Biomedical subjects

C K Breuer

Publications and source records attributed to C K Breuer.

10 recordsLinked to original sources

PubMed2000

The unpredictable character of congenital cystic lung lesions.

BACKGROUND: The spectrum of congenital cystic disease of the lung ranges from hydrops and neonatal respiratory distress to asymptomatic lesions. Surgical management is dictated by the presence of symptoms, recurrent infection, and the potential risk of malignant transformation. METHODS: Since 1995, all consecutive patients with congenital cystic lung lesions underwent follow-up for symptoms, treatment, and correlation of presumptive with pathological diagnosis. RESULTS: Twelve cystic lung lesions were identified. Seven were diagnosed with mediastinal shift in utero; in 6 of 7, the shift subsequently resolved. Overall, 6 of 7 lesions that were followed up serially decreased in size. Two patients were symptomatic in utero; 1 underwent thoracoamniotic shunting, 1 pleurocentesis for impending hydrops. Postnatally, these 2, and 2 other newborns required urgent surgery. Five of 8 asymptomatic patients had elective resection by 16 months, and 4 await operation. In 6 of the 9 surgical cases (67%), there was a discrepancy between preoperative and pathological diagnosis. There were 4 hybrid congenital cystic adenomatoid malformation (CCAM)/sequestrations. CONCLUSIONS: At least 6 of 7 congenital cystic lung lesions decreased in size regardless of gestational age or presence of mediastinal shift. Antenatal intervention is therefore rarely indicated. Hybrid morphology may necessitate resection of stable, asymptomatic lesions to prevent the theoretical concern for associated malignancies as well as other complications of CCAM.

Adult↗

PubMed1999

Cost-effectiveness of laparoscopy in children.

BACKGROUND: Laparoscopy may offer fast recovery and improved cosmesis, but its cost has been perceived as excessive. OBJECTIVE: To analyze the total hospital costs of laparoscopy vs open surgery. DESIGN: Retrospective cost-effectiveness analysis evaluating all cases performed in a 36-month period (September 1995 to August 1998). Cases were evaluated for operative time, itemized cost of supplies, and length of hospitalization. SETTING: Operations performed by pediatric surgeons in a tertiary care children's hospital. PATIENTS: Consecutive children undergoing laparoscopic or open appendectomies, cholecystectomies, fundoplications, and splenectomies. Patients were not randomized to laparoscopy, or open surgery. INTERVENTIONS: Laparoscopic procedures performed with a core set of reusable equipment and a limited number of disposable instruments. MAIN OUTCOME MEASURES: Cost surplus of laparoscopy was evaluated, and compared with savings associated with decreased hospital stay, to obtain cost-effectiveness of laparoscopy per procedure. RESULTS: There were 26 laparoscopic and 359 open appendectomies; 33 laparoscopic and 3 open cholecystectomies; 16 laparoscopic and 18 open fundoplications; and 16 laparoscopic and 7 open splenectomies. Excess operating costs per procedure were $442.00 for appendectomy, $634.60 for fundoplication, $847.50 for cholecystectomy, and $1551.30 for splenectomy. Hospital stay was decreased for all laparoscopies, resulting in an overall savings per laparoscopic procedure of $2369.90 for appendectomy, $5390.90 for fundoplication, $1161.00 for cholecystectomy, and $858.90 for splenectomy. CONCLUSIONS: Laparoscopy is cost-effective, particularly for fundoplication, appendectomy, and cholecystectomy. Detailing the costs of supplies, operating time, and length of stay allows interinstitutional comparison and critical cost-analysis of laparoscopy. With a more selective use of reusable instruments and further shortening of operative time, the global savings of laparoscopy may increase.

Adolescent↗

PubMed1999

Surgical management of necrotizing Candida esophagitis.

Invasive esophageal candidiasis produced transmural necrosis leading to perforation in 2 patients aged 10 and 27 years. Both patients survived after esophageal resection and complete diversion. One patient with acute leukemia and neutropenia experienced systemic candidiasis, which resolved after esophagectomy. Esophagectomy and diversion for yeast-induced necrosis may lead to complete recovery and resolution of disseminated candidiasis when combined with systemic antifungal therapy.

Adult↗

PubMed1999

Incidence of contralateral inguinal hernia: a prospective analysis.

