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Biomedical subjects

Chris O'Callaghan

Publications and source records attributed to Chris O'Callaghan.

10 recordsLinked to original sources
PubMed2006

Ciliary function and the role of cilia in clearance.

The lungs and the nasal passages are continually exposed to respiratory pathogens, toxins, and particulate matter, and have evolved a very effective defense system to protect themselves. Mucociliary clearance is an essential part of this defence and relies on appropriate interactions between the ciliated epithelium, the height of the periciliary fluid, and mucus. Mucus acts as a physical barrier, trapping inhaled particles and pathogens, whilst cilia move both the mucus layer and fluid in the underlying periciliary layer. These defenses may be disrupted by viral and bacterial infections, by inhaled toxins, and by inherited diseases such as primary ciliary dyskinesia and cystic fibrosis.

Cilia↗
PubMed2006

Has Ontario's Stroke System really made a difference?

The progress that has been made in preventing and treating stroke since 2000, when the Joint Stroke Strategy Working Group tabled its blueprint report, Towards an Integrated Stroke Strategy, is very encouraging. The evaluation results demonstrate that the Ontario Stroke System has had positive measurable impacts on access to stroke-related services, the integration and coordination of stroke care, treatment for stroke, and client and provider satisfaction.

Continuity of Patient Care↗
PubMed2005

Adiponectin and resistin serum levels in women with polycystic ovary syndrome during oral glucose tolerance test: a significant reciprocal correlation between adiponectin and resistin independent of insulin resistance indices.

Polycystic ovary syndrome (PCOS) is associated with an increased incidence of insulin resistance (IR), obesity, and type 2 diabetes. Resistin, an adipocytokine, may represent a link between obesity, and these metabolic disorders. There is also evidence that inflammation is a hyperresistinemic state in humans, and cytokine induction of resistin may contribute to insulin resistance in endotoxemia, obesity, and other inflammatory states. In contrast, adiponectin, increases insulin sensitivity, improves glucose tolerance, inhibits inflammatory pathways, while adenovirus-expressed adiponectin reduces atherosclerotic lesions in a mouse model of atherosclerosis. We aimed to assess, in women with PCOS, whether there is a relationship between adiponectin and resistin and the indices of IR, and whether serum levels of these adipocytokines are altered by glucose-induced hyperinsulinaemia. Serum levels of resistin and adiponectin were measured at 0, 60, and 120 min during 75 g oral glucose tolerance test (OGTT), in 19 women with PCOS, age 36.3+/-11.4 years (mean+/-SD), body mass index (BMI) 29.3+/-7.7 kg/m2, and correlated with the indices of IR, such as HOMA-IR, QUICKI, and the insulin resistance index calculated from glucose and insulin levels obtained during OGTT. There was no change in resistin concentrations (7.31+/-4.58, 7.47+/-5.40, 7.22+/-5.12 pg/ml, at 0, 60, and 120 min of OGTT, respectively, P = 0.77), but there was an increase in adiponectin from 11.32+/-4.64 microg/ml at baseline to 14.78+/-7.41 microg/ml, at 120 min of OGTT (P < 0.01). The magnitude of the overall rise in adiponectin was greater from 60 to 120 min (from 12.31+/-5.72 to 14.78+/-7.41 microg/ml, P < 0.006). Neither resistin, nor adiponectin correlated with the indices of IR, lipids, or other hormonal parameters of the PCOS. There was, however, a significant negative correlation between serum resistin and adiponectin (P = 0.001). In conclusion, we observed a strong negative correlation between serum adiponectin and resistin, despite the lack of direct correlation with the indices of IR. Given the opposite effects of resistin and adiponectin on the inflammatory process, we speculate that relative proportion of adiponectin-to-resistin might potentially influence cardiometabolic risk in women with the PCOS independently of IR parameters. The observed increase in adiponectin during OGTT requires further study.

Adiponectin↗
PubMed2004

Optimizing discharge planning: clinical predictors of longer stay after recombinant tissue plasminogen activator for acute stroke.

