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Biomedical subjects

H Saiki

Publications and source records attributed to H Saiki.

At least 37 records · Page 2Linked to original sources
PubMed1999

A novel mineral flotation process using Thiobacillus ferrooxidans.

Oxidative leaching of metals by Thiobacillus ferrooxidans has proven useful in mineral processing. Here, we report on a new use for T. ferrooxidans, in which bacterial adhesion is used to remove pyrite from mixtures of sulfide minerals during flotation. Under control conditions, the floatabilities of five sulfide minerals tested (pyrite, chalcocite, molybdenite, millerite, and galena) ranged from 90 to 99%. Upon addition of T. ferrooxidans, the floatability of pyrite was significantly suppressed to less than 20%. In contrast, addition of the bacterium had little effect on the floatabilities of the other minerals, even when they were present in relatively large quantities: their floatabilities remained in the range of 81 to 98%. T. ferrooxidans thus appears to selectively suppress pyrite floatability. As a consequence, 77 to 95% of pyrite was removed from mineral mixtures while 72 to 100% of nonpyrite sulfide minerals was recovered. The suppression of pyrite floatability was caused by bacterial adhesion to pyrite surfaces. When normalized to the mineral surface area, the number of cells adhering to pyrite was significantly larger than the number adhering to other minerals. These results suggest that flotation with T. ferrooxidans may provide a novel approach to mineral processing in which the biological functions involved in cell adhesion play a key role in the separation of minerals.

Bacterial Adhesion↗
PubMed1998

[An elderly patient with bleeding from the alimentary tract caused by aberrant pancreas of the small intestine].

A 71-year-old woman was admitted to hospital because of malaise and bloody stool. Laboratory findings consistently showed anemia (Hb 9.2 g/dl) and occult blood in the stool. Although barium series and endoscopy of the upper and lower intestinal tructs were carried out, there was no evidence of bleeding from the gastrointestinal tract 99mTcO4- scintigraphy, which was performed to exclude bleeding from Meckel's diverticulum, also did not locate a significant lesion. Angiographic imaging of the superior mesenteric arteries (SMA) was performed to exclude lesions such as small intestine tumors with extraluminal growth and vascular abnormalities such as A-V malformation and it revealed the round encasement of arteries in the peripheral SMA region, strongly suggestive of a small intestine tumor. Surgery was performed and an extraluminally protruding tumor was found in the small intestine. The excised tumor was 4 x 3 x 3.5 cm in size, are was diagnosed histologically as aberrant pancreas. The postoperative laboratory findings showed that the anemia had improved and occult blood was not detected in the stools. Although aberrant pancreas of the small intestine is a common benign tumor, it is a very unusual cause of bleeding from the alimentary tract.

Aged↗
PubMed1996

The absence of Pmp47, a putative yeast peroxisomal transporter, causes a defect in transport and folding of a specific matrix enzyme.

Candida boidinii Pmp47, an integral peroxisomal membrane protein, belongs to a family of mitochondrial solute transporters (e.g., ATP/ADP exchanger), and is the only known peroxisomal member of this family. However, its physiological and biochemical functions have been unrevealed because of the difficulties in the molecular genetics of C. boidinii. In this study, we first isolated the PMP47 gene, which was the single gene encoding for Pmp47 in a gene-engineerable strain S2 of C. boidinii. Sequence analysis revealed that it was very similar to PMP47A and PMP47B genes from a polyploidal C. Boidinii strain (ATCC32195). Next, the PMP47 gene was disrupted and the disruption strain (pmp47delta) was analyzed. Depletion of PMP47 from strain S2 resulted in a retarded growth on oleate and a complete loss of growth on methanol. Both growth substrates require peroxisomal metabolism. EM observations revealed the presence of peroxisomes in methanol- and oleate-induced cells of pmp47delta, but in reduced numbers, and the presence of material of high electron density in the cytoplasm in both cases. Methanol-induced cells of pmp47delta were investigated in detail. The activity of one of the methanol-induced peroxisome matrix enzymes, dihydroxyacetone synthase (DHAS), was not detected in pmp47delta. Further biochemical and immunocytochemical experiments revealed that the DHAS protein aggregated in the cytoplasm as an inclusion body, while two other peroxisome matrix enzymes, alcohol oxidase (AOD) and catalase, were active and found in peroxisomes. Two peroxisome-deficient mutants, strains M6 and M13 (described in previous studies), retained DHAS activity although it was mislocalized to the cytoplasm and the nucleus. We disrupted PMP47 in these peroxisome-deficient mutants. In both strains, M6-pmp47delta and M13-pmp47delta, DHAS was enzymatically active and was located in the cytoplasm and the nucleus. We suggest that an unknown small molecule, which PMP47 transports, is necessary for the folding or the translocation machinery of DHAS within peroxisomes. Pmp47 does not catalyze folding directly because active DHAS is observed in the M6-pmp47delta and M13-pmp47delta strains. Since both AOD and DHAS have the PTS1 motif sequences at their carboxyl terminal, our results first show that depletion of Pmp47 could dissect the peroxisomal import pathway (PTS1 pathway) of these proteins.

