Hepatitis B and circadian rhythm of the liver

The circadian rhythm in humans is determined by the central clock located in the hypothalamus’s suprachiasmatic nucleus, and it synchronizes the peripheral clocks in other tissues. Circadian clock genes and clock-controlled genes exist in almost all cell types. They have an essential role in many physiological processes, including lipid metabolism in the liver, regulation of the immune system, and the severity of infections. In addition, circadian rhythm genes can stimulate the immune response of host cells to virus infection. Hepatitis B virus (HBV) infection is the leading cause of liver disease and liver cancer globally. HBV infection depends on the host cell, and hepatocyte circadian rhythm genes are associated with HBV replication, survival, and spread. The core circadian rhythm proteins, REV-ERB and brain and muscle ARNTL-like protein 1, have a crucial role in HBV replication in hepatocytes. In addition to influencing the virus’s life cycle, the circadian rhythm also affects the pharmacokinetics and efficacy of antiviral vaccines. Therefore, it is vital to apply antiviral therapy at the appropriate time of day to reduce toxicity and improve the effectiveness of antiviral treatment. For these reasons, understanding the role of the circadian rhythm in the regulation of HBV infection and host responses to the virus provides us with a new perspective of the interplay of the circadian rhythm and anti-HBV therapy. Therefore, this review emphasizes the importance of the circadian rhythm in HBV infection and the optimization of antiviral treatment based on the circadian rhythm-dependent immune response.     

Inhibition of induction of natural killer activity in mice by general anesthesia (Avertin): role of interferon.

We have previously reported that general anesthesia (Avertin) inhibits the induction of natural killer (NK) cell activity following administration of Poly I:C in vivo. Since Poly I:C has been shown to increase NK activity through the induction of interferon (IFN), the current study examines the role of IFN in this inhibition. The data suggest that (i) anesthesia does not affect the ability of Poly I:C to induce endogenous IFN synthesis (serum IFN levels are unaltered by anesthesia) and (ii) anesthesia is capable of inhibiting stimulation of NK activity induced directly by treatment with IFN either in vivo or in vitro. The duration of the former effect was at least 10 days, with complete recovery by Day 14 after anesthesia. Interestingly, NK activity stimulated by IFN prior to anesthesia was not significantly altered. In view of the increasingly evident role of NK cells in anti-tumor and anti-infectious host defenses, their inertness to stimulation in the post-anesthesia period may be a significant contributing factor to the clinically observed postoperative morbidity. Thus, preanesthesia stimulation of NK activity with IFN may be of therapeutic value.     

Chronic peritoneal dialysis in paediatrics: Experience of a national registry

The results of the first 3 year' collaboration of the Italian Registry of Paediatric Chronic Peritoneal Dialysis (CPD) (1986–1988) are presented. This Registry acquired data on the majority of the paediatric patients treated with CPD in Italy, thus providing a national picture in a field where few nationwide surveys are available. Patients of less than 15 years of age at the start of dialysis were enrolled and clinical data collected until the age of 19 years. The number of nephrological paediatric centres participating in the Registry increased from 7 in 1986 to 11 in 1988. The total number of patients on CPD was 70 and the percentage of dialysed children treated with CPD ranged from 40.2% to 43.6%. Data on 89 peritoneal catheters were collected: during 1417 dialysis-months 70 catheter-related complications were observed (1:20.8 dialysis-months); actuarial catheter survival was 92.7% at 6 months, 84.8% at 1 year and 68.8% at 2 years. The incidence of peritonitis changed from 1 episode every 10.9 patient-months in 1986 to 1 every 19.8 in 1988. Abdominal hernias were the other main clinical complication observed. The survival of patients was 92.5% at 3 years, while the technique survival at the same time was 84%.     

