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Y Yamaoka

Publications and source records attributed to Y Yamaoka.

At least 19 recordsLinked to original sources
PubMed1992

[The effects of centrifugal pump on liver support system with porcine liver perfusion].

The effects of vaneless centrifugal pump (Bio-pump P-80) on energy metabolism were studied, as compared with the roller pump, in an isolated porcine liver perfused with human blood for 6 hours. According to preliminary examination, flow rates were decided to 0.4, 0.8 ml/min/g in roller pump group, in Bio-pump pump group, respectively, not to increase more than 15 mmHg in initial portal pressure. During the perfusion, actual portal pressure was measured and circulatory resistance (portal pressure/flow rate) was calculated before perfusion and hourly after perfusion. Acetoacetate, beta-hydroxybutyrate, lactate and pyruvate, were measured at same times, from which values the ketone body ratio (acetoacetate/beta-hydroxybutyrate, KBR), reflecting the redox state of liver mitochondria, was calculated. In the Bio-pump group, in spite of its high flow, circulatory resistance was low at every hour during the perfusion. KBR was increased rapidly from 0.40 to 1.39, 2.59, 2.75, 2.38, 2.41, and 1.82 and lactate was decreased rapidly from 7.96 to 3.90, 1.77, 1.29, 1.33, 1.34, and 1.25 mmol/L at the respective hours after perfusion. There were significant differences at 2 and 4 hours after perfusion in KBR and after 2 hours of perfusion in lactate as compared with the roller pump group (p < 0.05). These results suggested that the Bio-pump is available for constant and high flow to the liver and helpful to elevate the mitochondrial NAD/NADH ratio (oxidized and reduced forms of free nicotinamide-adenine dinucleotides), leading to and enhancement of metabolic capacity of the perfused liver.

Adult↗
PubMed1992

Accumulation of allelic loss on arms of chromosomes 13q, 16q and 17p in the advanced stages of human hepatocellular carcinoma.

We examined loss of heterozygosity at 13 loci on 5 chromosomes in hepatocellular carcinomas (HCCs) from 56 patients. In 42 of these cases, regenerative nodules of liver cirrhosis were also analyzed. High frequencies of allelic losses were detected on chromosomes 13q (47%), 16q (40%) and 17p (64%), whereas losses on chromosome 4p and 11p were observed in less than 22% of cases in HCCs. In contrast, LOH was not detected on any loci in cirrhotic nodules. On chromosome 13q, the common region of allelic loss was mapped to the region including the retinoblastoma (RB) locus, by using 8 polymorphic probes. Furthermore, one case with 13q loss had an interstitial deletion of the RB gene, indicating the involvement of inactivation of the RB gene in hepatotumorigenesis. Losses were associated with portal-vein thrombosis or intrahepatic metastasis, increased tumor size, a poorly differentiated phenotype and clinical stage. Losses occurring together on 13q, 16q and 17p were significantly higher in patients in clinical stage IV or histologically poorly differentiated tumors, suggesting that the accumulation of allelic loss occurs in advanced tumors and that patients with multiple allelic losses may have a worse prognosis than those with a single loss.

Alleles↗
PubMed1992

Total vascular exclusion for hepatic resection in cirrhotic patients. Application of venovenous bypass.

Hepatic vascular exclusion with double venovenous bypass using a centrifugal force pump was used in major hepatic resections in eight patients with hepatocellular carcinoma combined with cirrhosis, and results were compared with those in four patients with hepatocellular carcinoma without cirrhosis and eight with metastatic tumors without cirrhosis among 521 patients undergoing liver resection. Concomitant resection of the retrohepatic inferior vena cava was performed in three of eight patients with cirrhosis and five of 12 patients without cirrhosis. All patients, except one with cirrhosis, tolerated major resection without any hemodynamic impairment, which is often observed in hepatic vascular exclusion without venovenous bypass. One patient, whose complete inflow occlusion period was 70 minutes, died of liver failure. In this patient, the recovery of the arterial ketone body ratio above 1.0 was delayed until 3 days after recirculation, whereas the ratio in the others recovered promptly. Postoperative complications such as increased bilirubin level, pleural effusion, and gastrointestinal tract bleeding were observed in seven of eight patients with cirrhosis compared with six of 12 without cirrhosis. Hepatic vascular exclusion is feasible even in cirrhotics as long as it is applied with venovenous bypass and is kept within the time limit of 60 minutes.

