ABSTRACT
Background: Concussion is a global public health problem. In Canada, concussion is among the top five reasons for workplace time-loss. Concussion results in physical, cognitive, and/or emotional symptoms that temporarily worsen with physical and mental exertion, such as viewing electronic screens. The Internet is the primary source of consumer health information. Studies on the end-user needs of adults with brain injuries in regards to digital health technologies largely focus on informational content. There is little to no research on the accessibility of screen-based informational websites and smartphone applications among this population. Objective: The aim of this research was to involve stakeholders in the design of a comprehensive educational resource to guide concussion recognition, recovery, and return-to-work, called the Concussion Awareness Training Tool for Workers and Workplaces (CATT WW). In order to ensure both relevant content and appropriate delivery of the information to the target groups, participants were asked whether adaptations could increase the accessibility of online health information for the general adult population experiencing concussion symptoms. Methods: Data have been generated through semi-structured in-depth interviews and focus groups with participants from across British Columbia (BC): workers from various industries who were in the concussion recovery process or had returned to work (n = 31); and healthcare or workplace professionals who support concussion diagnosis, recovery, and return-to-work (n = 16). Data were analyzed using NVivo 12. Before commencing data collection, ethical permission was granted by the University of British Columbia Research Ethics Board (H18-00604), and approval was received from WorkSafeBC Research Services. Results: Participants (n = 47) recommended twenty adaptations or supplements to electronic screen-based digital health technologies. Conclusion: Given the high prevalence of concussion among the working adult population, the symptom exacerbation commonly caused by prolonged use of electronic screens, and the demand for online educational resources, these findings can guide clinicians, researchers, technology developers, employers, and occupational health and safety committees to further support adults in concussion recovery and return-to-work.
Subject(s)
Brain Concussion , Adult , Brain Concussion/diagnosis , British Columbia , Delivery of Health Care , Humans , Return to Work , WorkplaceABSTRACT
BACKGROUND: The British Columbia Coroners Service implemented a policy in 2010 advising the reclassification of underlying causes of deaths due to falls from 'natural' to 'accidental'. This study investigates whether observed data trends reflect this change in practice, are artefacts of inconsistent reporting, or indicate a true increase in fall-related deaths. METHODS: Mortality data were analysed from 2004 to 2017 for cases with International Statistical Classification of Diseases and Related Health Problems, 10th Revision fall codes W00-W19, occurring among adults aged 60 years and older. RESULTS: From 2010 to 2012, accidental fall-related deaths increased among those aged 80 years and older, followed by an increase in natural deaths with fall as the contributing cause. CONCLUSIONS: Changes in reporting resulting from the 2010 policy change were observed; however, post-2012 data indicate a reversion to previous reporting practices.
Subject(s)
Accidental Falls , Policy , Aged , British Columbia , Humans , Middle AgedSubject(s)
Inflammatory Bowel Diseases , Pancreatitis , Azathioprine , Genotype , Humans , PhenotypeABSTRACT
BACKGROUND: Azathioprine (AZA)-induced pancreatitis is an unpredictable and dose-independent adverse event affecting 2%-7% of patients with inflammatory bowel disease (IBD) patients treated with AZA. There are no tools in clinical practice to identify at-risk individuals; however, a genome wide association study (GWAS) identified a strong association between the Class II HLA gene region polymorphism (rs2647087) and thiopurine-induced pancreatitis. AIM: To independently confirm the findings of the GWAS in an IBD cohort, to evaluate its utility in clinical practice and to offer a novel AZA treatment algorithm for IBD based on pharmacogenomic principles. METHODS: A retrospective cohort study evaluated 373 AZA-exposed IBD patients from a tertiary care academic centre in London, Canada. Due to the limited number of patients taking mercaptopurine (MP), such patients were not included this cohort. All subjects underwent screening for the single nucleotide polymorphism (SNP) rs2647087 mapped to the HLA-DQA1*02:01-HLA-DRB1*07:01 haplotype and were sub-divided based on the presence (n = 13) or absence (n = 360) of an AZA-induced pancreatitis diagnosis. The risk of AZA-induced pancreatitis was assessed based on rs2647087 genotype. RESULTS: The risk of pancreatitis during AZA-therapy was highly predictable and genotype dependent: 0.53% for wild type (A/A), 4.25% (OR = 4.19, 95% CI 1.02-36.45, P = 0.044) for heterozygous (A/C), and 14.63% (OR = 15.83, 95% CI 3.80-145.26, P = 0.0001) for homozygous variant (C/C) patients. CONCLUSIONS: The class II HLA region (at rs2647087) is an important marker of AZA-induced pancreatitis risk. We propose a simple and clinically implementable algorithm based on rs2647087 and TPMT genotypes for AZA selection and dosing for patients with IBD.
