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Biomedical subjects

K Swenson

Publications and source records attributed to K Swenson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Liver transplantation for adult polycystic liver disease.

Polycystic liver disease, commonly associated with polycystic kidney disease, can result in massive hepatomegaly and debilitating symptoms. Surgical intervention for symptomatic polycystic liver disease has been associated with significant morbidity and inconsistent long-term palliation; it is more appropriate in patients with a single dominant cyst or cysts which is/are confined to one lobe. At our institution, nine patients have undergone orthotopic liver transplantation for symptomatic hepatic cysts with excellent long-term results and minimal morbidity and mortality. Surgical candidates were selected based on severe limitations in daily activities and on sequelae of hepatic cystic involvement. Other factors considered were the extent and pattern of hepatic cystic disease, the degree of hepatic and renal dysfunction, and prior surgical intervention. Three patients (33%) required combined liver and kidney transplantation because of renal cystic involvement with renal insufficiency. The one-year survival rate was 89% with excellent symptomatic relief and improved quality of life in all the surviving patients. One death occurred in a significantly malnourished 62-year-old female. Complications included one case each of hepatic artery thrombosis requiring retransplantation, biliary leak necessitating biliary reconstruction, and postoperative bleeding requiring re-exploration. The mean hospital stay was 23 days and the mean intraoperative blood transfusion requirement was 18 units. Our experience demonstrates that appropriately selected patients with extensive hepatic involvement with adult polycystic liver disease can have an excellent outcome with transplantation, with morbidity comparable with other surgical options.

Adult↗
PubMed1998

Overexpression of pp60c-src elicits invasive behavior in rat colon epithelial cells.

BACKGROUND & AIMS: Src activation is reported as an early event found in preneoplastic colonic adenomas and in 70% of colon carcinomas. The aim of this study was to identify the biological consequences of c-src overexpression in rat colon epithelial cells. METHODS: Introduction and overexpression of c-src in an immortalized rat colon epithelial cell line was achieved using lipofection. Transfectants were tested for changes in growth and cell behavior using different in vitro assay systems. RESULTS: Colon epithelial cells overexpressing c-src showed the ability to form microcolonies in soft agar without acquiring tumorigenic potential. In in vitro assays, c-src transfectants displayed a gain of invasive potential through Matrigel without an accompanying change in migrational ability. No discernible qualitative changes were observed in the phosphotyrosyl protein profile between c-src and v-src transfectants. Assessment of the cadherin/catenin status in these cells revealed an intact, functional complex with no detectable tyrosine phosphorylation of different components of the complex. CONCLUSIONS: Overexpression of c-src in an immortalized rat colon epithelial cell line does not elicit full neoplastic transformation but enhances anchorage-independent growth and confers invasion capability. Increased invasion through Matrigel was not linked to inactivation of the cadherin complex in c-src transfectants.

Animals↗
PubMed1998

Long-term results of pediatric liver transplantation: an analysis of 569 transplants.

OBJECTIVE: To analyze a single center's 13-year experience with 569 pediatric orthotopic liver transplants for end-stage liver disease. SUMMARY BACKGROUND DATA: Despite advances in medical therapy, liver replacement continues to be the only definitive mode of therapy for children with end-stage liver disease. Innovative surgical techniques and improved immunosuppression have broadened the application of liver replacement for affected children. However, liver transplantation in the child remains challenging because of the scarcity of donor organs, complex surgical technical demands, and the necessity to prevent long-term complications. METHODS: The medical records of 440 consecutive patients younger than 18 years of age undergoing orthotopic liver transplantation for end-stage liver disease from March 20, 1984, to November 15, 1997, were reviewed. Results were analyzed using 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 rates were determined at 1, 3, 5, and 10 years. The type and incidence of posttransplant complications were determined, as was the quality of long-term allograft function. The median follow-up period was 4.1 years. RESULTS: Biliary atresia was the most common cause (50.4%) of endstage liver disease in this patient population. The median recipient age was 2.4 years; 239 patients (54%) were younger than 3 years of age and 1 11 patients (25%) were younger than 1 year of age. There were 471 whole organs, 29 were ex vivo reduced size, 33 were living-related donor, and 36 were in situ split-liver allografts. Three hundred forty-three (78%) patients underwent a single allograft, whereas 97 patients required retransplantation; hepatic artery thrombosis was the most common indication for retransplantation (55 patients). The 1-, 3-, 5-, and 10-year actuarial patient survival rates were 82%, 80%, 78%, and 76%, respectively; allograft survival rates were 68%, 63%, 60%, and 54%. Long-term liver function remains excellent: current median follow-up values for total bilirubin and aspartate aminotransferase were 0.5 mg/dl and 54 IU/L, respectively. Cox multivariate regression analysis demonstrated that pretransplant patient age, the era of transplantation, and the number of allografts performed significantly and independently predicted patient survival rates, whereas allograft type and pretransplant diagnosis did not. CONCLUSIONS: Liver transplantation in the pediatric patient is a durable procedure that provides excellent long-term survival. Although there have been overall improvements in patient outcome with increased experience, the effect is most pronounced for patients younger than 1 year of age. Retransplantation, although effective in a meaningful number of patients, continues to carry a progressive decrement in survival with the number of allografts performed. Use of living-related and in situ split-liver allografts has dramatically reduced waiting times for small children and has improved patient survival.

