Immune thrombocytopenic purpura associated with rheumatoid arthritis: case report

A 54-year-old Japanese woman was diagnosed with rheumatoid arthritis (RA) in 1995 on the basis of symmetric effusive polyarthritis, morning stiffness, and strongly positive rheumatoid factor. She had received low-dose prednisolone, indomethacin, methotrexate (MTX), and cyclophosphamide (CPA), at least, over 4 years before the current admission and showed partial improvement of polyarthralgia. In November 2002, she suddenly developed thrombocytopenia (platelet count was 0.3×10⁴ mm^–3) with purpura and was diagnosed with immune thrombocytopenic purpura (ITP). As she had refractory ITP, the administration of pulsed high-dose dexamethasone (DEX) therapy was started, resulting in the complete remission of ITP. The present paper reports that pulsed high-dose DEX therapy was useful for the treatment of refractory ITP associated with RA.     

A prospective and comparative cohort study on efficacy and drug resistance during long-term lamivudine treatment for various stages of chronic hepatitis B and cirrhosis

Background and Aims: A prospective , non‐randomized cohort study on long‐term lamivudine treatment , comparing efficacy, drug resistance, and prognosis for various stages of chronic hepatitis B virus (HBV)–related liver disease was performed to elucidate the significance and indication of lamivudine for individual patients at each stage of disease. Methods: A total of 158 cases consisting of 87 chronic hepatitis, 28 compensated cirrhosis, and 43 decompensated cirrhosis, with serum HBV‐DNA > 5 log₁₀ copies/mL and with elevated alanine aminotransferase (ALT) over twice the upper normal limit or complications of hepatic insufficiency, were administered 100 mg of lamivudine daily and monitored for HBV markers, biochemistry, and prognosis. Results: Lamivudine reduced HBV‐DNA and ALT equally in all groups. Serum albumin, prothrombin time (%), and platelet count increased in all groups. The increased margin of albumin was the highest in the decompensated cirrhosis and higher in the compensated cirrhosis than the chronic hepatitis groups. Cumulative incidence of virologic breakthrough was 16%, 42%, 49%, and 53% at 12, 24, 36, and 48 months, respectively, and the strongest predictive factor for lamivudine resistance was persistent HBV‐DNA at 3 months. Ascites, encephalopathy, and jaundice improved in the majority of patients with decompensated cirrhosis. On the other hand, hepatic failure developed or deteriorated in 10 patients after virologic breakthrough, and nine of them had decompensated cirrhosis. Conclusions: Lamivudine was effective in reducing HBV‐DNA and improving hepatic reserve at all stages and was most beneficial and significant for decompensated cirrhosis. Meanwhile, close monitoring of viral load and immediate rescue treatment for lamivudine resistance is necessary to prevent hepatic failure in decompensated cirrhosis.     

Relationships between polymorphisms of the human serum paraoxonase gene and insulin sensitivity in Japanese patients with type 2 diabetes

Human serum paraoxonase (PON1), which is associated with HDL, is an esterase and has been shown to reduce the susceptibility of LDL to lipid peroxidation. The objective of the study was to determine whether genetic polymorphisms of the PON1 gene are associated with insulin sensitivity. Forty-eight Japanese patients with type 2 diabetes were recruited, and euglycemic hyperinsulinemic clamp was performed to assess insulin sensitivity. The PON1 promoter polymorphism C(-108)T was determined by direct sequencing, and the coding region polymorphism Q192R was determined by polymerase chain reaction and digestion of the amplified fragments. No association was observed between the Q192R polymorphism and the glucose infusion rate (GIR), whereas GIR increased with the following order of genotypes: -108TT < -108CT < and -108CC (4.2+/-1.6, 5.1+/-2.5, and 6.9+/-2.5 mg kg(-1) min(-1), respectively; P<0.02, ANCOVA). Stepwise regression analysis revealed that the C(-108)T polymorphism significantly contributed to the GIR. It has been reported that oxidative stress attenuates insulin signaling in vitro. The PON1 promoter polymorphism C(-108)T may influence insulin sensitivity by modulating serum antioxidant capacity.     

Aberrant calcium signaling by transglutaminase-mediated posttranslational modification of inositol 1,4,5-trisphosphate receptors

