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Biomedical subjects

F J Miranda

Publications and source records attributed to F J Miranda.

At least 73 records · Page 4Linked to original sources
PubMed1981

The diametral tensile strengths of various composite resins.

The products exhibiting the greatest tensile strength values were those systems which provided measuring devices enabling the dentist to more accurately control the amounts of material to be mixed. Statistical analysis supported this finding; the means of the powder/liquid and paste/liquid systems formed a group that was significantly different from the five paste/paste systems. This indicates that accurate measurement of components could represent one important factor in the ultimate strength of a composite resin. There was no apparent correlation between average density and mean diametral tensile strength for the seven systems compared in this study.

Chemical Phenomena↗
PubMed1976

Comparative stability of two removable die systems.

The comparative stability of two removable die systems was evaluated. Under controlled conditions, ten casts, each with two removable dies, were constructed for each system for a total of 20 casts and 40 removable dies. Base-line pre- and postsectioning measurements to within 0.0001 inch in horizontal and vertical planes were recorded and differences calculated. Each die was removed and re-placed 30 times prior to any postsectioning measurement. The results indicated small inconsistent horizontal deviations and consistent vertical deviations for both systems. The Pindex system deviations were slightly less than those of the Di-Lok system, although t test values preclude any conclusion of significance. The results of this investigation indicate the need for dentists and dental laboratory technicians to exercise care in the utilization of any removable die system so as to obtain optimum accuracy and stability in the relationships of the components of that system.

Dental Casting Technique↗
PubMed1976

Diagnosis and treatment of pulpal distress.

Both diagnosis and treatment of vital pulp tissues encompass some fairly comprehensive varieties of methods and materials. Diagnosis is arrived at in terms of probability. No one can be absolutely sure that the diagnosed degree of pulpal distress is in fact the actual state of affairs. Treatment, therefore, must be best be a probability also. There can be no guarantee that the treatment rendered will succeed in every instance. Any diagnosis and treatment of reversible pulpal distress is a gamble on the part of both practitioner and patient. However, utilization of every diagnostic means at his disposal, knowledge of the many treatment modalities available for use, and the ability to correlate both the diagnosis and treatment phases of a given case will result in a high probability of success. This is indeed rewarding to both the patient and the dentist.

Dental Cavity Lining↗
PubMedDate not supplied

Evidence of a direct constrictor action of MK-801 and its modulation by the endothelium in cerebral arteries.

The effects of MK-801 on the cerebral arteries and the possible involvement of the endothelium in such a response were examined using two experimental approaches: in vivo, by recording cerebral blood flow (CBF) in the unanesthetized goat, and in vitro, by recording isometric tension in goat and human cerebral arteries. Injection of increasing doses (3, 10, 30, and 100 micrograms) of MK-801 directly into the cerebroarterial supply elicited decreases in CBF and increases in cerebral vascular resistance (CVR; for the highest dose tested CBF decreased by 16 +/- 10% and CVR increased by 18 +/- 10%, p < 0.05). Administration of MK-801 as a single intravenous bolus (0.2 mg kg-1) reproduced that vasoconstrictor response (CBF decreased by 17 +/- 9% and CVR increased by 46 +/- 33%, p < 0.05), and it was followed by a phase of sustained tachycardia (26 +/- 15% increase in resting heart rate, p < 0.01) and hypertension (34 +/- 17% increase in resting mean arterial blood pressure, p < 0.05). In the in vitro experiments, addition of cumulative concentrations (10(-6) to 3 x 10(-4) M) of MK-801 elicited concentration-related contractions of goat and human cerebral arteries at both resting and active tone (10(-5) M prostaglandin F2 alpha).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Effects of calcium entry blockers on KCl- and 5-hydroxytryptamine-induced contractions of human umbilical arteries.

The effects of Ca2+ removal and of the calcium entry blockers, nicardipine and nifedipine, on contractions of isolated human umbilical arteries, elicited with KCl and 5-hydroxytryptamine, were investigated. Withdrawal of Ca2+ caused inhibition of both KCl and 5-hydroxytryptamine responses, but the maximum effect of KCl in Ca2(+)-free medium was recuperated by increasing the KCl concentration. The maximum effect of 5-hydroxytryptamine, however, was recuperated only when Ca2+ was restored to the medium. Consistently with an inhibition in Ca2(+)-free medium, calcium entry blockers produced a concentration-dependent relaxation of human umbilical artery strips precontracted with KCl and 5-hydroxytryptamine, and inhibited the concentration-dependent contraction elicited by these stimuli. Our results indicate that contractile responses of the human umbilical arteries are dependent on extracellular Ca2+ for both KCl and 5-hydroxytryptamine. Although Ca2+ entry was sensitive to both nicardipine and nifedipine, the differences between the effects of these dihydropyridines with the two experimental approaches we used were not always conclusive.

Calcium Channel Blockers↗
PubMedDate not supplied

Carcinosarcoma of the esophagus.

Two rare cases of carcinosarcoma of the esophagus are presented. In the first case the decision to operate was based on an initial diagnosis of leiomyosarcoma made by endoscopic biopsy. In the second, a diagnosis of carcinosarcoma was also obtained by endoscopic biopsy. The pathology is commented on. The authors discuss their opinion that carcinosarcoma of the esophagus constitutes a well defined anatomopathological entity.

Carcinosarcoma↗