The association between risk factors and time of onset for thrombocytopenia in Japanese patients receiving linezolid therapy: a retrospective analysis

WHAT IS KNOWN AND OBJECTIVE

Linezolid (LZD) is an oxazolidinone antibiotic that is active against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. The major adverse effect related to its use in humans is reversible myelosuppression, which mostly manifests as thrombocytopenia. This retrospective study was conducted to identify risk factors that might contribute towards the development of thrombocytopenia due to intravenous administration of LZD.

METHOD

Patients who were administered LZD between January 2008 and March 2013 were included. Thrombocytopenia was defined as a decrease in platelet count of ≥10 × 10(4) cell/μL from baseline or of ≥30%.

RESULTS

A total of 47 patients were included in this study. These patients were divided into two groups: 22 patients (46·8%) were assigned to a non-thrombocytopenia group and 25 patients (53·2%) to a thrombocytopenia group. Multivariate logistic regression analysis revealed significant intergroup differences in duration of LZD treatment [odds ratio (OR) = 1·278; 95% confidence interval (CI) = 1·068-1·529; P = 0·007] and white blood cell (WBC) count (>12000 cells/μL; OR = 10·399; 95% CI = 1·667-64·882; P = 0·012).

WHAT IS NEW AND CONCLUSIONS

This finding suggests that duration of LZD treatment and WBC count (>12000 cells/μL) are risk factors associated with thrombocytopenia resulting from LZD administration.

Comparison of antibiotic susceptibility in viridans group streptococci in low and high antibiotic-prescribing General Practices

WHAT IS KNOWN AND OBJECTIVE

Antibiotic resistance has become a global public health issue. Most antibiotics are prescribed in the community, although there is less stewardship of such agents in the community compared to secondary and tertiary care. Few studies have attempted to examine the prescribing practices in General Practice and its impact on antibiotic resistance and, therefore, a study was performed in order to compare antibiotic susceptibilities of commensal viridans group streptococci (VGS) obtained from patient cohorts in General Practices (GP), who were high and low prescribers of oral antibiotics.

METHOD

Sixty-five patients (<1 month-81 years; 77% female: 23% male) were enrolled onto the study, and viridans group streptococci (n = 5/patient) were collected from each patient's nasal passages and oropharynx region and tested for antibiotic susceptibility against (i) tetracyclines (doxycycline); (ii) macrolides (erythromycin); (iii) β-lactams (penicillin G); and (iv) fluoroquinolones (ofloxacin & levofloxacin).

RESULTS AND DISCUSSION

There were no significant differences in MICs between high and low GP prescribers with doxycycline (P = 0·094), erythromycin (P = 0·122), ofloxacin (P = 0·193) and levofloxacin (P = 0·058). However, there was a significant difference between high and low GP practices with regard to penicillin G (P = 0·031). This finding is important as the β-lactams are the most commonly prescribed oral antibiotic in the community.

WHAT IS NEW AND CONCLUSION

This study demonstrates that high prescribing practices may lead to an altered (higher) level of resistance to these agents in the commensal VGS population, which may be important as reservoirs of antibiotic resistance determinants in subsequent horizontal gene transfer events, particularly with newly colonizing pathogens, including pneumococci. Primary care physicians should be aware that increased prescribing of antibiotics may led to increased level of penicillin resistance.

Usefulness of subtraction of 3D T2WI-DRIVE from contrast-enhanced 3D T1WI: preoperative evaluations of the neurovascular anatomy of patients with neurovascular compression syndrome

BACKGROUND AND PURPOSE

High-resolution 3D MR cisternography techniques such as 3D T2WI-driven equilibrium radiofrequency reset pulse (DRIVE) are used preoperatively to assess neurovascular anatomy in patients with neurovascular compression syndrome, but contrast between vessels and cranial nerves at the point of neurovascular contact is limited. The postprocessing technique subtraction of 3D T2WI-driven equilibrium radiofrequency reset pulse from contrast-enhanced 3D T1WI (sDRICE) provides both high spatial resolution and excellent contrast in depicting the neurovascular contact. We evaluated the usefulness of sDRICE compared with 3D T2WI-DRIVE.

