Oxidative Stress Activates Membrane Ion Channels in Human Biliary Epithelial Cancer Cells (Mz-Cha-1)

Oxidative stress is known to contribute to cell damage. In several cell types, one of the earliest effects of oxidative stress is a rapid and substantial decrease in cell volume, which in turn regulates a broad range of cell functions, including development of apoptosis. Since volume regulation is closely coupled to membrane ion permeability, activation of ion channels may play an important role in oxidative stress-related cell injury. Oxidative stress plays a major role in a variety of liver diseases and bile duct epithelia cells (BDE) represent an important site of injury. We, therefore, investigated the functional interactions of oxidative stress, cell volume and ion permeability in a BDE model. Whole-cell patch clamp studies were performed in the human Mz-Cha 1 cell line. Oxidative stress was produced by addition of H₂O₂ to the bath solution. Changes of intracellular Ca(2+) concentration and of crosssectional area (for calculating cell volume) were monitored by laser scanning microscopy. Exposure of Mz-Cha 1 cells to H₂O₂ resulted in cell shrinkage and increase of the intracellular Ca(2+) concentration. Patch-clamp studies revealed that exposure to H₂O₂ also resulted in the activation of ion currents with a threshold of 10(-6) M H₂O₂. Ion substitution studies and blocker experiments identified the currents as representing an increase in membrane K(+) and Cl-permeability. Interestingly both ion channel activation and cell shrinkage had a close relationship to the applied H₂O₂ concentration and were significantly inhibited by intracellular Ca(2+) chelation. These data imply that in a BDE model, oxidative stress leads to cell shrinkage through activation of Ca(2+)-dependent K(+) and Cl(-) currents. Since cell shrinkage has been associated with increased cell damage, the opening of these ion channels might contribute to the high susceptibility of biliary epithelial cancer cells to oxidative stress.

Sequential chemotherapies for advanced gastric cancer: a retrospective analysis of 111 patients

BACKGROUND

The role of second-line chemotherapy in advanced gastric cancer is not yet fully established.

PATIENTS AND METHODS

We analysed 111 patients with advanced gastric cancer treated at the University Hospital Heidelberg (51) and the private oncology practice Bottrop/Dorsten (60) between 2001 and 2011, comparing the outcome of patients with first-line chemotherapy and those who received second-line chemotherapy.

RESULTS

Thirty-six patients were treated with one chemotherapy regimen, 75 patients received at least two different chemotherapies. Patients who received one chemotherapy regimen were older (median age 69 years) and had a shorter overall survival (6 months) than patients receiving sequential chemotherapies [median age 61 years, p = 0.009, overall survival 14 months (2-42), p = 0.001]. Under second-line chemotherapy, partial response was observed in 25 patients (33%) and stable disease for ≥3 months in 26 patients (35%). Patients treated before 2005 had a slightly better overall survival than patients treated in or after 2005. Survival was not influenced by the treatment centre (primary or tertiary), but was influenced by former surgery.

CONCLUSION

The prognosis of advanced gastric cancer is still poor. Selected patients may benefit from individualized salvage chemotherapy after failure of first-line chemotherapy.

Extracellular ATP induces cytoplasmic and nuclear Ca2+ transients via P2Y2 receptor in human biliary epithelial cancer cells (Mz-Cha-1)

Extracellular nucleotides such as adenosine triphosphate (ATP) play a role in biliary epithelial cell function. Since nucleotide receptors are potential targets for various diseases related to epithelial cell dysfunction and cancer, the purpose of this study was to investigate the expression and to functionally characterize the nucleotide receptor subtypes in biliary epithelial cancer cells (Mz-Cha-1). Extracellular ATP dose-dependently resulted in an intracellular Ca(2+) increase (mean effective concentration (EC(50)) 40 μM). Uridine triphosphate (UTP) produced a similar Ca(2+) response and cross-desensitation was observed. The rank order of tested agonists was ATP=UTP>> adenosine>ADP=AMP>α,β-methylene-ATP. This confirms the functional expression of purinoceptor P2Y2 and P2Y4 in biliary epithelial cancer cell membranes. mRNAs for P2Y1, P2Y2, P2Y4 and P2Y6 purinergic receptor subtypes were found, whereas western blot analysis suggested only the expression of P2Y2 receptors. Confocal imaging and nuclear staining was used to compartmentalize ATP-induced cytosolic and nuclear Ca(2+)-transients, indicating a role for secretory ATP in regulating nuclear function, by increasing nuclear Ca(2+) concentrations. These data define the expression profile of P2Y receptors on human biliary epithelial cancer cells and indicate P2Y2 receptors as being potential targets in new treatment strategies for biliary cancer.

Value of lipopolysaccharide binding protein, interleukin-6 and C-reactive protein as biomarkers of severity in acute diverticulitis: a prospective study

BACKGROUND

New biomarkers have the capability to predict severity and outcome of infectious diseases. Lipopolysaccharide binding protein (LBP) and Interleukin 6 (IL-6) were determined as new markers in patients with acute diverticulitis and were compared with standard markers such as C-reactive protein (CRP) and white blood cell count (WBC).

METHODS

CRP, IL-6, WBC and LBP were measured in 38 patients at hospital admission and every second day and after colonoscopy. Multi-slice CT scans, ultrasound and early colonoscopy were performed to confirm diagnosis and to detect complications (perforations, stenosis).

RESULTS

CRP, IL-6 and LBP levels one correlated highly with each other and were equally influenced by antibiotic therapy. WBC changes were unremarkable. Severity of the disease (sealed- or non-perforation) was not reflected by the biomarkers. In non-perforated patients, colonoscopy was performed on day 6 (median) after admission with a success rate of 93%. Sealed-perforated patients were examined on median day 11 with a success rate of 60% (p > 0.001). Failure in all cases was due to sigmoidal stenosis requiring surgery. In a receiver-operating characteristic curve analysis (ROC), LBP on day one performed best in predicting colonic steno-sis with an area under the curve of 0.88 (95% CI 0.73 - 0.03 p < 0.02).

CONCLUSIONS

CRP, IL-6, and LBP can be used to monitor diverticulitis. Initial LBP values in patients with acute diverticulitis may also be usefully in detecting candidates for surgical intervention.

Adipocyte-specific inactivation of Acyl-CoA synthetase fatty acid transport protein 4 (Fatp4) in mice causes adipose hypertrophy and alterations in metabolism of complex lipids under high fat diet

Fatp4 exhibits acyl-CoA synthetase activity and is thereby able to catalyze the activation of fatty acids for further metabolism. However, its actual function in most tissues remains unresolved, and its role in cellular fatty acid uptake is still controversial. To characterize Fatp4 functions in adipocytes in vivo, we generated a mouse line with adipocyte-specific inactivation of the Fatp4 gene (Fatp4(A-/-)). Under standard conditions mutant mice showed no phenotypical aberrance. Uptake of radiolabeled palmitic and lignoceric acid into adipose tissue of Fatp4(A-/-) mice was unchanged. When exposed to a diet enriched in long chain fatty acids, Fatp4(A-/-) mice gained more body weight compared with control mice, although they were not consuming more food. Pronounced obesity was accompanied by a thicker layer of subcutaneous fat and greater adipocyte circumference, although expression of genes involved in de novo lipogenesis was not changed. However, the increase in total fat mass was contrasted by a significant decrease in various phospholipids, sphingomyelin, and cholesteryl esters in adipocytes. Livers of Fatp4-deficient animals under a high fat diet exhibited a higher degree of fatty degeneration. Nonetheless, no evidence for changes in insulin sensitivity and adipose inflammation was found. In summary, the results of this study confirm that Fatp4 is not crucial for fatty acid uptake into adipocytes. Instead, under the condition of a diet enriched in long chain fatty acids, adipocyte-specific Fatp4 deficiency results in adipose hypertrophy and profound alterations in the metabolism of complex lipids.

