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Biomedical subjects

T Ryan

Publications and source records attributed to T Ryan.

At least 181 records · Page 10Linked to original sources
PubMed1977

Host factor for coliphage Q beta RNA replication: presence in procaryotes and association with the 30S ribosomal subunit in Escherichia coli.

The Host Factor required for in vitro coliphage Q beta RNA replication, a heat-stable RNA binding protein present in uninfected Escherichia coli, has been detected by both immunological and functional tests in Acinetobacter calcoaceticus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Pseudomonas putida. It was not detectable by these criteria in Bacillus stearothermophilus, Bacillus subtilis, Caulobacter crescentus, Micrococcus lysodeikticus, Rhodopseudomonas capsulata or Saccharomyces cerevisiae. In Escherichia coli the Host Factor protein has been shown to be associated with ribosomes. It is demonstrated here that this association is specific for the 30S ribosomal subunit.

Acinetobacter↗
PubMed1977

Host factor for coliphage Qbeta RNA replication as an aid in elucidating phylogenetic relationships: the genus Pseudomonas.

Host Factor (HF) is a heat-stable RNA-binding protein required along with Qbeta replicase for in vitro transcription of coliphage Qbeta RNA. We have found that HF activity and antigenicity are conserved among certain Gram-negative bacterial species. We examined selected species within the genus Pseudomonas for the presence of the HF polypeptide's antigenicity and Qbeta RNA replication function. While we were unable to detect either of these in Pseudomonas diminuta or Pseudomonas vesicularis, the other eleven species tested contained cross-reacting material to Escherichia coli HF. Furthermore, in six of these eleven species we were able to detect HF activity. The detection of HF structure and function allowed the examined species to be grouped into three categories which we have called 'sets'. The results correlate well with those of previous studies on ribosomal RNA homology (Palleroni et al., 1973).

Antigens, Bacterial↗
PubMed1975

Angioma serpiginosum--familial incidence.

In this paper we present the first record of familial incidence in angioma serpiginosum observed in two families. The clinical and histological features are described.

Adult↗
PubMedDate not supplied

Dynamic three-dimensional echocardiographic reconstruction of congenital cardiac septation defects.

Dynamic three-dimensional echocardiographic reconstructions of 27 cardiac septation defects were performed in 19 sedated infants and children. Using a subxiphoid rotational scanning approach, complete visualization of the entire shape and breadth of the defect was attained in 11 of 16 ventricular septal defects and 9 of 11 atrial septal defects. This technique enabled the operator to cut slices from the three-dimensional block of echocardiographic data in order to present septation defects in a region- or lesion-oriented fashion. Poor baseline two-dimensional image quality and certain small septation defects that were readily obscured by nearby structures led to inadequate three-dimensional reconstructions. The application of dynamic three-dimensional echocardiography for assessment of cardiac septation defects uniquely provided (1) the ability to present en face views of atrial and ventricular septal defects; and (2) a means by which intracardiac anatomy can be displayed in a region- and lesion-oriented fashion for interventional and surgical planning purposes.

Adolescent↗
PubMedDate not supplied

Ondansetron for nausea and vomiting associated with moderately emetogenic cancer chemotherapy.

This multicenter, randomized, double-blind study compared the efficacy and tolerability of ondansetron 8 mg twice daily for 3 days with placebo in preventing nausea and vomiting in 81 patients receiving cyclophosphamide-doxorubicin-based chemotherapy. The first dose of study drug was administered 30 minutes before the initiation of chemotherapy. Patients received a rescue antiemetic if the investigator deemed it necessary or if the patient experienced more than two emetic episodes during the 3-day study. Sixty-one percent of patients treated with ondansetron compared with 6% of patients receiving placebo (P < 0.001) had no emetic episodes during the 3-day study. Among patients with at least one emetic episode, the mean time to emesis was 24 hours 18 minutes in the ondansetron group compared with 8 hours 1 minute in the placebo group (P < 0.001). In the intent-to-treat analysis, 78% of patients in the ondansetron group and 29% of patients in the placebo group completed the study with no need for rescue therapy. Clinical laboratory and adverse-event profiles were similar between groups. The most common adverse event was headache, occurring in 23% of ondansetron patients and 24% of placebo patients. This study is the first double-blind, placebo-controlled trial to demonstrate that ondansetron 8 mg twice daily is effective in the prevention of nausea and vomiting associated with cyclophosphamide-doxorubicin-based chemotherapy. The twice-daily regimen may encourage patient compliance and may be more cost-effective than regimens that need to be given three times daily.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

Pharmacologically induced myocardial ischemia: a comparison of dobutamine and dipyridamole.

