Lack of awareness in both patients and physicians contributes to a high rate of late presentation in a South West German HIV patient cohort.

PURPOSE: To assess rate of late presentation with HIV in Southwestern Germany and to identify patient characteristics correlated with CD4 nadir. METHODS: Patients with primary diagnosis who presented to one of ten participating clinics rated on knowledge and behavior towards HIV testing on a self-developed questionnaire, whereas clinical data was assessed by the physician. RESULTS: 161 patients were included. Risk factors were homosexual (59.5 %) or heterosexual contacts (26.8 %), drug use (2.0 %), migration (3.9 %), or others (7.8 %). 63.5 % had a CD4 T cell count < 350/µl. 52.5, 17.4, and 31.1 % were diagnosed in CDC stadium A, B or C, respectively. 209 disease episodes were reported, from whom 83.7 % had led to the diagnosis of HIV. 75.2 and 68.3 % said to have been well-informed about ways of transmission and testing offerings, respectively, and 20.4 % admitted to have psychologically repressed the possibility of being infected. 48 patients rated their personal behavioral risk as "high" or "very high". Of these, however, only ten had performed at test in the precedent year. Performing a regression analysis, younger age and previous testing were correlated with a higher CD4 T cell nadir (p = 0.005, and 0.018, resp.). CONCLUSION: The rate of late presentation in this region was even higher compared to national or European surveys. Most infected patients perceived to have had only a low risk. Several disease episodes did not lead to the initiation of HIV testing by the physician.

Hepatitis B virus-specific T-cell responses during IFN administration in a small cohort of chronic hepatitis B patients under nucleos(t)ide analogue treatment.

The effect of pegylated interferon-α (IFN) add-on therapy on HBV-specific T-cell responses was evaluated in 12 patients with stable, undetectable hepatitis B virus (HBV) load under nucleos(t)ide analogue therapy. Peripheral blood mononuclear cells were isolated at week 0, 4, 8, 12, 24 and 48 of IFN add-on therapy. Quantity and quality of circulating HBV S- and core-specific CD4 and CD8 T cells were analysed ex vivo by flow cytometry. HBV S- and core-specific CD4 T-cell numbers modestly increased within 8 weeks of IFN administration (P = 0.0391 and P = 0.0195), whereas HBV-specific CD8 T cells in general showed only minor changes under IFN add-on therapy. Functionality of HBV-specific CD4 but not CD8 T cells positively correlated with serum transaminase activity. In addition, we observed an increase in CD4 T cells producing tumour necrosis factor-α (TNFα) without antigen restimulation (P = 0.0039), which correlated with elevated transaminases. During IFN add-on therapy, two patients developed an anti-HBs seroconversion, only one of whom showed a relevant increase in HBV-specific T cells. In conclusion, IFN add-on therapy of chronic hepatitis B increased HBV-specific T-cell responses and affected a previously unrecognized TNFα-monofunctional CD4 T-cell population. Although the observed T-cell responses did not correlate with HBsAg seroconversion, we expect additional insights into the immunopathogenesis of hepatitis B, following the characterization of the newly identified TNF α-monofunctional T-cell population.

Successful treatment of Erdheim-Chester disease with combination of interleukin-1-targeting drugs and high-dose glucocorticoids.

Erdheim-Chester disease (ECD) is a rare histocytic disorder. We report a case of a 45-year-old male ECD patient with severe clinical manifestation (urinary obstruction due to retroperitoneal mass with hydronephrosis, involvement of long bones) and central nervous system involvement (hemiparesis, aphasia and diabetes insipidus). Diagnosis was confirmed by typical clinical, radiological and histological findings. Under immunosuppressive therapy with prednisolone and interleukin-1A receptor antagonist (Anakinra, Kineret, Swedish Orphan Biovitrum AB, Stockholm, Sweden), a rapid improvement of the patients' symptoms and condition was observed. This is the first report of a successful combination therapy of Anakinra and glucocorticoids. Furthermore, current literature about ECD and treatment options are discussed.