Bradykinin-induced release of thromboxane B2 into bronchoalveolar lavage fluid of guinea pigs: relationship to airflow obstruction

The aim of this study was to evaluate the role of thromboxane A₂ in bradykinin-induced airflow obstruction in guinea pig in vivo. Airway insufflation pressure (P_i) was measured to assess airflow obstruction and the thromboxane B₂ (a stable metabolite of thromboxane A₂) concentration in bronchoalvelolar lavage fluid was determined by radioimmunoassay. The animals were pretreated with propranolol (1 mg/kg i.v.) and suxamethonium (5 mg i.v.) prior to bradykinin administration. Bradykinin instillation into the trachea (300 nmol) induced a P_i increase (47.5 ± 8.3 cm H₂O versus 23.8 ± 1.5 in sham) and significant thromboxane B₂ release into bronchoalveolar lavage fluid (79 ± 19 pg/ml versus 19 ± 6 in sham). A thromboxane synthase inhibitor (OKY-046, 30 mg/kg i.v.; ((E-E)-3-[p(1H-imidazole-1-yl-methyl) phenyl]-2-propenoic acid hydrochloride mono-hydrate)) or a thromboxane A₂ receptor antagonist (ICI192,605, 0.5 mg/kg i.v.; (4-(Z)-6-(2-o-chloro-phenyl-4-o-hydroxyphenyl-1,3-dioxan-cis-5-yl)hexenoic acid)) reduced the P_i increase evoked by bradykinin (38.7 ± 3.8 and 40.6 ± 3.8 cm H₂O, respectively). OKY-046 abolished the thromboxane B₂ release. A platelet-activating factor receptor antagonist, WEB2086 (1 mg/kg i.v.; (3-[4-(chlorophenyl)-9-methyl-6H-thienol [3,2-f][1,2,4]trizolo-[4,3-a][1,4] diazepin-2-yl]1-4-(4-morpholinyl)-1-propanon) did not significantly affect any measured parameter. We conclude that, in guinea pigs, bradykinin-induced airway effects are associated with a local thromboxane A₂ release.     

Increased in vivo frequency of IA-2 peptide-reactive IFNgamma+/IL-4- T cells in type 1 diabetic subjects

Active T cell recognition of islet antigens has been postulated as the pathogenic mechanism in human type 1 diabetes, but evidence is scarce. If T cells are engaged, they are expected to display increased clonal size and exhibit a T helper (Th)1/Th2 differentiation state. We used a peptide library that covers tyrosine phosphatase IA-2, a target antigen expressed in pancreatic beta cells, to probe 8 diabetic patients and 5 HLA-matched controls. When tested in a high resolution IFNgamma/IL-4 double color ELISPOT assay directly ex vivo, the number of IA-2-reactive IFNgamma producing cells was 17-fold higher in patients than in controls and IL-4 producing cells were not present. An average of 9 peptides was recognized in the patients vs. one in the controls. Determinant recognition primarily involved CD4+ cells and showed high variability among the patients. Furthermore, anti-CD28 antibody signal enhances quantitative assessment of effector T cells in T1D patients. In vitro expansion with peptides and IL-2 results in detection of responding cells in the controls and loss of disease specificity of the T cell response. Together these data provide strong evidence for the active targeting of IA-2 by Th1 memory effector cells in human type 1 diabetes.     

Co-expression of Epstein-Barr virus latent membrane protein and vimentin in “aggressive” histological subtypes of Hodgkin's disease

Summary The presence of Epstein-Barr virus (EBV) genome in Hodgkin's and Reed-Sternberg (HRS) cells, as detected using in situ hybridization (ISH) with biotinylatedBamHI V probes, along with the expression of EBV-encoded latent membrane protein (LMP) and vimentin was examined in paraffin-embedded sections of 39 immunomorphologically characterized cases of Hodgkin's disease (HD). ISH demonstrated EBV in HRS cells in 15 of 39 cases, whereas LMP expression was detected in 11 of 39 cases, only in the presence of EBV genome detection. With the exception of 1 case, in which HRS cells expressed B-cell-associated antigens, the LMP-positive cases included specimens in which HRS cells were of non-B, non-T phenotype. LMP expression showed a stronger association with lymphocyte depletion (LD) (3/3) and mixed cellularity (MC) (6/11) than with lymphocyte predominance (0/5) or nodular sclerosis (2/20) subtypes. Vimentin expression on HRS cells was found in all the LMP-expressing cases and only in a fraction (13/28) of LMP-negative cases. This study supports the view that HD represents a heterogeneous group of diseases also in terms of EBV association, LMP expression being strongly related to the aggressive LD and MC histological subtypes. In light of the supposed interactions between vimentin and LMP, their coexpression on HRS cells, as detected in this study, provides further evidence for a significant role of EBV in the development of a proportion of HD cases.     