MATERIALS AND METHODS

Twelve patients who underwent microvascular decompression for hemifacial spasm or trigeminal neuralgia were examined preoperatively with 3D T2WI-DRIVE and sDRICE. Two neuroradiologists retrospectively analyzed and scored lesion conspicuity, defined as the ease of discrimination between offending vessels and compressed nerves or the brain stem at the neurovascular contact. They also quantitatively analyzed the contrast and contrast-to-noise ratio at the neurovascular contact.

RESULTS

The lesion conspicuity scores of sDRICE images were significantly higher than those of 3D T2WI-DRIVE for all 12 patients (P = .006) and the 6 cases of hemifacial spasm (P = .023) but were not significantly higher in the 6 trigeminal neuralgia cases alone (P = .102). For all 12 patients, the contrast-to-noise ratio between the offending vessels and the brain stem and between the vessels and nerves on sDRICE images was significantly higher than that on 3D T2WI-DRIVE (P = .003 and P = .007, respectively). Among these structures, the contrast values were also significantly higher on the sDRICE than on the 3D T2WI-DRIVE (P < .001) images.

CONCLUSIONS

The postprocessing technique sDRICE is useful to evaluate neurovascular anatomy and to improve contrast and the contrast-to-noise ratio in patients with neurovascular compression syndrome.

Molecular characterisation of a type III restriction-modification system in Campylobacter upsaliensis

Two examples of Campylobacter upsaliensis RM3195 and JV21 strains are shown to carry putative type III restriction (res)-modification (mod) enzyme gene clusters, following genome sequence analyses. It is suggested that the cluster is composed of at least three structural genes, res, internal methylase gene and mod, in the strains, based on the nucleotide sequence information. A ribosome binding site, a putative promoter consisting of a consensus sequence at the -10-like structure and a semiconserved T-rich region and a putative intrinsic p-independent transcriptional terminator were identified for the gene cluster in the two strains. Using two primer pairs, f-/r-res and f-/r-mod, 34 of 41 C. upsaliensis isolates generated two expected amplicons of the res and mod gene segments, and using another primer pair, the same number of isolates also generated an amplicon of the res and mod gene segments cluster, including the third internal methylase gene. Thus, C. upsaliensis isolates frequently carried putative type III R-M gene clusters, encoding the three enzymes. Interestingly, two possible overlaps were identified within the three tandem structural genes. In addition, the type III R-M gene cluster loci appear to be very similar among the C. upsaliensis isolates and very different from other thermophilic campylobacters.

Features of an alternative hemodialysis method using a hemoconcentrator during cardiopulmonary bypass surgeries

Purpose:

This study clarified the features of a hemoconcentrator-based, alternative hemodialysis (ALTHD) method that improves the speed of serum potassium (K+) concentration adjustments, compared with dilutional ultrafiltration (DUF), during cardiopulmonary bypasses.

Methods:

Standardized bovine blood was recirculated (300 ml/min) through an in vitro hemoconcentrator circuit; hematocrit, K+ and glucose levels were measured at 5–20 min after DUF or ALTHD. We evaluated DUF at dialysis speeds of 50–250 ml/min and ALTHD at speeds of 50–1000 ml/min.

Results:

ALTHD rapidly corrected K+ and glucose concentrations at speeds up to 800 ml/min. ALTHD took 8.9 min to reach a K+ level of 4.5 mmol/L, faster than DUF (12.8 min). The ALTHD efficiency curves plateaued at 600 ml/min.

Conclusion:

ALTHD allowed faster adjustment of electrolyte levels, with peak efficiency at 600 ml/min. ALTHD has possible clinical application if available for potential use during all cardiopulmonary bypass surgeries involving extracorporeal circulation.

