Upper airway muscle dysfunction is implicated in obstructive sleep apnoea syndrome (OSAS), a common respiratory disorder associated with recurrent hypoxaemia. The prevalence of OSAS is higher in males than females. We tested the hypothesis that sex differences exist in the effects of intermittent hypoxia on upper airway muscle function.
View Article and Find Full Text PDFChronic intermittent hypoxia (CIH), a feature of obstructive sleep apnoea (OSA) has been shown to have myriad effects on the respiratory control system. The effects on breathing are of great clinical significance for the sleep apnoea patient. We sought to determine the effect of CIH on normoxic ventilation.
View Article and Find Full Text PDFLitters of rats were exposed to normobaric normoxia or hypobaric hypoxia (P(B)= 450 mmHg) for 7 days at 3 different time points during early development (postnatal day (P)1, P6 & P11). A separate litter exposed to hypoxia at P11 was treated with the antioxidant Tempol (100 mg/kg) given by oral administration daily starting at P8. At P19, sternohyoid and diaphragm muscles were removed and isolated muscle bundles were mounted isometrically in physiological salt solution at 30 degrees C in vitro.
View Article and Find Full Text PDFVagal paraganglia resemble the carotid body and are chemosensitive to reduction in the partial pressure of oxygen (P O2) (O'Leary et al., 2004). We hypothesised that they may also mediate communication between the immune system and the central nervous system and more specifically respond to the pro-inflammatory cytokines: interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha).
View Article and Find Full Text PDFVet Immunol Immunopathol
March 2010
A fraction of cats exposed to feline leukemia virus (FeLV) effectively contain virus and resist persistent antigenemia/viremia. Using real-time PCR (qPCR) to quantitate circulating viral DNA levels, previously we detected persistent FeLV DNA in blood cells of non-antigenemic cats considered to have resisted FeLV challenge. In addition, previously we used RNA qPCR to quantitate circulating viral RNA levels and determined that the vast majority of viral DNA is transcriptionally active, even in the absence of antigenemia.
View Article and Find Full Text PDFDendritic cells (DC) are potent antigen presenting cells which initiate and coordinate the immune response making them central targets of and attractive candidates for manipulation in chronic lentiviral infections. Emerging evidence suggests that DC immune function is disrupted during both acute and chronic infection with human immunodeficiency virus (HIV), simian immunodeficiency virus (SIV), and feline immunodeficiency virus (FIV). Despite some early promising data, the use of DC for lentiviral immunotherapy has not fulfilled its expected potential and has been complicated by the large number of variables involved in DC harvesting, purifying, and antigen loading.
View Article and Find Full Text PDFAm J Respir Cell Mol Biol
June 2010
Obstructive sleep apnea is a common disorder associated with upper airway muscle dysfunction. Agents that improve respiratory muscle performance may be useful as an adjunct therapy. The aim of this study was to examine the effects of antioxidants on rat pharyngeal dilator muscle performance.
View Article and Find Full Text PDFObstructive sleep apnoea is characterized by chronic intermittent hypoxia (CIH) due to recurrent apnoea. We have developed a rat model of CIH, which shows evidence of impaired respiratory muscle function. In this study, we wished to characterize the ventilatory effects of CIH in conscious male and female animals.
View Article and Find Full Text PDFMultifunctional multilayer films consisting of the Keggin-type polyoxometalate [SiW(9)V(3)O(40)](7-) (SiW(9)V(3)) and bismuth oxide nanoparticles (Bi(2)O(3)) were prepared by the layer-by-layer assembly method. For the first time, electrochromic and photochromic studies were done on a film containing both polyoxometalates and nanoparticles. The films were characterized by UV-vis absorption, emission spectra, and atomic force microscopy.
View Article and Find Full Text PDFThis study examined the potential biological hazard of pulp and paper waste solids. The solids examined were chosen on the basis of the range of wood-related organic extractives and were either primary solids screened from the effluent stream before secondary treatment, or biosolids from aerated stabilisation lagoons. Acute effects were tested at the level of plants, invertebrates and soil microbes using an oat germination and growth test, earthworm survival and reproduction test, an enchytraeid worm survival and reproduction test, and standard measures of microbial respiration.
View Article and Find Full Text PDFThe method of analysis for sulfate by reduction of high oxidation state sulfur to hydrogen sulfide, followed by spectrophotometric analysis, has the advantages of allowing small quantities to be measured and some interfering species to be removed. However, it has been found that acid digested samples cannot be analysed by this method due to destruction of the reduction mixture. A column of zirconium(IV) oxide was successfully used to both, remove interfering ions (H(+), Cl(-) and NO(-)(3)) from a sediment digest, as well as perform preconcentration of sulfate.
View Article and Find Full Text PDFImpaired dendritic cell (DC) function is thought to be central to human immunodeficiency virus-associated immunodeficiency. In this study, we examined the effect of chronic feline immunodeficiency virus (FIV) infection on DC cytokine production in response to microbial and T-cell stimulation. Cytokine production after either Toll-like receptor (TLR) or CD40 ligation in bone marrow-derived DCs (BM-DCs) was measured in naïve and chronically FIV-infected cats.
View Article and Find Full Text PDFWe undertook the present investigation to establish whether narrowing/closure of the upper airway occurs during spontaneous and provoked respiratory rhythm disturbances and whether pharyngeal constrictor muscle recruitment occurs coincident with upper airway occlusion during prolonged expiratory periods. Upper airway pressure-flow relationships and middle pharyngeal constrictor (mPC) EMG activities were recorded in 11 adult female goats during spontaneous and provoked prolongations in expiratory time (Te). A total of 213 spontaneous prolongations of expiration were recorded.
