PubMed Health⌕ Search

Biomedical subjects

J C Dunn

Publications and source records attributed to J C Dunn.

At least 19 recordsLinked to original sources
PubMed2001

The utility of lung biopsy in recipients of stem cell transplantation.

BACKGROUND/PURPOSE: Pulmonary infiltrates in recipients of stem cell transplantation often present as diagnostic dilemmas. Although lung biopsy may establish the diagnosis of parenchymal disease, it remains unclear whether such a procedure results in a significant change in the patient's treatment and outcome. This study evaluates the efficacy of lung biopsy in recipients of stem cell transplantation. METHODS: The medical records of 15 stem cell transplant recipients who underwent 18 lung biopsies were reviewed. The indications for stem cell transplantation were leukemia in 10 patients, lymphoma in 2, histiocytosis in 1, neuroblastoma in 1, and Ewing's sarcoma in 1. The results of the lung biopsies were correlated to the clinical management and outcomes. RESULTS: The overall mortality rate was 67% (10 patients). Eight of the 9 patients who required mechanical ventilatory support at the time of lung biopsy died. The pathologic diagnoses were pneumonitis in 6 biopsies, fibrosis in 6, brochiolitis obliterans organizing pneumonia in 3, hemorrhage in 2, and infarction in 1. Therapy was changed in 1 patient who improved after a course of steroids for bronchiolitis obliterans organizing pneumonia. Lung biopsy cultures were positive in 6 patients but rarely resulted in changes in antibiotic therapy. CONCLUSIONS: Results of very few lung biopsies performed in stem cell transplant recipients redirected therapy. Furthermore, the ultimate outcome of these patients were not improved by the results of lung biopsies.

Adolescent↗
PubMed2000

Model complexity: the fit to random data reconsidered.

A recent controversy in the field of depth perception has highlighted an important aspect of model testing concerning a model's complexity, defined as the prior propensity of the model to fit arbitrary data sets. The present article introduces an index of complexity, called the mean minimum distance, defined as the average squared distance between an arbitrary data point and the prediction range of the model. It may also be expressed as a dimensionless quantity called the scaled mean minimum distance. For linear models, theoretical values for the scaled mean minimum distance and the variance of the scaled minimum distance can be readily obtained and compared against empirical estimates obtained from fits to random data. The approach is applied to resolving the question of the relative complexity of the Linear Integration model and the Fuzzy Logic of Perception model, both of which have been the subject of controversy in the field of depth perception. It is concluded that the two models are equally complex.

Humans↗
PubMed2000

Functional and morphologic changes of the ileal mucosa after ileoanal pouch procedure.

BACKGROUND: Restorative proctocolectomy is used widely for treatment of ulcerative colitis and familial polyposis coli. Limited information is available regarding the morphologic and functional adaptation of the mucosa in a functioning ileoanal pouch. STUDY DESIGN: Ileal pouch specimens from patients who underwent pouch reconstruction (mean 7.5 years postcolectomy, n = 12) were compared with normal ileum (n = 15) and normal colon (n = 5). Amino-oligopeptidase (AOP) and maltase activity were measured as parameters of normal ileal function. Histologic samples were examined for the presence of neutrophils and plasma cells, the villus to crypt height ratio, and the degree of crypt hyperplasia, villus blunting, and goblet cell mass. Data were analyzed by analysis of variance. RESULTS: The AOP activity in the normal ileum was 73 +/- 32 units of enzymatic activity per gram of mucosal protein; the AOP activities of the pouch and colon were 21 +/- 22 and 16 +/- 10, respectively. The maltase activity of the normal ileum measured 254 +/- 116 units of enzymatic activity per gram of mucosal protein, and the maltase activities of the pouch and colon were 57 +/- 71 units and 29 +/- 25 units, respectively. The ileal pouch mucosa demonstrated little acute inflammation and varying degrees of chronic inflammation. Morphologically, the ileal pouch mucosa demonstrated a range of adaptations, including villus blunting and crypt hyperplasia. Several specimens contained immature epithelial cells. CONCLUSIONS: The AOP and maltase activities in mucosa from ileoanal pouches and colon were significantly lower than those in normal ileal mucosa. Ileoanal pouch mucosa from humans undergoes adaptive changes to resemble colonic mucosa both morphologically and functionally.

Adult↗
PubMed2000

Repair of pectus excavatum deformities: 30 years of experience with 375 patients.

