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Biomedical subjects

H Seto

Publications and source records attributed to H Seto.

At least 73 records · Page 4Linked to original sources
PubMed1999

Experimental investigation of I-123 iodoamphetamine in the detection of lung cancer.

Experimentally we investigated the detection of lung cancer with N-isopropyl-p-I-123-iodoamphetamine (I-123 IMP). Various tumors including Lewis lung cancer were used as tumor models. Serial images were obtained. Biodistribution of Lewis lung cancer was performed. In Lewis lung cancer good visualization as in B-16 melanoma and high tumor accumulation were found with IMP. In conclusion, due to its greater accumulation almost equivalent to that in melanotic melanoma, I-123 IMP may have a role in the detection of lung cancer.

Animals↗
PubMed1999

Trabecular bone turnover, bone marrow cell development, and gene expression of bone matrix proteins after low calcium feeding in rats.

Low-calcium-fed animals have been accepted as one of the experimental models showing a reduction in bone mass. However, the effects of short-term low-calcium feeding on bone turnover, the development of osteoprogenitor cells, and gene expression of bone matrix proteins have not been reported. In this study, we examined the effect of a low-calcium diet on rat tibia and analyzed the changes in the bone by histomorphometry, bone marrow cell culture, and in situ and Northern hybridization of the bone matrix proteins. Rats were fed either a low-calcium diet (0.05% Ca) or a normal calcium diet (0.5% Ca) using the pair feeding technique. They were killed at day 0, 12 h, and days 1, 2, and 3. In the low-calcium group, the serum parathyroid hormone (PTH) level was temporarily increased in 12 h after feeding the low-calcium diet. Bone mineral density in the trabecular bone was significantly decreased from 1 day after the low-calcium feeding, but cortical bone did not show any changes during the experimental period. The bone volume per tissue volume in the proximal tibia also decreased from day 1 in the low-calcium group. The number of osteoclasts and osteoblasts on the trabecular bone surface was increased in the low-calcium group compared with the normal-calcium group. An ex vivo study showed that the number of progenitors of osteoclasts and osteoblasts in bone marrow was also increased in the low-calcium group of rats. The localization of type I collagen mRNA was observed in osteoblasts in the low-calcium group. The Northern hybridization study showed that the gene expression of type I collagen, osteopontin, and osteocalcin was increased at day 3 in the low-calcium group. These results indicated that the trabecular bone surface quickly responded to the low-calcium feeding and that bone remodeling activity was activated probably by PTH. The changes in bone marrow cell populations and the gene expression of bone matrix proteins are closely associated with increased bone turnover induced by the low-calcium diet, resulting in rapid bone loss of the trabecular bone.

Animals↗
PubMed1999

Sequential scrotal scintigraphy for the study of varicocele.

Scrotal scintigraphy is a non-invasive procedure for evaluating spermatic vein reflux. This technique was used in 43 infertile patients with varicocele. None of them had infections, traumatic, or chromosomal abnormalities that could be associated with their infertility. Twelve patients showed type 1 time activity curve, including 3 with grade II, and 9 with grade III varicocele. A total of 12 patients showed a type 2 pattern and consisted of 2 patients with grade I, 6 with grade II, and 4 with grade III varicocele. Nineteen showed type 3 pattern consisting of 6 with grade I, 6 with grade II, and 7 with grade III. The patients with grade III varicocele showed type 1 pattern more frequently than those with grade I or II (p<0.05). Preoperative sperm concentration in patients with grade I varicocele was significantly lower than that in patients with grade II or III disease (p<0.05, each). Sperm motility of patients with grade I varicocele was also significantly lower than that of those with grade II or III varicocele (p<0.01, each). Patients with grade II or III varicocele showed an increase in sperm concentration postoperatively, and those with grade I varicocele showed a postoperative increase in sperm motility, but the differences between pre- and postoperative values were not significant. While seminal findings in patients with type 2 or 3 pattern did not change after surgery, patients with type 1 pattern showed significant improvement in sperm concentration postoperatively (p<0.05). It is concluded that preoperative sequential scrotal scintigraphy can be a more useful technique for assessing the prognosis for postoperative improvement of seminal findings than the grade decision of varicocele.

Adult↗
PubMed1999

Purification, characterization, and cloning of a eubacterial 3-hydroxy-3-methylglutaryl coenzyme A reductase, a key enzyme involved in biosynthesis of terpenoids.

