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Biomedical subjects

T J Ryan

Publications and source records attributed to T J Ryan.

At least 253 records · Page 14Linked to original sources
PubMed1987

Time to first new myocardial infarction in patients with mild angina and three-vessel disease comparing medicine and early surgery: a CASS registry study of survival. Coronary Artery Surgery Study.

Two categories--patients alive and free from new myocardial infarction (MI) and time to first new MI (nonfatal and fatal)--were compared in medical and early surgical groups in the Coronary Artery Surgery Study (CASS) registry with Class I or II angina and three-vessel disease in a six-year follow-up. There were 413 in the medical group and 443 in the early surgical group. A broad definition of MI using ECG and clinical criteria on hospital discharge and follow-up was used to include as many new MIs as possible, including perioperative MIs. Stratification was by left ventricular wall motion score and number of proximal segment stenoses and by quintile of propensity score to reduce selection bias in therapy groups. Adjusted by propensity analysis, 79% of medical and 88% of surgical patients (p = .005) were free from new MI; death without diagnosis of new MI was censored. Similarly adjusted, 57% of medical and 76% of surgical patients (p less than .0001) were alive and free from new MI at six years. For patients with previous MI, surgery offered the probability of protection from new MI: with multiple prior MIs, 66% of medical and 88% of surgical patients were free from new MI at six years (p = .0019). This is a nonrandomized, observational study with the limitations of such studies: the need to adjust for differences in baseline traits in medical and surgical groups and the unknown effects of unobserved variables. Fifty-one variables, including therapy, were tested by Cox model with time to new MI as the end point. Early surgery was the strongest independent predictor of freedom from new MI (p = .002) with a relative risk of 51% compared with medical therapy (95% confidence limits of 33 to 78%). In patients with multiple prior MIs, the new MI risk with early surgery was 24% of that for medicine, with an upper 95% confidence point of 64%.

Angina Pectoris↗
PubMed1987

Medical versus early surgical therapy in patients with triple-vessel disease and mild angina pectoris: a CASS registry study of survival.

Results of coronary artery bypass grafting were evaluated in 856 nonrandomized patients in the Coronary Artery Surgery Study (CASS) registry with mild angina (Canadian Cardiovascular Society Classes I and II) and three-vessel disease, defined as 70% or more stenosis in the proximal or middle segment of the three major coronary arteries. There were 413 patients with medical therapy and 443 with early operation. Patients with delayed operation were kept in the medical group for analysis. Six-year survival adjusted for left ventricular (LV) function and number of proximal stenoses was 67% for medical and 84% for surgical patients (p less than 0.0001). Patients with normal LV function had equal survival with medicine or surgical intervention. Those with mild or moderate LV dysfunction (CASS LV wall motion score 6 to 9 and 10 to 15, respectively) and at least one proximal stenosis (the dominant right coronary artery) had increased probability of being alive at six years with surgical treatment. In patients with severe LV impairment (LV score higher than 15) and in those whose only proximal stenosis of 70% or more (in three-vessel disease) was located in the left anterior descending coronary artery, increased survival with surgical treatment could not be demonstrated. This is a nonrandomized observational study with the limitations of such studies: the need to adjust for differences in baseline traits between medical and surgical groups and the possibility of an unrecognized imbalance in baseline characteristics. In a Cox analysis of variables influencing outcome, early surgical treatment was an independent predictor of survival with 43% the risk of medical treatment (95% confidence range: 29 to 62%). Adjustment by propensity analysis to reduce selection bias from known differences in baseline variables did not alter results.

Angina Pectoris↗
PubMed1987

Arm exercise-thallium imaging testing for the detection of coronary artery disease.

Patients with lower limb impairment are often unable to undergo a standard bicycle or treadmill test for the evaluation of coronary artery disease. To establish an alternative method of testing, 50 subjects (aged 56 +/- 10 years) performed arm ergometry testing in conjunction with myocardial thallium scintigraphy. All underwent coronary angiography; significant coronary artery disease (greater than or equal to 70% stenosis) in at least one vessel was present in 41 (82%) of the 50 patients. Thallium scintigraphy was found to have an 83% sensitivity and 78% specificity for detecting coronary disease, compared with a sensitivity and specificity of 54% (p less than 0.01) and 67% (p = NS), respectively, for exercise electrocardiography. In the subgroup of 23 patients who had no prior myocardial infarction or left bundle branch block and were not taking digitalis, thallium scintigraphy had a sensitivity of 80% versus 50% for exercise electrocardiography. Scintigraphy yielded a sensitivity of 84, 74 and 90% for one, two and three vessel disease, respectively. Noninvasive arm ergometry exercise-thallium imaging testing appears to be reliable and useful and should be considered in the evaluation of coronary artery disease in patients with lower limb impairment.

