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Biomedical subjects

K Nakata

Publications and source records attributed to K Nakata.

At least 145 records · Page 8Linked to original sources

Refractory hepatic hydrothorax treated with transjugular intrahepatic portosystemic shunt.

A 66-year-old cirrhotic woman was referred to our hospital for evaluation of refractory pleural effusion and dyspnea. Massive right sided-pleural effusion but no ascites was detected. She had been treated with diuretics and albumin, repeated thoracenteses, and pleural drainage with an intercostal catheter, all of which had failed to relieve her symptoms. The diagnosis of hepatic hydrothorax without ascites was made by injection of technetium-99m-sulfur colloid into the peritoneal cavity. A transjugular intrahepatic portosystemic shunt was placed and successfully reduced the pleural effusion, resulting in complete relief of her symptoms. The patient has been free of symptoms for 18 months after the procedure.

Aged↗

Clinical features of 89 patients with autoimmune hepatitis in Nagasaki Prefecture, Japan.

We examined the clinical characteristics of 89 patients with autoimmune hepatitis (AIH) in Nagasaki Prefecture, Japan, and assessed the usefulness of a provisional scoring system for the diagnosis of AIH proposed by the International Autoimmune Hepatitis Group in 1993. The majority of patients were middle-aged women in their fifties. All patients showed a hepatitic picture. Forty-three patients (48%) had an insidious or chronic onset, while 34 (38%) had an acute onset, and 12 (14%) had liver cirrhosis at presentation. Seventy-nine patients (89%) were positive for antinuclear antibody (ANA), and 5 (6%) were positive for antibody to the hepatitis C virus (anti-HCV). The prognosis was good, with 90% 3-year survival, and most patients responded well to treatment with corticosteroids. The international scoring system was useful for the diagnosis of AIH in most of our patients; the percentages of patients with definite and probable AIH were 48% and 47%, respectively. However, certain factors, such as negative ANA, positive antimitochondrial antibody, concurrent infection with hepatitis B or C virus, and insufficient response to treatment precluded the diagnosis of AIH in some patients. Whether these patients were indeed "true" AIH patients is not clear at present, and further investigation of such patients may be useful for a better understanding of AIH.

Adolescent↗

Association of diffuse panbronchiolitis with microsatellite polymorphism of the human interleukin 8 (IL-8) gene.

Diffuse panbronchiolitis (DPB) is a distinctive chronic inflammatory lung disease predominantly found in Asian populations. Although its etiology is unknown, DPB is considered to be a multifactorial disease of whose susceptibility is determined by genetic predisposition unique to Asians. We and others have previously reported that the B*5401 allele of the human leukocyte antigen (HLA)-B gene or a closely linked gene in the HLA region on 6p21.3 is one of the major genetic factors in susceptibility to this disease. However, the association with B*5401 is not absolute and the contribution of other genetic or environmental factors should also be considered. Here, four candidate genes that are postulated to play a role in the pathophysiology of DPB, namely, RON-kinase, CYP3A4, motilin, and interleukin (IL)-8, were chosen, and association studies between microsatellite markers at these loci and DPB were conducted. We demonstrated the presence of a specific allele at the IL-8 locus was associated with the disease (c2 = 9.13; P = 0.0025; corrected P [Pc] < 0.05). Although further studies are needed to examine whether neutrophil accumulation in the airways of patients with DPB is controlled by a possible genetic variation of IL-8 or other chemokine genes located in the region 4q12-q13, our data suggest that genes other than those of the HLA system may also contribute to a genetic predisposition to DPB.

Asian People↗

Development of a totally implantable biventricular bypass centrifugal blood pump system.