Adsorption and dissolution behavior of human plasma fibronectin on thermally and chemically modified titanium dioxide particles.

Titanium is known for its biocompatibility and is widely used in dental and orthopedic reconstructive surgery. There are reports that osteointegration of these implants is not optimal. The objective of this study was to modify titanium dioxide particles and examine the resultant effects on protein adsorption to these altered surfaces using a model cell binding protein, human plasma fibronectin (HPF). HPF is an important matrix glycoprotein that plays a major role in cell and protein attachment, Titanium dioxide surfaces were modified by heating the titanium dioxide powder at 800 degrees C for 1 h or treating with an oxidizing agent: peroxide in ammonium hydroxide followed by peroxide in hydrochloric acid. Oxidized and control samples were further treated with 9:1 butanol:water for 30 min. Brunauer-Emmett-Teller showed no change in particle surface area as a result of thermal or chemical treatment. Hydrophobicity increased with butanol treatment of titanium dioxide. Diffuse reflectance Fourier transform infrared spectroscopy showed the presence of -CH2 and -CH3 vibrations in the region of 2850-3000 cm(-1) for both the heated, butanol and peroxide/butanol-treated samples. The absence of increased C-O and O-C=O features as determined by electron spectroscopy for chemical analysis indicates that butanol adsorption is not occurring via an esterification mechanism. The interaction between butanol and pre-heated or peroxide-treated titanium dioxide may be one of association (weak electrostatic and/or Van der Waals forces) rather than direct ionic bonding. Maximum HPF adsorption on modified or unmodified titanium dioxide occurred within 30 min, with greater protein adsorption occurring on butanol-treated samples. Desorption was minimal with all modifications. Zeta potential measurements showed that HPF adsorption caused an increase in the negative zeta potential with the greatest change noted for the butanol-treated samples. These findings suggest that wettability and surface charge both play an important role in protein adsorption to titanium dioxide. Thus, by modifying the physico-chemical properties of titanium dioxide surfaces, it may be possible to alter protein adsorption and hence optimize cell attachment.     

Identification and characterization of clinical isolates of members of the Staphylococcus sciuri group

A total of 28 staphylococcal isolates from human clinical specimens belonging to the Staphylococcus sciuri group were identified and characterized. The API Staph and ID32 STAPH correctly identified S. sciuri and S. lentus but not S. vitulinus strains. Identification to the subspecies level was possible only by a PCR-based method.     

T Cells Recognize Multiple GAD65 and Proinsulin Epitopes in Human Type 1 Diabetes, Suggesting Determinant Spreading

Human type 1 diabetes is thought to be mediated by autoreactive T cells specific for antigens expressed by pancreatic beta cells. However, it is unclear which autoantigens and determinants thereof are the targets of the autoimmune attack. Using comprehensive peptide libraries that cover the entire sequence of two major candidate autoantigens, GAD65 and proinsulin, we measured the in vivo frequencies of peptide-specific, IFN-gamma-producing memory T cells in 27 diabetic patients, 14 high risk individuals, and 15 partially HLA-matched healthy controls. Compared to the controls, both a higher number of determinants on the islet cell antigens were recognized and the frequencies of peptide specific cells were increased in patients and high risk individuals. Inclusion of signal enhancing anti-CD28 antibody further accentuated this difference. Considerable heterogeneity in peptide recognition was seen even in DRB1*04, DQB1*0302 matched individuals. Unlike its peptides, the GAD protein antigen did not recall a T cell memory response. The highly heterogeneous recognition of a multitude of peptide determinants on both autoantigens, occurring in the absence of protein recognition, and the low functional avidity of the memory cells involved jointly suggest that the autoimmune T cell repertoire in human type 1 diabetes primarily targets cryptic determinants engaged by determinant spreading.