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Competing Interests: Competing interests: None declared.

Chiral and molecular recognition through protonation was investigated through the collision-activated dissociation (CAD) of protonated noncovalent complexes of aromatic amino acid enantiomers with l-alanine- and l-serine-containing tripeptides using a linear ion trap mass spectrometer. In the case of l-alanine-tripeptide (AAA), NH₃ loss was observed in the CAD of heterochiral H⁺(d-Trp)AAA, while H₂O loss was the main dissociation pathways for l-Trp, d-Phe, and l-Phe. The protonation site of heterochiral H⁺(d-Trp)AAA was the amino group of d-Trp, and the NH₃ loss occurred from H⁺(d-Trp). The H₂O loss indicated that the proton was attached to the l-alanine tripeptide in the noncovalent complexes. With the substitution of a central residue of l-alanine tripeptide to l-Ser, ASA recognized l-Phe by protonation to the amino group of l-Phe in homochiral H⁺(l-Phe)ASA. For the protonated noncovalent complexes of His enantiomers with tripeptides (AAA, SAA, ASA, and AAS), protonated His was observed in the spectra, except for those of heterochiral H⁺(d-His)SAA and H⁺(d-His)AAS, indicating that d-His did not accept protons from the SAA and AAS in the noncovalent complexes. The amino-acid sequences of the tripeptides required for the recognition of aromatic amino acids were determined by analyses of the CAD spectra., Competing Interests: The authors declare no conflict of interest.

A 46-year-old man presented with a 10-day history of progressive weakness and numbness in both his legs. The spinal MRI and abdominal CT revealed discitis of L4/L5 and multiple epidural abscesses. The blood culture tested positive for methicillin sensitive Staphylococcus aureus (MSSA). The Gram stain of sample from abscess drainage showed Gram-positive cocci in clusters and small Gram-negative rods. The Gram-positive cocci in clusters were identified as MSSA using a general culture method and the small Gram-negative rods were identified as Aggregatibacter aphrophilus using a 16s ribosomal RNA sequencing method. The patient was treated four times with surgical abscess drainages and a long course of intravenous antibiotics therapy following which he recovered. No case of mixed infection by A. aphrophilus and S. aureus has been reported in MEDLINE; therefore, our case should be the first case report. Since we confirmed not only Gram-positive cocci in clusters but also Gram-negative rods in the abscess sample, we did not stop the identification procedure at the point when MSSA was identified and finally identified A. aphrophilus with 16s ribosomal RNA sequencing. Especially, in a mixed infection with organisms whose growth speed is different, an organism with slow growth might be missed if the Gram stain of sample were skipped. This case implies the significance of Gram staining as the identification procedure for organisms.

We report herein on a case of Plasmodium malariae malaria with more than a 4-month incubation period. A 35-year-old Japanese man who first presented to our clinic with fever and history of travel to Papua New Guinea was suspected of having Plasmodium vivax malaria based on peripheral smear results. We admitted him and initiated treatment with mefloquine. After two days of therapy, he became afebrile. We discharged him, and P. vivax was later confirmed with PCR. We started mefloquine prophylaxis for a planned trip to Papua New Guinea. After his return, a standard dose of primaquine (15 mg x 14 days) was prescribed for a radical cure of P. vivax. About 4 months after his last visit to Papua New Guinea, he returned to our clinic with fever. We suspected a relapse of P. vivax malaria and admitted him for a second time. After two days of mefloquine therapy, his symptoms improved. We discharged him and restarted a higher dose of primaquine (30 mg x 14 days) therapy for a radical cure of P. vivax. Subsequently, the PCR test revealed the parasite was P. malariae and not P. vivax. Only 13 cases of Plasmodium malariae malaria have been reported in Japan during the past 10 years. Blood-stage schizonticides such as mefloquine is not active against the liver stage. Therefore, the use of these drugs for prophylaxis will not be effective for prevention of malaria if its liver stage is longer than the duration of effective chemoprophylaxis. Although the incubation period of P. malariae is typically 13 to 28 days, it occasionally lasts for months or even years. Careful attention should be given to the possibility that P. malariae occasionally has a long incubation period even in the absence of the hypnozoite stage.

We report an extremely rare case of urosepsis caused by Globicatella sanguinis and Corynebacterium riegelii coinfection in a 94-year-old Japanese man with nephrolithiasis. Prompt identification of this coinfection is important so that effective antimicrobial coverage can be initiated.

Background: The infectious diseases (ID) consultation service is a new clinical entity in Japan. We examined the impact of ID consultation on the diagnosis of infective endocarditis (IE) at a large teaching hospital in Japan., Methods: Routine consultation with an ID service for cases of positive blood culture was implemented at Kameda Medical Center in November 2004. In addition, ID service doctors started to give lectures on ID to doctors and also provided local guidelines on ID. We compared the incidence of IE during a 3-y and 10-month period before intervention with that during a 5-y and 2-month period after intervention. The modified Duke criteria were used to confirm the diagnosis of definite IE. Patients who fulfilled the criteria for definite IE were included in the analysis., Results: Twenty-seven cases of IE were diagnosed before the implementation of routine consultation, and 76 cases after. The respective incidences of IE were 48.7 and 84.8 per 100,000 patients discharged from the hospital (p = 0.01). The relapse rate of IE within 6 months was significantly lower in patients who underwent routine consultation (22.2% vs 2.2%; p = 0.02)., Conclusion: Routine consultation with an ID service for cases of positive blood culture, together with consecutive lecturing and local guidelines by ID specialists, resulted in improved detection of IE and a reduced relapse rate within 6 months. Timely consultation with an ID specialist in bacteraemia cases may be beneficial for improving the outcomes of patients in this setting.

Theoretical and synthetic studies of the tricyclic 10pi-electron hydrocarbon cyclobuta[1,2:3,4]dicyclopentene (1), a nominally aromatic structure that has never been synthesized, are described. Geometry optimization by density-functional-theory calculations (B3LYP/6-31G(d,p)) predict that 1 is a D(2h) symmetric structure with nonalternant C-C single and double bonds. The calculations also predict that 1 is 4.7 kcal/mol higher in energy than the isomeric hydrocarbon 1,6-didehydro[10]annulene (2), a molecule known to isomerize to 1,5-didehydronaphthalene (4) above -50 degrees C. Calculated enthalpic changes of homodesmotic reactions support the notion that 1 is an aromatic molecule with a resonance stabilization energy (RSE) about half to two-thirds that of benzene on a per-molecule basis. Investigations of potential synthetic pathways to 1 initially utilized as starting material the tricyclic carbonate 11, the product of an intramolecular [2 + 2]-photocyclization reaction. In these studies, 11 was transformed in several steps to the distannane 12, which upon treatment with boron fluoride ethyl etherate is believed to have formed the unstable hydrocarbon bicyclopentadienylidene (13). In an effort to avoid cleavage of the central, four-membered ring of unsaturated tricyclo[5.3.0.0(2,6)]decane intermediates (perhaps the result of 10-electron electrocyclic ring opening of the tetraene 8), synthetic approaches to 1 employing cobalt-cyclobutadiene complexes 18 and 19 were pursued. Treatment of 18 with excess methyllithium led to the novel cobaltacyclic product 30, and dehydration of 19 in the presence of pyridine produced the ring-opening cobaltacyclic product 35. It is proposed that both processes may occur by a 10-electron electrocyclic ring-opening reaction of eta(2)-organocobalt intermediates. These processes may be related to the hypothetical transformation of tetraene 8 to bicyclopentadienylidene (13).