Adult↗
PubMed1992

A prolongation of hepatic vascular exclusion by in situ hypothermic perfusion in dogs.

In situ hypothermic hepatic perfusion was performed in dogs to explore whether the time limit of hepatic vascular exclusion could be prolonged. During hepatic vascular exclusion, hepatic hypothermic perfusion was performed via portal vein using various perfusates under active bypass from the portal vein and infrahepatic inferior vena cava area to the superior vena cava system. Dogs receiving hepatic hypothermic perfusion for 1 hour died when given Ringer's solution but survived more than 7 days when given Euro-Collins' and University of Wisconsin solutions. Although dogs tolerated 2 hours of hepatic hypothermic perfusion when give University of Wisconsin solution, all dogs died by 2 hours of hepatic hypothermic perfusion when given Euro-Collins' solution. The hepatic energy charge and arterial ketone body ratio of dogs that died were significantly lower than for those that survived. This suggests that the regimen of hepatic hypothermic perfusion with University of Wisconsin solution is able to maintain the energy metabolism of the liver under hepatic vascular exclusion for prolonged periods, hence, its possible clinical application.

Adenosine↗
PubMed1992

Bone metastases of hepatocellular carcinoma after liver resection.

Between January 1985 and July 1990, 323 cases of hepatocellular carcinoma underwent liver resection in our department. Bone metastases were found in 12 of these cases (3.7%). Bone metastases were mainly found in vertebral bone (58.3%) and pelvic bone (41.7%). The time interval to the development of bone metastasis after liver resection was closely related to the presence of intrahepatic metastasis and the stage at operation. In all cases, the initial clinical symptom was pain and/or motor disturbance. Radiotherapy was performed in 10 cases and transcatheter arterial embolization or surgery was performed in 4 cases. The pain or neurological symptoms improved with these therapies in all cases. Cumulative survival was 1 year in 74%, 2 years in 34%, and 3 years in 17%, respectively.

Adult↗
PubMed1992

Protective effect of a prostaglandin oligomer on liver mitochondria in situ: time-shared measurements of fluorescence and reflectance in the cold-preserved rat liver.

The protective effect of a new oligomeric derivative of prostaglandin B2, known as OC-5186, was evaluated using time-sharing spectrofluorometry in the cold-preserved rat liver. Experiments were divided into three groups: in group A, a 5000 ng dose of OC-5186 was administered via the peripheral vein, 1000 ng via the portal vein, and 200 ng/ml in University of Wisconsin (UW) solution; in group B, the OC-5186 dosage was ten times greater than that in group A; in group C (control group), liver procurement and storage were performed without OC-5186. At 0, 12, and 24 h after cold preservation at 4 degrees C, the liver was perfused for 30 min at 12 degrees C with oxygenized Krebs-Henseleit solution, after which the perfusate was switched to deoxygenized Krebs-Henseleit solution. Time sharing spectrofluorometry was used to follow NADH fluorescence at 450 nm with a 360-nm excitation wavelength, as well as the reflectance of cytochrome aa3 with 605 minus 620 nm from oxidation to reduction. Rate constants of NADH fluorescence and cytochrome aa3 reflectance were used as indices of integrity of the mitochondrial respiratory chain. In group C, the rate constant of NADH fluorescence decreased significantly (P < 0.05) from the control value of 8.31 +/- 0.21 x 10(-3) (sec-1) to 4.97 +/- 0.15 x 10(-3) and 5.58 +/- 0.16 x 10(-3) (mean +/- SEM) at 12 and 24 h after cold preservation, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Receiver operating characteristic (ROC) analysis of the ability of arterial ketone body ratio to predict graft outcome after liver transplantation--its sensitivity and specificity.

