Interleukin-6 is the major regulator of acute phase protein synthesis in adult human hepatocytes.

The three monokines interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), and interleukin-6 (IL-6) modulate acute phase plasma protein synthesis in adult human hepatocytes. Only IL-6 stimulates the synthesis of the full spectrum of acute phase proteins as seen in inflammatory states in humans, i.e. synthesis and secretion of C-reactive protein, serum amyloid A, fibrinogen, alpha 1-antitrypsin, alpha 1-antichymotrypsin and haptoglobin are increased while albumin, transferrin and fibronectin are decreased. IL-1 beta as well as TNF alpha, although having a moderate effect on the positive acute phase proteins and inhibiting the synthesis of fibrinogen, albumin and transferrin, fail to induce serum amyloid A and C-reactive protein. These data suggest that IL-6 plays the key role in the regulation of acute phase protein synthesis in human hepatocytes.

Intracellular glutathione in human hepatocytes incubated with S-adenosyl-L-methionine and GSH-depleting drugs.

The present study was undertaken to investigate (a) whether S-adenosyl-L-methionine (SAMe) added to culture medium can increase intracellular glutathione (GSH) levels in human hepatocytes and (b) whether SAMe can prevent the GSH depletion found in human hepatocytes incubated with GSH-depleting drugs (paracetamol, opiates, ethanol). Incubation of hepatocytes with increasing concentrations of SAMe resulted in a dose-dependent elevation of intracellular GSH content, which reached its maximum (35% increase) at 30 microM after 20 h. SAMe, as the only sulfur source in the medium, was efficient in repleting GSH-depleted hepatocytes following treatment with diethyl maleate. Incubation of human hepatocytes with SAMe attenuated the GSH depletion of cells incubated with toxic concentrations of paracetamol (2 mM), heroin (0.5 mM) and methadone (0.2 mM). A decrease in GSH due to exposure of hepatocytes to 50 mM ethanol was prevented when SAMe was simultaneously added to ethanol, and human hepatocytes maintained their GSH levels like non ethanol-treated cells. The experimental results of our work give the first direct evidence of the ability of exogenously administered SAMe to increase intracellular GSH levels in human hepatocytes and to prevent the GSH depletion caused by paracetamol, opiates and ethanol.

The effects of buprenorphine on the metabolism of human hepatocytes.

Adult human hepatocytes cultured in chemically defined conditions were used as a biological model to examine the metabolic effects of buprenorphine on the human liver. Cell extension and monolayer formation of human hepatocytes were affected in a dose-dependent manner after 24 hr of exposure to the drug. According to the several endpoints evaluated (cellular protein, intracellular lactate dehydrogenase activity and the MTT test), the half-maximal cytotoxic effect (IC(50)) of buprenorphine was close to 100 mum. Longer exposure of hepatocytes to buprenorphine (72 hr) increased its cytotoxicity, and the IC(50) of the drug was reduced to 50 mum. Lower concentrations of the drug (in the 5-50-mum range) significantly impaired the metabolic functions of the hepatocytes. Incubation of the cells with 40 mum-buprenorphine for 24 hr reduced the glycogen content to 60% of the initial content and 50 mum-buprenorphine inhibited glycogen synthesis in glucagon-depleted human hepatocytes by about 40%. Albumin synthesis was the most sensitive metabolic parameter, and 24-hr exposure of hepatocytes to 10 mum-buprenorphine, a concentration with no apparent cytotoxic effects, reduced albumin synthesis to 50%. Urea synthesis was moderately affected by buprenorphine. Glutathione content was reduced in a dose-dependent manner by the drug, reaching a minimum value (60% of control values) after 6 hr of exposure to 50 mum of the opiate. Analysis of the data on the therapeutic dosage of buprenorphine and other opiates showed that the toxicity risk index of buprenorphine, like that of meperidine, lies somewhere between that of morphine and methadone.

[Multiple nosocomial infections. An incidence study]. / Infecciones nosocomiales múltiples. Un estudio de incidencia.

