Search PubMed⌕ Search

Biomedical subjects

T Akamatsu

Publications and source records attributed to T Akamatsu.

At least 109 records · Page 6Linked to original sources
PubMed1997

Chronic animal experiment with magnetically suspended centrifugal pump.

We have been developing a new type of centrifugal pump for long-term use. The magnetically suspended centrifugal pump (MSCP) contains no shaft and seal so that long life expectancy is predicted. Paracorporeal left ventricular (LV) assist circulation between the left atrium and the descending aorta was instituted using sheep. The flow rates ranged from 2.5-5.5 L/min. The sheep that lived the longest (46 days) died of an embolism as a result of the thrombus in the pump. No thrombus formation was observed in other pumps. Plasma free hemoglobin levels ranged from 9 to 18 mg/dl, which led to the conclusion that the hemolysis level remained within an acceptable range. Two driving modes were compared. The slope of the pressure-flow relationship plot under a constant motor current mode was steeper than that under a constant rotational speed mode, and thus, the flow fluctuation decreased. In conclusion, the MSCP is durable for more than a month at the current stage of development and is a promising device for long-term ventricular assist.

Animals↗
PubMed1997

Histochemistry of the surface mucous gel layer of the human colon.

BACKGROUND AND AIMS: Histochemical analysis of the surface mucous gel layer of the human colon is difficult, as it dissolves in fixatives. This study was undertaken to explore the surface mucous gel layer on the normal mucosa and neoplastic tissues of the large intestine. In addition, the distribution of different mucins secreted from goblet cells was studied with a series of histochemical stains for mucins. METHODS: Twenty four surgically resected specimens were fixed in Carnoy's solution and embedded in paraffin. In four cases, the surface mucous gel layer was also studied in frozen sections. Serial sections were stained by a battery of histochemical techniques characterising mucins. RESULTS AND CONCLUSION: The surface mucous gel layer consisted of the inner and outer layers. The first covered the luminal surface of the mucosa, consisted of mucins, and showed a vertical striped pattern. The second overlaid the first, showed a lateral striped pattern, and was contaminated with bacteria and other substances. Their thickness in paraffin sections varied considerably among the sites in the large intestine, but was the thickest in the rectum and measured 12.7 (SEM 6.0) microns and 88.8 (SEM 80.1) microns respectively. Mucins forming the inner layer were obviously derived from goblet cells underlying it.

Acetic Acid↗
PubMed1997

Drinking habit as a base for blood pressure elevation--difference in epidemiological significance by beverage type.

To investigate whether blood pressure differs by taking preferred alcoholic beverage among habitual drinkers, systolic and diastolic blood pressure (SBP, DBP) were compared among groups with different beverage types in 563 middle-aged Japanese males using data from a cross-sectional health survey conducted from February, 1989 through March, 1991 in five areas of Japan. Mean values of SBP and DBP, adjusted for residence, age and body mass index (BMI), were significantly greater in 'exclusively sake' drinkers (adjusted SBP: 127.2 mmHg, adjusted DBP: 83.0 mmHg) and in 'exclusively shochu' drinkers (adjusted SBP: 127.5 mmHg, adjusted DBP: 84.2 mmHg) than in non-drinkers (adjusted SBP: 120.9 mmHg, adjusted DBP: 77.3 mmHg). Adjusted SBP and DBP of 'exclusively beer' drinkers (adjusted SBP: 121.9 mmHg, adjusted DBP: 79.1 mmHg) were significantly (for SBP: p = 0.016, for DBP: p = 0.008) lower than those of 'exclusively sake' drinkers. Similar patterns of blood pressure differences between five beverage types of habitual drinkers were found especially in the group with less than 150 g of weekly ethyl-alcohol consumption. Even after adding ethyl-alcohol consumption as a covariate among 479 habitual drinkers, the significant differences in adjusted SBP and DBP between 'exclusively beer' drinkers and 'exclusively sake' drinkers (for SBP: p = 0.032, for DBP: p = 0.044) were noted. These results may suggest that the effects of drinking on blood pressure differ by beverage type in middle-aged Japanese males.

Adult↗
PubMed1997

Combination chemotherapy for malignant paraganglioma.

