PubMed Health⌕ Search

Biomedical subjects

K Urata

Publications and source records attributed to K Urata.

At least 19 recordsLinked to original sources
PubMed2005

Domino liver transplantation in living donors.

Domino liver transplantation (DLT) has been developed as a method to expand the donor pool. In living donors DLT, the prime concern is to avoid any disadvantage to the donor and the first recipient. Seven DLTs were performed among 211 patients who underwent living donor liver transplantation. The domino recipients included six with hepatocellular carcinoma and one with citrullinemia. The domino grafts were obtained from patients with familial amyloid polyneuropathy (FAP) including the left liver in three cases and the right liver in four. Among the seven domino recipients, a 64-year-old woman with advanced hepatocellular carcinoma died of lung metastasis. The other six domino recipients are alive without FAP symptoms. In living donor liver transplantation, because the vessels of the graft from the first donor are not long enough for anastomosis, the hepatic vessels must be left as long as possible when removing the liver from the FAP patients in order to ensure sufficient safety for vascular reconstruction. With careful decision making during the procedure, such as where to divide the vessels in the FAP patients, DLT may help address the shortage of liver grafts.

Amyloid Neuropathies, Familial↗
PubMed2004

Conversion from tacrolimus to cyclosporine microemulsion therapy in liver transplant recipients.

The calcineurin inhibitors cyclosporine and tacrolimus have distinct advantages and drawbacks. Therefore it is important to tailor their use to the patient's tolerance. In some patients, the need to ameliorate the adverse effects of tacrolimus may necessitate a switch to cyclosporine-based therapy. Rescue therapy with a cyclosporine microemulsion (Neoral)-based regimen for transplant patients intolerant of tacrolimus has been evaluated to assess the best method of switching and determine the initial and maintenance doses of Neoral in children and adults. Our aims were to evaluate not only these facets, but also the pharmacokinetics of Neoral in stable patients, including target 2-hour postdose blood concentrations (C2) of cyclosporine in liver transplant recipients. Eighteen liver transplant patients switched from tacrolimus to Neoral underwent a program of cyclosporine blood level monitoring. The conversions were conducted safely; the incidence of acute rejection episodes was low (11.1%). Statistical analysis showed that the C2 correlated with the area under the time-blood concentration curve of cyclosporine for 0 to 4 hours after dosing (R=0.970). We determined the maintenance doses of Neoral for pediatric and adult patients as well as the feasibility of C2 quantitated monitoring in liver transplantation.

Administration, Oral↗
PubMed2001

Long-term results of living-related donor liver graft transplantation: a single-center analysis of 110 transplants.

BACKGROUND: Difficulties of cadaveric donation and serious donor shortage have led to the development and popularization of living-related donor liver graft transplantation (LRLT). Because the history of this procedure is rather short, important aspects specific to this procedure have not been sufficiently documented. The objective of this study was to analyze a single center's 10-year experience with 110 LRLT in pediatric and adult patients with end-stage liver diseases. METHODS: The medical records of 110 consecutive patients who underwent LRLT were reviewed. The recipients were comprised of 72 children and 38 adults. The graft volume corresponded to 26-192% of the recipient's standard liver volume. The relationship between pretransplant covariates and patient and graft survival was analyzed. Actuarial patient/graft survival rates were determined at 1, 3, and 5 years. The type and incidence of posttransplant complications were analyzed, as was long-term graft function. RESULTS: The 1-, 3-, and 5-year actuarial patient and graft survival rates were 88%, 85%, and 85%, respectively. Log-rank test demonstrated that ABO-compatibility predicted patient survival rate, whereas patient age, underlying disease, patient's clinical status, donor-recipient relation, donor age, and graft volume/standard liver volume ratio did not. Long-term liver function remains excellent. All the donors have returned to normal daily lives with an uneventful course. CONCLUSIONS: LRLT is an efficacious procedure that provides excellent short-term and long-term survival. The indication criteria for both recipient and donor were legitimate in this series, except for transplant across ABO-incompatibility. Cautious expansion of this procedure may be justified under the situation of serious shortage of cadaveric donor.

Adolescent↗
PubMed2001

Effect of endotoxin-induced reactive oxygen species on sperm motility.

