Genghis Khan (Gek) as a putative effector for Drosophila Cdc42 and regulator of actin polymerization

The small GTPases Cdc42 and Rac regulate a variety of biological processes, including actin polymerization, cell proliferation, and JNK/mitogen-activated protein kinase activation, conceivably via distinct effectors. Whereas the effector for mitogen-activated protein kinase activation appears to be p65^PAK, the identity of effector(s) for actin polymerization remains unclear. We have found a putative effector for Drosophila Cdc42, Genghis Khan (Gek), which binds to Dcdc42 in a GTP-dependent and effector domain-dependent manner. Gek contains a predicted serine/threonine kinase catalytic domain that is 63% identical to human myotonic dystrophy protein kinase and has protein kinase activities. It also possesses a large coiled-coil domain, a putative phorbol ester binding domain, a pleckstrin homology domain, and a Cdc42 binding consensus sequence that is required for its binding to Dcdc42. To study the in vivo function of gek, we generated mutations in the Drosophila gek locus. Egg chambers homozygous for gek mutations exhibit abnormal accumulation of F-actin and are defective in producing fertilized eggs. These phenotypes can be rescued by a wild-type gek transgene. Our results suggest that this multidomain protein kinase is an effector for the regulation of actin polymerization by Cdc42.     

Direct activation of neutrophil chemiluminescence by rheumatoid sera and synovial fluid.

The majority of paired sera and synovial fluids from 21 patients with rheumatoid arthritis produced a rapid chemiluminescent response when incubated with human neutrophils. Synovial fluid gave considerably higher responses than the paired serum specimen. In contrast little or no response was found with paired sera and joint fluid taken from patients with gout, psoriasis, and osteoarthritis and with sera from healthy donors. A similar chemiluminescent response was observed when neutrophils were preincubated with large aggregates of heated human gammaglobulin (HAGG), which were used as a model of immune complexes. Smaller nonreactive aggregates of gammaglobulin became reactive after preincubation with a purified monoclonal rheumatoid factor (mRF) which had a high avidity for aggregated IgG. The addition of this monoclonal rheumatoid factor also caused enhancement of chemiluminescence by rheumatoid sera. Further evidence suggesting that the active material found in these rheumatoid specimens contained complexed immunoglobulin was obtained by indirect immunofluorescence. Neutrophils developed intracellular immunoglobulin inclusions after preincubation in reactive rheumatoid sera but not with nonreactive or normal sera. However, activation of neutrophil chemiluminescence by rheumatoid specimens did not correlate significantly with levels of rheumatoid factor or immune complexes suggesting that the activating complexes were of a particular type. In conclusion we have shown the direct activation of neutrophil chemiluminescence by rheumatoid sera synovial fluid and suggest that the activation is caused by large IgG-containing immune complexes. It is possible that this activation may have important implications in the immunopathogenesis of the rheumatoid inflammatory process.     

Dynamics of telomere shortening in neutrophils and T lymphocytes during ageing and the relationship to skewed X chromosome inactivation patterns

Human haemopoiesis undergoes profound changes throughout life, resulting in compromised regenerative capacity of haemopoietic stem cells. It has been suggested that telomere shortening results in senescence of haemopoietic stem cell subsets and may influence the balance between stem cell renewal and proliferation. Telomere length and telomerase activity was measured in whole blood leucocytes, neutrophils and T cells from cord blood and individuals aged from 1 year to 96 years. Rapid telomere shortening [700 base pairs (bp)] was demonstrated in the first year of life, followed by a gradual decline of 31 bp/year. T cells were shown to have longer telomeres than neutrophils (mean difference 372 bp, P = < 0.001) but demonstrated similar rates of shortening (20 +/- 0.3 bp/year vs. 22 +/- 0.3 bp/year). Telomerase was detectable in T cells but not in neutrophils, suggesting that telomerase is not the rate-limiting step for regulation of telomere length in haemopoietic cells. Stem cell utilization as measured by X chromosome inactivation patterns was found to be independent of telomere length. This supports the concept that age-dependent skewed haemopoiesis is the result of random stem cell loss or X-allelic exclusion rather than telomeric senescence. These studies provide insight into the ageing process and a reference point for evaluating replicative stress in individuals of different age groups.     