To evaluate the ability of arterial ketone body ratio (AKBR; acetoacetate/3-hydroxybutyrate) to predict graft prognosis after liver transplantation, the diagnostic value as a predictive index was compared between AKBR and conventional liver function tests using receiver operating characteristic (ROC) analysis. The ROC curves were determined for AKBR, GOT, GPT, total bilirubin, serum lactate level, and prothrombin time, all of which were measured on the 1st and 2nd postoperative days in 88 cases of liver transplantation. Comparisons of the areas under the ROC curves between AKBR and other tests revealed the significant superiority of AKBR to other tests in predicting graft death within 1 month after transplantation. The present study suggests that AKBR can be used as an accurate index to predict graft prognosis after liver transplantation.

Adolescent↗
PubMed1992

The role of enhanced mitochondrial phosphorylation in rat liver transplantation.

The effects of organ preservation on mitochondrial oxidative phosphorylation activity, adenylate hepatic energy charge, cytochrome content, and redox state of NAD+/NADH couple in rat liver transplantation were compared between a nonpreservation group and a preservation group with grafts preserved for 12 hr in Euro-Collin's solution. At 3 hr after transplantation, the energy charge in the preservation group decreased to 0.60 +/- 0.02 from the control value of 0.86 +/- 0.01, accompanied by a reduction of intramitochondrial redox state of NAD+/NADH couple. In contrast, in the nonpreservation group, the decrease in energy charge was minimally decreased to 0.79 +/- 0.04 due to the compensatory enhancement of mitochondrial oxidative phosphorylation activity. These results suggest that an enhanced mitochondrial ATP synthesis and a reduced intramitochondrial redox state are important factors affecting survival following rat liver transplantation.

Adenine Nucleotides↗
PubMed1992

Extent of ischaemia caused by hepatic vascular exclusion as evaluated in a canine model.

1. The difference in the extent of liver ischaemia between a hepatic vascular exclusion model and an inflow occlusion model were investigated by determining Indocyanine Green retention and hepatic mitochondrial redox state during 2 h of ischaemia in 10 mongrel dogs. The splanchnic venous bed and/or the infra-hepatic inferior vena cava were decompressed by pump-driven veno-venous bypass. 2. The Indocyanine Green retention test revealed that there was no hepatic blood flow in the hepatic vascular exclusion model during ischaemia (96.8 +/- 0.73% retention of the dye after 20 min), whereas hepatic blood perfusion was still present significantly in the inflow occlusion model (78.1 +/- 1.19% retention of the dye after 20 min) (P less than 0.01). 3. The mitochondrial redox potential of the liver in the dogs with hepatic vascular exclusion decreased immediately after the induction of ischaemia and remained fixed at extremely low levels. By contrast, in the dogs with inflow occlusion the redox potential decreased gradually after induction and was maintained significantly higher than that in dogs with hepatic vascular exclusion during 2 h of ischaemia (P less than 0.01). 4. It is concluded that the extent of liver ischaemia in the hepatic vascular exclusion model with pump-driven shunt is significantly different from that in the inflow occlusion model with shunt.

Animals↗
PubMed1992

A mixture of nucleosides and a nucleotide alters hepatic energy metabolism 24 hours after hepatectomy in rabbits.

