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Biomedical subjects

C E Bagwell

Publications and source records attributed to C E Bagwell.

At least 19 recordsLinked to original sources
PubMed2006

Phylogenetic and functional biomakers as indicators of bacterial community responses to mixed-waste contamination.

Few studies have demonstrated changes in community structure along a contaminant plume in terms of phylogenetic, functional, and geochemical changes, and such studies are essential to understand how a microbial ecosystem responds to perturbations. Clonal libraries of multiple genes (SSU rDNA, nirK, nirS, amoA, pmoA, and dsrAB) were analyzed from groundwater samples (n = 6) that varied in contaminant levels, and 107 geochemical parameters were measured. Principal components analyses (PCA) were used to compare the relationships among the sites with respect to the biomarker (n = 785 for all sequences) distributions and the geochemical variables. A major portion of the geochemical variance measured among the samples could be accounted for by tetrachloroethene, 99Tc, No3, SO4, Al, and Th. The PCA based on the distribution of unique biomarkers resulted in different groupings compared to the geochemical analysis, but when the SSU rRNA gene libraries were directly compared (deltaC(xy) values) the sites were clustered in a similar fashion compared to geochemical measures. The PCA based upon functional gene distributions each predicted different relationships among the sites, and comparisons of Euclidean distances based upon diversity indices for all functional genes (n = 432) grouped the sites by extreme or intermediate contaminant levels. The data suggested that the sites with low and high perturbations were functionally more similar than sites with intermediate conditions, and perhaps captured the overall community structure better than a single phylogenetic biomarker. Moreover, even though the background site was phylogenetically and geochemically distinct from the acidic sites, the extreme conditions of the acidic samples might be more analogous to the limiting nutrient conditions of the background site. An understanding of microbial community-level responses within an ecological framework would provide better insight for restoration strategies at contaminated field sites.

Bacteria↗
PubMed2004

Coupling of functional gene diversity and geochemical data from environmental samples.

Genomic techniques commonly used for assessing distributions of microorganisms in the environment often produce small sample sizes. We investigated artificial neural networks for analyzing the distributions of nitrite reductase genes (nirS and nirK) and two sets of dissimilatory sulfite reductase genes (dsrAB1 and dsrAB2) in small sample sets. Data reduction (to reduce the number of input parameters), cross-validation (to measure the generalization error), weight decay (to adjust model parameters to reduce generalization error), and importance analysis (to determine which variables had the most influence) were useful in developing and interpreting neural network models that could be used to infer relationships between geochemistry and gene distributions. A robust relationship was observed between geochemistry and the frequencies of genes that were not closely related to known dissimilatory sulfite reductase genes (dsrAB2). Uranium and sulfate appeared to be the most related to distribution of two groups of these unusual dsrAB-related genes. For the other three groups, the distributions appeared to be related to pH, nickel, nonpurgeable organic carbon, and total organic carbon. The models relating the geochemical parameters to the distributions of the nirS, nirK, and dsrAB1 genes did not generalize as well as the models for dsrAB2. The data also illustrate the danger (generating a model that has a high generalization error) of not using a validation approach in evaluating the meaningfulness of the fit of linear or nonlinear models to such small sample sizes.

Bacteria↗
PubMed2001

Recovery and phylogenetic analysis of nifH sequences from diazotrophic bacteria associated with dead aboveground biomass of Spartina alterniflora.

DNA was extracted from dry standing dead Spartina alterniflora stalks as well as dry Spartina wrack from the North Inlet (South Carolina) and Sapelo Island (Georgia) salt marshes. Partial nifH sequences were PCR amplified, the products were separated by denaturing gradient gel electrophoresis (DGGE), and the prominent DGGE bands were sequenced. Most sequences (109 of 121) clustered with those from alpha-Proteobacteria, and 4 were very similar (>99%) to that of Azospirillum brasilense. Seven sequences clustered with those from known gamma-Proteobacteria and five with those from known anaerobic diazotrophs. The diazotroph assemblages associated with dead Spartina biomass in these two salt marshes were very similar, and relatively few major lineages were represented.

