Abstract. Mature adult parenchymal hepatocytes, typically of restricted capacity to proliferate in culture, can now enter into clonal growth under the influence of hepatocyte growth factor (scatter factor) (HGF/SF), epidermal growth factor (EGF), and transforming growth factor et (TGFo 0 in the presence of a new chemically defined medium (HGM). The expanding populations of hepatocytes lose expression of hepatocyte specific genes (albumin, cytochrome P450 IIB1), acquire expression of markers expressed by bile duct epithelium (cytokeratin 19), produce TGFot and acidic FGF and assume a very simplified morphologic phenotype by electron microscopy. A major change associated with this transition is the decrease in ratio between transcription factors C/EBPo~ and C/EBP[3, as well as the emergence in the proliferating hepatocytes of transcription factors AP1, NFKB. The liver associated transcription factors HNF1, HNF3, and HNF4 are preserved throughout this process. After population expansion and clonal growth, the proliferating hepatocytes can return to mature hepatocyte phenotype in the presence of EHS gel (Matrigel). This includes complete restoration of electron microscopic structure and albumin expression. The hepatocyte cultures however can instead be induced to form acinar/ductular structures akin to bile ductules (in the presence of HGF/SF and type I collagen). These transformations affect the entire population of the hepatocytes and occur even when DNA synthesis is inhibited. Similar acinar/ductular structures are seen in embryonic liver when HGF/SF and its receptor are expressed at high levels. These findings strongly support the hypothesis that mature hepatocytes can function as or be a source of bipotential facultative hepatic stem cells (hepatoblasts). These studies also provide evidence for the growth factor and matrix signals that govern these complex phenotypic transitions of facultative stem cells which are crucial for recovery from acute and chronic liver injury.

Acetaminophen hepatotoxicity after a dose of 4 to 10 g/d was associated with fasting and less commonly with alcohol use. Patients who developed hepatoxicity after taking acetaminophen doses of greater than 10 g/d for therapeutic purposes were alcohol users. Acetaminophen hepatotoxicity after an overdose appears to be enhanced by fasting in addition to alcohol ingestion.

Malignant strictures of the extrahepatic bile ducts are difficult to distinguish from benign strictures, particularly in patients with primary sclerosing cholangitis. Because attempts at diagnosing small cancers with fine-needle aspiration biopsy are not possible in the absence of an aesociated mass lesion and because the sensitivity of exfoliative biliary cytology is controversial, brush cytology has been used as a potential means of establishing a specific diagnosis of bile duct carcinoma. Herein we report our experience with this technique when performed on 65 patients over a 5-yr period. Each had at least one brushing. Thirty-seven were found to have bile duct carcinoma and 28 were found to have benign strictures. Of these 37, the first brushing was positive for malignancy in 15 (40%), whereas four (11%) had cells suspected but not diagnostic of malignancy. Thirteen patients with bile duct carcinoma whose initial brushings were negative for malignancy had second brushings. Of these, five (38%) had malignant cells, whereas three (24%) yielded suspicious cells. Three of the eight whose first two brushings were negative for malignancy were found to have malignant cells on the third brushing. In contrast, of the 28 patients with benign strictures, malignant cells were never found. However, in two patients, suspicious cells were reported with the h t but not the second brushing. A single negative or suspicious cytological &ding decreased the probability of bile duct carcinoma to 43%. Two and three sequential negative tests reduced the probability to 32% and 0%, respectively. When suspicious cytological findings were excluded from the negative results, the probability of having bile duct carcinoma was further reduced to 41%, 20% and 0%, respectively.Using these results, we conclude that (a) a single cytological brushing of a bile duct stricture has a low yield, (b) the sensitivity of the test increases with repeated attempts, (c) the probability of having bile duct carcinoma after three sequential negative cyto-

These results indicated that AUDs during adolescence were associated with health problems, including modest but demonstrable liver injury. Self-reported health problems were probably best understood, in this context, as a negative emotionality manifestation.

