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Biomedical subjects

T J Ryan

Publications and source records attributed to T J Ryan.

At least 199 records · Page 11Linked to original sources
PubMed1991

Time-related changes in lymphatic clearance in pig skin after a single dose of 18 Gy of X rays.

The early and late effects of X rays on lymphatic microcirculatory function have been investigated in pig skin. Paired estimates of lymph clearance were performed in irradiated and unirradiated sites on the flank skin of anaesthetized Large White pigs at 3, 6, 9, 12, 26, 39, 52, 64 and 78 weeks after a single dose of 18 Gy of X rays. The dermal clearance of 99Tcm-colloid was used to assess lymph flow. The results demonstrated two waves of impaired lymphatic clearance which correlated well with the gross morphological changes observed. The first wave occurred between 6 and 12 weeks after irradiation and corresponded to a period of ischaemia and oedema. The second wave, at 52 weeks, corresponded with dermal thinning and subcutaneous atrophy. X irradiation resulted in an impairment of lymph drainage both within and outside the field of irradiation. Impaired lymphatic drainage probably contributes to the gross and histological changes observed in the skin after X irradiation.

Animals↗
PubMed1991

Disability in dermatology.

To be unwelcome is the greatest disability of all. On the other hand, to be confident is a passport for success. Beauty is what people like. If one is ugly one has a significant chance of not being liked and one's chances of achieving one's potential are greatly reduced. Skin failure should rate with heart failure, respiratory failure, liver failure or any other failure as worthy of intensive care.

Dermatology↗
PubMed1990

Biliprotein light-harvesting strategies, phycoerythrin 566.

A series of experiments on the light-harvesting properties of the cryptomonad biliprotein phycoerythrin 566 has been carried out on purified protein isolated from Cryptomonas ovata. Although this pigment has an absorption maximum at 566 nm, a property very close to that of other phycoerythrins, it was found to have a totally unique set of chromophores. The chromophores (bilins) responsible for its absorption spectrum were analyzed by a number of approaches. Chromophore-containing peptides were produced by trypsin treatment and purified in order to isolate the individual peptide-bound bilins free of overlapping absorption. These chromopeptides, after comparison with appropriate controls, showed that three spectrally distinct bilins occurred on the purified oligomeric protein. Two of the bilins were the well-known phycoerythrobilin and cryptoviolin, but the third was previously undiscovered and had an absorption spectrum between that of cryptoviolin and phycocyanobilin. Since the spectral diversity of the three bilins was fully maintained in solvents that minimize the effects of apoprotein on the spectra of the bilins, it is likely that the three bilins are also structurally dissimilar. The alpha and beta subunits, which constitute the protein, were separated by ion-exchange chromatography, and the new bilin was found to be the sole chromophore on the alpha subunit. It was also found that at least two alpha subunits could be separated and they both had this unusual bilin (cryptobilin 596). The beta subunit, therefore, contained both phycoerythrobilin and cryptoviolin. On the basis of the spectra of the three chromopeptides, the absorption spectrum of the protein was modeled using the known absorptivities of cryptoviolin and phycoerythrobilin.

Animals↗
PubMed1990

Dynamic arm exercise during cardiac catheterization in the assessment of stenotic valvular disease.

Assessment of hemodynamic responses during some form of exertion or stress during cardiac catheterization is useful among patients suspected of having valvular stenosis who demonstrate normal or borderline valve gradients at rest. Leg raising exercise and drug administration are commonly used for this purpose, but each has inherent limitations. To evaluate the usefulness of dynamic arm raising exercise as a means of altering hemodynamics during cardiac catheterization, 23 such patients were studied. Measurements obtained during arm raising exercise were compared with those at rest. Heart rate rose by 34 +/- 4 beats/min (p less than 0.001), while cardiac output increased by 1.4 +/- 0.2 l/min (p less than 0.001). Stroke volume decreased slightly, although left ventricular filling pressures and pulmonary capillary wedge pressures rose in nearly all subjects. The change in valvular gradients was variable. These data were compared with those obtained in 11 similar patients receiving either dopamine or isoproterenol as an intervention. The changes in heart rate and cardiac output from the resting state were similar between the groups, with fewer side effects occurring during arm exercise. Dynamic arm exercise is a safe and effective maneuver which can be performed during cardiac catheterization in patients undergoing diagnostic evaluation of stenotic valvular disease.

Adult↗
PubMed1990

Physiologic responses to arm ergometry exercise relative to age and gender.

Arm ergometry exercise testing is a valuable alternative method used in the evaluation and management of patients with both cardiac disease and lower limb impairment. The purpose of this study is to provide information concerning the physiologic responses of normal healthy subjects to arm ergometry relative to age and gender, which could serve as a standard for comparison. Eighty healthy subjects (age 22 to 59 years) cycled at 75 to 80 rpm (on a bicycle adapted for arm ergometry) starting at a power output of 10 W, increasing at 10 W/2 min until exhaustion. Sixty subjects were classified on the basis of age into three groups, each with 10 men and 10 women. Men achieved significantly (p less than 0.001) higher power output (95 +/- 25 W) and oxygen consumption (20.7 +/- 3.9 ml/kg per min) than did women (56 +/- 19 W and 15.5 +/- 3.1 ml/kg per min, respectively). The heart rate response to total body oxygen demand during arm ergometry was significantly higher in women than in men (p less than 0.001). These findings were also present when men and women of each age group were analyzed separately. Older subjects reached a significantly (p less than 0.02) lower peak power output than did younger subjects although they reached a similar level of oxygen consumption. Separate regression equations for predicting oxygen consumption at each power output were formulated for men and women and validated in 20 other subjects. Small differences in measured and predicted oxygen consumption at each stage were found. These data provide additional information concerning arm ergometry testing and should prove useful in diagnostic exercise testing and cardiac rehabilitation.