BACKGROUND: During the past 2 years, the development of a totally implantable biventricular bypass rotary blood pump system has been made. METHODS: An extracorporeal gyro centrifugal pump, the CIE3, was miniaturized and developed into the PI601, a totally implantable plastic pump. Two-day anatomic and hemodynamic feasibility studies demonstrated that these two pump systems were easily implantable inside a calf's abdominal wall, directly under the diaphragm. The priming volume of the pump was 20 mL, with sufficient cardiac outputs at approximately 2,000 rpm and requiring less than 10 W of power. Two-week antithrombogenic screening tests also revealed these pump systems to be quite antithrombogenic. In addition, 1-month system reliability studies demonstrated fail-safe reliable performances. RESULTS AND CONCLUSIONS: Encouraged by these preliminary studies, the PI601 model was converted to the permanently implantable titanium gyro pump PI702 model. The long-term implantations were initiated approximately 3 months ago, and two such long-term LVAD studies are currently underway with no sign of difficulty (October 10, 1997). They were followed 283 days and 72 days, respectively. Both terminated due to functional inflow obstruction. There were no blood clots or emboli at autopsy.

Animals↗

Effect of simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on alpha-fetoprotein gene expression through interaction with the ras-mediated pathway.

BACKGROUND/AIMS: The ras proto-oncogene encodes a small GTP-binding protein (Ras) which regulates cell growth and differentiation by relaying signals from the cell surface to the nucleus. In the present study, the role of Ras signal transduction pathway in alpha-fetoprotein (AFP) gene expression was evaluated in HuH-7 human hepatoma cells using simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, which blocks Ras function through inhibition of farnesylation, and the ras(val-12) expression vector. METHODS: The HuH-7 cells were treated with simvastatin (10 micromol/l), or both simvastatin and mevalonate (300 micromol/l), and numbers of viable cells were counted after treatment. To elucidate the effects of simvastatin on AFP gene expression and the interactive effect of simvastatin on Ras signal transduction pathway, Northern blotting and transient chloramphenicol acetyltransferase plasmid transfection assays were performed. RESULTS: Cell growth was inhibited by simvastatin, and this growth inhibition was restored by addition of mevalonate. Levels of AFP mRNA but not albumin mRNA were elevated by simvastatin in a dose-dependent manner (1-10 micromol/l). AFP promoter and enhancer activities were stimulated by simvastatin. In contrast, both activities were repressed by transfection with the ras(val-12) expression vector. The ras(val-12)-mediated repression was restored by simvastatin and returned to the repressed level by simvastatin plus mevalonate. CONCLUSIONS: These results indicate that the Ras signal transduction pathway functions to down-regulate the AFP gene transcription in human hepatoma cells.

Carcinoma, Hepatocellular↗

Use of FDP and F1P aldolase to detect tumorous and nontumorous tissue damage by ethanol injection of hepatocellular carcinoma.

Changes in serum levels of tumor-specific fructose 1,6-diphosphate (FDP) aldolase and nontumor-specific fructose 1-phosphate (F1P) aldolase activities were analyzed in patients with hepatocellular carcinoma (HCC) to detect the damage of tumorous and nontumorous hepatic cells after percutaneous ethanol injection (PEI). Initial PEI was performed in 20 patients containing 22 HCC nodules with a diameter of < or = 4 cm. Changes in serum hepatic enzyme activities were measured before and after repeated PEI. FDP and F1P aldolase levels were measured by substrate-specific enzymatic methods. Pre- and posttreatment alpha-fetoprotein (AFP) levels were determined by radioimmunoassay. The consequent changes in the total nontumorous liver volumes after PEI were also analyzed by follow-up CT scans. Serum levels of FDP aldolase released by ethanol injection were progressively increased (P < 0.0001) until the third PEI and thereafter decreased. In contrast, serum levels of F1P aldolase were continuously elevated even after the third PEI (P < 0.0001). Serum levels of transaminases were also elevated after repeated PEI (P < 0.0001). The FDP/FIP aldolase ratio decreased significantly with increased volume (>20 ml) of injected ethanol (P = 0.01) caused by nontumorous liver damage. The elevation of FDP aldolase was markedly associated with a decrease in serum levels of AFP (P < 0.001), indicating adequate tumor necrosis. The progression of the total nontumor liver atrophy depended on the volume of injected ethanol and correlated significantly with F1P aldolase levels after PEI (P < 0.01) but not with FDP aldolase. These results demonstrated that caution is needed to avoid nontumorous liver damage caused by the large volume of ethanol injection in treating HCC. Measurement of FDP and F1P aldolase activities in serum after PEI is clinically useful to detect the degree of tumorous and nontumorous tissue damage by ethanol.

