Biomedical subjects
Publications and source records attributed to H Ono.
Thiotropocin, a new sulfur-containing 7-membered-ring antibiotic, was isolated from a culture broth of Pseudomonas sp. CB-104. The antibiotic occurs as orange or yellowish orange needles and has the molecular formula C8H4O3S2. It is active against Gram-positive and Gram-negative bacteria, some phytopathogens and mycoplasma.
Three Gram-negative bacteria produce new cephem antibiotics, named cephabacins, with unique 3-side chains. Cephabacins include F group antibiotics with a 7-formylamino substituent and H group antibiotics without the substituent. The producing bacteria were taxonomically characterized and designated as Lysobacter lactamgenus sp. nov. YK-90 and Xanthomonas lactamgena sp. nov. YK-278 and YK-280.
Fifteen components of new antibiotics, cephabacins, were isolated from the culture filtrates of Lysobacter lactamgenus YK-90, Xanthomonas lactamgena YK-280 and X. lactamgena YK-278. They were purified by column chromatography using cation-exchange resins, activated carbon, high porous resins and cation-exchange Sephadex and by preparative reverse-phase HPLC. The basic, water-soluble antibiotics were characterized as having a cephem skeleton and oligopeptide(s) as a side chain constituent from their spectroscopic analyses and amino acid analyses.
Cephabacin F group antibiotics with a 7-formylamino substituent showed antibacterial activity against a wide variety of bacteria including beta-lactamase-producing clinical isolates and anaerobic bacteria. Cephabacin H group antibiotics without the substituent showed more potent activity against Gram-positive bacteria than cephabacin F group antibiotics, but were not active against Gram-negative bacteria producing beta-lactamases. Cephabacin F group antibiotics were highly resistant to hydrolysis by various types of beta-lactamases and showed strong inhibitory activity against a cephalosporinase of Proteus vulgalis GN 4413 due to the 7-formylamino substituent. Mode of action of cephabacin F1 and H1 was examined using Escherichia coli and Bacillus subtilis as the test organisms. They showed strong lytic activity against these organisms and inhibited their peptidoglycan synthesis. Cephabacin F1 had the highest affinity for penicillin-binding protein (PBP) 1 in E. coli and PBP 4 in B. subtilis. Cephabacins showed a protective effect in experimentally infected mice.
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Aflatoxin B1 (AFB1) was detected in serum samples of healthy Japanese males by radioimmunoassay and high-performance liquid chromatography. Blood samples were obtained from 20 subjects after fasting and from 80 subjects after lunch. The subjects ranged in age from 20 to 63 years of age. Measurement of AFB1 in the samples was performed by radioimmunoassay and was confirmed by high-performance liquid chromatography using a mu Porasil column and a C18-mu Bondapak column after the conversion of AFB1 to its water adduct AFB2a. AFB1 was detected in 5 of 20 fasting blood samples [20 to 56 pg/ml of serum; 33.6 +/- 14.6 (S.D.)] and in 29 of 80 serum samples taken after lunch (20 to 1169 pg/ml of serum; 218.1 +/- 268.3). Mass spectral analysis of the material obtained after high-performance liquid chromatography separation from serum samples confirmed the presence of AFB1.
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Bovine follicular oocytes cultured in vitro in Ham's F-12 based medium for 27 hours were transferred to the oviducts of rabbits pretreated with 75 IU hCG 24 hours previously. Frozen-thawed bull spermatozoa were inseminated into the uterus of rabbits 0, 2, 4, 6, 9, and 12 hours before oocyte transfer. Fertilization and cleavage were examined in the oocytes recovered from the oviduct and uterus 24 and 48 hours later. The criteria of fertilization were the presence of an enlarged sperm head, sperm tail, and pronuclei in the vitellus. Bull spermatozoa inseminated 4 hours before oocyte transfer showed the highest rates of fertilization at both 24 and 48 hours (35% and 38%) compared to the other preincubation times. The numbers of cleaved oocytes were also greater at these times. The results indicate that the capacitation time of cryopreserved bull spermatozoa in the rabbit reproductive tract is the same as in the bovine tract--i.e., 4-6 hours.
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In the isolated frog spinal cord perfused with kainic acid (KA, 5 X 10(-4) M) containing Ringer's solution, within 2 hr there were increases in the amplitude of the dorsal root depolarization, as induced by the GABA-agonists. KA perfusion produced increases in the specific binding of [3H]muscimol to crude synaptic membranes and incubation with KA for 3 hr did not increase [3H]muscimol binding. [3H]GABA was released from KA-treated spinal cord slices in the presence of high K+. KA-induced supersensitivity of the dorsal root to GABA may relate to direct actions on primary afferent terminals and not to denervation of GABAergic neurons.
