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Biomedical subjects

S Iwamoto

Publications and source records attributed to S Iwamoto.

At least 73 records · Page 4Linked to original sources
PubMed1998

Analysis of the dielectric relaxation of a gelatin solution.

The behavior of the dielectric properties of gelatin in the frequency range from 10(3) Hz to 10(7) Hz was investigated and compared with that of the globule protein, bovine serum albumin (BSA), desalted gelatin and BSA being used. Dielectric relaxation was observed for both the gelatin and BSA solutions. The relaxation data were fitted well by the Cole-Cole equation; the Cole-Cole parameter (beta) and the relaxation time (tau) were obtained. For the BSA solutions, tau was proportional to the solution viscosity (eta) at 40 degrees C and 25 degrees C, and the values of beta at 40 degrees C were similar to those at 25 degrees C. For gelatin solution, tau was proportional to eta at 40 degrees C, but was not proportional to eta at 25 degrees C. In addition, the values of beta at 25 degrees C were smaller than those at 40 degrees C. These results indicate that the rotation of gelatin and/or polarization of submolecular groups in the coil state greatly contributed to the dielectric relaxation at 40 degrees C; on the other hand, the formation of cross-linking junctions consisting of helix structures would have affected the dielectric relaxation at 25 degrees C.

Animals↗
PubMed1998

Morphological and morphometrical study on the dorsal skin of Wistar and WBN/ILA-Ht rats in their developing stage. Evaluation of the proliferation and apoptotic processes.

The detailed histology of the dorsal skin of Wistar-derived hypotrichotic WBN/ILA-Ht rats (HtRs) was examined in their developing stage (at 3 and 7 weeks of age) using Wistar rats (WRs) as controls. As a result, except for the existence of time-lag in the hair follicular cycle and some quantitative differences, there were no essential qualitative differences between the two strains. The follicular epithelial cell number and the amounts of tonofilaments and trichohyalin granules were less in HtRs than in WRs in the same phase of hair follicular cycle. In addition, the diameter of hair shaft was significantly larger in WRs than in HtRs at 7 weeks of age. The number of proliferating cell nuclear antigen (PCNA)-positive epidermal basal cells decreased in HtRs and increased in WRs from 3 to 7 weeks of age, respectively. Apoptosis was sparsely observed in the sebaceous gland epithelial cells, keratinizing portion of hair cuticules and inner root sheath in both strains, but the frequency of apoptosis in the hair follicle was somewhat higher in 7-week-old HtRs. HtRs are considered to be useful experimental animals for dermatotoxicological studies.

Animals↗
PubMed1998

Lectin histochemistry of dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats.

A lectin histochemical study was carried out on the dorsal skin of Wistar-derived hypotrichotic WBN/Ila-Ht rats (HtRs) and Wistar rats (WRs) at 3, 7 and 24 weeks of age to clarify the lectinhistochemical characteristics of the skin during their development. The lectins examined were Concanavalia ensiformis (Con A), Dolichos biflorus agglutinin (DBA), Griffonia simpliciolia (GS-I), Helix pomatia agglutinin (HPA), Arachis hypogaea (PNA), Glycine maximus agglutinin (SBA), Ulex europeus agglutinin (UEA-I) and Triticum vulgaris agglutinin (WGA). None of the nucleated cell layers of the epidermis had DBA-binding sites, but they were all stained intensely with HPA and weakly with Con A irrespective of the strain and age of the rats. As to the other 5 lectins, the intensity of binding activity was generally weaker in HtRs than in WRs and at 3 weeks of age than at 7 or 24 weeks of age, respectively. Among them, UEA-I mainly bound to the spinous cell layer but not to the basal cell layer, suggesting that alpha-L-fucose would be expressed on the cell surface according to the differentiation of keratinocytes. In addition, GS-I, HPA and UEA-I bound to the hair follicle epithelium and many lectins stained sebaceous gland epithelial cells. In conclusion, except for the binding intensity of some lectins, there were no specific differences between HtRs and Wrs in the lectinhistochemical characteristics of the dorsal skin epidermis. The present data on the rat skin would be useful from the viewpoint of comparative lectinhistochemistry.

Animals↗
PubMed1998

[Sequential chemotherapy with methotrexate and 5-fluorouracil for advanced gastric cancer].

