Emergent Spin-Gapped Magnetization Plateaus in a Spin-1/2 Perfect Kagome Antiferromagnet.

The two-dimensional spin-1/2 kagome Heisenberg antiferromagnet is believed to host quantum spin liquid (QSL) states with no magnetic order, but its ground state remains largely elusive. An important outstanding question concerns the presence or absence of the 1/9 magnetization plateau, where exotic quantum states, including topological ones, are expected to emerge. Here we report the magnetization of a recently discovered kagome QSL candidate YCu_{3}(OH)_{6.5}Br_{2.5} up to 57 T. Above 50 T, a clear magnetization plateau at 1/3 of the saturation moment of Cu^{2+} ions is observed, supporting that this material provides an ideal platform for the kagome Heisenberg antiferromagnet. Remarkably, we found another magnetization plateau around 20 T, which is attributed to the 1/9 plateau. The temperature dependence of this plateau reveals the presence of the spin gap. The observation of 1/9 and 1/3 plateaus highlights the emergence of novel states in quantum spin systems.

Nosocomial Candida parapsilosis candidaemia: risk factors, antifungal susceptibility and outcome.

A retrospective analysis was undertaken from 2000 to 2010 to show the risk factors associated with death within 30 days in patients with C. parapsilosis candidaemia (CPC). Fifty-one cases of nosocomial CPC were included in the analysis. All isolates from blood cultures were susceptible to micafungin and fluconazole. The overall mortality rate was 23.5%, and the most severe complications were endocarditis (5.9%) and endophthalmitis (5.9%). On multi-variate analysis, APACHE II score >25 (odds ratio 43.9) and retained cardiovascular prosthetic materials (RCPM) (prosthetic valve or graft) (odds ratio 14.6) were found to be risk factors associated with death. Prompt surgical removal should be considered in CPC patients with RCPM.

Low serum potassium levels and risk of type 2 diabetes: the Toranomon Hospital Health Management Center Study 1 (TOPICS 1).

AIMS/HYPOTHESIS: Evidence has suggested that low serum potassium concentrations decrease insulin secretion, leading to glucose intolerance, and that hypokalaemia induced by diuretics increases the risk for diabetes in hypertensive individuals. However, no prospective study has investigated the association between serum potassium and the development of type 2 diabetes in a healthy cohort comprised of Asian individuals not being administered antihypertensive medications. This study aimed to investigate whether low serum potassium is associated with increased risk of type 2 diabetes in apparently healthy Japanese men. METHODS: We followed 4,409 Japanese men with no history of diabetes, use of antihypertensives, renal dysfunction or liver dysfunction (mean ± SD age, 48.4 ± 8.4 years). Cox proportional hazards regression was used to estimate HRs for incident diabetes (fasting plasma glucose level ≥ 7.0 mmol/l, HbA(1c) ≥ 6.5% or self-reported) including serum potassium concentration as either a categorical or a continuous variable. RESULTS: During a 5 year follow-up, 250 individuals developed type 2 diabetes. The lowest tertile of serum potassium (2.8-3.9 mmol/l) was independently associated with the development of diabetes after adjustment for known predictors (HR 1.57 [95% CI, 1.15-2.15]) compared with the highest tertile (4.2-5.4 mmol/l). Every 0.5 mmol/l lower increment in the baseline serum potassium level was associated with a 45% (12-87%) increased risk of diabetes. CONCLUSIONS/INTERPRETATION: Mild to moderately low serum potassium levels, within the normal range and without frank hypokalaemia, could be predictive of type 2 diabetes in apparently healthy Japanese men.

Factors associated with inappropriate weight loss attempts by early adolescent girls in Japan.

Attempting to lose weight by normal or underweight adolescent girls is a serious issue in many countries. It has been reported that the mode of attempted weight loss does not differ between normal weight and overweight girls. These inappropriate weight loss attempts (IWLA) by normal or underweight adolescent girls is associated with various health issues, but factors associated with IWLA have only been marginally elucidated. In this study, we applied a single multivariate regression analysis to clarify independent factors for IWLA. Study subjects were 134 pairs of early adolescent girls (aged 12-15) and their mothers. In addition to IWLA, many factors including height, weight, body image, perceived weight status, depressive symptoms, media influence and self-esteem were surveyed in both mothers and daughters and subjected to multivariate analysis. Approximately half of girls surveyed had IWLA, even though all were of normal weight and 62.9% knew that they were of normal weight. IWLA were independently associated with depressive symptoms (OR (95% CI); 2.80 (1.21-6.50), p=0.016) independent of actual or perceived weight status. Factors significantly associated with IWLA by the girls were percentage deviation of weight from standard weight (%DW) and media influence on the girls themselves, and media influence on and self-esteem of their mothers. IWLA, which were frequently observed among early adolescent girls even among those of normal weight, were closely related to depressive status. IWLA were significantly associated with not only factors related to the girls (1.09 (1.04-1.14), p=0.001), but also with maternal psychological factors (1.06 (1.00-1.13), p=0.035) conveyed by the media. Future prospective or interventional studies are required to clarify whether these factors could be targeted in an effort to prevent IWLA.