Lipopolysaccharide binding protein, interleukin-6 and C-reactive protein in acute gastrointestinal infections: value as biomarkers to reduce unnecessary antibiotic therapy

AIM

Several new biomarkers, such as lipopolysaccharide binding protein (LBP) and interleukin-6 (IL-6), have the potential to determine the severity and outcome of infectious diseases. LBP and IL-6 serum levels have not been reported in patients with gastrointestinal infections. The aim of this study was to compare established markers of infection with new markers, such as LBP and IL-6, in patients with acute gastrointestinal infections

METHOD

LBP, C-reactive protein (CRP), white blood cell count (WBC) and IL-6 serum levels were determined in patients with acute viral or bacterial (positive stool cultures) gastroenteritis. The final diagnosis and empiric antibiotic use were recorded. In total, medical data on 88 patients with acute gastroenteritis (22 bacterial, 66 viral or nonspecific) were analyzed.

RESULTS

LBP and CRP levels were significantly increased in patients with acute bacterial gastroenteritis [28.5 ± 16.5 vs. 15.2 ± 11.5 μg/mL (p < 0.05) and 10.4 ± 9.6 vs. 3.8 ± 5.5 mg/dL (p < 0.001), respectively]. LBP at a cut-off value of 14.6 μg/mL and CRP at a cut-off value of 1.7 mg/dL distinguished between bacterial and non-bacterial gastrointestinal infection (receiver operator characteristic analysis). Empiric antibiotic therapy was initiated in 82% of patients with bacterial gastroenteritis and in 27% of patients with viral gastroenteritis.

CONCLUSION

The use of the cut-off values for LBP and CRP determined here would have avoided unnecessary antibiotic therapy in 14 and 11%, of patients respectively. CRP and LBP appear to be superior to IL-6 and WBC as diagnostic markers of bacterial gastrointestinal infection. Cut-off values may be a useful tool to support clinical decision-making on whether or not to initiate empiric antibiotic therapy.

Oxidative stress reduces Na+/H+ exchange (NHE) activity in a biliary epithelial cancer cell line (Mz-Cha-1)

In cholangiocarcinogenesis, chronic inflammation and oxidative stress play a key role. The Na(+)/H(+) exchanger (NHE) forms a potential link between control of intra- and pericellular pH and tumor development. Therefore, the effects of oxidant stress were determined by the use of tert-butyl hydroperoxide (t-BOOH) on Na(+)/H(+) exchange in a biliary epithelial cancer cell line (Mz-Cha-1). The cells were exposed to the hydroperoxide and the rate of recovery from acidosis was determined by the use of the pH-sensitive fluorochrome 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester (BCECF/AM). t-BOOH reduced Na(+)/H(+) exchange activity in a dose-dependent manner. At 4 mM t-BOOH, Na(+)/H(+) exchange activity was virtually absent. This was accompanied by an increase in cytotoxicity (MTT assay). Glutathione repletion and intracellular Ca(++) chelation partially restored the Na(+)/H(+) exchange activity. Hydroperoxide seemed neither to alter the intracellular signal transduction pathways (cAMP and Ca(++) oscillations) nor the membrane distribution of the exchanger (immunostaining). Decrease in Na(+)/H(+) exchange activity in this model of oxidant stress may represent an early perturbation of membrane function, and the functional integrity of Na(+)/H(+) exchange could therefore be dependent on the glutathione redox system.

Gamma-hydroxybutyric acid versus clomethiazole for the treatment of alcohol withdrawal syndrome in a medical intensive care unit: an open, single-center randomized study

BACKGROUND

Clomethiazole (CLO) has been shown to be effective in treating alcohol withdrawal syndrome (AWS). Gamma-Hydroxybutyric acid (GHB) has also been introduced in the treatment of alcoholic patients and is effective in surgical intensive care unit (ICU) patients in preventing and treating AWS. There are no comparative studies between CLO and GHB in a medical ICU setting.

METHODS

Twenty-six alcoholic patients with severe AWS and concomitant medical diseases were randomally enrolled in the study. CLO was given orally to 12 patients in a dosage of 250 mg every 4 hours as a liquid; GHB (initially 30 mg/kg body weight (BW) followed by 15 mg/kg BW) was administered intravenously to 14 patients. Four major AWS symptoms (tremor, sweating, nausea, restlessness) were scored, and the administration of additional medication was registered.

RESULTS

GHB was more effective in treating AWS symptoms. In the GHB group, AWS score dropped from 6.6 +/- 2.6 to 1.8 +/- 2.1 (p <.01), while in the CLO group, the score dropped from 6 +/- 2.5 to 4.1 +/- 2.4 (n. s.). Differences between groups were significant (p =.021, two-way ANOVA). The treatment did not alter outcome or the duration of ICU stay. No serious side effects were detected.

CONCLUSION

GHB effectively controls AWS symptoms in medical ICU patients. The rapid initial treatment response of GHB in contrast to CLO has no influence on duration of patient withdrawal.

Risk factors for colonic diverticular bleeding: A Westernized community based hospital study

AIM: To evaluate the risk factors-other than nonsteroidal anti-inflammatory drugs-for colonic diverticular bleeding in a westernized population.

METHODS: One hundred and forty patients, treated for symptomatic diverticular disease in a community based hospital, were included. Thirty (21%) had signs of diverticular bleeding. Age, gender, and the results of colonoscopy were collected and compared to a group of patients with nonbleeding symptomatic diverticulosis. Records were reviewed for comorbidities, such as obesity, alcohol consumption, smoking habits and metabolic diseases. Special emphasis was put on arterial hypertension, cardiovascular events, diabetes mellitus, hyperuricemia and hypercholesterinemia.

RESULTS: There was no difference between patients with diverticular hemorrhage and those with nonbleeding symptomatic diverticulosis regarding gender ratio (male/female 9/21 vs 47/63) and diverticular localisation. Bleeding patients differed in respect to age (73.4 ± 9.9 vs 67. 8 ± 13.0, P < 0.013). Significant differences were found between both groups regarding the presence of hyperuricemia and use of steroids and nonsteroidal anti-inflammatory drugs. Patients with three concomitant metabolic diseases were also identified as being at risk of bleeding. A forward stepwise logistic regression analysis revealed steroids, hyperuricemia and the use of calcium-channel blockers as independent risk factors of bleeding.

CONCLUSION: Beside nonsteroidal anti-inflammatory steroid drug use, antihypertensive medication and concomitant arteriosclerotic diseases are risk factors for colonic diverticular hemorrhage. Our results support the hypothesis of an altered arteriosclerotic vessel as the source of bleeding.