Construction and expression of a recombinant urease gene cluster from Campylobacter sputorum biovar paraureolyticus

Recombinant full-length urease gene cluster and seven 100% deletion recombinant variants of urease subunits genes, (ureG, ureH, ureA, ureB, ureC, ureE and ureF) were constructed in vitro from the Campylobacter sputorum biovar paraureolyticus LMG17591 strain and expressed in Escherichia coli JM109 cells. A urease-positive reaction (1.885 micromol/min/mg protein) in the log-phase cultured E. coli cells transformed with pGEM-T vector carrying the recombinant full-length urease genes cluster was detected. Among the seven 100% deletion recombinant variants, each of the ureG-, ureH(D)-, ureA-, ureB-, ureC-, ureE- and ureF-deletion variants showed no change in assay of the urease reaction, and similarly as in the E. coli cell lysate with pGEM-T vector only. Recombinant full-length urease gene cluster and 100% deletion recombinants of the ureE gene in the transformed and log-phase cultured E. coli cells from the C. sputorum showed positively accelerated urease activities when cultured in the medium containing NiCl2 (750 micromol/L), but no activity was accelerated in the C. sputorum cultured in NiCl2. In addition, thiourea (20 mmol/L) completely inhibited urease activities from all C. sputorum examined. The putative recombinant urease subunits A and C were immunologically identified by Western blot analysis with polyclonal anti-urease alpha (A) and beta (B), raised against Helicobacter pylori.

Pretreatment with buthionine sulfoximine enhanced uptake and retention of BSH in brain tumor

To determine the influence of buthionine sulfoximine (BSO) on boron biodistribution after sulfhydryl borane (BSH) administration for boron neutron capture therapy, the effectiveness of the combination of BSO with sulfhydril- (BSH) and non-sulfhydril (B12H12 and BNH3) boron compounds, and the interval between BSO and BSH administration, the retention of boron in tissues have been evaluated using a 9L rat tumor model. Simultaneous administration of BSH and BSO showed significantly higher boron accumulation compared to that without BSO, however there was no difference in tissue boron level between B12H12 and BNH3 administration with BSO or without BSO. The longer interval (6h) between BSH and BSO administration related to the highest boron concentration in the brain and subcutaneous tumors compared to shorter intervals (0.5, 3h). Boron concentration in subcutaneous and brain tumors was maintained for 6 and 12h after the administration of BSH following BSO pretreatment.

Molecular structural analysis of major outer membrane protein (MOMP) gene clusters in Campylobacter lari

Southern hybridisation shows that urease-negative (UN) Campylobacter lari JCM2530(T) carries two putative major outer membrane protein (MOMP) genes. Sequences of approximately 2.1 kbp, encoding non-coding (NC) regions, with possible open reading frames (ORFs) for MOMP (porA1 or porA2) of approximately 1.2 kbp, NC regions and partial and putative Cla_0435 or Cla_1109 ORFs were identified in all five UN C. lari isolates examined, following polymerase chain reaction (PCR) cloning and sequencing. Each putative MOMP structural gene carried start and stop codons and ribosome binding sites of 1236-1278 bp in length. The putative sigma70 transcriptional promoter and the hypothetical rho-independent transcription terminator structures were also seen. Using Northern hybridisation, there was in vivo monocistronic MOMP gene transcription. In addition, in a Japanese urease-positive thermophilic Campylobacter (UPTC) CF89-12 strain, the porA1 gene locus, including an extra gene (approximately 2000 bp in length) was identified. The extra gene may occur within the porA1 gene locus in the eight UPTC isolates of the 23 C. lari isolates examined. Thus, a genetic heterogeneity occurred within the porA1 gene locus from some of the C. lari organisms including the UPTC CF89-12.