Subject(s)
Azathioprine/adverse effects , HLA-DQ alpha-Chains/genetics , HLA-DRB1 Chains/genetics , Inflammatory Bowel Diseases/drug therapy , Inflammatory Bowel Diseases/genetics , Pancreatitis/chemically induced , Pancreatitis/genetics , Adult , Azathioprine/therapeutic use , Canada , Case-Control Studies , Cohort Studies , Female , Genome-Wide Association Study , Genotype , Haplotypes , Humans , Male , Middle Aged , Pharmacogenetics , Polymorphism, Single Nucleotide , Retrospective StudiesABSTRACT
BACKGROUND: Elevated iron indices are described in non-alcoholic fatty liver disease and iron reduction has been suggested as a potential therapy. AIM: To determine whether phlebotomy is an effective therapy for non-alcoholic fatty liver disease. METHODS: Patients with biopsy proven non-alcoholic fatty liver disease underwent baseline evaluation to determine severity of metabolic and liver disease. A Phase II trial of phlebotomy was carried out to achieve near-iron depletion (serum ferritin ≤50 µg/L or haemoglobin 100 g/L). Repeat liver biopsy, anthropometric and biochemical measurements were performed 6 months following the end of treatment. Primary outcome was improvement in liver histology, assessed using the non-alcoholic fatty liver disease activity score. RESULTS: Thirty-one patients completed follow-up. Iron reduction resulted in a significant improvement in the non-alcoholic fatty liver disease activity score (-0.74 ± 1.83, P = 0.019). Reductions in individual histological features of lobular inflammation (-0.29 ± 1.07, P = 0.182), steatosis (-0.26 ± 0.82, P = 0.134), hepatocyte ballooning (-0.19 ± 0.70, P = 0.213) did not achieve significance nor did the score for fibrosis (-0.32 ± 0.94, P = 0.099). CONCLUSIONS: This prospective Phase II study of phlebotomy with paired liver biopsies evaluating phlebotomy therapy in non-alcoholic fatty liver disease patients suggests that iron reduction may improve liver histology. However, the effect size of phlebotomy raises questions of whether treatment could have sufficient clinical significance to justify a definitive Phase III trial. This trial has been registered with the US National Institute of Health (clinicaltrials.gov, Identifier NCT 00641524).
Subject(s)
Fatty Liver/therapy , Phlebotomy/methods , Adult , Fatty Liver/blood , Female , Ferritins/blood , Humans , Liver/metabolism , Male , Middle Aged , Non-alcoholic Fatty Liver DiseaseABSTRACT
In closed environments, the concentration of carbon monoxide (CO) can easily rise to health-threatening levels. CO-related incidents are often caused by poor condition or inappropriate use of indoor combustion devices as well as structure fires but are also due to suicides. To evaluate the incidence of CO poisoning in Europe, national data on CO-related mortality and morbidity were compiled from Member States of the WHO European Region using a standardized data collection form. National data on CO poisoning were provided by 28 Member States. Within the maximum reporting period (1980-2008), a total of 140 490 CO-related deaths were reported (annual death rate of 2.2/100 000). The number of hospital admissions available from six countries was 31 473. Unintentional CO deaths accounted for 54.7% of the CO-related deaths (35.9%: unintentional inhalation; 18.8%: related to structure fires). The intentional deaths related to CO exposure account for 38.6% of all CO-related deaths (38.1%: suicides; 0.5%: homicides). CO exposure is preventable but causes a substantial amount of deaths in many European countries. More efficient measures and policies to prevent CO poisoning and better reporting of CO mortality are necessary.