BACKGROUND: Some studies point out that around 30%-50% of the nosocomial infections (NI) are multiple (MNI) and are found in 21%-30% of the patients with NI. The significance of these data and their potential consequences have led the authors to perform this study. PATIENTS AND METHODS: A longitudinal descriptive study was carried out on the incidence and characteristics of NI (MNI and single nosocomial infection [SNI]) in 26,977 patients admitted to a county hospital from 1991 to 1993. RESULTS: NI was detected in 1,246 patients with 31% presenting MNI appearing in 15% of the patients. MNI predominated in males, had a mean age were 5 to 12 years higher than the patients with SNI with a mean hospital stay of between 13-28 days more than the SNI group. The MNI were significantly less frequent in the Urology, Gynecology and Obstetrics Departments and were more frequent in the Intensive Care Unit. The localization of the infection varied significantly among the patients with one or several infections. Bacteremia, pneumonia and soft tissue infections were significantly more frequent in MNI patients. CONCLUSIONS: Multiple nosocomial infections are frequent and their basic characteristics are significantly different from those of single nosocomial infections. The patients who acquire SNI should be carefully followed to avoid the appearance of MNI.

Main pancreatic duct: morphlogy after acute biliary pancreatitis with magnetic resonance cholangiopancreatography after secretin stimulation.

OBJECTIVE: to assess whether a magnetic resonance cholangiopancreatography performed after an acute biliary pancreatitis leads to pancreatic morphological alterations and if secretin stimulation influences the visualization of the pancreatic tree. METHOD: forty patients with acute biliary pancreatitis, 25 female (62,5/) and 15 male (37,5/), 27 mild and 13 severe, were prospectively and consecutively studied. All patients had undergone cholecystectomy. No altered pancreatic functions were observed. Morphology of the pancreas and of the main pancreatic duct were assessed by magnetic resonance cholangiopancreatography five years after the episode of pancreatitis and a comparative study between patients and case controls was carried out. Secretin was given in 16 cases in whom the visualization of the duct was incomplete or absent. Ductal morphology before and after secretin stimulation was compared. RESULTS: significant differences were observed when the diameter and length of the main pancreatic duct were compared in patients and control cases and was completely visualized in 60% of the cases, and could be seen in all patients after secretin stimulation. The comparative statistical analysis of the length and diameter of the pancreatic duct before and after the secretin stimulation showed significant differences. CONCLUSION: acute biliary pancreatitis leads to morphological alterations, regarded as scar lesions which do not become chronic. Secretin stimulation improves the visualization of the main pancreatic duct.

[Anti-tuberculosis drug resistance of Mycobacterium tuberculosis in the area of the Hospital de Sagunto from 1999 to 2004]. / Resistencias de Mycobacterium tuberculosis en el área del Hospital de Sagunto desde 1999 al 2004.

OBJECTIVES: This study aimed to know the drug resistance patterns of Mycobacterium tuberculosis, specifically primary drug resistance to isoniazid, in the area of the Hospital de Sagunto and to study the clinical characteristics and the risk factors associated with them. MATERIAL AND METHODS: Patients included were those who were diagnosed of tuberculosis and whose M. tuberculosis strains were isolated in culture of a clinical sample and in whom a susceptibility test against the first line anti-tuberculosis drugs was performed from January 1999 to December 2004. Risk factors and clinical characteristics of the patients were gathered from the case- history. RESULTS: The total number of strains isolated was 77 and the global rate of resistance was 14.1%. Rate of primary drug resistance was 12.1%, and acquired 27%. No multidrug resistant case was detected. Primary drug resistance was 3% to isoniazid, 3% to rifampin, 3% to pyrazinamid, 4.5% to ethambutol and 3% to streptomycin. Acquired drug resistance was 9.1% against isoniazid and 27% against streptomicin, no resistance against the other drugs tested being found. CONCLUSIONS: The low level of primary drug resistance against isoniazid allows us to start treatment with three-drug regimes in new cases of native population. In our hospital area, the risk factors associated with drug resistances were smoking habit and alcoholism. Although all patients with drug resistance presented pulmonary disease, the differences were not statistically significant. However, the higher rate of pleural effusion in patients with drug resistance was statistically significant.

