Effect of long-term calcitonin administration on steroid-induced osteoporosis after cardiac transplantation.

BACKGROUND: Early, rapid bone loss and fractures after cardiac transplantation are well-documented complications of steroid administration; therefore, we undertook this study on the effects of long-term calcitonin on steroid-induced osteoporosis. METHODS: Twenty-three heart transplant recipients on maintenance immunosuppression with cyclosporine, mycophenolate mofetil and prednisone were retrospectively studied. All patients received long-term prophylactic treatment with elemental calcium and vitamin D. Twelve (52.2%) patients also received long-term intranasal salmon calcitonin, whereas 11 (47.8%) received none. Bone mineral density and vertebral fractures were assessed at yearly intervals. Statistical comparisons between each group's bone loss during the first year and in the early (1 to 3 years), intermediate (4 to 6 years) and late (7+ years) post-transplantation periods were done. RESULTS: Lumbar spine bone loss was significant during the early follow-up period in the group not receiving calcitonin (0.744 +/- 0.114 g/cm(2) vs 0.978 +/- 0.094 g/cm(2) [p = 0.002]). The calcitonin group showed bone mineral density (BMD) levels within normal average values throughout the study period. BMD increased in the no-calcitonin group during the intermediate (4 to 6 years) and late (7+ years) follow-up periods, with values approaching normal average and no significant difference between the 2 groups (0.988 +/- 0.184 g/cm(2) vs 0.982 +/- 0.088 g/cm(2) [p = 0.944] and 0.89 +/- 0.09 g/cm(2) vs 1.048 +/- 0.239 g/cm(2) [p = 0.474], respectively). CONCLUSIONS: Prophylactic treatment with intranasal salmon calcitonin prevents rapid bone loss associated with high-dose steroids early after cardiac transplantation. Long-term administration does not seem warranted in re-establishing BMD.     

Regulation of the small GTPase RhoA by syndecan-4 and integrins in focal adhesion formation

Introduction The transmembrane heparan sulfate proteoglycan, syndecan‐4, and integrins are important receptors for focal adhesion (FA) formation on fibronectin (FN) substrates. The small GTPase RhoA is also known to regulate FA and stress fiber formation. It has been suggested that syndecan‐4 and integrins co‐operatively regulate the assembly of FA in a Rho‐dependent manner, but the mechanism is unclear. Here, we examined the function of RhoA and the Rho effector kinases ROCKs in syndecan‐4 signalling on the process of FA formation and the possible mechanism by which syndecan‐4 may regulate RhoA activity. Methods Primary rat embryonic fibroblasts (REFs) were seeded on FN or ‘RGD’‐containing integrin‐binding domain of FN and lysed at various time points. The amount of active form of RhoA in each lysate was analysed by pull‐down experiments. Results and discussion The relative activities of RhoA showed one peak in the process of FA formation on FN, whereas no peak was obtained on the integrin‐binding domain. The one peak of RhoA activity on integrin‐binding domain was restored by addition of heparin‐binding domain into medium. These results suggested that a signal through syndecan‐4 link to the Rho pathway. Both ROCK‐I and ‐II isozymes were present in REF cell lysates and each could be specifically immunoprecipitated. The ROCK kinase activities in immunoprecipitates were analysed using GST‐myosin light chain as a substrate. The amount of ROCK‐I and ‐II activities changed through the adhesion process on FN and appeared to be independently regulated. Therefore, one or both ROCKs may be downstream of a syndecan‐4‐mediated signalling response through RhoA. The core protein of syndecan‐4 can directly bind to and activate PKC‐α. We found that PKC‐α could phosphorylate Rho‐Guanine Nucleotide Dissociation Inhibitor (GDI) in vitro. It has been suggested that PKC‐α‐mediated phosphorylation of Rho GDI stimulates GDI dissociation, thereby resulting in Rho activation. It is possible that syndecan‐4 regulates Rho/ROCK pathway through PKC‐α activation on the process of FA formation.     

Nosocomial spread of an unusual methicillin-resistant Staphylococcus aureus clone that is sensitive to all non-beta-lactam antibiotics, including tobramycin

Between January and December 1999, in Hippokration General Hospital, Thessaloniki, Greece, a large proportion of the methicillin-resistant Staphylococcus aureus isolates (34.4%) exhibited susceptibility to virtually all alternative non-beta-lactam antibiotics, including tobramycin. Twenty-five of them were selected randomly for further testing; all belonged to a unique genotype and were characterized as heterogeneously resistant to oxacillin. The aadD gene, encoding tobramycin resistance, failed to be amplified in all cases, indicating absence of the gene or the entire plasmid pUB110 from the mec DNA.     