Preclinical safety and efficacy evaluation of a novel bioartificial liver support system (BLSS) was conducted using a D-galactosamine canine liver failure model. The BLSS houses a suspension of porcine hepatocytes in a hollow fiber cartridge with the hepatocytes on one side of the membrane and whole blood flowing on the other. Porcine hepatocytes harvested by a collagenase digestion technique were infused into the hollow fiber cartridge and incubated for 16 to 24 hours prior to use. Fifteen purpose-bred male hounds, 1-3 years old, 25-30 kg, were administered a lethal dose, 1.5 g/kg, of D-galactosamine. The animals were divided into three treatment groups: (1b) no BLSS treatment (n = 6); (2b) BLSS treatment starting at 24-26 h post D-galactosamine (n = 5); and (2c) BLSS treatment starting at 16-18 h post D-galactosamine (n = 4). While maintained under isoflurane anesthesia, canine supportive care was guided by electrolyte and invasive physiologic monitoring consisting of arterial pressure, central venous pressure, extradural intracranial pressure (ICP), pulmonary artery pressure, urinary catheter, and end-tidal CO2. All animals were treated until death or death-equivalent (inability to sustain systolic blood pressure > 80 mmHg for 20 minutes despite massive fluid resuscitation and/or dopamine administration), or euthanized at 60 hours. All animals developed evidence of liver failure at 12-24 hours as evidenced by blood pressure lability, elevated ICP, marked hepatocellular enzyme elevation with microscopic massive hepatocyte necrosis and cerebral edema, elevated prothrombin time, and metabolic acidosis. Groups 2b and 2c marginally prolong survival compared with Group 1b (pairwise log rank censored survival time analysis, p = 0.096 and p = 0.064, respectively). Since survival times for Groups 2b and 2c are not significantly different (p = 0.694), the groups were combined for further statistical analysis. Survival times for the combined active treatment Groups 2b and 2c are significantly prolonged versus Group 1b (p = 0.047). These results suggest the novel BLSS reported here can have a significant impact on the course of liver failure in the D-galactosamine canine liver failure model. The BLSS is ready for Phase I safety evaluation in a clinical setting.

It has been suggested that the sulfur amino acids in protein are responsible for the calciuria observed after protein ingestion. This hypothesis was tested by feeding meals containing either 15 g protein (control), 45 g protein (high protein), or 15 g protein plus sulfur amino acids equivalent to those in the high protein diet. Compared to the control, the high protein diet caused an increase in urinary calcium and sulfate and a decrease in the renal reabsorption of calcium. In contrast, the sulfur amino acid supplement had no effect on calcium excretion or reabsorption. Net acid excretion was unaffected by dietary treatment.

These results indicated that AUDs during adolescence were associated with health problems, including modest but demonstrable liver injury. Self-reported health problems were probably best understood, in this context, as a negative emotionality manifestation.

This experiment was designed to test whether protein consumption reduces the amount of filtered calcium reabsorbed by the kidney. Nine subjects were each fed meals containing 18 g protein and 54 g protein. The intake of energy, sodium, calcium, phosphorus, magnesium and zinc was similar in the two meals. For 4 hours after the meal, measurements were made of serum calcium (total and filterable), serum creatinine, and urinary calcium, creatinine, zinc and nitrogen. Calcium reabsorption was calculated in five clearance periods, as (filterable calcium X GFR) minus urinary calcium. Urinary calcium, zinc and nitrogen were significantly higher between 2 and 4 hours after consumption of the high protein meal. Protein level did not affect urine pH or volume, serum total or filterable calcium & or GFR. The percentage reabsorption of filtered calcium was significantly lower 0.5 hours after the high protein meal, so that at 2.5 hours, reabsorption was 98.0% compared to 98.7% after the lower protein meal. We conclude that protein consumption reduces the amount of calcium reabsorbed by the kidney.