The eubacterial 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (EC 1.1.1.34) was purified 3,000-fold from Streptomyces sp. strain CL190 to apparent homogeneity with an overall yield of 2.1%. The purification procedure consisted of (NH4)2SO4 precipitation, heat treatment and anion exchange, hydrophobic interaction, and affinity chromatographies. The molecular mass of the enzyme was estimated to be 41 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 100 to 105 kDa by gel filtration chromatography, suggesting that the enzyme is most likely to be a dimer. The enzyme showed a pH optimum of around 7.2, with apparent Km values of 62 microM for NADPH and 7.7 microM for HMG-CoA. A gene from CL190 responsible for HMG-CoA reductase was cloned by the colony hybridization method with an oligonucleotide probe synthesized on the basis of the N-terminal sequence of the purified enzyme. The amino acid sequence of the CL190 HMG-CoA reductase revealed several limited motifs which were highly conserved and common to the eucaryotic and archaebacterial enzymes. These sequence conservations suggest a strong evolutionary pressure to maintain amino acid residues at specific positions, indicating that the conserved motifs might play important roles in the structural conformation and/or catalytic properties of the enzyme.

Amino Acid Sequence↗
PubMed1999

The effect of kampo formulae on bone resorption in vitro and in vivo. II. Detailed study of berberine.

We previously isolated berberine from aqueous extracts of tsu-kan-gan, a Kampo formula used for the treatment of osteoporosis. Berberine caused an inhibitory effect on parathyroid hormone (PTH)-stimulated bone resorption in neonatal mouse bone. In this report we describe the inhibitory effect of berberine on the formation of osteoclast-like multinucleated cells (OCLs) in the co-culture of mouse osteoblastic cells and bone marrow cells in the presence of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], PTH and interleukin-1alpha (IL-1alpha). Berberine dose-dependently inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive OCLs induced by 1alpha25(OH)2D3, PTH and IL-1alpha. We prepared OCLs in the co-culture of osteoblastic cells and bone marrow cells. The effect of berberine on pit formation by OCLs was examined using dentin slices. As OCLs are terminally differentiated multinucleated cells, the survival of OCLs affects the bone-resorbing activity of OCLs. This prompted us to count the number of TRAP-positive OCLs on the slices. Berberine dose-dependently inhibited pit formation and caused a decrease in the number of TRAP-positive OCLs. Calcitonin (CT) inhibited pit formation without affecting the number of OCLs. Berberine accelerated the cell death in OCLs cultivated on a culture plate, but CT did not affect the cell death of OCLs. This suggests that the decrease in the number of OCLs on dentin slices may be due to apoptotic cell death in OCLs. In fact, Hoechst 33258 staining revealed that the treatment of OCLs with berberine resulted in condensed nuclei and a decrease in cell size. Oral administration of the berberine (30 and 50 mg/kg/d) to ovariectomized rats prevented a decrease in bone mineral density (BMD) of the lumbar vertebra without affecting the weight of the uterus and plasma concentration of estradiol. These results suggested that berberine prevented a decrease in BMD in vivo by inhibiting osteoclastic bone resorption.

Animals↗
PubMed1999

Thallium-201 scintigraphy in malignant mesothelioma.

A patient with malignant pleural mesothelioma was investigated using 201Tl scintigraphy. There was diffuse pleural tumour accumulation on planar scintigraphy. Single photon emission computed tomography (SPECT) demonstrated exact tumour location. It is concluded that planar scintigraphy using 201Tl may be useful in detecting mesothelioma. Clearer tumour localization is possible with SPECT.

Female↗
PubMed1999

Cloning and expression in Escherichia coli of 2-hydroxypropylphosphonic acid epoxidase from the fosfomycin-producing organism, Pseudomonas syringae PB-5123.

The fosfomycin resistance gene, fosC, has been cloned from the fosfomycin-producing organism, Pseudomonas syringae PB-5123. Sequence analysis upstream of this gene found a new ORF showing significant homology to 2-hydroxypropylphosphonic acid epoxidase from fosfomycin-producing Streptomyces wedmorensis. The purified recombinant protein of this ORF converted 2-hydroxypropylphosphonic acid to fosfomycin. This result clearly showed the ORF to encode 2-hydroxypropylphosphonic acid epoxidase in PB-5123.

Amino Acid Sequence↗
PubMed1999

Construction and characterization of Escherichia coli disruptants defective in the yaeM gene.