OBJECTIVE: To define the mechanism of infection-induced damage of sperm. DESIGN: The effect of lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) on sperm motility and its modification by scavengers were investigated. SETTING: Research laboratory of a university hospital. PATIENT(S): Normozoospermic semen samples were obtained from 37 healthy volunteers. INTERVENTION(S): The sperms were incubated in the presence of LPS with or without scavengers. MAIN OUTCOME MEASURE(S): Sperm motility was evaluated by a sperm quality analyzer (SQAIIB). ROS formation in semen samples was measured by a Berthold luminometer (LB953). RESULT(S): Motility of spermatozoa was decreased in the LPS-treated samples compared with that in the control groups. ROS was significantly higher in the LPS-treated groups than in the control groups. The addition of ROS scavengers restored the motility index and suppressed ROS production in the LPS-treated semen samples. CONCLUSION(S): These data suggest that endotoxin-induced excessive production of ROS is responsible for the decrease in sperm motility and that antioxidant therapy may be a therapeutic option for infertile men with bacterial genital tract infection.

Endotoxins↗
PubMed2001

Examination of electrostatic potential distribution across an implanted p-n junction by electron holography.

In the manufacture of semiconductor microelectronic devices, a p-n junction is formed usually by implanting a high concentration of impurity into a less heavily doped region and then heat annealing. A Si/Si p-n junction test sample has been made following the above practical process and thinned for electron holographic observation by using argon ion-milling. From the reconstructed phase image, the phase shift induced by potential drop across p-n junction can be seen clearly. To characterize quantitatively this potential drop, the mean inner potential V0 of silicon was measured precisely by electron holographic method. By measuring 25 different crystalline silicon spheres with diameter ranging from 40 to 170 nm, an average result of V0 = 12.16 +/- 0.83 V was obtained. By using this V0 value, a quantitative measurement yields the potential drop approximately 0.70 V, which is reasonably consistent with expected Si/Si junction parameter. The thickness of electric dead layer in depletion region produced from this measuring is approximately 20 nm on each sample surface.

Journal Article↗
PubMed2001

[Liver transplantation for liver metastases of colorectal cancer].

Because of the critical shortage of donor organs, liver transplantation for metastatic tumors should be reserved for patients in whom long-term survival is possible. Transplantation in patients with metastatic tumors from colorectal cancer has resulted only in short disease-free intervals, and palliation was achieved in only a few patients. In patients with symptomatic neuroendocrine tumors unresponsive to conventional therapy, on the other hand, reasonably good disease-free intervals and prolonged survival may justify liver transplantation.

Colorectal Neoplasms↗
PubMed2001

[Liver transplantation].

In western countries, liver transplantation in patients with hepatocellular carcinoma (HCC) has been performed with the use of grafts from brain dead donors, while in Japan this has begun being performed using partial liver grafts from living donors. This report describes our current results after liver transplantation for HCC and domino liver transplantation, which was introduced to resolve the organ shortage.

Carcinoma, Hepatocellular↗
PubMed2000

Regional cerebral blood flow in male schizophrenic patients performing an auditory discrimination task.

Regional cerebral blood flow (rCBF) was measured in 11 schizophrenic patients amid 10 normal controls, both at rest and while performing an auditory discrimination task. Single photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime was used for quantitative evaluation of rCBF. The schizophrenic patients showed greater rCBF in the temporal and parietal regions at rest than the controls, but no abnormalities were found in frontal perfusion. During task performance. on the other hand, the patients showed a reduced frontal rCBF. whereas there was no group difference in rCBF in the temporal and parietal regions. In addition, the left> right hemisphere asymmetries of rCBF observed in the controls during task performance were not present in the patients. although there was no group difference in hemisphere laterality in rCBF at rest. These findings suggest that the employment of a cognitive task for neuroimaging studies is useful for detecting abnormalities of brain activation. such as hypofrontality and altered hemisphere laterality. in patients with schizophrenia.

Adult↗
PubMed2000

Role of Kupffer cells in the survival after rat liver transplantation with long portal vein clamping times.