Aged↗

Contribution of TAP genes to genetic predisposition for diffuse panbronchiolitis.

Diffuse panbronchiolitis is a chronic obstructive pulmonary disease found in Asian populations. Although diffuse panbronchiolitis is considered to be a multifactorial disease of unknown etiology, the disease susceptibility appears to be determined by a genetic predisposition unique to Asians. An earlier study showed that human leukocyte antigen (HLA)-B54 predominantly found in East Asians was strongly associated with the disease. A possible interpretation of this association is that the class I molecule or class I antigen presenting system is directly involved in its pathogenesis. Recent observations in which impaired expression of class I molecules causes a syndrome resembling diffuse panbronchiolitis further prompted us to test this possibility. Genes of the molecules implicated in the class I pathway, TAP1, TAP2 and LMP2, which are located in the HLA region of the sixth chromosome were analyzed in 76 patients with diffuse panbronchiolitis and 120 normal controls. The combination of Ala-665 and Gln-687 in exon 11 of the TAP2 gene was associated with the disease (P=0.0028, Pc<0.05). Although this positive association might be partly explained by linkage disequilibrium with HLA-B*5401, this TAP2 variation was associated with the disease even in the B*5401-negative subgroup. On the other hand, the His-60 substitution within the LMP2 gene exhibited a negative association with the disease. This negative association, however, could be explained by a strong linkage disequilibrium with HLA-B44 which showed a negative association with the disease in the previous study. These results support the notion that diffuse panbronchiolitis is influenced by genetic factors in the HLA region. Besides the class I gene itself, genes relevant to the class I antigen presenting system might contribute to its genetic predisposition.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Utilization of variant-type of human alpha-fetoprotein promoter in gene therapy targeting for hepatocellular carcinoma.

We previously reported that the retroviral vector (LNAFW0.3TK) expressing the herpes simplex thymidine kinase (HSVtk) gene under the control of the 0.3 kb human alpha-fetoprotein (AFP) promoter provided the ganciclovir (GCV)-mediated cytotoxicity in the high AFP-producing (HuH-7) but not in the low AFP-producing (huH-1/cl.2) human hepatoma cells. In the present study, we constructed the retroviral vector (LNAFM0.3TK) in which the HSVtk gene expression is regulated by the variant-type of the 0.3 kb human AFP promoter with a G-to-A substitution at nucleotide -119, a point mutation responsible for hereditary persistence of human AFP and the vector was applied to three human hepatoma cell lines HuH-7, huH-1/cl.2 and intermediate AFP-producing cells (PLC/PRF/5). By the reporter gene transfection assay, the activity of the variant-type of the promoter was much higher than that of the wild-type of the promoter in both HuH-7 and huH-1/cl.2 cells. Consistent with this, LNAFM0.3TK infection could sensitize huH-1/cl.2 cells, as well as HuH-7 and PLC/PRF/5 cells to GCV, but did not affect cell growth of nonhepatoma cells (HeLa). In addition, the bystander effect was achieved more efficiently by LNAFM0.3TK infection than LNAFW0.3TK infection in HuH-7 cells. These results suggest that the variant-type of the human AFP promoter ensures the therapeutic gene expression in gene therapy particularly for the low AFP-producing hepatoma cells.

Carcinoma, Hepatocellular↗

Sodium butyrate induces alkaline phosphatase gene expression in human hepatoma cells.