BACKGROUND/PURPOSE: Contralateral groin exploration in children with unilateral inguinal hernia is still controversial, particularly in infants. The authors have attempted to determine the age- and gender-stratified incidence of contralateral hernia and the necessity of routine bilateral procedures. METHODS: This is a prospective study of 656 patients during a 34-month period at a single institution. Patients with unilateral hernia underwent an ipsilateral procedure only, regardless of age, gestational age, or gender. Follow-up was 6 to 40 months (mean, 25.5 months). Chi-square analysis was used for intergroup comparison (P < .05 significant). RESULTS: Of 656 children, 108 (16.5%) presented with synchronous bilateral hernias. Bilateral inguinal hernia was significantly more common in premature infants (28.0%) and young children (33.8% if <6 months, 27.4% if <2 years). Of the remaining 548, a metachronous contralateral hernia developed in 48 (8.8%) at a median interval of 6 months (range, 4 days to 7 years). This incidence was 13 of 105 (12.4%) in infants less than 6 months of age, 20 of 189 (10.6%) in children less than 2 years of age, 8 of 54 (14.8%) in premature infants, 6 of 81 (7.4%) in girls, and 8 of 29 (27.6%) in children with an incarcerated hernia. In the latter group, P < .05, chi2 analysis. CONCLUSION: Routine contralateral inguinal exploration, without clinical evidence of a hernia, may be advisable in children with incarceration and possibly in premature infants. The low incidence of contralateral hernias in all other patients, regardless of gender or age, does not justify routine contralateral exploration.

Adolescent↗

PubMed1999

Evaluation of methods of hepatotrophic stimulation in rat heterotopic hepatocyte transplantation using polymers.

BACKGROUND: Hepatocyte transplantation has been studied as an alternative to organ transplantation. Hepatocyte transplant models should provide sufficient cell mass for replacement function and hepatotrophic stimulation of the transplanted cells in heterotopic locations. METHOD: The authors used three-dimensional porous polyvinyl-alcohol matrices as cell carriers, which were implanted between mesenteric leaves of the intestine. In this study, different methods were evaluated for hepatotrophic stimulation. Fifty million transplanted hepatocytes (approximately 10% liver mass) were implanted in Lewis rats. We compared 70% partial hepatectomy, portacaval shunt, cotransplantation of enterocytes, cotransplantation of islets of Langerhans, and methylprednisolone injection to a control group with only hepatocyte transplantation. Portacaval shunt and islet cotransplantation also were used in combination. Specimens were harvested 2 weeks after transplantation, and area per histological cross section compromised by hepatocytes was measured. RESULTS: Seventy percent partial hepatectomy, enterocyte cotransplantation, and methylprednisolone injection resulted in hepatocyte maintenance similar to control group (3,100 +/- 7,592 microm2). Portacaval shunt (96,866 +/- 55,039 microm2) and islet cotransplantation (173,020 +/- 75,977 microm2) yielded a highly significant increase in hepatocyte area. The combination of portacaval shunt and islet cotransplantation resulted in a significant increase compared with using these methods individually (288,930 +/- 86,726 microm2). Additional immunohistochemical stains for active DNA synthesis, insulin, and glucagon demonstrated the proliferative abilities of the hepatocytes and the synthesis of insulin and glucagon in the cotransplanted islets. CONCLUSION: Hepatocyte transplantation can be performed using polymer carriers and that hepatocyte survival and maintenance can be improved with portacaval shunt and islet cotransplantation.

Animals↗

PubMed1997

The in vitro construction of a tissue engineered bioprosthetic heart valve.

PROBLEM: Heart valve replacement with either a nonliving xenograft or a mechanical prosthesis is an effective therapy for valvular heart disease. Both of these approaches have limitations, including their inability to grow, repair, and remodel. In addition, a mechanical prosthesis requires long-term anticoagulation therapy. METHODS: This study demonstrates the in vitro creation of tissue engineered heart valve tissue using cardiovascular cells on degradable polymer matrices, 40 heart valve leaflets were created using this technique from two sources. Xenograft leaflets were created using human dermal fibroblasts and bovine aortic endothelial cells (n = 20) or allograft valve leaflets were created using sheep myofibroblasts and sheep endothelial cells (n = 20). A mixed sheep cell population was obtained consisting of endothelial cells and myofibroblasts. Endothelial cells were labelled with acethylated low density lipoprotein (Ac-Dil-LDL) and cells were separated into two groups using an activated cell sorter: LDL positive cells comprised of a pure endothelial cell population and LDL negative cells comprised of mixed cell population containing myofibroblasts and smooth muscle cells. The LDL negative cells were seeded on a synthetic polyglycolic acid (PGA) mesh and grown in vitro to form a tissue-like fibroblast-mesh core. Endothelial cells were then seeded onto the surface of the fibroblast-mesh core, forming a single monolayer. RESULTS: Histological evaluation of these constructs revealed an inner core of LDL negative cells and outer endothelial-like cells which were factor VIII positive. There was no evidence of capillary formation from endothelial cells invading the myofibroblasts and smooth muscle matrix and the endothelial lining appeared complete. CONCLUSIONS: It is feasible to construct allogenic heart valve tissue which could be used to make a valve.