Subject(s)
Carbon Monoxide Poisoning/mortality , Adolescent , Adult , Aged , Carbon Monoxide Poisoning/prevention & control , Child , Child, Preschool , Europe/epidemiology , Female , Health Literacy , Hospitalization/statistics & numerical data , Humans , Infant , Male , Middle Aged , World Health Organization , Young AdultABSTRACT
BACKGROUND: Vasoactive medications such as vasopressin, somatostatin and their analogues (terlipressin, vapreotide and octreotide) are commonly used for the treatment of acute variceal bleeding. However, the risks and benefits of these interventions are not well understood. AIM: To undertake a meta-analysis of the efficacy of vasoactive medications in patients having acute variceal bleeds. METHODS: Randomised controlled trials (RCTs) of vasopressin, somatostatin and their analogues, administered to patients with acute variceal bleeds were identified based on systematic searches of nine electronic databases and multiple sources of grey literature. RESULTS: The search identified 3011 citations, and 30 trials with a total of 3111 patients met eligibility criteria. The use of vasoactive agents was associated with a significantly lower risk of 7-day mortality (RR 0.74; 95% CI 0.57-0.95; P = 0.02; I(2) = 0%; moderate quality of evidence), and a significant improvement in haemostasis (RR 1.21, 95% CI 1.13-1.30; P < 0.001; I(2) = 28%; very low quality of evidence), lower transfusion requirements (pooled mean difference -0.70 units of blood transfused, 95% CI -1.01 to -0.38; P < 0.001; I(2) = 82%; moderate quality of evidence), and a shorter duration of hospitalisation (pooled mean difference -0.71 days; 95% CI -1.23 to -0.19; P = 0.007; I(2) = 0%; low quality of evidence). Studies comparing different vasoactive agents did not show a difference in efficacy, although the quality of evidence was very low. CONCLUSIONS: The use of vasoactive agents was associated with a significantly lower risk of acute all-cause mortality and transfusion requirements, and improved control of bleeding and shorter hospital stay. Studies comparing different vasoactive medications failed to demonstrate a difference in efficacy.
Subject(s)
Esophageal and Gastric Varices/drug therapy , Gastrointestinal Hemorrhage/drug therapy , Hemostatics/therapeutic use , Somatostatin/therapeutic use , Vasopressins/therapeutic use , Humans , Lypressin/analogs & derivatives , Lypressin/therapeutic use , Octreotide/therapeutic use , Randomized Controlled Trials as Topic , Somatostatin/analogs & derivatives , TerlipressinABSTRACT
Chromophyte algae differ fundamentally from plants in possessing chloroplasts that contain chlorophyll c and that have a more complex bounding-membrane topology. Although chromophytes are known to be evolutionary chimaeras of a red alga and a non-photosynthetic host, which gave rise to their exceptional membrane complexity, their cell biology is poorly understood. Cryptomonads are the only chromophytes that still retain the enslaved red algal nucleus as a minute nucleomorph. Here we report complete sequences for all three nucleomorph chromosomes from the cryptomonad Guillardia theta. This tiny 551-kilobase eukaryotic genome is the most gene-dense known, with only 17 diminutive spliceosomal introns and 44 overlapping genes. Marked evolutionary compaction hundreds of millions of years ago eliminated nearly all the nucleomorph genes for metabolic functions, but left 30 for chloroplast-located proteins. To allow expression of these proteins, nucleomorphs retain hundreds of genetic-housekeeping genes. Nucleomorph DNA replication and periplastid protein synthesis require the import of many nuclear gene products across endoplasmic reticulum and periplastid membranes. The chromosomes have centromeres, but possibly only one loop domain, offering a means for studying eukaryotic chromosome replication, segregation and evolution.