Alphaproteobacteria↗
PubMed2000

Myofibroblast induction with transforming growth factor-beta1 and -beta3 in cutaneous fetal excisional wounds.

BACKGROUND/PURPOSE: In a noncontractile fetal rabbit model, the authors recently have shown the induction of excisional wound contraction with sustained-release cellulose implants formulated with transforming growth factor (TGF)-beta. The purpose of this study was to test the hypothesis that the excisional wound contraction in this model is associated with the induction of myofibroblasts in the surrounding dermis, demonstrated by the presence of alpha-smooth muscle actin. METHODS: Cellulose discs were formulated with either 1.0 microg of TGF-beta1 (n = 6); 1.0 microg of TGF-beta3 (n = 9); 10 microg of TGF-beta3 (n = 6); or their carrier protein, bovine serum albumin (BSA; n = 9), for sustained-release over 5 days. Each disc was implanted into a subcutaneous pocket on the back of a fetal New Zealand White rabbit in utero on day 24 of gestation (term, 31 days). A full-thickness, 3-mm excisional wound (7.4 mm2) was then made next to the implanted cellulose disc. All fetuses were harvested at 3 days. The amount of alpha-smooth muscle (SM) actin in the dermis around the implants and wounds was determined using immunohistochemical techniques. RESULTS: Excisional wounds exposed to 1.0 microg of TGF-beta1 (5.6+/-2.0 mm2), 1.0 microg of TGF-beta3 (6.9+/-1.0 mm2), and 10 microg of TGF-beta3 (2.7+/-1.0 mm2) were significantly smaller when compared with the BSA control group (12.8+/-1.1 mm2; P<.05). Furthermore, there was a significant increase in staining for alpha-SM actin in the TGF-beta1 (1.8+/-0.5) and 10 microg TGF-beta3 (2.8+/-0.2) groups in comparison with the scant staining in the BSA control group (0.5+/-0.2; P<.05). CONCLUSIONS: TGF-beta1 and -beta3 induce alpha-SM actin and contraction of cutaneous excisional wounds in a fetal noncontractile model. This model of inducible cutaneous excisional wound contraction may be useful in further determining the role of the myofibroblast in wound contraction and the physiology underlying this poorly understood aspect of wound healing.

Actins↗
PubMed2000

Preoperative staging, prognostic factors, and outcome for extremity rhabdomyosarcoma: a preliminary report from the Intergroup Rhabdomyosarcoma Study IV (1991-1997).

BACKGROUND: During the fourth Intergroup Rhabdomyosarcoma (RMS) Study (IRS IV, 1991-97), a preoperative staging system was evaluated prospectively for the first time. The authors evaluated this staging system and the role of surgery in extremity RMS in contemporary multimodal therapy. METHODS: A total of 139 patients (71 girls; median age, 6 years) were entered in IRS IV with extremity-site RMS. Stage was assigned by the IRSG Preoperative Staging System. Postsurgical group was determined by tumor status after initial surgical intervention. Multivariate analysis was performed using all pretreatment factors that were significant by univariate analysis, including clinical Group (i.e., I through IV), tumor invasiveness (T1,T2), nodal status (N0,N1), and tumor size (< or > or =5 cm). Failure-free survival rates (FFS) and survival rates were estimated using the Kaplan and Meier method. RESULTS: Preoperative staging and clinical group distribution were as follows: Stage 2, n = 34; Stage 3, n = 73; Stage 4, n = 32; Group I, n = 31; Group II, n = 21; Group III, n = 54; Group IV, n = 33. Three-year FFS was 55%, and the overall survival rate was 70%. Eighty-seven patients had either unresectable, gross residual disease (Group III) or metastases (Group IV). FFS was significantly worse for these patients with advanced disease, compared with that for patients with complete resection or with only microscopic residual tumor (i.e., Group I or II; Group I, 3-year FFS, 91%; Group II, 72%; Group III, 50%; Group IV, 23%; P<.001). Lymph nodes were evaluated surgically in 76 patients with positive results in 38. Clinically, 13 additional patients had nodal disease. Both stage and group were highly predictive of outcome and were highly correlated. By multivariate analysis, none of the other variables were predictors of FFS. CONCLUSIONS: This review confirms the utility of pretreatment staging for stratification of patients with extremity RMS with widely different risks of relapse, thereby paving the way for development of risk-based therapy. Group (operative staging) remains the most important predictor of FFS, emphasizing the importance of complete gross resection at initial surgical intervention, when feasible without loss of limb function. The high incidence of nodal disease in the patients who had lymph node biopsy confirms the need for surgical evaluation of lymph nodes to ensure accurate staging in children with extremity rhabdomyosarcoma.