Applying the orthotopic rat liver transplantation (ORLT) model, postoperative survival has been shown to be mainly dependent on the portal vein clamping time (PVCT). It was hypothesized that prolonged intestinal congestion was responsible for the activation of Kupffer cells (KC) with overproduction of TNF, secondary to splanchnic endotoxin accumulation and release on reperfusion. The role of KCs was directly investigated in the context of long PVCTs by eliminating them (using liposome-encapsulated dichloromethylene diphosphonate), by preventing their activation (using a calcium channel blocker, nisoldipine) and by inhibiting TNF production (using thalidomide). Livers from different groups of rats were transplanted following 24-h cold preservation in the UW solution with long PVCTs (from 18-21 min). KCs depletion, preservation with nisoldipine and pretreatment with thalidomide significantly improved survival in conditions using long PVCTs. KC depletion and nisoldipine preservation had no effect on liver enzymes or pathological findings while lung injury was significantly improved. The present data confirm that, in the context of ORLT with long PVCTs, KCs are directly responsible for the systemic endotoxin-like shock syndrome and their effect is mediated through overproduction of TNF.

Adenosine↗
PubMed1999

Effects of portal vein clamping time on rat liver microcirculation following extended cold preservation and transplantation.

Orthotopic rat liver transplantation (ORLT) following extended cold preservation in University of Wisconsin (UW) solution has been shown to induce alterations of the hepatic microcirculation, mainly characterized by areas of no-reflow. The present study was performed to determine whether these alterations were related to the portal vein clamping time (PVCT), shown to be the main determinant of survival after ORLT. The hepatic microcirculation was evaluated using the multiple-indicator dilution curve (MIDC) technique after ORLT following 24-hour cold ischemia in UW solution. Two groups of rats were studied: one with PVCTs of less than 14 min (survival conditions) and one with PVCTs of more than 18 min (nonsurvival conditions). Four hours after ORLT, only long PVCTs were associated with small, but significant, nonperfused areas, about 10% of the liver not being perfused by water; however, in both survival and nonsurvival conditions, the sinusoidal sieving function was well-maintained in perfused areas. In addition, liver viability parameters and hepatocyte function were similarly and minimally altered. The hepatic microcirculation is minimally altered 4 h after ORLT following extended cold preservation in UW solution, whatever the survival condition. Although only found after long PVCTs, the low magnitude of areas of no-reflow should not be associated with lethal injury of the transplanted liver, a finding further supporting the concept that survival after ORLT following 24-hour cold preservation in UW solution is mainly influenced by extrahepatic factors.

Adenosine↗
PubMed1999

The relationship between auditory ERP and neuropsychological assessments in schizophrenia.

To clarify the cognitive significance of event-related potential (ERP) abnormalities in schizophrenia, we examined the relationships of amplitudes and latencies of ERP components with performance on neuropsychological tests in schizophrenic patients. Twenty patients underwent the Trail Making B Test (TM-B), which is sensitive to frontal lobe dysfunction, and the logical memory, verbal paired-association, and visual reproduction subtests of the Wechsler Memory Scale (WMS), which are sensitive to temporal lobe dysfunctions, and ERP recordings during performance of an oddball auditory discrimination task. Pearson product-moment correlations indicated that an increased P200 amplitude was correlated with poor performance on the TM-B, whereas a decreased P300 amplitude was correlated with poor performance on the verbal paired-association subtest of the WMS. These findings suggest that a P200 abnormality represents the frontal lobe dysfunction, and a P300 abnormality represents the left temporal lobe dysfunction in schizophrenia.

Adolescent↗
PubMed1999

[Effect of vasodilators on femoral-to-radial arterial pressure gradient after cardiopulmonary bypass].

In 57 adult patients undergoing valve replacement surgery or valve plastic surgery, pressure gradient between the femoral and radial artery was evaluated after cardiopulmonary bypass (CPB). During CPB, the rectal temperature was kept at mild or moderate hypothermia. Nitrates and prostaglandin E1 were administered in all patients during operation. Patients were divided into two groups; Group A of 31 patients who had history of hypertension and received some vasodilators up to the operation, and Group B of 27 patients who had no history of such medication. There was no difference in patient's characteristics, anesthetic time, CPB time and aortic cross clamping time between the two groups. There was a significant difference between the pre-CPB and post-CPB in hematocrit data. Systemic vascular resistance (SVR) decreased significantly from the pre-CPB level to the post-CPB level. There was no significant difference between Group A and Group B in SVR, but a higher femoral-to-radial artery pressure gradient was observed in Group A until the end of operation. Hypertension and the use of vasodilator change the tone of peripheral blood vessels and intensify femoral-to-radial artery pressure gradient after CPB.

