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Biomedical subjects

T Ryan

Publications and source records attributed to T Ryan.

At least 109 records · Page 6Linked to original sources
PubMed1992

Agitation and postdexamethasone cortisol levels in Alzheimer's disease.

The clinical correlates of hypothalamic-pituitary-adrenal (HPA) functioning were examined in 29 patients with probable Alzheimer's disease. The 8:00 a.m. postdexamethasone cortisol levels of these patients were highly correlated with higher agitation scores but not with the degree of depressed mood or memory impairment. The possible neural basis for the association between hypercortisolism and behavioral disturbance in Alzheimer's disease warrants further exploration and replication.

Alzheimer Disease↗
PubMed1992

Sudden infant death syndrome in New Jersey: 1991.

Sudden infant death syndrome (SIDS) is the leading cause of death in infants one month to one year of age. The New Jersey Sudden Infant Death Syndrome Resource Center gathers epidemiological data on all SIDS deaths in New Jersey, noting differences in population and countries.

Humans↗
PubMed1991

Thymus-dependent network responses to a monoclonal cross-reactive antiidiotypic antibody.

BALB/c mice were inoculated i.p. with a cross-reactive anti-Idiotypic mAb (designated FD5-1) in the absence of Ag or adjuvants. Injection with unmodified FD5-1 resulted in the induction of serum antibodies reactive with both FD5-1 (Ab3) and the hapten DNP (Ab1'). Endpoint titers of the Ab3 response showed an increase in serum IgM, which was dose-responsive to both the number of injections and the amount of FD5-1 antibody injected. The serum IgM Ab3 response was found to be thymus dependent and idiotypically specific for FD5-1. Athymic mice injected with FD5-1 were unable to produce a serum IgM Ab3 response, whereas their euthymic littermates produced strong Ab3 responses. Serum Ab3 responses and Ab1' were detectable only in the IgM isotype; no specific IgG responses were observed. Indeed, IgG recognized by FD5-1 appeared to be suppressed by FD5-1. Injection of mice with FD5-1 modulated serum IgM responses to DNP, (4-hydroxy-3-nitrophenyl)acetyl (NP), 4-ethoxymethylene-2-phenyloxazol-5-one (OX), phosphorylcholine (PC), and alpha 1,3-dextran (DEX) in a thymus-dependent manner. FD5-1 injection induced IgM responses against DNP, (4-hydroxy-3-nitrophenyl)acetyl (NP), 4-ethoxymethylene-2-phenyloxazol-5-one, and DEX but decreased IgM binding to PC. No detectable Ab1' responses to any of the aforementioned molecules were found when the same sera were probed for IgG. The specificity of serum Ab1' from FD5-1-injected mice was evaluated by antigenic inhibition. Binding of serum Ab1' to DNP-BSA was inhibitable by DNP-lysine, whereas equivalent concentrations of lysine alone had no inhibitory effect. The antigenic specificity of IgM from normal serum binding to PC-BSA was demonstrated by inhibition with free PC, and the binding of Ab1' from FD5-1-injected mice to DEX-coated plates was shown to be inhibitable by DEX. We have described in vivo network perturbation in adult BALB/c mice injected with anti-Id antibody in the absence of Ag or adjuvants. Our findings show that injection of the cross-reactive anti-Id FD5-1 can induce thymus-dependent Ag-specific responses. In two systems where FD5-1 functions as an anti-anti-anti-Id antibody (PC and DEX), thymus-dependent responses were also observed. FD5-1 injection suppressed antibodies binding to PC, whereas DEX-specific responses were induced.

Animals↗
PubMed1991

Segmental wall motion abnormalities in the absence of clinically documented myocardial infarction: clinical significance and evidence of hibernating myocardium.

To determine the frequency and significance of left ventricular wall motion abnormalities in patients without clinical evidence of myocardial infarction, we reviewed the two-dimensional echocardiograms of 252 patients who had no history or electrocardiographic evidence of myocardial infarction and who subsequently underwent coronary angiography. Seventy-seven patients (31%) had one or more segmental wall motion abnormalities. Sixty-six of the 77 patients (86%) had significant coronary artery disease (greater than or equal to 50% luminal diameter stenosis). Seventy-four percent of the patients with coronary artery disease had multivessel disease. The left ventricle was divided into anterior and posterior regions. In the 66 patients, there were 77 separate regions with wall motion abnormalities (49 hypokinesis, 22 akinesis, 6 dyskinesis), including 60 regions (78%) supplied by coronary vessels with greater than or equal to 70% stenosis. Thirty-two patients underwent coronary artery bypass surgery or percutaneous transluminal coronary angioplasty. Follow-up echocardiograms were obtained in 19 patients who had wall motion abnormalities involving 22 regions. Twenty of the 22 regions were revascularized. Wall motion improved in 17 of 20 regions (85%) and returned to normal in 15 regions (75%). We conclude that segmental wall motion abnormalities may be detected by echocardiography in up to one third of patients evaluated for suspected coronary artery disease without documented myocardial infarction. These abnormalities are associated with a high likelihood of multivessel disease as well as with significant narrowing of the artery supplying the region demonstrating abnormal wall motion. Improvement in segmental wall motion abnormalities after revascularization suggests that these areas represent regions of hibernating myocardium.