OBJECTIVE: To review the surgical experience with pectus excavatum chest deformities at UCLA Medical Center during a 30-year period. BACKGROUND: Pectus excavatum is a relatively common malformation that is often symptomatic; however, children's physicians often do not refer patients for surgical correction. METHODS: Hospital records from 375 patients who underwent repair of pectus excavatum deformities between 1969 and 1999 were reviewed. Decrease in stamina and endurance during exercise was reported by 67%; 32% had frequent respiratory infections, 8% had chest pain, and 7% had asthma. The mean pectus severity score (width of chest divided by distance between posterior surface of sternum and anterior surface of spine) was 4.65 (normal chest = 2.56). All patients had marked cardiac deviation into the left chest. Repair was performed with subperiosteal resection of the abnormal cartilages, transverse wedge osteotomy of the anterior sternum, and internal support with a steel strut for 6 months. Repair was performed on 177 children before age 11 years; 38 adults with severe symptoms underwent repair. RESULTS: The mean hospital stay was 3.1 days. With a mean follow-up of 12.6 years, all patients with preoperative respiratory symptoms, exercise limitation, and chest pain experienced improvement. Vital capacity increased 11% (mean) within 9 months in 35 patients evaluated. There were no deaths. Complications included hypertrophic scar formation (35), atelectasis (12), pleural effusion (13), recurrent sternal depression (5), and pericarditis (3). More than 97% had a very good or excellent result. CONCLUSION: Pectus excavatum deformities can be repaired with a low rate of complications, a short hospital stay, and excellent long-term physiologic and cosmetic results.

Adolescent↗
PubMed2000

The spectrum of mucin-producing adenocarcinoma of the pancreas.

The clinical distinction between cystic and mucinous carcinomas of the pancreas has been poorly defined. Therefore we sought to stratify the entity known as pancreatic mucinous adenocarcinoma based on pathologic and clinical criteria. Clinical data and pathology specimens were reviewed for patients (n = 40) who had been diagnosed as having mucin-producing pancreatic adenocarcinoma and had undergone either resection or intraoperative biopsy of their pancreatic tumor during a 40-year period at the UCLA Medical Center. Based on histologic criteria, three distinct classes of pancreatic adenocarcinoma were identified: mucinous noncystic (colloid) adenocarcinoma (group I), mucinous cystadenocarcinoma (group II), and ductal adenocarcinoma (group III). Based on clinical behavior, groups I and III were indistinguishable. Compared to patients from groups I and III, those from group II were younger, more likely to be female, and had a better prognosis. Among mucin-producing adenocarcinomas of the pancreas, mucinous noncystic adenocarcinoma and ductal adenocarcinoma share similar clinical features, whereas true cystic lesions represent a distinct clinical entity.

Adenocarcinoma, Mucinous↗
PubMed1999

The influence of gestational age and mode of delivery on infants with gastroschisis.

BACKGROUND/PURPOSE: It has been proposed that preterm and prelabor cesarean section may improve the outcome of infants with gastroschisis. The purpose of this study is to examine the impact of gestation and delivery method on infants with gastroschisis. METHODS: The medical records of 60 infants with gastroschisis treated at a tertiary care center from 1985 through 1995 were reviewed retrospectively. The gestational age, the mode of delivery, the type of operative repair, and the length of hospital stay were recorded for each patient. RESULTS: Infants born vaginally were more likely to require silo stage repair than those delivered by cesarean section (21 of 29 v. 11 of 31, P<.01). Infants born vaginally also had longer hospital stay than those delivered by cesarean section (53 v. 39 days, P = .19). Infants born before 33 weeks' of gestation stayed longer in the hospital than those born after 33 weeks. After 33 weeks' gestation, infants had similar hospital stay regardless of the gestational age. CONCLUSIONS: Cesarean section delivery was beneficial for infants with gastroschisis. Preterm delivery did not shorten the length of hospital stay. The role of elective cesarean section delivery at term should be considered for infants with gastroschisis diagnosed antenatally.

Cesarean Section↗
PubMed1999

Reoperation after esophageal replacement in childhood.