Sequential chemotherapy with methotrexate and 5-fluorouracil (MTX/5-FU) for advanced gastric cancer was given 29 patients. The procedure consisted of weekly MTX 100 mg/m2 (i.v.) followed three hours later by 5-FU 600 mg/m2 (i.v.) with leucovorin rescue on each of the following two days. Nine of 28 patients (32.1%) showed partial response to this treatment. Response rates were 28.6% in the 21 cases with poorly differentiated adenocarcinoma and 42.9% in the 7 cases with well- or moderately-differentiated adenocarcinoma. This procedure was especially effective for primary lesions (PR 9/20: 45%) and lymphnode metastases (CR 4 + PR 4, 8/17: 47.1%). Side effects were mild leukopenia and G-I symptoms such as nausea, diarrhea and loss of appetite, except in 1 patient who died of severe myelosuppression with sepsis. We concluded that sequential MTX/5-FU therapy is fairly effective and the adjuvant chemotherapy of choice for advanced or recurrent gastric cancer with not only poorly differentiated adenocarcinoma but also well- or moderately-differentiated adenocarcinoma.

Adenocarcinoma↗
PubMed1998

Estimation of age from the femur of Japanese cadavers.

This study was designed to estimate the age at the death of cadavers by histomorphometry of the femur. Samples from 72 Japanese males from 43 days to 92 years old and 26 females from 2 to 88 years old were used. The thickness of sections was adjusted to 50-70 microns by grinding with sandpaper. The sections were not any decalcified. They were stained with Villanueva's bone staining powder and thionin dye. The microradiographs of the sections were obtained by a soft x-ray apparatus. The area, length, width, and perimeter of the perfect osteon and haversian canal were measured. The type II osteon number, osteon fragment number, and area of triangle were also determined. These parameters were examined by an image analyzer. The parameters of the osteon showed a high correlation coefficient with age (magnitude of r > or = 0.77), whereas those of the haversian canal were low (magnitude of r < or = 0.11). All parameters were subjected to multiple regression analysis for producing a multiple regression equation of age estimation. For the stepwise selection method, the perimeter of osteon, length of the haversian canal, and osteon fragment number were selected for the equation. Their multiple r2 and standard error of estimation were 0.8874 and 6.39, respectively. For the forward selection method, in addition to the above items, three parameters, the length of osteon, area of triangle, and width of osteon, were selected. Their multiple r2 and standard error of estimation were 0.9484 and 4.884, respectively. Bone staining was useful to clarify the demarcation between osteon and fragment, leading to increased accuracy of age estimation. However, precisely estimating age for the entire range from birth to 90 years was difficult.

Adult↗
PubMed1998

[Evaluation of anomalous bile ducts using helical CT cholangiography].

PURPOSE: To evaluate the usefulness of helical CT cholangiography (DIC-CT) for laparoscopic cholecystectomy. MATERIAL AND METHODS: Prior to laparoscopic cholecystectomy, 151 patients were examined by DIC-CT. DIC-CT was performed 30 minutes after drip infusion of 100 ml of Iotroxic acid meglumine. Two-dimensional axial (2D) images with 2.5 mm or 1.5 mm slice thickness were reformatted from the raw data, and three-dimensional (3D) images were reconstructed using the surface reconstruction method. Two- and three-dimensional images were compared with the operative cholangiograms in all subjects. RESULTS: DIC-CT images of 16 cases of aberrant bile duct (10.6%) and 4 cases of anomalous junction of the cystic duct (2.6%) corresponded to the operative cholangiogram. In one case of an aberrant posterior bile duct, which drained into the common bile duct more proximally to the papilla Vater than the cystic duct did, it was difficult to diagnose correctly the anomalous junction of the bile duct on 2D images but easy on 3D images. Although another case was misdiagnosed to have double cystic ducts on 3D images, the 2D images and operative cholangiogram showed normal junction of a cystic duct. CONCLUSION: Both 2D and 3D images were useful and necessary in the evaluation of anomalous bile ducts before laparoscopic cholecystectomy.

Adult↗
PubMed1997

The release mechanism of platelet-activating factor during shear-stress induced platelet aggregation.