BACKGROUND AND AIMS: Butyrate, a natural product of colonic bacterial flora, has been reported to increase the activities of a number of enzymes, including alkaline phosphatase, (ALP) in several cancer cell lines. However, butyrate-induced ALP gene expression in human hepatoma cells has not been previously demonstrated. In the present study, the effects of sodium butyrate on cell growth and proliferation, cellular activity and expression of ALP gene in human hepatoblastoma-derived HepG2 cells were investigated. METHODS: The HepG2 cells were treated with sodium butyrate (0-1 mmol/L) and the number of viable cells were counted at 24, 48 and 72 h after treatment. A [3H]-thymidine incorporation study was performed at different concentrations of sodium butyrate for 48 h. The cellular activity of ALP in HepG2 cells by sodium butyrate was measured by a substrate-specific enzymatic assay. To elucidate the effects of sodium butyrate on ALP gene expression, a northern blotting experiment employing hybridization with mouse placental ALP cDNA was performed. RESULTS: Cell growth and proliferation were dose-dependently inhibited by sodium butyrate. Cellular ALP activity was significantly increased in HepG2 cells in a time- and dose-dependent fashion by treatment with sodium butyrate and a maximum activity was observed at 48 h. These effects were reversible when sodium butyrate was removed from the culture medium. By northern blot analysis, the level of ALP messenger RNA was dose-dependently elevated by sodium butyrate. CONCLUSION: Butyrate, at a concentration relevant to the normal physiology of the liver, causes augmented expression of ALP mRNA in HepG2 cells. We assume that increased ALP synthesis in HepG2 cells by sodium butyrate results from an enhanced rate of transcription rather than translation of mRNA.

Alkaline Phosphatase↗

Major organ function under mechanical support: comparative studies of pulsatile and nonpulsatile circulation.

We examined a major organ function during 3 h biventricular assisted circulation after acute myocardial infarction model in the pig. In left ventricular circulation, the outflow cannula was placed in the ascending aorta and an inflow cannula through the mitral valve in the left ventricle. A pump (pulsatile group, Zeon Medical, Inc., Tokyo, Japan and nonpulsatile group, Nikkiso HPM-15, Nikkiso, Inc., Tokyo, Japan) was connected to each cannula. In right ventricular circulation, the outflow cannula was placed in the pulmonary artery and an inflow cannula in the right ventricle. The right ventricular circulation was supported by a nonpulsatile pump (Nikkiso HPM-15). The items measured were the regional blood flows of the cortex and medulla in the kidney, white matter and gray mater in brain, and liver; renal arterial flow; carotid arterial flow; portal vein flow; common hepatic arterial flow; arterial ketone body ratio (AKBR); and lactate/pyrubic acid (L/P). In the pulsatile group, the renal cortical blood flow increased, and the medulla blood flow decreased. On the other hand, in the nonpulsatile group, both regional blood flows decreased. That means that in the pulsatile assisted group intrarenal redistribution improved rather than in the nonpulsatile assisted group. In addition the liver regional blood flow, AKBR, and L/P showed significant differences between the pulsatile and nonpulsatile groups. On the other hand, the white matter and gray matter regional blood flows and carotid arterial flow did not show significant differences between the groups. The results of our study indicated that pulsatile circulation produced superior circulation in the kidney and liver, and microcirculation on the cell level was superior as well in early treatment of acute heart failure.

Animals↗

Long-term in vivo left ventricular assist device study for 284 days with Gyro PI pump.

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, the Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart (TAH), 2 week screening tests for anti-thrombogenecity, and a 1 month system feasibility study. Based upon these results, a metallic prototype, the Gyro PI 700 series, was subjected to long-term in vivo left ventricular assist device (LVAD) studies of over 1 month. The Gyro PI 700 series has the same inner dimension and same characteristics of the Gyro PI 601 such as an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI metallic pump is also driven with the Vienna DC brushless motor actuator like the PI 601. The pump-actuator package was implanted in 3 calves in the preperitoneal space, bypassing from the left ventricular (LV) apex to the descending aorta. Case 1 achieved a 284 day survival. Case 2 was euthanized early at 72 postoperative days as a result of the functional obstruction of the inlet port due to the excessive growth of the calf. There was no blood clot inside the pumps of either case. Case 3 is on-going (22 days on July 24, 1998). During these periods, all cases showed no physiological abnormalities. In conclusion, the PI 700 series pump has excellent results as a long-term implantable LVAD.