Adult↗
PubMed1987

Tattoo removal using infra-red coagulation: a dose comparison.

Using an infra-red coagulator, 42 tattoos were treated using pulses of 1.125 s (27 tattoos) or 1.25 s (15 tattoos). Treatment failures occurred only in three professional tattoos. Amateur tattoos were satisfactorily treated in over 80% of cases regardless of dose. Deeper collagen necrosis occurred with 1.25 s, but scarring was clinically similar. Pre-treatment biopsy to assess pigment depth was of no value in selection of the optimum pulse duration and increased the complication rate. The possible mechanism of pigment removal is discussed.

Dermatologic Surgical Procedures↗
PubMed1987

An investigation of the angry back syndrome using Trafuril.

The angry back syndrome (ABS) was investigated using Trafuril cream and prostaglandin synthetase inhibitors. Trafuril produced an increase in the numbers and intensity of patch test reactions which was partly abrogated by aspirin and indomethacin. Irritant reactions were not affected. We suggest that Trafuril may increase the sensitivity of the patch testing system and that this may have useful clinical applications.

Aspirin↗
PubMed1987

Inhibition of fibrinolytic system by liquoid (polyanetholesulfonate). A contributing factor in the liquoid-induced renal cortical necrosis.

Liquoid induces microvascular thrombosis and renal cortical necrosis in experimental animals. We hypothesized that thrombosis and renal cortical necrosis may, at least in part, result from the inhibition of the fibrinolytic system by liquoid. Effects of liquoid on plasminogen activation by rat kidney, purified human tissue plasminogen activator (TPA), urokinase, streptokinase, and on the amidolytic activities of TPA, urokinase, and plasmin were studied using chromogenic substrates and clot lysis. Liquoid had a strong inhibitory effect on the fibrinolytic system in vivo and in vitro. The inhibition was most effective at the plasminogen activation level, with activation by streptokinase being most susceptible. The demonstrated stoichiometric binding between liquoid and plasminogen, and to a lesser degree the direct inactivation of plasminogen activators and plasmin, is probably responsible for the reduction of plasminogen activation in circulation and in the kidneys.

Animals↗
PubMed1987

Platelet accumulation in experimental angioplasty: time course and relation to vascular injury.

Since platelet accumulation may be an important determinant of restenosis after angioplasty, the time course of 51Cr-labeled platelet accumulation after experimental angioplasty was evaluated in a deendothelialized, hypercholesterolemic rabbit preparation of atherosclerosis. Marked platelet accumulation (39.5 +/- 8.7 X 10(6) platelets/1 cm vessel length) was observed at 30 min and remained active until 4 hr after angioplasty. Total accumulation over 24 hr was 56.4 +/- 4.7 X 10(6) platelets/1 cm length. Histologic dissection was directly related to the degree of platelet accumulation, with 64 +/- 15 X 10(6) platelets/1 cm in the group with marked dissection and 8.7 +/- 3.7 X 10(6) platelets/1 cm in the group with minimal dissection (p less than .05). Increasing angiographic dissection also resulted in a trend toward increased platelet accumulation, and angiographic change in luminal diameter showed a significant correlation with platelet accumulation. It is concluded that marked platelet accumulation occurs early after transluminal angioplasty and is related to the extent of dissection. Restenosis may result from a complex interaction of platelet accumulation, vascular damage, and blood flow.

Angioplasty, Balloon↗
PubMed1987

Angiographic and histologic consequences of laser thermal angioplasty: comparison with balloon angioplasty.

