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Biomedical subjects

K Ochi

Publications and source records attributed to K Ochi.

At least 199 records · Page 11Linked to original sources
PubMed1983

Specificity and control of uptake of purines and other compounds in Bacillus subtilis.

Certain nucleotides control adaptation to changing nutrition or differentiation (sporulation) resulting from a general nutritional deficiency. To maintain the adaptation or differentiation process, once it has started, it may have been important for cells to evolve several independent and metabolically controllable systems enabling the uptake and metabolism of various nucleic acid bases or nucleosides. We have analyzed the cellular reactions with these compounds by measuring both their effect on growth and their uptake in appropriately chosen auxotrophic and uptake mutants. We have found one uptake system for guanine and hypoxanthine, another one for guanosine and inosine, and three other systems for adenine, adenosine, and uracil. The uptake systems of guanine-hypoxanthine and guanosine-inosine are inhibited by the stringent response to amino acid deprivation (increase of guanosine 5'-diphosphate-3'-diphosphate), but they do not depend on the concentration of GTP, which decreases during sporulation. In contrast, the uptake of Ura depends on the presence of GTP, regardless of whether a GTP decrease was produced by the stringent response or otherwise. This was the only uptake system whose decrease was always correlated with the onset of sporulation. The uptake of other compounds, e.g., alpha-methylglucoside and alpha-aminoisobutyric acid, decreased under some, but not all, sporulation conditions.

Adenine↗
PubMed1983

Effect of 24-hour ureteral obstruction on subsequent ischemic damage in rat kidney.

The effects of prior 24-hour ureteral obstruction on ischemic renal damage were studied in rats. Rats were divided into 6 groups with different times of ischemia (0, 60 and 90 min) and with or without 24-hour ureteral obstruction. Following a 4-week recovery period, contralateral nephrectomy was performed and the rat was sacrificed 24 h later for the determination of serum creatinine and for histologic examination of the affected kidney. A preceding ureteral obstruction for 24 h made no difference to the renal damage with 60 min of ischemia or without ischemia. However, kidneys with 90 min of ischemia and 24 h of ureteral obstruction were more damaged than those with 90 min of ischemia only. These results suggested that the hydronephrotic kidney was more susceptible to long periods of ischemia than the normal kidney.

Animals↗
PubMed1983

Individual renal function study using computed tomography.

Using computed tomography, the renal parenchymal volume and tissue-plasma ratio of contrast enhancement, with a bolus injection, were measured, and the latter measurement is believed to indicate regional renal function per unit of parenchymal volume. 67 studies were carried out on 50 patients, 17 of whom were examined pre- and postoperatively. Of these 50 patients, 27 had hydronephrosis, 6 had renovascular disease, 4 had pyelonephritis and the remaining 13 were control patients. The product of tissue-plasma ratio of contrast enhancement and the calculated renal parenchymal volume were found to be in good correlation with the individual renal function measured with 99mTc-dimercaptosuccinic acid and 131I-hippuran. Since this method is reproducible, the kidney being examined may be seen in more detail.

Creatinine↗
PubMed1983

Histochemical studies on enzyme-digested protein plugs of patients with chronic pancreatitis: a preliminary report.

Sulfated acidic mucopolysaccharides have been found to be significant components of "protein plugs" in patients with chronic pancreatitis. The precise identification of the mucopolysaccharides and their distribution within the protein plugs may clarify the pathogenesis of the plugs. Pure pancreatic juice from five patients with chronic pancreatitis was obtained by endoscopic retrograde catheterization of the papilla of Vater. Enzymes for digestion of the plugs included hyaluronidase of the bovine testes and streptomyces hyalurolyticus, chondroitinase ABC and AC, and sialidase (neuraminidase). Our study indicated that: I) Sialic acid is distributed throughout the plugs and may be a major component, followed by a lesser amount of chondroitin sulfate B. 2) Chondroitin sulfate A, C, D and E and chondroitin may be minor components. 3) Hyaluronic acid is negligible in the plugs.

Chronic Disease↗
PubMed1982

Arachidonate 12-lipoxygenase of porcine leukocyte with activity for 5-hydroxyeicosatetraenoic acid.

When arachidonic acid was incubated with porcine polymorphonuclear leukocytes, 12-hydroxy-5,8,10,14-eicosatetraenoic acid was produced as a major product. The production of this compound was not accounted for by contaminating platelets known to contain arachidonate 12-lipoxygenase. The enzyme was found predominantly in a cytosol fraction of leukocytes, and the cytosolic enzyme was purified about 30-fold by ammonium sulfate fractionation and DEAE-Sephadex column chromatography. The partially purified enzyme transformed arachidonic acid to a compound which was identified as 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid. 5-Hydroxy-6,8,11,14-eicosatetraenoic acid as substrate was about 40% as active as arachidonic acid, and the reaction was inhibited by the addition of arachidonic acid. The reaction product which was further reduced by sodium borohydride was indistinguishable from authentic 5S, 12S-dihydroxy-(E,Z,E,Z)-6,8,10,14-eicosatetraenoic acid.

Animals↗
PubMed1982

2,3,5-Trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861), a selective inhibitor of the 5-lipoxygenase reaction and the biosynthesis of slow-reacting substance of anaphylaxis.

2,3,5-Trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861) inhibited 5-lipoxygenase of guinea pig peritoneal polymorphonuclear leukocytes (ID50, 0.8 microM). The inhibition was of competitive type. 12-Lipoxygenases and fatty acid cyclooxygenase were not affected below 10 microM. The formation of slow-reacting substance of anaphylaxis by the sensitized guinea pig lung was almost fully suppressed by the compound at 10 microM.

Animals↗
PubMed1982

Computerized tomography of the kidney: tissue-plasma ratio of contrast enhancement with bolus injection and renal function.