Child↗
PubMed2000

Potentially lethal complications of central venous catheter placement.

BACKGROUND: Placement of central venous catheters, although often considered to be a relatively safe and "junior"-level procedure, may be associated with life-threatening complications. METHODS: A recent surgical death associated with placement of a central venous catheter at this Institution led to submission of a questionnaire to pediatric surgeons referenced through the American Pediatric Surgical Association directory regarding knowledge of similar incidents and information regarding catheter placement-related complications. RESULTS: Results to this response, although anecdotal, provided data regarding complications of an acute nature, which fell into the categories of pneumothorax, hydrothorax, cardiac tamponade, and hemothorax. Of 10 children with cardiac tamponade, 7 were infants, and most complications were associated with needle stick for access, with symptoms developing within minutes up to 12 hours after the procedure. Drainage of the tamponade was performed by aspiration alone in 3 cases; surgical drainage in 6 children resulted in survival in 9 of the 10 patients. Hemothorax was described in 19 patients and appeared to be more common in children in the 1- to 6-year age group, usually associated with percutaneous access techniques. Thoracotomy for hemothorax was performed in 16 children with 11 survivors. Vascular injury to subclavian artery, vein, or superior vena caval were noted in most at operation. CONCLUSIONS: Although data included in this review are entirely anecdotal and not subject to scientific scrutiny or analysis, certain conclusions appear evident. Inherent risks of central venous catheters are intrinsic and should be discussed with the family in obtaining preoperative consent, including life-threatening risks that may necessitate urgent surgical intervention (by thoracotomy or other means). Certain technical aspects of the procedure should be rigidly followed with an experienced surgeon in attendance throughout the procedure. Rapid evaluation should be performed for any unexplained problems that occur in the operating theatre or during the early postoperative period.

Age Distribution↗
PubMed2000

Persistence of selected Spartina alterniflora rhizoplane diazotrophs exposed to natural and manipulated environmental variability.

Rhizoplane-rhizosphere nitrogen-fixing microorganisms (diazotrophs) are thought to provide a major source of biologically available nitrogen in salt marshes dominated by Spartina alterniflora. Compositional and functional stability has been demonstrated for this important functional group; however, the quantitative responses of specific diazotroph populations to environmental variability have not been assessed. Changes in the relative abundances of selected rhizoplane diazotrophs in response to long-term fertilization were monitored quantitatively by reverse sample genome probing. Fertilization stimulated Spartina, with plant height nearly tripling after 1 year. Fertilization also resulted in significant changes in interstitial porewater parameters. Diazotrophic activity (acetylene reduction assay) was sensitive to the fertilization treatments and was inhibited in some plots on several sampling dates. However, inhibition was never consistent across all of the replicates within a treatment and activity always recovered. The rhizoplane diazotrophs were quite responsive to environmental variability and to experimental treatments, but none were displaced by either environmental variability or experimental treatments. All strains were detected consistently throughout this study, and extensive spatial heterogeneity in the distribution patterns of these organisms was observed. The physiological traits that differentiate the diazotroph populations presumably support competitiveness and niche specialization, resulting in the observed resilience of the diazotroph populations in the rhizosphere.

Acetylene↗
PubMed2000

Molecular analysis of diazotroph diversity in the rhizosphere of the smooth cordgrass, Spartina alterniflora.

