Kenichi Furihata

Acquisition versus Loss of Helicobacter pylori Infection in Japan: Results from an 8-Year Birth Cohort Study

Studies of the pattern of change in the epidemiology of Helicobacter pylori infection are scarce. A longitudinal cohort study consisted of 644 children and adults, and two independent cross-sectional surveys were conducted in rural Japan between 1986 and 1994. The anti-H. pylori IgG seroconversion rates were 1.1% and 1% per year for children and adults, respectively. The seroreversion rate per year was 1.8% for children and 1.5% for adults. The cohort study was confirmed by the two cross-sectional studies. H. pylori prevalence fell in all age groups in both children (odds ratio [OR] = 0.5, 95% confidence interval [CI] = 0.2-1.0, P = .05) and adults (OR = 0.4, 95% CI = 0.3-0.6, P = .001). The rate of loss of H. pylori infection was greater than the acquisition. Data regarding acquisition and loss of H. pylori infection are critical to understanding the epidemiology of the infection and to developing treatment and vaccination strategies.

Influence of oral Helicobacter pylori on the success of eradication therapy against gastric Helicobacter pylori.

Background. The goal of this study was to see whether Helicobacter pylori (H. pylori) in the oral cavity might adversely affect the outcome of eradication therapy for gastric H. pylori.

Convulxin Binds to Native, Human Glycoprotein Ibα

Convulxin (CVX), a C-type snake protein from Crotalus durissus terrificus venom, is the quintessential agonist for studies of the collagen receptor, glycoprotein VI (GPVI) and its role in platelet adhesion to collagens. In this study, CVX, purified from venom, behaves as expected, i.e. it binds to platelet GPVI and recombinant human GPVI, induces platelet aggregation and platelet prothrombinase activity, and binds uniquely to GPVI in ligand blots of SDS-denatured proteins. Nonetheless, we find that CVX has a dual specificity for both GPVI and native but not denatured human GPIbα. First, CVX binds to human GPIbα expressed on the surface of CHO cells. Second, CVX binds weakly to murine platelet GPIbα but more strongly to human platelet GPIbα, as evidenced by comparative binding to wild-type, GPVI(–/–), FcRγ (–/–), and human GPIb transgenic mice. Third, the binding of CVX to human GPIbα is inhibited by soluble, recombinant human GPVI. Fourth, CVX binding to GPIbα is disrupted by phenylalanine substitutions at GPIbα tyrosine-276, tyrosine-278, and tyrosine-279, which also disrupts von Willebrand factor and α-thrombin binding to GPIbα. Fifth, CVX binding to GPIbα on Chinese hamster ovary cell transfectants is inhibited by function-blocking murine monoclonal anti-GPIbα antibodies. Lastly, CVX fails to bind to denatured GPIbα in detergent extracts of platelets. Three separate preparations of CVX (two purified by the authors; one obtained commercially) produced equivalent results. These results indicate that CVX exhibits dual specificity for both native GPIbα and GPVI. Furthermore, the binding site on GPIbα for CVX may be close to that for von Willebrand factor. Therefore, a contribution of GPIbα to CVX-induced platelet responses needs to be carefully re-evaluated.

Convulxin binds to native, human glycoprotein Ibα (GPIbα)

