X-ray equatorial diffraction studies on the cross-sectional structure of Salmonella flagella

X-ray diffraction studies have been made on the cross-sectional structure of the normal Salmonella flagella. Two approaches have been made: one based upon small-angle equatorial scatterings (2θ 3°) and the other upon moderate-angle angle equatorial diffractions (3° 2θ 10°).Analysis of small-angle scattering data gives the radius of gyration of the flagella as 68 Å. Cylindrically averaged electron density of the cross-section of the flagella is obtained by means of the Fourier-Bessel transformation method. The average radius of the flagella is about 65 Å.In the investigation of the moderate-angle diffraction pattern, validity is examined of the model that a flagellum consits annularly arranged strands, of which each has a cylindrically symmetric structure. Features of the pattern observed in the range of 3° < 2θ < 10° can be interpreted fairly well by this model. Average radii of the flagella obtained for the 11 and 13 strands models are close to that obtained by the analysis of the small-angle scattering data.     

Amino acid uptake in the peripheral nerve of the rat

When rat sciatic nerves were incubated with C¹⁴l-lysine, l- or d-glutamate, or d-l γ-aminoisobutyrate, the labeled compounds penetrated the nerve, and the level of lysine and leucine after 1 hr was higher in the nerve than in the medium. The level increased with time, and at 24 hr glutamate levels also were higher in the nerve than in the medium. Lowering the temperature strongly inhibited uptake, while other conditions such as absence of glucose, absence of sodium, or the presence of cyanide inhibited uptake by nerve less than uptake by brain slices. The uptake against a concentration gradient, and inhibitions of this uptake by metabolic inhibitors and by structural analogs, were interpreted as showing the presence of transport processes for amino acids in peripheral nerves with characteristics similar to such transport processes in the central nervous system.     

Stain Technology: A Simplified Aluminum Stain in Paraffin Sections of Bone from Hemodialysis Patients

A new simplified method has been devised for staining aluminum and has been tested in paraffin sections of bone from 60 patients who have undergone hemodialysis. Iliac crest bone fragments were fixed in 20% phosphate-buffered formalin for less than a day and demineralized at room temperature in 10% phosphate-buffered formalin containing 5% formic acid for only 2 to 3 hr. Four-micron paraffin sections, accompanied by positive controls, were stained with Maloney's aluminum stain, the Berlin blue reaction for iron, dylon or Congo red for amyloid and von Kossa's reaction for calcium. Aluminum and iron were demonstrated particularly at the mineralizing front of bony tissues; aluminum in 52 cases, iron in 45. Dylon staining also gave positive results in 52 cases. It is important in determining whether aluminum deposition is present that the von Kossa reaction remains positive even after demineralization. This method may be more useful for demonstrating aluminum in bony tissues than the complicated and time-consuming resin-embedding method currently used.     

Prostacyclin contributes to inhibition of hypoxic pulmonary vasoconstriction by alkalosis

The mechanism by which extracellular alkalosis inhibits hypoxic pulmonary vasoconstriction is unknown. We investigated whether the inhibition was due to intrapulmonary production of a vasodilator prostaglandin such as prostacyclin (PGI₂). Hypoxic vasoconstriction in isolated salt-solution-perfused rat lungs was blunted by both hypocapnic and NaHCO₃_induced alkalosis (perfusate pH increased from 7.3 to 7.7). The NaHCO₃-induced alkalosis was accompanied by a significant increase in the perfusate level of 6-keto-prostaglandin F_1α (6-keto-PGF_1α), an hydrolysis product of PGI₁. Meclofenamate, an inhibitor of cyclooxygenase, counteracted both the blunting of hypoxic vasoconstriction and the increased level of 6-keto-PGF_1α. In intact anesthetized dogs, hypocapnic alkalosis (blood pH increased from 7.4 to 7.5) blunted hypoxic pulmonary vasoconstriction before but not after administration of meclofenamate. In separate cultures of bovine pulmonary artery endothelial and smooth muscle cells stimulated by bradykinin, the incubation medium levels of 6-keto-PGF_1α were increased by both hypocapnia and NaHCO₃-induced alkalosis (medium pH increased from 7.4 to 7.7). These results suggest that inhibition of hypoxic pulmonary vasoconstriction by alkalosis is mediated at least partly by PGI_2.