Is Periodontitis a Risk Factor for Cognitive Impairment and Dementia? A Case‐Control Study

Background : Dementia is a multi‐etiologic syndrome characterized by multiple cognitive deficits but not always by the presence of cognitive impairment. Cognitive impairment is associated with multiple non‐modifiable risk factors but few modifiable factors. Epidemiologic studies have shown an association between periodontitis, a potentially modifiable risk factor, and cognitive impairment. The objective of this study is to determine whether clinical periodontitis is associated with the diagnosis of cognitive impairment/dementia after controlling for known risk factors, including age, sex, and education level. Methods: A case‐control study was conducted in Granada, Spain, in two groups of dentate individuals aged >50 years: 1) cases with a firm diagnosis of mild cognitive impairment or dementia of any type or severity and 2) controls with no subjective memory loss complaints and a score >30 in the Phototest cognitive test (screening test for cognitive impairment). Periodontitis was evaluated by measuring tooth loss, plaque and bleeding indexes, probing depths, and clinical attachment loss (AL). Results: The study included 409 dentate adults, 180 with cognitive impairment and 229 without. A moderate and statistically significant association was observed between AL and cognitive impairment after controlling for age, sex, education level, oral hygiene habits, and hyperlipidemia (P = 0.049). No significant association was found between tooth loss and cognitive impairment. Conclusion: Periodontitis appears to be associated with cognitive impairment after controlling for confounders such as age, sex, and education level.     

Prognostic significance of terminal transferase activity in childhood acute lymphoblastic leukemia: a prospective analysis of 164 patients

Whether the level of terminal deoxynucleotidyl transferase (TdT) activity in mononuclear cells from bone marrow and peripheral blood has prognostic significance has been analyzed prospectively in 164 children with T and non-T, non-B marked acute lymphoblastic leukemia (ALL). TdT was measured at diagnosis to assess its value as a predictor of duration of remission and length of survival. It was measured repeatedly during remission to assess whether it could predict relapse. Ninety-seven percent of the children achieved a complete remission of their disease, and 40% relapsed during the study. The level of TdT activity in blasts at diagnosis varied 1000-fold from patient to patient. There was no statistically significant relationship between TdT activity in cells at diagnosis and the achievement of complete remission, the duration of remission, or length of survival. TdT activity was significantly increased in the bone marrow of 65% of patients at the time of marrow morphological relapse, but was rarely increased in marrow from patients with isolated testicular or central nervous system relapse. Wide fluctuations in TdT activity were characteristically seen in mononuclear cells from the marrow and peripheral blood of patients with ALL at all stages of their disease. An isolated high value of TdT activity in the bone marrow or peripheral blood cannot be taken as evidence of impending relapse. Quantitative measurements of TdT activity alone on mononuclear cells from bone marrow and peripheral blood are helpful in differential diagnosis, but cannot guide therapy of children with ALL.     

An antifibrin monoclonal antibody useful in immunoscintigraphic detection of thrombi

Balb/c mice were immunized with human plasmin-generated fibrinogen degradation product Y. Spleen cells were fused with P3X63-Ag8.653 myeloma cells. A clone (Y22) was found that produces monoclonal antibodies (MoAbs) with a strong reactivity with human fibrin and only a weak reactivity with fibrinogen in an enzyme immunoassay (EIA). Y22 also reacts with fibrin of rabbits, rats, sheep, and dogs. The antibodies are of the IgG1 kappa-type and appear to be directed against a conformation-dependent epitope in the D-domain of fibrin. Experiments with 99mTc-labeled Y22 in vitro show that Y22 binds rapidly to forming clots. 99mTc-Y22 also binds to preformed plasma clots in a plasma milieu, even in the presence of high concentrations of heparin. Clot localization experiments in rabbits and rats confirm the high fibrin specificity and the potential of 99mTc-Y22 for thrombus imaging in vivo.     

Platelet interactions with fibronectin: divalent cation-independent platelet adhesion to the gelatin-binding domain of fibronectin

Divalent cation-dependent platelet adhesion to fibronectin (FN) is mediated by the integrin receptors alpha 5 beta 1 (GP Ic-IIa) and alpha IIb beta 3 (GP IIb-IIIa), which recognize the RGD (Arg-Gly-Asp) sequence in the cell-binding domain. However, FN can also support divalent cation-independent platelet adhesion. To determine which domain of FN mediates divalent cation-independent adhesion, proteolysis with thermolysin and affinity chromatography were used to isolate the cell-binding, gelatin-binding, and heparin-binding domains of FN. Unactivated and thrombin-activated platelets adhered to intact FN and the 45-Kd gelatin-binding domain in the presence of either Ca2+ or EDTA. Platelet spreading was mediated only by the 105-Kd cell-binding domain and required divalent cations. The heparin-binding domains did not support platelet adhesion. Reduction of intrachain disulfide bonds or removal of carbohydrate side chains on the gelatin-binding domain did not alter the ability to support platelet adhesion. Divalent cation- independent adhesion to the 45-Kd gelatin-binding domain was not inhibited by RGDS (Arg-Gly-Asp-Ser) synthetic peptides or monoclonal antibodies (MoAbs) directed against known platelet receptors. We conclude that platelets can adhere but not spread on the gelatin- binding domain of FN by a novel divalent cation-independent mechanism.     