Subject(s)
Eukaryota/genetics , Genome , Base Sequence , Cell Nucleus , Chloroplasts/genetics , Chromosome Mapping , Cyanobacteria/genetics , Molecular Sequence Data , Rhodophyta/genetics , Sequence Analysis, DNA , SymbiosisSubject(s)
Hospitals, Animal , Animal Welfare , Animals , Food/standards , Hospitals, Animal/economics , Humans , Population Surveillance , Public Health , ScotlandSubject(s)
Arthritis, Psoriatic/genetics , Family , Medical Records/standards , Self Disclosure , Adult , Humans , Middle AgedABSTRACT
OBJECTIVE: To compare patients with familial versus sporadic psoriatic arthritis (PsA) with respect to clinical, radiological and immunogenetic features. METHODS: All patients were identified from the University of Toronto Psoriatic Arthritis Clinic. Familial and sporadic PsA were distinguished based on the proband's self-reported history. The probands were compared at presentation to clinic with respect to: demographic information, age of onset of psoriasis and inflammatory arthritis, disease activity, disease damage, laboratory variables, functional class and HLA antigens. The two groups were compared using a univariate analysis. RESULTS: In total 407 patients were included. Thirty-six patients (8.8%) were eliminated as they reported a family history of arthritis in the absence of psoriasis. Of the remaining 371 patients, 150 patients reported a positive family of either PsA or psoriasis. 221 patients (54.2%) had no family history of psoriatic arthritis, psoriasis, or "arthritis". The familial group were younger at presentation to clinic (p = 0.003), had an earlier age of onset of psoriasis (p = 0.001) and inflammatory arthritis (p = 0.001) and were more likely to be receiving treatment (p = 0.001). The mean number of actively inflamed joints was higher in the sporadic group (p = 0.035), along with a higher frequency of rheumatoid factor positivity (p = 0.04). Only the age of onset variables and medication use retained significance after correction for multiple comparisons. CONCLUSIONS: In comparing probands with familial versus sporadic PsA, we noted a marked difference in the age of onset of psoriasis and inflammatory arthritis, along with other differences in several clinical variables. These differences may be helpful in identifying PsA patients with a stronger genetic predisposition.
Subject(s)
Arthritis, Psoriatic/genetics , Arthritis, Psoriatic/immunology , Adult , Age of Onset , Antirheumatic Agents/therapeutic use , Arthritis, Psoriatic/diagnostic imaging , Arthritis, Psoriatic/physiopathology , Female , HLA Antigens/analysis , Humans , Male , Medical Records , Middle Aged , Radiography , Rheumatoid Factor/blood , Severity of Illness IndexABSTRACT
Cells of several major algal groups are evolutionary chimeras of two radically different eukaryotic cells. Most of these "cells within cells" lost the nucleus of the former algal endosymbiont. But after hundreds of millions of years cryptomonads still retain the nucleus of their former red algal endosymbiont as a tiny relict organelle, the nucleomorph, which has three minute linear chromosomes, but their function and the nature of their ends have been unclear. We report extensive cryptomonad nucleomorph sequences (68.5 kb), from one end of each of the three chromosomes of Guillardia theta. Telomeres of the nucleomorph chromosomes differ dramatically from those of other eukaryotes, being repeats of the 23-mer sequence (AG)(7)AAG(6)A, not a typical hexamer (commonly TTAGGG). The subterminal regions comprising the rRNA cistrons and one protein-coding gene are exactly repeated at all three chromosome ends. Gene density (one per 0.8 kb) is the highest for any cellular genome. None of the 38 protein-coding genes has spliceosomal introns, in marked contrast to the chlorarachniophyte nucleomorph. Most identified nucleomorph genes are for gene expression or protein degradation; histone, tubulin, and putatively centrosomal ranbpm genes are probably important for chromosome segregation. No genes for primary or secondary metabolism have been found. Two of the three tRNA genes have introns, one in a hitherto undescribed location. Intergenic regions are exceptionally short; three genes transcribed by two different RNA polymerases overlap their neighbors. The reported sequences encode two essential chloroplast proteins, FtsZ and rubredoxin, thus explaining why cryptomonad nucleomorphs persist.