[Drug-induced liver injury with an autoimmune phenotype following anti-TNF Therapy - presentation of cases and review of literature]. / Medikamentöse Schädigung der Leber mit autoimmunem Phänotyp durch TNF-Blockade - Fallvorstellung und Review der Literatur.

Therapeutic agents to inhibit tumour necrosis factor alpha (TNF-α) have dramatically improved the treatment options for patients with autoimmune diseases. Common side effects include an increased susceptibility towards infection. Hepatic side effects are less frequently observed. Elevated liver function tests, hyperbilirubinaemia reactivation of chronic viral hepatitis or even acute liver failure have been described. Some cases have exhibited an autoimmune phenotype with the emergence of autoantibodies and characteristic histological lesions. We report on three patients who received anti-TNF therapy for psoriasis and presented with elevated liver function tests in the further course. Histological and serum analysis revealed an autoimmune phenotype of liver injury. In light of the growing use of anti-TNF therapies, drug-induced liver injury (DILI) with an autoimmune phenotype is an important side effect. Since the pathophysiological mechanisms related to the autoimmune phenotype of liver injury during TNF-inhibition are not well understood, the cases detailed herein should help treating physicians to improve their understanding of the situation.

Disclosure behaviour and experienced reactions in patients with HIV versus chronic viral hepatitis or diabetes mellitus in Germany.

Disclosure is a prerequisite to receive disease-specific social support. However, in the case of a stigmatised disease, it can also lead to discrimination. We aimed to assess disclosure rates of HIV patients and the reactions they encountered in comparison to patients with chronic viral hepatitis or diabetes mellitus and patients' general perception of disease-specific discrimination. We constructed a self-report questionnaire, anonymously assessing the size of the social environment, the persons who had been informed, and the experienced reactions as perceived by the disclosing patients, to be rated on 1-4 point Likert scales. In addition, patients were asked whether they perceive general discrimination in Germany. One hundred and seventy-one patients were asked to participate. Five rejected, thus questionnaires from 83 patients with HIV, 42 patients with chronic viral hepatitis B (n = 9) or C (n = 33), and 41 patients with insulin-dependent diabetes mellitus (type I n = 14, type II n = 27) were analysed. Whereas the size of the social environment did not differ, HIV-infected patients were least likely to disclose their disease (60.7%, SD ± 31.9) to their social environment as compared to patients with chronic viral hepatitis (84.2 ± 23.3%, p<0.0001), or diabetes mellitus (94.4 ± 10.3%, p<0.0001), respectively. Within the HIV patient group, the mean disclosure rate was highest to partners (90.9%), followed by the public environment (65.2%), friends (59.4%) and family members (43.8%). HIV patients experienced supportive reactions after 79.3 ± 26.4% of disclosures, which was the case in 91.4 ± 19.6% and 75.7 ± 36.1% of patients with hepatitis or diabetes mellitus, respectively. 69.5% of HIV patients stated to perceive general discrimination in Germany. We conclude that HIV patients had experienced supportive reactions after the majority of disclosures, but the low rate points out that their information strategy had been very selective. Societal discrimination of HIV patients is still an issue and needs to be further addressed.

[With the scalpel against the immune system: HIV infection complicated by an unclear colitis]. / Mit dem Skalpell gegen das Immunsystem: eine unklare Kolitis bei HIV-Infektion.

A 35-year-old Kenian lady with advanced immunodeficiency due to HIV infection started on an antiretroviral therapy. Five months later, a severe colitis was diagnosed, however, no causal pathogen could be found. In order to avoid imminent perforation, a hemicolectomy became necessary, and immediately the symptoms and inflammation markers normalized rapidly. M. tuberculosis could be proven in culture in a draining abdominal lymph node. We assume that the severe inflammation was caused by an immune restoration inflammatory syndrome (IRIS). Essentials in diagnosis, pathogenesis and therapy of IRIS are discussed.

IgG4-related sclerosing cholangitis mimicking cholangiocarcinoma.

