Traumatic lesions of the corpus callosum

We investigated the mechanism of damage to the corpus callosum in a study of 46 brains obtained at the autopsies of patients with head injuries. After correlating the gross findings with the site of impact on the head, we think that such lesions in the corpus callosum are caused by stretching of callosal fibers and/or shearing forces in cases in which lateral movement or twisting of the brain occurs. This mechanism of the dynamic development of callosal injuries is also supported by the retraction bulb formation of axons found histologically in the corpus callosum.

Insulin release and metabolism of calcium, adenine and adenosine 3',5'-cyclic monophosphate

In order to assess further the mechanisms involved in insulin release, we prelabeled rat pancreatic islets of Langerhans by incubating either 45Ca or [2-3H]adenine. When prelabeled islets were perfused with a glucose-free medium (the experiment with 45Ca) and a medium containing 2.8 mM glucose (the experiment with [2-3H]adenine) respectively, a constant rate of efflux of the radioactivity was established by 30 min in each case. D-Glucose at 16.7 mM concentration elicited a rapid efflux of 45Ca and [2-3H]adenine derivatives ([3H]Ad) within 4 to 6 min after commencing the step-wise stimulation by glucose, concomitantly with insulin release. However, L-glucose and D-galactose littel stimulated both 45Ca and [3H]Ad release. Lanthanum chloride caused a burst peak of 45Ca release in the absence of glucose. A rapid efflux of 45Ca was caused by beta-D-glucose and D-glyceraldehyde to much lesser extent than by alpha-D-glucose. The slowly rising concentration of glucose at 0.1 mM/min of gradient level failed to elicit any rapid efflux of 45Ca or [3H]Ad, although insulin release occurred in accordance with an increase in glucose concentration. Even when the gradient of glucose concentration was raised to 0.7 mM/min, glucose failed to stimulate an efflux of [3H]Ad but the subsequent stimulation by 16.7 mM glucose caused a rapid efflux of [3H]Ad concomitantly with the release of insulin. No rapid efflux of 45Ca was observed under a slow-rise glucose stimulation until the gradient level of the glucose concentration was raised to 6.7 mM. Analysis of distribution of the radioactive adenine derivatives after incubation showed that the adenosine fraction had the highest radioactivity in the medium followed by the ATP, adenine and cAMP fraction in that order, and the ATP fraction had the highest radioactivity in the islet. The ratio of radioactivity in the cAMP fraction in the medium to the total count was the highest among all. On the basis of these results, it was suggested that the discharge of [3H]Ad and 45Ca might occur with the alteration of the membrane permeability induced by a rapid change of the glucose concentration, and that their discharge might perhaps link to the glucoreceptor mechanism directly controlling insulin release.

A case of rectal carcinoma concomitant with Pagetoid lesion in the perianal region--histopathological and electron microscopic observations--

A case of extramammary Paget's disease of the perianal area adjacent to a mucinous adenocarcinoma of the rectum is presented. The histopathological examination of the case revealed that within the epidermis adjacent to the invading rectal cancer nest, the formation of glandular structures can be observed occasionally, around which so-called Paget's cells are noted to be scattered and further many points of similarity between cancer cell and Paget's cell are proved by electron microscope. Perianal skin lesion looking like Paget's disease is proved to be due to intraepidermal spread of the rectal carcinoma. Referring to the literature, this is the first report to our knowledge, to elucidate the histogenesis of perianal extramammary Paget's disease associated with a rectal carcinoma using the electron microscopy.

Sensitized effect of prestimulation on insulin release from the perifused rat islets with a slow-rise glucose stimulation

The sensitized effect of prestimulation with 16.7 mM glucose on insulin release with a slow-rise glucose stimulation from the perifused rat islets of Langerhans was studied, together with the kinetic analysis of insulin release, and the interrelationship between the prestimulation time and the maximal rate of insulin release. All dose-response relationships which were derived from the dynamics of insulin release from islets prestimulated over various time periods within 60 min, showed sigmoidal profiles. Kinetic analyses were performed with Lineweaver-Burk's and Hill's equations. The 30-min prestimulation significantly reduced Hill's constant (n) from 6.2 +/- 0.7 of the control to 3.7 +/- 0.6 (p less than 0.05) and also enhanced the logarithmic equilibrium constant (log K) from -5.4 +/- 0.6 mM-n to -3.7 +/- 0.6 mM-n (p less than 0.05). However, the Km value was almost the same as that of the control (7.3 +/- 0.5 mM). On the other hand, the 60-min prestimulation remarkably diminished the Km value and the maximal rate of insulin release to 5.3 +/- 0.4 mM (p less than 0.05) and 0.6 +/- 0.08 muU/ml/islet/min (p less than 0.005), respectively. The maximal rate of insulin release linearly increased in proportion to the prestimulation time within 30 min. In conclusion, these results suggested that there would be some regularity depending on the prestimulation time in the process of transmission of the insulin-releasing signal in the pancreatic B cell and the accumulation of insulin into the provisional pool such as the labile insulin.