BACKGROUND AND PURPOSE: The length of stay (LOS) is the main cost-determining factor for inpatients with acute stroke. Although studies have identified variables associated with LOS, few have analyzed predictors of longer stay after receiving thrombolytic therapy for acute stroke. METHODS: We studied all consecutive acute stroke patients receiving intravenous recombinant tissue plasminogen activator (rtPA) admitted to the London Health Sciences Center, in London, Ontario, Canada, from 1999 to 2003. Longer stay was defined as LOS > or =7 days after admission. Demographic as well as baseline clinical, laboratory, and imaging variables were analyzed to identify predictors of LOS. Significant variables were entered into a multivariate logistic regression analysis. RESULTS: Among 216 acute stroke patients receiving rtPA, the median LOS was 6 days. LOS was >7 days in 102 (49%) patients. Age > or =70 (odds ratio [OR], 2.2; 95% CI, 1.2 to 4.0), lack of improvement at 24 hours (OR, 2.5; 95% CI, 1.4 to 4.4), prestroke modified Rankin Scale > or =2 (OR, 2.4; 95% CI, 1.2 to 4.9), baseline National Institutes of Health Stroke Scale score > or =15 (OR, 9.4; 95% CI, 3.2 to 27.6), cortical involvement (OR, 2.2; 95% CI, 1.2 to 3.9), and new infarction on the control computed tomography (CT; OR, 2.8; 95% CI, 1.4 to 5.9) were independent predictors of longer stay. CONCLUSIONS: Lack of improvement at 24 hours after rtPA, cortical involvement, and new infarction on the 24-hour CT scan are relevant variables that can independently affect the LOS. These new variables may be useful for establishing policy in relation to the organization and planning of the health care system.

Acute Disease↗
PubMed2004

Central microtubular agenesis causing primary ciliary dyskinesia.

Primary ciliary dyskinesia is an autosomal recessive disorder characterized by chronic upper and lower respiratory tract symptoms. We report the diagnosis of primary ciliary dyskinesia associated with a circular ciliary beat pattern in three siblings. This beat pattern is consistent with a ciliary transposition defect, where a peripheral microtubule doublet is transposed to the center of the ciliary axoneme to replace the absent central microtubule pair. However, in these siblings, ultrastructural analysis of the cilia revealed an absence of the central microtubule pair only. This variant of transposition with a circular ciliary beat pattern has not been described previously. In addition, this defect, together with the transposition defect, may help explain the mechanism of the circular beat pattern and also the absence of situs inversus in these patients.

Arabs↗
PubMed2002

Salbutamol dry powder inhaler: efficacy, tolerability, and acceptability study.

Dry powder inhaler (DPI) devices are frequently used in children over 5 years of age in order to avoid coordination difficulties often seen with the use of pressurized metered dose inhalers (pMDI). This study assessed the efficacy, tolerability, and acceptability of salbutamol delivered via two delivery systems, in a population of pediatric patients. The primary aim of the study was to investigate the bronchodilator efficacy of a single dose (100 microg) of salbutamol administered via a dry powder inhaler (Clickhaler) compared to a similar dose administered by a pressurized metered dose inhaler via a large-valved holding chamber (VHC) to children with asthma. The study comprised two phases: the first comparator phase, followed by an open 4-week treatment period. Sixty-one children with a mean (SD) age of 11.3 years (2.9) (range, 6-17) and mild or moderate asthma completed the study. The primary efficacy endpoint, forced expiratory volume in 1 sec (FEV1), indicated that there was no clinically or statistically significant difference between the bronchodilator effects of salbutamol delivered via either device, with a maximum posttreatment percentage change in FEV1 (SD) of 12.4% (10.0) and 14.15 (9.3) for Clickhaler and pMDI plus VHC, respectively. Most patients rated the Clickhaler as easy to use (97%) and liked the device (84%). Both treatments were well--tolerated. These results support the suitability of salbutamol Clickhaler as an acceptable, well-tolerated, and effective alternative to a pMDI plus VHC in mild to moderate asthmatic children over age 6 years.