IgG4-related disease has gained increased attention worldwide. While the initial focus was on autoimmune pancreatitis which was first described in Asian populations and turned out to be of relevance in Western populations too, the scope has recently broadened towards a notion of a multi-systemic disease with very diverse manifestations such as autoimmune pancreatitis, IgG4-related sclerosing cholangitis (IgG4-SC), retroperitoneal fibrosis and tubulointerstitial nephritis. IgG4-SC (also known as IgG4-associated cholangitis, IAC) represents a rare but clinically challenging differential diagnosis in patients with obstructive jaundice and proximal extra- or intrahepatic biliary strictures which can be mistaken for cholangiocarcinoma (CC). We present the case of a 79-year-old male patient who presented with obstructive jaundice and biliary strictures at the hepatic duct bifurcation without any evidence for autoimmune pancreatitis and without elevation of serum IgG4-concentrations who underwent hemihepatectomy for suspected CC. However, on histological examination of the resection specimen CC could not be confirmed. It was only after several episodes of obstructive jaundice had reoccurred that the diagnosis of IgG4-SC could be established by reexamination of the surgical specimen which showed extensive infiltration with IgG4-positive plasma cells. Appropriate medical treatment with steroids and azathioprine led to complete remission of the disease. Early recognition of IgG4-SC can save patients from potential harmful and unnecessary surgical interventions. Here we describe the clinical features of this rare case of IgG4-SC with extensive liver tissue infiltration with IgG4-positive cells but without elevated serum IgG4 concentration or evidence of autoimmune pancreatitis. We describe diagnostic criteria for IgG4-SC and review recent insights in pathophysiology and treatment options.

Klatskin tumour: meticulous preoperative work-up and resection rate.

BACKGROUND: Surgery represents the only potentially curative treatment of hilar cholangiocarcinoma (hilCC). It may be suggested that meticulous preoperative work-up in Asian countries leads to higher resection rates. METHOD: One hundred and eighty-two patients treated in our department between 1998 and 2008 were included in an analysis based on our prospectively recorded database. Among them, 75 % had a percutaneous transhepatic cholangiography as part of their diagnostic work-up. A total of 160 patients underwent explorative surgery and 123 patients were resected (77 % of patients undergoing exploration, 68 % of all patients). RESULTS: Ninety-one percent of the patients were diagnosed to have Bismuth III and IV tumours. En-bloc resection of the tumour and the adjacent liver including segment 1 was the standard procedure in 109 of these patients, while hilar resection was performed in 14 patients. Upon tumour resection, hospital mortality was 5.7 %. Five-year survival in patients without surgery or with mere exploration was 0 %, after resection it reached 26 %. Patients with R 1 resection experienced longer survival than patients without resection (p < 0.001). Right and left hemihepatectomies were performed with identical frequency resulting in identical survival. Lymph node involvement proved to be the only significant predictor of prognosis (p = 0.006). CONCLUSION: Resection should be performed whenever possible since even after palliative resection survival is substantially increased compared to patients without resection. Meticulous preoperative work-up may contribute to a high resection rate in patients with hilCC by providing additional information allowing the surgeon to perform more aggressive approaches.

Acute renal failure and liver dysfunction after subcutaneous injection of 3-sn-phosphatidylcholine (Lipostabil®)-case report.

INTRODUCTION: Drug-induced tubulointerstitial nephritis and acute tubular necrosis are common, and are often caused by drugs especially antibiotics or non-steroidal anti-inflammatory drugs. Drug-induced liver dysfunction and renal failure after subcutaneous injection of phosphatidylcholine was not reported so far. 3-sn-Phosphatidylcholine has been described as a cell lysis reaction-inducing drug. Its in vitro data indicated a relevant toxicity potential. In particular human cell types such as fibroblast-like preadipocytes, vascular and skeletal muscle cells, or renal epithelial cells react more sensitive than other human cell types. CASE REPORT: We present a 28-year-old woman who received 3.5 g (70 mL) of 3-sn-phosphatidylcholine (Lipostabil®) at once subcutaneously (s. c.) in both gluteal regions. The drug was originally introduced to prevent fat embolism. Nevertheless, its off-label use in aesthetic therapy for treatment of localized fat deposits through subcutaneous administration is becoming increasingly common. Three hours after injection the patient suffered from severe nausea and emesis. Within 24 hours a dramatic increase of liver enzymes and a beginning liver dysfunction were observed. Subsequently, renal function deteriorated two days later making a temporary haemodialysis necessary. Hepatic improvement was observed after three days of treatment. Renal function was fully recovered after two weeks. CONCLUSION: To the best of our knowledge, this is the first reported patient presenting with acute liver dysfunction and renal failure after subcutaneous injection of 3-sn-phosphatidyl-choline (Lipostabil®) indicating the risk of an off-label use of this drug.