The purpose of our study was to compare the ability of dobutamine and dipyridamole infusion to induce myocardial ischemia. In a population of 16 anesthetized open-chest swine, a coronary artery stenosis sufficient to abolish the hyperemic response to a 15-second total occlusion was created. Heart rate, systolic blood pressure, and dP/dt were recorded. Myocardial segment shortening was determined by sonomicrometry in all animals. In a subset of seven animals regional myocardial blood flow was measured by injection of radiolabeled microspheres. Dipyridamole was infused according to a high-dose protocol. After a washout period and reestablishment of a baseline state, dobutamine was infused incrementally. There was no significant difference between the baseline states. Dipyridamole did not affect heart rate but did significantly decrease blood pressure and rate-pressure product. Myocardial segment shortening decreased in the ischemic zone by 0.07 +/- 0.08 (p = 0.004). Dobutamine infusion significantly increased heart rate, blood pressure, and rate-pressure product. Myocardial segment shortening in the ischemic zone decreased by 0.17 +/- 0.09 (p < 0.001). Dobutamine decreased blood flow in the ischemic zone relative to baseline. Both dobutamine and dipyridamole infusion resulted in myocardial ischemia. The magnitude of the ischemic response is greater for dobutamine than for dipyridamole.

Animals↗
PubMedDate not supplied

Color coding of digitized echocardiograms: description of a new technique and application in detecting and correcting for cardiac translation.

Color coding is a new software application for digitized echocardiograms that displays a reference image of end diastole throughout the cardiac cycle. With color-coded digitized echocardiograms, we determined the frequency of, and corrected for cardiac translation in 21 bicycle stress echocardiograms in patients who were known to be without significant coronary artery disease or wall motion abnormalities. Translation was present in 4%, 40%, and 74% of rest, postexercise, and peak exercise images, respectively, and was noted most frequently in the apical views, 59% of four-chamber views and 40% of two-chamber views. Interobserver and intraobserver agreement for detection of translation was 81% and 86%, respectively. Translation was corrected by shifting digitized images to eliminate transverse displacement of the mitral valve anulus and restore normal basal-to-apical shortening. Ventricular contraction was assessed as normal in 92% of the images in which correction for translation was performed. In the remaining images, poor image quality (3%) and apparent wall motion abnormalities (5%) prevented the studies from being graded as normal. We conclude that color coding of digitized echocardiograms is a useful new technique that can be applied to detect and correct for cardiac translation.

Data Display↗
PubMedDate not supplied

Detection of coronary artery disease with upright bicycle exercise echocardiography.

This study examined the advantages and limitations of upright bicycle exercise echocardiography in the evaluation of a large series of patients with known or suspected coronary artery disease. The study population consisted of 309 patients (231 men, mean age 57 +/- 11 years) who underwent exercise echocardiography within 8.5 +/- 16.1 days of coronary angiography. All stress electrocardiographic, echocardiographic, and angiographic data were reinterpreted in a blinded manner by the investigators. No patient was excluded because of poor echocardiographic image quality. Wall motion was analyzed at baseline, peak exercise, and immediately after exercise with a 16-segment model, and a regional wall motion score index was calculated at each stage. Abnormalities were ascribed to the distribution of the three coronary arteries and correlated with qualitative angiography. There were 126 patients with wall motion abnormalities at rest and 211 (75%) with coronary artery disease. The stress electrocardiogram (ECG) was negative in 61, positive in 144, and nondiagnostic in 104, yielding a sensitivity of 40% and a specificity of 89%. Echocardiography was normal in 76 of 98 patients without coronary disease (78% specificity) and abnormal in 193 of 211 patients with disease (91% sensitivity). Sensitivity was higher among patients with multivessel disease compared with those with single vessel disease (95% versus 86%, respectively, p = 0.03). Among patients with normal wall motion at rest (n = 183), sensitivity was 83% and specificity was 84%. Of the 104 patients with a nondiagnostic stress ECG, echocardiography correctly identified 95% of those with coronary disease and 75% of those without disease. Among 82 patients with a wall motion abnormality at rest, an additional exercise-induced wall motion abnormality developed in 32 of 46 patients (70%) with multivessel disease and seven of 32 (22%) with single-vessel disease. Overall, echocardiography detected 258 of 392 (66%) individual coronary lesions. Accuracy was higher for lesions in the left anterior descending and right coronary arteries (both 79%) compared with the left circumflex artery (36%, p < 0.001). In conclusion, upright bicycle exercise echocardiography is an accurate technique for the evaluation of patients with known or suspected coronary artery disease and is especially valuable in patients with a nondiagnostic stress ECG. The test provides supplemental information on the extent and location of coronary lesions and is useful in patients with and without prior myocardial infarction.