Alcohol binging causes peliosis hepatis during azathioprine therapy in Crohn's disease

Patients with inflammatory bowel disease have normal life expectancy and, due to modern immunosuppressive therapies, also a normal quality of life. Since mostly young people are affected, their social behaviour suits this environment. Alcohol binging is an increasingly disturbing factor among young people. We describe a patient with Crohn’s disease, treated with azathioprine, who developed peliosis hepatis after three epsiodes of alcohol binging. Liver toxicity was not observed previously during the course of the treatment. Azathioprine-induced peliosis hepatis is thought to be idiosyncratic in humans. From animal studies, however, it is clear that hepatic depletion of glutathione leads to azathioprine toxicity to the sinusoidal endothelial cells. Damage of these cells causes peliosis hepatis. Since alcohol binging leads to hepatic glutathione depletion, we conclude that in our patient the episodes of binging have reduced liver gluathione content and therefore this has increased azathioprine toxicity causing peliosis hepatis. The problem of alcohol binging has not yet been addressed in IBD patients undertaking immunosuppressive therapy. This should be reviewed in future considerations regarding patients advice.

Mechanisms of hypotonic inhibition of the sodium, proton exchanger type 1 (NHE1) in a biliary epithelial cell line (Mz-Cha-1)

AIM

To elucidate the cellular events that results in inhibition of Na(+), H(+) exchanger type 1 (NHE1) by hypotonicity.

METHODS

Intracellular pH (pH(i)) was measured in biliary epithelial cells, with the pH-sensitive fluorochrome 2',7'-bis-(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) using a spectrophotometer. Regulatory volume decrease (RVD) was analysed from confocal images. Changes in NHE1 membrane content were visualized by confocal laser scanning microscopy after transfection of Mz-Cha-1 cells with a NHE1-cMyc fusion protein.

RESULTS

In Mz-Cha-1 cells hypotonicity (-80 mmol L(-1) NaCl) inhibited endogenous Na(+), H(+) exchange. Tyrosine and serine kinase inhibitors were incapable to prevent inhibition. As several signalling pathways influence Na(+), H(+) exchange, we tested the effect of the Ca(++), Calmodulin, protein kinase C or the cAMP, protein kinase A system on inhibition of Na(+), H(+) exchange by hypotonic challenge, but neither system was involved. In contrast, cytoskeleton did influence the effect of hypotonicity. Inhibition of microtubule polymerization by colchicine prevented inhibition of NHE1, and also restored Na(+), H(+) exchange kinetics. Specific inhibition of Src kinases with PP2, attenuated pH(i) recovery rate from 1.93 +/- 0.16 pH units min(-1) (normotonic environment) to 1.02 +/- 0.50 pH units min(-1) (hypotonic environment). Membrane staining of NHE1-cMyc fusion protein was maintained after hypotonic exposure in colchicine pre-treated cells as was RVD. Microfilament inhibition by cytochalasin preserved NHE1 activity. Inhibition of phosphatidylinositol-3'-kinase was unable to restore Na(+), H(+) exchange activity.

CONCLUSION

We conclude that regulation of Na(+), H(+) exchange during RVD is mediated by cytoskeletal elements. This receptor independent pathway is regulated by Src.

Budesonide for the treatment of obstructive eosinophilic jejunitis

Eosinophilic gastroenteritis is a rare gastrointestinal (GI) disorder of undetermined origin, characterized by infiltration of eosinophils in the GI tract. Different layers of the bowel wall can be involved and the clinical outlook depends on the area affected. Our subject is a male patient in whom the disease involves the muscular layer causing obstructive jejunitis. The diagnosis was made after surgical resection. A relapse was subsequently treated with short-term intravenous steroids followed by oral budesonide for three months. Treatment was effective with no apparent side effects.

Serum levels of soluble Fas, nitric oxide and cytokines in acute decompensated cirrhotic patients

AIM: To evaluate plasma levels of nitrite/nitrate (NOx), soluble Fas (sFas) antigen, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in patients with compensated and acute decompensated cirrhosis and to evaluate mediators causing acute decompensation in liver cirrhosis.

METHODS: This prospective study was conducted in the medical intensive care unit of an academic tertiary center. Fifty-five patients with acute decompensation (gastrointestinal hemorrhage, encephalopathy, hydropic decompensation) and twenty-five patients with compensated liver cirrhosis were included. Blood samples were taken for analyses of sFas, Nox, IL-6, TNF-α. Liver enzymes and kidney functions were also tested.

RESULTS: In patients with acute decompensation, plasma sFas levels were higher than in non-decompensated patients (15 305 ± 4646 vs 12 458 ± 4322 pg/mL, P < 0.05). This was also true for the subgroup of patients with alcoholic liver cirrhosis (P < 0.05). The other mediators were not different and none of the parameters predicted survival, except for ALT (alanine-aminotransferase). In patients with portal-hypertension-induced acute hemorrhage, NOx levels were significantly lower than in patients with other forms of decompensation (70.8 ± 48.3 vs 112.9 ± 74.9 pg/mL, P < 0.05). When NOx levels were normalized to creatinine levels, the difference disappeared. IL-6, TNF-α and sFas were not different between bleeders and non-bleeders. In decompensated patients sFas, IL-6 and NOx levels correlated positively with creatinine levels, while IL-6 levels were dependent on Child class.

CONCLUSION: In acute decompensated cirrhotic patients sFas is increased, suggesting a role of apoptosis in this process and patients with acute bleeding have lower NOx levels. However, in this acute complex clinical situation, kidney function seems to have a predominant influence on mediator levels.

Ulcerative jejunoileitis and enteropathy-associated T-cell lymphoma

Ulcerative jejunoileitis and enteropathy-associated T-cell lymphoma are rare conditions described in patients with refractory coeliac disease. Ulcerations affect the small bowel and are unrelated to drugs, ischaemia, infections or other known causes. We describe a female patient with an unclassified enteropathy who experienced several episodes of jejunoileal ulcerations. Several resections of the small bowel segments were necessary. The repetitive ulcerations were either from cytotoxic T cells, the patient developed a T-cell lymphoma, and malignant cells could be detected at the bottom of the ulcers, or from acid-producing cells in areas of gastric metaplasia. Two mechanisms might thus be responsible for the occurrence of repetitive ulceration, and require different treatment strategies. The patient is currently being treated with proton pump inhibitors, oral steroids and parenteral nutrition.

Progressive sclerosing cholangitis after septic shock: a new variant of vanishing bile duct disorders

BACKGROUND

We present nine patients with progressive sclerosing cholangitis after septic shock.

PATIENTS

All nine patients had previously required long term treatment in an intensive care unit for septic shock: two patients with polytrauma, five with burn injury, and two with extensive surgery. They were admitted to our hospital because of cholangitis. Endoscopic retrograde cholangiography revealed severe intrahepatic stenoses in all patients and liver biopsies showed typical signs of sclerosing cholangitis. No patient had pre-existing liver disease.

RESULTS

Mean follow up time was 35 months. In patients with major bile duct stenoses (3/9), 12 endoscopic dilations were performed in total. In one patient, concrements were extracted and intermittent stenting was necessary. To date, 4/9 patients have rapidly developed liver cirrhosis. During follow up, 5/9 patients died: two after fulminant cholangitis, one after liver failure, one due to liver transplantation associated problems, and one after cerebral ischaemia. One patient has been registered for transplantation and the remaining three patients show no acute signs of liver failure.

CONCLUSIONS

Patients with sclerosing cholangitis, following septic shock, represent a new variant of vanishing bile duct disorders. In such patients liver disease rapidly progresses to cirrhosis. Endoscopic treatment may only transiently improve the course of the disease. Orthotopic liver transplantation is indicated in end stage disease.