The programmed death (PD)-1/PD-ligand 1 pathway regulates graft-versus-host-reactive CD8 T cells after liver transplantation.

Acute graft-versus-host disease (aGVHD) is a life-threatening complication after solid-organ transplantation, which is mediated by host-reactive donor T cells emigrating from the allograft. We report on two liver transplant recipients who developed an almost complete donor chimerism in peripheral blood and bone marrow-infiltrating T cells during aGVHD. By analyzing these T cells directly ex vivo, we found that they died by apoptosis over time without evidence of rejection by host T cells. The host-versus-donor reactivity was selectively impaired, as anti-third-party and antiviral T cells were still detectable in the host repertoire. These findings support the acquired donor-specific allotolerance concept previously established in animal transplantation studies. We also observed that the resolution of aGVHD was not accompanied by an expansion of circulating immunosuppressive CD4/CD25/FoxP3-positive T cells. In fact, graft-versus-host-reactive T cells were controlled by an alternative negative regulatory pathway, executed by the programmed death (PD)-1 receptor and its ligand PD-L1. We found high PD-1 expression on donor CD4 and CD8 T cells. In addition, blocking PD-L1 on host-derived cells significantly enhanced alloreactivity by CD8 T cells in vitro. We suggest the interference with the PD-1/PD-L1 pathway as a therapeutic strategy to control graft-versus-host-reactive T cells in allograft recipients.

[Single center experience over a 5-year period with sequential transarterial chemoembolization (TACE) in the treatment of hepatocellular carcinoma (HCC)]. / Sequentielle transarterielle Chemoembolisation (TACE) des hepatozellulären Karzinoms (HCC)--Erfahrungsbericht eines einzelnen Zentrums über 5 Jahre.

PURPOSE: To analyze the course of disease of patients treated with sequential TACE and to evaluate the dependent and independent prognostic factors for patient survival using the Cox Proportional Hazard Model. MATERIALS AND METHODS: 94 patients palliatively treated with TACE. Patients were selected if they had been treated at least 3 times. The TACE procedure was carried out at 8-week intervals using a suspension consisting of a fixed dosage of Mitomycin C (10 mg) and 10 ml Lipiodol. Follow-up investigations included contrast-enhanced multislice CT before and after TACE and assessment of the laboratory test results (i. e., blood count, liver enzymes, and coagulation). RESULTS: In 66.7 % of the patients, multifocal tumors were found. In 16.0 % of the patients, the tumor load represented more then 50 % of the liver volume. In 23.4 % of the cases, a portal vein thrombosis was found in the initial CT scan. The mean survival for the total cohort was 24.1 months (95 %-CI 20.1 - 28.2). During the investigation period, 72/94 of the patients died. The cumulative 1-year, 2-year, and 3-year survival rates are 71.6 %, 33.9 %, und 17.2 %, respectively. A median of 6.0 +/- 3.1 (range 14, n total = 612 TACE) was performed in each patient. A total of 62.5 % patients died because of tumor progression whereas 18.1 % died due to progressive liver failure. Patients in whom the tumor responded to the TACE treatment and who did not develop ascites or those with Okuda stage I or unifocal tumor growth showed a survival benefit whereas the presence of portal vein thrombosis was associated with a significantly poor outcome (p < 0.05). The Child-Pugh stage was not statistically significant for the disease course; the occurrence of new tumor lesions had no influence with regard to 1-year and 2-year survival but had a significant influence on long-term survival (p < 0.05). Independent prognostic factors are (multivariate analysis; p < 0.05): number of TACE performed, tumor type (i. e., unifocal vs. multifocal), response to TACE (response vs. progression), and Okuda stage. CONCLUSION: Our results emphasize the value of TACE in the palliative treatment of HCC. Under sequential TACE therapy the course of disease in patients suffering from portal vein thrombosis was not significantly worse. Crucial prognostic factors for the course of the HCC are tumor type and extension, response to TACE, and liver function at the beginning of TACE.