Toxicity of paracetamol in human hepatocytes. Comparison of the protective effects of sulfhydryl compounds acting as glutathione precursors.

The hepatotoxicity of N-acetyl-p-aminophenol (acetaminophen, paracetamol) was investigated in hepatocyte cultures obtained from eight different human liver biopsies. Incubation of hepatocytes with paracetamol resulted in a dose- and time-dependent glutathione depletion. Glutathione decreased linearly for 8 h, reaching a minimum after 12 h of exposure. Cytotoxicity, assessed as loss of cellular protein from plates, was observed only when glutathione decreased below 20% for more than 12 h. However, in one donor, cytotoxicity was observed with even a moderate glutathione decrease. Prestimulation of hepatocytes with 1 mM phenobarbital or 2 microM methylcholanthrene for 48 h did not lead to a significant increase of paracetamol toxicity, although the glutathione levels in 3-methylcholanthrene-treated cells were somewhat lower. Several metabolic precursors were examined in vitro for their ability to increase intracellular glutathione and the results showed the following sequence: N-acetylcysteine greater than thioproline greater than cysteine greater than 2-oxo-4-thiazolidine carboxylic acid greater than methionine. However, only N-acetylcysteine, thioproline, and cysteine substantially increased glutathione levels when 1 mM paracetamol was present in the incubation medium and thus prevented its toxicity. N-acetylcysteine elevated glutathione even after 24 h of preexposure to paracetamol. The fact that cell damage did not correlate with glutathione levels in all human cultures suggests that glutathione depletion may not be the only determinant of paracetamol toxicity in human hepatocytes.

Cell cycle progression proteins (cyclins), oncogene expression, and signal transduction during the proliferative response of human hepatocytes to hepatocyte growth factor.

Human hepatocytes stimulated with human recombinant hepatocyte growth factor (h-rHGF) (10 ng/mL) displayed a characteristic lag period before entering into the S phase. The duration of this delay was dependent on the timing of h-rHGF addition to cultures. The highest peak of DNA synthesis was observed at 120 hours of culture when hepatocytes were stimulated with h-rHGF at 72 hours of culture. This was accompanied by an early peak of c-jun and c-fos synthesis (3 hours after addition of h-rHGF) followed by c-myc (6 hours) and increased expression of cyclins A, B, D, and E (12 hours after h-rHGF). A significant dose-dependent increase in inositol 1,4,5-P3 was observed within 45 seconds after stimulation with the factor. This was followed by an immediate increase in the cytosolic-free calcium. Cyclic adenosine monophosphate (cAMP) levels did not change after stimulation with the factor. Tyrosine phosphorylation seems to be an early event in the course of the stimulatory effect of h-rHGF on DNA synthesis of hepatocytes; genistein, a tyrosine kinase inhibitor, impaired the stimulatory effect of h-rHGF on DNA synthesis dose dependently. On the other hand, the action of the factor was negatively regulated by protein kinase C activation, as shown by the increased stimulatory effect of h-rHGF on DNA synthesis upon inhibition of protein kinase C by H7.

Hepatotoxicity of the opioids morphine, heroin, meperidine, and methadone to cultured human hepatocytes.

Adult human hepatocytes in chemically defined culture conditions were incubated with morphine, heroin, meperidine, and methadone to investigate their potential hepatotoxicity to human liver. Cytotoxic effects were observed at about 100 times the plasma concentrations required to produce analgesia in human nonaddicts. Concentrations of 1 mM morphine, heroin, and meperidine reduced the glycogen content by 50%, while even 0.2 mM methadone produced a depletion of 70% after 24 h of treatment. Concentrations of 0.8 mM morphine and heroin, 0.4 mM meperidine, and 0.005 mM methadone inhibited the albumin synthesis by about 50% after 24 h of pretreatment. Intracellular glutathione was reduced to 50% of that of controls after 2-3 h of incubation with 2 mM morphine and 1 mM heroin, while 1 mM meperidine and 0.2 mM methadone produced a reduction of about 30% after 6 h incubation. The results show that therapeutic doses of the opioids is unlikely to produce irreversible damage to human hepatocytes, but opiate doses during tolerance or abuse may be a cause of liver dysfunction.

