PubMed Health⌕ Search

Biomedical subjects

W B Wheeler

Publications and source records attributed to W B Wheeler.

At least 19 recordsLinked to original sources
PubMed2001

Management of acute pulmonary hemorrhage in children.

OBJECTIVE: Acute pulmonary hemorrhage can result from a variety of causes. This report offers a diagnosis and treatment plan for children with acute, life-threatening pulmonary hemorrhage resulting from a variety of causes. METHODS: Retrospective review of children with acute pulmonary hemorrhage cared for at a tertiary care children's hospital during from January 1, 1993 to September 1, 1999. PATIENTS: Fourteen children were identified with life-threatening pulmonary hemorrhage during the study period. INTERVENTIONS: Bronchoscopy was the keystone to diagnosis of pulmonary hemorrhage in this series. All of the children underwent multiple procedures to stabilize the airway and control blood loss. These interventions included CO2 laser bronchoscopy, Nd-YAG laser bronchoscopy, endoscopic balloon occlusion of a lobe or main bronchus, topical airway vasoconstrictors, endoscopic tumor excision, transcatheter embolization of bronchial vessels, and lobectomy. OUTCOMES: Three children died and 11 survived without neurological sequelae. CONCLUSIONS: Control of acute pulmonary hemorrhage is a difficult problem and often requires multiple procedures. Endoscopic control is usually required for palliation until more definitive therapy can be undertaken.

Acute Disease↗
PubMed2000

Potential to prevent carbon dioxide rebreathing of commercial products marketed to reduce sudden infant death syndrome risk.

OBJECTIVE: Rebreathing of exhaled air is one proposed mechanism for the increased risk for sudden infant death syndrome among prone sleeping infants. We evaluated how carbon dioxide (CO(2)) dispersal was affected by a conventional crib mattress and 5 products recently marketed to prevent prone rebreathing. SETTING: Infant pulmonary laboratory. EQUIPMENT: An infant mannequin with its nares connected via tubing to an 100-mL reservoir filled with 5% CO(2). The sleep surfaces studied included: firm mattress covered by a sheet, Bumpa Bed, Breathe Easy, Kid Safe/Baby Air, Halo Sleep System, and Sleep Guardian. The mannequin was positioned prone face-down or near-face-down. The sleep surfaces were studied with the covering sheet taut, covering sheet wrinkled, and with the mannequin arm positioned up, near the face. MEASUREMENTS: . We measured the fall in percentage end-tidal CO(2) as the reservoir was ventilated with the piston pump. The half-time for CO(2) dispersal (t(1/2)) is an index of the ability to cause or prevent rebreathing. RESULTS: Compared with the face-to-side control, 5 of 6 surfaces allowed a significant increase in t(1/2) in all 3 prone scenarios. The firm mattress and 4 of the 5 surfaces designed to prevent rebreathing consistently allowed t(1/2) above thresholds for the onset of CO(2) retention and lethal rebreathing in an animal model (J Appl Physiol. 1995;78:740). CONCLUSIONS: With very few exceptions, infants should be placed supine for sleep. For infants placed prone or rolling to the prone position, significant rebreathing of exhaled air would be likely on all surfaces studied, except one.

Bedding and Linens↗
PubMed1994

Chronic respiratory failure of infancy and childhood: clinical outcomes based on underlying etiology.

To assess whether underlying diagnosis affects morbidity and mortality outcomes in patients with chronic respiratory failure, we studied 55 patients with chronic respiratory failure of infancy and childhood (CRFIC). Entry criteria included patients with chronic respiratory failure due to static neurologic or neuromuscular conditions or secondary to other disease processes considered likely to improve or resolve over time. Subjects were grouped into those having chronic lung disease (CLD, n = 22), neurologic or neuromuscular diseases (NM, n = 21), or congenital abnormalities affecting the respiratory system (CA, n = 12). The average duration of follow-up was 21.3 months. There were no differences between groups in mortality with only four deaths (7%). Patients with CLD fared better than those with NM or CA in duration of ventilatory support, duration of tracheostomy, percentage of successful weaning from mechanical ventilation, and neurodevelopmental outcomes. Subjects with CLD had a significantly greater frequency of tracheomalacia (86%), feeding disorders (86%), and hypogammaglobulinemia G (77%). There were no differences between groups for respiratory readmissions or family dysfunction. We conclude that almost all patients with CRFIC will survive, but morbidity outcomes will vary based on the underlying diagnosis.

