Biomedical subjects

J J McCarthy

Publications and source records attributed to J J McCarthy.

At least 19 recordsLinked to original sources

PubMed1991

Identification of false positive exercise tests with use of electrocardiographic criteria: a possible role for atrial repolarization waves.

Atrial repolarization waves are opposite in direction to P waves, may have a magnitude of 100 to 200 mu V and may extend into the ST segment and T wave. It was postulated that exaggerated atrial repolarization waves during exercise could produce ST segment depression mimicking myocardial ischemia. The P waves, PR segments and ST segments were studied in leads II, III, aVF and V4 to V6 in 69 patients whose exercise electrocardiogram (ECG) suggested ischemia (100 mu V horizontal or 150 mu V upsloping ST depression 80 ms after the J point). All had a normal ECG at rest. The exercise test in 25 patients (52% male, mean age 53 years) was deemed false positive because of normal coronary arteriograms and left ventricular function (5 patients) or normal stress single photon emission computed tomographic thallium or gated blood pool scans (16 patients), or both (4 patients). Forty-four patients with a similar age and gender distribution, anginal chest pain and at least one coronary stenosis greater than or equal to 80% served as a true positive control group. The false positive group was characterized by 1) markedly downsloping PR segments at peak exercise, 2) longer exercise time and more rapid peak exercise heart rate than those of the true positive group, and 3) absence of exercise-induced chest pain. The false positive group also displayed significantly greater absolute P wave amplitudes at peak exercise and greater augmentation of P wave amplitude by exercise in all six ECG leads than were observed in the true positive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function↗

PubMed1990

Comparison of coronary angiography and early oral dipyridamole thallium-201 scintigraphy in patients receiving thrombolytic therapy for acute myocardial infarction.

We evaluated 50 consecutive patients who received thrombolytic therapy for acute myocardial infarction using thallium-201 single photon emission computed tomography in combination with oral dipyridamole (300 mg) to assess the frequency of residual myocardial ischemia. Thallium studies were performed early after myocardial infarction at a mean of 4.6 days (range 3 to 11) in 50 patients. The time from the onset of chest pain to the administration of thrombolytic therapy was 2.6 hours (range 0.5 to 5.5). Q wave myocardial infarction was evident in 46 patients; four patients had a non-Q wave infarction (anterior infarction in 31 patients and inferior infarction in 19 patients). The serum mean peak creatinine kinase was 1503 IU/L (range 127 to 6500). Coronary angiography was performed in all patients at a mean of 3.1 days (range 2 to 10) and revealed the infarct-related vessel to be patent in 36 patients (72%). The ejection fraction was 48% (range 26% to 67%). After dipyridamole administration, 13 patients (26%) developed angina that was easily reversed with the administration of intravenous aminophylline. Systolic blood pressure decreased from 122 to 115 mm Hg (p less than 0.05) and the heart rate increased from 76 to 85 beats/min (p less than 0.05). None of the patients had significant hypotension, arrhythmias, or evidence of infarct extension. Perfusion abnormalities were present on the initial thallium images in 48 patients. Redistribution suggestive of ischemia was present in 36 patients (72%). Ischemia confined to the vascular distribution of the infarct vessel was evident in 22 patients. Seven patients had ischemia in the infarct zone as well as in a remote myocardial segment. Thus 29 patients (58%) had ischemia in the distribution of the infarct vessel. Ischemia in the infarct zone was evident in 19 of 36 patients (53%) with open infarct vessels and in 10 of 14 patients (71%) with occluded infarct vessels. In conclusion, thallium-201 single photon emission computed tomography using oral dipyridamole was safely performed in patients with recent myocardial infarctions who receive thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Confocal fluorescence microscopy with the tandem scanning light microscope.