This experiment showed that phoria-induced displacement adds to or subtracts from prism-induced displacement. A near stimulus (25 cm) was apparently displaced more than the optical displacement when the base of a prism was out and less when the base was in. In contrast, a far stimulus (200 cm) was displaced less when the base was out and more when the base was in. Moreover, the between-subjects variability of the apparent displacement was greater with monocular than with binocular viewing. Some implications for studies on monocular prism adaptation are discussed.
The expansion and contraction of a display consisting of a stationary grating with a superimposed inclined line leads to the apparent rotation of the line. This phenomenon has been investigated in six experiments with the use of a television system with a motorized zoom lens to effect such transformations. The maximum apparent line rotation occurs with the line at 45 degrees to the grating. In experiment 1 a greater magnitude of apparent rotation was found with a vertical grating and an oblique line than vice versa. Zoom-out (contraction) also produced greater rotation than zoom-in (expansion). The orientation anisotropy was not dependent upon the orientation of the display to the retinal meridian (experiment 2): the extent of apparent line rotation was approximately the same with a vertical grating when the head was upright or tilted so that the retinal meridian was at 45 degrees. At a constant rate of zooming, a zoom duration of 2 s produced a larger apparent line rotation than one of 1 s, but it was not influenced by the initial angular subtense of the superimposed line (experiment 3). Neither the spatial frequency of the grating nor the width of the line affected the apparent rotation (experiments 4, 5, and 6). Experiment 5 compared the apparent rotation when the display was zoomed (i) with a fixed surround and (ii) with a surround that also expanded during zooming. The magnitude of rotation in the latter condition was reduced to about 25% of that with a fixed surround. The results are discussed in terms of the discrepancy between the perceived transformations of the background grating and the superimposed line.
Streptomyces glaucescens strain GLAO (=ETH 22794) produces hydroxystreptomycin and has a high natural resistance to hydroxystreptomycin, dihydrostreptomycin and streptomycin. The wild-type strain gives rise spontaneously to streptomycin-sensitive (StrS-) variants at a frequency of 0 . 2 to 1 . 4%. These mutants lack streptomycin phosphotransferase activity responsible for the wild-type resistance to streptomycin group antibiotics and are unable to produce detectable amounts of hydroxystreptomycin. Mapping experiments showed that the strS marker lies between the chromosomal markers lys-2 and ura-3 on the linkage map of S. glaucescens. The molecular basis for instability of this marker is as yet unknown.
The wild-type strain of Streptomyces glaucescens produces hydroxystreptomycin and shows an inherent natural resistance to streptomycin group aminoglycoside antibiotics. Cell free extracts of the wild-type strain were able to inactivate streptomycin, hydroxystreptomycin and dihydrostreptomycin in the presence of ATP. The phosphotransferase did not inactivate other aminoglycoside antibiotics, including spectinomycin. Mutant strains were isolated, which were highly sensitive to streptomycin group aminoglycosides, had no measurable phosphotransferase activity and were unable to form detectable amounts of hydroxystreptomycin. This suggests either a correlation between phosphotransferase activity, streptomycin resistance and hydroxystreptomycin formation or defects in more than one gene in the strS mutant strains tested.
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Although extracranial-intracranial (EC-IC) artery anastomosis seems to result in symptomatic improvement in certain types of cerebrovascular ischemic disease, this procedure can also be associated with significant morbidity, some of which paradoxically may be the direct result of a patent bypass. A review of the last 51/2 years at the Oregon Health Sciences University shows that 50 patients underwent 51 superficial temporal artery to middle cerebral artery bypass procedures with an angiographic patency rate of 91%. Of the 50 patients, 17 had intracranial stenotic lesions of either the middle cerebral artery (7 patients) or the internal carotid artery (10 patients). One patient had posterior cerebral artery stenosis. Five of the 18 patients with stenosis and a patent bypass developed a symptomatic occlusion of the stenotic lesion within 30 days after the anastomosis. It is hypothesized that the EC-IC bypass may have contributed to the occlusion in some of these patients by causing a change in the hemodynamic state. Possibly the bypass reversed the direction of flow distal to the stenosis to result in stasis and subsequent occlusion at the site of the stenosis or in some other manner affected hemostasis (i.e., the coagulation cascade).
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Whether or not zopiclone, a new sleep-inducing drug, exerted a similar effect to that of benzodiazepines was examined. The drug inhibited crossed extensor reflexes in chicks and augmented the dorsal root-dorsal root reflexes in rats without affecting the mono- and polysynaptic reflexes. The site of its action was considered to be located in the spinal cord since the effect on the dorsal root reflex was observed also in the spinal rats. Zopiclone selectively reduced the phasic responses of anemic decerebrate rigidity like benzodiazepines in rats. Despite the structural difference from the benzodiazepines, zopiclone dose-dependently inhibited [3H]flunitrazepam binding in rat brain membranes, although the potency was weaker. These results suggested that zopiclone exerts CNS actions via benzodiazepine receptors.