N(2) fixation by diazotrophic bacteria associated with the roots of the smooth cordgrass, Spartina alterniflora, is an important source of new nitrogen in many salt marsh ecosystems. However, the diversity and phylogenetic affiliations of these rhizosphere diazotrophs are unknown. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified nifH sequence segments was used in previous studies to examine the stability and dynamics of the Spartina rhizosphere diazotroph assemblages in the North Inlet salt marsh, near Georgetown, S.C. In this study, plugs were taken from gel bands from representative DGGE gels, the nifH amplimers were recovered and cloned, and their sequences were determined. A total of 59 sequences were recovered, and the amino acid sequences predicted from them were aligned with sequences from known and unknown diazotrophs in order to determine the types of organisms present in the Spartina rhizosphere. We recovered numerous sequences from diazotrophs in the gamma subdivision of the division Proteobacteria (gamma-Proteobacteria) and from various anaerobic diazotrophs. Diazotrophs in the alpha-Proteobacteria were poorly represented. None of the Spartina rhizosphere DGGE band sequences were identical to any known or previously recovered environmental nifH sequences. The Spartina rhizosphere diazotroph assemblage is very diverse and apparently consists mainly of unknown organisms.

Bacteria, Anaerobic↗
PubMed1999

Plasma intestinal fatty acid binding protein in neonates with necrotizing enterocolitis: a pilot study.

BACKGROUND/PURPOSE: Intestinal fatty acid-binding protein (IFABP) is found within cells at the tip of the intestinal villi, an area commonly injured when necrotizing enterocolitis (NEC) occurs. This study was undertaken to determine if measuring IFABP concentrations in the bloodstream early in the course of NEC would differentiate patients by severity before clinical findings made it clear who had stage 3 NEC and who had milder stages. METHODS: Three plasma samples from newborn infants evaluated for NEC were obtained at symptom onset and after 8 and 24 hours. IFABP concentration was measured by radioimmunoassay. Infants were classified by the final and most severe stage of NEC, and IFABP levels were compared between groups at each sampling. RESULTS: IFABP was detectable in blood samples from all 7 infants with stage 3 NEC compared with 3 of 24 with stages 1 or 2 NEC. Elevated plasma IFABP concentrations were detectable before clinical staging could be made in 5 of the 7 subjects with stage 3 NEC. CONCLUSION: IFABP may be a specific marker for early identification of severe NEC.

Biomarkers↗
PubMed1999

Circulating pro- and counterinflammatory cytokine levels and severity in necrotizing enterocolitis.

OBJECTIVES: To evaluate the relationship between the severity of necrotizing enterocolitis (NEC) and circulating concentrations of proinflammatory cytokines interleukin (IL)-1beta and IL-8 and counterinflammatory cytokines IL-1 receptor antagonist (IL-1ra) and IL-10. These cytokines have been associated with bowel injury or inflammation and may be released more slowly or later than previously examined cytokines. Also, to determine if any one of these cytokines will predict the eventual severity of NEC when measured at symptom onset. METHOD: Serial blood samples at onset, 8, 24, 48, and 72 hours were obtained from newborn infants with predefined signs and symptoms of NEC. Normal levels were defined from weight-, gestation-, and age-matched controls. Concentrations of the four cytokines were determined by enzyme-linked immunosorbent assay and compared throughout the time period by stage of NEC, using sepsis as a co-factor. Mean concentrations of each cytokine at onset were compared with the controls. Threshold values were obtained with the best combination of high sensitivity and high specificity for defining stage 1 NEC or for diagnosing stage 3 NEC at onset. RESULTS: There were 12 cases of stage 1, 18 cases of stage 2, and 6 cases of stage 3 NEC included in the study, as well as 20 control infants. Concentrations of IL-8 and IL-10 were significantly higher in infants with stage 3 NEC from onset through 24 hours compared with infants with less severe NEC. At onset, concentrations of all four cytokines were significantly higher in stage 3 NEC. To identify, at onset, the infants with a final diagnosis of stage 3 NEC, an IL-1ra concentration of >130 000 pg/mL had a sensitivity of 100% and a specificity of 92%. At 8 hours, an IL-10 concentration of >250 pg/mL had a sensitivity of 100% and a specificity of 90% in identifying stage 3 NEC in infants with symptoms suggestive of NEC at onset. CONCLUSIONS: The severity of NEC and its systemic signs and symptoms are not due to a deficiency of counterregulatory cytokines. In fact, mean concentrations of IL-1ra in NEC are higher than what has been reported in other populations. The cytokines IL-8, IL-1ra, and IL-10 are released later or more slowly after a stimulus and may be more useful in identifying, within hours of symptom onset, which infant will develop significant NEC.