Transarterial chemoembolization before liver transplantation in 60 patients with hepatocellular carcinoma.

Tumor recurrence is a major problem after orthotopic liver transplantation (OLT) in patients with hepatocellular carcinoma (HCC). In 60 patients OLT was performed for HCC after pretreatment by repeated transarterial chemoembolization (TACE). Forty-four recipients exceeded the Milan criteria. Recurrence-free 5-year survival was 65.2% and 5-year freedom from recurrence was 73.2%. During the waiting time, 14 patients experienced minimal change, which did not fulfill the definition of tumor progression according to official oncological criteria. Five-year freedom from recurrence among patients with stable compared with progressive disease was 93.3% versus 28.1%, respectively (P = .0001). A strict TACE pretreatment protocol may select patients with obviously biologically less aggressive tumors, who are suitable for OLT even if the HCC exceeds the commonly accepted listing criteria.

Histone deacetylase inhibition by valproic acid down-regulates c-FLIP/CASH and sensitizes hepatoma cells towards CD95- and TRAIL receptor-mediated apoptosis and chemotherapy.

Hepatocellular carcinoma (HCC) is highly resistant to chemotherapy, leading to a poor prognosis of advanced disease. Inhibitors of histone deacetylase (HDACi) induce re-differentiation in tumor cells and thereby re-establish sensitivity towards apoptotic stimuli. HDACi are entering the clinical stage of tumor treatment, and several substances are currently being tested in clinical trials to prove their efficacy in the treatment of leukemias and solid tumors. In this study, we investigated the impact of the HDACi valproic acid (VA) on TRAIL- and CD95-mediated apoptosis in hepatoma cells, as well as its sensitizing effect on a chemotherapeutic agent. Treatment of HepG2 cells with VA increased sensitivity to CD95-mediated apoptosis (4% apoptosis vs. 42%), and treatment with epirubicin (74% vs. 90% viability). Caspase-3 activity was significantly enhanced in cells treated with VA plus anti-CD95 antibodies compared to cells treated with antibodies alone. In parallel, VA strongly augmented the effect of TNF-related apoptosis-inducing ligand (TRAIL or Apo2 ligand) on HepG2 cells (10% vs. 58% apoptosis). VA induced down-regulation of cellular FLICE-inhibitory protein (c-FLIP/CASH, also known as Casper/iFLICE/FLAME-1/CLARP/MRIT/usurpin), providing a possible molecular mechanism underlying the increased sensitivity towards cell death-mediated apoptosis. HDAC inhibitors are a promising class for the treatment of leukemias. In addition, among other class members, VA deserves further evaluation as a treatment option for patients with advanced HCC.

[Discharge medication - what do patients know about their medication on discharge?]. / Entlassungsmedikation - Was weiß der Patient bei Entlassung über seine Arzneimittel?