Animals↗

PubMed1996

Tissue-engineered heart valves. Autologous valve leaflet replacement study in a lamb model.

BACKGROUND: We have previously reported the successful creation of tissue-engineered valve leaflets and the implantation of these autologous tissue leaflets in the pulmonary valve position. This study was designed to trace cultured cells that were seeded onto a biodegradable polymer with the use of a 1,1'-dioctadecyl-3,3,3' 3'-tetramethylindo-carbocyanine perchlorate (Di-1) cell-labeling method. We also examined the time-related biochemical, biomechanical, and histological characteristics and evolution of these tissue constructs. METHODS AND RESULTS: Mixed cell populations of endothelial cells and fibroblasts were isolated from explanted ovine arteries. Endothelial cells were selectively labeled with an acetylated low density lipoprotein marker and separated from fibroblasts with the use of a fluorescence-activated cell sorter. A synthetic biodegradable scaffold consisting of polyglycolic acid fibers was seeded first with fibroblasts, then coated with endothelial cells. Using these methods, we implanted autologous cell/polymer constructs in six animals. In two additional control animals, a leaflet of polymer was implanted without prior cell seeding. In each animal, cardiopulmonary bypass was used to completely resect the right posterior leaflet of the pulmonary valve and replace it with an engineered valve leaflet with (n = 6) or without (n = 2) prior cultured cell seeding. The animals were killed either after 6 hours or after 1, 6, 7, 9, or 11 weeks, and the implanted valve leaflets were examined histologically, biochemically, and biomechanically. 4-Hydroxyproline assays were performed to determine collagen content. Leaflet strength was evaluated in vitro with a mechanical tester Factor VIII and elastin stains were done to verify histologically that endothelial cells and elastin, respectively, were present. Animals receiving leaflets made from polymers without cell seeding were killed and examined in a similar fashion after 8 weeks. In the control animals, the acellular polymer leaflets were completely degraded, with no residual leaflet tissue at 8 weeks. The tissue-engineered valve leaflet persisted in each animal in the experimental group. 4-Hydroxyproline analysis of the constructs showed a progressive increase in collagen content. Immunohistochemical staining demonstrated elastin fibers in the matrix and factor VIII on the surface of the leaflet. The cell-labeling experiments demonstrated that the cells on the leaflets had persisted from the in vitro seeding of the leaflets. CONCLUSIONS: In the tissue-engineered heart valve leaflet, transplanted autologous cells generated a proper matrix on the polymer scaffold in a physiological environment at a period of 8 weeks after implantation.

Animals↗

PubMed1996

Effects of nitric oxide on hyperinflation-induced pulmonary hypertension in the isolated-perfused lung.

OBJECTIVE: To determine if nitric oxide decreases pulmonary vascular resistance in hyperinflation-induced pulmonary hypertension. DESIGN: Isolated-perfused lamb lung model. SETTING: Experimental animal laboratory in a university setting. SUBJECTS: Ten isolated-perfused lamb lungs harvested from subjects with a mean age of 29 days. INTERVENTIONS: After induction of anesthesia, endotracheal intubation, and mechanical ventilation, lungs were perfused via an extracorporeal circuit. Ventilatory pressures were set to provide tidal volumes of 10 mL/kg and ventilatory rates were adjusted to maintain a Paco2 of 40 +/- 5 torr (3.5 +/- 0.7 kPa). The perfusion system consisted of a blood reservoir, a membrane oxygenator, and a nonocclusive roller pump. Blood flow was increased progressively to 50 mL/kg/min, maintaining a pulmonary arterial pressure of < 25 mm Hg and a left atrial pressure between 2 and 5 mm Hg. End-expiratory lung volume was measured using a nitrogen washout method. Baseline data were collected after a 1-hr stabilization period. Lung volume was increased to achieve 25% (moderate hyperinflation) and 50% (severe hyperinflation) increments in pulmonary vascular resistance. Nitric oxide (80 parts per million) was administered to the preparation after each increment in lung volume. MEASUREMENTS AND MAIN RESULTS: Mean pulmonary arterial pressure, mean left atrial pressure, pulmonary vascular resistance, and static lung compliance were measured at baseline and after moderate and severe hyperinflation, both before and after nitric oxide administration. Significant decreases in pulmonary vascular resistance were found when the preparation was ventilated with nitric oxide at baseline (43% decrease) and during hyperinflation induced pulmonary hypertension at both moderate (31% decrease) and severe (23% decrease) levels of hyperinflation. CONCLUSIONS: Inhaled nitric oxide significantly reduces pulmonary vascular resistance, even when pulmonary hypertension is induced by airway hyperinflation and supraphysiologic lung volumes. These data suggest that the use of nitric oxide following lung transplantation may allow for effective management of pulmonary hypertension in patients who receive allografts from undersized donors. Further clinical experience will be crucial in precisely defining the range of donor-recipient size mismatch that can be adequately managed and the time course over which nitric oxide can be administered safely and effectively to these patients.

