Specific interactions between aryl hydrocarbon receptor and dioxin congeners: ab initio fragment molecular orbital calculations.

Aryl hydrocarbon receptor (AhR) is a transcription factor and its function is activated by the binding of halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 1,2,4-trichlorodibenzo-p-dioxin (TrCDD). TCDD is highly toxic to rat, whereas its congener TrCDD shows only a weak effect on gene expression. In order to elucidate the reason of this remarkable difference in the effect of TCDD and TrCDD, we here obtained stable structures of the complexes with rat AhR (rAhR) and TCDD/TrCDD and investigated their electronic properties by using the ab initio fragment molecular orbital (FMO) method.

Spontaneous osteonecrosis of the lateral femoral condyle of the knee: a report of 11 cases.

Background: Spontaneous osteonecrosis (SON) of the lateral femoral condyle of the knee joint is very rare and there have been only a few articles about this condition.

Materials: We reviewed data for 11 patients (7 men, 4 women) with unusual SON of the lateral femoral condyle of the knee. The average age of patients at onset was 61.

Identification of a high-affinity binding site for dinotefuran in the nerve cord of the American cockroach.

The binding of the neonicotinoid insecticide dinotefuran to insect nicotinic acetylcholine receptors (nAChRs) was examined by a centrifugation method using the nerve cord membranes of American cockroaches and [3H]dinotefuran (78 Ci mmol-1). The Kd and Bmax values of [3H]dinotefuran binding were estimated to be 13.7 nM and 14.