Child↗
PubMed1991

Genotoxicity studies of the reaction of chlorine or chlorine dioxide with L-tryptophan.

Non-volatile reaction products generated from the reactions of 70 mM aqueous chlorine or chlorine dioxide with 10 mM L-tryptophan were shown to be direct-acting mutagens to Salmonella typhimurium TA100 and TA98. Several of the fluorescent bands obtained after thin-layer chromatographic fractionation of the XAD-2/8 resin concentrates of the reaction mixtures were shown to be more mutagenic than the reaction mixtures using the Ames Salmonella/microsome assay. In addition, these fractions were shown to be capable of increasing significantly the frequency of sister chromatid exchange in Chinese hamster ovary cells in the absence of rat liver S9 mix. GC/MS analysis of the products in a highly mutagenic fraction of the aqueous chlorine reaction products identified 1,1,3-trichloropropanone, 1,1,3,3-tetrachloropropanone and dichloroquinoline.

Animals↗
PubMed1989

Bronchopulmonary dysplasia: radiographic appearance in middle childhood.

Chest radiographs were compared for three groups of children 8-9 years old: 23 survivors of bronchopulmonary dysplasia (BPD), 33 survivors of hyaline membrane disease without BPD, and 35 survivors of premature birth without neonatal respiratory problems. Only four children in the second group and three in the third had abnormal lungs. Linear shadows, apparently representing strands of fibrosis or deep pleural fissuring, were seen more frequently (15 of 23) in the BPD group than in the others (P less than .0001). Seventeen children in the BPD group had definite pulmonary abnormalities, none of them severe. The anteroposterior dimension of the chest in survivors of BPD tended to be decreased (P less than .001 vs that of reported control subjects).

Aging↗
PubMed1988

Isolation of a methyl parathion-degrading Pseudomonas sp. that possesses DNA homologous to the opd gene from a Flavobacterium sp.

Two mixed bacterial cultures isolated by soil enrichment were capable of utilizing methyl parathion (O,O-dimethyl O-p-nitrophenylphosphorothioate) and parathion (O,O-diethyl O-p-nitrophenylphosphorothioate) as a sole source of carbon. Four isolates from these mixed cultures lost their ability to utilize the pesticides independently in transfers subsequent to the initial isolation. One member of the mixed cultures, a Pseudomonas sp., however, hydrolyzed the pesticides to p-nitrophenol but required glucose or another carbon source for growth. The crude cell extracts prepared from this bacterium showed an optimum pH range from 7.5 to 9.5 for the enzymatic hydrolysis. Maximum enzymatic activity occurred between 35 and 40 degrees C. The enzyme activity was not inhibited by heavy metals, EDTA, or NaN3. Another isolate from the mixed cultures, a Flavobacterium sp., used p-nitrophenol for growth and degraded it to nitrite. Nitrite was assimilated into the cells under conditions during which the nitrogen source was excluded from the minimal growth medium. The hybridization data showed that the DNAs from a Pseudomonas sp. and from the mixed culture had homology with the opd (organophosphate degradation) gene from a previously reported parathion-hydrolyzing bacterium, Flavobacterium sp. The use of the opd gene as a probe may accelerate progress toward understanding the complex interactions of soil microorganisms with parathions.

Biodegradation, Environmental↗
PubMed1987

Reaction of chlorine dioxide with amino acids and peptides: kinetics and mutagenicity studies.