Distribution of emm genotypes and superantigen genes of Streptococcus pyogenes isolated in Japan, 1994-9.

The purpose of this study was to examine characteristic profiles of Streptococcus pyogenes clinical isolates isolated in Japan during 1994-9. Genotyping of the M protein (emm typing) revealed that emm types 12 and 28 were the most common among 316 isolates. Most of the emm12 isolates were isolated from mucosa, while emm58 and emm89 were from skin. Moreover, the emm3 isolates were dominant in invasive infections. The distribution of 6 superantigen genes showed that all isolates harboured the mf gene and many had the speG gene. Invasive isolates were shown to have the ssa gene at a higher rate (76%) than noninvasive (37%). The distribution of superantigens was significantly different between emm types, but not between isolation sites. These results suggest that the distribution of emm types is related to isolation site, whereas superantigen distribution is related to clinical features of S. pyogenes infections.

[A Case of central venous catheter-related infection with Malassezia sympodialis].

We report a 63-year-old male with central venous catheter-related infection caused by Malassezia sympodialis after total gastrectomy for a gastric cancer. He had fever and his leukocyte counts and C-reactive protein were elevated 14 days after his operation. After his central venous hyperalimentation catheter was removed, the inflammatory signs immediately disappeared, suggesting an intravenous catheter-related infection. A yeast-like fungus was cultured in brain-heart infection semi-solid agar ten days later, and was diagnosed morphologically as Malassezia sp. This strain was identified as M. sympodialis by Tween assimilation test and was confirmed by whole-sequence of internal transcribed spacer 1 regions (ITS1). This is the first report of catheter-related infection caused by M. sympodialis. This strain grew and was subcultured on CHROMagar Candida, potato dextrose agar and Sabouraud agar. There have been no reports of such a lipid-independent Malassezia sp. except for M. pachydermatis. The mechanism of lipid independence of this strain is undetermined and future work is needed. Malassezia sp. is receiving increased attention as an etiologic pathogen of catheter-related fungemia in clinical microbiology laboratories and infectious disease sections.

Effects of food intake and age on the pharmacokinetics of AS-924, a novel ester-type cephem antibiotic. Comparison with cefpodoxime proxetil.

The effects of food intake and age on intestinal absorption of AS-924, a novel prodrug-type cephem antibiotic, were examined in 16 healthy adult volunteers (eight young volunteers and eight elderly volunteers) by the cross-over method, using cefpodoxime proxetil (CPOD-PR) as the control drug. The gastrointestinal absorption of AS-924 and CPOD-PR was increased slightly by food intake and the extent of increase was slightly greater after administration of CPOD-PR. The absorption of AS-924 was not affected by age, whereas intestinal absorption of CPOD-PR increased with age. In conclusion, these results confirmed that AS-924 has the unique characteristics as a novel prodrug and that its absorption is less likely to be affected by food intake and age.

Effect of antacid pretreatment on the pharmacokinetics of AS-924, a novel ester-type cephem antibiotic--comparison with cefteram-pivoxil.

The effect of pretreatment with ranitidine, an antacid, on the absorption of AS-924, a novel prodrug-type cephem antibiotic derived from ceftizoxime (CTIZ), was examined in eight healthy adult male volunteers by the cross-over method, using cefteram-pivoxil (CTER-PI) as the control drug. The C(max) and area under the concentration (AUC) values and cumulative urinary excretion rate (0-24 h) of cefteram (CTER) after administration of CTER-PI decreased by 32, 38 and 37%, respectively, in the ranitidine pretreatment group whereas those of AS-924 were not affected by the antacid. The urinary levels of pivaloyl-carnitine determined to evaluate the solubility of these antibiotics in the gastrointestinal tract suggested that this was not affected by ranitidine. These results indicate that the absorption of CTER-PI was affected by pretreatment with ranitidine largely due to inactivation of this antibiotic in the gastrointestinal tract at high pH rather than to a decrease in solubility. In contrast, isomerization of AS-924 was hardly induced by the elevation of pH, thus demonstrating that AS-924 was less likely to be affected by pretreatment with antacids.

