Organometallic dehydro[14] annulenes containing Vollhardt's cyclobutadiene: are CpCo-complexed cyclobutadienes more aromatic then benzene?

Pd-catalyzed coupling of 1,2-diethynyl-3,4-(bistrimethylsilyl)cyclobutadienecyclopentadienylcobalt to a series of 1-iodo-2-(trimethylsilylethynyl)benzenes and 1-chloro-4-trimethylsilylbut-1-ene-3-yne is followed by desilylation with potassium carbonate. Cu(OAc)(2)-promoted oxidative ring closure leads to dehydro[14]annulenes and dehydro[14]benzoannulenes fused to a cyclobutadiene(cyclopentadienylcobalt) complex. Five of these fused dehydroannulenes were structurally characterized. (1)H NMR spectroscopy of the organometallic dehydro[14]annulenes incorporating the (bistrimethylsilyl)cyclobutadiene(cyclopentadienylcobalt) unit suggested that the aromaticity of the fused cyclobutadiene complex might be stronger than that of benzene according to the ring-current criterion.

Streptobacillus moniliformis infection in Swiss white mice.

An epizootic of disease attributed to infection with Streptobacillus moniliformis occurred in a colony of Swiss white mice. The mortality rate among the 180 breeding females in the 6 affected pens was 100%, and most of the sucking young died from starvation. Acute septicemia, subacute septicemia, and polyarthritis were the 3 forms of disease observed. Clinically, septicemic mice either were found dead or were depressed and hunched for 1-2 days prior to death. About a half of these mice had brown skin crusts overlying the mammae. Pathologic findings in cases of acute septicemia were few; in mice with subacute septicemia, there was acute, multifocal, suppurative, embolic interstitial nephritis, and the arthritic form was characterized by many subcutaneous and periarticular abscesses. Severe, acute, diffuse neutrophilic dermatitis was responsible for the brown skin crusts. The S. moniliformis isolate conformed morphologically and physiologically to classical descriptions of the organism. The infection may have gained entry to the colony via wild rats.

Effects of some clinically significant mycotoxins on the incorporation of DNA, RNA and protein precursors in cultured mammalian cells.

The effects of zearalenone (F-2), ochratoxin A and T-2 toxins on the synthesis of DNA, RNA and proteins in mouse L cells were studied. F-2 toxin inhibited protein synthesis to a lesser extent than DNA and RNA synthesis, whereas ochratoxin A inhibited the synthesis of each equally. Exposure to the toxins for 24 hours relatively reduced the synthetic ability of the cells. T-2 toxin inhibited protein and DNA synthesis in parallel but RNA synthesis to a lesser extent. Enhanced incorporation of tritiated thymidine was found when L cells were exposed to 0.4 to 0.016 ng of T-2 toxin ml-1 for 24 hours.