Bronchoscopy of the horse.

The endobronchial anatomy of 12 lung specimens from horses and 12 healthy, standing, sedated horses was evaluated, using a 200-cm-long, 9.5-mm-diameter videoendoscope. On the basis of these findings, the nomenclature system of Amis and McKiernan was modified for identification of airways of horses during bronchoscopy. Lobar bronchi are identified on the basis of the side of the bronchial tree on which they were found and the order in which they originated from the primary bronchus. Thus, RB1, RB2, and RB3 referred to right cranial lobar bronchus, respectively. On the left side, the designation of LB1 and LB2 refer to the left cranial lobar bronchus and the left caudal lobar bronchus, respectively. Segmental bronchi are identified by consecutive numbers in the order of origination from the lobar bronchus. The direction of the segmental bronchus was denoted by the capital letter D (dorsal), V (ventral), L (lateral), M (medial), R (rostral), and C (caudal). Subsegmental bronchi were identified in the order of origination from the segmental bronchi, using lower case letters (eg, RB2, 1V, a or RB2, 1V, aV). For subsequent branching of the subsegmental bronchi, the branches were numbered consecutively by their order of origination (eg, RB2, 1V, aV, 1D).

Clinical use of metronidazole in horses: 200 cases (1984-1989).

Case records of 200 horses treated with metronidazole were reviewed. Horses were treated for respiratory tract infections (90 cases), peritonitis or abdominal abscess (39 cases), celiotomy (49 cases), orthopedic infections (6 cases), and miscellaneous soft tissue infections (16 cases). Bacteria of the genus Bacteroides were most prevalent (55 of 167 anaerobic isolates). Metronidazole was always used in combination with other antimicrobial drugs. Only 4 of the 200 horses had signs of adverse effects associated with metronidazole treatment. Those 4 horses had poor appetite that resolved when metronidazole treatment was discontinued.

Synthetic analogs of the active sites of iron-sulfur proteins. Structure and properties of bis(o-xylyldithiolato-m2-sulfidoferrate (3)), an analog of the 2Fe-2S proteins.

The synthetic analog approach has been applied to a clarification of the active sites of 2Fe-2S(*) proteins. The compound (Et(4)N)(2)[FeS(SCH(2))(2)C(6)H(4)](2), derived from o-xylyl-alpha,alpha'-dithiol, has been prepared and its structure has been determined by x-ray diffraction. The centrosymmetric anion contains two tetrahedrally coordinated ferric ions bridged by two sulfide ions and separated by 2.70 A. Comparison of electronic, Mössbauer, and proton magnetic resonance spectra and magnetic susceptibility of the anion with the corresponding properties of the oxidized forms of the proteins reveals significant degrees of similarity. The anion also exhibits the essential redox capacity of the proteins. We conclude that [FeS(SCH(2))(2)C(6)H(4)](2) (2-) possesses the same total oxidation level and electronic configuration as the active sites of the oxidized proteins, and that its structure provides a feasible representation of the minimal structure of the active site. [FeS(SCH(2))(2)C(6)H(4)](2) (2-) is thus the first well-defined synthetic analog of the active sites of two-iron ferredoxins.

Structure and properties of a synthetic analogue of bacterial iron--sulfur proteins.

The compound (Et(4)N)(2)[Fe(4)S(4)(SCH(2)Ph)(4)] has been prepared and its structure determined by x-ray diffraction. The Fe(4)S(4) core of the anion possesses a configuration of D(2d) symmetry that is closely related to the Fe(4)S(4) active-site structures of the high-potential iron protein from Chromatium and the ferredoxin from Micrococcus aerogenes. Electronic properties of the tetrameric anion have been partially characterized by measurement of proton magnetic resonance, Mössbauer, photoelectron, and electronic spectra, and magnetic susceptibility. Comparison of corresponding properties of [Fe(4)S(4)(SCH(2)Ph)(4)](2-) and the proteins implies that the oxidation levels of the synthetic tetramer, the reduced form of the high-potential protein, and the oxidized form of the 8-Fe ferredoxins are equivalent. The tetramer possesses the one-electron redox capacity associated with the 4-Fe centers of the ferredoxins. The structural and collective electronic features of [Fe(4)S(4)(SCH(2)Ph)(4)](2-) reveal it to be the first well-defined synthetic analogue of the active site of an iron-sulfur protein.