Actuarial Analysis↗
PubMed1998

Functionally and phenotypically mature mouse CD8+ T cells develop in porcine thymus grafts in mice.

Mouse CD4+ T cells efficiently develop in fetal pig thymus (FP THY) grafts and repopulate the periphery of T cell and NK cell-depleted, thymectomized (ATX) mice. However, efficient peripheral repopulation of mouse CD8+ T cells does not occur in these mice. We have therefore evaluated the maturation and function of mouse CD8 single positive (SP) thymocytes in fetal pig thymus and liver fragment (FP THY LIV) grafts. Phenotypic maturity, as measured by upregulated expression of TCR, class I MHC, and Qa-2, and downregulated expression of heat stable antigen (HSA) on CD8 SP cells in FP THY grafts, was similar to that in host thymi of euthymic control mice. Cytolytic T lymphocyte (CTL) activity of thymocytes from FP THY grafts was similar to that of thymocytes from host thymi of euthymic mice, indicating that functional maturation of CD8 SP cells had taken place in the grafts. Furthermore, similarly efficient deletion of V beta 5.1/5.2+ and V beta 11+ CD8 SP cells was observed in FP THY grafts as in host thymi of euthymic control mice. Similar percentages of V beta 6, V beta 7, and V beta 8.1/8.2 expressing cells were also detected among CD8 SP cells in FP THY grafts and host thymi of euthymic controls. Together, our results suggest that normal positive and negative selection occurs, and that mouse CD8+ cells can undergo normal functional and phenotypic maturation in FP THY grafts. Thus, other explanations must be sought for the failure of CD8+ cells to repopulate the peripheral lymphoid tissues of ATX, T cell-depleted, pig THY/LIV-grafted mice.

Animals↗
PubMed1998

Separate regulation of peripheral hematopoietic and thymic engraftment.

Long-term multilineage chimerism, indicating pluripotent hematopoietic stem cell engraftment, was achieved in an Ly5-congenic strain combination without irradiation or other host conditioning when a large number of donor marrow cells (1.4-2x10(8)) was administered. However, the initial (2-4 weeks posttransplantation) percentages of T and B lymphocytes of donor origin were markedly lower than those of myeloid lineages. Steady-state levels of donor and host repopulation of all lineages were reached by 7 to 15 weeks posttransplantation and remained relatively constant for at least 41 weeks. B cell chimerism was similar to that seen in myeloid lineages at steady state. In contrast, long-term donor representation in the T cell lineage was much lower than in the B cell or myeloid lineages. Host treatment with depleting anti-T cell monoclonal antibodies increased the donor contribution to early T cell repopulation, but long-term T cell chimerism was still significantly lower in all lymphohematopoietic tissues, including the thymus, than B cell or myeloid cell chimerism. Pretreatment of hosts with 3.5 Gy of local irradiation to the thymic region further increased the donor contribution to initial T cell repopulation, which equaled that of other lineages at 4 to 7 weeks. However, donor representation in the T cell lineage declined by the time steady-state chimerism was attained and was lower than donor representation in the B cell or myeloid lineages. A higher dose of thymic irradiation (7 Gy) led to a reduction in this discrepancy, so that levels of donor thymopoiesis and hematopoiesis in other lineages were similar by 23 to 27 weeks posttransplantation. The differential contribution of adult donor marrow to long-term, steady-state thymopoiesis vs. hematopoiesis in other lineages under certain conditions in this competitive repopulation assay suggests that functionally distinguishable progenitors are responsible for these activities.