Treatment with a combination chemotherapeutic regimen consisting of cyclophosphamide, vincristine, and dacarbazine for malignant paraganglioma with hepatic metastasis is reported. A 51-year-old male presented with tumors in the retroperitoneal space and liver. The patient was diagnosed as having paraganglioma based on elevated levels of serum neuron-specific enolase, urinary catecholamine and vanillylmandelic acid, and on histological findings of the liver specimen. The patient was treated with this combination chemotherapy in repeated 21-day cycles. Temporary improvement in laboratory findings and a 20% reduction in the size of the hepatic masses were observed without severe adverse effects.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

The influence of different types of hard palate closure in two-stage palatoplasty upon palatal growth: dental cast analysis.

We investigated the influence of different types of hard palate closure in two-stage palatoplasty. In 12 cases the lip and soft palate were closed at the age of 3 to 7 months; these 12 were then divided into two groups. The hard palate was closed at the age of 1 year 5-11 months by the vomer flap with skin graft in the vomer flap (VF) Group (Osada's two-stage palatoplasty), and by push-back procedure of the mucoperiosteal flap in the push-back (PB) Group. Dental casts of the two groups were measured and compared at the ages of 0, 1, 3-4, and after 10 years. 1) In spite of apparent differences in palatal configurations at the age of 3-4 years, no significant differences in palatal size and area were noted between the groups. The cross-sectional areas in the VF Group were significantly larger than those in the PB Group in all the sections. 2) When the two groups were compared for rates of growth from 1 to 3-4 years, no significant differences in palatal size were noted, except in palatal width 1, although palatal growth from 1 to 3-4 years was more consistent and favorable in the VF Group. The rates of growth or change in palatal area and cross sectional-area 2 were significantly larger in the VF Group. 3) In spite of the apparent difference in palatal configuration, after age 10, no significant differences in palatal size, area, and depth were noted except in cross-sectional area 2.

Adolescent↗
PubMed1997

In vivo testing of a magnetically suspended centrifugal pump designed for long-term use.

The life of currently-available centrifugal pumps is limited to no more than three days. As a magnetically suspended centrifugal pump (MSCP) contains no shaft or seal, it could be expected to have a longer life expectancy. The MSCP was evaluated in a chronic animal model using eight adult sheep. Left ventricular assist with the MSCP was instituted between the left atrium and the descending aorta. The flow rates ranged from 2.5 to 6.0 L/min. The duration of the experiments ranged from 14 to 60 days. No mechanical failure occurred. The plasma free hemoglobin levels remained within an acceptable range (3-19 mg/dL). No reduction in the counts of red blood cells or platelets was observed. Thrombus formation within the MSCP was recognized in one pump. The main reason for termination was thromboembolism derived from the circuits. Three types of regulation methods (constant rotational speed, constant motor current, and controlled motor current) were also investigated. Regulation by a constant motor current mode altered the pressure-flow (P-Q) characteristics, and thereby, a steadier pump flow was obtained compared with regulation in the constant rotational speed mode. Moreover, the controlled motor current mode can change the P-Q relationship. These results demonstrate that the MSCP is a promising device for long-term use.

Animals↗
PubMed1997

Two different hard palate closure techniques in two-stage palatoplasty: effects on velopharyngeal closure and articulation.

Two different hard palate closure techniques, in two-stage palatoplasty, was evaluated in 12 patients. The lip and soft palate were closed at 3 to 7 months of age. The patients were then divided into two groups of six and the hard palate closed at 17 to 23 months of age, either by a vomer flap (VF) with a skin graft (Osada's two-stage palatoplasty) in the VF group, or by the push-back (PB) procedure of the mucoperiosteal flap in the PB group. Velopharyngeal closure (VPC) during a gag reflex before and after hard palate closure, and the articulation of these patients after closure, were evaluated and compared between the two groups. Regarding VPC before hard palate closure, three "Poor" and three "Borderline" outcomes were noted in each group. We conclude that, by introducing the pharyngeal flap, the patients in the VF group obtained good articulation, actually comparable to that in the PB group.

Articulation Disorders↗
PubMed1997

Introducing a solid model for reconstructing the severely deformed hand.

We report a case of a 39-year-old man with a severely deformed hand resulting from an injury sustained in a traffic accident at 2 years of age. A Marjolin ulcer appeared on the cicatricial area 3 years ago. After radical surgery for squamous cell carcinoma, we planned to realign the axis of the ulnarly flexed hand. Prior to surgery, we produced a solid model of the bony framework using laser lithography based on 3-D CT digital image data. The solid model furnished us and the patient with precise information on the deformity and allowed us to perform preoperative simulation surgery. By a two-stage wedge-shaped ostectomy at the end of the radius, the ulnarly deviated axis of the hand was realigned from 100 to 30 degrees (approximate) in clinical measurement and the patient was quite satisfied with the resulting function and appearance. However, there are some disadvantages of the laser lithography solid model: the cost is high, the resin material is very hard and difficult to operate on, and the model does not include soft-tissue structures. The development of a model in the future that includes vessels, nerves, and tendons will enable surgeons to transfer more precisely the results of the simulation surgery to the patient in the operating room.