BACKGROUND: Esophageal replacement is associated with significant morbidity that may lead to operative interventions. This study reviews the management and outcome of children who underwent reoperation after esophageal replacement. METHODS: Eighteen patients who underwent esophageal replacement from 1985 to 1997 were reviewed retrospectively. Ten patients underwent reoperation. Patient management, perioperative morbidity, and the dietary intake at follow-up were recorded for each patient. RESULTS: Of the reoperated patients, 7 had esophageal atresia, 2 had caustic ingestion, and 1 had achalasia. Nine patients received a colon interposition, and 1 received a reverse gastric tube as the initial esophageal replacement. Seven patients required revision of the anastomoses. Three patients required complex esophageal reconstruction: 1 underwent gastric transposition, 1 underwent free jejunal graft, and 1 underwent gastric transposition combined with free jejunal graft. Seven patients were eating well at follow-up. Two patients still required partial gastrostomy tube feeding. One patient died 6 months postoperatively from aspiration pneumonia. CONCLUSIONS: Esophageal replacement continues to be a challenging operation associated with significant complications. Most reoperative procedures were directed toward strictures and persistent fistulae. Complete graft failure can be managed by gastric transposition or free jejunal graft. Despite the perioperative morbidity, most patients have good functional outcome.

Adolescent↗
PubMed1999

Simplifying the Waterston's stratification of infants with tracheoesophageal fistula.

The survival of infants with tracheoesophageal fistula was stratified by David J. Waterston et al. in 1962. This classification has been used as a guide to direct the timing of operative intervention in these infants. This study examines the current applicability of this classification system. The hospital records of 64 infants with esophageal atresia and/or tracheoesophageal fistula were reviewed. The survival rate was analyzed as a function of the infants' risk stratification, birth weight, and additional anomalies. Twenty-three infants were in Waterston Group A, 20 infants in Group B, and 21 infants in Group C. The survival of all infants was 81 per cent. Six infants died after recognition of severe anomalies and withdrawal of care, four infants died of cardiopulmonary arrest, and two infants died of sepsis. The survival of infants in both Groups A and B was 100 per cent, in contrast to 43 per cent survival in Group C. Only infants who weighed <1800 g or had severe additional anomalies were at risk of dying. Therefore, the classification of infants with esophageal atresia and/or tracheoesophageal fistula may be simplified by combining Waterston's Groups A and B into a single risk stratum.

Esophageal Atresia↗
PubMed1998

Long-term quantitative results following fundoplication and antroplasty for gastroesophageal reflux and delayed gastric emptying in children.

BACKGROUND: The operative management of children with combined gastroesophageal reflux and delayed gastric emptying is controversial. This study measures the long-term follow-up of gastric emptying in children who have undergone gastroesophageal fundoplication combined with antroplasty. METHODS: Fifteen randomly selected children with gastroesophageal reflux and scintigraphically demonstrated delayed gastric emptying underwent fundoplication and antroplasty. Each patient had another gastric emptying scintigraphic study performed an average of 3.6 years postoperation. RESULTS: All patients reported improvement of their symptoms compared with before the operation, and none required further medical therapy for gastroesophageal reflux or experienced dumping syndrome. Eleven of the 15 patients had significant long-term improvement of their gastric emptying postoperatively. The mean percent of isotope meal remaining in the stomach at 90 minutes improved from 72% preoperatively to 40% postoperatively (P = 0.0005). CONCLUSIONS: Gastric emptying in children with gastroesophageal reflux and delayed gastric emptying is significantly improved for several years in three-fourths of patients after fundoplication and antroplasty. Fundoplication and concomitant antroplasty are recommended for symptomatic children with documented gastroesophageal reflux and delayed gastric emptying.

Adolescent↗
PubMed1998

In vivo growth of transplanted genetically altered intestinal stem cells.

PURPOSE: Intestinal stem cell transplantation is a potential method of delivering genes to the small intestine. The authors have previously demonstrated the survival of transfected intestinal stem cells implanted into the rat small intestine. This study examines the growth of genetically altered intestinal stem cells that were grown on a polycarbonate membrane and implanted into the rat small intestine. METHODS: The IEC6 rat intestinal cell line serves as a model for intestinal stem cells. A subclone of the IEC6 cells was developed that stably expresses the lac Z gene introduced by a retroviral vector. The transfected cells were seeded at 500,000 cells/cm2 on a polycarbonate membrane. In 15 male Sprague-Dawley rats, a 0.75-cm enterotomy was created on the antimesenteric side of the small intestine 5 cm distal to the ligament of Treitz. A 0.5-cm2 segment of the membrane was sutured over the enterotomy with the cells facing away from the intestinal lumen. A segment of the omentum was wrapped around the patched enterotomy and sutured to the serosa. Three and 7 days after implantation, the implanted cells were retrieved, then fixed and stained with an X-gal solution. The number of cells was determined from the intensity of the X-gal staining. In five of the rats, frozen sections of the enterotomy sites were examined after staining with X-gal. RESULTS: All 15 rats survived the implantation procedure. Initially, 0.32 +/- 0.11 million cells were implanted. At both 3 and 7 days, the enterotomy site still contained viable transfected cells. The number of viable cells increased substantially to 1.52 +/- 0.46 and 3.52 +/- 1.87 million cells at 3 and seven days, respectively (P < .05). CONCLUSIONS: The polycarbonate membrane served as a good vehicle to efficiently deliver genetically altered intestinal stem cells to the small intestine. The transplanted cells continued to grow and stably expressed the gene product. This ex vivo approach to gene therapy has considerable therapeutic potential.