Escherichia coli disruptants defective in the yaeM gene, which is located at 4.2 min on the chromosome map, were constructed and characterized. The disruptants showed auxotrophy for 2-C-methylerythritol, a free alcohol of 2-C-methyl-D-erythritol 4-phosphate that is a biosynthetic precursor in the nonmevalonate pathway. This result clearly shows that the yaeM gene is indeed involved in this pathway in E. coli.

Aldose-Ketose Isomerases↗
PubMed1999

Multiple myeloma evaluated with 201Tl scintigraphy compared with bone scintigraphy.

UNLABELLED: The purpose of this study was to investigate the clinical usefulness of 201Tl chloride scintigraphy in the diagnostic evaluation of 20 patients with multiple myeloma (19/20 patients) or extramedullary plasmacytoma (1/20 patients) in comparison with bone scintigraphy. METHODS: Both 201Tl and bone scintigraphy were performed to obtain planar images on the same instrument. RESULTS: 201Tl scintigraphy showed increased uptake in 15 of 20 patients (75%) and was negative in 5 of 20 patients (25%). In addition, 201Tl scintigraphy of multiple myeloma was more useful in detecting the lesions in 11 of 17 patients and less useful in 6 of 17 patients than bone scintigraphy. CONCLUSION: The combination of 201Tl and bone scintigraphy, compared with bone scintigraphy alone, shows promise in more accurately diagnosing multiple myeloma.

Bone Neoplasms↗
PubMed1998

A 1-deoxy-D-xylulose 5-phosphate reductoisomerase catalyzing the formation of 2-C-methyl-D-erythritol 4-phosphate in an alternative nonmevalonate pathway for terpenoid biosynthesis.

Several eubacteria including Esherichia coli use an alternative nonmevalonate pathway for the biosynthesis of isopentenyl diphosphate instead of the ubiquitous mevalonate pathway. In the alternative pathway, 2-C-methyl-D-erythritol or its 4-phosphate, which is proposed to be formed from 1-deoxy-D-xylulose 5-phosphate via intramolecular rearrangement followed by reduction process, is one of the biosynthetic precursors of isopentenyl diphosphate. To clone the gene(s) responsible for synthesis of 2-C-methyl-D-erythritol 4-phosphate, we prepared and selected E. coli mutants with an obligatory requirement for 2-C-methylerythritol for growth and survival. All the DNA fragments that complemented the defect in synthesizing 2-C-methyl-D-erythritol 4-phosphate of these mutants contained the yaeM gene, which is located at 4.2 min on the chromosomal map of E. coli. The gene product showed significant homologies to hypothetical proteins with unknown functions present in Haemophilus influenzae, Synechocystis sp. PCC6803, Mycobacterium tuberculosis, Helicobacter pyroli, and Bacillus subtilis. The purified recombinant yaeM gene product was overexpressed in E. coli and found to catalyze the formation of 2-C-methyl-D-erythritol 4-phosphate from 1-deoxy-D-xylulose 5-phosphate in the presence of NADPH. Replacement of NADPH with NADH decreased the reaction rate to about 1% of the original rate. The enzyme required Mn2+, Co2+, or Mg2+ as well. These data clearly show that the yaeM gene encodes an enzyme, designated 1-deoxy-D-xylulose 5-phosphate reductoisomerase, that synthesizes 2-C-methyl-D-erythritol 4-phosphate from 1-deoxy-D-xylulose 5-phosphate, in a single step by intramolecular rearrangement and reduction and that this gene is responsible for terpenoid biosynthesis in E. coli.

Aldose-Ketose Isomerases↗
PubMed1998

Purification and characterization of a 100 kDa DNA polymerase from cauliflower inflorescence.

A DNA polymerase from cauliflower (Brassica oleracea var. botrytis) inflorescence has been purified to near homogeneity through five successive column chromatographies, and temporally designated cauliflower polymerase 1. Cauliflower polymerase 1 is a monopolypeptide with a molecular mass of 100 kDa. The enzyme efficiently uses synthetic DNA homopolymers and moderately activated DNA and a synthetic RNA homopolymer as template-primers. The enzyme is strongly sensitive to dideoxythymidine triphosphate and N-ethylmaleimide, but it is insensitive to aphidicolin. It was stimulated with 250 mM KCl. Its mode of DNA synthesis is high-processive with or without proliferating-cell nuclear antigen. A 3'-->5' exonuclease activity is associated with cauliflower polymerase 1. The enzyme is clearly different from cauliflower mitochondrial polymerase and does not resemble the four different types of wheat DNA polymerase, designated wheat DNA polymerases A, B, CI and CII. In the present paper the role of the enzyme in plant DNA synthesis is discussed.

Brassica↗