Convulxin (CVX), a C-type snake protein from Crotalus durissus terrificus venom, is the quintessential agonist for studies of the collagen receptor, glycoprotein VI (GPVI) and its role in platelet adhesion to collagens. In this study, CVX, purified from venom, behaves as expected, i.e. it binds to platelet GPVI and recombinant human GPVI, induces platelet aggregation and platelet prothrombinase activity, and binds uniquely to GPVI in ligand blots of SDS-denatured proteins. Nonetheless, we find that CVX has a dual specificity for both GPVI and native but not denatured human GPIbα. First, CVX binds to human GPIbα expressed on the surface of CHO cells. Second, CVX binds weakly to murine platelet GPIbα but more strongly to human platelet GPIbα, as evidenced by comparative binding to wild-type, GPVI(–/–), FcRγ (–/–), and human GPIb transgenic mice. Third, the binding of CVX to human GPIbα is inhibited by soluble, recombinant human GPVI. Fourth, CVX binding to GPIbα is disrupted by phenylalanine substitutions at GPIbα tyrosine-276, tyrosine-278, and tyrosine-279, which also disrupts von Willebrand factor and α-thrombin binding to GPIbα. Fifth, CVX binding to GPIbα on Chinese hamster ovary cell transfectants is inhibited by function-blocking murine monoclonal anti-GPIbα antibodies. Lastly, CVX fails to bind to denatured GPIbα in detergent extracts of platelets. Three separate preparations of CVX (two purified by the authors; one obtained commercially) produced equivalent results. These results indicate that CVX exhibits dual specificity for both native GPIbα and GPVI. Furthermore, the binding site on GPIbα for CVX may be close to that for von Willebrand factor. Therefore, a contribution of GPIbα to CVX-induced platelet responses needs to be carefully re-evaluated.

A novel splicing mutation in the ceruloplasmin gene responsible for hereditary ceruloplasmin deficiency with hemosiderosis.

Hereditary ceruloplasmin deficiency with hemosiderosis (aceruloplasminemia) is a newly recognized autosomal recessive disorder of copper-iron metabolism due to mutations in the ceruloplasmin (Cp) gene. We report here a novel mutation in the Cp gene in a 54-year-old Japanese woman with this disease. She showed clinical triad; diabetes mellitus, retinal degeneration and neurological disorder in her middle age. Laboratory findings were characteristic for no detectable serum ceruloplasmin and increased serum ferritin. Liver biopsy revealed excessive storage of iron in hepatocytes and magnetic resonance imaging of the brain was indicative of increased iron content in the basal ganglia, thalamus and dentate nucleus. The a-->g substitution at the splice acceptor site of the intron 6 (1209-2) caused a 8-bp deletion in Cp mRNA by defective splicing, resulting in a premature termination codon at the amino acid position 388. Truncation of Cp, even if effectively translated, may cause loss of its normal function because of drastic change in its triangular structure.

Influence of Platelet Collagen Receptor Polymorphisms on Risk for Arterial Thrombosis

CONTEXT Collagens are major components of the vascular subendothelium, and the interaction of platelets with collagens initiates normal hemostasis or pathologic arteriothrombosis. Genetic factors that affect the interaction of platelets with collagens could represent risk factors for either arteriothrombosis or excessive hemorrhage. In this regard, we first found that platelet levels of one of the major platelet collagen receptors, integrin alpha(2)beta(1), vary up to 10-fold in normal healthy individuals and that the higher-level phenotype is associated with allele 1 (807T) of the integrin alpha(2) gene. More recently, we found that there is roughly a fivefold range in platelet glycoprotein VI content among normal individuals, which may also influence risk for thromboembolism. OBJECTIVE To determine if genetic polymorphisms of platelet glycoproteins involved in collagen-related function are associated with higher risk for thrombotic disorders, such as coronary heart disease, myocardial infarction, or stroke. METHODS We examined the genetic mechanisms responsible for variation in expression levels of the collagen receptor integrin alpha(2)beta(1) and the potential influence of this variation on risk for thrombotic diseases. RESULTS We found that patients with arteriothrombotic diseases have a higher frequency of alpha(2) allele 1 (associated with higher levels of platelet integrin alpha(2)beta(1)). We further found that platelet glycoprotein VI content directly correlates with platelet prothrombinase activity, suggesting that a higher phenotype of platelet glycoprotein VI also may contribute to increased risk of arteriothrombotic diseases. CONCLUSION Genetic polymorphisms that influence the level or function of platelet collagen receptors need to be seriously considered as genetic risk factors for arteriothrombotic diseases.

A novel frameshift mutation in the McLeod syndrome gene in a Japanese family.

