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Biomedical subjects

I Mena

Publications and source records attributed to I Mena.

At least 109 records · Page 6Linked to original sources
PubMed1983

Gold-195m, an ultra-short-lived generator-produced radionuclide: clinical application in sequential first pass ventriculography.

Gold 195m (Au-195m) has a half-life of 30.5 sec and can be produced at the bedside from the parent mercury-195m (T 1/2 = 41.6 hr). The generator produced sterile pyrogen-free Au-195m with mercury breakthrough of 0.75 +/- 0.09 (s.e.m.) muCi per mCi of Au-195m. Approximately 20 to 25 mCi of Au-195m was produced per elution from a generator containing 155 mCi of Hg-195m. We compared first-pass resting Tc-99m angiograms with Au-195m angiograms in 28 patients. The correlation coefficient between the two studies was 0.92 over an ejection-fraction range from 0.22 to 0.83. In addition, we tested the reproducibility of Au-195m first-pass angiograms by performing two studies 3 min apart. In 25 patients with ejection fractions ranging from 0.20 to 0.78, the correlation coefficient between such pairs was 0.93. The nuclide is reliably and reproducibly produced, and its short half-life allows the performance of background-free sequential first-transit studies with unusually low radiation exposure to the patient.

Gold Radioisotopes↗
PubMed1979

Effects of maximal exercise stress on left ventricular function in patients with coronary artery disease using first pass radionuclide angiocardiography: a rapid, noninvasive technique for determining ejection fraction and segmental wall motion.

Angiographically determined changes in segmental wall motion (SWM) and ejection fraction (EF) are sensitive indices of left ventricular (LV) function. To compare the effects of exercise on LV function, first pass radionuclide angiocardiography was used before and during maximal upright bicycle stress in patients with nonsignificantly stenosed coronary arteries, and in those with greater than 75% stenosis. Gamma camera acquisitions were made in the 30 degree RAO projection using a 20 mCi I.V. bolus of 99mTc-pertechnetate. In the control group (seven normals, one nonsignificant (CAD) the EF significantly increased between rest and exercise (0.65 +/- 0.03 to 0.81 +/- 0.03 (mean +/- SEM), p less than 0.005). In this group SWM measured over the two anterior and two inferoposterior segments uniformly increased. In the 11 patients with a history of angina and significant coronary artery obstruction, the EF did not change in three and significantly decreased in the remaining eight (0.57 +/- 0.04 to 0.45 +/- 0.03, p less than 0.005). In all 11 patients SWM either decreased or did not increase in the areas supplied by the significantly stenosed coronary arteries. Upright maximal stress angiocardiography appears to be well-suited for diagnosing ischemic heart disease and localizing the area of ischemic dysfunction.

Adult↗
PubMed1978

Disphosphonate dynamic imaging of experimental bone grafts and soft tissue injury. Radionuclide bone imaging.

Bone imaging provides two significant advantages over previously available methods for assessing bone processes. First, as scanning is non-invasive, it offers the operator the ability to sequentially follow any area of bone without altering it as would a biopsy. The second advantage is the ability of bone imaging to provide current information about the bone being scanned rather than having to deal with the delay that is inherent in conventional radiography. Recent developments in radiopharmaceuticals and instrumentation have made bone imaging a potentially practical clinical tool for the detection and assessment of benign as well as malignant processes affecting bone. This paper presents the results of the use of technetium 99m diphosphonate bone imaging in experimental canine mandibular autografts and surgical soft tissue injury. The implication of these results for the clinical situation will be discussed.

Animals↗
PubMed1978

Evaluation of left ventricular function (ejection fraction and segmental wall motion) by single pass radioisotope angiography.

Changes in ejection fraction (EF) and segmental wall motion (SWM) have been shown to be sensitive indicators of left ventricular (LV) function. This information is only obtainable by contrast angiography or gated blood pool scans. Gated studies assume a fixed geometry for the LV for EF determinations, are lengthy and limited primarily to the LAO projection. We correlated contrast and Tc-99m pertechnetate angiograms by singl pass radioisotope angiography (immediately preceding the contrast study) in 12 patients. EF was calculated from the LV time/activity curve and values ranged from .21 to .72. Angiographic correlation yielded r = 0.97. Regional LV wall motion was evaluated by dividing a summated cardiac cycle into 16 frames and dynamically and sequentially displaying these frames. Regional wall motion evaluation of four LV quadrants correlated well with angiography (r = 0.97). For quantitation these images were divided into four anterior and four inferior segments and the areas of respective segments were compared and expressed as a shortening fraction. SWM compared favorably with angiographic determinations (r ranged from 0.70 to 0.99). Thus, single pass radioisotopic determinations of EF and SWM in the RAO projection correlated well with the angiographic values and provide essential quantitative information of LV function otherwise unobtainable at the bedside.

Adult↗
PubMed1977

Gallium 67 citrate scanning in the diagnosis of intraabdominal abscess.