We previously reported that 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor, PAF), released from activated platelets stimulated with thrombin plus collagen, is associated with platelet microparticles. In the present study, we found that PAF is concentrated and associated with microparticles released from high shear stress-induced activated platelets. The total amount of PAF released from 3 x 10(8) platelets under high shear stress (108 dyne/cm2) was 3.2 +/- 0.6 x 10(-15)mol (n = 5, mean +/- S.D.). Eighty percent of the PAF released from the platelets was recovered in the microparticle fraction after ultracentrifugation in the presence of albumin. Under high shear stress, PAF was not released from platelets within 3 minutes, although microparticles were released. In conclusion, microparticles released from activated platelets in the rheological condition of high shear stress are major carriers of PAF.

Animals↗
PubMed1997

The RHD gene is highly detectable in RhD-negative Japanese donors.

Recent molecular studies on the Rh blood group system have shown that the Rh locus of each haploid RhD-positive chromosome is composed of two structural genes: RHD and RHCE, whereas the locus is made of a single gene (RHCE) on each haploid RhD-negative chromosome. We analyzed the presence or absence of the RHD gene in 130 Japanese RhD-negative donors using the PCR method. The RhD-negative phenotypes consisted of 34 ccEe, 27 ccee, 17 ccEE, 26 Ccee, 19 CcEe, 1 CcEE, and 6 CCee. Among them, 36 (27.7%) donors demonstrated the presence of the RHD gene. Others showed gross or partial deletions of the RHD gene. These results were confirmed by Southern blot analysis. Additionally, the RHD gene detected in the RhD-negative donors seemed to be intact through sequencing of the RhD polypeptide cDNA and the promoter region of RHD gene. The phenotypes of these donors with the RHD gene were CC or Cc, but not cc. It suggested that there is some relationship between the RHD gene and the RhC phenotypes in RhD-negative individuals. In Caucasian RhD-negative individuals, the RHD gene has not been found outside of the report of Hyland et al. (Hyland, C.A., L.C. Wolter, and A. Saul. 1994. Blood. 84:321-324). The discrepant data on the RHD gene in RhD-negative donors between Japanese and Caucasians appear to be derived from the difference of the frequency of RhD-negative and RhC-positive phenotypes. Careful attention is necessary for clinicians in applying RhD genotyping to clinical medicine.

Base Sequence↗
PubMed1997

Sclerotherapy for varicose veins of the lower legs in patients with dysplasminogenemia.

Sclerotherapy combined with ligation has become a widely accepted treatment for varicose veins; however, it is associated with some risk of the serious complications of deep vein thrombosis (DVT). We investigated the incidence of thrombophilia in 164 consecutive patients undergoing treatment for varicose veins and determined the activities of antithrombin-III, protein C, and plasminogen. Of the 164 patients, 10 were diagnosed as having dysplasminogenemia (DPG), showing an incidence of 6.1%, in accordance with previous reports. DVT was not found to be caused by DPG in any patient, and no difference was found between patients with and those without DPG, suggesting that DPG is not a risk factor for varicose veins. We also investigated the activation of coagulation by measuring the thrombin-antithrombin III complex (TAT). The activation of coagulation after sclerotherapy was inhibited when ligation was performed 1 month prior to sclerotherapy, whereas it was increased when sclerotherapy and ligation were performed simultaneously. Of the 10 patients with DPG, 5 were treated uneventfully, and their TAT level increased to 4.0 micrograms/l, which was comparable to the level after sclerotherapy and ligation. These findings indicate that sclerotherapy can be performed safely in the majority of patients with DPG, and that the temporal separation of sclerotherapy and surgery is an alternative for these patients to prevent the activation of coagulation.

Adult↗
PubMed1997

Dinucleotide repeat in the 3' flanking region provides a clue to the molecular evolution of the Duffy gene.

