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Biomedical subjects

L A Perez

Publications and source records attributed to L A Perez.

14 recordsLinked to original sources
PubMed1988

Central oxotremorine antagonist properties of pirenzepine.

Pirenzepine, the prototype M1 muscarinic receptor antagonist, is an important compound for investigating the functional significance of M1 receptors at the integrated level of behavior but may have limitations imposed by its physical chemistry. Like the nonselective antagonist methylatropine, pirenzepine is highly hydrophilic and crosses the blood-brain-barrier with difficulty. We compared methylatropine with pirenzepine, given intraperitonealy, as antagonists of the behavioral effects of peripheral or central muscarinic activation. Lever-press responses of male Sprague-Dawley rats were maintained under a schedule requiring 10 responses for each food delivery. Administration of oxotremorine or the quaternary analog oxotremorine-M decreased rates of responding by at least 90%. Both methylatropine and pirenzepine antagonized the behavioral effects of oxotremorine-M; maximum reversal was 70%. Although methylatropine was about 30 times more potent than pirenzepine as an antagonist of the peripheral muscarinic activity of oxotremorine-M, it was inactive as an antagonist of oxotremorine when given in doses up to 153 mumol/kg. Pirenzepine, however, reversed oxotremorine-induced behavioral effects, with a maximum antagonism of 50%. These results suggest that pirenzepine interacts with central muscarinic receptors when administered systemically without producing marked behavioral effects of its own. Systemically administered pirenzepine may thus be a useful tool in further investigations of the relevance of M1 receptors to behavioral function.

Animals↗
PubMed1979

The value of the negative radionuclide scrotal scan in the management of the acutely inflamed scrotum in children.

Torsion of the testis remains a clinical diagnosis and confirmatory testing is not required when the classic signs and symptoms are present. Conflicting laboratory data or adjunctive diagnostic studies should not dissuade the surgeon from exploration when the clinical index of suspicion is high. In those patients having equivocal clinical findings when the diagnosis of torsion is not clear-cut radionuclide scrotal imaging may be useful. In this series a negative scrotal scan at the time of acute scrotal pain did predict reliably the diagnosis of non-torsion, suggesting that in the appropriate clinical setting scrotal imaging is useful in avoiding surgical exploration.

Adolescent↗
PubMed1978

Is the anterior bone scan necessary in the diagnosis of osseous metastases?

Bone imaging studies of 1650 patients with known or strongly suspected extraosseous malignancies were reviewed to determine whether a completely negative posterior view was sufficient to exclude metastatic disease. Of 708 negative posterior images, 27 (3.4%) were positive for metastasis on anterior views. All of the anterior lesions were in the sternium, sternoclavicular joints and first four ribs. When the posterior view is positive, further views may be unnecessary. Negative or equivocal posterior images necessitate anterior views of the thoracic cage.

Bone Neoplasms↗
PubMed1976

Clinical experience with technetium-99m stannous polyphosphate for myocardial imaging.

Myocardial imaging with technetium-99m stannous polyphosphate was performed on 46 patients. Eleven patients had no cardiac disease, 22 had acute myocardial infarction, and 13 had stable arteriosclerotic heart disease. Distinct patterns of myocardial activity were noted: (1) the patients with no obvious cardiac disease showed no cardiac activity; (2) stable arteriosclerotic heart disease showed faint, ill-defined cardiac activity, primarily in the anterior or inferior aspect of the left ventricle; (3) acute myocardial infarction showed intense, focal, well-defined activity, with a shape that characterized the location of the infarct.

Acute Disease↗
PubMed1976

Cervical venous reflux in dynamic brain scintigraphy.

Cervical venous reflux, shown by dynamic brain scintigraphy, was investigated through three avenues of approach: (A) by reviewing 371 randomly chosen routine dynamic intracerebral bloodflow studies to estimate its incidence; (B) by correlative positive-contrast superior venacavography in patients with characteristic cervical venous reflux; and (C) by performing dynamic brain scintigraphy while utilizing various positional and physiologic maneuvers to attempt to produce cervical venous reflux in patients who did not exhibit this phenomenon on earlier examination. Although any obstruction of the superior vena cava or a properly timed Valsalva maneuver in selected patients can produce the scintigraphic picture of cervical venous reflux, in most cases it is a normal phenomenon due to incompetent or absent cervical venous valves.

Aged↗
PubMed1976

Localization of myocardial disorders other than infarction with 99mTc-labeled phosphate agents.

Myocardial studies with 99mTc-labeled phosphate agents were obtained in 20 patients without demonstrable cardiovascular disease, 24 patients with unstable arteriosclerotic heart disease (ASHD) without acute infarction, and six patients with myocardiopathy. The patients without cardiovascular disease showed no localization or tracer; the patients with unstable ASHD and without acute infarction showed nonfocal ill-defined accumulation of tracer; and the patients with myocardiopathy showed diffuse accummulation of tracer throughout the confines of an enlarged cardiac outline. Careful evaluation of both the distribution and intensity of the activity, in conjunction with the clinical picture, allows differentiation among these disease processes. Since ischemic areas around infarcted tissue may show increased activity, the value of this technique for sizing acute myocardial infarction may be limited.

Adult↗
PubMed1975

Dosimetry of portable image intensifiers in pacemaker insertions.

With the increased utilization of portable image intensifiers for pacemaker insertions, an investigation of the radiation hazards to operative personnel was undertaken. The personnel were tested first utilizing a Rando phantom and later during actual pacemaker insertions. Studies of medical personnel show the critical organs to be the thyroid (approximately 15mR per procedure) and the lens of the eye (approximately 13mR per procedure). While the MPD/week was not exceeded, the radiation dosage was substantial and could increase under operating conditions other than those measured. Recommendations to insure safer operation of this equipment are presented.

Fluoroscopy↗
PubMed1975

Experience with modified remotely controlled fluoroscopic equipment for gastrointestinal examination in debilitated patients.

The concept and realization of a highly automated remotely controlled fluoroscopic system, applicable to the examination of debilitated or uncooperative patients, have been described. The addition of a rotating cradle, remotely controlled barium administration, magazine-fed roll film camera, remotely inflated paddle for prone-pressure spot filming, and a vacuum restraining device have been described for the examination of uncooperative as well as cooperative patients. These patients can be examined with as high a degree of sophistication and automation as is now available. Future developments in this area may lie in the realm of multitable remotely controlled fluoroscopic rooms, operation of the above equipment by a super technologist, programmed gastrointestinal examinations utilizing the above equipment and automated programming, and teleremote controlled fluoroscopy from a centralized location with coaxial cable or microwave transmission.

Fluoroscopy↗