Biomedical subjects

D Campbell

Publications and source records attributed to D Campbell.

At least 145 records · Page 8Linked to original sources

PubMed1996

A method for estimating respiratory muscle efficiency using an automated metabolic cart.

We measured respiratory muscle efficiency (RME) in twelve healthy human subjects by dividing the added energy cost of breathing against a threshold resistance load by the associated increase in caloric expenditure. Caloric expenditure was calculated using steady-state measurements of oxygen consumption and carbon dioxide production during loaded and unloaded breathing. Calculated RME ranged from 1.7% to 5.5% (mean 3.5%). The coefficient of variation in six subjects averaged 13%. We compared these calculations with a previously described oxygen consumption-based method that did not incorporate carbon dioxide production measurements. We found that changes in the respiratory quotient during resistive breathing could cause significant errors in oxygen consumption-based calculations of RME. Limits of agreement of 95% suggest that the oxygen-consumption-based calculations could potentially overestimate efficiency by as much as 5.0% or underestimate by up to 3.4%. We recommend that carbon dioxide production be measured when this technique for estimation of RME is used. This can be easily accomplished through the use of an automated metabolic cart.

Adult↗

PubMed1996

DNAM-1, a novel adhesion molecule involved in the cytolytic function of T lymphocytes.

Intercellular adhesion molecules play an important role in the generation of T lymphocyte-mediated immune responses. Here, we describe a novel accessory molecule, DNAX accessory molecule-1 (DNAM-1), that is constitutively expressed on the majority of peripheral blood T lymphocytes. DNAM-1 is a 65 kDa transmembrane glycoprotein consisting of 318 aa including two immunoglobulin-like domains. Anti-DNAM-1 monoclonal antibody (MAb) inhibits T and NK cell-mediated cytotoxicity against a variety of tumor cell targets and blocks cytokine production by alloantigen-specific T cells. In addition, DNAM-1 is a tyrosine-phosphorylated signal-transducing molecule that participates in primary adhesion during cytotoxic T lymphocyte (CTL)-mediated cytotoxicity.

Amino Acid Sequence↗

PubMed1996

Unrecognized "crack" cocaine abuse in pregnancy.

We report a case of "crack" cocaine abuse in a pregnant patient associated with haematuria, proteinuria, haemolytic anaemia, renal impairment, thrombocytopenia and pulmonary oedema. The case illustrates the problems for clinicians where unrecognized cocaine abuse interferes with the diagnosis and management of a complicated pregnancy. In addition, we discuss the principles for the safe conduct of anaesthesia in the pregnant cocaine abuser.

Adult↗

PubMed1996

Repositioning the stoma of the cervical esophagostomy.

The stoma created with a diverting cervical esophagostomy is often an unsightly inconvenience for the patient because of the high incidence of leakage from the collecting appliance. Secure attachment of a collection device at the base of the neck is difficult. The stoma of the cervical esophagostomy may be moved away from the base of the neck using a tubed skin flap modeled after that originally described by Wookey. Such a procedure has the advantages of removing the appliance from an area of high visibility and providing a flatter base that decreases leakage and soiling. We advocate this simple procedure in patients who desire to rid themselves of a cervical appliance, but who are poor operative candidates for a more extensive procedure replacing the entire esophagus.

Esophagostomy↗

PubMed1996

Effects of availability of patient-related charges on practice patterns and cost containment in the pediatric intensive care unit.

