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Biomedical subjects

C Person

Publications and source records attributed to C Person.

At least 19 recordsLinked to original sources
PubMed2005

[Long term use of nCPAP therapy in sleep apnoea patients].

INTRODUCTION: Although obstructive sleep apnoea syndrome (OSAS) is usually a lifelong condition, little is known about compliance with nasal continuous positive airway pressure (nCPAP) over longer periods of follow up. METHODS: Long term acceptance of nCPAP was evaluated retrospectively using a survival analysis in 137 consecutive patients who started nCPAP therapy for OSAS between 1985 and 1993. RESULTS: During a mean follow-up of 9.2 +/- 4.7 years, 30 patients died, 5 were lost of follow-up and 30 patients stopped their treatment most of them during the first 5 years. In compliant patients, the median value of daily nCPAP use was 7.5 hours. Kaplan Meier analysis showed that 82% of patients were still using nCPAP at 5 years, 77% at 10 years and 61% at 15 years. Multivariate analysis showed that OSAS severity was an independent predictor of long-term nCPAP use. The rate of nCPAP acceptance at 10 years was 82% in patients with an apnoea-hypopnoea index (AHI) > or = 30 compared to 58% in patients with AHI < 30. CONCLUSION: nCPAP is a suitable long-term therapy for OSAS, particularly in patients with more severe disease, with more than 80% of patients continuing to be compliant with treatment at 10 years.

Aged↗
PubMed2004

Economic arguments for the immediate management of moderate-to-severe obstructive sleep apnoea syndrome.

The objective of this study was to measure the impact of a 6-month delay in the diagnosis and treatment of patients with moderate obstructive sleep apnoea syndrome (OSAS) (apnoea/hypopnoea index (AHI) < 30) or severe OSAS (AHI > or = 30) on daytime sleepiness, cognitive functions, quality of life and healthcare expenditure (hospitalisations, medical visits, complementary tests, biological tests and drug prescriptions). In addition, this study aimed to analyse the incremental cost effectiveness ratios related to daytime sleepiness or quality of life following immediate introduction of treatment in these two populations. This study was conducted as a multicentre randomised controlled trial and carried out at two teaching hospitals in France. A total of 171 patients were followed for 6 months, with 82 patients randomised to group 1 "immediate polysomnography" and 89 in group 2 "polysomnography within 6 months". Patients with severe OSAS were deprived of a significant improvement of their daytime sleepiness (5.1 +/- 5.0 at the Epworth Sleepiness Scale score in group 1 versus 0.2 +/- 3.4 in group 2) and quality of life (12.4 +/- 13.3 at the Nottingham Health Profile score in group 1 versus 0.7 +/- 10.1 in group 2) during the waiting time. The impact of delayed management in subjects with less severe OSAS only concerned daytime sleepiness (1.1 +/- 3.3 in group 1 versus 0.3 +/- 4.3 in group 2). Delayed treatment did not affect cognitive functions or healthcare expenditure regardless of the severity of the disease. Incremental cost effectiveness ratios related to rapid introduction of treatment were significantly lower in the patients with more severe OSAS. These results provide fairly clear medical and economic arguments in favour of early management of patients with more severe forms of obstructive sleep apnoea syndrome.

Adolescent↗
PubMed2003

Impaired glucose-insulin metabolism in males with obstructive sleep apnoea syndrome.

The aim of this cross-sectional study was to evaluate the frequency of type-2 diabetes and impaired glucose tolerance (IGT) in a large clinic-based male population presenting various degrees of obstructive sleep apnoea syndrome (OSAS) and to analyse the relationship between OSAS and glucose-insulin metabolism. Male patients (n=595) with suspected OSAS underwent both nocturnal polysomnography and a 2-h oral glucose-tolerance test with measurements of fasting and postload blood glucose and plasma insulin. Insulin sensitivity was evaluated by the ratio of fasting glucose to fasting insulin. OSAS was diagnosed in 494 patients, while 101 patients were nonapnoeic snorers. Type-2 diabetes was present in 30.1% of OSAS patients and 13.9% of nonapnoeic snorers. IGT was diagnosed in 20.0% of OSAS patients and 13.9% of nonapnoeic snorers. Fasting and postload blood glucose increased with severity of sleep apnoea. Insulin sensitivity decreased with increasing severity of sleep apnoea. In addition to body mass index and age, the apnoea/hypopnoea index independently influenced postload blood glucose and insulin sensitivity. The authors conclude that in a clinic-based sample of patients, obstructive sleep apnoea syndrome is associated with a high frequency of type-2 diabetes and impaired glucose tolerance. The relationship between sleep-disordered breathing and impaired glucose-insulin metabolism is independent of obesity and age.