BACKGROUND: Patients' lack of knowledge about their discharge medication can endanger patients' safety after their hospital stay. This is especially the case with regard to medications that were newly prescribed during the hospital stay and are intended to be used after discharge or medications with an increased risk for adverse drug reactions (high-risk drugs). The aim of this study was to analyse the patients' level of knowledge about their discharge medication and to identify influence factors. METHODS: In a bicentric survey patients were interviewed prior to their discharge from an acute and a geriatric rehabilitation hospital. They were asked about their discharge medication in a structured interview. Influence factors were statistically analysed by Tobit regression. RESULTS: In total, 179 patients were interviewed. On average, patients named 48% of their discharge medication correctly (95% CI: 46-50%). Influence factors for knowledge deficits were the lack of a medication plan, an older age, the hospitalization in a rehabilitation hospital and a long hospitalization. 81% of the patients had at least one drug in their discharge medication, which was newly prescribed during the hospital stay. 11% of those drugs were named correctly, the potency was named correctly in 6%, the indication in 8%. For almost two-thirds of the patients at least one high-risk drug was recommended in the discharge letter, among them most frequently oral anticoagulants and opioid analgesics. 38% of these high-risk drugs were named correctly. CONCLUSION: Our results demonstrate an urgent need to train patients about their discharge medication, especially if medications are included that were newly prescribed during the hospital stay and recommended for further use after discharge or medications with an increased risk of adverse drug reactions. Particularly older patients and patients of a rehabilitation hospital after long hospitalization should be intensively counselled and obtain a medication plan upon discharge.

Acute organ failure following the loss of anti-apoptotic cellular FLICE-inhibitory protein involves activation of innate immune receptors.

Apoptosis signaling is involved in both physiological tissue homeostasis and acute and chronic diseases. The role of regulatory apoptosis signaling molecules and their organ-specific functions are less defined. Therefore, we investigated the loss of the anti-apoptotic cellular FLICE-inhibitory protein (cFLIP) and the mechanisms of the resulting lethal organ failure in vivo using inducible knockout mice. These were generated by crossing floxed cFLIP mice to a tamoxifen inducible Rosa26-creERT2 mouse strain. Death following global loss of cFLIP resulted from liver failure, accumulation of M1-polarized macrophages and accompanying hepatic cell death and inflammation. Apoptosis was also prominent in immune cells, the kidney and intestinal epithelial cells (IECs) but not in cardiomyocytes. Cellular injury led to the release of damage-associated molecular patterns (DAMPs) and the induction of innate immune receptors including toll-like receptors (TLRs) 4 and 9, and stimulator of interferon genes (STING). Transplantation of bone marrow with intact cFLIP or depletion of macrophages prevented the phenotype of acute liver failure. Interestingly, compound deletion of cFLIP in bone marrow-derived cells and hepatocytes did not promote organ failure. Thus, cFLIP exerts a critical role in tissue homeostasis by preventing the activation of monocytic cells and innate immunity, which causes cell death and inflammation in susceptible tissues. These results encourage the development of organ-specific anti-apoptotic and anti-inflammatory therapies in acute organ failure.

Enhancement of radiation-induced base release from nucleosides in alkaline solution: essential role of the O.- radical.

The effect of pH on base release in the gamma-radiolysis of N2O-saturated solutions of a number of nucleosides (including uridine, 3-methyluridine, 2',3'-O-isopropylidene-uridine, and adenosine) has been investigated. For all these nucleotides, independent of the base or sugar moiety, base release is very low at pH below 10 (G approximately (0.3-0.7) x 10(-7) mol J-1), but increases drastically to G approximately (3-4) x 10(-7) mol J-1 at pH greater than or equal to 13. This phenomenon had already been previously reported and attributed to an OH(-)-induced transfer of a base radical into a sugar radical. However, it is now shown that at pH 12, where base release starts to increase, a lowering of the dose-rate does not affect the yield of free base. The increase in base release is accompanied by an overall reduction of chromophore loss of similar magnitude (with 2',3'-O-isopropylidene-uridine and 3-methyluridine), as well as by an increase in the yield of oxidizing radicals by a factor of 2 (with uridine). The measured rate constant of the reaction of .OH/O.- with the nucleosides is also pH-dependent, as .OH reacts faster than O.- with the nucleosides by a factor of 6-7. It is concluded that the increase in base release at high pH is caused by the increasing participation of O.-, which, unlike .OH, attacks the nucleosides preferentially at their sugar moieties, and is not due to an OH(-)-induced radical transfer from the base to the sugar moiety.

Electron transfer from nucleobase electron adducts to 5-bromouracil. Is guanine an ultimate sink for the electron in irradiated DNA?

