Intracellular Abeta is increased by okadaic acid exposure in transfected neuronal and non-neuronal cell lines.

Intracellular Abeta was examined in both a neuronal cell line (B103) expressing human APP with Swedish mutation and a non-neuronal cell line (Chinese hamster ovary, CHO) expressing wild human APP. Exposure of the APP695sw-transfected B103 cells to okadaic acid for 3 h, Abeta immunostaining was enhanced, as demonstrated by two independent anti-Abeta antibodies. The confocal microscopic study revealed that the immunoreactivity of Abeta was mainly colocalized with a Golgi marker and partially with an ER marker. Quantitative analyses, using Abeta sandwich ELISA, showed significantly increased intracellular Abeta. False positive detection of Abeta by antibody cross-reaction with APP was ruled out by extracting the fraction with formic acid and making it alkaline before subjecting it to ELISA. This procedure resulted in a fraction that contained little APP. Using CHO cells, OA treatment was also shown to be effective in increasing Abeta, as demonstrated by Western blot. The increased full-length APP and decreased APPC99 were also observed. This is the first study to demonstrate that OA treatment significantly increases intracellular Abeta.     

In vitro controllability of the MagScrew total artificial heart system

The purpose of this study was to evaluate the in vitro responses to preload and afterload of our total artificial heart (TAH), the MagScrew TAH. The TAH consists of two blood pumps and a control logic, developed at the Cleveland Clinic, OH, and the MagScrew actuator and its electronic control system, developed by Foster-Miller Technologies, Inc., Albany, NY. Tests were performed on a mock circulatory loop, using water as a test fluid. Preload sensitivity of the Mag-Screw TAH demonstrated a Frank-Starling response to preload in automatic mode. A peak flow of 10 L/min was obtained, with a left atrial pressure of 13 mm Hg. The relationship between right atrial pressure and left atrial pressure was well balanced when tested with a left bronchial shunt flow of 5% and a range of pulmonary artery and aortic pressures. With respect to afterload response, the left pump showed a relatively low sensitivity, which allowed the pump to maintain perfusion over a wide range of aortic pressures. The right pump, on the other hand, was much more sensitive to pulmonary artery pressure, which provided a measure of protection against pulmonary congestion. The very effective physiologic response of the MagScrew TAH is believed to result from employment of a left master, alternating ejection control logic, high inherent sensitivity of the blood pumps to atrial pressure, a lower effective stroke volume for the right pump, and a scaling of right side motor ejection voltage to 80% of that used for the left side ejection.     

Development of a new calcium phosphate cement that contains sodium calcium phosphate

A cement powder consisting of sodium calcium phosphate, Na3Ca6(PO4)5, in addition to tetracalcium phosphate and beta-tricalcium phosphate was prepared by pulverizing blocks of 4 wt% sodium-, 11 wt% carbonate-containing apatite samples that were heated at 1700 degrees C for 5 h. When mixed with 30 wt% malic acid or citric acid at a powder liquid ratio of 3:1, the cement set in 3 or 7 min at room temperature with compressive strength being around 52 or 27 MPa. In HeLa-cell cultures, the cement mixed with malic acid was less cytotoxic than the cement mixed with citric acid, which was far less cytotoxic than a commercial carboxylate cement used as a negative control, suggesting malic acid to be superior to citric acid as a liquid in this regard. Similar findings were also obtained with osteoclasts, of which culture experiments clearly suggested that the number of osteoclasts on the cement mixed with malic acid was significantly greater than that on the cement mixed with citric acid. Since osteoclastic response to substrates could be used as a maker in evaluating their bioresorbability associated with osteoclasts, the above finding may suggest that the cement that is to be mixed with malic acid would be more useful as bone substitutes.     

Influence of internal and external donors on activity and stereospecificity of ziegler-natta catalysts

Three kinds of MgCl₂-supported TiCl₄ catalysts (ester-free, ethyl benzoate (EB, monoester) and dibutyl phthalate (DNBP, diester) as internal donors) were prepared. Polymerization of propylene was carried out using these catalysts with and without phenyltriethoxysilane (PTES) as an external donor. Significant differences were observed in the kinetic behavior of polymerization among ester-free, monoester, and diester systems. Addition of PTES, however, did not change the kinetic behavior. The polymers produced were separated into three fractions by extraction with boiling heptane and octane, and the molar mass distribution (MMD) curves were measured for these three fractions. The heptane-insoluble, isotactic polymer obtained in the absence of PTES was found to consist of two fractions, octane-soluble and -insoluble. The octane-soluble polymer having lower molar mass contained appreciable amounts of syndiotactic stereoblocks in the chains, whereas the octane-insoluble polymer did not contain such stereoblocks. Addition of PTES drastically increased the octane-insoluble fraction without changing the average molar mass. On the other hand, the MMD curve for the heptane-soluble, atactic polymer gradually shifted to the lower molar mass range with an increase in the concentration of PTES. From these results, the effects of internal and external donors on catalyst activity and stereospecificity were discussed putting emphasis on the differences between monoesters and diesters.     

Hepatic changes in the acute phase of streptozotocin (SZ)-induced diabetes in mice

We have reported the streptozotocin (SZ)-induced hepatic lesions in the subacute phase (4 to 12 weeks after the treatment), which are characterized by appearance of oncocytic hepatocytes, cytomegalic hepatocytes and bile duct hyperplasia. In this study, we focused on the acute phase (6 to 48 hours after the treatment) of the SZ-induced hepatic lesions of mice to clarify the onset of the hepatic alterations, especially before the induction of hyperglycemia. Livers were taken from 8-week-old Crj:CD-1 (ICR) male mice at 6,12, 24, 36 and 48 hours after the 200 mg/kg b.w. of SZ-injection. SZ-induced hyperglycemia was noted at 36 and 48 hours after the treatment, but the hepatic changes including lipid peroxidation, mitochondrial swelling, peroxisome proliferation and inhibition of hepatocyte proliferation occurred before the elevation of the serum glucose levels. The present findings indicate the direct effects of SZ on hepatocytes rather than the secondary effects of diabetes, and certain correlations between the hepatocytic changes in the acute phase and those in the subacute one. In addition, ulcer and submucosal edema of the gallbladder were observed at 36 or 48 hours after the SZ-treatment, which can be a novel finding in SZ-treated animal.     

Blood vascular architecture of the palatine tonsil in the musk shrew (Suncus murinus): scanning electron microscopic study of corrosion casts

The musk shrew, Suncus murinus, is one of the primitive mammals and has a pair of palatine tonsils. In the present study, we investigated the blood microvascular architecture of the tonsil in this animal by scanning electron microscopy of corrosion casts. The paranodular arterioles entered the lymph nodule to form a coarse capillary plexus within the nodule. Some of the arterioles reached the dome region to give rise to a fine meshwork of dome subepithelial capillaries. This dome subepithelial capillary network did not show any hairpin or switch-back patterns, as seen in human and rabbit tonsils. Both of the nodular and dome capillaries were drained into the postcapillary venules in the periphery of the nodular or the paranodular region. On the surface of these cast venules, oval-shaped indentations were seen corresponding to the luminal surface of the high endothelial venules. These venules were collected into the large vein at the bottom of the tonsil. The blood vascular architecture of the musk shrew tonsil is basically the same as those of other mucosa-associated lymphoid tissues in mammals.