Biomedical subjects

I Y Liang

Publications and source records attributed to I Y Liang.

24 records · Page 2Linked to original sources

PubMed1976

Intrahepatic microvascular changes in carbon tetrachloride-induced cirrhotic livers in the rat.

Liver cirrhosis was produced in the rat by combined carbon tetrachloride-phenobarbitone treatment, and the microcirculation in the cirrhotic liver was observed by a quantitative in vivo transillumination technique. The total sinusoidal flow in the observed region of the cirrhotic liver did not differ significantly from that in the normal liver, despite the reduced number of sinusoids and the increased portal venous pressure. The cirrhotic liver also presented a fast-velocity population of portal and hepatic venules and sinusoids in addition to the normal slow-velocity population. The possible mechanism of these "arterialized" microvessels is discussed.

Animals↗

PubMed1976

Effect of the ligation of hepatic artery on the microcirculation in the cirrhotic liver in the rat.

The significance of the hepatic arterial supply in the intrahepatic microcirculation in normal and carbon tetrachloride-induced cirrhotic livers was studied by dye injection method and by ligation of the hepatic artery. The in vivo distribution of dye injected into the hepatic artery evidenced the presence of arterio-venous shunts in the cirrhotic liver. When the hepatic artery of the cirrhotic liver was ligated, the elevated portal venous pressure dropped significantly, and the fast-flowing population of microvessels and sinusoids in the bimodal frequency distribution plot disappeared. The fast-flowing microvessel and sinusoids appeared to be the "arterial" microvessels and sinusoids, and they were converted into the slow-flowing venous channels after hepatic arterial ligation. The transmission of arterial pressure via the A-V shunts may be of greater significance in the pathophysiology of portal hypertension than previously believed.

Animals↗

PubMed1975

The terminal hepatic microcirculation in the rat.

The hepatic microcirculation was observed microscopically in the transilluminated liver of the rat. The portal and hepatic venous microvessels were classified into four orders according to their branching hierarchy, and the hepatic sinusoids into branching, direct and interconnecting types according to their topographic arrangements. The diameters of the various orders of microvessels and types of sinusoids were measured by serial photomicrography, and the velocity of the erythrocytes in these various microvessels and sinusoids by the dual-slit photometric technique. The microvascular volume flows were calculated from these data. In both portal and hepatic venous systems, the erythrocyte velocity and the volume flow significantly decreased in successive orders of the microvessels in apparent relation to the cross-sectional areas. The diameters of the three types of sinusoids did not significantly differ, but the velocity of the erythrocytes in the direct sinusoid was significantly faster than that in the branching sinusoid while that in the inter-connecting sinusoid fluctuated widely.

Animals↗

PubMedDate not supplied

Hepatic sinusoidal responses to intraportal injections of phenylephrine and isoprenaline in the rat.

1. Specific alpha- and beta-adrenoreceptor agonists, phenylephrine and isoprenaline, were injected intraportally into the intact rat liver under direct microscopic observation by an in vivo transillumination technique. 2. The diameter of a hepatic sinusoid and the intra-sinusoidal erythrocyte velocity were quantitatively measured, and the sinusoidal volume flow was calculated from these two parameters. 3. Results show that phenylephrine causes a sinusoidal constriction and an increased sinusoidal blood flow, whereas isoprenaline causes the opposite effects on the sinusoids. 4. All the sinusoidal responses to phenylephrine and isoprenaline were dose-dependent and were possibly related to the direct effect of these drugs on the sinusoids.

Animals↗

PubMedDate not supplied

beta 2-Adrenoceptors in rat liver microcirculation.

1. Rat liver sinusoids were observed by a microscopic in vivo transillumination method. The diameter of liver sinusoids and intrasinusoid erythrocyte flow velocities were measured quantitatively by a close-circuit television technique. 2. Both isoprenaline and the selective beta 2-adrenoceptor agonist terbutaline produced a concentration-dependent dilatation of liver sinusoids and slowed erythrocyte flow velocity. The effects of isoprenaline and terbutaline were antagonized by propranolol but not by the selective beta 1-adrenoceptor antagonist atenolol. Propranolol alone produced constriction of the liver sinusoids and increased erythrocyte flow velocity; these effects were not produced by atenolol. 3. The percentage dilatations produced by isoprenaline alone, isoprenaline in the presence of phenoxybenzamine and isoprenaline in the presence of phenylephrine-induced constriction were similar. 4. It is proposed that the beta-adrenoceptors in liver sinusoids are of the beta 2-type, and their physiological role was to counteract constrictor responses produced by alpha-adrenoceptor activity.

Animals↗

PubMedDate not supplied

A comprehensive cardiovascular waveform analysis program for IBM-compatible personal computers.

Computerized cardiovascular waveform processing has become a necessary and fundamental tool in the analysis of physiologic data. The availability of numerous commercial data-analysis programs has significantly enhanced the efficiency of waveform analysis. Many such programs come with their own programming language, which enables the researcher to create an application program suited to a specific series of calculations. Once written, an application program can significantly increase the efficiency with which data from a specific experiment can be analyzed. However, creating or modifying a program for each new experimental protocol can be time-consuming, especially in the error-detection and verification stages. Single-purpose programs also prove somewhat inflexible to unexpected changes in experimental formats. These problems suggested the need for a more flexible program, but one that is nevertheless specifically suited to the analysis of cardiovascular signals. This need led to the development of a program designed in collaboration with surgeons and physiologists. This program addresses some important analysis problems in cardiovascular research, and allows the user to survey and manipulate cardiovascular waveforms in an intuitive and spontaneous manner.

Algorithms↗