Enterocolitis, Necrotizing↗
PubMed1998

Physiological diversity of the rhizosphere diazotroph assemblages of selected salt marsh grasses.

Rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. Several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. This geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these organisms. The diversity and key physiological features of culturable, O2-tolerant rhizosphere diazotrophs associated with the tall and short growth forms of Spartina alterniflora and with Juncus roemerianus were examined. A total of 339 gram-negative strains were isolated by a root stab culture approach and morphologically and physiologically characterized by using API and BIOLOG tests. Eighty-six distinct groups composed of physiologically similar strains were identified. Of these groups, 72% were shown to be capable of N2 fixation through molecular analyses, and a representative strain was chosen from each diazotroph group for further characterization. Cluster and principal-components analysis of BIOLOG data allowed the designation of physiologically distinct strain groupings. Most of these groups were dominated by strains that were not identifiable to species on the basis of API or BIOLOG testing. Representatives of several families including the Enterobacteriaceae, Vibrionaceae, Azotobacteraceae, Spirillaceae, Pseudomonadaceae, and Rhizobiaceae were recovered, as well as strains with no clear taxonomic affiliations. This study identifies numerous potentially important physiological groups of the salt marsh diazotroph assemblage.

Bacteria↗
PubMed1996

The argument for conservative, delayed surgery in the management of prostatic rhabdomyosarcoma.

Exenteration is no longer required for most patients who have rhabdomyosarcoma (RMS) of the prostate. This site comprised only about 5% of newly diagnosed cases in the IRS-III (1984-1991). The mean age at the time of diagnosis was 5.3 yrs (range, 0 to 19 years). Most tumors were relatively large, had embryonal histology, and were clinically localized but unresectable without major loss of organ function. The 44 patients with group III tumors (gross residual disease) were treated according to the IRS-III protocol. Forty-three of them underwent biopsy only, and one patient had subtotal resection as the initial procedure. The average number of surgical procedures per patient was two (range, one to five). Six of the 44 patients had no additional surgery. The second-look procedures performed in the other 38 patients included exenteration (14), prostatectomy (7), cystoscopic/perineal needle biopsy (8), laparotomy with biopsy (6), and subtotal excision with bladder salvage (3). Additional surgery was required for four patients, for evaluation of a residual mass, postoperative fistula, ureteral stricture, or small bowel obstruction. Six patients with relapse or residual disease underwent additional chemotherapy and late exenteration (3), prostatectomy (1), or biopsy (2). Four of the six have been cured, one is in treatment for a second malignancy, and the other has residual disease after exenteration. Thirty-six of the 44 patients with group III tumors have been cured (minimum follow-up period, 6 years; range, 6 to 11 years), compared with 23 of the 47 in IRS-II (1978-1984) (P = .001). Two of the six deaths in this group were caused by infection. The bladder salvage rate for those cured of their disease also was better (64% v 57% for IRS-II). The two patients with group IIA tumors were cured by gross primary excision, local radiotherapy, and vincristine and actinomycin therapy. By contrast, all patients with metastatic disease (group IV) died of the tumor. Conservative, delayed surgery, performed after intensive chemotherapy with or without radiotherapy, yields a better cure rate while maintaining a high rate of bladder salvage in children with group III prostatic RMS.

Adolescent↗
PubMed1995

Unilateral pulmonary agenesis, esophageal atresia, and distal tracheoesophageal fistula.