Synergistic inhibition of the intrinsic factor X activation by protein S and C4b-binding protein

The complement protein C4b-binding protein plays an important role in the regulation of the protein C anticoagulant pathway. C4b-binding protein can bind to protein S, thereby inhibiting the cofactor activity of protein S for activated protein C. In this report, we describe a new role for C4b-binding protein in coagulation. We observed inhibition of the intrinsic factor X activating reaction by the complex of C4b- binding protein and protein S. At the plasma concentration of protein S, the factor X activation was inhibited for 50% and addition of C4b- binding protein led to a potentiation of the inhibition to almost 90%. Because C4b-binding protein alone had no effect on the activation of factor X, we hypothesized that binding of C4b-binding protein to protein S was a prerequisite for optimal inhibition of factor X activation. C4b-binding protein lacking the beta-chain, which is unable to bind to protein S, did not potentiate the inhibitory effect of protein S. In an earlier study, we observed that C4b-binding protein increased the binding affinity of protein S for factor VIII. Therefore, a possible interaction of C4b-binding protein with factor VIII was investigated. C4b-binding protein bound to factor VIII and to thrombin activated factor VIII in a saturable and specific way. Also, factor VIII in complex with von Willebrand factor was able to bind C4b-binding protein. The beta-chain of C4b-binding protein was not required for the interaction with factor VIII because C4b-binding protein lacking the beta-chain also bound to factor VIII. Monoclonal antibodies directed against the alpha-chain of C4b-binding protein inhibited the binding to factor VIII, whereas monoclonal antibodies directed against the beta- chain had no effect on the binding to factor VIII. This finding indicates that the binding site for factor VIII on C4b-binding protein is localized on the alpha-chains of C4b-binding protein. The potentiation by C4b-binding protein of the inhibition of the factor X activation by protein S was blocked by a monoclonal antibody directed against the alpha-chain of C4b-binding protein. This finding indicates that the potentiation of the inhibitory effect of protein S was mediated via an interaction of C4b-binding protein with factor VIII. C4b-binding protein did not bind to factor V and was not able to potentiate the inhibitory effect of protein S on prothrombinase activity.(ABSTRACT TRUNCATED AT 400 WORDS)     

On the role of von Willebrand factor in promoting platelet adhesion to fibrin in flowing blood

Platelet adhesion to fibrin at high shear rates depends on both the glycoprotein (GP) IIb:IIIa complex and a secondary interaction between GPIb and von Willebrand factor (vWF). This alternative link between platelets and vWF in promoting platelet adhesion to fibrin has been examined in flowing whole blood with a rectangular perfusion chamber. Optimal adhesion required both platelets and vWF, as shown by the following observations. No binding of vWF could be detected when plasma was perfused over a fibrin surface or when coated fibrinogen was incubated with control plasma in an enzyme-linked immunosorbent assay. However, when platelets were present during perfusion, interactions between vWF and fibrin could be visualized with immunoelectron microscopy. Exposure of fibrin surfaces to normal plasma before perfusion with severe von Willebrand's disease blood did not compensate for the presence of plasma vWF necessary for adhesion. vWF mutants in which the GPIIb:IIIa binding site was mutated or the GPIb binding site was deleted showed that vWF only interacts with GPIb on platelets in supporting adhesion to fibrin and not with GPIIb:IIIa. Complementary results were obtained with specific monoclonal antibodies against vWF. Thus, vWF must first bind to platelets before it can interact with fibrin and promote platelet adhesion. Furthermore, only GPIb, but not GPIIb:IIIa is directly involved in this interaction of vWF with platelets.     

Association of a chromosomal 3;21 translocation with the blast phase of chronic myelogenous leukemia

An identical reciprocal translocation between the long arms of chromosomes 3 and 21 with breakpoints in bands 3q26 and 21q22, t(3;21)(q26;q22), was found in three male patients with the blast phase of chronic myelogenous leukemia (CML). The abnormality was clonal in all three patients and was always accompanied by either a standard or variant 9;22 translocation resulting in a Philadelphia chromosome (Ph1). In two cases, the t(3;21) was the only abnormality other than a t(9;22) in the primary clone. Serial studies of one patient demonstrated that the t(3;21) occurred as a result of clonal evolution near the time of development of the blast phase. We have not observed the t(3;21) in greater than 500 patients with CML in the chronic phase. Thus, the t(3;21) is a new recurring cytogenetic abnormality associated with the blast phase of CML.     