Alcohol Oxidoreductases↗
PubMed1996

Nitrogen removal by tubular gel containing Nitrosomonas europaea and Paracoccus denitrificans.

A new bioreactor for the removal of nitrogen from wastewater is described which consists of a tubular polymeric gel containing Nitrosomonas europaea and Paracoccus denitrificans. The outer surface of the tube is in aerobic contact with wastewater containing ammonia, while the inside of the tube is in anaerobic contact with ethanol flowing through the tube. N. europaea oxidizes ammonia to nitrite in the gel, and then P. denitrificans reduces the nitrite to nitrogen gas in the same gel. This concept would be effective for simplifying nitrogen removal systems requiring aerobic and anaerobic operations.

Aerobiosis↗
PubMed1995

The Candida boidinii peroxisomal membrane protein Pmp30 has a role in peroxisomal proliferation and is functionally homologous to Pmp27 from Saccharomyces cerevisiae.

The mechanism of peroxisome proliferation is poorly understood. Candida boidinii is a methylotrophic yeast that undergoes rapid and massive peroxisome proliferation and serves as a good model system for this process. Pmp30A and Pmp30B (formerly designated Pmp31 and Pmp32, respectively) are two closely related proteins in a polyploid strain of this yeast that are strongly induced by diverse peroxisome proliferators such as methanol, oleate, and D-alanine. The function of these proteins is not understood. To study this issue, we used a recently described haploid strain (S2) of C. boidinii that can be manipulated genetically. We now report that strain S2 contains a single PMP30 gene very similar in sequence (greater than 93% identity at the DNA level) to PMP30A and PMP30B. When PMP30 was disrupted, cell growth on methanol was greatly inhibited, and cells grown in both methanol and oleate had fewer, larger, and more spherical peroxisomes than wild-type cells. A similar phenotype was recently described for Saccharomyces cerevisiae cultured on oleate in which PMP27, which encodes a protein of related sequence that is important for peroxisome proliferation, was disrupted. To determine whether Pmp27 is a functional homolog of Pmp30, gentle complementation was performed. PMP30A was expressed in the PMP27 disruptant of S. cerevisiae, and PMP27 was expressed in the PMP30 disruptant of C. boidinii S2. Complementation, in terms of both cell growth and organelle size, shape, and number, was successful in both directions, although reversion to a wild-type phenotype was only partial for the PMP30 disruptant. We conclude that these proteins are functional homologs and that both Pmp30 and Pmp27 have a direct role in proliferation and organelle size rather than a role in a specific peroxisomal metabolic pathway of substrate utilization.

Amino Acid Sequence↗
PubMed1994

The phylogenetic position of Hydrogenobacter acidophilus based on 16S rRNA sequence analysis.

Hydrogenobacter acidophilus strain 3H-1 is a thermoacidophilic, obligately chemolithoautotrophic, hydrogen-oxidizer isolated from a Japanese solfataric field. Strain 3H-1 requires elemental sulfur for growth. We used PCR to amplify the 16S rRNA gene of strain 3H-1, and sequenced the amplification product directly. Phylogenetic analyses show strain 3H-1 is closely related to Aquifex pyrophilus and may be located in the deepest branch within the eubacterial phylogenetic tree. Sulfur-dependency of the ancestral eubacterium is also discussed.

Archaea↗
PubMed1994

Changes of blood volume distribution by postural changes in rats.

During a space flight the human body responds to many different gravities. The launching of the rocket, the weightlessness, the re-entry of the spacecraft, and other factors influence the astronaut's body. The fluid shifts and the effect on the cardiovascular system arising from these gravitational changes have been frequently studied in space medicine by using body tilting, lower body negative pressure (LBNP) and centrifugal accelerators. There exist, however, few reports about the changes in whole body blood volume distribution caused by body tilting. These changes can be measured using radioisotopes: scintigraphy using 99mTechnetium-labeled human serum albumin (99mTc-HSA), etc. In humans, however, because the visual field of the scintillation camera is so small, the simultaneous measurement of whole body blood volume distribution cannot be done during body tilting. We therefore used rats, whose whole bodies can be encompassed within the visual field of the camera, and we discussed the changes in blood volume distribution induced by body tilting. We also measured the blood concentrations in each organ by using whole body autoradiography in mice, and discussed the effect of postural changes on some abdominal organs.

