When and how to eradicate Helicobacter pylori: role of histamine receptor antagonists

Peptic ulcer is today frequently considered to be an infectious disease. The bacteria assumed to be the cause of gastric or duodenal ulcer was first called Campylobacter pyloridis and later C. pylori because of its structural similarity to other Campylobacter species. Later, unique characteristics were reported, and it was renamed Helicobacter pylori (Hp). In retrospect, it was presumably first described in man in 1938 (Doenges 1938), although the clinical significance was not established until 1983 (Warren 1983, Warren and Marshall 1983). It is a spiral-shaped, gram-negative bacteria with four to six flagella and dimensions of 0.5 x 3.0 micron. . With the help of these flagella, it moves into the mucous layer overlying the gastric epithelium where it colonizes at the interface of the mucous layer and the surface epithelial cells. It can be found in any part of the gastrointestinal tract demonstrating gastric epithelium, i.e. the stomach and metaplastic areas of the esophagus or the duodenum. One characteristic of this bacteria is the production of a urease enzyme that catalyzes urea to ammonium and bicarbonate. The production of ammonium causes the development of an alkaline microenvironment that protects it from the gastric acid. In the presence of urea, the organism will therefore replicate to a pH as low as 4.3 and survive without replication to a pH as low as 2.3. In Western countries, an increase in the prevalence of Hp infection is observed in the population with progressing age. In childhood, infection before the age of 20 years is rare. At the age of 60 years or older, however, the prevalence rate is on the order of 40% to 60% (Dooley et al. 1989, Perez-Perez et al. 1988, Marshall 1994). The seroconversion rate in adults is lower than 1% per year (Parsonnet et al. 1992). The infection seems to be stable, probably persisting for many years or even a lifetime.

Association of a M(r) 90,000 phosphoprotein with protein kinase PKR in cells exhibiting enhanced phosphorylation of translation initiation factor eIF-2 alpha and premature shutoff of protein synthesis after infection with gamma 134.5- mutants of herpes simplex virus 1

The protein encoded by the gamma 134.5 gene of herpes simplex virus precludes premature shutoff of protein synthesis in human cells triggered by stress associated with onset of viral DNA synthesis. The carboxyl terminus of the protein is essential for this function. This report indicates that the shutoff of protein synthesis is not due to mRNA degration because mRNA from wild-type or gamma 134.5- virus-infected cells directs protein synthesis. Analyses of the posttranslational modifications of translation initiation factor eIF-2 showed the following: (i) eIF-2 alpha was selectively phosphorylated by a kinase present in ribosome-enriched fraction of cells infected with gamma 134.5- virus. (ii) Endogenous eIF-2 alpha was totally phosphorylated in cells infected with gamma 134.5- virus or a virus lacking the 3' coding domain of the gamma 134.5 gene but was not phosphorylated in mock-infected or wild-type virus-infected cells. (iii) Immune precipitates of the PKR kinase that is responsible for regulation of protein synthesis of some cells by phosphorylation of eIF-2 alpha yielded several phosphorylated polypeptides. Of particular significance were two observations. First, phosphorylation of PKR kinase was elevated in all infected cells relative to the levels in mock-infected cells. Second, the precipitates from lysates of cells infected with gamma 134.5- virus or a virus lacking the 3' coding domain of the gamma 134.5 gene contained an additional labeled phosphoprotein of M(r) 90,000 (p90). This phosphoprotein was present in only trace amounts in the immunoprecipitate from cells infected with wild-type virus or mutants lacking a portion of the 5' domain of gamma 134.5. We conclude that in the absence of gamma 134.5 protein, PKR kinase complexes with the p90 phosphoprotein and shuts off protein synthesis by phosphorylation of the alpha subunit of translation initiation factor eIF-2.