Adult↗
PubMed1991

RTOG quality assurance guidelines for clinical trials using hyperthermia for deep-seated malignancy.

Quality assurance has been vague or lacking in many previous hyperthermia trials. Recent publications by the Hyperthermia Physics Center, the Center for Devices and Regulatory Health, and the Radiation Therapy Oncology Group have described general guidelines for quality assurance in equipment reliability and reproducibility, superficial applications, and microwave techniques. The present report details quality assurance factors that are believed to be important for hyperthermia of deep clinical sites, defined as extending at least 3 cm beyond the skin surface. This document will discuss patient and physician factors, as well as thermometric accuracy, assessment of specific absorption rates (SAR), assurance of adequate coverage of tumors by the energy deposition pattern of the treatment device, and recommended documentation of the location, quantity, and frequency of treatment, specifically oriented to deep hyperthermia. The recommendations are structured to facilitate compliance in multiinstitutional trials.

Clinical Protocols↗
PubMed1991

RTOG quality assurance guidelines for interstitial hyperthermia.

This document specifies the current recommendations for quality assurance for hyperthermia administration with interstitial techniques as specified by the Radiation Therapy Oncology Group (RTOG). The document begins by providing a brief description of the physical principles behind the use of the three most commonly used methods of interstitial hyperthermia: radiofrequency (RF-LCF), microwave antennas, and ferromagnetic seeds. Emphasis is placed on features that effect quality assurance. Specific recommendations are provided for: a) Pretreatment planning and equipment performance checks, b) Implant considerations and documentation, c) Thermometry, and d) Safety procedures. Specific details regarding quality assurance issues that are common to all local and regional hyperthermia methods are outlined in previous documents sponsored by the RTOG. It is anticipated that technological advances may lead to future modifications of this document.

Documentation↗
PubMed1991

End-systolic regional wall stress-length and stress-shortening relations in an experimental model of normal, ischemic and reperfused myocardium.

Assessment of left ventricular function is influenced by a number of hemodynamic factors. The purpose of this study was to evaluate the end-systolic regional wall stress-dimension relation in a series of 25 mongrel dogs. In Group A (n = 18) the regional wall stress-velocity of circumferential fiber shortening relation was measured before and after three interventions: volume infusion, metoprolol infusion and dobutamine infusion. The electrocardiogram, left ventricular pressure and its first derivative (dP/dt), arterial pressure and echocardiograms were recorded at baseline and after phenylephrine administration (to increase afterload). For each dog values for regional wall stress were plotted against the velocity of circumferential fiber shortening. For all dogs the relations were inversely linear (r = -0.65 to -0.98). Volume infusion increased end-diastolic volume (p less than 0.05) without shifting the slope or intercept of the relation, indicating its independence from preload. Dobutamine caused a shift in the intercept to the right but no change in slope and metoprolol shifted the relation to the left without altering the slope. The effect of ischemia and reperfusion on the end-systolic regional wall stress-length relation was examined in Group B (n = 7), at baseline, after 5 min of mid-left anterior descending coronary artery occlusion and after 10 min of reperfusion. Afterload was increased by hydraulic aortic occlusion. Regional wall stress was lowest at baseline, highest during ischemia and intermediate after reperfusion (100.2 +/- 32.1, 193.5 +/- 81.5, 141.9 +/- 67.6 kdyn/cm2, respectively, p less than 0.001). The end-systolic regional wall stress-length relation was linear during baseline, ischemia and reperfusion (r = 0.96, 0.95, 0.98, respectively, p less than 0.05). Ischemia caused an increase in the slope and a shift in the intercept to the right compared with baseline. Reperfusion represented an incomplete return toward baseline. This study demonstrates that the regional wall stress-velocity of circumferential fiber shortening relation is linear, independent of preload, incorporates afterload and is sensitive to changes in contractility. In addition, the regional wall stress-length relation can be measured in a nonhomogeneously contracting left ventricle and is predictably altered by ischemia and reperfusion. This relation may prove useful to determine whether alterations in regional systolic function result from changes in local load or contractility in the left ventricle with a regional wall motion abnormality.

