[Acute liver failure]. / Akutes Leberversagen.

Acute liver failure (ALF) is a rare condition with fatal outcome. Characteristic is rapid onset of liver damage without preexisting liver diseases, including hepatic encephalopathy and coagulopathy. Early and correct diagnosis is essential for further management of patients, since diagnosis impacts therapy choice. Survival of patients with ALF has improved dramatically due to advances in critical care medicine and the use of liver transplantation.

How cocrystals of weakly basic drugs and acidic coformers might modulate solubility and stability.

Cocrystals of a weakly basic drug (nevirapine) with acidic coformers are shown to alter the solubility dependence on pH, and to exhibit a pHmax above which a less soluble cocrystal becomes more soluble than the drug. The cocrystal solubility advantage can be dialed up or down by solution pH.

Imbalance between the endothelial cell-derived contracting factors prostacyclin and angiotensin II and nitric oxide/cyclic GMP in human primary varicosis.

1. The role of the endothelium in the vasomotor control of human veins in the lower extremity is little understood. We tested the hypothesis that the production of relaxing and contracting factors is altered in endothelial cells from varicose saphenous veins which may predispose to the decreased vessel tone observed in primary varicosis. 2. We determined the intracellular accumulation of guanosine 3':5'-cyclic monophosphate cyclic GMP; a measure of nitric oxide production and the release of endothelin and prostacyclin (measured as its stable metabolite 6-keto-prostaglandin F1alpha) from cultured cells derived from the long saphenous veins of patients with primary varicosis (Varicose saphena group, n = 27) or from patients undergoing coronary artery bypass surgery (Healthy saphena group, n = 22). In addition, levels of endothelin, angiotensin II, bradykinin, cyclic GMP and cyclic AMP in plasma from patients with primary varicosis and healthy volunteers (n = 8-11 in each group) were determined. 3. Although basal cyclic GMP levels were similar, more cyclic GMP accumulated in response to histamine (1-100 micromol l[-1]) in cells from varicose saphenous veins (0.75 +/- 0.1 pmol per well) than in cells from veins without varicosis (0.27 +/- 0.05 pmol per well). Furthermore, the relaxant potency of nitroprusside (1 nmol l(-1) - 300 micromol l[-1]) in vitro was higher for varicose veins (mean EC50 = 5.9 micromol l(-1); n = 8) than healthy veins (mean EC50 = 20.0 micromol l(-1); n = 7). 4. The production of prostacyclin was significantly less in cells from varicose than healthy saphenous veins (66 +/- 8.7 and 121 +/- 20.1 nmol g(-1) protein), but the production of endothelin was similar in both groups. Prostacyclin (3 nmol l(-1) 30 micromol l[-1]) consistently contracted rings of varicose saphenous vein in vitro with a mean EC50 value of 10-20 micromol l(-1) (n = 7); the maximum tension generated was approximately 50% of that of a completely depolarizing solution of K+ (120 mmol l[-1]). 5. In plasma from patients with varicose veins, levels of cyclic GMP were higher than in healthy controls (9.2 +/- 0.03 and 7.2 +/- 0.02 nmol l[-1]), levels of angiotensin II were lower (81 +/- 11.5 and 147 +/- 21.7 pmol l[-1]), and levels of endothelin, cyclic AMP, and bradykinin were not different. 6. It is concluded that endothelial cells from diseased saphenous veins secrete less constrictor mediators than cells from healthy veins and that in diseased veins the nitric oxide/cyclic GMP system is up-regulated which may shift the balance of vasoactive factors towards vasodilatation and contribute to the development of primary varicosis.

Experimental in vitro endothelialization of cardiac valve leaflets.