Adult↗
PubMed1996

Transmission of Helicobacter pylori infection via flexible fiberoptic endoscopy.

BACKGROUND: Public concern has been raised with regard to the possibility of transmission of instrument mediated Helicobacter pylori infection after upper gastrointestinal endoscopy. METHODS: Disinfection procedures for gastrointestinal endoscopes were surveyed in 20 Japanese institutions, and in vitro bactericidal activities of seven disinfectants against H. pylori were determined. RESULTS: Screening tests for infection before endoscopy were not consistently performed; only 11 institutions always screened for hepatitis B virus, nine for hepatitis C virus, and two for tuberculosis. All 20 institutions used the same flexible fiberoptic endoscope on more than one patient in succession, with minimal cleanings only. Only two used glutaraldehyde for disinfection. Most used ethyl alcohol, benzalkonium chloride, or alkyldiaminoethylglycine hydrochloride as an external wipe. Bactericidal testing of nine strains of H. pylori against disinfectants revealed that ethyl alcohol (80%) and glutaraldehyde (0.5%) killed all nine strains within 15 seconds, whereas chlorhexidine gluconate (0.05%, 0.1%), benzalkonium chloride (0.025%, 0.1%), alkyldiaminoethylglycine hydrochloride (0.1%), povidone-iodine (0.1%), and sodium hypochlorite (150 ppm) killed all nine strains within 30 seconds. CONCLUSION: H. pylori is readily killed by many common disinfectants and antiseptics. However, practices for disinfection of flexible fiberoptic endoscope were not appropriate.

Cross Infection↗
PubMed1996

Immunohistochemical detection of Helicobacter pylori in the surface mucous gel layer and its clinicopathological significance.

BACKGROUND: Attempts have been made to develop an accurate method for detecting Helicobacter pylori in histological sections. MATERIALS AND METHODS: Biopsy specimens were obtained from the stomachs of 167 patients with gastric ulcer (33), duodenal ulcer (52), gastroduodenal ulcer (15), chronic gastritis (45), and normal mucosa (22) before antimicrobial treatment and from 108 of these patients after treatment. Biopsy specimens were (1) cultured, (2) fixed in 10% buffered formalin, or (3) fixed in Carnoy's solution. The latter method was employed to preserve the surface mucous gel layer (SMGL) covering gastric surface mucous cells. Histological sections were stained with hematoxylin and eosin (H&E), with immunostaining using a commercially available polyclonal anti-H. pylori antibody. RESULTS: Cultures were positive for H. pylori in 61% of the cases before treatment and in 16% after treatment; by H&E staining using formalin-fixed materials: 70% and 9%; by immunostaining using formalin-fixed materials: 78% and 21%; and by immunostaining using Carnoy-fixed materials: 85% and 41% of biopsy specimens, respectively. The difference in detection rates between materials fixed in formalin and those in Carnoy's solution was due to the detection of H. pylori in the SMGL by the latter, especially after antimicrobial treatment. CONCLUSIONS: Immunostaining for H. pylori using materials fixed in Carnoy's solution revealed H. pylori in the SMGL as well as on the surface mucous cells and in the gastric pits and permitted the optimal detection of H. pylori in tissue sections.

Acetic Acid↗
PubMed1996

Helicobacter pylori and the surface mucous gel layer of the human stomach.