Animals↗

Cytokine and endothelial damage in pulsatile and nonpulsatile cardiopulmonary bypass.

Recently, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB). However, according to the results of our experimental studies, after cardiogenic shock, pulsatile flow was effective in maintaining the functions and microcirculations of end organs, especially those of the liver and kidney. To estimate the effectiveness of pulsatility during CPB, cytokine and endothelin and other metabolic parameters were measured in clinical pulsatile and nonpulsatile CPB cases. From March to May 1997, CPB was performed in 18 elective cases (14 ischemic and 4 valvular disease). In 9 cases, pulsatile perfusion was achieved by the Jostra HL20, which is a newly developed CPB pump (Group P). A nonpulsatile centrifugal pump was used in 9 patients (Group NP). In both groups, as chemical and metabolic mediators, interleukin-8 (IL-8), endothelin-1 (ET-1), and plasma free hemoglobin were measured before and during CPB, and 0.5, 3, 6, 9, 18 h after weaning from CPB. This pulsatile CPB pump could be very simply and easily controlled and could easily produce pulsatile flow. There were no significant differences in CPB time (CPBT), aortic cross clamp time (ACCT), mean aortic pressure, or pump flow during CPB between the both groups. The ET-1 level of Group P was significantly (p < 0.05) lower than that of Group NP 9 h after CPB weaning. The IL-8 level of Group P also showed a lower value than that of Group NP. As for plasma free hemoglobin, there were no significant differences between the groups. These results suggested that even in conventional CPB, pulsatility was effective to reduce endothelial damage and suppress cytokine activation. It may play a important role in maintaining the functions and microcirculations of end organs during CPB.

Aged↗

A new control method that estimates the backflow in a centrifugal pump.

The rotary blood pump will be widely used in the near future as an implantable left ventricular assist device (LVAD). However, one obstacle for the centrifugal pump is a control method that can maintain an optimum flow rate in a physiological condition. Thus, the object of this study is to develop this optimum control system for the centrifugal pump. If the heart function and pump efficiency are stable, the ratio of the systole current to the the diastole current (S/D) will be a fixed value. However, if the heart function and pump efficiency are unstable, S/D will not be a fixed value. This control system was investigated with a calf that was subjected to an ex vivo LVAD study. The LVAD was a Gyro C1E3 centrifugal pump. The pump flow rate was changed to 1.5, 3.5, 5.2, and 6.2 L/min. According to the changes of the pump flow rates, the S/D values were 1.01 +/- 0.01, 1.06 +/- 0.05, 1.03 +/- 0.01, and 1.03 +/- 0.01, respectively. There was no statistical difference among the 3 groups. In a separate experiment, the backflow condition S/D was 1.88 +/- 0.6, and the normal condition S/D was 1.35 +/- 0.5. There was a statistical difference between the 2 groups. The results of this study suggest that S/D is not influenced by the pump flow rate. However, the S/D was changed when the pump was in a backflow condition. This method will be useful in controlling a centrifugal pump requiring only electrical current information.

Analysis of Variance↗

An emergency balloon occlusion system for a rotary blood pump left ventricular assist system.

A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary blood pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary blood pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail-safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary blood pump LVAS.

Animals↗

Feasibility of a tiny Gyro centrifugal pump as an implantable ventricular assist device.

