[Anti-inflammatory effect of Caragana microphylla Lam]

Caragana microphylla can antagonize the inflammation induced by carrageenin, hot water and croton oil. It can also inhibit the proliferation of granuloma, blood capillary permeability, phagocytic function of mononuclear phagocyte system, and synthesis or release of PGE2 at the inflamed part.

Crystal structure of insecticidal delta-endotoxin from Bacillus thuringiensis at 2.5 A resolution

The structure of the delta-endotoxin from Bacillus thuringiensis subsp. tenebrionis that is specifically toxic to Coleoptera insects (beetle toxin) has been determined at 2.5 A resolution. It comprises three domains which are, from the N- to C-termini, a seven-helix bundle, a three-sheet domain, and a beta sandwich. The core of the molecule encompassing all the domain interfaces is built from conserved sequence segments of the active delta-endotoxins. Therefore the structure represents the general fold of this family of insecticidal proteins. The bundle of long, hydrophobic and amphipathic helices is equipped for pore formation in the insect membrane, and regions of the three-sheet domain are probably responsible for receptor binding.

Dark adaptation of horizontal cells in the teleost fish retina

The dark adaptation behaviors of rod-driven and cone-driven horizontal cells were examined by analyzing their light responses recorded intracellularly in the intact, immobilized carp, and compared with that of the electroretinographic b-wave recorded simultaneously. Like the b-wave, the light responsiveness of rod horizontal cells increased gradually with time in the dark and attained a steady level at 60 min. On the other hand, cone horizontal cells initially increased in light responsiveness in the first 10 min, but thereafter decreased steadily so that the response amplitudes of these cells to bright light flashes were only 3-5 mV. The results suggest that cone horizontal cells are strongly suppressed in prolonged darkness.

Electroretinographic b-wave merely reflects the activity of the rod system in the dark-adapted carp retina

The electroretinogram and responses of intermediate horizontal cells (IHCs) were recorded simultaneously and studied under dark-adapted conditions in intact crucian carp, with the hope of providing an answer to the controversy whether the scotopic b-wave contains contribution from both rods and cones. Our observations indicate that the dark-adapted b-wave follows the univariance principle perfectly in that: (1) b-wave forms and shapes of response amplitude vs light intensity relationships did not depend on the stimulus wavelength; (2) response amplitudes to flashes of mixed wavelengths agreed exactly with the values predicted in accordance with the univariance principle. Furthermore, the spectral sensitivity of the b-wave matched well that of the IHC, receiving input exclusively from rods. In consequence, we conclude that the dark-adapted b-wave merely reflects the activity of the rod system, and the discrepancy between the spectral sensitivities of the b-wave and IHC response compared with the absorption spectrum of the rod photopigment may be due to the self-screening effect caused by the high optical density of porphyropsin in situ.

[A pattern-ERG study of amblyopia]

26 normal and 60 amblyopic children were examined with the P-ERG. The results showed that P-ERG in amblyopes was significantly abnormal, with delay in the latent periods of wave b and the after potential, as well as reduction in the amplitudes of the same. The latency of wave a was also delayed in some severe amblyopes. The abnormal manifestations of P-ERG and the mechanism in their occurrence were discussed. The P-ERG could be a sensitive and objective diagnostic method for amblyopia.

[Studies on stimulating circulation to end stasis in scleroderma]

Of 725 cases of scleroderma, 265 were of systemic type (the sex ratio being 1M:6F) and 460 of circumscribed type (the sex ratio being 1M:9F). The patients were divided into three groups and treated with three different stimulating circulation to end stasis (SCES) prescriptions. Satisfactory therapeutic effects were obtained in all. According to the clinical practice and laboratory findings, although SCES therapy exerted manifold actions on the disease, it not only softened the indurated connective tissues, tonified the body and improved the symptoms, but also improved laboratory indexes as follows: nailfold bed capillary, parameter of the peripheral blood stream in patients, content of urinary 2-ketol, 17-KS, free corten, serum joint-hexose, amino-hexose and histopathology including ultrastructure of the skin. The main effect was the improvement of circulation, especially the microcirculation and regulation of the metabolism of the connective tissues. Great attention should be paid to the drug's function of softening the indurated connected tissues. For further investigation, the authors have stressed three important points: screening of clinical symptoms and signs, examination of blood circulatory disturbances, and examination of pathological changes of the connective tissue. The necessity of developing new criteria for judging the therapeutic effects was emphasized.

