SKP1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box

We have identified the yeast and human homologs of the SKP1 gene as a suppressor of cdc4 mutants and as a cyclin F-binding protein. Skp1p indirectly binds cyclin A/Cdk2 through Skp2p, and directly binds Skp2p, cyclin F, and Cdc4p through a novel structural motif called the F-box. SKP1 is required for ubiquitin-mediated proteolysis of Cin2p, Clb5p, and the Cdk inhibitor Sic1p, and provides a link between these molecules and the proteolysis machinery. A large number of proteins contain the F-box motif and are thereby implicated in the ubiquitin pathway. Different skp1 mutants arrest cells in either G1 or G2, suggesting a connection between regulation of proteolysis in different stages of the cycle.

Syndrome of hyperinfection with Strongyloides stercoralis

Two patients hyperinfected with Strongyloides stercoralis (an intestinal nematode) are described. Both were both in Puerto Rico and had left the island six to 15 years previously; both were receiving adrenal steroids (one for Hodgkin's disease and the other for Goodpasture's syndrome). One died shortly after diagnosis, but the other survived the hyperinfection syndrome and complicating bacterial sepsis and meningitis. In addition to our case reports, 103 previously described cases of presumed strongyloides hyperinfection are reviewed. Among 89 patients immunocompromised by therapy or disease, the mortality rate was 86%; bacterial sepsis often contributed to the fatal outcome. In most cases, infection was acquired in an endemic area, sometimes long before the hyperinfection syndrome occurred. The few patients who had never been to an endemic area had a history of prolonged contact with highly soiled material, an observation suggesting cross infection from a contaminated person. When administered in time, thiabendazole, the drug of choice for strongyloidiasis, was effective in 70% of cases. If intestinal infection with S. stercoralis is detected and treated before immunosuppressive therapy is initiated and if a high index of suspicion for the hyperinfection syndrome is maintained while immunosuppressive therapy is given, the mortality from this disease should decrease.

Calcium binding protein 1 of the protozoan parasite Entamoeba histolytica interacts with actin and is involved in cytoskeleton dynamics

Blocking expression of EhCaBP1, a calmodulin-like, four EF-hand protein from the protozoan parasite Entamoeba histolytica, resulted in inhibition of cellular proliferation. In this paper we report that EhCaBP1 is involved in dynamic changes of the actin cytoskeleton. Both endocytosis and phagocytosis were severely impaired in cells where EhCaBP1 expression was blocked by inducible expression of the antisense RNA. In wild-type cells both actin and EhCaBP1 were found to co-localize in phagocytic cups and in pseudopods. However, in antisense-blocked cells the phagocytic cup formation is affected. Analysis of the staining patterns in the presence and absence of actin dynamics inhibitors, jasplakinolide and cytochalasin D suggested that EhCaBP1 and polymerized F-actin co-localize on membrane protrusions. Direct interaction between soluble EhCaBP1 and F-actin was further demonstrated by a co-sedimentation assay. A variant of EhCaBP1 did not bind F-actin showing the specificity of the interaction between EhCaBP1 and actin. There is no significant change in the kinetics of in vitro polymerization of actin in presence of EhCaBP1, indicating that EhCaBP1 does not affect filament treadmilling. In addition, using atomic force microscopy; it was found that filaments of F-actin, polymerized in presence of EhCaBP1, were thinner. These results indicate that EhCaBP1 may be involved in dynamic membrane restructuring at the time of cell pseudopod formation, phagocytosis and endocytosis in a process mediated by direct binding of EhCaBP1 to actin, affecting the bundling of actin filaments.

Cooperative binding of Agrobacterium tumefaciens VirE2 protein to single-stranded DNA

The VirE2 protein of Agrobacterium tumefaciens Ti plasmid pTiA6 is a single-stranded-DNA-binding protein. Density gradient centrifugation studies showed that it exists as a tetramer in solution. Monomeric VirE2 active in DNA binding could also be obtained by using a different protein isolation procedure. VirE2 was found to be thermolabile; brief incubation at 37 degrees C abolished its DNA-binding activity. It was insensitive to the sulfhydryl-specific reagent N-ethylmaleimide. Removal of the carboxy-terminal 37 residues of the 533-residue VirE2 polypeptide led to complete loss of DNA-binding activity; however, chimeric fusion proteins containing up to 125 residues of the VirE2 C terminus were inactive in DNA binding. In nuclease protection studies, VirE2 protected single-stranded DNA against degradation by DNase I. Analysis of the DNA-VirE2 complex by electron microscopy demonstrated that VirE2 coats a single-stranded DNA molecule and that the binding of VirE2 to its substrate is cooperative.

