This study examined the influence of background noise on the localization of lead-lag noise-burst pairs and on echo threshold for the same stimuli. Experiments were conducted in an anechoic chamber with a leading stimulus delivered from a loudspeaker at 45 degrees to the right of center and a lagging stimulus from 45 degrees left. Lead and lag stimuli were 4-ms bursts of Gaussian noise. In experiment 1, with lead and lag at equal levels and the lag delay fixed at 2 ms, the perceived location of the image produced by the lead-lag stimulus was estimated from subjects' left/right judgments relative to bursts from a "comparitor" loudspeaker whose position could be adjusted. In experiment 2, the dominance of the leading burst on perceived location was measured by determining the increase in level of the lagging burst necessary to produce an image estimated to be centered at 0 degree azimuth. Experiment 3 was concerned with echo threshold. Subjects reported whether or not they heard a sound in the vicinity of the lagging loudspeaker as the lag-burst delay was varied. In all three experiments, data were obtained for four to five stimulus levels in quiet and for three levels of background white noise from a loudspeaker at 180 degrees. The results revealed a substantial weakening effect of background noise on the precedence effect in experiments 2 and 3, and a nonsignificant effect in experiment 1.

Adult↗

PubMed1998

DBF2 protein kinase binds to and acts through the cell cycle-regulated MOB1 protein.

The DBF2 gene of the budding yeast Saccharomyces cerevisiae encodes a cell cycle-regulated protein kinase that plays an important role in the telophase/G1 transition. As a component of the multisubunit CCR4 transcriptional complex, DBF2 is also involved in the regulation of gene expression. We have found that MOB1, an essential protein required for a late mitotic event in the cell cycle, genetically and physically interacts with DBF2. DBF2 binds MOB1 in vivo and can bind it in vitro in the absence of other yeast proteins. We found that the expression of MOB1 is also cell cycle regulated, its expression peaking slightly before that of DBF2 at the G2/M boundary. While overexpression of DBF2 suppressed phenotypes associated with mob1 temperature-sensitive alleles, it could not suppress a mob1 deletion. In contrast, overexpression of MOB1 suppressed phenotypes associated with a dbf2-deleted strain and suppressed the lethality associated with a dbf2 dbf20 double deletion. A mob1 temperature-sensitive allele with a dbf2 disruption was also found to be synthetically lethal. These results are consistent with DBF2 acting through MOB1 and aiding in its function. Moreover, the ability of temperature-sensitive mutated versions of the MOB1 protein to interact with DBF2 was severely reduced, confirming that binding of DBF2 to MOB1 is required for a late mitotic event. While MOB1 and DBF2 were found to be capable of physically associating in a complex that did not include CCR4, MOB1 did interact with other components of the CCR4 transcriptional complex. We discuss models concerning the role of DBF2 and MOB1 in controlling the telophase/G1 transition.

Alleles↗

PubMed1998

Lymphoproliferative disorder after liver transplantation.

Lymphoproliferative disorder (LPD) is a well recognized complication of solid organ transplantation. It is associated with Epstein-Barr virus (EBV) infection and is often a fatal complication of immunosuppression. We report a 2.5-year-old boy who developed LPD presenting as small bowel lymphoma after liver transplantation. The patient had intermittent fever after transplantation and reactivation of latent EBV infection was documented by pre- and posttransplant serologic tests. About 5 months after his liver transplantation, the patient had sudden onset of abdominal pain and emergency laparotomy was performed for peritonitis. He proved to have multiple small bowel perforations caused by B cell lymphoma and died of multiple organ failure 9 days after operation, despite aggressive treatment and stopping immunosuppressive agents. We conclude that prevention of overimmunosuppression in pediatric recipients after liver transplantation and early detection and treatment of LPD are important to decrease this often-fatal complication.

Child, Preschool↗

PubMed1998

Intraoperative Doppler ultrasound in liver transplantation.