Molecular cloning and characterisation of the methionine sulphoxide reductase A (msrA) gene locus in Campylobacter lari organisms

The methionine sulphoxide reductase A (msrA) gene and its adjacent genetic loci from urease-negative (UN) Campylobacter lari RM2100 and urease-positive thermophilic Campylobacter (UPTC)CF89-12 strains appear to be composed of a msrA structure gene (507 base pairs [bp]) and another five-gene cluster (approximately 6300 bp) in the same strand and direction. A primer pair (F1/R4-msrA) for polymerase chain reaction (PCR) amplification was designed to generate a product of approximately 900 bp of the msrA gene, including its adjacent genetic loci for the thermophilic Campylobacter organisms and generate an amplicon with 16 C. lari isolates (n = 4 for UN C. lari; n = 12 for UPTC). Following direct nucleotide sequencing, sequence analysis and nucleotide sequence alignment analysis, the putative full-length msrA gene from the 16 C. lari isolates showed high nucleotide sequence similarities (91.8-100%) to each other and relatively low similarity (69.3-71.8%) to three reference C. jejuni and C. coli strains. In addition, the msrA gene was transcribed in both the UPTC CF89-12 and NCTC12893 cells using reverse transcription PCR. An immunoreactively positive signal was identified in the UPTC CF89-12 and NCTC12893 cells with anti-UPTC MsrA synthetic peptide antibodies.

Competition between antiferromagnetism and ferromagnetism in Sr2RuO4 probed by Mn and Co doping

Spin-triplet superconductivity in Sr₂RuO₄ has attracted enormous interest. Like other unconventional superconductors, superconductivity in Sr₂RuO₄ is in close proximity to magnetic instability. Undoped Sr₂RuO₄ exhibits incommensurate antiferromagnetic (AFM) fluctuations, which can evolve into static, short-range AFM order via Ti doping. Moreover, weak ferromagnetic (FM) coupling in Sr₂RuO₄ has also been suggested by NMR/neutron scattering experiments and studies on Ca_2−xSr_xRuO₄ and Sr_2−yLa_yRuO₄, implying orbital dependent magnetism. We report bulk static, short-range FM order in Sr₂RuO₄ triggered by <2% Co doping, showing superconductivity in Sr₂RuO₄ is much closer to FM instability than previously reported in Ca_2−xSr_xRuO₄. We also find Mn doping can effectively establish incommensurate AFM order, with T_N ~ 50 K for 3% Mn doping. These new results place Sr₂RuO₄ in a unique situation where superconductivity lies directly on the borderline of two distinct magnetic states, highlighting the important role of competing magnetic fluctuations in determining superconducting properties of Sr₂RuO₄.

Prospects for using a hemoconcentrator as an alternative hemodialysis method in cardiopulmonary bypass surgeries

Objective:

Cardioplegic solutions often cause high blood concentrations of potassium. The conventional hemoconcentration circuit was improved to correct electrolyte imbalances through a method involving dilutional ultrafiltration (DUF) and an alternative hemodialysis (ALTHD) method. This study aimed to determine the effectiveness of this ALTHD method.

Methods:

Bovine blood was used, in conjunction with a hemoconcentrator, in an experimental hemodialysis (HD) circuit to evaluate an ALTHD method. The effectiveness of the method was determined by electrolyte and hematocrit measurements following the procedure.

Results:

The ALTHD method corrected electrolyte levels as effectively as DUF and was less affected by dilution than DUF.

Conclusion:

The ALTHD method may provide faster electrolyte adjustments than DUF because its efficiency depends on both the blood and dialysate flow rates. In addition, the ALTHD method is expected to provide increased efficiency. Thus, our DUF/ALTHD circuit-switching method may be clinically useful when rapid electrolyte correction is required.

