A polyvinyl alcohol (PVA) hydrogel as a soft contact lens material

A transparent polyvinyl alcohol (PVA) hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water miscible organic solvent by cooling. The physical properties were evaluated in comparison with commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methyl methacrylate (MMA) and N-vinyl pyrrolidone (VP). The PVA hydrogel showed higher tensile strength and elongation at break than the other materials, while it had high water content and oxygen permeability the latter being comparable to those of PMMA/VP copolymers. The protein adsorption of the PVA hydrogel was much less than those of the other materials. The PVA hydrogel soft contact lenses were applied on rabbit eyes for 12 weeks. The influence on the cornea was studied by biomicroscopy, ultrasonic corneal pachymetry and histopathological examination. These examinations revealed no abnormal findings in the cornea. These results suggest that the PVA hydrogel may be promising as a new soft contact lens material.     

High Cell-Density Culture System of Hepatocytes Entrapped in a Three-Dimensional Hollow Fiber Module with Collagen Gel

Abstract: A compact three-dimensional (3D) module is needed for hepatocyte culture in order to develop an effective hybrid artificial liver system that can retain hepa-tocellular structure and differentiated functions. We treated the 3D module with collagen gel to entrap rat hepatocytes. This method yielded a high hepatocellular density (2 times 10⁷ cells/ml) over a period of 14 days and maintained the secretion of albumin and ureogenesis at the same level as the control monolayer method. The ammonia removal remained at 43% of the Day 0 value over 8 days of perfusion. Our data show that this approach may be useful for liver support therapy in an ex-tracorporeal circuit.     

Activity-dependent survival and enhanced turnover of calcium in cultured rat cerebellar granule neurons

Neurons survive when their activity is maintained. An influential hypothesis on the cellular mechanism underlying this phenomenon is that there is an appropriate range of intracellular Ca²⁺ concentration ([Ca²⁺]i) for survival. The rat cerebellar granule neuron in culture serves as the most often used model system for the analysis of activity-dependent survival, since it does not survive unless an excitant (KCl or glutamate) is added to the culture medium. Against the above-mentioned hypothesis, we found in our previous examination no difference between steady-state [Ca²⁺]i in granule neurons cultured under high KCl (i.e., survival) and low KCl (i.e., death) conditions. In this report, we present the quantitative background of unchanged [Ca²⁺]i between the two culture conditions. Influx of Ca²⁺ due predominantly to L-type voltage-dependent calcium channels was higher in high KCl cultures than in low KCl cultures. At the same time, efflux of Ca²⁺ due to the activity of Ca²⁺/Na⁺ antiport was also higher in high KCl cultures. Additionally, we found that the endocytotic activity was greater in high KCl cultures than in low KCl cultures, as monitored by the rate of uptake of horseradish peroxidase added to medium. Since the uptake was blocked by an internal Ca²⁺ chelator, the increased endocytotic activity in high KCl cultures might be a consequence of the enhanced Ca²⁺ turnover.     

The change of antithrombin III activity of pregnant women and women on oral contraceptives (author's transl)

Antithrombin 3 (AT 3) activity was examined in pregnant women, women using oral contraceptives (mestranol .1 mg plus norethisterone 2 mg daily or mestranol .05 mg plus norethisterone 1 mg daily), and women on the gestagens alone. AT 3 activity in serum was found to decrease significantly in the third trimester of pregnancy and postpartum period (2 or 3 days); it returned to the level of nonpregnant females 6 or 7 days postpartum. AT 3 in plasma as well as serum was found to decrease significantly after the first month administration of the oral contraceptives. It returned to normal level after the cessation of administration. The successive course of administration again caused the decrease of AT 3 activity. The degree of the decrease became less and less. Finally the decrease was not in effect after 3-5 courses of administration. Norethisterone alone did not cause any change of AT 3 level. (Author's Modified)     

Adenosquamous carcinoma of the gall-bladder with gastric foveolar-type epithelium

An 80 year old Japanese man had adenosquamous carcinoma of the gall-bladder characterized by an adenocarci-noma (AC) in the gall-bladder lumen and a squamous cell carcinoma (SCC) in the Invaded region of the liver. In the AC, the tumor cells consisted of atypical columnar epithelium with pseudostratification, mimicking gastric foveolar epithelium, while atypical signet-ting cells were scattered within the SCC. There was an abrupt transition between the AC and SCC areas. The tumor cells in the AC area were intensely positive for galactose oxidase-Schiff staining, and paradoxical concanavalin A staining revealed these tumor cells to have Class II mucins. lmmunohistochemically, the tumor cells in foveolar-type adenocarcinoma were diffusely positive for cathepsin D. Flow cytometrical analysis of DNA content showed the AC area to be diploid and the SCC area to be aneuploid. The Sphase fraction of the SCC area (46.9%) was larger than that of the AC area (19.5%). The positive rate of immunostaining for proliferating cell nuclear antigen in the SCC area (mean 50.627%) was larger than that of the AC area (mean 3.048%, P < 0.01). These resutts suggest that the AC area of this tumor, histochemically and immunohistochemically, showed gastric foveolar-type characteristics, the SCC component was squamous cell metaplasia of the preexisting AC, and that the SCC area had a greater proliferating capacity than the AC area.     

Analysis of 8-hydroxydeoxyguanosine 5'-monophosphate (8-OH-dGMP) as a reliable marker of cellular oxidative DNA damage after gamma-irradiation

In order to improve 8-hydroxyguanine (8-OH-Gua) detection in DNA, we digested isolated DNA with nuclease P1 and analyzed for 8-hydroxydeoxyguanosine 5'-monophosphate (8-OH-dGMP) using a high-performance liquid chromatography system equipped with an electrochemical detector (HPLC-ECD). The amount of 8-OH-Gua in the DNA was expressed as the ratio of 8-OH-dGMP to deoxycytidine monophosphate (dCMP). Using this analysis, the background level of 8-OH-Gua in DNA from human lung carcinoma cells (A549) was several-fold lower than that obtained by a previous method. A549 cells were exposed to 20-60 Gy of gamma-radiation and an increase in 8-OH-Gua concentration was observed with increasing gamma-ray dose (0.3 residues per 10(7) dCMP per Gy). Moreover, by an immunohistochemical procedure using a commercial FITC-kit, 8-OH-Gua was clearly detected in A549 cells and the fluorescence intensity of cells with oxidative DNA damage increased with the doses of gamma-irradiation. Using an endonuclease nicking assay, we also found that gamma-rays decreased 8-OH-Gua repair activity. The results indicate that 8-OH-dGMP is a useful and sensitive marker for estimating oxidative damage in DNA.     

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.