The angiographic and histologic consequences of laser thermal angioplasty were examined and compared with those of conventional balloon angioplasty in an atherosclerotic rabbit iliac artery preparation immediately and 4 weeks after the procedure. Nineteen vessels in 13 rabbits underwent either laser thermal or balloon angioplasty in random order. Laser thermal angioplasty was performed in a total of nine vessels with either a 1.5 or 2.0 mm laser-heated metallic-capped fiber by delivery of 6 or 8 W, respectively, of argon laser energy for 5 sec duration during continuous advancement through the stenosis. Balloon angioplasty was performed in a total of 10 stenotic lesions with a 2.5 mm balloon catheter. The immediate enlargement of the angiographic luminal diameters was similar for both procedures: from 1.0 +/- 0.2 to 1.9 +/- 0.2 mm for laser thermal angioplasty vs 1.0 +/- 0.1 to 2.0 +/- 0.2 mm for balloon angioplasty. However, 4 weeks later the vessels treated with laser thermal angioplasty had less restenosis, defined as a 20% or greater reduction in luminal diameter (two of nine vessels [22%] vs 10 of 10 vessels [100%]; p less than .001), and a significantly larger mean luminal diameter (1.6 +/- 0.5 vs 1.0 +/- 0.4 mm) than those treated with conventional balloon angioplasty (p less than .02). Histologic examination 4 weeks after the procedure revealed less fibrocellular proliferation after laser thermal angioplasty, whereas those vessels treated with balloon angioplasty demonstrated evidence of prior fracture and dissection of the vessel wall with more of a fibrocellular proliferative response.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1987

Distinguishing lymphatics from blood vessels in normal and diseased skin.

If it were true that lymphatics are essential for the removal of macromolecules and in this way the oncotic and hydrostatic pressures within the interstitium are determined; if it were true that lymphatics are the principal pathway for the exit of antigen and of macrophages and hence, important for cell mediated immunity, then on both accounts the lymphatics are of great significance. There must be some anxiety that none of this can be confirmed and that some tissues such as the brain and the eye do not need lymphatic vessels as such. We must also note that in many diseases the lymphatic system seems to be severely disrupted, and yet it is difficult to show that the tissues are severely compromised. One wonders to what extent blood vessels or any other system, such as the mononuclear phagocytic system, can take over the role of the lymphatic. To answer these questions one needs to be able to identify the lymph clearance system as distinct from the blood supply system. Although this is easy in health, it becomes very difficult in disease.

Humans↗
PubMed1987

Laser thermal angioplasty: from the experimental model to early human experience.

The use of flexible fiberoptic fibers to transmit laser energy for the ablation of atherosclerotic obstructions has significant potential in the cardiovascular area; initial clinical trials indicate that some of the early limitations of laser angioplasty can be solved. Laser thermal angioplasty has now been clinically demonstrated to be a safe and effective adjunct to balloon angioplasty for the management of symptomatic femoropopliteal disease. Based on the earliest experience of laser thermal angioplasty in human coronary arteries, the procedure is feasible. It seems clear that considerable technologic advancements in catheter design are required to improve the safety and efficacy of this new technique.

Angioplasty, Balloon↗
PubMed1987

Diagnosis of pericardial effusions from routine gated blood-pool imaging.

Gated blood-pool scintigraphy (GBPS) is often obtained as the initial test to evaluate symptoms suggestive of left ventricular dysfunction. Since large pericardial effusions may also cause such symptoms, the ability to recognize them on routine GBPS is of clinical importance. Characteristic features of the "halo" sign surrounding the cardiac blood pool were developed, based on the GBPS of patients with known pericardial effusions. These criteria were then applied blindly to 154 consecutive patients who underwent both GBPS and echocardiography. All five patients with large effusions (approximately greater than 500 ml) were correctly identified by GBPS (sensitivity 100%); for patients with moderate effusions (approximately 150-500 ml), the sensitivity was only 33% (3/9). There were three false positives (specificity 98%). We conclude that large pericardial effusions can be identified with high sensitivity and specificity on routine GBPS. Although echocardiography remains the method of choice for the diagnosis of effusions, inspection for characteristics suggesting their presence on GBPS should be part of routine interpretations.

Echocardiography↗
PubMed1987

Punched-out porokeratosis. A histological variant of disseminated superficial actinic porokeratosis.

This paper describes an unusual histological variant of disseminated superficial actinic porokeratosis in which there were areas of full-thickness coagulative epidermal necrosis. The diagnosis of porokeratosis was confirmed with a further biopsy, which demonstrated a coronoid lamella and some underlying basal cell liquefaction. The significance of the pathology is discussed.