This study reports our results with vitro endothelialization of fresh nonpreserved homograft valve leaflets compared with mild alternatively preserved valves and valves treated by preservation procedures commonly used for commercially available tissue valves. In vitro lining of biological heart valves with cultured autologous endothelial cells might help prevent the detrimental effects of degeneration on valve durability. To investigate the growth characteristics of endothelial cells on valve bioprostheses, three different methods of storage and preservation were compared. After precoating with fibronectin and seeding of 4.4 x 10(4) endothelial cells/cm2 onto the different leaflet surfaces, primary adherence, growth kinetics, morphology, and maintenance of monolayer integrity were studied over a period of 10 days. On valve leaflet surfaces of group 1 (fresh nonpreserved homograft valve leaflets) and group 2 (mild alternatively preserved valves), endothelial cells grew to persistent monolayers between days 6 and 10. In contrast, endothelial cell proliferation with monolayer growth could not be achieved on the group 3 leaflets (preserved like commercially available biological valve prostheses). In that group, no viable endothelial cells could be found on the valve surfaces 2 days after seeding. These results demonstrate the theoretical feasibility of endothelializing biological heart valve leaflets in vitro if they are not preserved and stored according to commonly used procedures. Provided such an endothelium can withstand the mechanical forces after implantation in vivo, in vitro endothelialization might contribute either to the development of new biological heart valves for modern cardiac surgery or to the improvement of clinical results with homograft valve transplants.

In situ cannulation, microgrid follow-up and low-density plating provide first passage endothelial cell masscultures for in vitro lining.

A rapid and reliable harvest and culture technique was developed to provide a sufficient number of autologous endothelial cells for the confluent in vitro lining of cardiovascular prostheses. Enzymatic endothelial cell detachment was achieved by the in situ application of collagenase to short vessel segments. This harvest technique resulted in a complete lack of contaminating smooth muscle cells in all of 124 cultures from nonhuman primates and 13 cultures from human adults. The use of a microgrid technique enabled the daily in situ quantification of available endothelial cells. To assess ideal plating densities after passage the population doubling time was continuously related to the cell density. Surprisingly, a low plating density of 1.5 X 10(3) endothelial cells/cm2 achieved 43% shorter cell cycles than the usual plating density of 1.0 X 10(4) endothelial cells/cm2. Moreover, low density plating enabled mass cultures after one single cell passage, thereby reducing the cell damaging effect of trypsin. When the growth characteristics of endothelial cells from five anatomically different vessel sites were compared, the external jugular vein--which would be easily accessible and dispensable in each patient--proved to be an excellent source for endothelial cell cultures. By applying in situ administration of collagenase, low density plating and microgrid follow-up to adult human saphenous vein endothelial cells, 14,000,000 first passage endothelial cells--sufficient for the in vitro lining of long vascular prostheses--were obtained 26.2 days after harvest. (95% confidence interval:22.3 to 32.2 days).

Reduced reproductive capacity of freshly harvested endothelial cells in smokers: a possible shortcoming in the success of seeding?

In an attempt to explain the failure of first clinical trials of autologous endothelial seeding in smokers, the initial reproductive capacity of saphenous vein endothelial cells from smokers and nonsmokers was studied by a replicate microwell technique. Endothelial cells were enzymatically harvested from saphenous vein segments of patients with coronary bypasses (21 smokers and 18 nonsmokers). After 15 minutes (group A) and 7 minutes (group B) of collagenase exposure, the endothelial cell harvest from donors who smoked was 41% (p less than 0.02) lower for group A and 30% (p less than 0.2) lower for group B than that from nonsmokers. In analogy, the viable cell yield was 32% (p less than 0.04) and 29% (p less than 0.05) lower for groups A and B, respectively, in cultures from donors who smoked. Daily cell counts over an ensuing 10-day period also revealed a significant difference in the proliferative behavior of endothelial cells from smokers and nonsmokers. Whereas endothelial cells from nonsmokers regularly entered the exponential phase of proliferation on day 4.4 +/- 1.8 (group A) and day 4.6 +/- 1.3 (group B), endothelial cells from smokers reached the logarithmic growth phase either with delay (day 6.8 +/- 2.1, group A) or remained completely quiescent (group B). Lower harvest efficiency and suppressed reproductive capacity of endothelial cells in smokers--on top of an already critically low inoculum in single-staged endothelial cell seeding--might explain the failure of initial clinical trials.