Ammonia switch-off of nitrogenase from Rhodobacter sphaeroides and Methylosinus trichosporium: no evidence for Fe protein modification

In vivo switch-off of nitrogenase activity by NH4+ is a reversible process in Rhodobacter sphaeroides and Methylosinus trichosporium OB3b. The same pattern of switch-off in Rhodospirillum rubrum is explained by ADP-ribosylation of one of the Fe protein subunits, however, no evidence of covalent modification could be found in the subunits from either R. sphaeroides or M. trichosporium. Fe protein subunits from these organisms showed no variant behaviour on SDS-PAGE, nor were they 32P-labeled following switch-off. These observations suggest either that the attachment of the modifying group to the Fe protein in these organisms is quite labile and does not survive in vitro manipulation, or that the mechanism of switch-off is different than that seen in Rhodospirillum.

Changes in amino acid and nucleotide pools of Rhodospirillum rubrum during switch-off of nitrogenase activity initiated by NH4+ or darkness

Amino acid and nucleotide pools were measured in nitrogenase-containing Rhodospirillum rubrum cultures during NH4+- or dark-induced inactivation (switch-off) of the Fe protein. A big increase in the glutamine pool size preceded NH4+ switch-off of nitrogenase activity, but the glutamine pool remained unchanged during dark switch-off. Furthermore, methionine sulfoximine had no effect on the rate of dark switch-off, suggesting that glutamine plays no role in this process. In the absence of NH4+ azaserine, an inhibitor of glutamate synthate, raised glutamine pool levels sufficiently to initiate switch-off in vivo. While added NH4+ substantially increased the size of the nucleotide pools in N-limited cells, the kinetics of nucleotide synthesis were all similar and followed (rather than preceded) Fe protein inactivation. Darkness had little effect on nucleotide pool sizes. Glutamate pool sizes were also found to be important in NH4+ switch-off because of the role of this molecule as a glutamine precursor. Much of the diversity reported in the observations on NH4+ switch-off appears to be due to variations in glutamate pool sizes prior to the NH4+ shock. The nitrogen nutritional background is an important factor in determining whether darkness initiates nitrogenase switch-off; however, no link has yet been established between this and NH4+ (glutamine) switch-off.

Preliminary crystallographic studies on bacterioferritin from Azotobacter vinelandii

Bacterioferritin-cytochrome from Azotobacter vinelandii is an unusual protein containing haem groups as well as iron core like other ferritin. This paper reports the purification of bacterioferritin by affinity chromatography and the formation of brick-red crystals from a solution containing MgCl2. The crystals are optical isotropic with maximum dimensions of 0.4 X 0.4 X 0.1 mm3. The preliminary X-ray crystallographic studies have been performed. 1.5 degrees unscreened precession photographs show that the crystals of bacterioferritin belong to the cubic system, space group I432, with cell dimension 230 A. There are probably 8 molecules in one cubic unit cell and the molecule might have 32 symmetry. A molecular diameter of 115 A is derived from the packing of the molecules and a molecular weight of 826,000 is estimated for bacterioferritin.

Presence of a cytochrome b-containing ferritin in Azotobacter vinelandii

It has been demonstrated that a cytochrome b-containing ferritin is present in Azotobacter vinelandii. After DEAE cellulose chromatography and purification fractional precipitation by 50% of the saturated ammonium sulfate of the extract prepared from A. vinelandii cells, a hexagonal crystalline preparation is obtained. The protein contains 4--6% of nonheme iron. The protein molecule is made up of an electron dense iron core with a diameter of 70A and a protein shell with a diameter of 120A. The Fe core can be removed from the shell by the treatment with chelating and reducing agents. Electron micrographs and absorption spectra reveal that the protein shells are very similar before and after the removal of the core. The electrophoretic mobility and immunological properties of the Fe-free protein against the antibody of ferritin are very similar to those of the protein before the removal of the iron. From the above characteristics, it can be inferred that the protein belongs to ferritin. The protein part contains protoheme as prosthetic group and so it belongs to cytochrome b. Hence, the protein prepared from A. vinelandii is a kind of cytochrome b-containing ferritins. The possible role of the ferritin in biological nitrogen fixation is discussed in this paper.