OBJECTIVE: To investigate the effects of the availability of daily patient-related charges to healthcare providers on practice patterns and cost containment in the pediatric intensive care unit (ICU) setting. DESIGN: Prospective, nonrandomized, controlled trial. SETTING: Pediatric ICU. PATIENTS: All patients admitted to the pediatric ICU during the study period. This number included a prospective control group (n=325) and an intervention group (n=273). These 598 patients spent 2,274 patient days in the pediatric ICU. INTERVENTIONS: The daily itemized patient charges related to diagnostic studies ordered in the pediatric ICU were made available to healthcare providers during the intervention period of the study. MEASUREMENTS AND MAIN RESULTS: Information was collected prospectively on patients in the control group before the intervention period. This information included data on demographics, daily severity of illness measures, daily resource consumption, intensity of nursing and medical interventions, and daily patient-related charges. Outcome information on survival and length of pediatric ICU stay was also collected. The same data were collected prospectively during the intervention period of the study. Measurements on quality assurance and morbidity were made to ensure that there was no compromise in patient care. There were no significant differences in patient demographics and diagnoses between the control and intervention groups. There was a reduction in the average daily laboratory (16.7%), radiology (9.1%) computerized axial tomography (8.5%), and pharmacy (25.1%) charges in the intervention group as compared with controls. The decreases in laboratory and pharmacy charges were statistically significant (p<.0001). The decreases in laboratory and pharmacy charges remained significant even after adjustment for severity of illness. CONCLUSIONS: The availability of patient-related charges to healthcare providers can result in changes in practice patterns, producing a decrease of patient charges and an improvement in cost containment in the pediatric ICU.

Analysis of Variance↗

PubMed1996

Endoscopic management of a bronchobiliary fistula.

A bronchobiliary fistula is a rare entity that manifests as bilioptysis. We report a 73-year-old woman with a hepato-cellular carcinoma who developed a bronchobiliary fistula. Endoscopic biliary sphincterotomy and insertion of a prosthesis led to successful resolution of symptoms and restoration of normal bile flow. We review the pertinent literature and the basis for management.

Aged↗

PubMed1996

Inactivation of the petE gene for plastocyanin lowers photosynthetic capacity and exacerbates chilling-induced photoinhibition in the cyanobacterium Synechococcus.

We describe the identification and expression of a petE gene in Synechococcus sp. PCC 7942, a cyanobacterium previously thought to lack plastocyanin. The petE gene is a 420-bp open reading frame that encodes a protein 70 to 75% similar to plastocyanins from other cyanobacteria. Synechococcus possesses a single genomic copy of petE located immediately upstream of the clpB gene. It is transcribed as a single mRNA (550 bases) and, in contrast to most other photobionts, the level of petE expression in Synechococcus is unaffected by variable copper concentrations during acclimated growth. Inactivation of petE does not prevent photoautotrophic growth, but does induce a dramatic increase in mRNA for the alternative electron carrier cytochrome C6. Despite this adjustment, loss of plastocyanin results in slower growth, lower photosystem I content, and a decreased maximum capacity for photosynthetic electron transport. The mutant is also more susceptible to chilling-induced photoinhibition during a shift from 37 to 25 degrees C, at which temperature its inherently lower photosynthetic capacity exacerbates the normal slowing of electron transfer reactions at low temperatures. Under similar conditions, the amount of petE message in the wild type decreases by 50% in the 1st h, but then increases dramatically to almost three times the 37 degrees C level by 9 h.

Amino Acid Sequence↗

PubMed1996

Requirements for interleukin-4-induced gene expression and functional characterization of Stat6.

Interleukin-4 (IL-4) stimulation leads to the activation of the signal transducer and activator of transcription 6 (Stat6). In this study, we present data relating to the functional properties of Stat6. Human embryonic kidney 293 cells were shown to be deficient of Stat6 yet express all other components of the IL-4 signaling cascade. This cell line was used for transient-transfection studies of wild-type and mutant Stat6 proteins. The wild-type protein was shown to activate a reporter construct carrying multiple copies of the IL-4 response element derived from the human immunoglobulin heavy-chain germ line epsilon promoter. Similarly, a truncated protein lacking 41 amino acids of the N terminus was fully active. However, removal of the C-terminal 186 amino acids completely abolished transcription activation. Amino acid substitutions were introduced into the putative DNA binding domain (VVI at positions 411 to 413), the SH2 domain (R-562), or the tyrosine (Y-641) which presumably becomes phosphorylated upon activation. All three of these Stat6 mutants were unable to activate transcription in 293 cells. Wild-type and mutant Stat6 derivatives were also expressed in insect cells, and purified proteins were analyzed in vitro for the ability to interact with both DNA and tyrosine-phosphorylated peptides derived from the IL-4 receptor alpha chain. Mutations within the DNA binding domain, the SH2 domain, or tyrosine 641 completely abolished DNA binding. In contrast, only the SH2 mutant failed to interact with tyrosine-phosphorylated peptides. The transdominant effects of all Stat6 derivatives were analyzed by using HepG2 cells, which express endogenous Stat6 protein. Differential effects were observed with various mutants, supporting the current model of the Jak/STAT activation cycle.