Capillary electrophoresis for screening of adenylosuccinate lyase deficiency

We report a new screening method for adenylosuccinate lyase (ASase) deficiency using capillary electrophoresis (CE). This enzyme defect causes secondary autism and psychomotor retardation in early childhood. In all body fluids of these patients, two succinylpurine metabolites can be found that are normally not detectable: succinyladenosine and succinylaminoimidazole carboxamide (SAICA) riboside. A Beckman P/ACE 2050 capillary electrophoresis system was used with a 47.1 cm capillary, 75 microns ID, and the P/ACE Beckman UV absorbance detector. Untreated urine, injected for 1 s, was separated in a pH 8.63 borate buffer at 20 kV. The two succinylpurines (migration times 13.36 and 13.60 min) were detected at 254 nm only in urine of patients with ASase deficiency but not in control samples.

Evaluation of the protective efficacy of reshaped human monoclonal antibody RSHZ19 against respiratory syncytial virus in cotton rats

Reshaped human MAb RSHZ19, which is specific for the surface fusion protein of respiratory syncytial virus (RSV) is in clinical development for the prevention and treatment of RSV-induced disease in human infants. The current studies profile lung virus clearance and evaluate lung histopathology in MAb-treated, RSV-infected cotton rats, a well characterized model of RSV infection. The highest dose of this MAb (10 mg/kg) administered parenterally 24 h before infection decreased subgroup A or B RSV lung titers to below detectable levels (> or = 2.3 log10 reduction), and significantly reduced lung virus titers (> or = 2.0 log10 reduction) when administered 96 h postinfection. Prophylactic administration of 10 mg/kg RSHZ19 was significantly more protective than 1000 mg/kg conventional human immune serum globulin (HSIg), and protective serum-neutralizing titers in MAb-treated animals (1:32, which correlated with approximately 40 micrograms/ml determined by anti-idiotype ELISA) were significantly lower than those reported previously for HSIg or for convalescent human serum (1:200-1:400). MAb concentration in lung lavages was determined by ELISA to be approximately 1% of the serum MAb concentration, but was not detectable by neutralization assay. The degree of lung histopathology in MAb-treated cotton rats was proportional to lung virus titer, and inversely proportional to the RSHZ19 dose administered. There was no evidence of exacerbated disease in the lungs of MAb-treated animals. These studies thus support the potential clinical utility of RSHZ19 MAb in the prevention and treatment of RSV-induced disease in humans.

Critical steps in total knee arthroplasty. A method of analyzing operative procedures

We have analyzed the operation of knee arthroplasty using the Whiteside Mark II prosthesis, and found that it could be broken down into 42 steps, some of which are more important than others and can be considered as critical. We have identified 4 criteria to evaluate a critical step: 1) it must be necessary to complete the procedure, 2) it must take a significantly longer time to perform than other steps, 3) it must be revised significantly more frequently than other steps and 4) it must take significantly longer to revise than other steps. Two steps have been found to which all 4 criteria applied, namely placement of the femoral cutting jig and the first femoral saw cuts.

Some basic biomechanical characteristics of medullary pressure generation during reaming of the femur

We measured femoral intramedullary pressures and applied axial thrust force generated in vitro during reaming with the AO and Zimmer systems. Six pairs of cadaver femora were instrumented with pressure taps midshaft and in the distal diaphysis, a load cell distally to measure force, and a displacement transducer to monitor reamer position. Following initial hand reaming, intramedullary power reaming was conducted utilizing a 9-mm reamer initially, with subsequent increases in steps of 0.5 mm. All femora were maintained at 37 degrees C and albumin was used to maintain a fluid-filled canal. The highest pressures consistently occurred during initial power reaming, with peak pressures ranging from 270 to 1500 mmHg amongst femora with the AO system. No significant differences were found in the peak pressures generated for the two systems (P = 0.10). The pressure measurements at the two locations in the femur were consistently similar, indicating that pressures are continuous throughout this aspect of the femur. The pressures were not correlated with instantaneous applied axial thrust (R2 = 0.191), and this could be attributed chiefly to the additional friction force of cutting. While pressure generation in the medullary canal upon reaming is likely governed by the rate of clearance of canal content, this is a highly variable response produced by characteristics of the femur which are still not fully understood.