Electron transfer to 5-bromouracil (5-BrU) from nucleobase (N) electron adducts (and their protonated forms) has been studied by product analysis and pulse radiolysis. When an electron is transferred to 5-BrU, the ensuing 5-BrU radical anion rapidly loses a bromide ion; the uracilyl radical thus formed reacts with added t-butanol, yielding uracil. From the uracil yields measured as the function of [N]/[5-BrU] after gamma-radiolysis of Ar-saturated solutions it is concluded that thymine and adenine electron adducts and their heteroatomprotonated forms transfer electrons quantitatively to 5-BrU. Like the electron adduct of adenine, those of cytosine and guanine are rapidly protonated by water. The (protonated) electron adduct of guanine does not transfer an electron to 5-BrU, and in the case of the (protonated) cytosine electron adduct only partial electron transfer is observed. The results can be modelled if the protonated electron adduct (protonated at N(3) or at the amino group) of cytosine, CH., which can transfer its electron to 5-BrU (k approximately 2 x 10(7) dm3 mol-1 s-1) is transformed in a slow tautomerization reaction (k approximately 2.5 x +/- 10(3) s-1) into another form C'H. (possibly protonated at C(6) or C(5)) which does not transfer an electron to 5-BrU. There is also electron transfer from the electron adduct of thymine to cytosine and guanine which serve as electron sinks. The rate constant of electron transfer from the thymine electron adduct to cytosine is about 250 times greater than that of the reverse reaction. The heteroatom-protonated electron-adduct of thymidine transfers an electron to 5-BrU more slowly (k = 2.3 x 10(7) dm3 mol-1 s-1) than the electron-adduct itself (k = 7.2 x 10(8) dm3 mol-1 s-1). Phosphate buffer-induced protonation of the electron-adduct of thymine at carbon (C(6)) prevents electron transfer to 5-BrU. Such phosphate catalysis is also observed as an intramolecular process (k approximately 2 x 10(4) s-1) with thymidine-5'-phosphate but not with the 3'-phosphate. Phosphate-induced protonation at carbon also reduces transfer efficiency for the electron adducts of dinucleoside phosphates such as dTpdT and dTpdA. The data raise the question whether in DNA the guanine moiety may act as the ultimate sink of the electron in competition with other processes such as protonation at C(6) of the thymine electron adduct.

Reaction of hydroxyl radicals with alkyl phosphates and the oxidation of phosphatoalkyl radicals by nitro compounds.

The rate constants for reactions of hydroxyl radicals with a number of alkyl phosphates have been determined by competition with KSCN. Hydroxyl radicals react with alkyl phosphates preferentially by H-abstraction at the alpha-position of the phosphate functions. The resulting alpha-phosphatoalkyl radicals are not very efficient one-electron reducing agents towards nitro compounds. They react with tetranitromethane (TNM) by addition to form adduct intermediates with absorption maxima at about 300 nm. The rate constants for decay of these TNM adducts to produce the nitroform anion (NF-) and the corresponding alpha-phosphato-alcohols have been determined by optical and/or conductance detection. The stability of these TNM adducts varies considerably with the chain length (methyl > ethyl > isopropyl) and number (trialkyl > dialkyl > monoalkyl) of the alkyl substituents. Additional formation of proton during or after the decay of the TNM adducts has been tentatively attributed to the hydrolysis of the alpha-phosphato-alcohols. Alpha-Phosphatoalkyl radicals derived from trimethyl, triethyl, triisopropyl, and diethyl phosphates react with p-nitroacetophenone (PNAP) very slowly (k < 5 x 10(7) dm3mol-1S-1) possibly forming adducts. One-electron reduction of PNAP by these radicals to PNAP.- was not observed under pulse radiolysis conditions. The rate constants for the reactions of .OH with glycerol 1-phosphate and glycerol 2-phosphate have been redetermined by competition with KSCN. Using the radical scavengers N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) and TNM, the percentage of .OH attack at each carbon atom was obtained. Contrary to the simple alkyl phosphates described above, the alpha-position to the phosphate function is the least favoured (10-15% in glycerol 1-phosphate and 6% in glycerol 2-phosphate). These so-formed alpha-phosphatoalkyl radicals react with TNM also by forming adducts. The beta-phosphatoalkyl radicals in both cases eliminate inorganic phosphate on formation (k > 10(6)S-1). The gamma-phosphatoalkyl radical from glycerol 1-phosphate undergoes base-catalysed water elimination (kobs = 1.8 x 10(5)S-1 at pH 10.6) to give an oxidizing radical. Products in the gamma-radiolysis of N2O-saturated solutions of glycerol 1-phosphate and glycerol 2-phosphate have been identified and their yields determined. The mechanisms for their formation are discussed.