Amino Acid Sequence↗

PubMed1996

Mental health supplement to the Ontario Health Survey: methodology.

OBJECTIVE: To describe the methodology of a province-wide, cross-sectional, epidemiologic study of psychiatric disorder among those aged 15 years and over living in household dwellings in Ontario. METHOD: Respondents for the survey were drawn from households (N = 13002) participating in a province-wide health survey. One person per household was selected, and 9953 (76.5%) participated. RESULTS: Participants and nonparticipants were similar to each other. An extensive array of data, including measures of psychiatric disorder classified using a revised version of the Composite International Diagnostic Interview (CIDI), are available for all respondents. CONCLUSIONS: The Ontario Health Supplement is contained in a public-use data file at the Ontario Ministry of Health and is available to investigators for study. A strong survey design, careful measurement, and acceptable levels of response provide the rationale for our inviting researchers to access and use the Ontario Health Supplement data base.

Adolescent↗

PubMed1996

One-year prevalence of psychiatric disorder in Ontarians 15 to 64 years of age.

OBJECTIVE: To present the one-year prevalence of 14 psychiatric disorders in a community sample of Ontarians aged 15 to 64 years. METHOD: Data on psychiatric disorders were collected on 9953 respondents using the University of Michigan revision of the Composite International Diagnostic Interview (UM-CIDI). DSM-III-R criteria were used to define the psychiatric disorders. RESULTS: Almost 1 in 5 Ontarians (18.6%) had one or more of the disorders measured in the survey. Among 15-to 24-year-olds, 1 in 4 was affected. The distribution of individual disorders varied by sex and age. CONCLUSION: Because of the immense burden of suffering associated with psychiatric disorders, clinical and research efforts in this area should receive high priority within the health budget.

Adolescent↗

PubMed1996

The use of mental health services in Ontario: epidemiologic findings.

OBJECTIVE: To describe the distribution and predictors of mental health service use for a survey of Ontario household residents aged 15 to 64 years. METHOD: Service use was defined as any past-year contact with formal or informal health care providers for mental health reasons. Data from the Mental Health Supplement (the Supplement) to the Ontario Mental Health Survey were used to compare the sociodemographic, geographic, and diagnostic status characteristics of service users with these characteristics among nonusers. RESULTS: Mental health services were used by 7.8% of respondents in the past year. The majority (57.8%) had a past-year University of Michigan Composite International Diagnostic Interview (UM-CIDI) diagnosis, although 27.1% had never met diagnostic criteria. Other significant predictors were marital status, household public assistance, gender, age, and urban/rural residence. CONCLUSION: Although diagnosis is the strongest predictor of use, the fit between "need" and "care" in Ontario is not perfect. Help seeking differs within specific sociodemographic and geographic groups. Furthermore, the association of marital disruption and economic disadvantage with utilization indicates that prevention and intervention should address needs beyond the medical or psychological.

Adolescent↗

PubMed1996

Theophylline improves measurements of respiratory muscle efficiency.