Coronary Angiography↗
PubMedDate not supplied

Comparison of regional and global left ventricular function by serial echocardiograms after reperfusion in acute myocardial infarction.

Fifty patients undergoing successful reperfusion therapy (percutaneous transluminal coronary angioplasty 20, thrombolysis 10, combined 20) for acute myocardial infarction were evaluated with serial two-dimensional echocardiograms performed early (less than 24 hours, mean 8 hours) and late (greater than 3 days, mean 6 days) after presentation. Treatment occurred within 12 hours of the onset of symptoms with most patients achieving reperfusion in less than 6 hours (mean 4.7 hours) from the onset of pain. Reperfusion was demonstrated short-term by angiography in 42 of 50 patients (84%). Four patients had clinical signs of reperfusion and subsequent angiographic confirmation. An additional four patients with "stuttering" infarct courses were treated late by percutaneous transluminal coronary angioplasty. Echocardiograms were analyzed for global performance by calculation of fractional area change at the papillary muscle level and ejection fraction (biplane Simpson's rule) in 18 patients in whom this analysis could be performed. Measurements of regional function included fractional shortening at the base (n = 37), regional wall motion index (n = 50) and percent of normal functioning myocardium (n = 50). Overall there was a significant improvement in regional wall scores and percent of functioning myocardium (regional wall motion index 1.73 to 1.43, p less than 0.001 and percent of functioning myocardium 0.61 to 0.70, p less than 0.001) but only a trend toward improvement when global function was assessed by ejection fraction (0.42 to 0.48, p less than 0.14).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Regional wall motion index for infarct and noninfarct regions after reperfusion in acute myocardial infarction: comparison with global wall motion index.

A regional wall motion index has been derived from two-dimensional echocardiograms by use of a 16-segment model that was subdivided into anterior (nine segments) and infero-postero-lateral (seven segments) regions. This new method is compared with the use of a previously described global wall motion index for the analysis of serial echocardiograms after reperfusion in 23 patients who had acute myocardial infarction. Mean global index improved from 1.84 +/- 0.46 to 1.56 +/- 0.37 at 24 hours (p less than 0.01) and to 1.50 +/- 0.29 after 3 days to 7 days (p less than 0.02), whereas mean regional index for infarct regions improved from 2.28 +/- 0.73 to 1.82 +/- 0.58 at 24 hours (p less than 0.01) and to 1.70 +/- 0.42 after 3 to 7 days (p less than 0.01), with no significant change in the noninfarct index (1.34 +/- 0.32 initially and 1.28 +/- 0.36 after 3 to 7 days). Although both global and regional indexes effectively demonstrate early recovery of left ventricular function, (within 24 hours in many patients), the regional index for infarct regions is higher than the global index and effectively distinguishes between infarct and noninfarct segments. An overlap index in which an additional apical segment is included in the anterior region (10 segments) for anterior infarctions and in the infero-postero-lateral region (eight segments) for inferior infarctions results in a greater differentiation between infarct and noninfarct regions, with the mean initial noninfarct overlap index (1.17 +/- 0.33) significantly less than the nonoverlap index.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMedDate not supplied

Comparison of digital with videotape echocardiography in patients with chest pain in the emergency department.

We prospectively compared digital echocardiographic images, by a minimal digital-acquisition strategy, with videotape images to determine the diagnostic utility of digital imaging in patients admitted to the emergency department with chest pain. Digital acquisition has many potential advantages for evaluating echocardiographic images, especially in the acute-care setting. It is not yet known how much the imaging study can be condensed with digital technology and still provide the necessary information needed for clinical echocardiographic diagnosis. One hundred seventeen patients with diagnoses consisting of coronary artery disease, pericardial disease, and valvular disease were studied. Overall agreement between videotape and digital recordings with regard to normal versus abnormal wall motion was 94% (p < 0.001). The wall motion score index, a semiquantitative measure of global function, also correlated well (r = 0.94). Complete concordance was noted in all patients with aortic stenosis and pericardial effusion. Digital echocardiographic imaging, by a minimal-acquisition strategy, is an accurate summary of the complete echocardiographic examination and provides the relevant diagnostic data needed for the assessment of patients with chest pain in the emergency department.

Chest Pain↗