Animals↗
PubMed1991

Regulation of atrial natriuretic peptide release in normal humans.

Atrial volume, pressure, and heart rate are considered the most important modulators of atrial natriuretic peptide (ANP) release, although their relative role is unknown. Continuous positive-pressure breathing in normal humans may cause atrial pressure and atrial volume to go in opposite directions (increase and decrease, respectively). We utilized this maneuver to differentially manipulate atrial volume and atrial pressure and evaluate the effect on ANP release. Effective filling pressure (atrial pressure minus pericardial pressure) was also monitored, because this variable has been proposed as another modulator of ANP secretion. We measured right atrial (RA) pressure, RA area, esophageal pressure (reflection of pericardial pressure), and RA and peripheral venous ANP in seven healthy adult males at rest and during continuous positive-pressure breathing (19 mmHg for 15 min). Continuous positive-pressure breathing decreased RA area (mean +/- SE, *P less than 0.05) 13.6 +/- 1.1 to 10.5 +/- 0.8* cm2, increased RA pressure 4 +/- 1 to 16 +/- 1* mmHg, increased esophageal pressure 2 +/- 1 to 12 +/- 1* mmHg, and increased effective filling pressure 2 +/- 0 to 4 +/- 1* mmHg. RA ANP increased from 67 +/- 17 to 91 +/- 18* pmol/l and peripheral venous ANP from 43 +/- 4 to 58 +/- 6* pmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Echocardiographic detection of coronary artery disease during dobutamine infusion.

BACKGROUND: Two-dimensional echocardiography performed during dobutamine infusion has been proposed as a potentially useful method for detecting coronary artery disease. However, the safety and diagnostic value of dobutamine stress echocardiography has not been established. METHODS AND RESULTS: In this study, echocardiograms were recorded during step-wise infusion of dobutamine to a maximum dose of 30 micrograms/kg/min in 103 patients who also underwent quantitative coronary angiography. The echocardiograms were digitally stored and displayed in a format that allowed simultaneous analysis of rest and stress images. Development of a new abnormality in regional function was used as an early end point for the dobutamine infusion. No patient had a symptomatic arrhythmia or complications from stress-induced ischemia. Significant coronary artery disease (greater than or equal to 50% diameter stenosis) was present in 35 of 55 patients who had normal echocardiograms at rest. The sensitivity and specificity of dobutamine-induced wall motion abnormalities for coronary artery disease was 89% (31 of 35) and 85% (17 of 20), respectively. The sensitivity was 81% (17 of 21) in those with one-vessel disease and 100% (14 of 14) in those with multivessel or left main disease. Forty-one of 48 patients with abnormal echocardiograms at baseline had localized rest wall motion abnormalities. Fifteen had coronary artery disease confined to regions that had abnormal rest wall motion, and 26 had disease remote from these regions. Thirteen of 15 patients (87%) without remote disease did not develop remote stress-induced abnormalities, and 21 of 26 (81%) who had remote disease developed corresponding abnormalities. CONCLUSIONS: Echocardiography combined with dobutamine infusion is a safe and accurate method for detecting coronary artery disease and for predicting the extent of disease in those who have localized rest wall motion abnormalities.

Adrenergic beta-Antagonists↗
PubMed1990

Improvement in rest and exercise-induced wall motion abnormalities after coronary angioplasty: an exercise echocardiographic study.

Exercise echocardiography was performed in 36 patients to evaluate functional improvement after coronary angioplasty. Thirty-one patients (86%) had provokable ischemia before angioplasty including 22 with an abnormal exercise electrocardiographic test (angina or ST depression), 25 with an abnormal exercise echocardiogram (exercise-induced wall motion abnormalities) and 16 with both tests abnormal. Nineteen patients had no induced ischemia after angioplasty. Seventeen (47%) continued to have ischemia that was limited in 12 to exercise-induced wall motion abnormalities, which were less severe compared with those of preangioplasty studies. Fifteen (65%) of 23 patients had improvement in rest wall motion abnormalities after angioplasty. The rest to immediate postexercise change in global wall motion score was significantly improved after angioplasty. The change in regional wall motion score was significantly improved after angioplasty in patients with single vessel right or left circumflex coronary artery disease and approached significant improvement (p = 0.06) in those with single vessel disease of the left anterior descending coronary artery. Exercise echocardiography improves the sensitivity of functional testing for ischemia, aids in localizing the ischemic zone and documents improvement in regional function after coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1990

Intraoperative radiation therapy and hyperthermia. Morbidity and mortality from this combined treatment modality for unresectable intra-abdominal carcinomas.