Procalcitonin is a valid marker of infection in decompensated cirrhosis

BACKGROUND/AIMS

Bacterial infections are life-threatening complications in cirrhosis and early diagnosis is mandatory. Procalcitonin, a 116 amino acid propeptide of calcitonin, is an early marker of infection. The aim was to evaluate prospectively procalcitonin in the diagnosis of bacterial infection in cirrhosis. 127 patients with liver cirrhosis were analysed and stratified into three groups according bacteriological and morphological findings; decompensated patients with (group I = 36) and without (group II = 64) infection, and 27 non-decompensated and non-infected (group III).

METHODS

Diagnosis of infection was made using standard criteria. Serum procalcitonin, tumour necrosis factor alpha, interleukin-6 and C-reactive protein were measured using commercially available methods.

RESULTS

PCT serum levels were significantly different between group I (2.8 ng/ml [0.4 - 20.4]), group II (0.6 ng/ml [0.1 - 5.9]) and group III (0.4 ng/ml [0.1 - 1.2]), respectively. Levels above 0.58 ng/ml had a sensitivity of 92 % and specificity of 78 % for the diagnosis of infection and were associated with a 50 % mortality in the first two months. Interleukin-6, tumour necrosis factor alpha and C-reactive protein were less sensitive and specific for the diagnosis of infection.

CONCLUSION

In decompensated cirrhosis procalcitonin serum levels provided the most sensitive and specific tool for the initial diagnosis of bacterial infection.

[MRI in chronic inflammatory bowel disease]

Chronic inflammatory bowel disease is diagnosed and monitored by the combination of colonoscopy and small bowel enteroklysis. Magnetic resonance imaging has become the gold standard for the imaging of perirectal and pelvic fistulas. With the advent of ultrafast MRI small and large bowel imaging has become highly attractive and is being advocated more and more in the diagnostic work up of inflammatory bowel disease. Imaging protocols include fast T1-weighted gradient echo and T2-weighted TSE sequences and oral or rectal bowel distension. Furthermore, dedicated imaging protocols are based on breath-hold imaging under pharmacological bowel paralysis and gastrointestinal MR contrast agents (Hydro-MRI). High diagnostic accuracy can be achieved in Crohn's disease with special reference to the pattern of disease, depth of inflammation, mesenteric reaction, sinus tract depiction and formation of abscess. In ulcerative colitis, the mucosa-related inflammation causes significantly less bowel wall thickening compared to Crohn's disease. Therefore with MRI, the extent of inflammatory changes is always underestimated compared to colonoscopy. According to our experience in more than 200 patients as well as the results in other centers, Hydro-MRI possesses the potential to replace enteroklysis in the diagnosis of chronic inflammatory bowel disease and most of the follow-up colonoscopies in Crohn's disease. Further technical improvements in 3D imaging will allow interactive postprocessing of the MR data.

Endothelin-1 and smooth muscle cells: induction of jun amino-terminal kinase through an oxygen radical-sensitive mechanism

Endothelin-1 (ET-1) has been proposed to contribute to atherogenesis and plaque rupture in coronary heart disease through activation of mitogen-activated protein kinases (MAPKs) in smooth muscle cells (SMCs). Reactive oxygen species (ROS) have been shown to be important signal transduction molecules in SMCs. Thus, the present study aimed to assess the role of ROS in ET-1-mediated activation of c-Jun amino-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) 1/2. Rat SMCs were exposed to ET-1 over time at concentrations from 10(-6) to 10(-10) mol/L, and MAPK activity was quantified. Activation of JNK and ERK was observed with a maximum stimulation at 10(-7) mol/L ET-1. JNK and ERK were activated by ET-1 binding to a single receptor (ET-1A) but differed in their downstream mechanisms: only JNK activation was sensitive to the radical scavenger N-acetylcysteine and diphenylene iodonium, an inhibitor of NADPH oxidase, indicating a role for ROS. The downstream MAPK effector and proinflammatory transcription factor, the activator protein-1 complex, was maximally activated 2 hours after the addition of ET-1. It was mainly composed of the JNK substrate c-Jun, and activation was also dependent on ROS formation. We suggest that plaque activation by ET-1 can be mediated through ROS. It can be hypothesized that the clinical benefit of antioxidants in the treatment of atherogenesis may partially depend on neutralization of ET-1-mediated ROS production.

Differential activation of mitogen-activated protein kinases in smooth muscle cells by angiotensin II: involvement of p22phox and reactive oxygen species

The atherogenic effect of the renin-angiotensin system can be explained, in part, by the influence of its effector, angiotensin II (Ang II), on vascular smooth muscle cell (VSMC) growth. There is evidence that reactive oxygen species (ROS) play a role in the atherogenesis and activation of mitogen-activating protein (MAP) kinases, which are involved in proliferation and differentiation. The study was performed to further characterize the role of ROS in Ang II-mediated MAP kinase activation and the regulation of the transcription factor activator protein-1 (AP-1). Rat VSMCs were stimulated with Ang II. The activities of MAP kinases were assessed by Western blot analysis or by immunocomplex kinase assay. AP-1 binding was determined by using an electrophoretic mobility shift assay. Rat VSMCs were treated with Ang II-activated MAP kinases, extracellular signal-regulated kinase (ERK), c-Jun amino terminal kinase (JNK), p38 MAP kinase (p38 MAPK), and their downstream effector, AP-1. Interestingly, only the activation of ERK1/2, but not JNK or p38 MAPK, was tyrosine kinase, protein kinase C, and MEK1/2 dependent. Ang II also induced the rapid formation of ROS, which could be inhibited by a specific antibody as well as by antisense against the p22phox subunit of the NAD(P)H oxidase. JNK and p38 MAPK, but not ERK, activation was inhibited by an inhibitor of NAD(P)H oxidase. Antisense against p22phox also solely inhibited p38 MAPK but did not affect ERK. The results indicate that in VSMCs, Ang II activates MAP kinases and AP-1 through different pathways; the results further suggest that ROS, generated by p22phox, mediate Ang II-induced JNK and p38 MAPK activation, which may contribute to the pathogenesis of atherosclerosis.

Sodium, hydrogen exchange type 1 and bile ductular secretory activity in the guinea pig

Biliary epithelial cells (BECs) express different Na(+), H(+) exchange (NHE) isoforms. In this study, the potential role of NHE in ductular bile secretion is assessed. Experiments were performed in guinea pig perfused livers and isolated BECs. Inhibition of NHE was achieved by hypotonic stress and by using the unspecific NHE inhibitor, amiloride, or the specific NHE 1 inhibitor, cariporide (HOE 642). Hypotonic stress inhibited basal bile flow by 46% and prevented secretin stimulation of bile flow by reducing biliary bicarbonate output by 50%. Secretin increased bile flow from 3.7 +/- 0.8 microL/min/g to 4.78 microL/min/g (P <.01); subsequent exposure to hypotonic stress decreased secretin-stimulated bile flow by 35% and biliary bicarbonate secretion by approximately 50%. Inhibition of NHE by amiloride or cariporide resulted in a similar reduction of secretin-stimulated bile flow and bicarbonate secretion. Basal bile flow was unaffected by the NHE inhibitors. In isolated guinea pig BECs, regulatory volume decrease and inhibition of NHE was demonstrated after hypotonic stress under basal and secretin-stimulated conditions. In contrast, hypotonic exposure inhibited Cl(-), HCO(3)(-) exchange activity in isolated BECs only during basal conditions but incompletely after secretin stimulation. Our study shows that hypotonic stress inhibits basal bile flow in the guinea pig by inhibition of Cl(-), HCO(3)(-) exchange. NHE1 is not involved in basal bile formation. Increased choleresis after ductular stimulation by secretin depends on intact NHE1 activity. These data indicate that BEC volume changes have profound effects on biliary secretory function.