Epidermal Cells↗
PubMed1986

Percutaneous laser thermal angioplasty: initial clinical results with a laser probe in total peripheral artery occlusions.

A metal-tipped laser fibre was used during percutaneous angioplasty of femoral/popliteal or iliac artery occlusions in 56 patients. Primary success was achieved in 50 (89%) of these total occlusions, providing a channel for subsequent balloon dilatation. Before the procedure, 18 lesions had been judged untreatable by conventional angioplasty and four of the six failures were in these. Complications directly attributable to the laser probe were one case of vessel perforation and two cases of entry into vessel walls; these had no sequelae. Other acute complications were a distal thrombosis in a non-heparinised patient, requiring local streptokinase treatment, and two reocclusions and one transient peripheral embolic episode in the first 24 hours. The laser probe technique has potential for increasing the proportion of patients suitable for angioplasty.

Aged↗
PubMed1986

Comparison of determinants of myocardial oxygen consumption during arm and leg exercise in normal persons.

Arm exercise assumes an increasingly important role in clinical cardiology as it is used in both exercise testing and training of patients with coronary artery disease. The effects of arm exercise on myocardial oxygen consumption are not well understood; they may differ from the effects of leg exercise. Previous studies have shown that the ischemic threshold is higher in patients performing arm exercise and leg exercise at the same heart rate-blood pressure product. The contribution of other determinants of myocardial oxygen consumption--left ventricular (LV) peak meridional systolic wall stress and contractility--to these observed differences were studied. Thirty healthy subjects exercised to the same peak rate-pressure product during dynamic upper- and lower-extremity exercise. Peak workload was lower during arm exercise (100 +/- 16 W) than during leg exercise (170 +/- 21 W, p less than 0.001). LV wall stress did not differ during either form of exercise (197 +/- 44 vs 204 +/- 33 dynes/cm2 X 10(3), arm vs leg, respectively). This was also true of contractility as assessed by the velocity of circumferential fiber shortening (2.8 +/- 0.6 vs 2.5 +/- 0.4 circ/s, arm vs leg, respectively) and the preejection period/LV ejection time ratio (0.33 +/- 0.11 vs 0.31 +/- 0.07, arm vs leg, respectively). Normal subjects exercising to a similar rate-pressure product showed the same levels of LV wall stress and contractility for arm and leg exercise despite the lower workload performed with arm exercise.

Adult↗
PubMed1986

Lymphoedema.

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Humans↗
PubMed1986

Monoclonal antibodies to bovine platelet factor 4: species interactions to platelets and megakaryocytes using indirect immunocytofluorescence.

Murine monoclonal antibodies (mAb) were raised to a purified product of bovine PF-4, a 9,500 dalton protein with heparin neutralization activity comparable to that of human PF-4. Using a non-radioactive slide immunoenzymatic assay, four major classes of mAb could be identified when comparisons were made between purified antigens of PF-4 and beta-TG-like protein from both bovine and human species. Type 1 cross-reacted with all four antigens; type 2 reacted with PF-4s; type 3 reacted with only bovine PF-4 and beta-TG-like protein; and type 4 reacted only with bovine PF-4. Differences in immunoreactivities of types 1, 2 and 3 were retained throughout the growth of succeeding clones and in ascitic fluids. Using a modified factor Xa, S-2222 chromogenic substrate-heparin inhibition assay, no mAb was found to block PF-4's ability to neutralize heparin. mAbs representative of types 1, 2 and 3 were successfully raised in stable cell lines from at least second generation clones. These were purified with protein A agarose and found to be IgG1. By indirect immunocytofluorescence a purified type 2 mAb, 2E7, was found to specifically stain granules of human platelets and megakaryocytes, as well as masses (putative platelets within late stage megakaryocytes) without staining other cellular types in either bone marrow or peripheral blood. Species comparisons displayed positive staining for human, rat, and rabbit platelets and megakaryocytes, and negative staining for mouse, guinea pig and dog platelets and megakaryocytes. It seems likely that mAb, 2E7, is directed against an epitope, common to PF-4 of bovine, human, rabbit and rat.

Animals↗