View Article and Find Full Text PDFBackground: Hospitalized patients frequently have urinary catheters inserted for inappropriate reasons. This can lead to urinary tract infections and other complications.
Objective: To assess whether stop orders for indwelling urinary catheters reduces the duration of inappropriate urinary catheterization and the incidence of urinary tract infections.
Investigating the toxicity of acid mine drainage (AMD) on benthic communities in receiving waters can be highly challenging because of the difficulty in unraveling the effects of acidity, dissolved metals, and precipitates. Furthermore, the survival of different species may vary depending on any natural adaptation they may have acquired to low pH, metals, or sedimentation. We investigated the effect of different pHs and AMD on the survival of a common New Zealand leptophlebiid mayfly (Deleatidium spp.
View Article and Find Full Text PDFWe previously defined four categories of feline leukemia virus (FeLV) infection, designated as abortive, regressive, latent, and progressive. To determine if detectable viral DNA is transcriptionally active in the absence of antigenemia, we developed and validated a real-time viral RNA qPCR assay. This assay proved to be highly sensitive, specific, reproducible, and allowed reliable quantitation.
View Article and Find Full Text PDFFeline immunodeficiency virus (FIV) interacts with dendritic cells (DC) during initiation of infection, but whether DC support or transfer FIV infection remains unclear. To address this issue, we studied the susceptibility of feline myeloid DC to FIV infection and assessed potential transfer of infection from DC to CD4(+) T cells. FIV was detected in membrane-bound vesicles of DC within 2 h of inoculation, although only low concentrations of FIV DNA were found in virus-exposed isolated DC.
View Article and Find Full Text PDFHeart failure is a clinical syndrome that normally requires health care to be provided by both specialists and nonspecialists. This is advantageous because patients benefit from complementary skill sets and experience, but can present challenges in the development of a common, shared treatment plan. The Canadian Cardiovascular Society published a comprehensive set of recommendations on the diagnosis and management of heart failure in January 2006, and on the prevention, management during intercurrent illness or acute decompensation, and use of biomarkers in January 2007.
View Article and Find Full Text PDFObstructive sleep apnoea is characterised by intermittent hypoxia due to recurrent obstructions of the pharyngeal airway during sleep. We have shown that chronic intermittent hypoxia impairs respiratory muscle function and CNS control of upper airway patency. In this study, we tested the hypothesis that disruption of an endogenous antioxidant defence system exacerbates the effects of intermittent hypoxia on upper airway muscle contractile function.
View Article and Find Full Text PDFAerobic organisms maintain O(2) homeostasis by responding to changes in O(2) supply and demand in both short and long time domains. In this review, we introduce several specific examples of respiratory plasticity induced by chronic changes in O(2) supply (environmental hypoxia or hyperoxia) and demand (exercise-induced and temperature-induced changes in aerobic metabolism). These studies reveal that plasticity occurs throughout the respiratory system, including modifications to the gas exchanger, respiratory pigments, respiratory muscles, and the neural control systems responsible for ventilating the gas exchanger.
View Article and Find Full Text PDFMurray cod (Maccullochella peelii peelii) is an iconic native Australian freshwater fish and an ideal species for ecotoxicological testing of environmental pollutants. The species is indigenous to the Murray-Darling basin, which is the largest river system in Australia but also the ultimate sink for many environmental pollutants. The organotins tributyltin (TBT) and dibutyltin (DBT) are common pollutants of both freshwater and marine environments and are also known for their immunotoxicity in both mammals and aquatic organisms.
View Article and Find Full Text PDFBackground: Monitoring biological responses that are mediated via the aryl-hydrocarbon receptor (AhR) in animals exposed to environmental contaminants can indicate both the presence of chemicals that act through this biochemical pathway and whether these chemicals are bioavailable.
Objectives: The use of an ex-situ method that incorporated biological responsiveness monitoring in mice for determining the presence of 'biologically active' hydrocarbons in contaminated soils was investigated.
Methods: The use of C57BL/6 as a test organism was validated by determining hepatic and immune responsiveness to two polyaromatic hydrocarbons (PAHs): 3,4 benz[a]pyrene (B[a]P) and 1,2 benz (a)anthracene (BA) administered via intraperitoneal (i.
Background: Obstructive sleep apnoea is caused by collapse of the upper airway. The presence of CO(2) in the upper airway lumen evokes a number of reflexes which favour upper airway re-opening, and we have proposed previously that CO(2) would build up in the upper airway following airway collapse and that this would contribute to reflex airway re-opening. However, it is not known if CO(2) can transfer from the alveoli to the anatomical dead space of the upper airway during apnoea.
View Article and Find Full Text PDFHeart failure is common, yet it is difficult to treat. It presents in many different guises and circumstances in which therapy needs to be individualized. The Canadian Cardiovascular Society published a comprehensive set of recommendations in January 2006 on the diagnosis and management of heart failure, and the present update builds on those core recommendations.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
October 2006
The effect of ozone on the formation, breakup and re-formation of flocs generated using ferric sulphate has been investigated using conventional jar test procedure and by continuous optical monitoring using raw water. Using a range of different dosage of coagulant, the breakage of flocs was followed at a high stirring speed, corresponding to average shear rate (G) of about 518 s(-1). Most of the breakage occurred within a few seconds of increasing the shear rate.
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