Ultrasonography in preclinical education: a pilot study.

Context: Ultrasonography is a valuable diagnostic tool in the clinical setting. Yet, medical students often have minimal familiarity with this technology.

Objective: To evaluate the ability of second-year medical students to use ultrasonography for identification of anatomic structures and pathologic conditions.

Roles of the ccoGHIS gene products in the biogenesis of the cbb(3)-type cytochrome c oxidase.

In many bacteria the ccoGHIS cluster, located immediately downstream of the structural genes (ccoNOQP) of cytochrome cbb(3) oxidase, is required for the biogenesis of this enzyme. Genetic analysis of ccoGHIS in Rhodobacter capsulatus demonstrated that ccoG, ccoH, ccoI and ccoS are expressed independently of each other, and do not form a simple operon. Absence of CcoG, which has putative (4Fe-4S) cluster binding motifs, does not significantly affect cytochrome cbb(3) oxidase activity.

Glutamate-89 in subunit II of cytochrome bo3 from Escherichia coli is required for the function of the heme-copper oxidase.

Recent electrostatics calculations on the cytochrome c oxidase from Paracoccus denitrificans revealed an unexpected coupling between the redox state of the heme-copper center and the state of protonation of a glutamic acid (E78II) that is 25 A away in subunit II of the oxidase. Examination of more than 300 sequences of the homologous subunit in other heme-copper oxidases shows that this residue is virtually totally conserved and is in a cluster of very highly conserved residues at the "negative" end (bacterial cytoplasm or mitochondrial matrix) of the second transmembrane helix. The functional importance of several residues in this cluster (E89II, W93II, T94II, and P96II) was examined by site-directed mutagenesis of the corresponding region of the cytochrome bo(3) quinol oxidase from Escherichia coli (where E89II is the equivalent of residue E78II of the P.

Cu XAS shows a change in the ligation of CuB upon reduction of cytochrome bo3 from Escherichia coli.

Copper X-ray absorption spectroscopy (XAS) has been used to examine the structures of the Cu(II) and Cu(I) forms of the cytochrome bo3 quinol oxidase from Escherichia coli. Cytochrome bo3 is a member of the superfamily of heme-copper respiratory oxidases. Of particular interest is the fact that these enzymes function as redox-linked proton pumps, resulting in the net translocation of one H+ per electron across the membrane.

FT-IR analysis of membranes of Rhodobacter sphaeroides 2.4.3 grown under microaerobic and denitrifying conditions.

Fourier transform infrared spectroscopic analysis of CO binding proteins in Rhodobacter sphaeroides reveals the presence of a membrane-bound nitric oxide reductase (Nor). Nor has been clearly distinguished from the cytochrome oxidases by the temperature-dependence of relaxation following photodissociation of the CO complex at cryogenic temperatures. The center frequency and band shape, 1970 cm-1 and 20-30 cm-1 width at half-peak height, are similar to those reported for resonance Raman spectra of purified Paracoccus denitrificans Nor.