We report a novel mutation in the XK gene (XK) in a Japanese patient with McLeod syndrome. A 50-year-old man showed progressive muscular atrophy, choreic movement, elevated level of serum creatinine kinase, and acanthocytosis. The expression level of all the Kell antigens in erythrocyte was decreased and molecular analysis revealed a single-base (T) deletion at the nucleotide position 1095 in XK. This deletion caused a frameshift in translation, leading to a premature stop codon at the amino acid position 408. We conclude this single-base deletion causes defective Kx protein, which is responsible for the McLeod phenotype in this patient.

Human anti‐PlEl antibody recognizes epitopes associated with the alpha subunit of platelet glycoprotein Ib

Summary Together, a platelet‐reactive antibody in the serum of a polytransfused patient (proband) and a plateletreactive antibody in the serum of a mother of an infant with neonatal thrombocytopenia have served to establish the diallelic, platelet‐specific alloantigen system, PlE. We now provide evidence that the platelet‐specific antibody in the serum of the proband, anti‐PlEl, recognizes epitopes associated with the alpha subunit of glycoprotein (GP) Ib. By 51Cr release, platelets from two of three patients with the Bernard‐Soulier syndrome (BSS) responded sub‐normally to anti‐PlEl, and the apparently normal response of platelets from the last BSS patient was attributable to anti‐HLA‐A2 antibodies in the proband serum. These results suggested that the PlEl antigen is associated with the GPIb complex (glycoproteins Ib+IX) known to be absent from BSS platelets. This possibility was confirmed by ELISA using the purified GPIb complex or glycocalicin, the N‐terminal fragment of GPIb alpha produced by proteolysis with endogenous platelet calpain. as solid‐phase antigen. Anti‐PlEl antibody bound specifically to both the GPIb complex and glycocalicin. 3H‐labelled platelet membrane glycoproteins with apparent molecular weights of 130k, 25k, and 21k (under reduced conditions) corresponding to GPIb alpha, GPIb beta, and GPIX were immunoprecipitated by anti‐PlEl plasma. Finally, at a titre of 1:16, anti‐PlEl completely inhibited ristocetin‐induced platelet agglutination, a property of platelets mediated by GPIb.

Identification of two novel mutations in the OCRLI gene in Japanese families with Lowe syndrome

Kubota T, Sakurai A, Arakawa K, Shimazu M, Wakui K, Furihata K, Fukushima Y. Identification of two novel mutations in the OCRL1 gene in Japanese families with Lowe syndrome. Clin Genet 1998: 54: 199–202. 0 Munksgaard, 1998

A new histological procedure for re-evaluation of the serological test forHelicobacter pylori

To re-evaluate the accuracy of the serological test forHelicobacter pylori, fixation of biopsy specimens with Carnoys solution (preserving the mucous layer in tissue preparations) followed by immunohistochemical staining (a new histological procedure) was used as the reference histological method instead of 10% formalin fixation followed by hematoxylin-eosin staining (the conventional histological procedure). Biopsy specimens (antrum and body) from 114 patients with gastritis (including non-ulcer dyspepsia) or gastric and/or duodenal ulcers were obtained by endoscopy and used for both bacteriological culture and histological examination. Serum samples were taken from all patients at the time of endoscopy. The serum levels of specific IgG and IgA antibodies forHelicobacter pylori were measured by commercial enzyme immunoassay kits. The reliability of the IgG and IgA measurements was evaluated by analyzing receiver operating characteristic curves obtained using the two histological procedures. With the conventional histological procedure as the reference, the sensitivity and specificity levels of the serological test were 87.2% and 82.1%, respectively. With the new histological procedure as reference, sensitivity and specificity were 94% and 96.7%, respectively. The insufficient accuracy reported for the serological test could be due to false-positive or false-negative results obtained when the conventional histological procedure is used as the reference. The new histological procedure used here revealed that the serological test forHelicobacter pylori is more reliable than previously thought.