Effects of hepatocyte growth factor on the growth and metabolism of human hepatocytes in primary culture.

The effect of recombinant human hepatocyte growth factor (h-rHGF), a potent mitogen for hepatocytes, was investigated in primary cultures of human hepatocytes. Here, we describe a series of experiments to investigate the kinetics of its mitogenic action, as well as its metabolic effects on cultured human hepatocytes. The h-rHGF is a potent signal for initiating DNA synthesis in human hepatocytes, with maximal stimulatory effects at 10 ng/mL (0.1 pmol/L). The kinetics of DNA synthesis showed a lag of about 48 to 72 hours, followed by a maximum at 96 hours. At least 48 hours of continuous exposure to h-rHGF are required to initiate DNA synthesis in quiescent human hepatocytes. Cell cycle analysis by flow cytometry showed that most of quiescent 2c cells have left G0/G1 and entered the cell cycle (S and G2/M phases) by 96 hours of continuous exposure to h-rHGF. When compared with other growth factors, h-rHGF was a much more potent mitogen. The effects of 10 ng/mL (0.1 pmol/L) h-rHGF on DNA synthesis were only achieved by 1.5 pmol/L epidermal growth factor (EGF), 0.1 mumol/L insulin, or 1 mumol/L glucagon. It is noteworthy that the effect of h-rHGF was potentiated by glucagon but not by insulin or EGF. The stimulatory effect of HGF on DNA synthesis was gradually inhibited by h-rHGF transforming growth factor beta (TGF-beta) in the range 1 to 10 ng/ml. The HGF also influenced the expression of other hepatic genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug biotransformation by human hepatocytes. In vitro/in vivo metabolism by cells from the same donor.

BACKGROUND/AIMS: Cultured human hepatocytes are considered a close model to human liver. However, the fact that hepatocytes are placed in a microenvironment that differs from that of the cell in the liver raises the question: to what extent does drug metabolism in vitro reflect that of the liver in vivo? This issue was examined by investigating the in vitro and in vivo metabolism of aceclofenac, an analgesic/anti-inflammatory drug. METHODS: Hepatocytes isolated from programmed liver biopsies were incubated with aceclofenac, and the metabolites formed were investigated by HPLC. During the course of clinical recovery, patients were given the drug, and the metabolites, largely present in the urine, were analyzed. In vitro and in vivo data of the same individual were compared. RESULTS: The relative abundance of oxidized metabolites in vitro (i.e. 4'OH-aceclofenac + 4'OH-diclofenac vs. total hydroxylated metabolites; Spearman's p = 0.855), as well the hydrolysis of aceclofenac (4'OH-diclofenac vs. 4'OH-aceclofenac + 4'OH-diclofenac; p = 0.691) correlated well with in vivo data. The conjugation of the drug in vitro (24.6 +/- 7.6%) was lower than that in vivo (44.9 +/- 5.3%). The rate of 4'OH-aceclofenac formation in vitro correlated with the amount of metabolites excreted in urine after 16 h (p = 0.95). CONCLUSIONS: The in vitro/in vivo metabolism of the drug was surprisingly similar in each patient. The variability observed in vitro reflected an existing phenotypic variability among donors.

Acute-phase response of human hepatocytes: regulation of acute-phase protein synthesis by interleukin-6.