The effect of administering a nucleoside-nucleotide mixture on hepatic energy metabolism was evaluated at 24 h after hepatectomy in rabbits that had had 70% of their livers removed. After hepatectomy, animals were administered continuous intravenous infusion of 2 mL/(kg body wt-h) of 9 g/L NaCl (Group S), 5.99 mmol/L nucleoside-nucleotide mixture (Group N1) or 11.98 mmol/L nucleoside-nucleotide mixture (Group N2). At 24 h after hepatectomy, the hepatic adenylate energy charge in Group S (0.83 +/- 0.01, mean +/- SEM) was significantly lower than that before hepatectomy (0.90 +/- 0.01). By contrast, the values in Groups N1 and N2 after hepatectomy (0.74 +/- 0.04 and 0.73 +/- 0.04, respectively) were significantly lower than that in Group S. The hepatic mitochondrial phosphorylation rate before hepatectomy was 46.40 +/- 4.88 nmol ATP/(mg mitochondrial protein-min). After hepatectomy, significantly greater values were observed in Groups N1 and N2 (69.53 +/- 7.20 and 63.31 +/- 6.11, respectively), yet those values were less than observed in Group S (109.14 +/- 4.80). These results suggest that the nucleoside-nucleotide mixture suppressed the enhancement of hepatic mitochondrial phosphorylative activity at a time when hepatic adenylate energy charge is compromised. Such enhancement is needed to compensate for the increased energy expenditure due to surgical intervention.

Adenosine Diphosphate↗
PubMed1992

An appraisal of pediatric liver transplantation from living relatives. Initial clinical experiences in 20 pediatric liver transplantations from living relatives as donors.

The authors performed 20 liver transplantations from living related donors between June 1990 and July 1991. The 20 pediatric patients (14 biliary atresia, two Budd-Chiari syndrome, one liver cirrhosis after hepatitis C viral infection (HCV hepatitis), 1 progressive intrahepatic cholestasis, 1 liver cirrhosis, 1 protoporphyria) were transplanted with 11 left lobes, eight left lateral segments, and one right lobe. The choice of donors was restricted to the parents of the recipients. The immunosuppressive treatment consisted of FK 506 and steroids. Seventeen recipients are alive, 15 of whom are well and at home. Two recipients, who underwent emergency transplantation, died of postoperative complications. Another recipient died of accidental asphyxia at 6 months after the transplantation. All 20 donors had uneventful postoperative courses and were able to resume their normal social lives. The arterial ketone body ratio (AKBR) increased to above 1.0 within 2 days after the transplantation in all cases. Relatively mild rejection episodes were encountered in only two cases transplanted with ABO-compatible grafts, and these were treated successfully with steroids and FK 506.

Adolescent↗
PubMed1992

Maintenance of liver graft viability in the state of brain death. Synergistic effects of vasopressin and epinephrine on hepatic energy metabolism in brain-dead dogs.

The influence of vasopressin and epinephrine on hepatic energy metabolism in the state of brain death was assessed by measuring arterial ketone body ratio (AKBR) and hepatic energy charge (EC) in brain-dead dogs. Mean arterial blood pressure (MABP) was significantly decreased from 125.5 +/- 5.5 to 53.4 +/- 1.7 mmHg after complete brain death (P less than 0.01). In the control group AKBR and EC were maintained at near the normal values thereafter, despite marked hypotension. Combined administration of vasopressin and epinephrine sustained AKBR normally and improved MABP above 90 mmHg (P less than 0.01). EC was also maintained within the normal range at 5 hr after initiation of administration of the drugs. By contrast, vasopressin or epinephrine alone maintained AKBR and EC at near the normal values, but improved MABP just slightly to around 60 mmHg (P less than 0.01). As for the volume control, the urinary output was significantly smaller in the vasopressin and epinephrine-treated group than in the control group (P less than 0.05). It is suggested that combined administration of vasopressin and epinephrine has a synergistic effect in improving the hemodynamics and maintenance of the energy status of the liver. This regimen is recommended as a good one for maintaining potential liver donors in the state of brain death.

Adenine Nucleotides↗
PubMed1992

Beneficial effect of combined 3,5,3'-triiodothyronine and vasopressin administration of hepatic energy status and systemic hemodynamics after brain death.