Abdomen↗
PubMed1993

Tissue-specific molecular diversity of amidating enzymes (peptidylglycine alpha-hydroxylating monooxygenase and peptidylhydroxyglycine N-C lyase) in Xenopus laevis.

We investigated the molecular diversity of the paired enzymes, peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidylhydroxyglycine N-C lyase (PHL), involved in peptide C-terminal amidation. Three kinds of amidating enzyme (AE) cDNAs (AE-I, AE-II and AE-III) have previously been isolated from Xenopus laevis skin. While AE-I cDNA encodes only PHM, AE-III cDNA encodes a protein containing both PHM and PHL sequences and a transmembrane domain. On the other hand, the translated product of AE-II has not been detected yet. Endoproteolytic cleavage of the AE-III protein generates separated forms of PHM and PHL that are purified from X. laevis skin. Expression of AE-III in insect cells using a baculovirus expression vector system indicated that PHM and PHL exist as a membrane-associated, bifunctional enzyme without endoproteolysis in insect cells. Both PHM and PHL activities were detected in all the X. laevis tissues examined. Particularly, the highest levels of both activities were found in skin, brain and heart. We identified basically three types of enzymes in X. laevis; soluble PHM, soluble PHL and a membrane-associated, bifunctional enzyme that has both PHM and PHL domains. While the skin contained soluble types of PHM and PHL, the brain and heart predominantly contained the membrane-associated, bifunctional type. Analysis of mRNA levels by the reverse-transcript polymerase chain reaction method and Western blot analysis using PHM-specific antibody revealed that such molecular diversity of PHM and PHL among the tissues are produced by changing the ratio of AE-I mRNA/AE-III mRNA, and by endoproteolytic processing of the membrane-associated precursor protein.

Amides↗
PubMed1993

Selective Adhesion of Thiobacillus ferrooxidans to Pyrite.

Bacterial adhesion to mineral surfaces plays an important role not only in bacterial survival in natural ecosystems, but also in mining industry applications. Selective adhesion was investigated with Thiobacillus ferrooxidans by using four minerals, pyrite, quartz, chalcopyrite, and galena. Escherichia coli was used as a control bacterium. Contact angles were used as indicators of hydrophobicity, which was an important factor in the interaction between minerals and bacteria. The contact angle of E. coli in a 0.5% sodium chloride solution was 31 degrees , and the contact angle of T. ferrooxidans in a pH 2.0 sulfuric acid solution was 23 degrees . E. coli tended to adhere to more hydrophobic minerals by hydrophobic interaction, while T. ferrooxidans selectively adhered to iron-containing minerals, such as pyrite and chalcopyrite. Ferrous ion inhibited the selective adhesion of T. ferrooxidans to pyrite competitively, while ferric ion scarcely inhibited such adhesion. When selective adhesion was quenched by ferrous ion completely, adhesion of T. ferrooxidans was controlled by hydrophilic interactions. Adhesion of E. coli to pyrite exhibited a liner relationship on langmuir isotherm plots, but adhesion of T. ferrooxidans did not. T. ferrooxidans recognized the reduced iron in minerals and selectively adhered to pyrite and chalcopyrite by a strong interaction other than the physical interaction.

Journal Article↗
PubMed1992

Zonal distribution of cysteine uptake in the perfused rat liver.

When in situ perfused rat livers were administered tracer or physiologic concentrations of [35S]cysteine, a zone III (perivenous) predominance of uptake was observed in either antegrade or retrograde single-pass perfusion, as determined by quantitative densitometry of autoradiographs of liver section. This pattern remained unchanged from 30 s to 5 min observed. At higher supraphysiologic doses a more uniform acinar distribution of cysteine uptake was observed. Uptake rates of cysteine in antegrade perfusion indicated an apparent saturable component at low but physiologic cysteine concentrations. That uptake rather than metabolic trapping accounts for this perivenular pattern was supported by finding identical zonal distribution under conditions in which GSH and protein synthesis were markedly inhibited. Furthermore, increasing or decreasing hepatic cysteine pool sizes did not affect the extraction or zonation. These results suggest that a low Km transport system for cysteine is localized in zone III of the hepatic acinus.