Multiple-state equilibrium unfolding of guanidino kinases

The denaturant-induced equilibrium unfolding of octameric mitochondrial creatine kinase, dimeric cytosolic muscle-type creatine kinase, and monomeric arginine kinase was investigated. Stable unfolding intermediates for all three enzymes were manifested by a strongly biphasic red shift of intrinsic protein fluorescence upon increasing denaturant concentrations. In the intermediate state, all proteins were monomeric and enzymatically inactive, but still retained a globular shape. Native tertiary structure interactions were largely disrupted, while at least 50% of the secondary structures were conserved, as suggested by near- and far-UV circular dichroism, respectively. A significantly increased surface hydrophobicity of the intermediate conformation, compared to both the native and the fully unfolded states, was observed by the binding of the hydrophobic fluorescent dye ANS. The observed properties agree formally with the definition of the molten globule state, but can be alternatively explained by a sequential unfolding of individual domains, involving a transient exposure of domain interfaces. Very similar unfolding profiles for all three proteins suggest that the formation of stable unfolding intermediates is not a consequence of the specific oligomeric structures of the CKs but rather due to a common, probably two-domain architecture of the guanidino kinase protomers.

Dimer-dimer interactions in octameric mitochondrial creatine kinase

Mitochondrial creatine kinase (Mi-CK) forms octamers and dimers, which are readily interconvertible in vitro. The kinetic and thermodynamic octamer stability of wild-type and two mutant, octamer-destabilized forms of chicken sarcomeric Mi-CK was investigated at varying temperatures, pHs, and salt and substrate concentrations, in order to identify parameters which might regulate the octamer/dimer ratio in vivo and to assess the nature of octamer-stabilizing interactions. For wild-type Mi-CK, the rate of the transition state analogue complex (TSAC)-induced octamer decay increased with increasing temperature up to 28 degrees C; increasing pH markedly accelerated the decay in a biphasic manner. The substrate-dependent decay data suggest that also the productive enzymatic transition state of Mi-CK induces an octamer-destabilizing conformation. Thermodynamically, the octamers are stabilized by a combination of hydrophobic and polar contributions. Van't Hoff analysis showed that hydrophobic interactions dominate both in the absence of substrates and in the TSAC conformation, since the equilibrium octamer fractions increased with increasing temperatures, in spite of the accelerated decay kinetics. For the Mi-CK mutant E4Q, a similar temperature dependence was found; in contrast, mutant W264C exhibited an inverted temperature dependence, suggesting that hydrophobic interactions might be largely abolished in this mutant. Both the kinetic and the thermodynamic data seem to suggest that the octamer-dimer transitions of Mi-CK might not play a major role in a fast regulation of mitochondrial energy metabolism, but could rather be involved in slow long-term modulations.

[Comparative evaluation of the voice prosthesis after laryngectomy]

Voice quality was assessed in 44 laryngectomized patients using 13 subjective and 8 objective criteria. All patients were using either esophageal voice. Servox vibrator or a voice prosthesis. Five of eight patients with voice prostheses had secondary tracheo-esophageal punctures. Subjective assessment showed better results for most of the criteria in favor of the voice prosthesis. With objective measurements, maximum phonation times and maximum numbers of syllables per intake of air were significantly higher in patients with voice prostheses compared with other techniques for voices restoration. Overall intelligibility in the postlaryngectomy "telephone test" was obviously better in the patients using the prostheses than in those with esophageal voice or Servox vibrator voice, while no significant differences were found among prostheses and esophageal voices in the medium speed of speaking, various sound pressure levels and medium habitual pitch range. In patients with primary voice prostheses maximum phonation time was longer (average, 2.5 s) than in patients with secondary voice prostheses. Overall intelligibility of the different groups was not significantly influenced by age. The need for postoperative voice rehabilitation was significantly higher in patients with esophageal voices compared with those using Servox vibrator voice or a voice prostheses. Our results support in principle primary tracheo-esophageal puncture for a voice prostheses as best treatment of the laryngectomized patient.