The influence of combined replenishment of L-3,5,3'-triiodothyronine (T3) and vasopressin (antidiuretic hormone [ADH]) on both hepatic metabolism and systemic hemodynamics was assessed in brain-dead dogs. Arterial ketone body ratio (AKBR) was measured as a parameter of hepatic metabolism, which reflects the redox state (free nicotinamide adenine dinucleotide/reduced nicotinamide adenine dinucleotide) of liver mitochondria. Mean arterial blood pressure (MAP) was significantly decreased from 110.4 +/- 3.8 to 44.4 +/- 1.7 mmHg, at 1 hr after completion of brain death (P less than 0.01). In the control group AKBR was maintained thereafter at near control value of 1.0 with a significant decrease in serum lactate concentration in spite of marked hypotension. T3 infusion at a rate of 1 microgram/kg/hr elevated the AKBR but did not elevate MAP. Vasopressin infusion at a rate of 0.1 U/kg/hr sustained AKBR and elevated MAP significantly at 1 hr after administration but tended to decrease thereafter. Combined administration of T3 and ADH elevated the AKBR to about 2.0, and MAP was restored to near-normal level. Other parameters such as glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactic dehydrogenase, reflecting liver cell injury and serum creatinine, and blood urea nitrogen as renal function, were maintained within normal range. These results indicate that combined T3 and vasopressin administration has a beneficial synergistic effect on both hepatic energy metabolism and systemic hemodynamics without any detrimental influence to other conventional parameters. Therefore, it is suggested that this combined administration may contribute to the management of potential multiorgan donors.

Animals↗
PubMed1992

The introduction of microvascular surgery to hepatic artery reconstruction in living-donor liver transplantation--its surgical advantages compared with conventional procedures.

Microvascular surgery for the reconstruction of the graft artery has been used since the 8th case in our series of 14 liver transplantations using living-related donors, and the clinical results have been compared between the first seven cases (the Loupe group) and the last seven cases (the Micro group). Seven arteries in 7 grafts were reconstructed with the use of loupe magnification in the Loupe group, while 8 arteries in 7 grafts were anastomosed with microscopic techniques in the Micro group. Statistically, there was no difference between the two groups in general background, including age, body weight and primary disease of the recipient, and in medical and surgical factors possibly relating to postoperative thrombosis of the hepatic artery. In two cases in the Loupe group, one or two additional reconstructions were necessary to obtain sufficient blood flow, while 8 arteries were anastomosed in the Micro group without any arterial complication in the postoperative period. There was no difference in time required for completing the arterial reconstruction (45.1 +/- 18.1 min in the Loupe versus 44.4 +/- 6.9 min in the Micro [mean +/- SEM]). Postoperative ultrasonic Doppler duplex study demonstrated a temporary decrease in the arterial flow in 2 cases of the Loupe group, and partial thrombosis of the artery was suspected. Additionally there were two episodes of hepatic artery thrombosis in 1 case of the Loupe group, in which emergent revision for thrombectomy and reanastomosis was performed at the first episode. This illustrated the higher incidence of arterial complications in the Loupe group compared with the Micro group (4 episodes/7 arteries in the Loupe versus 0/8 arteries in the Micro, P less than 0.05). In the present series there were no graft failures or arterial complications in the three deaths in the series. The clinical improvements achieved by microvascular surgery in living-donor liver transplantation suggest an alternative technical strategy for dealing with problematic arterial reconstruction in adult liver transplantation.

Child↗
PubMed1992

Analyses of the risk and operative stress for donors in living-related partial liver transplantation.

