing cells (FDC). Total bacterioplankton assemblages were enumerated by epifluorescent microscopy. The experimentally determined relationship between in situ FDC and the potential instantaneous growth rate constant (mu) is best described by the regression equation ln mu = 0.081 FDC - 3.73. In the eastern South Pacific Ocean, bacterioplankton abundance (2 x 10 to 3.5 x 10 cells per ml) and FDC (11%) were highest at the Polar Front (Antarctic Convergence). North of the Subantarctic Front, abundance and FDC were between 1 x 10 to 2 x 10 cells per ml and 3 to 5%, respectively, and were vertically homogeneous to a depth of 600 m. In Drake Passage, abundance (10 x 10 cells per ml) and FDC (16%) were highest in waters south of the Polar Front and near the sea ice. Subantarctic waters in Drake Passage contained 4 x 10 cells per ml with 4 to 5% FDC. Instantaneous growth rate constants ranged between 0.029 and 0.088 h. Using estimates of potential mu and measured standing stocks, we estimated productivity to range from 0.62 mug of C per liter . day in the eastern South Pacific Ocean to 17.1 mug of C per liter . day in the Drake Passage near the sea ice.

Journal Article↗
PubMed1982

Reproducibility of coronary arteriographic reading in the coronary artery surgery study (CASS).

Eight hundred seventy arteriograms from the Coronary Artery Surgery Study (CASS) were independently read by readers at two different clinics to evaluate the reproducibility of the interpretation of coronary arteriograms. Among proximal segments, the interpretation of lesions of the left main coronary artery were the least reproducible, P less than .02. When one angiographer reads a stenosis of 50% or more in the left main coronary artery, it is estimated that a second reader will report no lesion 18.6% of the time. In 94.7% of the films, the number of significantly (greater than or equal to 70% stenosis) diseased vessels was the same for both readers (72.1%) or differed by one vessel (22.6%). The reproducibility of interpretation of films of good or acceptable quality or completeness was better than the reproducibility of readings of arteriograms judged to be of poor quality or incomplete studies. The mean absolute difference between readings of the percent stenosis decreased over the time of the patient enrollment, 1975 to 1978. This may have resulted from major collaborative efforts made during the course of the study to improve the quality of angiography and to standardize the reading of the cine films.

Angiography↗
PubMed1982

Physical mapping of hybrid bacteriophage T7/T3 RNA polymerase genes.

The late regions of the T7 and T3 bacteriophage genomes are transcribed by phage-specified RNA polymerases, the products of gene 1. Although these phage transcriptional systems share many characteristics and are obviously related, they have diverged to such an extent that neither of their respective RNA polymerases utilizes the promotor sites of the other phage at an appreciable rate. However, it is possible to construct viable T7/T3 hybrids which have hybrid gene 1 sequences; the resultant hybrid enzymes exhibit altered transcriptional patterns in that they are capable of transcribing both T7 and T3 DNA to various degrees. The aim of this study was to define more closely the region(s) of the gene 1 sequence which encodes the transcriptional selectivity determinant by correlating the genetic constitution of these hybrid gene 1 sequences with their transcriptional properties. The recombinant sites within the gene 1 regions of several T7/T3 hybrids were mapped by using restriction sites as genetic markers. The results indicated that forcing a crossover event within a particular region often results in the inadvertant selection of additional genetic rearrangements. Several of the hybrid gene 1 sequences were found to have resulted from multiple crossover events, even though only one was directly selected for. In some cases the predicted crossovers were not detected; instead, several hybrids contained recombination sites elsewhere in the gene 1 region. These findings suggest that only certain combinations of T7/T3 gene 1 sequences are compatible; it may be that active hybrid T7/T3 gene 1 sequences rarely result from single genetic rearrangements. Taken together, the results of this study suggest that more than one region of the gene 1 sequence is involved in transcriptional selectivity. More specifically, the region from approximately 25 to 59% (from the left of the gene), together with the carboxyl end, appears to play an important role.

Chromosome Mapping↗
PubMed1981

The kinetics of metaphase arrest in human psoriatic epidermis: an examination of optimal experimental conditions for determining the birth rate.

The optimum experimental conditions have been investigated for the measurement of the birth-rate in human psoriatic epidermis using the vinca alkaloids vinblastine and vincristine. The dose response characteristics of the two drugs were assessed over a 2.5 h collection period; although the dose response characteristics differed between the two agents, a dose of 1 microgram injected intradermally was considered to be optimal for both. The linearity of metaphase correction was assessed for both agents, taking biopsies for up to 10 h after injection. It was found that there was a delay period for up to an hour which must be avoided during the analysis to prevent an underestimate of the birth rate. However, linearity was then demonstrated for up to 4 h after injection. Metaphase degeneration was assessed by isolating a cohort of unlabelled cells in the G2 phase and tracing their fate over the next 10 h. It was found that the minimum life of an arrested metaphase was of the order of 4 h, and then metaphases degenerated at the rate of approximately 0.4% per hour. It is recommended that metaphase arrest experiments in psoriatic epidermis be confined to 4 h although, if required, correction factors are available to correct for experiments which are lengthened. Finally it is shown that flux into DNA synthesis exceeds the flux into mitosis by four or five times; several explanations are considered, and it is thought that the most likely explanation involves the death of psoriatic cells in the G2 phase.

DNA↗
PubMed1978

AMg2+ -dependent class of thick filaments and correlated nuclear chromatin condensation in catfish photoreceptors.

Photoreceptor cells of excised catfish retinae show morphological differences when incubated in Ringer's solutions of varying ionic composition. Two striking changes were observed in photoreceptor cells incubated in a high Mg2+ (25 mM) Ringer's: (1) Thick filaments appeared in the cytoplasm of receptor terminals and myoids; (2) A pronounced condensation of nuclear chromatin occurred in certain nuclei in the outer nuclear layer. The filaments occurred in lattices or bundles. The bundles had a diameter of approximately 0.05--0.2 micrometer and had either tapered or frayed ends. They were observed with somewhat higher incidence in tissue incubated in a 25 mM Mg2+ Ringer's with EGTA added to chelate Ca2+. A common basis for the cytoplasmic and nuclear changes may lie in a redistribution of fibrous protiens brought about by the increased Mg2+ concentration.

Actins↗