Construction, expression and characterisation of recombinant molecules of the urease gene operon from a urease-positive thermophilic Campylobacter (UPTC) isolate

A recombinant molecule of the full-length urease gene operon was constructed in vitro from the Japanese urease-positive thermophilic Campylobacter (UPTC) CF89-12 isolate and expressed in Escherichia coli cells. Several large deletion recombinant variants of urease subunit genes were also constructed and expressed in E. coli cells. A positive urease reaction with the log-phase cultured E. coli JM109 cells in the NiCl2-containing medium transformed with pGEM-T vector carrying the recombinant molecule of the full-length operon was detected with isopropyl-beta-D-thiogalactoside. Among the several deletion recombinant variants, each ureA-, ureB-, ureE-, ureF-, ureG- and ureH-large deficient, only ureE-large deletion variant (63% deficient) showed a positive urease reaction (approximately 15-fold). In addition, a ureE-complete deletion recombinant variant (100% deficient) constructed also showed a positive reaction of urease (approximately 18-fold). Recombinant urease subunits A and B were immunologically identified by Western blot analysis with anti-urease alpha (A) and beta (B) raised against Helicobacter pylori.

Effect of electron correlations on magnetic excitations in the isovalently doped iron-based superconductor Ba(Fe(1-x)Ru(x))(2)As(2)

Magnetic correlations in isovalently doped Ba(Fe(1-x)Ru(x))(2)As(2) (x = 0.25, T(c) = 14.5 K; x = 0.35, T(c) = 20 K) are studied by elastic and inelastic neutron scattering techniques. A relatively large superconducting spin gap accompanied by a weak resonance mode is observed in the superconducting state in both samples. In the normal state, the magnetic excitation intensity is dramatically reduced with increasing Ru doping toward the optimally doped regime. Our results favor that the weakening of the electron-electron correlations by Ru doping is responsible for the dampening of the resonance mode, as well as the suppression of the normal state antiferromagnetic correlations near the optimally doped regime in this system.

Molecular identification of an arsenic four-gene operon in Campylobacter lari

An arsenic (ars) four-gene operon, containing genes encoding a putative membrane permease (ArsP), a transcriptional repressor (ArsR), an arsenate reductase (ArsC) and an arsenical-resistance membrane transporter (Acr3) was first identified in urease-positive thermophilic Campylobacter (UPTC) isolate, CF89-12. UPTC CF89-12 and some other Campylobacter lari isolates contained their ars four-genes, similarly, differing from that in the reference C. lari RM2100 strain. Two putative promoters and a putative terminator were identified for the operon in UPTC CF89-12. In vivo transcription of the operon was confirmed in the UPTC cells. PCR experiments using two primer pairs designed in silico to amplify two arsR and arsC-acr3 segments, respectively, generated two amplicons, approximately 200 and 350 base pairs, with all 31 of 31 and 19 of 31 C. lari isolates (n = 17 for UPTC; n = 14 for UN C. lari), respectively. An inverted repeat forming a dyad structure, a potential binding site for a transcriptional repressor, was identified in the promoter region. Within the deduced 61 amino acids sequence of the putative arsR open reading frame from the UPTC CF89-12, a metal binding box and a DNA-binding helix-turn-helix motif were identified. The UPTC CF89-12 and some other UPTC isolates isolated from natural environment were resistant to arsenate.

Transparent-Scaled Variant of the Rosy Bitterling, Rhodeus ocellatus ocellatus (Teleostei: Cyprinidae)

Transparent-scaled variant (TSV) of the rosy bitterling Rhodeus ocellatus ocellatus (Kner) was observed on both morphology and heredity. Compared with the normal-scaled type (NST), TSV is characterized by the blackish coloration in both eyes and peritoneum, and the luminescent one over the whole body. Histologically, the density of guanophores containing reflecting platelets was conspicuously low, especially in scale, iris, choroid and peritoneum, while the increase in the number of goblet cells (mucous cells) was recognized all over the dermal/epidermal regions. The heredity of TSV was recessive and supposed to be controlled by a single pair of genes unrelated to sex, judging from the result of crossbreeding experiments between NST and TSV. In growth and reproduction, no difference was seen between these two phenotypes. Transparent-scaled variant of the rosy bitterling can be competent for a genetic marker in experimental and developmental biology.