Administration, Inhalation↗
PubMed2002

Exercise decreases plasma total homocysteine in overweight young women with polycystic ovary syndrome.

Women with polycystic ovary syndrome (PCOS) have a clustering of cardiovascular risk factors, such as obesity, lipid abnormalities, impaired glucose tolerance, insulin resistance, and hypertension. Exercise is reported to lower the incidence of cardiac events. The effect of exercise on plasma homocysteine concentrations, an independent cardiovascular risk factor, has not been previously reported in women with PCOS. We examined the effects of exercise on plasma total homocysteine concentrations in young overweight or obese PCOS women [age (mean +/- SD), 30.6 +/- 6.6 yr; body mass index, 35.49 +/- 7.57 kg/m(2)]. Twenty-one women consented to a 6-month exercise program; 12 women (exercisers) adhered to the program, whereas 9 (nonexercisers) did not. In both groups of women, the following parameters were recorded at baseline and 6 months: body mass index, waist-to-hip ratio, and aerobic capacity (maximal oxygen consumption); blood samples were taken after an overnight fast for plasma total homocysteine, insulin, and other biochemical parameters. A significant decrease in plasma total homocysteine concentrations (P < 0.001) and waist-to-hip ratio (P = 0.041) and a significant increase in maximal oxygen consumption (P = 0.019) were recorded at 6 months, compared with baseline in the exercise group. This decrease in homocysteine was not explained by changes in anthropometric or biochemical parameters. In contrast, no significant changes in any of the variables were observed in the nonexercise group. Our study has provided the first evidence that regular exercise significantly lowers plasma homocysteine in young overweight or obese women with PCOS, a group at increased risk of premature atherosclerosis. The precise mechanism by which exercise is associated with a reduction in homocysteine remains to be elucidated.

Adult↗
PubMed2002

The output of flunisolide from different nebulisers.

The objective of this study was to determine the output, in-vitro, solution of a concentrated solution of flunisolide from two different nebulisers under simulated breathing conditions. The BimboNeb and Nebula nebulisers were used to nebulise 2.6 mL of flunisolide solution (600 microg). Particle size was determined by inertial impaction and the total output of drug from the nebulisers under simulated breathing conditions was measured using a sinus flow pump. Two different breathing patterns were used, simulating nebuliser use by a child and an adult. The mass median aerodynamic diameter of flunisolide particles from the BimboNeb and Nebula were both 3.9 microm. With the simulated paediatric breathing pattern, both nebulisers delivered similar amounts of flunisolide (56.4 microg (s.d. 1.4 microg) and 56.1 microg (5 microg) over 5 min from the BimboNeb and Nebula, respectively). With the adult breathing pattern, flunisolide delivery from the BimboNeb was increased to 88.9 microg (3.3 microg), but delivery from the Nebula was only slightly increased to 64.6 microg (1.4 microg). With both nebulisers, little drug was released after 5 min of nebulisation. Both nebulisers delivered 9-15% of the nominal dose of flunisolide to the breathing simulator, a similar percentage to previous studies with budesonide and more than previous studies with beclometasone. Drug delivery from the BimboNeb, but not the Nebula, was affected by the simulated breathing pattern. This study suggests that drug delivery from nebulisers is dependent upon the interaction between the nebuliser, the drug and the patient.

Administration, Inhalation↗
PubMed2002

Management of croup.

Croup, or laryngotracheobronchitis, is a common childhood illness most often caused by viral infections. It is usually a benign, self-limiting disease, but can result in life-threatening upper airway obstruction. Until recently, it was not uncommon for children with severe croup to be admitted to intensive care for intubation. Management used to be limited to supportive measures, including mist therapy. The use of corticosteroids in patients with croup was controversial for many years but has, in the last decade, transformed the management of this disorder. Although corticosteroids do not alter the history of the viral infection, an adequate dose of oral or parenteral dexamethasone or nebulized budesonide has been shown to have a beneficial effect on the symptoms of croup.

Administration, Inhalation↗