Mechanism of antithrombin III inhibition of factor VIIa/tissue factor activity on cell surfaces. Comparison with tissue factor pathway inhibitor/factor Xa-induced inhibition of factor VIIa/tissue factor activity

Recent studies have shown that antithrombin III (AT III)/heparin is capable of inhibiting the catalytic activity of factor VIIa bound either to relipidated tissue factor (TF) in suspension or to TF expressed on cell surfaces. We report studies of the mechanism of which by AT III inhibits factor VIIa bound to cell surface TF and compare this inhibitory mechanism with that of tissue factor pathway inhibitor (TFPI)-induced inhibition of factor VIIa/TF. AT III alone and AT III/heparin to a greater extent reduced factor VIIa bound to cell surface TF. Our data show that the decrease in the amount of factor VIIa associated with cell surface TF in the presence of AT III was the result of (1) accelerated dissociation of factor VIIa from cell surface TF after the binding of AT III to factor VIIa/TF complexes and (2) the inability of the resultant free factor VIIa-AT III complexes to bind effectively to a new cell surface TF site. Binding of TFPI/factor Xa to cell surface factor VIIa/TF complexes markedly decreased the dissociation of factor VIIa from the resultant quaternary complex of factor VIIa/TF/TFPI/factor Xa. Addition of high concentrations of factor VIIa could reverse the AT III-induced inhibition of cell surface factor VIIa/TF activity but not TFPI/factor Xa-induced inhibition of factor VIIa/TF activity.     

Phylogenetic sequence analysis, recombinant expression, and tissue distribution of a channel catfish estrogen receptor beta

An estrogen receptor beta (ERbeta) cDNA fragment was amplified by RT-PCR of total RNA extracted from liver and ovary of immature channel catfish. This cDNA fragment was used to screen an ovarian cDNA library made from an immature female fish. A clone was obtained that contained an open reading frame encoding a 575-amino-acid protein with a deduced molecular weight of 63.9 kDa. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of channel catfish ERbeta on the basis of 25 full-length teleost and tetrapod ER sequences. The consensus tree obtained indicated the existence of two major vertebrate ER subtypes, alpha and beta. Within each subtype, and in accordance with established phylogenetic relationships, teleost and tetrapod ER were monophyletic confirming the results of a previous analysis (Z. Xia et al., 1999, Gen. Comp. Endocrinol. 113, 360-368). Extracts of COS-7 cells transfected with channel catfish ERbeta cDNA bound estrogen with high affinity (K(d) = 0.21 nM) and specificity. The affinity of channel catfish ERbeta for estrogen was higher than previously reported for channel catfish ERalpha. As determined by qualitative RT-PCR, the tissue distributions of ERalpha and ERbeta were similar but not identical. Both ER subtypes were present in ovary and testis. ERalpha was found in all other tissues examined from juvenile and mature fish of both sexes. ERbeta was also found in most tissues except, in most cases, whole blood and head kidney. Interestingly, the pattern of expression of ER subtypes in head kidney always corresponded to the pattern in whole blood. In conclusion, we isolated a channel catfish ERbeta with ligand-binding affinity and tissue expression patterns different from ERalpha. Also, we confirmed the validity of our previously proposed general classification scheme for vertebrate ER into alpha and beta subtypes and within each subtype, into teleost and tetrapod clades.     