The purpose of this study was to determine the utility of intraoperative Doppler ultrasound for the diagnosis and reduction of the vascular complications in liver transplantation. This study included 19 pediatric and 5 adult patients. In the pediatric group, 12 patients received living related liver transplantation (LRLT), two splitting liver transplantation (SLT), three reduced-size liver transplantation (RLT) and two full-size pediatric liver transplants (FPLT). The hemodynamics and waveform of the hepatic vein, portal vein and hepatic artery were evaluated by intraoperative Doppler ultrasound (US) after reperfusion of the graft. Unsatisfactory hemodynamics was identified in nine cases, including decrease hepatic venous flow (6-9 cm/s) with non-pulsative flat waveform (adults, n = 2 and LRLT, n = 2); portal vein thrombosis (LRLT, n = 1); decrease portal flow (8 mL/min/kg) (LRLT, n = 1); occlusion of the portal vein (SLT, n = 1); poor arterial flow with dampened artery waveform (FPLT, n = 2). These abnormalities were all successfully re-reconstructed by surgical procedures and achieved a graft survival rate of 100%. Two late vascular complications including hepatic venous thrombosis and recurrent portal vein stenosis with splenorenal shunt were discovered 1 month later. They were treated effectively by surgical thrombolectomy and percutaneous balloon dilatation and metallic coils embolization respectively. Three patients died of non-vascular complications and all patients who underwent LRLT survived with a resultant 87.5% overall survival rate. In conclusion, intraoperative Doppler US is efficient in detecting abnormal hepatic hemodynamics, which permits early intervention and hence a better prognosis for the patients. Re-reconstructive procedures were monitored closely under Doppler US guidance until proper flow and wave-form were established. This reduces post-transplant vascular complications and thereby eliminates the likelihood of a lethal complication that might call for re-transplantation.

Adolescent↗

PubMed1998

Post-transplant changes of segment 4 after living related liver transplantation.

The purpose of this study was to evaluate the outcome of the medial segment of the graft after living related liver transplantation (LRLT). Of the 12 pediatric recipients who underwent LRLT, 2 received whole left liver graft, 1 left lateral segment graft, and 9 extended left lateral segment grafts. The hepatic veins of the donor were reviewed and the volume of the medial segment and left lateral liver was measured before and 6 months after liver transplantation. The flow velocity and direction of the portal vein in the medial segment graft was also evaluated by Doppler ultrasound. The grafted livers of all recipients showed a substantial increase in volume of 9-120% 6 months after LRLT. For the left lateral segment, an increase in volume was found in all cases ranging from 21 to 245%. For the medial segment, volume increases of 5-48% were found in seven cases with normal hepatopetal flow detected inside the segment 4 intrahepatic portal vein. In four cases, the partial medial segment graft of the extended left lateral liver graft decreased in volume from 33 to 69%. Among these four cases, slow flow (n = 2) and hepatofugal flow (n = 1) were also detected in the intrahepatic portal vein of the medial segment. Mapping of the tributary of the hepatic veins of the graft revealed inadequate venous drainage of the partial segment 4 graft, which may be considered as the cause of the atrophic change of the partial segment 4 graft. In conclusion, different regenerative rates between the left lateral segment and the medial segment were noted, with a greater rate in the left lateral segment. The venous drainage of the medial segment is of primary concern in the determination of the outcome of the regeneration. Atrophic change occurs when inadequate hepatic venous drainage is encountered. Therefore, if an extended left lateral liver graft is required, the corresponding draining veins of the partial medial segment must be preserved. Otherwise, whole left liver or left lateral segment graft would be a better choice.

Blood Flow Velocity↗

PubMed1997

DBF2, a cell cycle-regulated protein kinase, is physically and functionally associated with the CCR4 transcriptional regulatory complex.