Expression of a bile acid transporter in biliary epithelial cells from normal and cholestatic rat livers

A sodium dependent bile acid carrier has recently been cloned and characterized in rat ileum. The present study demonstrates the presence of a mRNA species specific for the rat ileal bile acid carrier (r-IBAT) in rat biliary epithelial cells. Moreover, immunohistochemistry with a peptide specific antibody demonstrates protein expression in biliary epithelial cells from normal and bile duct ligated rat livers. Besides a cytoplasmic staining a predominant staining of the apical membrane could be observed. These observations indicate that biliary epithelial cells are involved in bile acid transport across the biliary tree. In addition the carrier could also play a role in the signal transduction of bile acid induced ductular secretion.

Electrogenicity of hepatocellular fatty acid uptake

Sensitivity of cellular fatty acids uptake to the membrane potential difference is still a matter of controversy. For direct evaluation of potential sensitivity the effect of changing membrane potential on uptake of a fluorescent long chain fatty acid derivative, 12-NBD-stearate, in isolated rat hepatocytes, was examined. Changes in membrane potential were achieved by patch clamp procedures. Fatty acid influx was simultaneously determined by recording of cell fluorescence. Hyperpolarization from -30 to -70 mV accelerated fatty acid influx whereas depolarization to +50 mV reduced uptake. After obtaining equilibrium hyperpolarization increased cell fluorescence, whereas depolarization pushed NBD-stearate out of cells. Potential sensitivity of uptake was dependent on the fatty acid concentrations in the medium with most prominent effects at low unbound concentrations. These data show that, at low fatty acid concentrations, uptake is, in part, driven by an intracellular negative electric membrane potential.

Long-chain fatty acid uptake by skeletal myocytes: a confocal laser scanning microscopy study

Studies of regulation of free fatty acid (FFA) utilization by skeletal muscles have focused on plasma FFA delivery and on intracellular factors affecting FFA metabolism. The present study was conducted to directly analyse the uptake process of fatty acids into single myocytes. Cells were isolated from the rat flexor digitorum brevis muscle. Confocal laser scanning microscopy was utilized to analyse the uptake of the fluorescent fatty acid derivative 12-NBD-stearate, which is not metabolized by muscle tissue. Uptake represented a saturable function of the unbound fatty acid concentration in the medium (K(m) 366 +/- 118 nM, Vmax 2.1 +/- 0.3 AU/s) and depended on the medium sodium concentration. Reduced buffer pH increased initial uptake rates, whereas lactate (10 mM) had no effect. Membrane hyper- and depolarization decreased uptake rates. This study demonstrates for the first time kinetic data from isolated myocytes with evidence for a carrier-mediated transport mechanism for long-chain fatty acids.

Effect of ethanol and fructose on liver metabolism: a dynamic 31Phosphorus magnetic resonance spectroscopy study in normal volunteers

In vivo 31Phosphorus magnetic resonance spectroscopy (31P-MRS) permits evaluation of dynamic changes of individual phosphorus-containing metabolites in the liver parenchyma, such as phosphomonoester (PME), adenosine triphosphate, and inorganic phosphate (Pi). Intravenous fructose load alters phosphorus metabolites and allows assessment of liver function by 31P-MRS. 31P-MRS data obtained in alcoholic liver disease are however inconclusive. To study the hypothesis that fructose load can be used to investigate metabolic effects of ethanol ingestion, the interaction of different metabolites--i.e., fructose and ethanol--were followed in vivo. Using a 1.5 Tesla magnetic resonance system, six healthy volunteers were examined in three sessions each: a session after administration of (a) fructose only (250 mg/kg) was compared with (b) fructose load after ethanol ingestion (0.8 g/kg). A control experiment (c) was done after ethanol only. Spectra were acquired using one-dimensional chemical shift imaging with a temporal resolution of 5 min. Following a fructose load, the concomitant uptake of ethanol showed drastic changes of individual metabolic steps of the hepatic metabolism (averages +/- standard deviation). While the velocity of the net formation of PME (relative increase 0.46 +/- 0.11 without ethanol vs. 0.61 +/- 0.25 with ethanol) and the use of adenosine triphosphate (-0.13 +/- 0.03 vs. -0.16 +/- 0.03) and Pi (-0.022 +/- 0.009 vs. -0.021 +/- 0.004) were not significantly affected by ethanol uptake, a significant (p < 0.01) reduction of PME degradation (31.3 +/- 9.4 vs. 61.9 +/- 16.9 relative total area) and absence of an overshoot for Pi (10.5 +/- 4.9 vs. -7.1 +/- 5.3 relative area 13 min to 43 min) was observed after ethanol administration. Dynamic 31P-MRS allows the observation of individual steps of hepatic metabolism in situ; fructose metabolism in the human liver is slowed down by concomitant ethanol ingestion after the phosphorylation step of fructose. This could be explained by inhibition of aldolase rather than ethanol-induced changes of the hepatic redox state. Fructose load can be used to study effects of alcohol ingestion and might therefore be useful in patients with alcoholic liver disease.

Muscarinic acetylcholine receptor stimulation of biliary epithelial cells and its effect on bile secretion in the isolated perfused liver [corrected]

The aim was to explore whether biliary epithelial cells show muscarinic acetylcholine receptors and to investigate their role in ductular bile formation. In both, isolated rat biliary epithelial cells and Mz-Cha-1 cells, a biliary epithelial cell line, binding of [3H]N-methyl-scopolamine occurred with 0.718 +/- 0.08 and 0.482 +/- 0.05 fmol per 10(6) cells, respectively. To characterize the involved second messenger, intracellular Ca2+ levels were monitored by confocal microscopy. Stimulation of biliary epithelial cells with carbachol produced an increase in free cytosolic Ca2+ levels that declined to baseline values describing a sinusoidal oscillation curve. Increasing concentrations of the agonist decreased latency of the response and increased oscillation frequency. Similar results were obtained in Mz-Cha-1 cells. The intracellular Ca2+ originated from IP3 sensitive intracellular stores and from the extracellular medium. The Ca2+ response could partially be blocked by atropine and completely by pirenzepine, a specific muscarinic receptor-type M1 antagonist. The presence of M1 receptor messenger RNA (mRNA) in biliary epithelial cells was confirmed by reverse transcriptase polymerase chain reaction. In the isolated perfused guinea pig liver, a model with high ductular bile flow, carbachol induced a dose dependent decrease of bile flow by 79.6% +/- 9.8% at 50 mumol/L carbachol (P < .001), without affecting perfusion pressure or biliary electrolyte concentrations. It is concluded that biliary epithelial cells express muscarinic acetylcholine receptors. Stimulation of this receptor leads to cholestasis. This could be because of changes in peribiliary permeability and/or inhibition of biliary epithelial cell secretory function.