Applications of the tandem scanning confocal microscope (TSM) to fluorescence microscopy and its ability to resolve fluorescent biological structures are described. The TSM, in conjunction with a cooled charge-coupled device (cooled CCD) and conventional epifluorescence light source and filter sets, provided high-resolution, confocal data, so that different fluorescent cellular components were distinguished in three dimensions within the same cell. One of the unique features of the TSM is the ability to image fluorochromes excited by ultraviolet light (e.g. Hoechst, DAPI) in addition to fluorescein and rhodamine. Since the illumination is dim, photobleaching is insignificant and prolonged viewing of living specimens is possible. Series of optical sections taken in the Z-axis with the TSM were reproduced as stereo images and three-dimensional reconstructions. These data show that the TSM is potentially a powerful tool in fluorescence microscopy for determining three-dimensional relationships of complex structures within cells labeled with multiple fluorochromes.

Animals↗

PubMed1986

Prediction of ovulation with basal body temperature.

Basal body temperature (BBT) is used extensively to monitor ovulation in the treatment of infertility. There are well-defined methods of interpreting the BBT graph retrospectively that identify a presumptive day of ovulation. The prediction of ovulation through utilization of the BBT graph (strictly concurrent interpretation) is adversely influenced by temperature fluctuation and cycle length variability. The BBT graph can be very useful when its interpretation is well defined and its limitations understood.

Body Temperature↗

PubMed1985

Limit setting on drug abuse in methadone maintenance patients.

In this prospective study the authors examined the effects of setting limits on continued drug abuse in patients receiving methadone maintenance. Subjects were randomly assigned either to structured treatment (drug use exceeding set limits resulted in methadone withdrawal) or to unstructured treatment (no consequences attended continued drug use). The structured treatment resulted in significantly less drug use and greater retention in the program. The authors conclude that these results confirm the importance of external structure in the treatment of addiction-related psychopathology.

Female↗

PubMed1985

Indications for bone marrow examination.

Explore the source record for details and available documents.

Bone Marrow Examination↗

PubMed1983

A comparison of methods to interpret the basal body temperature graph.

Specific criteria are given for several methods of determining the basal body temperature shift. The specific criteria selected have been coded for a uniform interpretation by computer, and interpretations have been compared for 8496 charts. Our results indicate that the method that defines the temperature shift as 0.3 degrees F or more above the running low average for at least 3 consecutive days provides the best concurrent chart interpretation method. A method that creates a smoothed curve that transects the average of all temperatures on a completed graph provides a good retrospective method for identifying the temperature shift. Both the temperature averaging technique and curve smoothing technique identified a temperature shift in more than 95% of the charts with complete temperature readings.

Adolescent↗

PubMed1982

Relationship between lesion formation and permeability of rat gastric mucosa to H+ and other cations.

The relationship between lesion formation and ionic permeability has been investigated in rat gastric mucosa in vivo. Changes in these parameters were measured in the mucosa treated topically with prostaglandins E2 and A2 and/or aspirin. Particular attention was paid to the net flux of H+ ions across the gastric mucosa. The effect of aspirin concentrations of 5 mM, 20 mM and '40 mM' (the latter, a suspension in a saturated solution) was investigated. Aspirin concentrations of 20 mM and '40 mM' produced a marked increase in lesion formation and increased the net mucosal to serosal flux of H+ ions. Aspirin 5 mM produced a significant increase in lesion formation but did not cause a significant change in net H+ ion flux. This result suggests that aspirin can have a direct irritant effect on the gastric mucosa and that the back diffusion of H+ ions is not a pre-requisite for the development of overt mucosal ulceration. The effect of topically applied prostaglandin E2 (PGE2) on aspirin-induced gastric mucosal damage was investigated. Concentrations of PGE2 of 10(-5) M and 10(-4) M ameliorated aspirin-induced damage, but these changes were not necessarily accompanied by a significant reduction in net H+ ion flux. Again, this result is not consistent with a direct relationship between lesion formation and mucosal permeability to H+ ions. Since PGA2 did not ameliorate aspirin-induced mucosal damage, the protective effect of PGE2 could not be attributed to its conversion to PGA2 in the acidic environment of the gastric lumen. 5 Changes in gastric mucosal potential difference (p.d.) and net fluxes of Na+ and K+ ions may occur without a concomitant change in the permeability of the gastric mucosa to acid back-diffusion. Thus, the assumption cannot be made that a change in the permeability of the gastric mucosa to one particular ion reflects a general increase in ionic permeability.

Animals↗

PubMed1979