A systematic review of the role of proton pump inhibitors for symptoms of laryngopharyngeal reflux

. Proton pump inhibitors are currently used widely for the treatment of laryngopharyngeal reflux. . This systematic review assessed the efficacy of proton pump inhibitors in the treatment of symptoms of laryngopharyngeal reflux. . Outcome measures used to assess efficacy of proton pump inhibitors included endoscopic laryngeal signs and pH recordings. .Only two small randomized-controlled trials included patients with objective evidence of reflux in the 24-h ambulatory oesophageal pH monitoring. . Pooled analysis of these two randomized-controlled trials failed to show any effect in favour of treatment with proton pump inhibitors. .Further randomized-controlled trials are required to ascertain the role of proton pump inhibitors in the treatment of laryngopharyngeal reflux.

Incidence and localization of sister chromatid exchanges induced by nickel and chromium compounds

Carcinogenic nickel compounds enhanced the incidence of sister chromatid exchanges (SCEs) in a concentration-dependent fashion in intact Chinese hamster ovary cells. There was a preferential induction of these exchanges in the heterochromatic regions of the chromosomes. CaCrO4 also caused a dose-dependent induction of SCEs. However, in contrast to NiCl2, the exchanges induced by CaCrO4 were not localized in any particular chromosomal region. The total incidence of exchanges was higher with CaCrO4 than with NiCl2. CaCrO4, crystalline NiS and NiCl2 enhanced the incidence of SCEs at concentrations below the threshold of DNA damage as detected by the technique of alkaline elution. Additionally, following treatment time intervals of 24-48 h, there was an increase in SCEs at concentrations of NiCl2 or CaCrO4 that produced little disruption of cell cycle progression. These results are consistent with the hypothesis that potently carcinogenic nickel compounds which are not very mutagenic exert selective effects on genetically inactive heterochromatin, while potently mutagenic and carcinogenic chromate do not appear to produce a similar predominance of SCEs in heterochromatic regions.

Immunoprophylaxis and immunotherapy against experimental visceral leishmaniasis

The ability of the Leishmanial parasite, UR6 (MHOM/IN/1978/UR6) to act as a immunoprophylactic and immunotherapeutic agent against experimental visceral leishmaniasis in a hamster model was tested. The Leishmanial parasite, UR6, lacked LPG but possessed abundant message for kinetoplastid membrane protein-11 (KMP-11), and failed to induce visceral infection when given through the intracardiac route, unlike the virulent Leishmania donovani, AG83 (MHOM/IN/1983/AG83), the causative agent of Kala-azar. Priming of macrophage with UR6 in vitro, induced superoxide (O2-) generation whereas a similar experiment with virulent AG83 inhibited O2- generation. This observation prompted us to test the efficacy of UR6 as a immunoprophylactic and immunotherapeutic agent. It was observed that priming of hamsters with either live or sonicated UR6 in the absence of any adjuvant provided strong protection against subsequent virulent challenge. The UR6 mediated protection was also observed in hamsters having established infection. Furthermore, UR6 primed infected hamsters displayed a greatly extended life span as compared to infected hamsters. To our knowledge, this is the first report concerning the use of an atypical Leishmanial parasite, UR6 in immunoprophylaxis and immunotherapy in the absence of any adjuvant.

Pathway of nickel uptake influences its interaction with heterochromatic DNA

Exposure of intact Chinese hamster ovary cells to water-soluble NiCl2 and to particulate crystalline NiS induced a concentration-dependent incidence of chromosomal aberrations which included gaps, breaks, and exchanges. Exposure of cells to crystalline NiS particles caused a high incidence of chromatid exchanges and dicentrics and produced what appears to be an effect on the condensation state of the heterochromatic long arm of the X chromosome. Treatment of cells with NiCl2 did not cause any significant effect on the long arm of the X chromosome, and there was a much lower incidence of the dicentric type of chromosomal aberrations compared to NiS. To examine whether the fragmentation/decondensation of the long arm of the X chromosome produced by crystalline NiS particles was due to a phagocytic pathway of uptake of NiS particles, cells were treated with NiCl2-albumin complexes that had been encapsulated in liposomes. Although treatment of cells with NiCl2-albumin complexes yielded higher intracellular nickel levels than were obtained by treatment of cells with NiCl2, at comparable intracellular levels fragmentation/decondensation of the heterochromatic long arm of the X chromosome was observed when nickel (II) was delivered by way of a liposome but not when cells were treated with unencapsulated NiCl2. Ionic nickel alone irrespective of its delivery mechanism exhibited some preference for heterochromatin, since there was a higher incidence of aberrations observed in the heterochromatic centromeric region of chromosomes. These observations suggest that the pathway of delivery of Ni2+ from NiS particles may be responsible for a preferential interaction of this metal with heterochromatin leading to an effect on the condensation state/fragmentation of the heterochromatic long arm of the X chromosome.