Subject(s)
Centrosome , Chimera/genetics , Eukaryota/genetics , Introns/genetics , RNA, Transfer/genetics , Telomere/genetics , Algal Proteins/genetics , Base Sequence , Biological Evolution , Cloning, Molecular , Genes, Plant/genetics , Genome , Molecular Sequence Data , Nucleic Acid Conformation , Physical Chromosome Mapping , Repetitive Sequences, Nucleic AcidABSTRACT
Inositol monophosphatase plays a pivotal role in the biosynthesis of secondary messengers and is believed to be a target for lithium therapy. It is established how a lithium ion works in inhibiting the enzyme but details of the mechanism for the direct magnesium ion activated hydrolysis of the substrate have been elusive. It is known that substrates require a minimal 1,2-diol phosphate structural motif, which in D-myo-inositol 1-phosphate relates to the fragment comprising the 1-phosphate ester and the 6-hydroxy group. Here it is shown that inhibitors that are D-myo-inositol 1-phosphate substrate analogues possessing 6-substituents larger than the 6-hydroxy group of the substrate, for example, the 6-O-methyl analogue, are able to bind to the enzyme in a congruous manner to the substrate. It is demonstrated, however, that such compounds show no substrate activity whatsoever. It is also shown that a 6-amino group is able to fulfil the role of the 6-hydroxy group of the substrate in conferring substrate activity and that a 6-methylamino group is similarly able to support catalysis. The results indicate that a 6-substituent capable of serving as a hydrogen-bond donor is required in the catalytic mechanism for hydrolysis. It has recently been shown that inositol is displaced from phosphorus with inversion of stereochemistry and we expect that the nucleophilic species is associated with Mg(2+)-1. It is proposed here that the role of the 6-hydroxy group of the substrate is to H-bond with a water molecule or hydroxide ion located on Mg(2+)-2. From this analysis, it appears that the water molecule bound to Mg(2+)-2 serves as a proton donor for the inositolate leaving group in a process that stabilises the alkoxide product and retards the back-reaction.
Subject(s)
Inositol Phosphates/chemistry , Magnesium/chemistry , Phosphoric Monoester Hydrolases/chemistry , Animals , Binding Sites , Binding, Competitive , Catalytic Domain , Cattle , Hydrogen Bonding , Hydrolysis , Inositol Phosphates/metabolism , Inositol Phosphates/pharmacology , Models, Chemical , Models, Molecular , Protein Conformation , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Stereoisomerism , Substrate Specificity , Water/chemistryABSTRACT
Genic DNA functions are commonplace: coding for proteins and specifying non-messenger RNA structure. Yet most DNA in the biosphere is non-genic, existing in nuclei as non-coding or secondary DNA. Why so much secondary DNA exists and why its amount per genome varies over orders of magnitude (correlating positively with cell volume) are central biological problems. A novel perspective on secondary DNA function comes from natural eukaryote eukaryote chimaeras (cryptomonads and chlorarachneans) where two phylogenetically distinct nuclei have coevolved within one cell for hundreds of millions of years. By comparing cryptomonad species differing 13-fold in cell volume, we show that nuclear and nucleomorph genome sizes obey fundamentally different scaling laws. Following a more than 125-fold reduction in DNA content, nucleomorph genomes exhibit little variation in size. Furthermore, the present lack of significant amounts of nucleomorph secondary DNA confirms that selection can readily eliminate functionless nuclear DNA, refuting 'selfish' and 'junk' theories of secondary DNA. Cryptomonad nuclear DNA content varied 12-fold: as in other eukaryotes, larger cells have extra DNA, which is almost certainly secondary DNA positively selected for a volume-related function. The skeletal DNA theory explains why nuclear genome size increases with cell volume and, using new evidence on nucleomorph gene functions, why nucleomorph genomes do not.