Chlorine dioxide (ClO2) is currently being considered as an alternate to chlorine as a disinfectant for water treatment. Many organic compounds present in water and food treated with ClO2 are subject to oxidation. 21 amino acids and 3 peptides (L-aspartyl-L-phenylalanine methyl ester (aspartame), L-glycyl-L-tryptophan and L-tryptophylglycine) were studied for their reactivity with ClO2. Chlorine dioxide reacted only with 6 amino acids in 0.1 M sodium phosphate buffer, pH 6.0. The reaction with cysteine, tryptophan and tyrosine was too rapid to be monitored either iodometrically or spectrophotometrically. The reaction with histidine, hydroxyproline and proline was found to be pseudo-first order. ClO2 readily reacted with L-glycyl-L-tryptophan and L-tryptophylglycine but not with aspartame. Mutagenicity studies with the Salmonella microsome assay of the reaction mixtures of ClO2 with those 6 reactive amino acids and the 3 peptides indicated that the reaction products of the 3 peptides, hydroxyproline, and tyrosine exerted mutagenic activity toward both tester strains of TA98 and TA100 in the presence and absence of rat-liver S9 mix.

Amino Acids↗
PubMed1986

Reactions of aqueous chlorine and chlorine dioxide with model food compounds.

Chlorine and chlorine dioxide (ClO2), common disinfecting and bleaching chemicals used in the food industry, are potent oxidizing and chlorinating agents. Unfortunately, little is known about the nature of the reactions of chlorine with organic food constituents. This presentation reviews published information concerning the reactions of chlorine gas (Cl2[g]), aqueous chlorine, and ClO2 with model food compounds, the fate of chlorine during the chlorination of specific food products, and the potential toxicity of the reaction products. Fatty acids and their methyl esters react with chlorine with the degree of incorporation corresponding to their degree of unsaturation. Aqueous chlorine oxidizes and chlorinates lipids and amino acids much more readily than ClO2. Several amino acids are highly susceptible to oxidation and chlorination by chlorine compounds. Reactions of chlorine and ClO2 with several food products, including flour and shrimp, have also been characterized. In one model system, 99% of Cl2(g) either reacted with components of flour or was consumed by oxidation/chlorination reactions. The lipids extracted from the chlorinated flour contained significant amounts of chlorine. Exposure of shrimp to hypochlorous acid (HOCl) solution resulted in significant incorporation of chlorine into the edible portion. Although significant quantities of chlorine can be incorporated into specific model compounds and food products, the health risks associated with exposure to chlorinated organic products are unknown. Preliminary studies using the Ames Salmonella/microsome mutagenicity assay indicate that the reaction products from mixtures of aqueous chlorine and various lipids or tryptophan are nonmutagenic. Nevertheless, additional studies are warranted, so that the toxicological significance of these reaction products can be understood more fully.

Amino Acids↗
PubMed1984

Progression of cystic fibrosis lung disease as a function of serum immunoglobulin G levels: a 5-year longitudinal study.

Seventy children with cystic fibrosis were studied over a 5-year period to assess the relationship between serum immunoglobulin G levels and progression of cystic fibrosis lung disease. Patients were grouped according to their serum IgG values (low, normal, or high) and evaluated with serial pulmonary function testing, radiographic and immunologic studies, and clinical observation. The children with persistent hypogammaglobulinemia G showed significantly better lung function, better weight for age, fewer hospitalizations for pulmonary exacerbations, less colonization with Pseudomonas aeruginosa, and slower decline in pulmonary functions than did age-matched patients with normal or high IgG levels. Death occurred in five of eight (63%) patients with hypergammaglobulinemia, three of 30 (10%) with normogammaglobulinemia, and one of 32 (3%) with hypogammaglobulinemia. No deaths occurred in the 15 patients with persistent hypogammaglobulinemia. These data indicate that children with cystic fibrosis and hypogammaglobulinemia G have milder lung disease and slower deterioration in pulmonary function than do age-matched patients with normal or elevated immunoglobulin G values. The mechanisms accounting for this finding are unclear.