Effect of surface and intracellular pH on hepatocellular fatty acid uptake

Fatty acids enter hepatocytes, at least in part, by a carrier-mediated uptake mechanism. The importance of driving forces for fatty acid uptake is still controversial. To evaluate possible driving mechanisms for fatty acid transport across plasma membranes, we examined the role of transmembrane proton gradients on fatty acid influx in primary cultured rat hepatocytes. After hepatocytes were loaded with SNARF-1 acetoxymethyl ester, changes in intracellular pH (pHi) under different experimental conditions were measured and recorded by confocal laser scanning microscopy. Fatty acid transport was increased by 45% during cellular alkalosis, achieved by adding 20 mM NH4Cl to the medium, and a concomitant paracellular acidification was observed. Fatty acid uptake was decreased by 30% during cellular acidosis after withdrawal of NH4Cl from the medium. Cellular acidosis activates the Na+/H+ antiporter to export excessive protons to the outer cell surface. Inhibition of Na+/H+ antiporter activity by amiloride diminishes pHi recovery and thereby accumulation of protons at the outer surface of the plasma membrane. Under these conditions, fatty acid uptake was further inhibited by 57% of control conditions. This suggests stimulation of fatty acid influx by an inwardly directed proton gradient. The accelerating effect of protons at the outer surface of the plasma membrane was confirmed by studies in which pH of the medium was varied at constant pHi. Significantly higher fatty acid influx rates were observed at low buffer pH. Recorded differences in fatty acid uptake appeared to be independent of changes in membrane potential, because BaCl2 did not influence initial uptake velocity during cellular alkalosis and paracellular acidosis. Moreover, addition of oleate-albumin mixtures to the NH4Cl incubation buffer did not change the observed intracellular alkalinization. In contrast, after cells were acid loaded, addition of oleate-albumin solutions to the recovery buffer increased pHi recovery rates from 0.21 +/- 0.02 to 0.36 +/- 0.05 pH units/min (P < 0.05), indicating that fatty acids further stimulate Na+/H+ antiporter activity during pHi recovery from an acid load. It is concluded that carrier-mediated uptake of fatty acids in hepatocytes follows an inwardly directed transmembrane proton gradient and is stimulated by the presence of H+ at the outer surface of the plasma membrane.

The plasma borne free fatty acids rapidly enter the hepatocellular nuclei

Long-chain free fatty acids (FA) were shown to exert a regulatory function in the nucleus. However, the route of their entry remains uncertain. The aim of the present study was to examine whether the extracellular FA enter the hepatocellular nuclei. The experiments were carried out in vivo and in vitro. Intravenous administration of albumin-bound [14C]-palmitic and [14C]-linoleic acid resulted in rapid accumulation of the labels in the nuclear lipids. Unesterified [14C]-palmitic acid represented 22.4 +/- 1.7 and [14C]-linoleic acid 17.6 +/- 1.3 percent of the total lipid radioactivity. In vitro, confocal laser scanning microscopy was used to examine 12-NBD-stearate (a fluorescent derivative of stearate) translocation into the nuclei of isolated hepatocytes. It was found that 12-NBD stearate enters the nucleus and that this uptake depends on the extracellular and/or cytoplasmic concentration. It is concluded that factors (e.g. dietary) leading to alterations in the plasma FA composition and content can result in rapid changes of the nuclear FA pool and thus regulate certain nuclear processes.

Sodium, hydrogen antiporter activation by extracellular adenosine triphosphate in biliary epithelial cells

BACKGROUND & AIMS

Extracellular nucleotides are secretagogues and influence ion permeability. The aim of this study was to investigate whether secretagogues activate transmembrane acid-base carriers, e.g., sodium, hydrogen antiporter in cholangiocytes.

METHODS

Cells were loaded with pH and Ca(2+)-sensitive dyes. Intracellular changes in ion concentrations were monitored by confocal laser scanning microscopy. Adenosine 3', 5'-cyclic monophosphate was determined by standard methods.

RESULTS

Baseline intracellular pH (pH1) averaged 7.28 +/- 0.17 pH units. Adenosine triphosphate (ATP; 10 mumol/L) increased baseline pH1 by 0.28 +/- 0.06 pH units/10 min (P < 0.01). Ten and 100 mumol/L ATP increased Na+, H+ antiporter-mediated proton flux from 9.4 +/- 4.9 mmol. L-1 min-1 to 17.2 +/- 11.8 and 16.7 +/- 10.3 mmol. L(-1)-min(-1) (P < 0.001), respectively. Under control and ATP-stimulated conditions, 1 mmol/L amiloride blocked pH1 recovery, indicating true activation of Na+, H+ antiporter by extracellular ATP. Inhibition of basolateral Na+, H+ antiporter isoform inhibited stimulation by ATP. Na+, H+ antiporter-mediated proton flux was stimulated by adenosine, uridine triphosphate, adenosine-5'-0-(3-thiotriphosphate), alpha, beta-methylene-ATP, and 2-methylthio-ATP but not prevented by adenosine receptor blocking. Activation by ATP was not influenced by the Ca2+/protein kinase C/calmodulin system but could be mimicked by addition of N6,2'-O-dibutyryladenosine-3',5'-cyclic monophosphate and was inhibited by pertussis toxin.

CONCLUSIONS

Extracellular nucleotides may modulate secretory and absorptive function of cholangiocytes by activating Na+/H+ exchange mechanisms.

Rapid onset of apoptosis in vitro follows disruption of beta 1-integrin/matrix interactions in human colonic crypt cells

BACKGROUND & AIMS

Apoptosis by loss of adherence is a recently described phenomenon termed "anoikis." beta 1, integrins are heterodimeric surface molecules mediating adhesion to the extracellular matrix. The aim of this study was to address whether anoikis accounts for the elimination of senescent enterocytes and, if so, whether beta 1 integrins are involved.

METHODS

Whole crypts were isolated from normal human colonic mucosa and examined in vitro.

RESULTS

The vast majority of cells in resuspended crypts rapidly underwent apoptosis within 4 hours. Apoptosis was partially inhibited when cells had contact with collagen I-coated membranes or when whole crypts were embedded in a collagen gel. Preincubation of crypts with an inhibiting anti-beta 1 antibody before readhesion caused a much higher apoptotic rate. Confocal microscopy of embedded crypts revealed two critical zones of high sensitivity to temporary loss of adherence: the base of the crypts where stem cells are supposed to reside and the crypt mouth including the surface epithelium.

CONCLUSIONS

Survival of colonic epithelia crucially depends on matrix adhesion and is likely to be guaranteed by beta 1-integrin/ matrix interaction. The data strongly suggest that anoikis is the way senescent colon cells die.

Differential expression of Na+,H(+)-antiporter mRNA in biliary epithelial cells and in hepatocytes

BACKGROUND/AIMS

Amiloride inhibitable Na+,H(+)-exchange has recently been identified and characterized in rat biliary epithelial cells where its activity at low intracellular pH is significantly higher than in hepatocytes.

METHODS

Northern blot and reverse transcription-polymerase chain reaction were used to study the expression of the different Na+,H(+)-antiporter isoforms in isolated biliary epithelial cells and hepatocytes.

RESULTS

The present study demonstrates for the first time the expression of Na+,H(+)-antiporter isoform 1 mRNA in rat biliary epithelial cells. Moreover, steady-state levels of this message were several-fold higher in biliary epithelial cells than in hepatocytes. In addition, the expression of Na+,H(+)-antiporter isoform 2 in bile duct epithelial cell but not hepatocytes could be demonstrated by reverse transcription-polymerase chain reaction.

CONCLUSIONS

The higher expression of Na+,H(+)-antiporter isoform 1 mRNA may indicate a higher rate of synthesis and therefore a higher Na+,H(+)-exchange activity in biliary epithelial cells than in hepatocytes and is entirely compatible with the results of the previous functional studies.