Purification and characterization of an extracellular levansucrase from Pseudomonas syringae pv. phaseolicola

Levansucrase (EC 2.4.1.10), an exoenzyme of Pseudomonas syringae pv. phaseolicola, was purified to homogeneity from the cell supernatant by chromatography on TMAE-Fraktogel and butyl-Fraktogel. The enzyme has molecular masses of 45 kDa under denaturing conditions and 68 kDa during gel filtration of the native form. In isoelectric focusing, active bands appeared at pH 3.55 and 3.6. Maximum sucrose cleaving activities were measured at pH 5.8 to 6.6 and 60 degrees C. The enzyme was highly tolerant to denaturing agents, proteases, and repeated freezing and thawing. The molecular weight of the produced levan depended on temperature, salinity, and sucrose concentration. The enzyme had levan-degrading activity and did not accept raffinose as a substrate. Comparison of the N-terminal amino acid sequence with the predicted amino acid sequence of levansucrases from Erwinia amylovora and Zymomonas mobilis showed 88 and 69% similarity, respectively, in amino acids 5 to 20. No similarity could be detected to levansucrases of gram-positive bacteria in the first 20 amino acids. By comparison of all levansucrases which have been sequenced to date, the enzyme seems to be conserved in the gram-negative bacteria. The rheological behavior of the product levan prompted a new assessment of the enzyme's role in pathogenesis. Depending on formation conditions, levan solutions exclude other polymer solutions. This behavior supports the presumption that the levansucrase is important in the early phase of infection by creating a separating layer between bacteria and plant cell wall to prevent the pathogen from recognition.

Differential selenium-dependent expression of type I 5'-deiodinase and glutathione peroxidase in the porcine epithelial kidney cell line LLC-PK1

The Se-dependent expression of two selenoproteins, cytosolic glutathione peroxidase (cGPx) and type I iodothyronine-5'-deiodinase (5'DI), was investigated in the porcine epithelial kidney cell line LLC-PK1 in serum-free medium. The selenite-dependent expression of cGPx and 5'DI was revealed by enzyme-activity measurements, affinity labelling of 5'DI, metabolic labelling of proteins with 75Se and steady-state mRNA analysis. The expression of the two enzymes strongly depended on selenite concentrations of the culture medium. cGPx required 2-fold higher selenite levels than 5'DI to reach half-maximal activity. The Se-dependent enzyme activities were approximately paralleled by the corresponding steady-state mRNA levels. The response of the two enzymes to Se supply was further characterized by kinetic Se-depletion and -repletion experiments. Upon removal of medium selenite, cGPx activity decreased exponentially, whereas after an initial decrease over 1-2 days, 5'DI levels completely recovered during a further 2 days. These data indicate a differential Se-dependent regulation of the two selenoproteins, with 5'DI being preferentially supplied with the trace element Se, thus ensuring a continuous cellular capacity for thyroid-hormone activation, even under Se-deficient conditions. The abundant cGPx in cells with sufficient Se supply might serve as a cellular Se store which can be mobilized for the synthesis of more vital selenoproteins such as 5'DI under shortage conditions. Thus, a cellular hierarchy of selenoprotein expression, reflected by different individual regulation mechanisms at the transcriptional and post-transcriptional level, adds to the previously recognized tissue-specific hierarchy of Se retention.

An investigation on heat transfer to the implant-bone interface due to abutment preparation with high-speed cutting instruments

Excessive heat generation at the implant-bone interface may cause irreversible bone damage and loss of osseointegration. The effect of heat generation in vitro at the implant surface caused by abutment reduction with medium- and extra-fine-grain diamond and tungsten burs in a high-speed dental turbine was examined. Titanium-alloy abutments connected to a titanium-alloy cylindrical implant embedded in an acrylic-resin mandible in a 37 degrees C water bath were reduced horizontally and vertically. Temperature changes were recorded via embedded thermocouples at the cervix and apex of the implant surface. Analysis of variance for repeated measures was used to compare seven treatment groups. Thirty seconds of continuous cutting with standard turbine coolant caused a mean temperature increase of 1 degrees C with a maximum of 2 degrees C. Similar tungsten cutting caused a mean increase of 2 degrees C with a maximum of 4.7 degrees C, significantly higher than diamond reduction. Additional air-water spray for continuous tungsten cutting had no significant effect, while intermittent cutting for 15-second increments reduced the temperature increase by 75%. Thus, abutment reduction with medium-grit diamonds using intermittent pressure and normal turbine coolant is unlikely to cause an interface-temperature increase sufficient to cause irreversible bone damage and compromise osseointegration.