Animals↗
PubMed1998

The outcome of research training during surgical residency.

BACKGROUND/PURPOSE: The exposure to research during residency is currently an integral part of most academic surgical training programs. In this study, graduates of two surgical programs were surveyed to characterize their research experience and to determine the effects on their careers. METHODS: Between 1975 and 1990, 86 and 61 residents completed general surgical training programs at UCLA Medical Center and at Harbor-UCLA Medical Center, respectively. An anonymous survey was sent to each graduate regarding his research experience and current practice. RESULTS: Of the graduates who spent 2 years in research, 47% now hold academic positions, compared with 23% for those who spent less than 2 years (P = .18). When the graduates were segregated according to their desire to enter the laboratory, 49% of graduates who requested research time hold academic positions, whereas only 13% of those who would not request research are in academic positions (P = .01). CONCLUSIONS: Residents who strongly desire a period of research during surgical residency are also more productive in the laboratory. This information should be considered in selecting residents for research training in the current era of academic budget restriction and managed health care.

Attitude of Health Personnel↗
PubMed1998

Glucose uptake in dilated small intestine.

BACKGROUND/PURPOSE: The development of dilated small intestine in patients with short bowel syndrome results in increased mucosal surface area. This study examines whether the incremental increase in surface area leads to a proportional increase in absorptive function of the small intestine. METHODS: Partial obstruction of the small intestine was created in rats by placing an intussusception valve in the proximal jejunum. Rats that underwent sham operations served as controls. One week postoperatively, the small intestine proximal and distal to the valve was removed. The intestinal diameter proximal and distal to the obstruction was measured. The rate of glucose uptake was measured by the everted sleeve technique. The results were analyzed by analysis of variance (ANOVA). RESULTS: The intestine proximal to the valve was significantly dilated and thickened when compared with the intestine distal to the valve. The wet mass per centimeter of the dilated segment was 2.5 times that of the control group (P<.001). The glucose uptake capacity of the dilated segment was slightly higher than that of the control group (540 v 420 nmol/min/cm, P<.05). However, the specific glucose uptake rate was reduced significantly in the intestine proximal to the valve (247 v 335 nmol/min/cm2, P<.01). CONCLUSIONS: Although the partial obstruction of small intestine resulted in a substantial increase in the intestinal surface area, the absorptive capacity of the dilated intestine per unit surface area was decreased significantly. This translated ultimately into a slight increase in the overall functional absorptive capacity of glucose in the small intestine. These results suggest that dilated small intestine may not enhance mucosal absorption.

Analysis of Variance↗
PubMed1997

Epidermal growth factor selectively enhances functional enterocyte adaptation after massive small bowel resection.

After massive small bowel resection, the intestine adapts to compensate. In addition to proliferation, enterocytes also undergo selective functional adaptation. In this study we examined the effect of intraperitoneal administration of epidermal growth factor (EGF) on the expression of the brush border dissacharidase sucrase, the sodium glucose cotransporter (SGLT1), and the sodium-potassium ATPase pump (NaK ATPase) by enterocytes in the remnant intestine after massive small bowel resection. Adult Lewis rats underwent either ileal transection or 70% proximal intestinal resection. These animals were subdivided into groups that received either saline or EGF intraperitoneally for 1 week. Ilea from each group were harvested 4 weeks postoperatively. Enterocytes were separated from these segments by calcium chelation. The total protein from the isolated cells was subjected to Western blot analysis. Administration of EGF to animals that underwent transection did not significantly alter the expression of sucrase, SGLT1, or NaK ATPase. After intestinal resection, the expressions of sucrase and SGLT1 were significantly increased. The combination of EGF administration and intestinal resection resulted in a further increase in SGLT1 expression. The intraperitoneal administration of EGF selectively enhanced the expression of SGLT1 by enterocytes after massive small bowel resection. Administration of EGF to sham-operated animals did not have similar effects. These results suggest that EGF augments the adaptive response and may therefore have a therapeutic role in the management of patients with short bowel syndrome.

Adaptation, Physiological↗
PubMed1997

Improved survival of infants with omphalocele.