Addition of e-aq and H atoms to hypoxanthine and inosine and the reactions of alpha-hydroxyalkyl radicals with purines. A pulse radiolysis and product analysis study.

The reactions of hydrated electrons e-aq with hypoxanthine and inosine were followed using pulse radiolysis methods. In a neutral solution the electron adduct of inosine is immediately protonated at the heteroatoms of the purine ring by water (k >> 2.5 x 10(6)s-1) to give In(N,O-H).. These N,O-protonated intermediates have a single absorption maximum at 300 nm. In basic solution the protonation of the electron adduct of inosine by water leads to other intermediate products with an absorption maximum at 350 nm. These intermediates are believed to be the C-protonated electron adducts of inosine (In(N,O-H).). In (N,O-H). and In(C-H). differ strongly in their ability to reduce p-nitroacetophenone (PNAP). In(N,O-H). are strong reductants and reduce PNAP quantitatively to PNAP.-. Based on the pH dependence of PNAP.- yields, two types of tautomers of In(C-H). could be distinguished. One of the tautomers can reduce PNAP, albeit with slower rate than In(N,O-H)., the other tautomer has no reducing properties. The latter is the one with the higher pKa and therefore thermodynamically more stable. The absorption spectrum of the intermediates produced in the reaction of e-aq with hypoxanthine at neutral pH is very similar to that of In(N,O-H). with a maximum at 300 nm. However, no build-up at 350 nm was observed in basic solution as in the case of the electron adduct of inosine. The reaction of H atoms with inosine produces in basic solution intermediate radicals with the same absorption spectrum as the C-protonated electron adducts of inosine. It is suggested that both the reactions of e-aq and H. with inosine in basic solution produce the same radical, namely the H-adduct of inosine (In(C-H)) with the highest pKa. alpha-Hydroxyalkyl radicals were found to react very slowly with purine bases and nucleosides in neutral to basic solutions. In acidic solution their reactivity increases and a number of rate constants were determined by pulse radiolysis measurements at pH 0.4. The intermediates from the reaction of 2-hydroxy-2-propyl radicals with inosine could be observed pulse spectrometrically in neutral and in basic solutions. In basic solution this reaction leads to intermediates with the same absorption maximum at 350 nm as that of the H-adduct of inosine. Furthermore, the yield of acetone was found to increase strongly in basic pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Apoptosis in liver disease.

A variety of biological functions are regulated through extracellular signals. Amongst the best studied examples is growth control, which is achieved by the regulatory function of growth factors. In recent years it has become apparent that cell death (apoptosis) is controlled in a similar fashion.Apoptosis, firstly a morphologically defined process, is a highly controlled type of cell death that plays a critical role in embryonic development, deletion of autoreactive T-cells and adult tissue homoeostasis. There is increasing evidence that derangement of the apoptotic program is the underlying cause of a series of diseases including liver diseases. The deadly program can be initiated by ligand binding to membrane bound receptors such as CD95 (Fas), which is the most prominent cell death inducing member of the TNF receptor superfamily. The core of the subsequently activated intracellular machinery is formed by a set of proteases, namely caspases. Once activated, they orchestrate the complete destruction of the cellular skeleton leading to the typical apoptotic morphology. This review focuses on the underlying mechanism leading to derangement of the usually highly controlled apoptotic program in different liver diseases.