The inositol 1,4,5-trisphosphate receptor (IP₃R) in the endoplasmic reticulum mediates calcium signaling that impinges on intracellular processes. IP₃Rs are allosteric proteins comprising four subunits that form an ion channel activated by binding of IP₃ at a distance. Defective allostery in IP₃R is considered crucial to cellular dysfunction, but the specific mechanism remains unknown. Here we demonstrate that a pleiotropic enzyme transglutaminase type 2 targets the allosteric coupling domain of IP₃R type 1 (IP₃R1) and negatively regulates IP₃R1-mediated calcium signaling and autophagy by locking the subunit configurations. The control point of this regulation is the covalent posttranslational modification of the Gln2746 residue that transglutaminase type 2 tethers to the adjacent subunit. Modification of Gln2746 and IP₃R1 function was observed in Huntington disease models, suggesting a pathological role of this modification in the neurodegenerative disease. Our study reveals that cellular signaling is regulated by a new mode of posttranslational modification that chronically and enzymatically blocks allosteric changes in the ligand-gated channels that relate to disease states.Ligand-gated ion channels function by allostery that is the regulation at a distance; the allosteric coupling of ligand binding with channel gating requires reversible changes in subunit configurations and conformations (1). Inositol 1,4,5-trisphosphate receptors (IP₃Rs) are ligand-gated ion channels that release calcium ions (Ca²⁺) from the endoplasmic reticulum (ER) (2, 3). IP₃Rs are allosteric proteins comprising four subunits that assemble a calcium channel with fourfold symmetry about an axis perpendicular to the ER membrane. The subunits of three IP₃R isoforms (IP₃R1, IP₃R2, and IP₃R3) are structurally divided into three domains: the IP₃-binding domain (IBD), the regulatory domain, and the channel domain (3–6). Fitting of the IBD X-ray structures (7, 8) to a cryo-EM map (9) indicates that the IBD activates a remote Ca²⁺ channel by allostery (8); however, the current X-ray structure only spans 5% of each tetramer, such that the mechanism underlying allosteric coupling of the IBD to channel gating remains unknown.The IP₃R in the ER mediates intracellular calcium signaling that impinges on homeostatic control in various subsequent intracellular processes. Deletion of the genes encoding the type 1 IP₃R (IP₃R1) leads to perturbations in long-term potentiation/depression (3, 10, 11) and spinogenesis (12), and the human genetic disease spinocerebellar ataxia 15 is caused by haploinsufficiency of the IP₃R1 gene (13–15). Dysregulation of IP₃R1 is also implicated in neurodegenerative diseases including Huntington disease (HD) (16–18) and Alzheimer’s disease (AD) (19–22). IP₃Rs also control fundamental cellular processes—for example, mitochondrial energy production (23, 24), autophagy regulation (24–27), ER stress (28), hepatic gluconeogenesis (29), pancreatic exocytosis (30), and macrophage inflammasomes (31). On the other hand, excessive IP₃R function promotes cell death processes including apoptosis by activating mitochondrial or calpain pathways (2, 17). Considering these versatile roles of IP₃Rs, appropriate IP₃R structure and function are essential for living systems, and aberrant regulation of IP₃R closely relates to various diseases.Several factors such as cytosolic molecules, interacting proteins, and posttranslational modifications control the IP₃-induced Ca²⁺ release (IICR) through allosteric sites in IP₃Rs. Cytosolic Ca²⁺ concentrations strictly control IICR in a biphasic manner with activation at low concentrations and inhibition at higher concentrations. The critical Ca²⁺ sensor for activation is conserved among the three isoforms of IP₃ and ryanodine receptors, and this sensor is located in the regulatory domain outside the IBD and the channel domain (32). A putative ATP regulatory region is deleted in opisthotonos mice, and IICR is also regulated by this mutation in the regulatory domain (33). Various interacting proteins, such as cytochrome c, Bcl-2-family proteins, ataxin-3, huntingtin (Htt) protein, Htt-associated protein 1A (HAP1A), and G-protein–coupled receptor kinase-interacting protein 1 (GIT1), target allosteric sites in the carboxyl-terminal tail (3–5). The regulatory domain and the carboxyl-terminal tail also undergo phosphorylation by the protein kinases A/G and B/Akt and contain the apoptotic cleavage sites for the protease caspase-3 (4, 5). These factors allosterically regulate IP₃R structure and function to control cellular fates; therefore, understanding the allosteric coupling of the IBD to channel gating will elucidate the regulatory mechanism of these factors.Transglutaminase (TG) catalyses protein cross-linking between a glutamine (Gln) residue and a lysine (Lys) residue via an N^ε-(γ-glutamyl)lysine isopeptide bond (34, 35). TG type 2 (TG2) is a Ca²⁺-dependent enzyme with widespread distribution and is highly inducible by various stimulations such as oxidative stress, cytokines, growth factors, and retinoic acid (RA) (34, 35). TG2 is considered a significant disease-modifying factor in neurodegenerative diseases including HD, AD, and Parkinson’s diseases (PD) (34, 36–45) because TG2 might enzymatically stabilize aberrant aggregates of proteins implicated in these diseases—that is, mutant Htt, β-amyloid, and α-synuclein; however, the causal role of TG2 in Ca²⁺ signaling in brain pathogenesis has been unclear. Ablation of TG2 in HD mouse models is associated with increased lifespan and improved motor function (46, 47). However, TG2 knockout mice do not show impaired Htt aggregation, suggesting that TG2 may play a causal role in these disorders rather than TG2-dependent cross-links in aberrant protein aggregates (47, 48).In this study, we discovered a new mode of chronic and irreversible allosteric regulation in IP₃R1 in which covalent modification of the receptor at Gln2746 is catalyzed by TG2. We demonstrate that up-regulation of TG2 modifies IP₃R1 structure and function in HD models and propose an etiologic role of this modification in the reduction of neuronal signaling and subsequent processes during the prodromal state of the neurodegenerative disease.     