BACKGROUND: The colonization of Helicobacter pylori in the surface mucous gel layer (SMGL) was investigated. MATERIALS AND METHODS: Surgically removed stomachs were obtained from patients and included gastric ulcer (4 cases), duodenal ulcer (2), and gastric cancer (24). Five of these cases were examined at 8, 19, 28, 143, and 171 days after the end of eradication therapy. For the preservation of the SMGL, these specimens were fixed in cold Carnoy's solution, cleared in xylene, and embedded in paraffin. Serial sections were obtained and were stained by dual staining with the galactose oxidase-cold thionin Schiff reaction followed by paradoxical Concanavalin A staining and immunostaining for H. pylori. RESULTS: H. pylori characteristically attached to surface mucous cells and colonized in the SMGL H. pylori in the SMGL was more abundant than that attached to the surface mucous cells. The degree of H. pylori infection both on the surface of surface mucous cells and in the SMGL correlated well with the severity of gastritis. In the SMGL, this organism obviously preferred to colonize in the layer of surface mucous cell-type mucins, and the multilaminated structure of the SMGL deteriorated markedly. Eradication of H. pylori restored the structure of the SMGL, and the inflammatory reaction decreased gradually. CONCLUSION: The SMGL is an indispensable site of H. pylori colonization, and this organism damaged the gastric mucosa partially by causing deterioration of the SMGL. Removal of the organism from the SMGL should be considered for eradication of this organism.

Acetic Acid↗
PubMed1996

A new magnetically suspended centrifugal pump: in vitro and preliminary in vivo assessment.

To overcome problems derived from the shaft within the conventional centrifugal pump, we have been developing a new centrifugal pump, namely a magnetically suspended centrifugal pump (MSCP), which has no shaft and operates as a noncontacting and bearingless pump. The impeller is suspended magnetically between the magnetic bearing and the driving motor. Hemolysis tests were performed in comparison with the Biopump (BP80, BioMedicus). The index of hemolysis (IH) was significantly lower in the MSCP than in the Biopump. In addition, a smaller gap in the MSCP induced lower hemolysis. In preliminary studies using mongrel dogs, the layer of thrombus adherent to the impeller was observed in a few hours, which impaired the pumping efficiency. However, by using an impeller coated with silicone, no aggregations of platelets or fibrin on the impeller were observed in 24 h of continuous pumping. In conclusion, the MSCP had a gentler influence on blood cells than the Biopump, and the impeller coated with silicone may contribute to the long-term pumping of the MSCP.

Animals↗
PubMed1996

Effect of transfection with superoxide dismutase expression plasmid on superoxide anion induced cytotoxicity in cultured rat lung cells.

Human Cu, Zn-superoxide dismutase (hSOD) cDNA was inserted into a eukaryotic expression plasmid (pRc/CMV) under the control of a cytomegalovirus promoter. The hSOD expression plasmid (pRc/CMV-SOD) was transfected into L2 cells by means of lipofection. The integration of the hSOD gene in genomic DNAs in the cells transfected with pRc/CMV-SOD plasmid was examined by Southern blotting using hSOD cDNA as the probe. However, Southern blots of host cells (without transfection) and CMV cells (pRc/CMV plasmid transfection) indicated no hybridization of hSOD cDNA. Western blots indicated that hSOD was expressed in CMV-SOD cells. The SOD activity in CMV-SOD cells was about twice that in host and CMV cells. Furthermore, this SOD activity in CMV-SOD cells was enhanced for 60 d after the selection of cell clones. After exposure to paraquat and catalase, about 90% of the CMV-SOD cells survived compared with the untreated controls, whereas about 60% of the host cells survived. The production of lipid peroxidation in host cells increased significantly after exposure to both paraquat and catalase, whereas that in CMV-SOD cells did not change. The correlation between the surviving cells and lipid peroxidation was inverse. These results indicated that transfection with the SOD gene was effective against superoxide anion induced cytotoxicity.

Animals↗
PubMed1996

Simple detection of xylosidase activity in single colonies, using 1-naphthyl-beta-D-xylopyranoside.

Since the xylosidase of Bacillus pumilus hydrolyzed 1-naphthyl-beta-D-xylopyranoside (naphthyl-X) to produce xylose and 1-naphthol and a chromogenic azo compound is produced by coupling 1-naphthol and Fast Blue Salt B, a simple method for detection of xylosidase activity in single colonies was studied. Escherichia coli JM109 carrying the xylosidase gene of B. pumilus was cultivated at 37 degrees C for 18 h on a LB plate containing 0.5 mg/ml naphthyl-X, and then the plate was overlaid with 3 ml of a top layer containing 24 mg of agar and 6 mg of Fast Blue Salt B. After incubation of the plate at 37 degrees C for 1 h, each colony became reddish-brown. Even a small colony with xylosidase on the plate was easily distinguished from colonies without the enzyme.

Bacillus↗
PubMed1996

A simple assay for xylanase using o-nitrophenyl-beta-D-xylobioside.