Recovering maxillofacial trauma patients: the hidden problems

This longitudinal study highlights the psychological and functional problems that can result from maxillofacial trauma. This is the first study to report outcome at one year. A total of 147 patients admitted for surgery following facial trauma were recruited over a seven-month period. Three questionnaires were used to record patient-derived levels of dysfunction: the Hospital Anxiety Depression scale, a modified University of Washington Quality of Life questionnaire and five non-validated facial trauma items. At one year 46 patients (31%) responded. Although there were significant improvements in scores from pre-operatively to one year, with all patients being discharged from outpatient follow-up, there was a substantial level of subjective symptomatology. Most notable was the level of anxiety and depression, which were present in 30% of the sample at both time points. Health-care professionals tend to underestimate the long-term effects of maxillofacial trauma. To improve patient care, greater appreciation of these problems is required at the time of initial management.

Tumour-like presentations of anogenital herpes simplex in HIV-positive patients

Genital and perianal ulcers seen in patients with HIV are commonly due to herpes simplex virus (HSV) infection. While it is well known that the characteristic presentation of HSV is a vesicular rash or crops of erosions, the clinical presentation of genital HSV infection in HIV is varied and can assume vegetative, hypertrophic, condyloma-like, nodular, ulcerative and tumour-like nodules or plaques. These unusual presentations often lead to a delayed diagnosis. We describe five immunocompromised HIV-positive patients with CD4 counts ranging from 114 to 326 cells/μL with unusual presentations of anogenital herpes.

Selective impairment of protein kinase C isotypes in murine macrophage by Leishmania donovani

Leishmania donovani, an obligate intracellular parasite resides and multiplies within macrophage of the reticuloendothelial system. The intracellular signalling mechanism involved in the impaired oxidative response in leishmaniasis has not yet been clearly established. Generation of superoxide anion (O2-) is supposed to be the first line of host defence during microbial invasion. We found a substantial inhibition of superoxide anion generation in parasitized macrophages, which was just the reverse in case of macrophages challenged with Lipophosphoglycan (LPG) deficient attenuated leishmanial parasite UR-6. The generation of O2- essentially needs the prior activation of protein kinase C (PKC) mediated phosphorylation events. Our study proposed that phosphorylation of 67, 54, 47 and 36 kDa proteins was attenuated during infection. This was supported by PKC activity study, where Ca-dependent PKC activity was inhibited but, Ca-independent PKC activity was enhanced. This result was further confirmed by using isotype specific pseudosubstrate inhibitors of Ca-dependent PKC beta and Ca-independent PKC zeta. Application of beta-pseudosubstrate could not alter the Ca-dependent PKC activity but zeta-pseudosubstrate inhibited the Ca-independent PKC activity in infected macrophages. Our immunoblot analysis with specific antibody against PKC beta and PKC zeta isotypes showed down regulation of PKC beta-II expression with concomitant induction of PKC zeta. Such inhibition of Ca-dependent PKC beta was reversed in macrophages treated with UR-6. Taken together, our observations revealed that infection with L. donovani selectively attenuates both the expression and activity of Ca-dependent PKC beta.

Mutation spectrum in BBS genes guided by homozygosity mapping in an Indian cohort

Bardet-Biedl syndrome (BBS), a ciliopathy disorder with pleiotropic effect manifests primarily as retinal degeneration along with renal insufficiency, polydactyly and obesity. In this study, we have performed homozygosity mapping using NspI 250K affymetrix gene chip followed by mutation screening of the candidate genes located in the homozygous blocks. These regions are prioritized based on the block length and candidature of the genes in BBS and other ciliopathies. Gene alterations in known BBS (22) and other ciliopathy genes such as ALMS1 (2) were seen in 24 of 30 families (80%). Mutations in BBS3 gene, inclusive of a novel recurrent mutation (p.I91T) accounted for 18% of the identified variations. Disease associated polymorphisms p.S70N (BBS2), rs1545 and rs1547 (BBS6) were also observed. This is the first study in Indian BBS patients and homozygosity mapping has proved to be an effective tool in prioritizing the candidate genes in consanguineous pedigrees. The study reveals a different mutation profile in the ciliopathy genes in Indian population and implication of novel loci/genes in 20% of the study group.