Occlusion and stability of synthetic femoral canal plugs used in cemented hip arthroplasty

The occlusion and stability of five synthetic plugs used to restrict the femoral canal prior to cemented arthroplasty was assessed. A model was employed consisting of a hollow wooden dowel to simulate the canal, with adapters fixed to both ends to accommodate cement insertion and pressurization, and to produce a closed distal cavity. Three different canal diameters within the range accommodated by the plug selected were employed to assess insertion force, distal pressure during both insertion and pressurization of acrylic cement, and plug migration and leakage for each device. There was a wide variation among plugs in the magnitudes of the force and distal pressure upon plug insertion. During cement pressurization, cement leakage and/or plug migration was noted in all trials, and either of these events resulted in pressure rises in the distal cavity. Most notably, differences of only 0.5 mm in the diameter of the canal resulted in marked changes in the occlusion and stability achieved. It is concluded that for the range of canal sizes anticipated intraoperatively, these synthetic plugs appear deficient to varying extents in their ability to occlude or remain stable in the intramedullary canal.

Effect of carotenoids on in vitro immunoglobulin production by human peripheral blood mononuclear cells: astaxanthin, a carotenoid without vitamin A activity, enhances in vitro immunoglobulin production in response to a T-dependent stimulant and antigen

The effect of carotenoids on in vitro immunoglobulin (Ig) production by peripheral blood mononuclear cells (PBMNC) was examined by employing blood samples from adult volunteers and full-term newborn babies (umbilical cord blood). Under carotenoid-supplemented culture conditions, cells were stimulated by polyclonal stimulants, neoantigens, and a recall antigen (Ag), and IgM, IgA, and IgG levels in the culture supernatant were measured. Beta-carotene and astaxanthin were used as representatives of carotenoids with and without vitamin A activity, respectively. Astaxanthin enhanced IgM production in response to T-dependent Ag (TD-Ag) and a T-dependent polyclonal stimulant. Astaxanthin also augmented IgG production in response to a recall Ag. IgA production without supplemental carotenoids was negligible for all stimuli. However, in carotenoid-supplemented cultures, IgA production was significantly higher in response to a T-dependent polyclonal stimulant than in unsupplemented cultures. IgM and IgA production was augmented at 10(-8) mol/l astaxanthin, whereas astaxanthin enhanced IgG production in response to a recall Ag at 10(-10)-10(-9) mol/l. Similar enhancing actions of astaxanthin on IgM production were observed in cord blood mononuclear cells (CBMNC), although CBMNC produced less IgM than adult PBMNC. Beta-carotene did not have a significant effect on human Ig production. The carotenoid actions were not demonstrated under serum-free culture conditions; serum is essential for solubilization of carotenoids. In summary, this study has shown for the first time that astaxanthin, a carotenoid without vitamin A activity, enhances human Ig production in response to T-dependent stimuli.

Disturbed lower denture stability due to lipoma in the floor of the mouth

An unusual case of lipoma arising in the floor of the mouth of a 70-year-old man is presented. The unusual appearance suggests that the tumour be included as a rare possibility in the differential diagnosis of swellings in the floor of the mouth that can also adversely affect lower denture stability.

Identification of functional domains in AMPD1 by mutational analysis

AMP deaminase (AMPD) is a complex allosteric enzyme encoded by a multigene family in higher eukaryotes. The amino terminus of each AMPD gene is unique, while the mild and carboxy termini have been highly conserved among all the AMPD genes. Mutational analyses of the AMPD1 gene demonstrate that the catalytic site and a regulatory site, likely an ATP binding site, are located in the highly conserved carboxy terminus. Deletion mutants and a normal splice variant of AMPD1 demonstrate that the amino terminus has a profound influence on catalytic activity of AMPD and by inference from prior studies this region also influences binding of AMPD1 to myosin. Results of these studies suggest a regulatory model in which alternative splicing in the amino terminal region of AMPD1 generates isoforms of AMPD that exhibit differential sensitivity to effector molecules such as ATP.