Characteristics and disease severity of healthcare-associated pneumonia among patients in a hospital in Kitakyushu, Japan.

Healthcare-associated pneumonia (HCAP) is a newly identified condition, and epidemiologic studies in Japan are still limited. We retrospectively observed patients with HCAP and community-acquired pneumonia (CAP) who were hospitalized between December 2004 and March 2005, and compared their disease characteristics. A total of 34 patients (14 with HCAP and 20 with CAP) were evaluated. Of the patients with HCAP, seven (50%) were hospitalized for at least 2 days in the preceding 90 days and five (35.7%) resided in a nursing home or extended care facility. Compared with patients with CAP, patients with HCAP were older, had more complications, including central nerve diseases, had greater disease severity, but lower serum albumin level. More methicillin-resistant Staphylococcus aureus, Pseudomonas spp., and anaerobes were isolated from patients with HCAP than from those with CAP. Conversely, more Streptococcus pneumoniae was detected and more penicillin was used in patients with CAP. This study provides additional evidence that HCAP should be distinguished from CAP and suggests the pathogenesis and therapeutic strategy for HCAP may be similar to those for hospital-acquired pneumonia

Stable Push–Pull Disilene: Substantial Donor–Acceptor Interactions through the SiSi Double Bond

The push–pull effect has been widely used to effectively tune π-electron systems. Herein, we report the synthesis and properties of 1-amino-2-boryldisilene <b>1</b> as the first push–pull disilene. Its spectroscopic and structural features show substantial interactions between the SiSi double bond and the amino and boryl substituents. The π → π* absorption band of <b>1</b> is remarkably red-shifted compared to that of the corresponding alkyl-substituted disilene <b>2</b>. Treatment of <b>1</b> with H₂ resulted in the cleavage of two molecules of H₂ under concomitant formation of the corresponding trihydridodisilane and hydroborane

Pentasila-1,4-diene: Homoconjugation between SiSi Double Bonds via a SiMe₂ Unit

Although the synthesis of several bis­(disilenes) has already been reported, the number of reported conjugation modes between the SiSi double bonds remains limited. Herein, we report the properties of the stable pentasila-1,4-diene <b>1</b>, which was obtained from the reaction of two equivalents of disilenide <b>4</b> with dichlorodimethylsilane. The π­(SiSi)→π*­(SiSi) absorption band of <b>1</b> is considerably broadened and red-shifted compared to those of the corresponding monodisilene and hexasila-1,5-diene, but blue-shifted relative to those of typical tetrasila-1,3-dienes. The bathochromic shift and the broadening of the absorption band in <b>1</b> should be attributed to the homoconjugation between SiSi double bonds through the SiMe₂ unit

Dialkylboryl-Substituted Cyclic Disilenes Synthesized by Desilylation-Borylation of Trimethylsilyl-Substituted Disilenes

π-Electron systems of silicon have attracted attention because of their narrow HOMO-LUMO gap and high reactivity, but the structural diversity remains limited. Herein, new dialkylboryl-substituted disilenes were synthesized by the selective desilylation-borylation of the corresponding trimethylsilyl-substituted disilenes. The dialkylboryl-substituted disilenes were fully characterized by a combination of NMR spectroscopy, MS spectrometry, single-crystal X-ray diffraction analysis, and theoretical calculations. The longest-wavelength absorption bands of boryldisilenes were bathochromically shifted compared to the corresponding silyl-substituted disilenes, indicating a substantial conjugation between π(Si=Si) and vacant 2p(B) orbitals. In the presence of 4-(dimethylamino)pyridine (DMAP), the dialkylboryl groups in the boryl-substituted disilenes were easily converted to trimethylsilyl groups, suggesting the dialkylboryl-substituted disilenes in the presence of a base serve as the surrogates of disilenyl anions (disilenides)