High glucocorticoid receptor content of leukemic blasts is a favorable prognostic factor in childhood acute lymphoblastic leukemia

We have previously shown that the number of glucocorticoid receptors (GR) per cell in malignant lymphoblasts from children with newly diagnosed pre-B- and early pre-B-cell acute lymphoblastic leukemia (ALL) has a positive correlation with the probability of successful remission induction (Quddus et al, Cancer Res, 45:6482, 1985). We report now on the long-term outcome for these patients treated on a single protocol with 3 different treatment arms, all of which included glucocorticoid pulses during maintenance therapy. GR were quantitated in leukemic cells from 546 children with ALL at the time of diagnosis. Immunophenotyping studies were performed on all specimens. Prior studies showed that in pre-B- and early pre-B-cell ALL, successful remission induction was associated with a median GR number of 9,900 sites/cell, whereas induction failure was associated with a median receptor number of 4,800 sites/cell. Long-term follow-up of these patients shows an association between higher GR number and improved prognosis. The 5-year event-free survival of 61.0% (SE 2.8%) for patients whose leukemic cells had greater than 8,000 receptors/cell and 47.3% (SE 3.3%) for those with less than 8,000 receptors/cell is significantly different (P < .001). This difference remains significant when adjusted multivariately for blast immunophenotype and clinical risk factors (P < .001) or for treatment type (P < .001). We conclude that GR number greater than 8,000 sites/leukemic cell is a favorable prognostic marker for children with acute lymphocytic leukemia. This finding offers deeper insights into molecular mechanisms of anti- leukemia therapy and suggests that manipulation of steroid receptor number might augment the antitumor response, thus opening new avenues for basic and clinical research.     

Liver transplantation for hepatitis C-associated cirrhosis in a single Australian centre: Referral patterns and transplant outcomes

During the study period, 63 patients with hepatitis C virus (HCV) cirrhosis were referred to our unit for liver transplantation. All cases referred and transplanted were retrospectively examined. Eighty-six per cent of referred patients were male, 35% consumed alcohol in the harmful hazardous range, 13% were infected with hepatitis B and 7% had hepatocellular carcinoma. Patients with sporadic infection were more likely to be born outside Australia and were an average of 10 years older than those with HCV acquired via intravenous drug use (P< 0.001). However, patients were an average of 12 years younger at referral if they consumed harmful amounts of alcohol than if they abstained (P = 0.002). We examined the impact of HCV on the outcome of 28 patients who underwent liver transplantation (mean follow up 25 months; range 3–76 months). The use of OKT3, HCV genotype and hepatitis B status were examined for their effect on HCV-related graft dysfunction. Three year survival was 84%, equivalent to a control group. Chronic HCV-related graft dysfunction occurred in 15 (56%) patients, of whom 10 had an asymptomatic elevation in serum amino transferase, two had cholestatic hepatitis and three had severe hepatitis C that progressed onto chronic rejection. Hepatitis C virus genotype 1b tended to be associated with HCV graft dysfunction (5/6 type 1b vs 10/16 in non-type 1b). In conclusion, HCV is an increasingly common-indication for liver transplantation. Alcohol and hepatitis B were frequently occurring cofactors in the referral cohort. Most patients referred were male, although the reason why is not clear. Transplantation offers a good medium-term outcome, despite the high incidence of HCV-associated graft dysfunction.     

Ribozyme-mediated inhibition of bcr-abl gene expression in a Philadelphia chromosome-positive cell line

The bcr-abl fusion gene is the molecular counterpart of the Philadelphia chromosome (Ph1) and is directly involved in the pathogenesis of Ph1+ leukemia. Inhibition of bcr-abl gene expression may have profound effects on the cell biology of Ph1+ cells, as recent experiments with antisense oligonucleotides have shown. In this study we have designed and synthesized a unique ribozyme that is directed against bcr-abl mRNA. The ribozyme cleaved bcr-abl mRNA in a cell-free in vitro system. A DNA-RNA hybrid ribozyme was then incorporated into a liposome vector and transfected into EM-2 cells, a cell line derived from a patient with blast crisis of chronic myelogenous leukemia. The ribozyme decreased levels of detectable bcr-abl mRNA in these cells, inhibited expression of the bcr-abl gene product, p210bcr-abl, and inhibited cell growth. This anti-bcr-abl ribozyme may be a useful tool to study the cell biology of Ph1+ leukemia and may ultimately have therapeutic potential in treating patients with Ph1 leukemias.