Adenosquamous carcinoma of the pancreas

A 58-year-old Japanese man was admitted complaining of abdominal pain. An abdominal computed tomography examination demonstrated a tumor in the head of the pancreas and multiple calcifications. A laparotomy was performed and the tumor was removed by Whipple's operation. Histologically, the neoplasm that invaded the duodenal wall and the papilla of Vater was composed of nests of malignant squamous cells with intercellular bridges and showed the formation of keratinized pearls with a small area of concurrently neoplastic glandular and squamous elements. On the basis of these features, the diagnosis of adenosquamous carcinoma of the pancreas was made. The patient died 18 months after the operation. The neoplastic behavior of this rare primary pancreatic carcinoma is similar to that of duct cell carcinoma as well as pure squamous cell carcinoma of the pancreas. As the pancreas can be the target of metastases of squamous carcinomas from other organs it is wise to be aware of this rare entity.     

Serum paraoxonase (PON1) concentration in patients undergoing hemodialysis

Cardiac death from atherosclerosis is common in patients undergoing hemodialysis. Although the enzymic activity of human serum paraoxonase (PON1) has been reported to be decreased in such patients, serum PON1 concentrations have not been measured. We investigated serum PON1 concentrations in 81 patients undergoing hemodialysis and 103 age-matched healthy subjects using an enzyme immunoassay. The PON1 concentration was significantly lower in the patient group than the control group (mean +/- SD: 6.78 +/- 3.56 vs 18.01 +/- 4.55 U/ml, respectively. p < 0.0001). There were no significant relationships between serum PON1 concentrations and the PON1 genetic polymorphisms, 55Leu/Met (L/M) and 192Gln/Arg (Q/R). The concentration adjusted for HDL-cholesterol or apolipoprotein A-I was also lower in the patient group. However, the specific activities (enzyme activity divided by the PON1 concentration) of paraoxonase and arylesterase were increased in the patient group compared with the control group. In the male patients, but not the female patients, PON1 concentrations were significantly lower in subjects with than without coronary heart disease (CHD) (mean +/- SD: 4.48 +/- 2.77 vs 7.34 +/- 3.22 U/ml, respectively. p < 0.01). In conclusion, the serum PON1 concentration in hemodialyzed patients was significantly decreased, resulting in an attenuation of PON1 enzymic activity. This decrease may be in part involved in the development of cardiovascular disease.     

Flow cytometric analysis of de novo acute lymphoblastic leukemia in childhood: report from the Japanese Pediatric Leukemia/Lymphoma Study Group

Although the antigen expression patterns of childhood acute lymphoblastic leukemia (ALL) are well known, little attention has been given to standardizing the diagnostic and classification criteria. We retrospectively analyzed the flow cytometric data from a large study of antigen expression in 1,774 children with newly diagnosed ALL in JPLSG. T- and B-lineage ALL accounted for 13 and 87% of childhood ALL cases, respectively. Cytoplasmic CD3 and CD7 antigens were positive in all T-ALL cases. More than 80% of T-ALL cases expressed CD2, CD5 and TdT. In B-lineage ALL, the frequencies of early pre-B, pre-B, transitional pre-B and B-ALL were 81, 15.5, 0.6 and 2.9%, respectively. More than 90% of early pre-B ALL cases expressed CD19, CD79a, CD22, CD10 and TdT. CD34 was expressed in three-fourths of early pre-B ALL cases. The frequencies of TdT and CD34 expression were lower in pre-B ALL than in early pre-B ALL. B-ALL showed less frequent expression of CD22, CD10, CD34 and TdT than other B-lineage ALL cases. Expression of CD13 and CD33, aberrant myeloid antigens, was significantly more frequently associated with B-lineage ALL than with T-ALL. Based on this retrospective study of antigen expression in 1,774 de novo childhood ALL cases in JPLSG, we propose standardized clinical guidelines for the immunophenotypic criteria for diagnosis and classification of pediatric ALL.     

Nucleotide sequence of the adenovirus type 40 inverted terminal repeat: close relation to that of adenovirus type 5

Human adenovirus type 40 (Ad40) is a pathogen that causes acute infantile gastroenteritis. Ad40 has the distinct characteristic of being difficult to propagate in conventional cultured human cells. The nucleotide sequence of the inverted terminal repeat (ITR) of Ad40, which includes the origin of adenoviral DNA replication, was determined using recombinant plasmid DNA. By using our newly developed program to express the ITR homologies simply, we found that the ITR of Ad40, which is 163 nucleotides long, was related most closely to that of adenovirus type 5, which replicates efficiently.