Subject(s)
DNA/genetics , Eukaryotic Cells , Genome , Animals , Sequence Analysis, DNAABSTRACT
DNA can be divided functionally into three categories: (1) genes--which code for proteins or specify non-messenger RNAs; (2) semons--short specific sequences involved in the replication, segregation, recombination or specific attachments of chromosomes, or chromosome regions (e.g. loops or domains) or selfish genetic elements; (3) secondary DNA--which does not function by means of specific sequences. Probably more than 90% of DNA in the biosphere is secondary DNA present in the nuclei of plants and phytoplankton. The amount of genic DNA is related to the complexity of the organism, whereas the amount of secondary DNA increases proportionally with cell volume, and not with complexity. This correlation is most simply explained by the skeletal DNA hypothesis, according to which nuclear DNA functions as the basic framework for the assembly of the nucleus and the total genomic DNA content functions (together with relatively invariant folding rules) in determining nuclear volumes. Balanced growth during the cell cycle requires the cytonuclear ratio to be basically constant, irrespective of cell volume; thus nuclear volumes, and therefore the overall genome size, have to be evolutionarily adjusted to changing cell volumes for optimal function. Bacteria, mitochondria, chloroplasts and viruses have no nuclear envelope; and the skeletal DNA hypothesis simply explains why secondary DNA is essentially absent from them but present in large cell nuclei. Hitherto it has been difficult to refute the alternative hypothesis that nuclear secondary DNA (whether 'junk' or selfish DNA) accumulates merely by mutation pressure, and that selection for economy is not strong enough to eliminate it, whereas accumulation in mitochondria and plastids is prevented by intracellular replicative competition between their multiple genomes. New data that discriminate clearly between these explanations for secondary DNA come from cryptomonads and chlorarachneans, two groups of algae that originated independently by secondary symbiogenesis (i.e., the merger of two radically different eukaryote cells) several hundred million years ago. In both groups the nucleus and plasma membrane of the former algal symbiont persist as the nucleomorphs and periplastid membrane, respectively. The fact that nucleomorphs have undergone a 200- to 1000-fold reduction in genome size and have virtually no secondary DNA shows that selection against non-functional nuclear DNA is strong enough to eliminate it very efficiently; therefore, the large amounts of secondary DNA in the former host nuclei of these chimaeras, and in nuclei generally, must be being maintained by positive selection. The divergent selection for secondary DNA in the nucleus and against it in nucleomorphs is readily explicable by the skeletal DNA hypothesis, given the different spectrum of gene functions that it encodes.
Subject(s)
Cell Nucleus/genetics , DNA/genetics , Eukaryota/genetics , Eukaryotic Cells , Evolution, Molecular , Genome , DNA, Bacterial/genetics , DNA, Chloroplast/genetics , DNA, Mitochondrial/genetics , DNA, Viral/genetics , SymbiosisABSTRACT
The nucleotide sequence for an 11,715-bp segment of the mitochondrial genome of the octocoral Sarcophyton glaucum is presented, completing the analysis of the entire genome for this anthozoan member of the phylum Cnidaria. The genome contained the same 13 protein-coding and 2 ribosomal RNA genes as in other animals. However, it also included an unusual mismatch repair gene homologue reported previously and codes for only a single tRNA gene. Intermediate in length compared to two other cnidarians (17,443 and 18,911 bp), this organellar genome contained the smallest amount of noncoding DNA (428, compared to 1283 and 781 nt, respectively), making it the most compact one found for the phylum to date. The mitochondrial genes of S. glaucum exhibited an identical arrangement to that found in another octocoral, Renilla kolikeri, with five protein-coding genes in the same order as has been found in insect and vertebrate mitochondrial genomes. Although gene order appears to be highly conserved among octocorals, compared to the hexacoral, Metridium senile, few similarities were found. Like other metazoan mitochondrial genomes, the A + T composition was elevated and a general bias against codons ending in G or C was observed. However, an exception to this was the infrequent use of TGA compared to TGG to code for tryptophan. This divergent codon bias is unusual but appears to be a conserved feature among two rather distantly related anthozoans.