CCR4, a general transcriptional regulator affecting the expression of a number of genes in yeast, forms a multi-subunit complex in vivo. Using the yeast two-hybrid screen, we have identified DBF2, a cell cycle-regulated protein kinase, as a CCR4-associated protein. DBF2 is required for cell cycle progression at the telophase to G1 cell cycle transition. DBF2 co-immunoprecipitated with CCR4 and CAF1/POP2, a CCR4-associated factor, and co-purified with the CCR4 complex. Moreover, a dbf2 disruption resulted in phenotypes and transcriptional defects similar to those observed in strains deficient for CCR4 or CAF1. ccr4 and caf1 mutations, on the other hand, were found to affect cell cycle progression in a manner similar to that observed for dbf2 defects. These data indicate that DBF2 is involved in the control of gene expression and suggest that the CCR4 complex regulates transcription during the late mitotic part of the cell cycle.

Cell Cycle↗

PubMed1997

Free tissue transfer for leg reconstruction in children.

Twenty-five free tissue transfers for reconstruction after lower limb trauma or release of scar contractures were performed in 23 children over an 8-year period. The ages ranged from 2 to 14 years (mean 7.1 years). Fourteen (61%) patients had major associated injuries. The reconstruction sites were all in the distal leg. The overall vascular success rate was 96%. Three patients underwent re-explorations because of vascular insufficiency. One flap failed and two were salvaged. The causes of vascular complications were considered to be inadequate debridement of an avulsed vessel, venous kinking and inadequate protection of the vascular pedicle. The three cases with vascular insufficiency were children with associated injuries on the ipsilateral leg proximally. Postoperative complications were not uncommon (28%). Six of the seven complications occurred in patients with major associated injuries. The mean follow-up was 57 months. Long-term problems such as a limping gait, frequent flap ulcers, toe contracture or a bulky flap were common. Our results suggest that free tissue transfer is reliable and safe for the reconstruction of major leg injuries in children. Associated injuries proximal to the reconstructed defects on the ipsilateral leg predispose to more vascular complications. Since postoperative complications and long-term morbidity are common in children, special precautions should be taken with the preoperative assessment, planning, execution of surgery and postoperative care to achieve better results.

Accidents, Traffic↗

PubMed1997

Plasma antioxidant vitamins, chronic hepatitis B virus infection and urinary aflatoxin B1-DNA adducts in healthy males.

Epidemiological evidence indicates that aflatoxin B1 (AFB1) intake is associated with an increased risk of hepatocellular carcinoma (HCC). The hepatocarcinogenesis is initiated by covalent binding of AFB1 to cellular DNA. To determine whether nutritional factors and hormonal status may influence the binding of AFB1 to hepatic DNA, a cross-sectional study was performed on a total of 42 male asymptomatic hepatitis B surface antigen (HBsAg) carriers and 43 male non-carriers in a cohort study on the multistage development of HCC in Taiwan. The major AFB1-DNA adduct in vivo, AFB1-N7-guanine, was measured by high-performance liquid chromatography in urine. Urinary AFB1-N7-guanine was detectable in 40% of the subjects. HBsAg carriers had a higher detection rate of urinary AFB1-DNA adducts than non-carriers and the difference was statistically significant after multivariate adjustment. After taking into account the total AFB1 urinary metabolite level, chronic HBsAg carrier status, and other potential confounders, plasma levels of cholesterol, alpha-tocopherol, and alpha- and beta-carotene were positively associated with the detection rate of the AFB1-DNA adducts in a dose-dependent manner, whereas plasma lycopene level was inversely related to the presence of the adducts in urine. The association of urinary AFB1-DNA adducts with the plasma levels of cholesterol, alpha-tocopherol, lycopene, and alpha- and beta-carotene was observed at both low and high exposure levels of AFB1. There was a synergistic interaction of plasma alpha-tocopherol with alpha- and beta-carotene on the adduct levels. No association with the adducts was found for plasma levels of retinol and testosterone. This study demonstrated different associations of antioxidant vitamins with AFB1-DNA adduct formation. The data consistent with our previous finding in cultured woodchuck hepatocytes that alpha-tocopherol and beta-carotene enhanced AFB1-DNA adduct formation suggest that prospective investigation of the relationship between plasma micronutrients and risk of AFB1-related HCC is warranted.