Animals↗
PubMed1997

Positive and negative selection of functional mouse CD4 cells by porcine MHC in pig thymus grafts.

Specific tolerance to discordant xenogeneic donors can be achieved by grafting of fetal pig thymic and liver tissue (FP THY/LIV) to T cell and NK cell-depleted, thymectomized (ATX) mice. Mouse CD4+ T cells develop in FP THY/LIV grafts, and demonstrate remarkably normal immune function, including host-restricted responses to keyhole limpet hemocyanin. We have therefore studied the role of host MHC class II in the development of mouse T cells in FP THY/LIV grafts by comparing their development in ATX MHC class II-deficient (IIKO) and wild-type (H-2b) mice. Mouse CD4+ T cells repopulated T/NK cell-depleted, ATX IIKO mice after grafting with FP THY/LIV, indicating that pig MHC can positively select mouse CD4 cells. Expression of TCR, MHC class I, Qa-2, heat-stable Ag, and CD45RB among double-positive and CD4 single-positive (SP) graft thymocytes in wild-type recipients was similar to that in normal mouse thymi, whereas CD4 SP thymocytes in grafts of IIKO mice showed increased Qa-2 and decreased heat-stable Ag expression, suggesting an increased level of maturity. Double-positive cells in grafts of IIKO mice also expressed higher than normal levels of Qa-2. Deletion within the grafts of Vbeta3+, Vbeta5.1/5.2+, and Vbeta11+ but not Vbeta6+, Vbeta7+, or Vbeta8.1/8.2+ mouse CD4 SP thymocytes in ATX IIKO mice demonstrated that swine leukocyte Ag participates in negative selection of the T cell repertoire. Therefore, porcine MHC mediates positive and negative selection of mouse thymocytes, but host class II MHC molecules also regulate thymocyte maturation in xenogeneic thymic grafts.

Animals↗
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↗
PubMed1997

Current and future treatment modalities for hepatocellular carcinoma.

This article reviews recent innovations in the treatment of Hepatocellular carcinoma (HCC), which, although a common malignancy, has often proved difficult to diagnose and treat effectively. The epidemiology and natural history of HCC are discussed, as well as treatments such as hepatic resection, liver transplantation, and cryosurgery, among others.

Antineoplastic Agents↗
PubMed1997

What's next for managed care? Panel discussion.

Change continues to be health care's only constant in the United States. As enrollment in managed care organizations skyrockets, the glare of public scrutiny intensifies. Success is no longer as simple as undercutting traditional fee-for-service providers; MCOs have to become more responsive to consumer needs as they compete with one another. Whether substantial set of values or mere buzzword, quality is the lingua franca of the MCO arena. Although MCO executives attribute the concept's ubiquity to many factors, the common denominator is staying competitive in a high-growth industry. Along with the elimination of the gatekeeper, a major trend to watch for is the rise of industry oversight provided by standardized practice guidelines. MCO executives recognized that implementing such measures will streamline operations and make MCOs more user-friendly.

Efficiency, Organizational↗
PubMed1997

The role of barium enema in colostomy closure in trauma patients.

Recently, the routine use of barium enema preceding colostomy closure in trauma patients has been challenged. It has been argued that the nature of the injury should be apparent from the initial laparotomy and that the likelihood of finding an unsuspected colonic lesion in the young, previously healthy patients who constitute the majority of trauma patients is very small. We retrospectively reviewed 124 consecutive cases of patients who received colostomy takedowns for trauma. One hundred six of the patients had preoperative barium enema evaluation. 87.1 per cent of the examinations were negative, with a subsequent stoma closure complication rate of 20.4 per cent. Of the 13 positive barium enemas, 9 were falsely positive. These patients had a higher stoma closure complication rate of 39 per cent, a fact that could not be explained on the basis of their abnormal studies. The 18 patients who did not have barium enema performed did not have an increase in complications (17.6%). Barium enema failed to uncover unsuspected pertinent diagnoses, often added unnecessary delays and expense, and in no case changed the operative management. Contrast studies were found to be useful in defining anatomy in cases of known fistulas and when the takedowns were performed without the benefit of operative reports from the previous surgery.

Adolescent↗
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↗