Improper positioning of the elevator lever of duodenoscopes may lead to sequestered bacteria that survive disinfection by automated endoscope reprocessors

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Cytomegalovirus immune plasma in bone marrow transplant recipients

The effects of passive immunization on cytomegalovirus infection and interstitial pneumonia in marrow transplants were evaluated in a randomized, controlled trial. Twenty-four patients received cytomegalovirus immune plasma before and after transplantation, and 24 patients were controls. Although the incidence of cytomegalovirus infection was similar in the control and plasma groups, symptomatic infection (12 of 24 versus five of 24, p = 0.07) and interstitial pneumonia (11 of 24 versus five of 24, p = 0.12) occurred less frequently in the group receiving plasma. Cytomegalovirus infection occurred in 11 of 13 recipients of leukocyte transfusions and in 16 of 35 patients not given leukocyte transfusions (p = 0.02). Among patients not given leukocyte transfusions, the incidence of cytomegalovirus infection was similar in the control and plasma groups, but symptomatic infection (eight of 18 versus one of 17, p = 0.03) and interstitial pneumonia (nine of 18 versus one of 17, p = 0.01) were significantly less in the group receiving plasma. These results suggest that passive immunization modifies cytomegalovirus infection in humans and prevents interstitial pneumonia in marrow transplants especially when leukocyte transfusions are not used.     

Controversies in the therapy of acute myelogenous leukemia

In the past 10 years, there has been substantial progress in the treatment of patients with acute myelogenous leukemia. Intensive induction chemotherapy and consolidation chemotherapy have increased complete remission rates from 25 percent to more than 70 percent and have extended median survival from six months to more than two years. Attempts to prolong remission with maintenance chemotherapy, immunotherapy, and central nervous system prophylaxis have been less successful. Recent data suggest that the use of intensification chemotherapy or bone marrow transplantation in patients in remission may further reduce or eliminate residual leukemia. As a result of one or more of these advances an increasing proportion of patients, up to 25 percent in some series, are alive and free of disease three to five years following diagnosis. Most data indicate that some of these patients may be cured. In this article, we review the therapeutic interventions responsible for this substantial increase in survival in what was previously a uniformly fatal disease. Recent advances are discussed as are controversies in management and future directions.     

The dynamic relationship between cognitive function and walking speed: the English Longitudinal Study of Ageing

Cognitive deficiency and oxidative stress have been well documented in aging and in neurodegenerative disorders such as Alzheimer’s disease. In this study, we assessed the therapeutic effect of polyprenols on d-galactose-induced cognitive impairment in mice by testing on of behavioral and cognitive performance. In order to explore the possible role of polyprenols against d-galactose-induced oxidative damages, we assessed various biochemical indicators. Chronic administration of d-galactose (150 mg/kg·d, s.c.) for 7 weeks significantly impaired cognitive performance (both in step-through passive and active avoidance tests) and locomotor activity (in open-field test) and the ability of spatial learning and memory (in Morris water maze test) compared with the control group. The results revealed that polyprenols treatment for 2 weeks significantly ameliorated model mice’s cognitive performance and oxidative defense. All groups of polyprenols enhanced the learning and memory ability in step-through passive and active avoidance tests, locomotor activity in open-field test, and the ability of spatial learning and memory in Morris water maze test. Furthermore, high and middle level of polyprenols significantly increased total antioxidative capacity (T-AOC), glutathione peroxidase (GSH-Px), super oxide dismutase (SOD) activity, neprilysin (NEP), and β-site AβPP cleaving enzyme 1 (BACE1) expression, while nitric oxide (NO), nitric oxide synthase (NOS) activity, malondialdehyde (MDA) concentration, and the level of Aβ1-42 and presenilin 1 (PS1) were decreased. Polyprenols have a significant relieving effect on learning, memory, and spontaneous activities in a d-galactose-induced mouse model and ameliorates cognitive impairment and biochemical dysfunction in mice. In summary, we have demonstrated that polyprenols may ameliorate memory and cognitive impairment via enhancing oxidative defense and affecting generation and dissimilation of Aβ-related enzymes, suggesting that polyprenols represent a novel drug for treating Alzheimer’s disease.