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K Swenson

Publications and source records attributed to K Swenson.

8 recordsLinked to original sources
PubMed1997

The impact of microsurgical hepatic arterial reconstruction on the outcome of liver transplantation for congenital biliary atresia.

BACKGROUND: Hepatic artery thrombosis (HAT) after liver transplantation for biliary atresia (BA) is a serious complication that most often leads to retransplantation (re-OLT). The purpose of the present study was: (1) to identify risk factors associated with HAT and (2) to analyze the impact of recently introduced microsurgical hepatic arterial reconstruction (MHR) on the incidence of HAT, subsequent need for re-OLT, and patient survival. METHODS: A retrospective review of 194 patients transplanted for BA was performed. One hundred and sixty-six patients (group 1) underwent conventional arterial reconstruction and 28 (group 2) had MHR. RESULTS: Actuarial survival for patients with HAT was significantly worse than for patients without HAT at 1, 2, and 5 years (71%, 61%, and 57% versus 85%, 85%, and 85%, P = 0.0007). Stepwise logistic regression analysis revealed that the risk of HAT correlated best with the type of arterial reconstruction (P = 0.007) followed by pretransplant bilirubin concentration (P = 0.04) and the number of acute rejection episodes (P = 0.03). In group 1, 32 patients developed HAT (19%), and of these, 18 underwent re-OLT for HAT. No patient in group 2 developed HAT (P = 0.006 versus group 1). One-year actuarial patient survival was 81% in group 1 and 100% in group 2 (P = 0.02). CONCLUSIONS: In OLT for BA, (1) the predominant risk factor for HAT is the technique of arterial reconstruction, and (2) MHR markedly reduces the incidence of HAT and the need for re-OLT while improving patient survival.

Actuarial Analysis↗
PubMed1996

Skin graft tolerance across a discordant xenogeneic barrier.

Specific T-cell tolerance may be essential for successful xenotransplantation in humans. Grafting of thymectomized, T cell-depleted normal mice with xenogeneic fetal pig thymus and liver (FP THY/LIV) tissue results in the recovery of functional CD4 antigen-positive cells. We have tested T-cell tolerance by skin grafting. Donor-matched pig skin survived permanently (> 200 days), whereas allogeneic mouse skin was rapidly rejected. Nontolerant control mice rejected pig skin within 26 days. Both porcine and murine histocompatibility class IIhigh cells were detected in long-term thymus grafts, and T-cell repertoire analyses suggested that tolerance to both donors and recipients developed, at least in part, by intragraft clonal deletion. This study demonstrates the principle that tolerance, measured by the stringent criterion of skin grafting, can be induced across a widely disparate species barrier.

Animals↗
PubMed1996

Orthotopic liver transplantation for congenital biliary atresia. An 11-year, single-center experience.

OBJECTIVE: The authors analyze a single center's 11-year experience with 190 orthotopic liver transplants for congenital biliary atresia. SUMMARY BACKGROUND DATA: Hepatic portoenterostomy generally is the initial treatment for children with congenital biliary atresia. Despite multiple modifications of the hepatic portoenterostomy, two thirds of treated patients still develop recurrent cholestasis, portal hypertension, cholangitis, and cirrhosis. Therefore, the only hope of long-term survival in the majority of children with congenital biliary atresia is definitive correction with orthotopic liver transplantation. METHODS: The medical records of 190 consecutive patients undergoing orthotopic liver transplantation for congenital biliary atresia from July 1, 1984 to February 29, 1996 were reviewed. Results were analyzed via Cox multivariate regression analysis to determine the statistical strength of independent associations between pretransplant covariates and patient and graft survival. Actuarial patient and graft survival was determined at 1, 2, and 5 years. The type and incidence of post-transplant complications were determined, as was the quality of long-term graft function. The median follow-up period was 3.21 years. RESULTS: The liver grafts were comprised on 155 whole-organ, 24 reduced-size, and 11 living donor organs. Median pretransplant values for recipient age, weight, and total bilirubin were 1.4 years, 12.3 kg, and 13.8 mg/dL, respectively. One hundred sixty-four patients (86%) had undergone prior hepatic portoenterostomy. Eighty-seven patients (46%) were United Network for Organ Sharing (UNOS) status 1 or 2 at the time of liver transplantation. The majority (15/24, 62%) of reduced-size graft recipients were UNOS status I at the time of transplantation. One hundred fifty-nine patients (84%) received a single graft, whereas 31 patients required 37 retransplants. The 1, 2, and 5 year actuarial patient survival rates were 83%, 80% and 78% respectively, whereas graft survival rates were 81%, 77%, and 76%, respectively. Cox multivariate regression analysis demonstrated that pretransplant total bilirubin, UNOS status, and graft type significantly predicted patient survival, whereas recipient age, weight, and previous hepatic portoenterostomy did not. Current median follow-up values for total bilirubin and aspartate aminotransferase levels in the 154 surviving patients were 0.5 mg/dL and 34 international units/L, respectively. CONCLUSION: Long-term patient survival after orthotopic liver transplantation for congenital biliary atresia is excellent and is independent of recipient age, weight, or previous hepatic portoenterostomy. Optimal results are obtained in this patient population when liver transplantation is performed before marked hyperbilirubinemia, and when possible, using a living-donor graft.