Animals↗

PubMed1995

Tissue engineering heart valves: valve leaflet replacement study in a lamb model.

BACKGROUND: Valve replacements using either bioprosthetic or mechanical valves have the disadvantage that these structures are unable to grow, repair, or remodel and are both thrombogenic and susceptible to infection. These characteristics have significantly limited their durability and longevity. In an attempt to begin to overcome these shortcomings, we have tested the feasibility of constructing heart valve leaflets in lambs by seeding a synthetic polyglycolic acid fiber matrix in vitro with fibroblasts and endothelial cells. METHODS: Mixed cell populations of endothelial cells and fibroblasts were isolated from explanted ovine arteries. Endothelial cells were selectively labeled with an acetylated low-density lipoprotein marker and separated from the fibroblasts using a fluorescent activated cell sorter. A synthetic biodegradable scaffold constructed from polyglycolic acid fibers was seeded with fibroblasts, which grew to form a tissue-like sheet. This tissue was subsequently seeded with endothelial cells, which formed a cellular monolayer coating around the leaflet. Using these constructs, autologous (n = 3) and allogenic (n = 4) tissue engineered leaflets were implanted in 7 animals. In each animal the right posterior leaflet of the pulmonary valve was resected and replaced with an engineered valve leaflet. RESULTS: All animals survived the procedure. Postoperative echocardiography demonstrated no evidence of stenosis and trivial pulmonary regurgitation in the autografts and moderate regurgitation in the allogenic valves. Collagen analysis of the constructs showed development of an extracellular matrix. Histologic evaluation of the constructs demonstrated appropriate cellular architecture. CONCLUSIONS: This preliminary experiment showed that a tissue engineered valve leaflet constructed from its cellular components can function in the pulmonary valve position. Tissue engineering of a heart valve leaflet is feasible, and these preliminary studies suggest that autograft tissue will probably be superior to allogenic tissue.

Animals↗

PubMed1994

The importance of staging laparotomy in pediatric Hodgkin's disease.

The findings of 247 pediatric patients who presented with supradiaphragmatic Hodgkin's disease and underwent staging laparotomies between April 1969 and December 1991 were reviewed to assess the importance of the staging laparotomy in pediatric Hodgkin's disease. A change in stage occurred in 25% of the cases reviewed. Fifty of the 202 (25%) clinical stage (CS) I or II patients were upstaged to pathological stage (PS) III or IV, and 12 of the 45 (27%) clinical stage III or IV patients were downstaged to pathological stage I or II. Possible risk factors for positive surgical staging, including gender, age, presence or absence of B symptoms, extent of involvement above the diaphragm, and histological type, were used to define subgroups of patients. Three statistically significant subgroups of patients with less than a 10% chance of restaging were identified. These groups included CS I and II patients with lymphocyte-predominant histology, CS I females, and CS III and IV females with nonlymphocyte predominant histology. These subgroups represent 24% of the cohort. Because CS is an accurate predictor of PS in these groups, treatment could be based solely on CS. The impact of radiographic imaging techniques on correctly predicting pathological stage was assessed. The rates of restaging for individuals with lymphangiography or computed axial tomography were not statistically different from those of patients without these radiographic studies. Therefore, abdominal imaging is not a substitute for surgical staging. No mortality and 2.8% morbidity occurred from staging laparotomy. Postsplenectomy sepsis and small bowel obstruction were the most common complications. Ninety-six percent of upstaged patients had splenic involvement, and 54% had positive nodal involvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