A small-for-gestational-age, premature infant with the combination of unilateral pulmonary agenesis, esophageal atresia, and distal tracheoesophageal fistula was treated successfully by early gastrostomy and delayed fistula division with esophagoesophagostomy. Only 2 other successfully treated cases have been reported previously. Both were full-term infants treated with early division of the tracheoesophageal fistula and esophagoesophagostomy. Gestational age, size, and associated medical problems need to be considered when planning operative therapy for these babies.

Abnormalities, Multiple↗
PubMed1995

Long-term venous access using endogenous splenic tissue: the 'spleen-o-port'.

The authors sought to determine whether endogenous splenic tissue placed in a subcutaneous pouch ("spleen-o-port") could function as a viable alternative to central venous catheters/ports for long-term venous access. A small transverse incision was made in the left upper quadrant of each puppy (n = 6) under general anesthesia. Using a stapler, the authors divided the splenic parenchyma. The superior portion was returned to its native location, and a subcutaneous pocket was created to house the inferior pole with its attached vascular supply. The fascial and muscular layers were closed with care to avoid compressing the blood supply to the spleen-o-port. Postoperatively the dogs resumed normal activity. There have been no deaths, infectious complications, splenic ruptures, or thromboses over a 6-month period. Under fluoroscopy, the dogs were imaged from postoperative day (POD) 10 to 177. Contrast agent entering the splenic parenchyma was promptly visualized in the splenic vein and then filled the portal vein. Electrolyte measurements from spleen-o-port blood samples were identical to those from peripheral venous samples. After gentamicin (mixed in a crystalloid solution) was infused through the spleen-o-port, the peak serum level corresponded to the therapeutic levels observed after standard intravenous administration. The spleen-o-port permits rapid infusion of drugs and crystalloid, and allows repetitive blood sampling while eliminating the foreign body that can promote septicemia in the immunocompromised patient.

Animals↗
PubMed1995

Management of persistent pediatric tracheostomal fistulas.

Decannulation of a tracheostomy generally results in spontaneous closure. Occasionally, epithelialization results in persistence of the fistula, which may be initially treated by local curettage or cautery. Failure of these methods constitutes an indication for surgical closure. Dissection of the entire tracheocutaneous tract permits fistula closure in juxtaposition to but outside the trachea and prevents any iatrogenic airway narrowing. Twelve patients have been so managed over the last 10 years, and there have been no immediate or long-term complications.

Child↗
PubMed1995

Gastroesophageal reflux in children.

Whereas all of these surgical modifications and new approaches are somewhat preliminary and have yet to achieve widespread clinical application, they illustrate an awareness of shortcomings in the present operative management of reflux as well as a gradual disenchantment with complications seen in many children, especially the neurologically impaired. However, the final analysis of surgical treatment for these children should not be viewed in an overly pessimistic light. Strategies for management of gastroesophageal reflux remain multifaceted, and operative intervention has a laudable role in the relief of symptoms for many afflicted children. However, the child's presentation and symptomatology should be predominant in planning therapy, operative or otherwise. It is the goal of this review to point out several points in this respect: 1. The diagnosis of gastroesophageal reflux may be difficult to pinpoint. 2. Multiple tests for reflux may offer conflicting results. 3. Clinical presentations associated with reflux do respond to treatment, which may include operative intervention. 4. The risks of anti-reflux procedures are greater than have been previously recognized, especially in the chronically ill and neurologically impaired child. 5. New approaches offer some promise to lower the risks of complications inherent in operative treatment of pathologic gastroesophageal reflux. 6. The best management plan for surgical treatment of reflux in children is evolving with less of a conviction for "prophylactic" fundoplication procedures, especially in the neurologically impaired child, and there is a recognition that underlying motility disorders may require modification of the operative approach or even the decision to operate. It is only through an awareness of the significant benefits as well as the considerable risks of operative treatment that the contemporary surgeon can best serve the interests of a child with gastroesophageal reflux. It is hoped that these guidelines will be helpful in this regard.

Adolescent↗