Characteristics of learning and memory impairment induced by delta9-tetrahydrocannabinol in rats

We investigated the characteristics of delta9-tetrahydrocannabinol (THC)-induced impairment of learning and memory using an 8-arm radial maze task, a water maze, a visual discrimination task with 2 figures and a passive avoidance test in rats. THC (6 mg/kg, i.p.) impaired spatial memory in the standard task of the 8-arm radial maze. THC (4-6 mg/kg, i.p.) selectively impaired working memory in a reference and working memory task of the 8-arm radial maze. Even at a dose of 10 mg/kg, THC did not impair spatial memory in the water maze. In addition, THC at a dose of 6 mg/kg, which had inhibitory effects in the 8-arm radial maze, did not affect performance in the visual discrimination task. These results indicate that at low doses (2-6 mg/kg), THC may not produce visual function abnormalities. THC impaired retrieval (6 mg/kg, i.p.) as well as acquisition (10 mg/kg, i.p.) in the passive avoidance test. The consolidation process was also impaired by i.c.v. injection (100 microg), but not i.p. injection (6-10 mg/kg) of THC. These results suggest that THC-induced impairment of spatial memory is based on the selective impairment of working memory through its effects on acquisition and retrieval processes.     

Endomyocardial biopsy approach to patients with ventricular tachycardia with special reference to arrhythmogenic right ventricular dysplasia

Right ventricular endomyocardial biopsies were performed in patients with repetitive ventricular tachycardia (VT; 8 patients) or ventricular premature beats (1 patient) which showed left bundle branch block morphology in electrocardiograms. These 9 male patients ranging in age from 21-55 years (mean 37.7 years) revealed enlargement and/or asynergy of the right ventricle in the ventriculogram. Randomly selected biopsied patients with dilated cardiomyopathy (DCM; 18 patients) and chronic right ventricular overloading (14 patients) who did not show the above-described arrhythmias served as controls. A histopathological analysis revealed advanced myocardial interstitial fibrosis associated with an increase in fatty tissue in 8 of the 9 patients (89%). Moreover, advanced hypertrophy of myocytes (grade 2 or more of our criteria), disarrangement of muscle bundles and endocardial thickening were prominent with incidences of 75%, 75% and 78%, respectively. Incidence of all findings was more pronounced in the ARVD group. Suggestiveness of post-myocarditic change in the biopsied specimen was high in 1 patient, showing a lower incidence (12%) than the DCM group (17%). From these results, we can conclude that different etiological factors may be the bases of these pathological changes. We believe that the presence of a large amount of fatty tissue within the myocardial tissue is an important element in the etiology of ventricular arrhythmias as it has also been recognized in patients with non-ARVD idiopathic ventricular tachycardia in our biopsy series.     

Natural history of subarterial infundibular ventricular septal defect

Development of aortic valvular deformities was studied retrospectively in 395 inpatients with subarterial infundibular ventricular septal defect (siVSD). Aortic valvular deformities included prolapse into siVSD without aortic regurgitation (77 patients), prolapse and aortic regurgitation (95 patients), and aneurysm of the sinus of Valsalva (36 patients). No aortic valvular deformity was found in 187 patients, and 111 of these 187 patients had associated pulmonary hypertension. Prolapse and regurgitation of the aortic valve developed most frequently at the age 5 to 8 years. Aneurysm of the sinus of Valsalva was not found before the age of 10 years but began to develop during the teens and was diagnosed most frequently in the twenties. Patients with pulmonary hypertension did not develop aortic valvular deformities except in one instance. All inpatients with siVSD and without pulmonary hypertension over the age of 30 years had developed some aortic valvular deformities.     

Normalized natural killer (NK) cell activity in long-term remission of acute leukaemia

NK cell activity was studied in 28 cases of acute leukaemia in remission. It was found that patients in long-term remission for 5 years or more had normal NK cell activity but those in remission for less than 5 years had significantly lowered activity. This suggests that patients with acute leukaemia had not been constitutionally deficient in NK cell activity. Low activity was augmented but not fully restored by interferon pretreatment in vitro . Therefore, the low NK cell activity observed during remission is not solely attributable to inadequate secretion of interferon in the host. It is suggested that the production of NK cells in bone marrow is impaired, or the function of NK cells is suppressed, by the leukaemia itself or by chemotherapeutic agents. Increased consumption of NK cells is also a possibility.     

Relationship between the thoracic asymmetry in standing position and the asymmetry of ankle moment in the frontal plane during gait

[Purpose] We aimed to investigate the relationship of thoracic asymmetry in standing position with asymmetry of the internal ankle moment in the frontal plane during gait. [Participants and Methods] The following measurements were recorded in 22 healthy adult males using a 3D motion analyzer and force plates: thoracic lateral deviation, asymmetrical ratios of the upper and lower thoracic shape, internal ankle moment in the frontal plane, mediolateral deviations of the center of mass and center of pressure. [Results] In the standing position, the thorax was deviated to the left relative to the pelvis, and the upper and lower thoracic shapes were asymmetrical. During gait, significant lateralities were observed in the internal ankle moment in the frontal plane, mediolateral deviations of the center of mass and the center of pressure. Significant positive correlations were observed between the asymmetrical ratio of the lower thoracic shape and both the asymmetry of the internal ankle moment in the frontal plane and the mediolateral deviation of the center of pressure. [Conclusion] These results suggest that thoracic asymmetry is associated with mediolateral control of the ankle during gait.