The daily intraperitoneal injection to rats of doses of metrazol (30 mg/Kg), strychnin sulfate (1 mg/Kg) or picrotoxin (1.2 mg/Kg) that were initially subconvulsant, caused after a number of days which varied with the drug, clonic convulsions in a high percentage of the animals. However, after 18 daily injections of saline there was a similar increase of seizure susceptibility to the 3 drugs. The daily handling of rats as for injection, either followed or not by actual abdominal pricking (blank injection), had a similar though less pronounced effect. In animals that were housed in the same room where the others were tested, but which were not handled, the above mentioned doses of metrazol, strychnine and picrotoxin had no convulsant effect. These results indicate that the procedure of submitting rats to daily intraperitoneal injections is not as unconsequential as is usually thought to be, and that it may induce neurological changes.

Animals↗

PubMedDate not supplied

Magnetic resonance findings in 92 acoustic neuromas.

A retrospective analysis of the MR findings in 92 cases of acoustic neuromas is presented. The method of examination included in all cases intravenous injection of Gadolinium (Gd-DTPA or DOTA) with realization of sections in the axial and coronal planes. In 21 cases native MR studies were performed in the axial plane, before Gadolinium injection, with T1WI (n = 21), and T2WI (n = 6) images. Tumors were strictly intracanalar in 19 cases (20.7%), only localized in the cerebellopontine angle (CPA) in 5 cases (5.4%), and in 68 cases (73.9%) the tumors had intra- and extracanalar components. In this last group of lesions, 63.2% completely filled the internal auditory canal (IAC), and 36.8% occupied the internal portion of the IAC. In most cases (85.3%) the mean diameter of the CPA component was less than or equal to 2.5 cm. Lesions were more frequently homogeneous (58.8%) after Gd i.v.-enhancement. Heterogeneity was noted mainly in large lesions (greater than 2.5 cm: 100%). In all cases but one, the tumors were round, or oval-shaped, well-delineated, and did not present significant contact with the petrous bone. In 80.9% of CPA lesions, the center of the tumor was posteriorly excentered in relation to the internal auditory canal, whereas it was centered in 16.2% of cases. Widening of the IAC was observed in 51.1% of cases. In 45.2% of tumors of the CPA, smoothing of the posterior edge of the porus was visible.

Adolescent↗

PubMedDate not supplied

Current progress in the development of a totally implantable Gyro centrifugal artificial heart.

A totally implantable centrifugal artificial heart has been developed using a miniaturized pivot bearing supported centrifugal pump (Gyro PI pump). The authors report current progress in its development. The Gyro PI-601 has a priming volume of 20 ml, weighs 100 g, has a height of 60 mm, and has a diameter of 65 mm. This pump can provide 8 L/min against 150 mmHg at 2,250 rpm. It is driven by an miniaturized DC brushless motor with the coils fixed in a plastic mold that is waterproof and made of titanium (weight, 204 g; height, 18 mm; diameter, 65 mm). In this centrifugal artificial heart, two Gyro PI pumps are implanted independently to replace cardiac function without resecting the native heart. Its anatomic and surgical feasibility were confirmed experimentally. The Gyro PI-601 was implanted as a right or left ventricular assist device in the preperitoneal space of five calves. All five tests proceeded without any thromboembolic symptoms. One of five tests was extended more than 1 month to confirm the long-term feasibility of the Gyro PI-601 pump system. Based on the satisfactory results of the in vivo tests, the material conversion of the Gyro PI from polycarbonate to titanium alloy (Ti-6A1-4V) was undertaken to improve its biocompatibility for long-term implantation.

Alloys↗