We measured xylanase activities upon eight chromogenic substrates, o- or p-nitrophenyl-beta-D-xylopyranoside (oNP-X or pNP-X) and o- or p-nitrophenyl-beta-D-xylooligosaccharides (oNP-Xn or pNP-Xn, n = 2-4), and studied for their uses as substrates in a kinetic study. The Kcat and K(m) of Bacillus pumilus xylanase (EC 3.2.1.8) activities for pNP-X2 were 0.24s-1 and 0.5 mM, respectively. The relative xylanase activities with the other substrates to that with pNP-X2, pNP-X3, pNP-X4, oNP-X, oNP-X2, oNP-X3, and oNP-X4 were < 0.001, 9.4, 9.7, < 0.001, 19, 190, and 200, respectively. HPLC analysis of the digestion products of oNP-X2 or pNP-X2 showed that the xylanase hydrolyzed each of the substrates only at the ether bond between nitrophenol and xylobiose. All ether bonds of pNP-X3, oNP-X3, pNP-X4, or oNP-X4 were hydrolyzed by the xylanase and further hydrolyses proceeded in the digestion products, e.g., oNP-X2 and oNP-X3 from oNP-X4. Therefore, oNP-X2 was screened as a useful substrate in a kinetic study of the xylanase. The K(m) and Kcat of the xylanase for oNP-X2 were 0.38 mM 2.29s-1, respectively. Thermodynamic studies showed that the higher reaction rate obtained with oNP-X2 than that with pNP-X2 was due to a significant decrease in the activation energy change, despite a decrease in the activation entropy change.

Bacillus↗
PubMed1996

Prediction of hemolysis in turbulent shear orifice flow.

This study proposes a method of predicting hemolysis induced by turbulent shear stress (Reynolds stress) in a simplified orifice pipe flow. In developing centrifugal blood pumps, there has been a serious problem with hemolysis at the impeller or casing edge; because of flow separation and turbulence in these regions. In the present study, hemolysis caused by turbulent shear stress must occur at high shear stress levels in regions near the edge of an orifice pipe flow. We have computed turbulent shear flow using the low-Reynolds number k-epsilon model. We found that the computed turbulent shear stress near the edge was several hundreds times that of the laminar shear stress (molecular shear stress). The peak turbulent shear stress is much greater than that obtained in conventional hemolysis testing using a viscometer apparatus. Thus, these high turbulent shear stresses should not be ignored in estimating hemolysis in this blood flow. Using an integrated power by shear force, it is optimal to determine the threshold of the turbulent shear stress by comparing computed stress levels with those of hemolysis experiments or pipe orifice blood flow.

Blood Flow Velocity↗
PubMed1996

[Gynecological management of climacteric syndrome with psychiatric disorders].

PURPOSE: To discriminate patients with severe mental disorders from those complaining of menopausal symptoms, psychological tests were performed on patients who visited the menopausal clinic. The effectiveness of hormone replacement therapy (HRT) in patients with slight mental disorders was also evaluated. SUBJECTS AND METHODS: Patients with menopausal symptoms (n = 150, 41-59 yr. old) were interviewed by a psychiatrist (according to DSM-III-R) and classified as the climacteric syndrome group (C) and the mental disorder group (P). The patients were also evaluated by the Menopausal index (MI), Maudsley Personality Inventory (MPI) and Self-rating depression Scale (SDS). The patients with severe mental disorders were eliminated and the remaining patients with menopausal symptoms were treated with conjugated equine estrogen (0.625 mg/day) and medroxyprogesterone acetate (2.5mg/day) for 24 weeks. RESULTS: 1) Thirty six patients were diagnosed as P (24%) and seven of them were diagnosed as having major depression (4.7% of the all patients). 2) MPI-N (neurosis scale) in C was 16.2 +/- 10, and in P was 30.5 +/- 9.0, and SDS in C and P were 39.0 +/- 8.0, and 51.4 +/- 8.9, respectively. In both psychological test, P shows a significantly higher value than C (p < 0.01). 3) Ninety point six % of the patients responded. HRT was not effective in 63.2% of P, but when psychotropic drugs were combined, significant improvement (p < 0.05) was observed. CONCLUSION: One fourth of the patients were suspected of having mental disorders in the menopausal clinic, and 5% of the patients needed the care of the psychiatrist. And the application of MPI and SDS was useful in helping the gynecologist to differentiate and classify the mental disorders to some extent. The applicability and effectiveness of HRT for patients with mild mental disorders were suggested.

Adult↗