Computerized tomography can be used not only for morphological studies but for physiological ones as well. Using computerized tomography, we were able to observe changes in renal parenchymal flow rates, with the aorta and renal parenchyma as regions of interest. There were 62 studies performed on 48 patients with and without known renal disease. The change in the tissue-plasma ratio with the use of contrast medium in 124 renal units correlated well with the renal function observed on excretory urography. The 14 patients subjected to renal ischemia during surgery underwent computerized tomography before and after the operation. The change in the tissue-plasma ratio of those kidneys operated upon was decreased significantly postoperatively compared to values found for the nonischemic contralateral kidneys. The results were reproducible and suggest that computerized tomography can be used as a method of evaluating the renal function per unit of parenchymal volume.

Contrast Media↗
PubMed1982

Measurement of renal parenchymal volume using computed tomography.

In hydronephrosis, total renal volume is not correlated with renal parenchymal volume. We have used computed tomography (CT) to determine renal parenchymal volume in 17 control patients and 36 patients with unilateral hydronephrosis. An additional 17 patients were studied before and 2 weeks after renal surgery. Renal parenchymal volume was determined by summing up the parenchymal area in each scan, taken at 10 mm intervals. Renal parenchymal volume measured by CT correlated well with renal area on excretory urography in normal kidneys. Renal parenchymal volume in hydronephrosis, however, was totally unrelated to renal area on excretory urography because of the grossly dilated calyceal system. Reproducibility of this study was ascertained in 17 patients using the contralateral nonoperated kidneys before and after the surgery (r = 0.939; p less than 0.01).

Humans↗
PubMed1982

Protoplast fusion permits high-frequency transfer of a Streptomyces determinant which mediates actinomycin synthesis.

Prototrophic recombinants and heterocaryotic colonies developed at high frequency when protoplasts of nutritionally complementary actinomycin-producing and nonproducing strains of Streptomyces antibioticus were fused in the presence of polyethylene glycol and plated on minimal regeneration medium. Of the spores obtained from aerial hyphae of a single heterocaryotic colony, 99% carried the act+ character regardless of whether the nutritional markers of the spore were derived from the act+ or the act parent. Similarly, a high-frequency transfer (68% in S. antibioticus, 48% in Streptomyces parvulus) of act+ determinant(s) to act was achieved by protoplast fusion. Protoplasts of a doubly auxotrophic act strain of S. parvulus were efficiently transformed in the presence of polyethylene glycol with respect to the auxotrophic markers by DNA of an act+ auxotrophic strain with complementary nutritional requirements. The transformation frequency of the nutritional (chromosomal) markers was 17%. In contrast, the transformation frequency for actinomycin synthesis was less than 1%.

Chromosomes, Bacterial↗
PubMed1982

Control of the actinomycin biosynthetic pathway in and actinomycin resistance of Streptomyces spp.

Using actinomycin-producing and nonproducing strains of Streptomyces antibioticus, I studied several steps in the biosynthetic pathway of this antibiotic. Actinomycin-nonproducing strains derived after acriflavine or novobiocin treatment showed activity of kynurenine formamidase and phenoxazinone synthase as high as that of the parental strain, but these nonproducing strains failed to convert 4-methyl-3-hydroxy-anthranilic acid to actinomycin. In addition, accumulation of 4-methyl-3-hydroxyanthranilic acid (in the presence of D-valine) was not detected in the nonproducing isolates. Actinomycin-nonproducing strains derived after acriflavine treatment of Streptomyces parvulus showed a drastic decrease of resistance to the antibiotic. However these strains regained resistance after preincubation with a small amount of actinomycin D.

Arylformamidase↗
PubMed1982

Evidence that Bacillus subtilis sporulation induced by the stringent response is caused by the decrease in GTP or GDP.

Partial amino acid deprivation of Bacillus subtilis, which evokes the stringent response, initiates sporulation not because the highly phosphorylated guanine nucleotides guanosine-5'-diphosphate-3'-diphosphate (ppGpp) and guanosine-5'-triphosphate-3'-diphosphate (pppGpp) increase but because GTP decreases. This was shown with a mutant (Myc) partially resistant to mycophenolate, an inhibitor of IMP dehydrogenase. Upon amino acid deprivation, the Myc mutant (62032) showed the usual increase in ppGpp and pppGpp but a reduced decrease in GTP, and only few cells sporulated. Extensive sporulation was restored by the addition of mycophenolate or decoyinine, and inhibitor of GMP synthetase, which caused a further decrease in GTP.

Amino Acids↗
PubMed1982

A decrease in S-adenosylmethionine synthetase activity increases the probability of spontaneous sporulation.

Starting with a relaxed (relA) strain, mutants with reduced activity of adenosine triphosphate:L-methionine S-adenosyl transferase (EC 2.5.1.6; SAM synthetase) were isolated in Bacillus subtilis. One such mutant (gene symbol metE1) had only 3% of the normal SAM synthetase activity but grew almost as well as the parent strain. Another mutant was isolated (gene symbol spdC1) as being able to sporulate continually at a high frequency; it had one-half the normal SAM synthetase activity at 33 degrees C. Both mutants continually and spontaneously entered spore development at a higher frequency than the parent strain in a medium containing excess glucose, ammonium ions, and phosphate. Sporulation was prevented by a high concentration of SAM (1 mM or more) or by the combination of adenosine and methionine (0.5 mM or more each), both of which are precursors of SAM. In contrast to this continual increase in the spore titer, addition of decoyinine, an inhibitor of GMP synthetase, rapidly initiated massive sporulation. Various amino acid analogs also induced sporulation in the relA strain, the methionine analogs ethionine and selenomethionine being most effective.

Adenosine↗