BACKGROUND: The surgical management of patients with omphalocele has evolved over the past 4 decades. Despite many improvements in care, the reported mortality has been over 10%. METHODS: This study reviewed the characteristics, management, and outcome of 31 patients with omphalocele who underwent surgical care between 1980 and 1995 at a single hospital. RESULTS: Twenty-five patients had additional congenital anomalies. All but 1 patient underwent operative repair; 13 of these patients with large defects had a silo chimney constructed initially. Fourteen patients underwent primary fascial and skin closure at the initial operation. Only 1 patient died perioperatively; another patient died without operation due to other major malformations. CONCLUSIONS: The results following surgical repair of omphalocele defects depend on the degree of visceroabdominal disproportion and on the severity of associated anomalies. The operative mortality for staged omphalocele repair with limited elevation of intraabdominal pressure is low, and the long-term quality of life of these patients is good.

Female↗
PubMed1996

Amiloride inhibits meal-stimulated colonic absorption.

Meal-stimulated colonic absorption has recently been described, but the cellular transport mechanisms mediating this response are unknown. The purpose of this study was to determine the contribution of Na+ transport pathways to colonic proabsorption. Distal colonic Thiry-Vella loops were constructed in six dogs. Absorption was measured by infusing the loops with a physiological electrolyte solution containing [14C] polyethylene glycol as the impermeant marker. In the first set of experiments, the dose dependence of amiloride-induced inhibition of basal colonic absorption was determined. In the second set of experiments the effect of amiloride, which inhibits both Na+ channels and Na+/H+ exchange in colonocytes, on meal-stimulated colonic absorption was determined. Luminal amiloride inhibited basal colonic absorption in a dose-dependent manner, with significant reductions in Na+ absorption occurring with concentrations of 10(-2)M and higher. Infusion with 10(-3)M amiloride, a concentration that did not alter basal absorption, resulted in significant reductions in postprandial water, Na+, and Cl- absorption. These results suggest that meal-stimulated colonic absorption is mediated, at last in part, by transcellular Na+ absorptive pathways.

Amiloride↗
PubMed1996

Enterocyte functional adaptation following intestinal resection.

Following massive small bowel resection, the remaining intestine undergoes compensatory adaptation to maintain absorptive capacity. The purpose of this study was to determine the relative importance of mucosal hyperplasia and functional adaptation by individual enterocytes in this process. Distal ileum was harvested from rats 2 weeks following 70% small bowel resection or transection with reanastomosis. Transport parameters were determined in Ussing chambers. Short-circuit current (Isc) responses to additions of 3-0-methylglucose were measured to assess Na+/glucose cotransporter kinetics. Microvillus absorptive surface areas were calculated with computer-assisted morphometric modeling. These surface area values were used to normalize transport parameters. Ileal absorptive surface area was 70% greater in resection tissues than in transection tissues (P < 0.05). Na+ and Cl- fluxes were generally lower in the resection group. Na+/glucose cotransporter delta Isc max (an index of cotransporter quantity) for resection and transection tissues were 0.3 +/- 0.1 and 1.8 +/- 0.3, respectively (P < 0.05). Km (an index of cotransporter affinity for substrate) did not differ significantly. Following intestinal resection, ileal surface area increases; however, transport parameters, when normalized to absorptive surface area values, diminish. During early postresection adaptation, expansion of ileal absorptive surface area due to hyperplasia seems to play a greater role than upregulation of enterocyte Na+, Cl- , and glucose absorption.

Adaptation, Physiological↗
PubMed1996

Endotoxin inhibitor prevents sepsis-induced alterations in intestinal ion transport.

BACKGROUND: The intestine is a target of septic insult. The aims of this study were to characterize sepsis-induced alterations in intestinal ion transport and to determine the role endotoxin plays in mediating these changes. METHODS: Rats underwent cecal manipulation alone (control), cecal ligation and puncture (CLP), or CLP plus intraperitoneal injection of 0.2 mg of a recently synthesized endotoxin inhibitor. At 24 hours, distal ileum was harvested, and transport parameters were determined. RESULTS: Cecal ligation and puncture produced a significant increase in short-circuit current (Isc) that was attributable to the induction of chloride secretion. There were no alterations in transepithelial resistance or fluxes of mannitol and sodium. The sepsis-induced increase in Isc was prevented by administration of the endotoxin inhibitor. CONCLUSIONS: In this model of sepsis, the primary alteration in ileal ion transport is an induction of electrogenic chloride secretion. Endotoxin inhibition may represent a strategy for prophylaxis against the intestinal effects of sepsis.

Animals↗