Detection of extended-spectrum beta-lactamases in clinical isolates of Enterobacter cloacae and Enterobacter aerogenes

The aim of the present study was to investigate the frequency of extended-spectrum beta-lactamases (ESBLs) in a consecutive collection of clinical isolates of Enterobacter spp. The abilities of various screening methods to detect ESBLs in enterobacters were simultaneously tested. Among the 68 consecutive isolates (56 Enterobacter cloacae and 12 Enterobacter aerogenes isolates) that were analyzed for beta-lactamase content, 21 (25 and 58%, respectively) possessed transferable ESBLs with pIs of 8.2 and phenotypic characteristics of SHV-type enzymes, 8 (14.3%) of the E. cloacae isolates produced a previously nondescribed, clavulanate-susceptible ESBL that exhibited a pI of 6.9 and that conferred a ceftazidime resistance phenotype on Escherichia coli transconjugants, and 2 E. cloacae isolates produced both of these enzymes. Among the total of 31 isolates that were considered ESBL producers, the Vitek ESBL detection test was positive for 2 (6.5%) strains, and the conventional double-disk synergy test (DDST) with amoxicillin-clavulanate and with expanded-spectrum cephalosporins and aztreonam was positive for 5 (16%) strains. Modifications of the DDST consisting of closer application of the disks (at 20 instead of 30 mm), the use of cefepime, and the use of both modifications increased the sensitivity of this test to 71, 61, and 90%, respectively. Of the 37 isolates for which isoelectric focusing failed to determine ESBLs, the Vitek test was false positive for 1 isolate and the various forms of DDSTs were false-positive for 3 isolates.     

Diversity of aminoglycoside resistance inEnterobacter cloacae in Greece

NinetyEnterobacter cloacae strains isolated from 12 Greek hospitals were examined in terms of epidemiological types and resistance mechanisms. Using O serotyping 69 % of the strains were assigned to a specific serotype and overall 16 different serotypes were identified. The combination of serotyping, phagetyping and biotyping efficiently discriminated most of the strains, indicating that single epidemic strains were not prevalent, although serotypes 3, 7, and group II predominated. Eight representative strains, all resistant to gentamicin, tobramycin, amikacin and netilmicin, were further examined for transferability and mechanisms of resistance. Aminoglycoside resistance was found to be transferable in most strains, and 13 R plasmids of 40–120 MDa molecular weight were detected. The enzymes detected consisted of three enzymes active against gentamicin [ANT(2), AAC(3)-I and AAC(3)-V]; three active against tobramycin [ANT(2), AAC(3)-V and AAC(6)-I]; two active against netilmicin [AAC(3)-V and AAC(6)-I]; and one active against amikacin [AAC(6)-I]. APH(3) and ANT (3), which modify neomycin and streptomycin plus spectinomycin respectively, were also found. Overall up to five aminoglycoside modifying enzymes were detected on the same R plasmid, AAC(6)-I plus ANT(2) being the most prevalent. The high incidence of multiresistance inEnterobacter cloacae and the fact that resistance is due to enzymatic inactivation of the antibiotics, indicate that in Greece this species might act as a gene pool for the spread of resistance to other bacteria of clinical relevance.     

European seroepidemiology network 2: Standardisation of assays for seroepidemiology of varicella zoster virus.

BACKGROUND: The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe. OBJECTIVE: To allow comparison of antibody prevalence in different countries by standardising results into common units. STUDY DESIGN: For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel. RESULTS: Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage. CONCLUSION: This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.     

Pseudo-outbreak of imipenem-resistant Acinetobacter baumannii resulting from false susceptibility testing by a rapid automated system

Introduction of the Vitek GNS-506 susceptibility testing cards in the Hippokration General Hospital, Thessaloniki, Greece, resulted in an apparently high prevalence of imipenem-resistant Acinetobacter baumannii. When 35 of these isolates were further tested by disk diffusion, broth microdilution, and agar dilution assays, 32 were imipenem sensitive by all tests and three were sensitive or intermediate, depending on the method. The pseudoresistant acinetobacters did not form a genetically homogeneous group. It is suggested that the detection of imipenem-resistant A. baumannii isolates by this system should be confirmed by an additional susceptibility test.