Agammaglobulinemia↗
PubMed1982

Influence of various solvent-water mixtures on the extraction of dieldrin and methomyl residues from radishes.

The effect of organic solvent/water ratios on the extraction of field-incurred residues of dieldrin and methomyl from radishes was determined. 14C-Dieldrin and 14C-methomyl were applied separately to radishes in commercial formulations at rates of 0.2 and 0.9 kg/ha, respectively. Fourteen days post-application, the radishes were harvested and fresh root tissues were extracted using a Polytron homogenizer. Acetone, acetonitrile, and methanol containing 0, 10, 20, 30, 40, and 50% water were used as extraction solvents. For methomyl residues, the optimum water content of acetonitrile-water extraction mixtures was 40-50%; less than 40% water reduced the ability of acetonitrile to extract carbon-14. Methanol and acetone were nearly as efficient as 50% acetonitrile-water and were apparently not influenced by solvent/water ratios. For dieldrin, low water content slightly reduced the extraction efficiency of acetonitrile, with the optimum water content also being 40-50%. Percentage of water appeared to have little overall effect on methanol extraction efficiency. The extraction efficiency of acetone was lower than that of the other 2 solvents, and this effect was independent of the acetone/water ratio. Approximately 20% of the 14C-dieldrin residue was bound to radish roots 14 days post-application.

Acetone↗
PubMed1981

Degradation of methomyl residues in frozen strawberries.

14C-Methomyl (S-methyl N-[(methylcarbamoyl)-oxy]thioacetimidate) suspended in a commercial formulation was sprayed on strawberries. At 7 and 14 days post-application, mature berries were harvested in chopped. Fresh chopped berries were extracted with methanol using a Polytron homogenizer, and the crop marc was subsequently leached with methanol, freeze-dried, and re-extracted. Portions of the fresh chopped fruit were also frozen at-20 degrees C for 1, 30, and 102 days before extraction with methanol using a Polytron homogenizer, followed by subsequent leaching of the crop marc. For fresh berries, 93.7 and 88.9% of the 14C present at harvest was extractable at 7 and 14 days post-application, respectively. Based on thin layer chromatographic analysis, methomyl represented 83.5 and 68.2% of the 14C extracted from fresh berries at 7 and 14 days, respectively. Freezing of strawberries reduced extraction efficiency and appeared to degrade methomyl. At 7 and 14 days post-application, averages of 80.9 and 77.1%, respectively, of the 14C present were extractable after frozen storage regardless of storage time. Furthermore, only about 10% of the extracted 14C was methomyl; the remainder was of unknown composition.

Chromatography, Thin Layer↗
PubMed1980

Extraction efficiencies for pesticides in crops: 14C-benomyl extraction from mustard green and radishes.

14C-labeled benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate] suspended in a commercial benomyl formulation was sprayed on mustard greens and radishes. At 3 intervals after application, the crops were extracted with methanol, acetonitrile, or acetone. Crops were either blended and leached or repetitively blended followed by Soxhlet extraction. Essentially all of the extractable radioactivity was removed by blending. The 14C was more difficult to extract from radishes than from mustard greens as time increased. Respective percentages of 14C extracted at 1, 7, and 14 days were 99, 98, and 97 from mustard greens and 96, 88, and 79 from radishes. Methanol exhibited the highest extraction efficiency, and the blend-Soxhlet process was better than the blend-leach process. Thin layer chromatography of the organic-soluble extracts indicated that the majority of 14C was recovered as methyl 2-benzimidazole carbamate (MBC), a breakdown product of benomyl. Acid hydrolysis of the extracted tissues released 30--50% of the residual 14C.

Benomyl↗