Adult↗
PubMed1998

Disruption and sequence identification of 2,000 genes in mouse embryonic stem cells.

The dramatic increase in sequence information in the form of expressed sequence tags (ESTs) and genomic sequence has created a 'gene function gap' with the identification of new genes far outpacing the rate at which their function can be identified. The ability to create mutations in embryonic stem (ES) cells on a large scale by tagged random mutagenesis provides a powerful approach for determining gene function in a mammalian system; this approach is well established in lower organisms. Here we describe a high-throughput mutagenesis method based on gene trapping that allows the automated identification of sequence tags from the mutated genes. This method traps and mutates genes regardless of their expression status in ES cells. To facilitate the study of gene function on a large scale, we are using these techniques to create a library of ES cells called Omnibank, from which sequence-tagged mutations in 2,000 genes are described.

Animals↗
PubMed1998

A computational role for dopamine delivery in human decision-making.

Recent work suggests that fluctuations in dopamine delivery at target structures represent an evaluation of future events that can be used to direct learning and decision-making. To examine the behavioral consequences of this interpretation, we gave simple decision-making tasks to 66 human subjects and to a network based on a predictive model of mesencephalic dopamine systems. The human subjects displayed behavior similar to the network behavior in terms of choice allocation and the character of deliberation times. The agreement between human and model performances suggests a direct relationship between biases in human decision strategies and fluctuating dopamine delivery. We also show that the model offers a new interpretation of deficits that result when dopamine levels are increased or decreased through disease or pharmacological interventions. The bottom-up approach presented here also suggests that a variety of behavioral strategies may result from the expression of relatively simple neural mechanisms in different behavioral contexts.

Cerebral Cortex↗
PubMed1995

Bee foraging in uncertain environments using predictive hebbian learning.

Recent work has identified a neuron with widespread projections to odour processing regions of the honeybee brain whose activity represents the reward value of gustatory stimuli. We have constructed a model of bee foraging in uncertain environments based on this type of neuron and a predictive form of hebbian synaptic plasticity. The model uses visual input from a simulated three-dimensional world and accounts for a wide range of experiments on bee learning during foraging, including risk aversion. The predictive model shows how neuromodulatory influences can be used to bias actions and control synaptic plasticity in a way that goes beyond standard correlational mechanisms. Although several behavioural models of conditioning in bees have been proposed, this model is based on the neural substrate and was tested in a simulation of bee flight.

Animals↗
PubMed1989

[Absence of nocturnal decrease in blood pressure in 24-hour blood pressure monitoring: an indication of secondary hypertension].

Non invasive 24 hours ambulatory blood pressure monitoring was performed in 81 patients with secondary hypertension (renoparenchymatous nephropathy n = 15, diabetic nephropathy n = 10, Conn's disease n = 4, renal artery stenosis n = 15, pheochromocytoma n = 2, hemodialysis patients n = 15 and patients after kidney transplantation n = 20). The results were compared to 201 patients with essential hypertension. The results showed that 98.5% of patients with essential hypertension have a nightly decline in blood pressure of at least 15 mmHg (systolic + diastolic), whereas 69% of patients with secondary hypertension showed either an attenuated circadian rhythm or no circadian rhythm. Patients with pheochromocytoma who had a night time increase in blood pressure demonstrated the greatest difference to the essential hypertension collective followed by patients with diabetic nephropathy, Conn's disease and the group of patients after kidney transplantation. After successful treatment of the condition leading to hypertension circadian periodicity returned in some patients. In summary these results suggest that the absence of a night time decline in blood pressure during 24-hour-ambulatory monitoring is an indication of secondary hypertension.

Adrenal Gland Neoplasms↗