Fifty-one consecutive gallium scans in fifty patients with suspected intraabdominal abscess are reviewed. There were twelve true-positive, seven false-positive, twenty-nine true-negative, and two false-negative scans. Accumulation of gallium in the colon and in areas of healing and repair caused soem interpretive difficulty. Despite a significant number of false-positive results, we believe that gallium scanning is a valuable diagnostic tool. Careful attention to technic and cautious interpretation should significantly reduce false-positive and false-negative scans.

Abdomen↗
PubMed1977

The significance of calcific valvular heart disease in Tc-99m pyrophosphate myocardial infarction scanning: radiographic, scintigraphic, and pathological correlation.

Technetium-99m pyrophosphate (PPi) is currently considered the best scanning agent for the diagnosis of acute myocardial infarction. False-positive scans have been reported in association with unstable angina, alcoholic cardiomyopathy, and ventricular aneurysms. In this study, 86% of patients (12/14) with either calcific aortic or mitral valvular heart disease had positive PPi cardiac scintiscans and the location of the PPi uptake was limited to the calcific valve in all (9/9) of the patients who underwent valve replacement surgery. Six patients with valvular disease without radiologic evidence of calcium had negative PPi heart images. Three of these patients had surgical valve replacement, and in none was there increased uptake in the resected valve. Seventy-five percent of the patients with calcified aortic valves had localization of the PPi activity to the area of the aortic valve, whereas 50% of the patients with calcified mitral valves showed a diffuse pattern of uptake on the cardiac image. In vitro demonstration of increased radioactivity in surgically removed cardiac valves warrants the conclusion that Tc-99m PPi is taken up by calcified heart valves. We conclude that while PPi heart scanning is a sensitive indicator of acute myocardial infarction, false-positive scans can occur in the presence of calcific valvular disease, due to localization of PPi in the calcified portion of the valve.

Adolescent↗
PubMed1976

Experience with jejunoileal bypass for obesity.

Fifty-eight patients less than 30 years old but who are more than 300 pounds in weight were considered for investigation of jejunoileal bypass. Thirty patients had operations, and the functioning bypass included 40 centimeters of jejunum and 10 centimeters of ileum. In 14 patients, intestinal continuity was restored by either end-to-end or end-to-side anastomosis according to random choice, and in 16 patients, end-to-end anastomoses were used. At present, the follow-up period is one to four years, and the weight loss, so far, has not been significantly related to the type of reconstruction used. Weight loss correlated possitively with the preoperative weights up to one year after operation. Also, weight loss correlated positively with the total measured length of the small intestine during the first six postoperative months, but this correlation currently is showing a trend toward negativity. Food intake decreased by 2,682+/-690 calories per day at six months after operation as a result of the bypass. Chronic acidosis was common. Results of an endocrine evaluation revealed an unexpected significant decrease in parathormone levels within the normal range. A new complication, colonic pseudo-obstruction, has occurred one year or more after operation in five patients or 17 per cent of our group. This complication is related to the intestinal anaerobic flora in proximity of the defunctionalized limb; its symptoms and signs can be alleviated by giving antibiotics or Lactobacillus to change the intestinal flora. Although 90 per cent of our patients are pleased with their progress and the results of routine evaluation corroborate their satisfaction, detailed analysis of the research data available to us revealed that only 43 per cent have had beneficial effects from a jejunoileal bypass without any of the serious sequelae. We consider jejunoileal bypass for obesity justified when carried out by interdisciplinary groups dedicated to the long term follow-up study of the patient and periodic reporting of the results. The long term future for the operation is, as yet, not completely understood, and when the conditions we have recommended are not present, we cannot currently endorse the operation.

Adult↗
PubMed1976

[Sleep stages and growth hormone in manganese poisoning. Effects of L dopa].

Sleep characteristics are studied in 7 patients with sequelae of manganese intoxication and in 8 controls. A reduction in the length of the REM stage was observed, which could be prolonged by L Dopa administration, but without achieving values comparable to the controls. No changes were noted in the non-REM stage of sleep. These results are similar to the ones obtained in Parkinson's disease, suggesting clinical and probably biochemical similarities between the 2 conditions. The blood concentrations of growth hormone during sleep in the manganic patients was lower than in the control group, and no significant variations were noted after L Dopa administration.

Adult↗
PubMed1975

Diphenylhydantoin. Blocking of levodopa effects.

Diphenylhydantoin (DPH) diminished the therapeutic effects of levodopa both in patients with parkinsonism and in patients with chronic manganese poisoning, as well as the levodopa-dependent dyskinesia for which the former were selected. In patients with Huntington chorea, it enhanced chorea and mental agitation and, thus, failed to conform with the postulated pharmacological reciprocity between Parkinson disease and Huntington chorea. These findings are in agreement with experiments done in animals in which DPH blocked a neuronal response to dopamine.

Adult↗
PubMed1975

Human CNS perfusion scanning with 123I-iodoantipyrine.

Regional perfusion scanning of the central nervous system requires lipophilic radionuclides that rapidly penetrate the intact blood brain barrier. The first compound of this type to be developed for human use is 123I-iodoantipyrine. 123I-iodoantipyrine rapidly crosses the blood brain barrier and is flow-limited in its delivery to the brain. This makes possible the CNS perfusion scanning of the human brain, thereby showing regional distribution of microcirculatory blood flow.

Animals↗