Animals↗
PubMed1992

[A case of malignant localized visceral pleural mesothelioma].

We experienced malignant localized mesothelioma of which origin was visceral pleura. According to, 1) the preoperative chest X-ray and chest CT which showed extra-pleural sign, 2) the rapid tumor growth, and 3) the result from needle biopsy, we diagnosed malignant localized mesothelioma of which origin was parietal pleura. Surgical treatment was performed, and diagnosed that its origin was visceral pleura. The tumor invaded the lung. It is dangerous to diagnose by means of needle biopsy because of malignant cell implantation. We recommend that firstly the surgical treatment should be carried out for malignant mesothelioma, which needs extended resection for preventing its recurrence.

Humans↗
PubMed1991

[Distribution of glutathione S-transferase isozymes in rat small intestinal mucosa].

We have investigated the longitudinal distribution of glutathione S-transferase (GST) isozymes in the trisected small intestine mucosa of rats. Only GST subunits 1 and 7 were detected by Western blot analysis of the intestinal cytosol using antiserum for GST1-1, 1-2, 3-4 and 7-7. Cytosolic GST1-1, 3-4 and 7-7 were assayed by the quantitative ELISA. There was a marked decline of the concentration of GST1-1 from proximal (35.17 nmol/g tissue) to distal intestine (1.67 nmol/g tissue). GST3-4 was hardly detected in the intestinal mucosa. Among the GSTs, GST7-7 existed in the highest concentration in any segment of intestine, i.e. 58.76 nmol/g tissue (61% of GSTs) in the proximal intestine and 32.38 nmol/g tissue (93% of GSTs) in the distal intestine.

Animals↗
PubMed1990

[Comparison of intraocular penetration level of cefuzonam sodium and cefotiam after intravenous and subconjunctival injection].

We investigated the intraocular penetration of a new Cephem type antibiotic: Cefuzonam sodium (CZON) following intravenous and subconjunctival injection. CZON was administered to 28 eyes in 26 patients by 1 g intravenous injection (IV) and to 11 eyes in 10 patients by 20 mg/0.2 ml subconjunctival injection (SCI). The penetration level of CZON by the IV method was from less than 0.0025-3.35 micrograms/ml into aqueous humor, from less than 0.0025-0.315 microgram/mg into iris tissue and 2.7-157.5 micrograms/ml into serum. The penetration level of CZON by the SCI method was from less than 0.0025-12.8 micrograms/ml into aqueous humor, from less than 0.0025-0.0426 microgram/mg into iris tissue and 1.03-18.5 micrograms/ml into serum. The penetration level of CZON into aqueous humor by SCI was higher than by IV administration. In comparison with the penetration level of CZON and Cefotiam (CTM), both aqueous humor and serum levels of CTM were higher than those of CZON. These results suggested that therapeutic levels in aqueous humor effective against gram-positive and gram-negative pathogens were achieved with the 1 g IV and 20 mg SCI of CZON. However levels effective against Staphylococcus epidermidis were only erratically attained.

Adult↗
PubMed1987

Seadragon VI: a 7-day saturation dive at 31 ATA. V. Cardiovascular responses to a 90 degree body tilt.

Cardiovascular deconditioning (CD) has been reported to occur in weightlessness, bed rest, and head-out water immersion. An expanded intrathoracic blood volume results, at least initially, in all these diverse conditions. Subjects in hyperbaric environments exhibit cephalad redistribution of blood volume, which also occurs in weightlessness, bed rest, and head-out water immersion. This physiologic similarity led us to suspect that CD may also occur as a consequence of hyperbaric exposure. We examined this possibility in 3 young male subjects during a 7-d dry saturation dive at 31 ATA. Changes in blood pressure, heart rate, and stroke volume were measured before and during 15 min of the 90 degree body tilt. These changes, expressed either singly or in combination, provided indications of CD during and immediately after hyperbaric exposure. One of the principal indicators of CD was the inability to exert adequate vasoconstriction. In addition, 1 subject fainted during hyperbaric exposure, whereas no such episode occurred before or after the exposure. These findings suggest that inappropriate orthostatic reflexes may be evoked by hyperbaria and reduced physical activity over the period of confinement. It should be noted, however, that CD was already evident within 24 h of hyperbaric exposure, suggesting that the initial phase of CD was unrelated to physical confinement. We postulate that CD occurs during hyperbaric exposure as an expression of cardiovascular and neurohumoral adaptation to an expanded central blood volume with a reduced total blood volume.

Adult↗