To determine the effect of theophylline on respiratory muscle efficiency (RME), 12 normal subjects were given theophylline vs placebo in a double-blind, randomized crossover protocol. Spirometry, resting energy expenditure, minute ventilation, RME and oxygen cost of breathing were measured at baseline, after taking theophylline, and after placebo. RME was calculated by dividing the added work required to breathe through a threshold load by the added energy consumed during loaded breathing. Oxygen cost of breathing was calculated by dividing the increase in oxygen consumption induced by breathing an air/carbon dioxide mixture by the associated increase in minute ventilation. RME increased from 3.3 +/- 1.6% at baseline to 7.9 +/- 3.2% after theophylline (p < 0.01) but did not change significantly after placebo (4.8 +/- 2.4%). Oxygen cost of breathing decreased from 3.9 +/- 2.4 mL O2 per liter at baseline to 1.7 +/- 0.7 mL O2 per liter after theophylline (p < 0.05) but did not change significantly after placebo (2.8 +/- 1.3 mL O2 per liter). Theophylline use was also associated with an 18% increase in minute ventilation (p < 0.01) and a 15.7% increase in resting energy expenditure (p < 0.01). Theophylline improves measured RME and reduces oxygen cost of breathing in normal subjects. These effects are offset by increases in resting energy expenditure and minute ventilation.

Adult↗

PubMed1996

Routine perioperative dipyridamole 201Tl imaging in diabetic patients undergoing vascular surgery.

OBJECTIVE: To assess the utility of dipyridamole thallium testing in symptomatic and asymptomatic patients with diabetes undergoing vascular surgery. RESEARCH DESIGN AND METHODS: Dipyridamole 201Tl myocardial scintigraphy was performed preoperatively in 93 consecutive patients with diabetes undergoing peripheral vascular procedures. The utility of clinical and thallium variables in predicting cardiovascular complications was assessed. RESULTS: Two groups of patients were identified: group A (36 patients) without clinical evidence of cardiac disease and group B (57 patients) with clinical evidence of cardiac disease. Dipyridamole thallium scans were abnormal in 21 of 36 (58%) of group A patients compared with 53 of 57 (93%) of group B patients (P < 0.0001). Compared with group B patients with perfusion defects, group A patients with perfusion abnormalities tended to have fewer defects per scan (2.7 +/- 1.5 vs. 3.6 +/- 1.9, P = 0.05). No perioperative cardiac complications occurred in group A patients while perioperative cardiac complications occurred in 9 of 57 (16%, 95% CI 7-28%) group B patients (P = 0.01). For the entire study population, the complication rate was 10%. CONCLUSIONS: Diabetic individuals without clinical markers for coronary artery disease appear to be at low risk for adverse postoperative cardiac events after vascular surgery. Preoperative myocardial perfusion imaging may add little to cardiovascular risk assessment in this subgroup of patients with diabetes.

Aged↗

PubMed1996

The quantitation of metabolites of quercetin flavonols in human urine.

The flavonoid quercetin, or its metabolites, inhibit chemical carcinogenesis in rodents and may have a role in the prevention of human cancers. Quercetin exposure in human populations results from the dietary intake of various plant foods; high concentrations of quercetin are found in apples, onions, tea, and red wine. Determination of the relationship between dietary intake and cancer risk depends on the characterization of quercetin intake. The development and use of biomarkers for quercetin intake may provide a basis for the objective classification of this exposure. One possible biomarker is metabolic products of quercetin. We report the development of a high-performance liquid chromatography (HPLC)-based assay for quantitation of quercetin metabolites in human urine. The metabolites include 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid), metahydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid (homovanillic acid). The assay has only two major steps, ether extraction and HPLC analysis, and is suitable for analysis of large sample numbers. Analytical characteristics of the assay include a sensitivity of less than 1 microgram, precision with coefficients of variation < 10%, and metabolite recoveries > 90%. The mean concentrations of 3,4-dihydroxyphenylacetic acid, metahydroxyphenylacetic acid, and homovanillic acid in two human urine samples are approximately 0.7, 4.8, and 2.8 micrograms/ml, respectively. The identification of each metabolite is confirmed by HPLC, UV absorbance scans, and gas chromatography-mass spectrometry analysis. These results verify the occurrence of quercetin metabolites in human urine and the feasibility of quercetin metabolite quantitation, by the assay described herein, for epidemiological studies. Development of the analytical procedure is an essential first step for validation of the metabolites as biomarkers of quercetin intake.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1996

Psychiatric disability in Ontario.