This is a report of a phase I trial of intraoperative radiation therapy in combination with intraoperative hyperthermia for the treatment of locally advanced, unresectable intra-abdominal carcinomas. Using an ultrasound transducer system specifically designed for intraoperative applications, 19 patients have been successfully treated, demonstrating the feasibility of this combination modality. The morbidity (58%) and mortality (11%) rates reported in this series are comparable to rates reported in series of similar patients receiving intraoperative radiation therapy alone. There is still a great need for considerable technological development to enable the use of intraoperative hyperthermia to treat large, complexly shaped intra-abdominal tumors, and phase II and III trials of this combination treatment modality should be performed.

Abdominal Neoplasms↗
PubMed1990

Prognostic value of a normal exercise echocardiogram.

Follow-up information was obtained from 148 patients who had normal resting and post-treadmill exercise echocardiograms to determine the prognostic value of a normal exercise echocardiogram in patients evaluated for suspected coronary artery disease. There were 77 men and 71 women with a mean age of 52.5 years and a pretest likelihood of coronary artery disease of 39%. Patients were followed for a mean duration of 28.4 +/- 8.5 months. The exercise ECG was abnormal in 69 patients (47%) including 28 who had ischemic responses. Cardiac events occurred in six patients, three with normal and three with abnormal exercise ECGs. Events occurred only in those patients (6 of 68) who exercised to work loads less than 6 METs or who achieved less than 85% of the age-predicted maximal heart rate. Three patients had coronary artery bypass grafting for angina from 10.5 to 22.5 months after echocardiography. A fourth patient had bypass grafting for mild single-vessel disease at the time of mitral valve replacement. Two patients had myocardial infarctions (0.85% per year) at 7.5 and 41 months after echocardiography. There were no deaths. Coronary revascularization is infrequently required in the 28 months after a normal exercise echocardiogram. A normal exercise echocardiogram in a patient with good exercise capacity was predictive of an excellent prognosis, even in those who had abnormal exercise ECGs. Myocardial infarction and death were rare events, even in patients with decreased exercise capacity.

Adult↗
PubMed1990

Distinguishing viable from infarcted myocardium after experimental ischemia and reperfusion by using nuclear magnetic resonance imaging.

Early reperfusion has the potential for salvaging ischemic myocardium at risk for infarction. To test the ability of nuclear magnetic resonance (NMR) imaging to differentiate between stunned and infarcted myocardium early after reperfusion, 16 mongrel dogs underwent transient occlusion of the left anterior descending artery or a diagonal branch for 30, 60 or 180 min followed by reperfusion. To identify the area at risk for infarction and to assess the extent of hypoperfusion and reperfusion, two-dimensional and contrast echocardiography were performed at baseline study, during coronary occlusion and at three separate times during reperfusion (before NMR imaging, immediately after NMR imaging and 12 to 14 h later). Wall thickening in the control and ischemic zones and the circumferential extent of abnormal wall motion were analyzed at each time point using short-axis echocardiograms. Nuclear magnetic resonance imaging at 1.5 tesla was performed 2 to 3.5 h (mean 2.7 +/- 0.5) after reperfusion. Short-axis, multislice spin-echo images (TE 26 and TE 60) were obtained. Signal intensity was measured in the control and ischemic areas and expressed as a percent difference compared with normal myocardium. All dogs demonstrated a significant decrease in wall thickening and abnormal wall motion before and after NMR imaging. Seven of the eight dogs with infarction had an area of increased signal intensity on TE 60 images. The mean percent difference in signal intensity compared with adjacent normal myocardium was 127 +/- 68% (p = 0.002). None of the eight dogs without infarction had a visually apparent change in signal intensity on TE 60 images (mean percent difference versus control area 13 +/- 11%), despite regional systolic dysfunction documented by echocardiography at the time of imaging. The area of increased signal intensity correlated with infarct size (r = 0.69), although overestimation by NMR imaging occurred. The area of increased signal intensity did not correlate with the extent of echocardiographic contrast defect during coronary occlusion (risk area). This study demonstrates that NMR imaging can be applied early after coronary reperfusion to assess the potential for recovery of dysfunctional myocardium. In addition, by using a TE 60 multislice spin-echo imaging sequence at 1.5 tesla, quantification of the extent of infarction also may be possible.

Animals↗