Absorptive and secretory mechanisms in biliary epithelial cells

Biliary epithelial cells line the intra- and extrahepatic biliary tree. They are involved in bile formation and are of importance in different cholestatic conditions (vanishing bile duct syndrome). In recent years, progress has been made to elucidate more precisely the physiological role of biliary epithelial cells. Biliary epithelial cells are involved in the cholehepatic shunting of bile acids, they reabsorb sugar and glutamate from bile. Secretin-induced electrolyte secretion is regulated by intracellular cAMP levels in these cells. Intracellular Ca2+ levels, which are increased by different agonists, e.g. carbachol, regulate transmembrane ion channels. ATP acts as secretagogue in these cells by activating ion channels and Na+, H+ antiporter. Further studies have to investigate in which parts of the biliary tree absorptive or secretory mechanisms are predominant.

Confocal analysis of hepatocellular long-chain fatty acid uptake

Transmembrane transport and cytosolic accumulation of fatty acids were investigated using confocal laser scanning microscopy (cLSM). A Zeiss LSM 310 system was used to determine the uptake of the fluorescent fatty acid derivative 12-(N-methyl)-N-[(7-nitrobenz-2-oxa-1,3- diazol-4-yl)amino]octadecanoic acid (12-NBD stearate) (C18) in single rat hepatocytes. Uptake was a saturable process with a Michaelis-Menten constant value of 68 nM. Initial uptake velocity was dependent on extracellular presence of albumin and beta-lactoglobulin. Absence of albumin reduced uptake to 32 +/- 16% (P < 0.01) of control values. In the presence of unlabeled stearate, uptake of 12-NBD stearate was lowered to 49 +/- 12% (P < 0.01). Ion substitution experiments showed no sodium dependency of uptake. Increase in membrane potential led to a pronounced accumulation of the fatty acid derivative within the plasma membrane and in the adjacent cytoplasmic compartment, whereas membrane depolarization had no effect on uptake rates. In separate experiments line scans through representative hepatocytes were analyzed to generate "x-t" plots. 12-NBD stearate showed a fluorescence pattern with prominent staining of the area of the plasma membrane and the adjacent cytoplasm, dependent on the presence of extracellular albumin. For the hepatocellular cytosolic accumulation process of 12-NBD stearate a diffusion constant of 22.2 +/- 6.2 x 10(-9) cm2/s was calculated. In contrast to the long-chain fatty acid derivative 12-NBD stearate, short (C5)- and medium (C11)-chain fatty acids revealed no membrane interaction with hepatocytes. Erythrocytes also lacked a membrane interaction process for 12-NBD stearate. In conclusion, it was demonstrated that cLSM is capable of directly evaluating the cellular fatty acid uptake process at a subcellular level.

Solvent isotope effect on bile formation in the rat

2H2O affects many membrane transport processes by solvent and kinetic isotope effects. Since bile formation is a process of osmotic filtration where such effects could be important, we investigated the effects of 2H2O on bile formation in the in situ perfused rat liver. Dose finding experiments showed that at high concentrations, 2H2O increased vascular resistance and induced cholestasis; at 60% 2H2O however, a clear dissociation between the vascular and biliary effects was observed. Therefore, further experiments were carried out at this concentration. The main finding was a reduction in bile salt-independent bile flow from 0.99 +/- 0.04 to 0.66 +/- 0.04 microliters.min-1.g-1 (P < 0.001). This was associated with a 40% reduction in biliary bicarbonate concentration (P < 0.001). Choleretic response to neither taurocholate nor ursodeoxycholate was altered by 2H2O; in particular, there was a similar stimulation of bicarbonate secretion by ursodeoxycholate in the presence of 60% 2H2O. To further elucidate this phenomenon, the effect of 2H2O on three proteins potentially involved in biliary bicarbonate secretion was studied in vitro. 2H2O slightly inhibited cytosolic carboanhydrase and leukocyte Na+/H(+)-exchange, these effects reached statistical significance at 100% 2H2O only, however. In contrast, Cl-/HCO(3-)-exchange in canalicular membrane vesicles was already inhibited by 50% (P < 0.001) at 60% 2H2O. Finally, there was a slight reduction in biliary glutathione secretion while that of the disulphide was not affected. Our results are compatible with an inhibition of canalicular Cl-/HCO(3-)-exchange by 2H2O. Whether this is due to altered hydration of the exchanger and/or of the transported bicarbonate remains to be determined.

Ursodeoxycholate-induced hypercholeresis in cirrhotic rats: further evidence for cholehepatic shunting

The aim of the investigation was to explore whether ursodeoxycholate, a tertiary bile acid with potential for treatment of chronic cholestasis in cirrhotic liver disease, has the same physiological effects in cirrhotic as in normal rats. Furthermore, we wanted to investigate whether ductular proliferation, as it occurred in this situation, increases the bicarbonate stimulatory effect of ursodeoxycholate. Rats (n = 16) were rendered cirrhotic by continuous exposure to phenobarbital-carbon tetrachloride; untreated animals (n = 13) served as controls. In cirrhotic rats in vivo, ursodeoxycholate (20 mumoles/min/kg) stimulated bile salt secretion and bile flow less than in controls. Nevertheless, the increment in ursodeoxycholate-induced biliary bicarbonate--the bicarbonate stimulatory potency--was increased by 29% in cirrhotic animals (0.55 +/- 0.08 mmol vs. 0.71 +/- 0.11 mmol; p < 0.05). This finding could be related to ductular proliferation because the volume fraction of bile ductules, determined stereologically, increased from 0.3% +/- 0.1% to 2.7% +/- 0.6% in cirrhotic rats (p < 0.005). To explore further the behavior of ductules during ursodeoxycholate stimulation, we carried out experiments in the in situ perfused rat liver. In the portally perfused organ, replacement of bicarbonate by tricine-acetate abolished ursodeoxycholate-induced hypercholeresis. In the dually perfused organ (perfusion of both portal vein and hepatic artery) perfusion of the hepatic artery with bicarbonate-containing buffer, ursodeoxycholate had a similar stimulatory effect as in vivo in both control and cirrhotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatocellular Na+/H+ exchange is activated at transcriptional and posttranscriptional levels in rat biliary cirrhosis

BACKGROUND/AIMS

Rat hepatocyte Na+/H+ exchange is activated in vitro by growth factors and in vivo following partial hepatectomy. This study explored by which mechanism(s) it is activated in a cirrhosis model characterized by chronic stimulation of hepatocyte proliferation.

METHODS

Rat hepatocytes were isolated 4 weeks after bile duct ligation or sham operation. Intracellular pH (pHi) was fluorimetrically determined, and plasma membranes and messenger RNA (mRNA) were prepared from isolated hepatocytes by standard methods.

RESULTS

Resting pHi was higher in bile duct-ligated than in control rats (7.42 +/- 0.03 vs. 7.06 +/- 0.04; P < 0.001). Although plasma membrane lipid composition and intracellular buffering capacity were similar, initial Na+/H+ exchange-mediated rates of pHi recovery following acid loading were higher in bile duct-ligated than in control rats (0.098 +/- 0.011 vs. 0.055 +/- 0.005 pH units/min; P < 0.05). The antiporter's set point was shifted approximately 0.3 pH units towards more alkaline values and its steady-state mRNA levels were doubled after bile duct ligation.

CONCLUSIONS

Hepatocellular Na+/H+ exchange is transcriptionally and posttranscriptionally activated in rat biliary cirrhosis further supporting a relationship between hepatocyte proliferation and Na+/H+ exchange activation.