Adult↗
PubMed1990

Coronary Artery Surgery Study (CASS): comparability of 10 year survival in randomized and randomizable patients.

The Coronary Artery Surgery Study (CASS) includes 780 patients with mild or moderate stable angina pectoris or asymptomatic survivors of a myocardial infarction who were randomized to either medical or surgical therapy and 1,319 patients who were eligible for randomization but were not randomized (randomizable patients). There were no substantial aggregate differences observed in any of the survival comparisons after 10 years of follow-up study between the randomized and randomizable patients assigned to the medical (79% versus 80%) or surgical (82% versus 81%) groups or in patient subgroups stratified according to coronary artery disease extent and left ventricular ejection fraction. Cox regression analyses were done with independent variables known to be predictors of survival, including surgical versus medical therapy and randomized versus randomizable group, to test the null hypothesis of a mortality difference between medical versus surgical assignment according to group assignment (randomized versus randomizable). In no case did the initial group category enter as a significant predictor of survival. The results in the randomizable group reinforce those in the randomized group with respect to the medical versus surgical comparison. Two subgroups are identified with a significant surgical advantage: 1) patients with proximal left anterior descending coronary artery stenosis greater than or equal to 70% and an ejection fraction less than 0.50, and 2) patients with three vessel coronary artery disease and an ejection fraction less than 0.50. In both groups, coronary bypass surgery had a statistically significant beneficial effect on survival (p less than 0.05). After a decade of follow-up, the CASS randomizable patients confirm conclusions reached on the basis of the CASS randomized trial.

Angina Pectoris↗
PubMed1990

The measurement of skin lymph flow by isotope clearance--reliability, reproducibility, injection dynamics, and the effect of massage.

The measurement of skin lymph flow was investigated using an isotope clearance technique (ICT). Multiple lymph flow determinations were undertaken in the skin of anaesthetized large white pigs to test for reproducibility, ascertain the most suitable tracer, study the influence of injection dynamics, and observe the effect of massage as a stimulus to lymph flow. Blood clearance of tracer was also investigated. Results demonstrated that lymphatic clearance is a monoexponential function with good reproducibility under controlled laboratory conditions. 99mTc-colloid (TCK17 Cis) compared favorably with 131I-human serum albumin as a tracer and both performed better than colloid gold (198Au). Lymph flow was significantly faster in one pig than in the other. No difference existed between left and right sides or between caudal and rostral sites on each flank, but clearance was significantly slower in thigh than flank skin. Sub-epidermal injections cleared faster and more consistently than either deep or subcutaneous injections. Neither injection volume nor needle tract backflow of tracer influenced results, but local massage significantly enhanced clearance. Escape of 99mTc-colloid by the blood was negligible. These results indicate that skin lymph flow can be reliably measured when conditions are controlled. Extrinsic factors such as massage strongly influence lymph flow. Greater sensitivity in detecting degrees of lymphatic insufficiency may be achieved if a standardized stimulus to lymph flow is administered during isotope clearance measurement.

Animals↗
PubMed1990

Elastic fibre damage induced by low-dose D-penicillamine.

We have studied 23 patients receiving penicillamine for the treatment of rheumatoid arthritis to determine the prevalence of penicillamine-induced elastosis. One female patient had pseudoxanthoma elasticum-like skin changes and bramble-bush elastosis without calcification in the involved skin. Penicillamine elastosis was present in the joint capsule in 62% of eight patients or 64% of II joints examined and was detected in joint capsules after as little as I year of treatment.

Adult↗
PubMed1990

The prevalence and characteristics of congenital pigmented lesions in newborn babies in Oxford.

Melanocytic naevi (MN) are recognised risk factors for malignant melanoma but the epidemiology of MN is poorly understood. Some MN are present at birth and the study of congenital lesions is an important first step toward understanding the development of MN in early life. In this study, the prevalence and characteristics of congenital pigmented lesions were documented in 1012 White caucasian newborn babies at a maternity hospital in Oxford. Only 12 babies (1.2%) were found to have pigmented skin marks and each of these had only one lesion and no other abnormalities. MN were identified with certainty in only five babies (0.5% of the population; 95% CI, 0.06%-0.93%) thus confirming the relatively low prevalence of this lesion. Four of the MN were noted to be 'small' (less than 15 mm diameter) and all five were less than or equal to 20 mm in diameter. In other respects, the MN displayed a diversity of features. Of the other lesions there were two Mongolian blue spots, one melanocytic pustule, one 'probable' MN and three unusual skin marks where the diagnosis was uncertain but considered unlikely to be MN. During the course of the study, examinations were also carried out incidentally on 39 non-White babies. Twenty-two of these were noted to have Mongolian spots (57%) and three had other pigmented lesions (8%).

England↗
PubMed1990

Darier's disease: a focal abnormality of cell adhesion.

Cell adhesion in clinically normal and involved skin in Darier's disease has been investigated using a suction blister technique. We have been unable to detect a subclinical abnormality in cell adhesion which could predispose to the development of acantholytic papules. There may be synthesis of functionally deficient desmosomes, increased breakdown of desmosomes or abnormalities in other adhesion proteins on the surface of the keratinocyte in Darier's disease, but the abnormality in adhesion is focal and restricted to the clinically and histologically abnormal papules.

Acantholysis↗