Human hepatocytes in primary culture were used as a model system to investigate the mechanism(s) involved in the induction of the acute-phase response in human liver. Hepatocytes were incubated with increasing amounts of recombinant human interleukin-1 beta, recombinant interleukin-6 and tumor necrosis factor-alpha. Synthesis of C-reactive protein was studied at the mRNA and protein levels. Only recombinant interleukin-6 was capable of inducing C-reactive protein-mRNA and C-reactive protein-protein synthesis. Also, fibrinogen and alpha-1-antitrypsin synthesis measured by immunoprecipitation with specific antisera increased in a dose-dependent, time-dependent manner, whereas albumin synthesis decreased to about 50% of controls. Maximal effects were observed at 100 to 300 units of recombinant interleukin-6/ml culture medium after 20 hr of incubation. Although the synthetic glucocorticoid dexamethasone slightly modulated the effect of recombinant interleukin-6, it was not an absolute requirement for the induction of acute-phase protein synthesis in human hepatocytes. In pulse-chase experiments it was shown that the time course of the disappearance of the acute-phase proteins from the cells and their appearance in the medium is not influenced by recombinant interleukin-6. This finding suggests that recombinant interleukin-6 exerts its regulatory effect on acute-phase protein synthesis at the pretranslational level.

Genetic alterations and oxidative metabolism in sporadic colorectal tumors from a Spanish community.

Deletions of loci on chromosomes 5q, 17p, 18q, and 22q, together with the incidence of p53 mutations and amplification of the double minute-2 gene were investigated in the sporadic colorectal tumors of 44 patients from a Spanish community. Chromosome deletions were analyzed by means of loss of heterozygosity analysis using a restriction fragment length polymorphism assay. Allelic losses were also detected by polymerase chain reaction (PCR)-single-stranded conformation polymorphism (SSCP) analysis of a polymorphic site in intron 2 of the p53 gene. The percentages of genetic deletions on the screened chromosomes were 39.3% (5q), 58.3% (17p), 40.9% (18q), and 40% (22q). Mutations in p53 exons 2-9 were examined by PCR-SSCP analysis and direct sequencing of the mutated region. Twenty of 44 tumor samples (45.45%) showed mutations at various exons except for exons 2, 3, and 9, the most frequent changes being G-->T transversion and C-->T transition. Because oxygen-free radicals play a role in the carcinogenesis process, we evaluated the oxidative status of the colorectal tumors. Antioxidant activities, lipid peroxidation, and DNA-damaged product concentrations in colon tumors and normal mucosa were compared. In tumor tissues, superoxide dismutase and catalase decreased fourfold and twofold, respectively, whereas glutathione peroxidase and reduced glutathione increased threefold. Malondialdehyde and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were twofold higher in colorectal tumors than in normal mucosa. Seven of 10 DNA tumor samples (70%) showing higher values of 8-OHdG also had genetic alterations at different chromosomal loci. In these samples, the p53 gene was deleted or mutated in 71.4% of cases. We concluded that the observed changes in the oxidative metabolism of the tumor cells and the consecutive increase in DNA damage may potentiate the genomic instability of different chromosomal regions, leading to further cell malignancy and tumor expansion.

Pancreatic function after severe acute biliary pancreatitis: the role of necrosectomy.

OBJECTIVES: To investigate the recovery of pancreatic function after severe acute biliary pancreatitis (ABP), especially the influence of necrosectomy on endocrine and exocrine functions. METHODS: Prospective cohort study including 39 patients with severe ABP. According to need or no need for surgical necrosectomy, patients were further subdivided into 2 groups. Functional pancreatic evaluation was carried out 12 months after the ABP episode. Endocrine function was evaluated by an oral glucose tolerance test and exocrine function by fecal fat excretion, fecal chymotrypsin (FQ), and secretin-cerulein tests (SCT). RESULTS: Most of the patients with necrosectomy had an abnormal exocrine pancreatic function, with steatorrhea in 25%. In the group without surgery, exocrine function was pathologic in only 13.3% and there were no cases of steatorrhea. Endocrine function was pathologic in 75% of patients undergoing necrosectomy versus 26.7% in the nonoperated group. In this latter group, the patients with abnormal endocrine function did not require insulin therapy, while in 33.3% of patient in the necrosectomy group insulin was necessary. CONCLUSIONS: In our homogeneous series of severe ABP, necrosectomy impaired significantly pancreatic endocrine and exocrine function. On the other hand, most patients with the same origin and severity index, but without surgical debridement, maintained normal pancreatic function.

