Altered ventricular and myocyte response to angiotensin II in pacing-induced heart failure

Alterations in the cardiac response to angiotensin II (Ang II) may contribute to the functional impairment in tachycardia-induced heart failure (congestive heart failure [CHF]). Accordingly, we studied the response to Ang II in eight conscious instrumented dogs before and after inducing CHF. Left ventricular (LV) performance was assessed by measuring LV pressure and LV volume. Isolated myocyte function was evaluated using computer-assessed videomicroscopy. In conscious animals before CHF, Ang II produced a load-dependent slowing of the time constant of LV relaxation (tau) and did not depress intact LV contractile function. After CHF, although Ang II produced a similar increase in LV systolic pressure, the increases in LV diastolic pressure and time constant tau were much greater, and contractile performance was depressed. These changes persisted when the elevation of end-systolic pressure was prevented by nitroprusside. Similar changes were also present after autonomic blockade. In isolated myocytes, before CHF, Ang II (10(-6) mol/L) produced a slight positive inotropic effect. In contrast, after CHF, Ang II produced a negative inotropic effect and slowed the rate of relengthening. The effects in the intact LV and myocytes were reversed by an Ang II AT1 receptor blocker (losartan). We conclude that pacing-induced CHF alters the LV and myocyte response to Ang II, so that Ang II produces direct depressions in intact LV contraction, relaxation, and filling and exacerbates myocyte contractile dysfunction. These effects are mediated through the activation of AT1 receptors.     

Analysis and design for optical video transport distribution systemwith video on demand service

A cost-effective methods of multiplexing, transmitting, and selecting optical video signals is proposed and demonstrated by using appropriate combinations of bidirectional optical trunk-amplifier, medium-density wavelength division multiplexing (WDM) and optical space switching techniques for rapid cost-effective construction. The major factors affecting optical video transport/distribution system design are described. In particular, a tapping-type optical loop-shaped trunk section network is proposed from the viewpoint of system reliability, probability of call-loss, and B-ISDN with analog overlay. The experimental results and design philosophy for an optical selector composed of WDM filters and space switches connected by silica-based waveguide on a chip are also discussed     

CMOS/SIMOX devices having a radiation hardness of 2 Mrad(Si)

Radiation-hardened CMOS/SIMOX devices have been produced by combining SIMOX with a newly developed lateral isolation structure. Even after exposure of these devices up to 2 Mrad(Si) of gamma-ray irradiation, they exhibit sufficient operational characteristics.     

Testis-determining H-Y antigen in XO males of the mole-vole (Ellobius lutescens)

The XO sex chromosome constitution has been found in both sexes of the mole-vole (Ellobius lutescens) belonging to the rodent family Microtinae. This enigmatic species has apparently been enduring a 50% zygotic lethality. The current serological study revealed the presence in XO males and the absence from XO females of H-Y (histocompatibility Y) antigen. In all the mammalian species studied thus far, the expression of H-Y antigen strictly coincided with the presence of testicular tissue and not necessarily with the presence of the Y chromosome. The testis-organizing function of the H-Y gene appears to have been confirmed. In the mole-vole, X linkage of the testis-organizing H-Y gene is favored over its autosomal inheritance. Only X linkage of the H-Y gene creates a compelling evolutionary need to change the female sex chromosome constitution from XX to XO, and to abandon the dosage compensation by an X inactivation mechanism, so that the nonproductive XH-YX zygote can be eliminated as an embryonic lethal. With regard to the electrophoretic mobilities of three X-linked marker enzymes, however, a genetic difference between the male-specific XH-Y and the female-specific X was not detected. This might reflect a relatively recent speciation.     

Characterization of polymerized vesicles derived from polymerizable 1,3-diacylglycero-2-phosphocholines: formation of large unilamellar vesicles by ultrasonication

Summary A series of polymerizable lipids, 1,3-bis(alkana-2,4-dienoyl)-rac-glycero-2-phosphocholines, and 1-(alkana-2,4-dienoyl)-2-0-alkyl-rac-glycero-3-phosphocholine were synthesized. Their vesicle formation and photopolymerization to form polymerized and single walled vesicles were elucidated. The acyl chain length remarkably affected features of liposome formation. 1,3-Bis(dodeca-2,4-dienoyl)-rac-glycero-2-phosphocholine gave large unilamellar vesicles only by ultrasonication of the suspended powders in water, but the lipids with longer acyl chain(s) formed normal and small unilamellar vesicles.See reference 1     

Polymerizable glycerophosphocholines containing terminal 2,4-hexadienyloxy groups and their polymerized vesicles(1)

Summary Polymerizable glycerophosphocholines containing one or two 2,4-hexadienyloxy groups at the terminal of the acyl chains were prepared. Those were 1-[11-(2,4-hexadienyloxy)undecanoyl]-2-0-alkyl-rac-glycero-3-phosphocholines 1, 1-acyl-2-[11-(2,4-hexadienyloxy)undecanoyl]-sn-glycero-3-phosphocholines 2 and 1,2-bis[11-(2,4-hexadienyloxy)undecanoyl]-sn-glycero-3-phosphocholine 3. Those having one hexadienyloxy group formed small unilamellar vesicles. One having two groups formed lipid bilayers, but not unilamellar vesicles. 1 and 2 could form stable microcapsules (polymerized vesicles) with the diameters ranging from 20 to 40 nm.