Actuarial Analysis↗
PubMed1993

Motion perception in glaucoma.

PURPOSE: This study was performed to investigate motion perception in patients with glaucoma. METHODS: A random dot motion test was used to measure three aspects of central motion perception: minimum displacement threshold (Dmin), maximum displacement threshold (Dmax), and coherence threshold (signal to noise). Motion perception was assessed in 15 patients with primary open-angle glaucoma, 23 low-risk patients in whom glaucoma was suspected, and 24 age-matched normal subjects. RESULTS: Central motion perception was significantly impaired in patients with glaucoma; in particular, the Dmin was nearly twice that for the normal subjects (glaucoma mean, -0.27 +/- 0.24 log minutes of arc; normal mean, -0.56 +/- 0.13 log minutes of arc; F = 21.79, P < 0.001). Furthermore, Dmin values fell outside the normal range in 10 of the 15 patients with glaucoma, despite normal visual acuity and normal foveal perimetric thresholds. Coherence thresholds and Dmax did not discriminate between patients with glaucoma and normal subjects. Dmin was not correlated with any indices of perimetric sensitivity, and none of the tests of motion perception showed any abnormalities in patients in whom glaucoma was suspected. CONCLUSIONS: Central motion perception can be affected in glaucoma and may reflect preferential damage to larger retinal ganglion cells. Future work will measure Dmin in a larger population of patients with suspected glaucoma and those with glaucoma, and investigate peripheral motion perception in glaucoma.

Adult↗
PubMed1991

Maturation-specific polyadenylation: in vitro activation by p34cdc2 and phosphorylation of a 58-kD CPE-binding protein.

During Xenopus oocyte maturation, poly(A) elongation controls the translational recruitment of specific mRNAs that possess a CPE (cytoplasmic polyadenylation element). To investigate the activation of polyadenylation, we have employed oocyte extracts that are not normally competent for polyadenylation. Addition of cell lysates containing baculovirus-expressed cyclin to these extracts induces the polyadenylation of exogenous B4 RNA. The involvement of p34cdc2 kinase in cyclin-mediated polyadenylation was demonstrated by p13-Sepharose depletion; removal of the kinase from oocyte extracts with this affinity matrix abolishes polyadenylation activation. Reintroduction of cell lysates containing baculovirus-expressed p34cdc2, however, completely restores this activity. To identify factors of the polyadenylation apparatus that might be responsible for the activation, we employed UV cross-linking and identified a 58-kD protein that binds the B4 CPE in oocyte extracts. In polyadenylation-proficient egg extracts, this protein has a slower electrophoretic mobility, which suggests a post-translational modification. A similar size shift of the protein is evident in oocyte extracts supplemented with lysates containing baculovirus-expressed cyclin and p34cdc2. This size shift, which is reversed by treatment with acid phosphatase, coincides temporally with cyclin-induced polyadenylation activation. We propose that p34cdc2 kinase activity leads to the phosphorylation of the 58-kD CPE-binding protein and that this event is crucial for the cytoplasmic polyadenylation that occurs during oocyte maturation.

Animals↗
PubMed1982

Intraclassroom comparison of two arrangements for teaching profoundly mentally retarded children.

An intraclassroom (within-subject) comparison of two arrangements (one-to-one and small group) for teaching profoundly mentally retarded children was conducted. The dependent variables were teacher on-task time (the duration of minutes spent teaching behavioral objectives), the frequency of instructor turnaways per instructional minutes (the number of times the teacher left or turned away from the child being taught), the number of trials correct per child, and the number of objectives taught per child. A reversal design was used. Based on the first two variables, the one-to-one instructional arrangement appeared to be superior.

Child↗