V/Q SPECT imaging of acute pulmonary embolus - a practical perspective.

The following article is intended to illustrate the place of scintigraphy and computed tomography pulmonary angiography (CTPA) in the investigation of acute PE in current practice, and to guide non-radionuclide radiologists and other medical professionals to the best test for patients. We share our early experiences with ventilation-perfusion (V/Q) single-photon-emission computed tomography (SPECT) including image acquisition and interpretation. A comparison of the two techniques is given, along with practical considerations in a variety of clinical scenarios.

Anti-AIDS agents, 3. Inhibitory effects of colchicine derivatives on HIV replication in H9 lymphocyte cells.

A series of colchicine and isocolchicine derivatives were evaluated as inhibitors of HIV replication in H9 lymphocytes. Colchicine showed only very slight inhibition in the absence of toxicity, as measured by the therapeutic index (IC50/EC50). None of the derivatives inhibited HIV replication in the absence of toxicity.

Cadmium and zinc flux in wild-type and cadmium-resistant CHO cells.

Cellular flux of cadmium-109 and zinc-65 is characterized in cultured Chinese hamster ovary cells. The transport of cadmium is primarily unidirectional and, following uptake, cadmium is strongly retained. Zinc transport is bidirectional and intracellular zinc continuously leaches out into the medium. Nonradioactive cadmium or zinc enhances the efflux of(65)Zn from prelabeled cells. Transport of these metals into wild-type cells is not affected by azide, ouabain, cycloheximide, or actinomycin D. A cadmium-resistant mutant was isolated that exhibited altered sensitivities to certain inhibitors of macromolecular synthesis as well as quantitative differences in metal transport and accumulation. Although the mutant accumulates less cadmium than the wild-type cell, that which is retained is bound much more tightly. In addition, this lower rate of cadmium uptake is significantly decreased by either cycloheximide or actinomycin D. This suggests that thede novo synthesis of a protein or proteins is required for much of the net cadmium retention by the cadmium-resistant cells.

A BASIC microcomputer program for plotting the secondary structure of proteins.

An Applesoft BASIC program is presented which allows one to readily graph the secondary structure of a protein on the basis of information derived from its amino acid sequence. This applies the Chou/Fasman rules of predictions to the alpha-helix, beta-sheet and coil conformational parameters. The program produces a first approximation and provides the additional feature which permits specific modification in the plotted structure. These modifications produce a plot comparable to the existing data obtained from X-ray crystallography and manual computations.

Cellular uptake of cadmium and zinc.

CHO mutants, resistant to over 100-fold of a normally toxic level of extracellular cadmium have been used to examine the mutually antagonistic effect of Cd and Zn on their uptake. Cadmium uptake in these mutants is only 7-10% that of the parental cells. Zinc uptake in these mutants is equal to or greater than that in the wild-type cells. Results of kinetic studies on uptake indicated that the two metals interact by competitive inhibition. TheK m andK i values for Cd and/or Zn were different in some of the mutants and indicate multiple carriers may be involved in the transport of these metals. The reduction in Cd uptake and concomitant increase in Zn uptake contribute to the increased Cd resistance in these mutants.

Nature of the fructan of Streptococcus mutans OMZ 176.

The fructan of Streptococcus mutans OMZ 176 was shown to have a levan structure by comparing the chromatographic mobilities of the saccharides produced by partial acid hydrolysis of ghe fructan and known levan and inulin. This was confirmed by using concanavalin A as a lectin in a double-diffusion gel technique.