Formation of multicellular spheroids composed of rat hepatocytes.

A novel method for the preparation of spheroids containing two types of cells (hetero-spheroid) has been successfully developed by using a collagen-conjugated thermo-responsive polymer, poly-N-isopropyl acrylamide, as a cell substratum. The hetero-spheroid was prepared by detaching the confluent monolayer composed of parenchymal and non-parenchymal rat liver cells at a temperature below lower critical solution temperature and culturing it on the non-adhesive substratum. The hetero-spheroid had activity in albumin secretion and PNPA hydrolase activity over a period of 60 days in dishes. These findings suggest that this spheroid formation system is a useful model of an alternative to animal tests of hepatotoxicity.

[Measurement of airway resistance by an interrupter technique in anesthetized dogs during methacholine induced bronchoconstriction].

Airway resistance was measured by an interrupter technique in anesthetized and paralyzed dogs. Bronchoconstriction was then induced by the inhalation of methacholine hydrochloride at a concentration of 25 or 50 mg . ml-1 for ten minutes. Airway resistance was measured again immediately after the inhalation of methacholine and 50 minutes later. Under normal conditions, airway resistance increased with a linear relationship to the expiratory airflow as expressed by a function of Y = K1 + K2X. K1 and K2 were calculated by a least square method. As a result, K1 increased markedly immediately after the inhalation of methacholine and returned to the control level thereafter. However, it was still higher than the control 50 minutes later. On the other hand, no statistically significant changes were observed because the changes in K2 were variable. In some cases, K2 increased, while in others it was unchanged. K2 decreased in more cases, however, and a negative value was often seen. This inverse correlation between flow and resistance was supposed to reflect the occurrence of small airway obstructions during the end expiratory phase. Therefore, it was considered that this method is capable of detecting small airway abnormalities which could not be detected by %FEV1.0.

[The effect of IPPV, with or without PEEP, on central venous pressure].

Changes in central venous pressure (CVP) during intermittent positive pressure ventilation with a Bennett 7200 respirator were measured in 30 postoperative patients without hemodynamic abnormalities. The tidal volume was changed from 300 ml to 900 ml and the PEEP was changed from 0 cmH2O to 8 cmH2O, step by step, respectively. Mean airway pressure (Pmean), maximal airway pressure (Pmax), arterial blood pressure, and heart rate were measured simultaneously with the measurement of CVP. CVP increased linearly with increases in the tidal volume and PEEP. A linear correlation was seen between Pmean and CVP. The value of A was 7.5 +/- 6.2 cmH2O and that of B was 0.32 +/- 0.13 when the equation of the regression line was Y = A + BX, where X was Pmean and Y was CVP. The coefficient of correlation was 0.88 +/- 0.09 (n = 30, P less than 0.01). The value of CVP during intermittent positive pressure ventilation increased linearly at rate which was 32% of the increase in Pmean. The value of CVP was considered to be 7.5 +/- 6.2 cmH2O when Pmean was zero. There was no change in the arterial blood pressure and heart rate throughout the measurement. This suggests that increases in CVP might not reflect any accompanying hemodynamic change.

Coagulability and fibrinolytic changes during veno-venous bypass in liver transplantation.

In clinical liver transplantation, a venous bypass that rechannels the blood flow from the inferior vena cava and portal vein to the superior vena cava has been used to maintain the venous return. However, the usage of mechanical shunt has given rise to derangements of blood coagulability and fibrinolysis. Therefore, changes of coagulability and fibrinolysis during the venous bypass were examined in dogs using a centrifugal pump (Bio-Pump), and the effect of gabexate mesilate for coagulation were studied. Venous bypass from the inferior vena cava and the portal vein to the external jugular vein was performed in mongrel dogs (group A: bypass without pump, group B: bypass with the Bio-Pump, group C: bypass with the Bio-Pump and the addition of gabexate mesilate). In group A, blood pressure gradually decreased, but in groups B and C it maintained the pre-bypass level. All results of coagulation parameters and fibrinolytic measurements of group B were not significantly different from those of group A; only partial thromboplastin time was prolonged in group B. However, this prolongation was effectively prevented by the addition of gabexate mesilate in group C.

Turnover of fibrinopeptide A (FPA) in rabbits.

FPA disappeared from the circulating blood along a double-exponential decay curve consisting of an initial phase (t 1/2 = 1.8 min) and a late phase (t 1/2 = 34.7 min). The rapid decrease in blood FPA was due to the large extravascular space, the size of which was estimated to be about 5 times larger than that of intravascular space. The actual amounts of 125I-FPA distributed to the organs and tissues were generally quite low. However, in the case of the urine, the injected amount of FPA was excreted at the rate of 50% per hour. Thus, the urinary FPA levels may reflect the occurrence of intravascular coagulation.