Oxygen concentration-dependent induction of a 140-kDa protein in magnetic bacterium Magnetospirillum magnetotacticum MS-1

Abstract The magnetic bacterium Magnetospirillum magnetotacticum prefers a microaerobic habitat and should be able to sense oxygen. Therefore, the bacterium was cultured under atmospheres containing 0–5% O₂ and analyzed for oxygen-dependent changes in the levels of its protein components by sodium dodecyl sulfate-polyccrylamide gel electrophoresis (SDS-PAGE). The analysis revealed a marked anaerobic induction of a 140-kDa protein, which was suppressed when M. magnetotacticum was switched from microaerobic (<1% O₂) to aerobic (>1% O₂) growth conditions. Although its function remains to be determined, the 140-kDa protein may serve as a useful tool to gain insight into the physiology of the organism.     

Response of isolated rat iris dilator to adrenergic and cholinergic agents and electrical stimulation

Responses of isolated rat iris dilator to some agents and to electrical stimulation were examined. Norepinephrine and epinephrine produced contraction, which was antagonized by 0.03 μM phentolamine. Acetylcholine produced relaxation at low concentrations (1 nM ? 1 μM) as great as 80 % of the resting tone while contraction at high concentrations (≥1 μM). Both responses were suppressed by 0.02 μM atropine and enhanced by 0.03 μM physostigmine. Electrical stimulation at low voltage or low frequency (up to 10 Hz) elicited relaxation while stimulation at high voltage or high frequency (30 Hz) produced contraction. Stimulation with intermediate strength elicited biphasic response. The contraction and relaxation induced by electrical stimulation were abolished by 3 μM phentolamine or by 0.05 μM atropine, respectively. Both phases were abolished by tetrodotoxin (0.3 μM). It is suggested that in the rat the cholinergic relaxation of the dilator may assist the cholinergic contraction of the sphincter (1). The pronounced cholinergic relaxation of nonvascular tissue is to be noted.     

2-Ketogluconate Reductase Inhibition by Oxalate

The active site of α-glucosidase from Mucor javanicus IFO 4570 was investigated by kinetic studies. Competition between maltose and soluble starch, and linearity of Lineweaver-Burk plots for the mixed substrates were observed. The dependence of the apparent maximum velocities agreed with those predicted for a single active site mechanism. These results suggest that the enzyme hydrolyzes maltose and soluble starch at a single active site.     

Studies on the Protection Test of Pertussis Vaccine. Immunization Period and Protectivity

In order to confirm the data reported in the previous papers, variously prepared pertussis vaccines were employed in the present investigation. Pertussis organisms grown either on a solid or in a liquid semisynthetic medium were treated by: (1) heating at 56 C for 30 min, (2) storage in 0.1% formalin at 37 C for 5 days, (3) storage in 0.1% formalin at 25 C for 5 days, and (4) simple addition of sodium ethyl-mercuri thiosalicylate (merthiolate) as a preservative. Freeze-dried vaccines were made from these preparations four and a half months later. Mice were immunized intraperitoneally and challenged intracerebrally with a virulent strain of Bordetella pertussis 10 or 17 days later. The data were analyzed statistically assuming the probit corresponding to the percentage of survivors at any dose be a linear function of the logarithms of the dose. The 50% effective doses (ED₅₀) and slopes of each vaccine were found to be uniform. More accurate estimates of ED₅₀ were obtained by employing a pooled slope in each experiment. From these ED₅₀ values, the relative potency was estimated by comparing the value of a vaccine to that of a dried merthiolate-vaccine. For vaccines derived from solid cultures, with an immunization period of 17 days, the relative potency of the vaccine heated at 56 C was 0.63 (95% fiducial limits=0.52 to 0.76); the value for the formalinized vaccine at 37 C was 0.40 (0.30 to 0.53) and one at 25 C was 0.51 (0.34 to 0.77). Vaccines derived from liquid cultures showed a relative potency of 20 to 50% less than that of corresponding vaccine derived from a solid culture. The potency obtained for the 17 day immunization period was usually higher than that for the 10 day period. Using the overall-pooled slope, an experimental design which will be appropriate for statistical analysis is discussed.     

Human platelet aggregation induced by prostaglandin endodisulfide

The effect of human platelet functions of 9,11-dithio analogues of prostaglandin endoperoxide was investigated. Methyl (5z,9α,11α,13e,15S)-9,11-epidithio-15-hydroxyprosta- 5,13-dienoate induced platelet aggregation, while the 9β,11β-epimer was inactive. The platelet aggregation caused by the 9α,11α-dithio analogue was associated with serotonin release from platelets, and was inhibited by methyl ester of prostaglandin I₂ (prostacyclin) but not by indomethacin.     

The Purification of Amyloid Fibril Proteins

Amyloid fibril concentrates have been fractionated and shown to have homogeneous fragments of the variable region of immunoglobulin proteins as their major protein constituent. Amyloid fibril protein purification was performed on ten amyloid preparations by sequential gel filtration on Sepharose 4 B and Sephadex G-100 columns equilibrated with 5 M guanidine-HCl in 1 N acetic acid.     

New Neplanocin Analogues. V. A Potent Adenosylhomocysteine Hydrolase Inhibitor Lacking Antiviral Activity. Synthesis And Antiviral Activity Of 6″-Carboxylic Acid Derivatives Of Neplanocin A 1

Abstract

The 6′-carboxylic acid derivative of neplanocin A 3 was synthesized from NPA, and was converted to the corresponding methyl ester 4 and amides 5 and 6. These were evaluated for their anti-RNA-virus activities. Of the derivatives synthesized, only 5 was active against RNA viruses within the concentration range of 0.14-4.88 μg/mL. Compounds 3 and 5 showed a potent inhibitory effect on S-adenosylhomocysteine (AdoHcy) hydrolase from rabbit erythrocytes. Although a close correlation between the inhibitory effect of adenosine analogues on AdoHcy hydrolase and their antiviral potency has been demonstrated, 3 did not show any anti-RNA-virus activities.