Adult↗

PubMed1997

Toe-to-hand transfer for traumatic digital amputations in children and adolescents.

In the period from July of 1990 to August of 1994, 45 toe or toe tissue transfers were performed in 28 children and adolescents with traumatic amputation of digits. The average age at the time of transfer was 12 years (range, 3 to 16 years), and the median age was 10 years. The methods of reconstruction included transfer of 6 trimmed great toes, 2 great toe pulps, 24 second toes, 1 vascularized metatarsophalangeal joint from the second toe, 2 third toes, 4 combined second and third toes. and 1 combined third and fourth toes. All of the transferred toes, except one second toe, ultimately survived. Exploration and reanastomosis were required in three cases owing to arterial insufficiency. Partial pulp loss occurred in two digits. Follow-up ranged from 1 to 5 years (average, 3 years). Bony union occurred uneventfully in all patients. Two-point discrimination averaged 5 mm (static) and 6 mm (moving). Active range of the motion averaged 69, 38, and 13 degrees at the metaphalangeal proximal interphalangeal and distal interphalangeal joints of the reconstructed fingers, respectively, and 15 degrees at the interphalangeal joint of the reconstructed thumbs. None of the children required subsequent tenolysis. Pulp plasty was performed in nine digits in seven patients. Radiologically, the transferred phalanges showed the some growth as the non-transferred ones. Trimming the great toe before transfer did not result in premature physeal closure or growth retardation. The donor foot maintained a satisfactory appearance. None of the patients complained of difficulty in running or jumping. Toe-to-hand transfer in children, performed meticulously, can provide a valuable option for reconstruction of traumatic digit loss.

Adolescent↗

PubMed1997

Reconstruction of a large thoracoabdominal wall defect with a flow-through forearm flap and a latissimus dorsi-groin flap.

We report a case of a 45-year-old man with a recurrent, large, invasive dermatofibrosarcoma protuberans over the left lower chest and abdomen. Wide surgical excision of the tumor created a major thoracoabdominal wall defect. Wound coverage was achieved by using a flow-through forearm flap and an inferiorly based latissimus dorsi-groin flap. Follow-up at 1 year revealed no local recurrence or herniation.

Abdominal Muscles↗

PubMed1997

Living related donor liver transplantation.

Living related liver transplantation (LRLT) has been developed in response to the paediatric organ donor shortage. According to the International Living Donor Registry, 521 transplants had been performed in 515 patients between December 8 1988 and January 19 1996 in 30 centres worldwide. The overall actuarial patient and graft survival rates were 82.7 and 80%, respectively. Between June 17 1994 and November 30 1996, the authors performed 11 LRLT at the Chung Gung Memorial Hospital. The living donors consisted of 10 mothers and one father. The mean graft weight was 303 g and the mean graft recipient weight ratio was 2.2%. Donor hepatectomy was performed without vascular inflow occlusion. The intra-operative blood loss ranged from 30 mL to 120 mL with an average of 61 mL, and blood transfusion was not required in all donors both intra-operatively and during the postoperative period. Underlying diseases of the recipients were biliary atresia (n = 10) and glycogen storage disease (n = 1). The mean graft cold ischaemia time was 106 min, the mean second warm ischaemia time was 51 min and the mean interval between portal and arterial reperfusion was 81 min. The initial LRLT results were promising with all donors having been discharged without complication. The recipients experienced a few complications, all of which were manageable with early intervention. All 11 recipients are alive and well. These are encouraging results and the authors hope to expand the use of live donors for liver transplantation to cope with demand.

Adolescent↗