Aged↗
PubMed1998

Concomitant caudate lobe resection as an option for donor hepatectomy in adult living related liver transplantation.

In this article, we describe a successful adult living related partial liver transplantation (LRLT) using the left lobe with the left-side caudate lobe (the Spiegel lobe and the left side of the paracaval portion). The size of the donor's left lobe was 29% of the recipient's standard liver volume and did not seem to meet our criteria for adult-to-adult LRLT. However, the donor had a thick left-side caudate lobe. The estimated volume of the left lobe with the left-side caudate lobe was 32%, which met our criteria for the adult recipient. The recipient's CT scan on day 87 after transplantation showed the preserved blood flow and no biliary congestion in the left-side caudate lobe, which suggests maintenance of lobe function. This procedure may be an option for adult-to-adult LRLT in which the donor has a thick left-side caudate lobe.

Adult↗
PubMed1998

P300 and the thought disorder factor extracted by factor-analytic procedures in schizophrenia.

BACKGROUND: In order to clarify the clinical significance of P300 as a biologic marker that can reflect schizophrenic symptomatology, many previous studies have evaluated the relationship of P300 with the symptoms on the basis of a positive/negative dichotomy, but yielded inconsistent conclusions. Such a dichotomy has been criticized as being too reductionistic. Recently, most studies with factor-analytic procedures have extracted some symptom factors outside this dichotomy. Therefore, it is important to examine associations of P300 with the symptom factors extracted by these statistical analyses. METHODS: In the present study, the amplitudes of P300 were measured by using an auditory oddball paradigm for 73 schizophrenics whose psychopathology was assessed with the Positive and Negative Syndrome Scale (PANSS). RESULTS: The principal component analysis of the PANSS items revealed five factors labeled the thought disorder, negative, hostile/excitable, delusional/hallucinatory, and depressive factors. The score for the thought disorder factor correlated negatively with the amplitude of P300 recorded at Pz T5, and T6, but that for the other factors did not. CONCLUSIONS: These findings suggest that the reduction of P300 amplitudes recorded at the midline parietal and bilateral temporoparietal regions may be one of the electrophysiologic indices representing the thought disorder clinically observed in schizophrenia.

Acoustic Stimulation↗
PubMed1998

Decreased survival in rat liver transplantation with extended cold preservation: role of portal vein clamping time.

Primary liver graft dysfunction is currently related to cold ischemia-reperfusion injury, although a wide survival range has been reported using 24-hour preservation in cold University of Wisconsin (UW) solution. We hypothesized that the portal vein clamping time (PVCT) played a more important role than cold preservation injury in the postoperative outcome. Rat liver transplantation was performed using different clamping times after 24-hour cold ischemia in the UW solution. Survival rates, plasma tumor necrosis factor (TNF), and nitrate/nitrite levels were examined. Subsequently, the effect of clamping time was evaluated on hepatocyte and sinusoidal endothelial cell (SEC) function using isolated perfused livers. Survival rate was directly related to clamping time length. Marked increases in TNF and nitrate/nitrite levels were found after surgery, particularly after long clamping times. In perfusion studies, the SEC function was already markedly altered after preservation alone and was not further modified by transplantation. By contrast, the hepatocyte function was moderately altered after transplantation, irrespective of clamping times, even when rats operated with long clamping times were in terminal conditions. In rats, 24-hour preservation in cold UW solution is not a severely compromising condition leading to primary liver nonfunction. Long PVCTs are associated with an endotoxemia-like syndrome more related to a warm intestinal ischemia than to cold ischemia injury of the liver.

Animals↗
PubMed1998

A case of primary non-Hodgkin's lymphoma of the uterine cervix treated by combination chemotherapy (THP-COP).

We present a case of primary non-Hodgkin's lymphoma of the uterine cervix, Ann Arbor stage IE. This 64-year-old multiparous Japanese woman showed markedly elevated serum levels of lactate dehydrogenase (LDH) and of soluble interleukin-2 receptor (sIL-2R) at the time of diagnosis. Combination chemotherapy was administered and consisted of pirarubicin, cyclophosphamide, vincristine sulfate, and prednisolone (THP-COP). After 3 courses of such therapy, the serum levels of LDH and of sIL-2R decreased within normal limits, and the patient achieved a complete remission.

Antineoplastic Combined Chemotherapy Protocols↗