The Duffy blood group system consists of three alleles, FYA, FYB, and FY. To study the molecular evolution of the three alleles, we established the polymorphism of a dinucleotide (GT) repeat sequence (designated FyGT/C) in the 3' flanking region of the Duffy gene, and studied the relationship between FyGT/C and Duffy polymorphism in Japanese, people of African origin, and chimpanzee. By single-strand conformation polymorphism and sequence analysis, five and two alleles were identified in Japanese and Africans, respectively. In 110 random Japanese, the FyGT/C genotypes observed were in agreement with Hardy-Weinberg law. From the sequence of the chimpanzee Duffy gene, including both flanking regions, FYB was identified as the ancestral gene of the human alleles. The FyGT/C sequences associated with the FY allele of Africans were distinct from those of Duffy positives, whereas the FYB and FYA alleles shared common FyGT/C sequences. Thus, it is suggested that the first split took place between the FYB and FY alleles, and the second between the FYB and FYA alleles.

Alleles↗
PubMed1997

Identification of the truncated Duffy mRNAs in erythroid cells.

Chaudhruri et al. reported the Duffy glycoprotein cDNA (Fy71-81) (Proc Natl Acad Sci USA 1990; 90; 10793), and we cloned a novel Duffy cDNA named Fy0.1 (Blood 1996; 87: 378). Reverse transcription-polymerase chain reaction analysis revealed the presence of the four truncated mRNAs associated with both transcripts. The truncated Duffy mRNAs is predominantly present in reticulocytes but is not detected in the erythroblasts. The sequencing data indicated that the truncated Duffy mRNAs were processed by splicing. Further study is needed to clarify the biological role of the truncated Duffy mRNA in reticulocytes.

Animals↗
PubMed1997

Case report: right-sided periadrenal metastasis supplied by the hepatic artery. Clue to the genesis of pedunculated hepatocellular carcinoma.

The adrenal is the second most common site of haematogenous metastasis of hepatocellular carcinoma (HCC). The right adrenal is much more frequently affected than the left, but no reason has been offered for this difference. An aetiological connection has never been suggested between adrenal metastasis and pedunculated HCC. Hepatocellular carcinoma was resected in two patients who subsequently developed right-sided adrenal metastasis diagnosed by imaging. The adrenal mass was enhanced by hepatic arteriography and took up lipiodol injected into the hepatic artery. Reoperation was performed to remove the adrenal mass, which was abutting on the liver but was readily separable. Histopathologically, the adrenal gland was compressed by a metastatic HCC that developed in the immediate periadrenal tissue or adrenal capsule. By conventional imaging, the adrenal gland could not be recognized and the mass was thought to have arisen within the adrenal gland. In conclusion, periadrenal growth of HCC is a hitherto unrecognized type of metastasis and must have been mistaken either for an adrenal metastasis or a pedunculated HCC in the past. If left unresected, it would have fused with the liver and grown into a pedunculated HCC. Cancer cell invasion through an adrenohepatic fusion is the most likely mode of periadrenal metastasis; it explains the arterial communication between the mass and the liver.

Adrenal Gland Neoplasms↗
PubMed1997

Induction of cell killing, mutation and umu gene expression by 6-mercaptopurine or 2-thiouracil with UVA irradiation.

When Escherichia coli cells were irradiated by UVA in the presence of 6-mercaptopurine (6-MP) or 2-thiouracil (S2Ura), two kinds of repair-deficient strains of recA- and uvrA- were killed more efficiently than the parental wild-type strain having normal repair capacities. In addition, these agents with UVA exposure greatly induced the incidence of mutations in the uvrA- strain as compared with the wild-type strain but not the recA- strain. Furthermore, the induction of expression of umuDC genes was investigated in two Salmonella typhimurium strains, TA1535 and TA1538, carrying a pSK1002 plasmid. In these systems, it is easy to measure beta-galactosidase activities for the induced activities of SOS responses. These agents with UVA exposure also induced expression of the umuDC genes. These results suggest that 6-MP and S2Ura with UVA induce DNA damage which is repairable by the excision repair mechanism.

Adenosine Triphosphatases↗
PubMed1997

Hydrogen peroxide-induced dermatitis in WBN/Kob-Ht rats.

Light and electron microscopic examinations were carried out on the dorsal skin to which hydrogen peroxide (HPO) (3, 6, and 10%) was topically applied for 7 consecutive days in Wistar rat-derived inbred WBN/Kob-Ht rats which have an autosomal dominant gene responsible for their characteristics of hypotrichosis. In addition to focal epidermal thickening, keratinocyte necrosis, dermal mononuclear cell infiltration and focal detachment of the epidermis from the dermis by fluid-filled spaces were detected. This is thought to be brought about by edema due to prominent capillary endothelial damage in the superficial dermis. The damage to keratinocytes and capillary endothelial cells was thought to be induced by HPO itself and free radicals generated by HPO. In addition, these changes were apparently more severe in WBN/Kob-Ht rats than in Wistar rats used as controls.