Operative risk and stress were analyzed in 28 parent-donors whose children received partial liver transplantations at the Second Department of Surgery, Kyoto University Hospital between June 1990 and December 1991. Graft-harvesting operations were classified into three types: left lobectomy (group L, n = 12), left lateral segmentectomy (group S, n = 15), and right lobectomy (n = 1). Since donor safety is a primary concern, great care was taken to minimize potential damage to the remaining lobes of the donor liver as well as the graft liver by avoiding stressful maneuvers such as hepatic vascular clamping during the transection of the hepatic parenchyma. In all cases the arterial ketone body ratio, which reflects the hepatic mitochondrial redox potential, was maintained at over 0.7 throughout the donor operation as well as postoperatively. There was no significant difference in the postoperative RBC, WBC, serum GOT, and total bilirubin between groups L and S, although the abnormalities exhibited by the single right lobectomy case tended to be larger and more prolonged. All cases were within the range acceptable for immediate discharge, and all donors of groups L and S were subsequently discharged within 14 days without any postoperative complications. The single right lobectomy donor was discharged on POD17 because of transient slight icterus, which is the only postoperative complication encountered in this series thus far. The present analyses would indicate that the risk and operative stress to the donor in living-related partial liver transplantation can be minimal when the left lobe or left lateral segment of the liver is used for the graft.

Aspartate Aminotransferases↗
PubMed1992

Effects of fatty acids, fatty amines and propylene glycol on rat stratum corneum lipids and proteins in vitro measured by fourier transform infrared/attenuated total reflection (FT-IR/ATR) spectroscopy.

Fourier transform infrared/attenuated total reflection (FT-IR/ATR) spectroscopy was used to examine the effect of fatty acids, fatty amines and propylene glycol (PG) on the molecular mobility of rat stratum corneum lipids and keratinized proteins, using a hydrophobic solute, indomethacin, and a polar solute, 5- and 6-carboxyfluorescein (CF). Treatment of the skin with either oleic acid or oleylamine resulted in significant CH2 C-H asymmetric stretching band shifts and broadening. The extent of spectral alteration varied with the chemical structure of the penetrant. The penetrants increased the lipophilic indomethacin flux and shortened the lag times through the skin in vitro. The plot of frequency changes vs. indomethacin flux or lag time demonstrated a linear relationship, thus indicating that spectral alteration in CH2 C-H stretching regions of stratum corneum lipids may provide a reliable index for characterizing penetrants. The data also showed that the hydrophilic group which attached to the CH2 group in the penetrant molecules did not play a part in the membrane permeability enhancing action. Oleic acid and oleylamine appeared to induce a conformational alteration of the keratinized proteins from alpha-helix to beta sheet. Such alteration was also observed with PG treatment. Accumulation of CF was significantly increased by the PG pretreatment of the skin, thus suggesting that PG-induced protein conformational changes could be related to the enhancement of CF accumulation.

Amines↗
PubMed1992

Destabilization of whole skin lipid bio-liposomes induced by skin penetration enhancers and FT-IR/ATR (Fourier transform infrared/attenuated total reflection) analysis of stratum corneum lipids.

Whole skin lipid bio-liposomes (skin bio-liposomes), in size ranging from 2 to 8 microns, were prepared by a reverse phase evaporation technique using rat full thickness skin. Leakage of an encapsulated fluorescence probe, ANTS (delta-amino-1,3,6-naphthalene-trisulfonate), was measured by adding transdermal penetration enhancers (penetrants) into the medium where the skin bio-liposomes were present. Oleylamine induced a fast release of ANTS from the liposomes compared to lauryl-amine which showed a weak action. With these penetrants, the degree of ANTS release from the prepared bio-liposomes was found to correlate well with the results of frequency changes in the CH-asymmetric stretching band near 2920 cm-1 in the rat stratum corneum. The penetrant which caused relatively strong leakage of ANTS induced the significantly large shift of the peak toward the higher wave-numbers due to the perturbation in the structure of lipids of the stratum corneum. The skin bio-liposomes prepared from the rat full thickness skin could be useful in evaluating the penetrants.

Amines↗