OBJECTIVE: To describe the disability associated with psychiatric disorder in a community sample in order to refine estimates of service need and identify subgroups with greater priority for intervention. METHOD: Disability is conceptualized broadly as performance difficulties, troubled relationships, and dissatisfaction in various life domains. Data from the Mental Health Supplement are used to compare disability between those with and without disorder and among various subtypes of disorder. RESULTS: Although the majority of those with disorder do not report disability, their difficulties with functioning are far greater than for the rest of the population. Those with comorbid or affective disorders typically have more disability than those with anxiety or substance abuse disorders. CONCLUSIONS: Society needs to recognize the high human and economic costs associated with the prevalence of psychiatric disorder. Assessments of service need and decisions about priorities should take both disorder and disability into consideration.

Adolescent↗

PubMed1995

Identification of polymorphism at the glutathione S-transferase, GSTM3 locus: evidence for linkage with GSTM1*A.

Allelism in the glutathione S-transferase, GSTM3 gene has been identified using PCR with specific primers to exon 6/exon 7. Sequencing showed the mutant GSTM3*B allele to have a three-base deletion in intron 6 with a frequency of 0.158. The mutation generates a recognition sequence, 5'-AAGATA-3', for the negative transcription factor YY1. GSTM3*B was significantly associated with GSTM1*A.

Base Sequence↗

PubMed1995

Electron transport regulates exchange of two forms of photosystem II D1 protein in the cyanobacterium Synechococcus.

Synechococcus sp. PCC 7942 modulates photosynthetic function by transiently replacing the constitutive D1 photosystem II protein, D1:1, with an alternate form, D1:2, to help counteract photoinhibition under excess light. We show that a temperature drop from 37 to 25 degrees C also drives D1:1/D1:2 exchange under constant, moderate light. Chilling or light-induced D1 exchange results from rapid loss of psbAI message coding for D1:1 and accumulation of psbAII and psbAIII messages coding for D1:2. During chilling, a large pool of a novel form, D1:2*, transiently accumulates, distinguishable from normal D1 by an increase in apparent molecular mass. D1:2* is not phosphorylated and is probably a functionally inactive, incompletely processed precursor. After acclimation to 25 degrees C, D1:2* disappears and D1:1 again predominates, although substantial D1:2 remains. Partial inhibition of electron transport under constant, moderate light also triggers the D1 exchange process. These treatments all increase excitation pressure on photosystem II relative to electron transport. Therefore, information from photosynthetic electron transport regulates D1 exchange without any requirement for a change in light intensity or quality, possibly via a redox sensing mechanism proximal to photosystem II.

Antioxidants↗

PubMed1995

Susceptibility to astrocytoma and meningioma: influence of allelism at glutathione S-transferase (GSTT1 and GSTM1) and cytochrome P-450 (CYP2D6) loci.

We describe a case-control study to identify associations between polymorphism at the cytochrome P-450 (CYP2D6) and glutathione S-transferase (GSTT1 and GSTM1) loci and susceptibility to astrocytoma and meningioma. Accordingly, genotype frequencies in 112 astrocytoma and 50 meningioma patients were compared with frequencies in 577 controls. GSTM1 genotype frequencies in these groups were not different. Logistic regression analysis showed GSTT1 null and CYP2D6 poor metabolizer were risk factors in astrocytoma (odds ratio = 2.67 P = 0.0005 and odds ratio = 4.17 P = 0.0043, respectively) and meningioma (odds ratio = 4.52, P = 0.0001 and odds ratio = 4.90, P = 0.0132, respectively) when corrected for the other variables. No interactive effects between genotypes were identified. The data suggest polymorphism at loci encoding carcinogen-metabolizing enzymes influences susceptibility to astrocytoma and meningioma, possibly by determining effectiveness in the detoxification of environmental carcinogens.

Adult↗