Inhibition of methicillin-resistant Staphylococcus aureus colonization of oral cavities in newborns by viridans group streptococci.

We investigated the role of viridans group streptococci in the prevention of colonization with methicillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units. During a 26-month period at a children's hospital, 207 (49.9%) of 415 newborns were colonized with MRSA by the time of discharge. Two groups of newborns with matching durations of hospitalization were compared with regard to the prevalence of future colonization with MRSA: group 1 (103 patients) did not acquire colonization with viridans group streptococci and group 2 (63 patients) did acquire colonization with viridans group streptococci at birth or by 1 to 2 weeks (age, < or =11 days). The rate of colonization among patients in group 2 (9.5%) was significantly lower than that among patients in group 1 (44.7%; P<.001). No significant difference in patient characteristics (e.g., birth weight, diseases) was observed. These results indicate that viridans group streptococci, as bacteria that formerly occupied the oral cavities in newborns, may inhibit later colonization with MRSA.

H(2)O(2) produced by viridans group streptococci may contribute to inhibition of methicillin-resistant Staphylococcus aureus colonization of oral cavities in newborns.

In an accompanying report, we showed that viridans group streptococci may prevent methicillin-resistant Staphylococcus aureus (MRSA) colonization of the oral cavities of newborns. In the present study, we investigated the mechanism of prevention in vitro. Most viridans group streptococci had bacteriocin-like activity and killed MRSA, Burkholderia cepacia, Enterobacter aerogenes, and Pseudomonas aeruginosa; however, Escherichia coli, Enterobacter cloacae, and Candida albicans were resistant. The activity was induced only by H(2)O(2)-secreting strains and was inhibited by horseradish peroxidase or catalase in a dose-dependent manner. The mean concentration of H(2)O(2) produced by 18 strains of viridans group streptococci (1 x 10(8) cfu in 200 microL of culture medium+/-standard deviation was 1.24+/-0.60 mmol. Viridans group streptococci inhibited MRSA growth in saliva as well as in culture media. These results indicate that H(2)O(2) produced by viridans group streptococci may inhibit MRSA colonization of oral cavities in newborns.

Low-lying magnetic excitation of the Shastry-Sutherland model.

By using perturbation calculation and numerical diagonalization, the low-energy spin dynamics of the Shastry-Sutherland model is investigated with particular attention to the two-particle coherent motion. In addition to spin-singlet- and triplet-bound states, we find novel branches of coherent motion of a bound quintet pair, which are usually unstable because of repulsion. Unusual dispersion observed in neutron-scattering measurements is explained by the present theory. The importance of the effects of phonons is also pointed out.

Recurrent septicemia caused by Streptococcus canis after a dog bite.

Human infection with Streptococcus canis is extremely rare. We describe herein a case of septicemia with cellulitis caused by S. canis in a 75-y-old woman, which developed 2 weeks after a dog bite. Macrorestriction analysis with pulsed-field gel electrophoresis demonstrated that the organism had been transmitted by means of a dog bite to her hand.

Similarity of antibiotic resistance patterns and molecular typing properties of methicillin-resistant Staphylococcus aureus isolates widely spread in hospitals in New York City and in a hospital in Tokyo, Japan.

One hundred and forty-three single-patient methicillin-resistant Staphylococcus aureus (MRSA) isolates collected during April-June, 1997, and February, 1998, in a hospital in Tokyo, Japan, were characterized by molecular typing techniques that involved hybridization of ClaI restriction digests with the mecA- and Tn554-specific DNA probes and determination of macrorestriction patterns of SmaI-digested chromosomal DNA by pulsed-field gel electrophoresis (PFGE). A large proportion (76%) of the isolates carried the mecA polymorph I, Tn554 pattern A, and PFGE pattern A (clonal type I:A:A), which was the same as the clonal type of an MRSA widely spread in hospitals in New York City and hospitals in neighboring New Jersey, Connecticut, and Pennsylvania. Also similarly to the New York clone, most of the MRSA isolates from the Japanese hospital were resistant to penicillin, ciprofloxacin, erythromycin, tetracycline, and high concentrations (500 microg/ml) of spectinomycin, but were susceptible to chloramphenicol, sulfamethoxazole-trimethoprim, and rifampin. All of the 143 MRSA isolates had vancomycin MICs < or = 2 mg/L.