Oncostatin M down-regulates basal and induced cytochromes P450 in human hepatocytes.

The effects of oncostatin M on the expression of different cytochrome P450 (CYP) isozymes has been investigated in human hepatocytes. The dose-response and time-course analyses of effects on CYP1A2 and CYP3A4 isozymes revealed that maximal inhibition was reached after 48 hr of exposure of human hepatocytes to 25 units/ml oncostatin M. Reductions in CYP1A2 and CYP3A4 activity produced by oncostatin M correlated with decreases in protein content, de novo protein synthesis and specific mRNA levels, thus suggesting that oncostatin M could down-regulate CYP expression at the transcriptional level. The inhibitory potency of oncostatin M on CYP expression was compared with that of other cytokines belonging to the interleukin-6 receptor family (interleukin-6, interleukin-11 and leukemia inhibitory factor), and interferon-gamma, which is recognized to inhibit human CYP expression, and granulocyte colony-stimulating factor, a cytokine that shares structural homology with the interleukin-6 family but has a different transduction signal. Maximal reductions in CYP1A2 activity were reached after 48 hr of treatment with cytokines. At that time, oncostatin M showed the highest inhibitory effects on CYP1A2 activity (38% of control), followed by interferon (49% of control) and interleukin-6 (60% of control), whereas minor effects were produced by the other cytokines (74-80%). Comparable decreases were observed for CYP2A6, CYP2B6 and CYP3A4 activities. Enzymatic activity and de novo protein synthesis of 3-methylcholanthrene-induced CYP1A2 and dexamethasone-induced CYP3A4 were also reduced to a much greater extent by oncostatin M than by other cytokines. The results show that oncostatin M is the most effective cytokine in down-regulating CYP isozymes in human hepatocytes, and its effects were evident even after removal of the cytokine from the culture medium.

Culture of human hepatocytes from small surgical liver biopsies. Biochemical characterization and comparison with in vivo.

High yields of human hepatocytes (up to 23 X 10(6) viable cells/g) were obtained from small surgical liver biopsies (1 to 3 g) by a two-step collagenase microperfusion method. Cell viability was about 95%, attachment efficiency of hepatocytes seeded on fibronectin-coated plates was 80% within 1 h after plating, and cells survived for about 2 wk in serum-free Ham's F12 containing 0.2% bovine serum albumin, 10(-8) M insulin, and 10(-8) M dexamethasone. To evaluate the metabolism of human hepatocytes in serum-free conditions, we measured their most characteristic biochemical functions and compared them to those reported for human liver. After 24 h in culture, glycogen content was 1250 +/- 177 nmol glucose/mg cell protein and remained stable for several days. Gluconeogenesis from lactate in hormone-free media was (3.50 +/- 0.17 nmol glucose.mg-1.min-1) similar to that reported for human liver. Insulin at 10(-8) M activated glycolysis (X1.40) and glycogenesis (X1.34), and glucagon at 10(-9) M stimulated gluconeogenesis (X1.35) and glycogenolysis (X2.18). Human hepatocytes synthesized albumin, transferrin, fibrinogen, alpha 1-antitrypsin, alpha 1-antichymotrypsin, alpha 1-acid glycoprotein, haptoglobin, alpha 2-macroglobulin, and plasma fibronectin and excreted them to the culture medium. Maximum protein synthesis was stimulated by 10(-9) M dexamethasone. Basal urea synthesis oscillated between 2.5 and 3.5 nmol.mg-1 cell protein.min-1, about 5 times the value estimated for human liver. Cytochrome P-450 decreased in culture but it was still 20% of freshly isolated hepatocytes by Day 5 in culture. In addition, ethoxycumarin-O-deethylase and aryl hydrocarbon hydroxylase could be induced in vitro by treatment with methyl cholanthrene. Glutathione levels were similar to those reported for human liver (35 nmol.mg-1). The results of our work show that adult human hepatocytes obtained from small surgical biopsies and cultured in chemically defined conditions express their most important metabolic functions to an extent that is similar to that reported for adult human liver.