Assessment of cardiac function in patients with the acquired immunodeficiency syndrome

We have assessed right and left ventricular function by multigated radionuclide ventriculography in 12 consecutive patients with acquired immunodeficiency syndrome (AIDS) grouped according to the CDC classification system for HIV infection. Results were correlated with clinical, electrocardiographic and echocardiographic findings. Clinical examination and chest x-ray films showed no evidence of acute cardiac or pulmonary pathology. Five patients had evidence of ventricular dysfunction by radionuclide ventriculography along with significant ECG abnormalities. Three patients had abnormal ECG findings with normal ejection fractions. Echocardiography showed no evidence of significant valvulopathy or pericardial disease except for one patient with fibrinous strands associated with the pericardium. Decreased ejection fractions did not correlate with disease classification, risk group or survival. This study suggests that a major percentage of AIDS patients have some evidence of cardiac abnormalities. We conclude that abnormal ECG findings in an AIDS patient should alert the clinician to possible underlying ventricular dysfunction.

Effect of glycoPEGylation on factor VIIa binding and internalization

SUMMARY

Recombinant coagulation factor VIIa (rFVIIa), which is widely used for treatment of bleeding episodes in haemophilia patients with inhibitors, is cleared from the circulation relatively fast with a plasma half-life of 2-4 h. PEGylation is an established and clinically proven strategy for prolonging the circulatory life-time of bio-therapeutic proteins. The aim of this study was to investigate the effect of glycoPEGylation of rFVIIa on rFVIIa binding to its cellular receptors and its subsequent internalization. rFVIIa and glycoPEGylated rFVIIa were labeled with (125)I and the radio-iodinated proteins were used to monitor rFVIIa binding and uptake in endothelial cells and fibroblasts. FVIIa-TF activity at the cell surface was analyzed by a factor X activation assay. Modification of rFVIIa with PEG impaired rFVIIa binding to both endothelial cell protein C receptor and tissue factor (TF) on cell surfaces. The internalization of PEGylated rFVIIa in endothelial cells and fibroblasts was markedly lower compared to the internalization of rFVIIa in these cells. PEGylated rFVIIa was able to activate factor X on TF expressing cell surfaces at a rate similar to that of unmodified rFVIIa when the cells were not subjected to multiple washings to remove the free ligand. General effects such as steric hindrance or changes in electrostatic binding properties of the modified rFVIIa to its receptors are probably responsible for this impairment rather than a loss of specific recognition of the receptors, which could explain near normal activation of factor X by glycoPEGylated rFVIIa on TF expressing cells while its uptake is reduced.

The amygdaloid complex, corticotropin releasing factor and stress-induced gastric ulcerogenesis in rats

The amygdaloid complex and corticotropin releasing factor (CRF) are both important in stress reactions and we thus evaluated the effects of intra-amygdalar CRF on stress ulceration in rats. Bilateral micro-applications of CRF (0.05, 0.5 or 5.0 micrograms) into the central amygdala (CEA) attenuated cold restraint-induced gastric mucosal lesions in a dose-related manner. Similar gastric cytoprotective effects were seen with intra-CEA noradrenaline (NA; 3.0 micrograms), whereas the NA neurotoxin, DSP-4 (25 micrograms), or the beta-adrenoceptor antagonist, propranolol (1 microgram), aggravated stress ulcer pathology. Intra-CEA pretreatment with DSP-4 or propranolol clearly reversed the ulceroprotective effects of CRF during stress. These results indicate that the CEA is a neural substrate for CRF effects, and CRF-NA interactions in this limbic area are crucial for the regulation of stress ulcerogenesis.

Endoscopic stapling of pharyngeal pouch

The relatively new technique of endoscopic stapling in the surgical management of pharyngeal pouch has gained widespread popularity over the last few years. The technique seems to be the procedure of choice as it is easier and quicker to perform and has a lower morbidity compared with open techniques. We present here an overview of the current evidence provided by a literature search performed by Ovid MEDLINE on literature published between January 1993 and May 2003 on endoscopic stapling of pharyngeal pouch. Several case series have been reported on various aspects of the surgery. The modifications in technique, peri-operative care, success rate, complications and recurrence are summarized, based on observational analytical case series. There were no randomized controlled trials comparing this approach to any other endoscopic or open surgical techniques for pharyngeal pouch.