[The prevention of Pneumocystis carinii pneumonia by pentamidine inhalation]

167 HIV-positive patients (155 men, 12 women; mean age 31 [18-61] years) with CD4 lymphocyte counts below 250/microliter every 4 weeks received 300 mg pentamidine per aerosol inhalation during out-patient visits, as prophylaxis against Pneumocystis carinii. 89 patients were clinically in the AIDS stage and 33 in the AIDS-related complex (ARC) stage. 29 patients had a lymphadenopathy syndrome, while 16 were asymptomatic. 130 patients received primary prophylaxis, while 37 who had previously had an attack of Pneumocystis carinii pneumonia were given pentamidine as secondary prophylaxis. During a mean observation period of 8 months three patients developed Pneumocystis carinii pneumonia (1.7%): their CD4 lymphocyte count was under 20/microliters. Pentamidine inhalation reduced the incidence of a first attack of pneumonia to 0.18% per month and recurrence to 0.32% per month. These figures confirm the great effectiveness of primary and secondary prophylaxis with pentamidine inhalation.

Improvement of motor performance of HIV-positive patients under AZT therapy

We performed motor tests (most rapid alternating movements [MRAMs] of index fingers and most rapid contractions [MRCs] of voluntary isometric index finger extensions) in HIV-positive patients with (group 1) and without (group 2) AZT treatment over a 6-month period. Whereas MRAMs remained uninfluenced, MRCs showed a clear improvement in the treated group and a decline in the nontreated group, according to the T helper cell counts. MRCs were not only a sensitive test procedure for detecting subclinical lesions in HIV-positive patients, but also a reliable therapy control measurement.

Two cases of cerebral toxoplasmosis in AIDS patients mimicking HIV-related dementia

Two unusual cases of cerebral toxoplasmosis in AIDS patients are presented. Two homosexual males aged 33 and 52 years in CDC stage IV C1 complained of memory loss during the past 6 months, as well as weight loss and mild fever. They showed severe intellectual deterioration and discrete basal ganglia dysfunction. Motor performance and cognitive function as well as the conventional EEG findings were grossly abnormal. MRI was normal in the younger patient but showed signal-intensive zones in the basal ganglia and cortical atrophy in the older one. CSF and serological antibody tests were normal; immunological function was severely impaired. The patients were diagnosed as late "HIV-related dementia". Both deteriorated rapidly and died within a few weeks. Neuropathological examination revealed histologically severe Toxoplasma gondii encephalitis, involving the basal ganglia in particular. It is concluded that in AIDS patients with a severely impaired immune status cerebral opportunistic infection may present as dementia with mild basal ganglia impairment in the absence of other focal neurological signs or the characteristic radiological findings.

[Sex behavior and knowledge about AIDS among students]

604 out of 700 students (330 females, 274 males; mean age 23.3 [19-64] years) completed a questionnaire, which was handed out by their teachers and consisted of 26 questions concerning sexual practices and knowledge about AIDS. 285 subjects were studying natural sciences, 134 arts and 185 medicine. There were significant differences between the sexes (P less than 0.01) in drug use (alcohol, cannabis), use of condoms, promiscuity and with respect to discussion of AIDS. Fewer females than males said that they occasionally used intoxicants before sex (14% vs 25%). Women also used condoms less frequently than men (23% vs 44%), although more insisted on their use if their partner declined (68% vs 58%). 55% of the men and 72% of the women were living within a stable relationship. More women (70%) than men (56%) said they would discuss AIDS before having sex with a new partner. There were significant differences between students from individual disciplines (P less than 0.01) with regard to their knowledge, use of condoms, promiscuity, and discussion of AIDS: arts students were less well informed and changed sexual partners more frequently. The same was true of students more than 30 years old. There are important differences between students with regard to their knowledge about AIDS and sexual behaviour risk factors. Educational programmes need to take this fact into account.

Motor dysfunction in HIV-infected patients without clinically detectable central-nervous deficit

Motor tests were performed in 50 HIV-infected patients in all stages according to the current CDC classification, but without any clinically evident central nervous system deficit, and the results compared with an age-matched control group. Patients were excluded from the study if there was alcohol or drug abuse, fever and/or opportunistic cerebral infection. The parameters tested were postural tremor of the outstretched hands, most rapid voluntary alternating index finger movements (MRAM) and rise time of most rapid index finger extensions (MRC). Whereas tremor peak frequencies did not differ significantly in the patients and controls, MRAM and rise times of MRCs showed significant slowing in the patient group. Morphologically, the motor test performance of the HIV-infected patients was similar to that of patients with manifest basal ganglia disease (Parkinson's, Huntington's and Wilson's diseases). MRI scans of all patients were normal. It is concluded that in HIV-infected patients there is a very early subclinical central nervous system affection, especially of the basal ganglia, which is detectable with appropriate, quantitative motor function tests. These functional abnormalities precede the structural alterations in the MRI scans.

[Changes in the clinical symptomatology of initial manifestations of aids]

We analysed the clinical spectrum of AIDS manifestations of HIV positive patients treated between 1985 and 1988 at the University Hospital of Düsseldorf, West-Germany. In 1985 32 patients with HIV infection (16 asymptomatic, eleven PGL/ARC, five AIDS), 1986 49 patients (17 asymptomatic, 19 PGL/ARC, 13 AIDS), 1987 104 patients (13 asymptomatic, 54 PGL/ARC, 37 AIDS) and 1988 206 patients (23 asymptomatic, 111 PGL/ARC, 72 AIDS) were treated on a in- and out-patient basis. In 1985 five, in 1986 13, in 1987 36 and in 1988 48 patients developed AIDS. Kaposi-sarcoma was seen in 1985 in 40%, in 1986 in 31%, in 1987 in 12% and in 1988 in 9% of these cases. At the same time the rate of patients with opportunistic infections as the primary manifestation of AIDS grew from 60% (1985), 69% (1986), 88% (1987) to 91% (1988). Concomitantly the rate of homosexual patients dropped from 90% (1985), 82% (1986), 60% (1987) to 62% (1988). The rate of i.v. drug abuser rose from 10% (1985) to 24% (1988). In 1985 10% of HIV patients were female. This rate rose up to 18% in 1988. 1987 and 1988 the main opportunistic infections as the primary manifestation of AIDS were pneumocystis carinii pneumonia, toxoplasma encephalitis and candida esophagitis. In summary there is an alteration in the HIV positive population in the last years and concomitantly the clinical spectrum of AIDS is changing.

[Randomized comparative study of secondary prevention of Pneumocystis carinii pneumonia in patients with acquired immunologic deficiency syndrome]

Pneumocystis carinii pneumonia is one of the most frequent infectious complications in patients with the acquired immunodeficiency syndrome (AIDS). A prospective trial was initiated to compare azidothymidine alone with azidothymidine plus aerosolized pentamidine as a secondary prophylaxis for pneumocystis carinii pneumonia. 27 patients (24 male, three female, average age 39 years) were enrolled, 14 patients receiving azidothymidine and pentamidine aerosol and 13 azidothymidine alone. After 166 days of follow-up, this trial had to be terminated prematurely, since the efficacy of pentamidine aerosol in the prevention of pneumocystis carinii pneumonia was clearly demonstrated in two recently published studies. Two patients died during the study period, one in either group, but neither due to pneumocystis carinii pneumonia. Two patients developed histologically proven pneumocystis carinii pneumonia; both patients were allocated to the azidothymidine arm. Pneumocystis carinii pneumonia was suspected clinically but not proven in four patients, three were randomized in the azidothymidine arm. Pentamidine was well tolerated and produced no severe side effects. The sample size is too small to draw definitive conclusions concerning the efficacy of pentamidine aerosol in AIDS patients.