Animals↗
PubMed1997

Effects of 20 days horizontal bed rest on mechanical efficiency during steady state exercise at mild-moderate work intensities in young subjects.

Delta efficiency(DE) at mild-moderate (31%-56% of maximum oxygen uptake) bicycle exercise in the upright sitting and in the supine position was measured in 10 young males and 5 females before and after 20 days bed rest (BR). Total muscle mass in the both legs(TMML) were measured by dual-energy x-ray absorptiometry. After BR, oxygen uptake decreased at all intensities during upright exercise and at 100 W during supine exercise (p<0.05) in the males but cardiac output (acetylene rebreathing) was almost unchanged. As defined as increase in work over the corresponding increase in energy liberation, DE significantly increased by 20.1% during upright exercise and 18.4% during supine exercise in males, but unchanged in females. TMML was decreased in both males and females. The differences in DE between males and females could not be explained in the present study. One possibility might be that the decreased DE was due to a simultaneous decrease in slow twitch muscle fiber content which might be responsible for the decreased TMML induced by BR in the males.

Adult↗
PubMed1997

Cardiovascular response to lower body negative pressure before and after 20 days horizontal bed rest.

To evaluate the effects of 20 days bed rest (BR) on cardiovascular system in normal subjects, left ventricular (LV) echocardiography and vascular ultrasound of the common carotid artery and abdominal aorta were performed during rest and a supine lower body negative pressure (LBNP) test in 14 healthy volunteers (mean age: 22 years) before and after BR. After BR, heart rates (HR) at rest and during LBNP (-40 mmHg) increased. In contrast, LV dimensions, stroke volume, and blood pressures decreased both at rest and during LBNP. Also LBNP tolerance time decreased after BR. Although resting cardiac output (CO) and abdominal aortic flow decreased after bed rest, CO and abdominal aortic flow were unchanged during LBNP comparing before and after BR. Common carotid artery flows both at rest and during LBNP showed no change after BR. LBNP did not increase HR before BR, but increased HR prominently after BR. In conclusion, LBNP tolerance time and LV size during LBNP decreased after BR, suggesting orthostatic intolerance due to a decreased blood volume. However, CO and flow in the abdominal aorta and common carotid artery during LBNP were similar before and after BR due to a compensatory increase after BR.

Adult↗
PubMed1997

Beta-blockade does not improve orthostatic intolerance induced by 20 days bed rest.

To assess if propranolol influences orthostatic intolerance induced by prolonged bed rest (BR), a lower body negative pressure test (LBNP) and left ventricular (LV) echocardiography before and during -40mmHg of LBNP were performed with and without intravenous propranolol administration (0.04mg/kg) in 9 healthy volunteers (mean age: 21 years) before and after 20 days BR. LBNP tolerance time (LBNP-T), endpoint heart rate(HR), and percentage changes from 0 to -40mmHg LBNP in HR, LV diastolic dimension(LVDd), stroke volume (SV), cardiac output (CO), and systemic vascular resistance(SVR) were measured. After BR, percentage changes in CO during LBNP was not altered by propranolol (-12+/-21% vs. -24+/-24%; with and without propranolol; p>0.05) because the effect on percentage changes in HR (18+/-11% vs. 26+/-12%; p<0.05) cancelled out the effects of percentage changes in LVDd (-9+/-6% vs. -15+/-10%; p<0.05) and percentage changes in SV (-26+/-16% vs. -39+/-22%; p<0.05). In addition, propranolol decreased end-point HR (85+/-15bpm vs. 119+/-l4bpm; p<0.05) and percentage changes in SVR (25+/-32% vs. 53+/-57%; p<0.05). As a result, LBNP-T after BR was unchanged by propranolol (8.8+/-3.3min vs. 10.8+/-5.0min; p>0.05). In conclusion, propranolol failed to change orthostatic intolerance induced by BR.

Adrenergic beta-Antagonists↗