The Gyro pumps were developed for long-term circulatory support. The first generation Gyro pump (C1E3) achieved 1 month paracorporeal circulatory support in chronic animal experiments; the second generation (PI702) implantable ventricular assist device (VAD) was successful for over 6 months. The objective of the next generation Gyro pump is for use as a long-term totally implantable VAD and for pediatric circulatory support. This tiny Gyro pump (KP101) was fabricated with the same design concept as the other Gyro pumps. The possibility of an implantable VAD was determined after performance and hemolysis test results were compared to those of the other Gyro pumps. The pump housing and impeller were fabricated from polycarbonate with an impeller diameter of 35 mm. The diameter and height of the pump housings are 52.3 mm and 29.9 mm, respectively. At this time, a DC brushless motor drives the KP101, which is the same as that for the C1E3. The pump performance was measured in 37% glycerin water at 37 degrees C. Hemolysis tests were performed utilizing a compact mock loop filled with fresh bovine blood in a left ventricular assist device (LVAD) condition at 37 degrees C. The KP101 achieved the LVAD conditions of 5 L/min and 100 mm Hg at 2,900 rpm; generated 10 L/min against 100 mm Hg at 3,200 rpm; 3 L/min against 90 mm Hg at 2,600 rpm; and 2 L/min against 80 mm Hg at 2,400 rpm. In addition, the pump efficiency during this experiment was 12.5%. The other Gyro pumps. that is, the C1E3, PI601, and PI701, in an LVAD condition require 1,600, 2,000, and 2,000 rpm, respectively. The KP101 produced a normalized index of hemolysis (NIH) value of 0.005 g/100 L. With regard to the NIH, the other Gyro pumps, namely the C1E3, PI601, and PI701 demonstrated 0.0007, 0.0028, and 0.004 g/100 L, respectively. The KP101 produced an acceptable pressure flow curve for a VAD. The NIH value was higher than that of other Gyro pumps, but is in an acceptable range.

Equipment Design↗

Involvement of dopamine D1-like receptors in mediating increases in protein secretion from rabbit lacrimal gland.

To identify and localize the dopamine receptor subtypes in rabbit lacrimal gland which mediate protein secretion, the effects were determined of different dopamine receptor subtype agonists, antagonists, and a beta adrenergic antagonist on this process. Protein secretion into the medium was quantified with the Bradford assay. Dopamine increased protein secretion between 10(-7) and 10(-4)M, and it could be maintained for a subsequent 80 min. The relatively selective D1-like receptor agonist, SKF-38393 (10(-4)M) had a similar effect which was suppressed by the D1-like receptor antagonist, SCH-23390. However, neither the D2-like receptor agonist, quinpirole (10(-4)M), nor the selective D2-like receptor antagonist, sulpiride (10(-4)M) altered either the basal level or the stimulated response to dopamine. The dopamine (10(-4)M)-elicited increases in protein secretion were completely suppressed in the presence of either 10(-4)M propranolol or 10(-4)M bretylium. Protein secretion in rabbit lacrimal gland is mediated by dopaminergic nerves through stimulation of the presynaptic D1-like receptor.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Molecular and functional characterization of the Rhodopseudomonas palustris no. 7 phosphoenolpyruvate carboxykinase gene.

The pckA gene, encoding the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK), was cloned by PCR amplification from the purple nonsulfur bacterium Rhodopseudomonas palustris No. 7. Sequencing of a 2.5-kb chromosomal SmaI-PstI fragment containing the structural gene revealed an open reading frame encoding 537 amino acids, homologous to known pckA genes. Primer extension analysis identified a transcriptional start site 72 bp upstream of the pckA initiation codon and an upstream sequence similar to sigma70 promoters. Studies of a pckA-lacZ gene fusion indicated that when cells were grown in minimal media with various carbon sources, such as succinate, malate, pyruvate, lactate, or ethanol, under both anaerobic light and aerobic dark conditions, the pckA gene was induced in log phase, irrespective of the carbon source. A R. palustris No. 7 PEPCK-deficient strain showed growth characteristics identical to those of the wild-type strain either anaerobically in the light or aerobically in the dark when a C4-dicarboxylic acid, such as succinate or malate, was used as a carbon source. These results indicate that in R. palustris No. 7, an alternative gluconeogenic pathway may exist in addition to PEPCK.

Amino Acid Sequence↗