Subject(s)
Cnidaria/genetics , DNA, Mitochondrial/genetics , Amino Acid Sequence , Animals , Base Composition , Base Sequence , Chromosome Mapping , Codon, Initiator/genetics , Codon, Terminator/genetics , Conserved Sequence , DNA, Mitochondrial/chemistry , Evolution, Molecular , Genome , Molecular Sequence Data , Proteins/genetics , RNA, Ribosomal/genetics , Sequence Homology, Nucleic Acid , Species SpecificityABSTRACT
We used a modified rebreathing technique to measure chemoreflex thresholds to CO2 in decerebrate, paralyzed and ventilated cats. Cats were hyperventilated to neural apnea (PaCO2 < 15 mmHg) with one ventilator and then switched to a rebreathing circuit consisting of a balloon inside a bottle connected to a second ventilator. The volume of the circuit was approximately 110 ml. The balloon contained 5% CO2:95% O2 for hyperoxic rebreathing or approximately 5% CO2 with 11 or 6.5% O2 for moderately and severely hypoxic rebreathing. A plateau in CO2 concentration at the onset of rebreathing indicated equilibration of CO2 between the circuit, alveolar gas and venous and arterial blood. After rapid equilibration of CO2 between the cat and the circuit, CO2 increased linearly with time during rebreathing. Under hyperoxic conditions, phrenic activity began to increase at an end-tidal P(CO2) (PET(CO2)) of 35.1 +/- 6.1 (SD) mmHg (n = 8); during hypoxia, phrenic activity began to increase at a significantly lower PET(CO2) of 27.8 +/- 4.8 mmHg (P < 0.01, n = 6). We interpret these values as the central and peripheral chemoreflex thresholds to CO2, respectively. Persistent phrenic activity prevented determination of a threshold during severe hypoxic rebreathing. Our modified method of hyperoxic and hypoxic rebreathing allows detection of the effects of hypoxia on the central and peripheral chemoreflex thresholds and, within a cat, measurements of chemoreflex sensitivities.
Subject(s)
Carbon Dioxide/pharmacology , Chemoreceptor Cells/drug effects , Decerebrate State/physiopathology , Reflex/drug effects , Animals , Cats , Differential Threshold/physiology , Female , Hyperoxia/physiopathology , Hypoxia/physiopathology , Male , Partial Pressure , Phrenic Nerve/physiopathology , Pulmonary Alveoli/physiopathology , RespirationSubject(s)
Cyclohexanols/chemistry , Enzyme Inhibitors/chemistry , Phosphoric Monoester Hydrolases/metabolism , Animals , Brain/enzymology , Cyclohexanols/chemical synthesis , Cyclohexanols/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Mammals , Models, Molecular , Molecular Conformation , Phosphoric Monoester Hydrolases/antagonists & inhibitors , Substrate SpecificityABSTRACT
Mail surveys have been used to follow-up early participants in a Canadian breast cancer prevention trial. To minimize non-response bias, we undertook a randomized study of two postal strategies, of which one was our usual procedure and the other was a systematic application, known as the total design method (TDM) and described by Dillman. The response rates to the two methods were 62 and 88% respectively. The TDM is a practical, cost-efficient approach to reducing non-response bias in postal surveys and as such has an important role in epidemiological research which involves healthy participants.