Combined effects of vancomycin and imipenem against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo.

Infectious disease caused by methicillin-resistant Staphylococcus aureus (MRSA) often develops in compromised hosts in whom a single administration of vancomycin is usually not effective. We assessed the combined antimicrobial effects of vancomycin and imipenem against MRSA growth in vitro as well as in vivo using a neutropenic mouse thigh infection model. Synergic and additive effects of the two drugs were observed for 34 and two, respectively, of the 36 clinical isolates of MRSA, as determined by the chequerboard method. For MRSA strain N, postantibiotic effect (PAE) values obtained in vitro were 1.9-2.6 h for vancomycin and 2.6-3.5 h for imipenem, while higher values of 2.7-4.4 h were obtained for the combination of vancomycin and imipenem. In vivo, a single administration of vancomycin at 1 or 2 mg/kg or of imipenem/cilastatin at 5 mg/kg produced growth curves similar to those in controls, with a suppressive time of 0 h. Imipenem/cilastatin at 10 mg/kg demonstrated a suppressive time of 3.1 h. Combinations of vancomycin 1 mg/kg plus imipenem/cilastatin 5 mg/kg, vancomycin 1 mg/kg plus imipenem/cilastatin 10 mg/k and vancomycin 2 mg/kg plus imipenem/cilastatin 10 mg/kg demonstrated suppressive times of 2.9, 3.9 and 5.2 h, respectively, indicating that combined administration was effective. Simultaneous administration of the two drugs was more effective than sequential administration. Thus, combined administration of vancomycin and imipenem/cilastatin proved effective for MRSA in vivo. The combined effects seemed to be synergic, since a single administration of either drug did not show anti-MRSA effects at the doses used in the combined regimen.

Cascade of acetazolamide-induced vasodilatation.

UNLABELLED: Acetazolamide (AZ) has been found to be effective in inducing vasodilatation. To evaluate the mechanism by which AZ acts, we compared the effects of this agent on vascular PGI2, endothelin (ET-1), and NOx, with those induced by CO2 gas inhalation. METHOD: Blood flow (BF) was measured in the liver, kidneys, stomach wall, and abdominal muscle of anesthetized white rabbits with a laser flow meter at baseline and again after sequential doses of AZ (4 mg/kg) or CO2 inhalation. Cardiac output and serum concentrations of PGI2, ET-1, and NOx were also measured in these animals. RESULTS: AZ increased BF in the liver and kidneys, but had no effect on BF in the stomach wall or abdominal muscle. The level of NOx was decreased following the administration of AZ, while PGI2 and ET-1 levels remained unchanged. In contrast, CO2 inhalation increased PCO2, and decreased pH, significantly. CO2 elevated BF in the liver, kidneys, stomach wall, and abdominal muscle, as well as serum levels of PGI2 and ET-1, while having no effect on NOx levels. The alterations in BF, PGI2, ET-1, and NOx in response to AZ, suggest that the mechanism of AZ-induced vasodilatation may involve a cascade that is triggered by CO2 retention similar to that caused by the inhalation of CO2.

Comparison of pathogenic factors expressed by group A Streptococci isolated from patients with streptococcal toxic shock syndrome and scarlet fever.

Streptococcal toxic shock syndrome (STSS) is an illness with high mortality. To obtain clues to understanding the pathogenesis of STSS, we investigated the expression of several pathogenic factors in ten group A streptococcus (GAS) isolates from ten patients with STSS in Japan, in comparison with ten GAS isolates from children with scarlet fever. The ten scarlet fever-derived GAS isolates were equally low in lethality and anti-phagocytic activity in mice and in the production of streptolysin O (SLO), and equally high in production of superantigenic exotoxins (SAGTs) and cysteine proteinase. By comparison, the ten STSS-derived GAS isolates were heterogeneous in the expression of the above pathogenic factors, which ranged from low to high values. Most of the ten STSS-derived isolates were higher in lethality and anti-phagocytic activity and production of SLO, and lower in the production of SAGTs and cysteine proteinase than the ten scarlet fever-derived isolates. The results suggest that the lethality and anti-phagocytic activity examined in mice and SLO may be involved mainly in the development of most of the ten STSS cases.