Ambulatory nocturnal oximetry and sleep questionnaire-based findings in 38 patients with end-stage renal disease.
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BACKGROUND: Patients with end-stage renal diseases (ESRD) have an increased risk of sleep-disordered breathing. With regard to this disorder, controversy persists about prevalence, cost-effective assessment and socio-economical relevance. METHODS: Therefore, we performed, for the first time, overnight ambulatory oximetry in combination with a sleep questionnaire in 38 unselected patients with ESRD and 37 healthy controls. An oxygen desaturation index (ODI) >15, defined as >15 falls in oxygen saturation of > or =4% per h, was observed more frequently in ESRD patients than in healthy controls (47 vs. 3%, P<0.001). RESULTS: In general, the results derived from the assessment of the Epworth Sleepiness Scale (ESS) as well as those from the visual analogue scale (VAS) did not reflect the ODI values of the respective patient population. Interestingly, 88% of ESRD patients with the questionnaire finding 'excessively loud snoring' had an ODI of >15 as compared with 13% without this complaint (P<0.05). Furthermore, 77% of ESRD patients with a systolic blood pressure >140 mm Hg and a body mass index (BMI) >25, had an ODI of >15. The percentage of ESRD patients with a professional activity was higher in the absence of sleep-disordered breathing (63 vs. 21%, P<0.05). CONCLUSION: 'Excessively loud snoring' and a BMI >25 combined with hypertension are risk factors for sleep-disordered breathing in ESRD patients. Nocturnal oxygen desaturations are assessed efficiently by ambulatory oximetry and correlate with relevant biological and socio-economical parameters in ESRD patients. (+info)
Human insulin gene insertion in mice. Effects on the sleep-wake cycle?
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Recently, insulin synthesis and the presence of an insulin receptor have been demonstrated in the brain. Intracerebroventricular infusion of insulin causes a selective increase in the amount of slow-wave sleep. In the present study, the sleep-wake cycle of transgenic mice, with or without habenular neuronal expression of the human insulin gene, was studied to investigate the possible role of brain insulin as a sleep modulator. Slow-wave sleep duration was increased in those mice expressing human insulin in the habenula. However, it is possible that this effect was not due to expression of the insulin transgene, but to the genetic background of one of the parental strains (CBA) used for insertion of the transgene. Users of transgenic mice should be aware of this possibility and be cautious in interpreting results when hybrid embryos are used as transgene recipients. (+info)
Energy metabolism in African Americans: potential risk factors for obesity.
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BACKGROUND: Recent reports have identified a lower resting metabolic rate in African Americans than in whites, but most studies included only females and used short-term measurements with ventilated-hood systems. OBJECTIVE: Our objective was to compare 24-h measurements of energy metabolism between African American and white women and men using a respiratory chamber. DESIGN: Thirty-eight African American (x +/- SD: 32 +/- 7 y of age, 24 +/- 10% body fat) and 288 white (31 +/- 7 y of age, 26 +/- 12% body fat) subjects spent 24 h in a respiratory chamber for measurement of 24-h energy expenditure (24EE), sleeping metabolic rate (SMR), 24-h respiratory quotient (24RQ), and substrate oxidation rates. RESULTS: After adjustment for sex, age, and body composition (by hydrodensitometry), African Americans had lower SMR (-301 +/- 105 kJ/d; P < 0.01) and higher 24RQ (0.014 +/- 0.004; P < 0.001) than whites, whereas 24EE was similar. A sex-specific analysis, using a subset of 38 whites with an equal sex distribution and similar age and body weight, revealed that African American women had lower SMR (-442 +/- 182 kJ/d; P < 0.05) and lower 24EE (-580 +/- 232 kJ/d; P < 0.05), but similar 24RQ values compared with white women. African American men tended to have lower SMRs than white men (-355 +/- 188 kJ/d; P = 0. 07), but had higher 24RQ values, accounting for a 992 +/- 327-kJ/d lower 24-h fat oxidation rate (P < 0.005). CONCLUSIONS: These data not only confirm the findings of a lower metabolic rate in African American than in white women, but also suggest that fat oxidation is lower in African American men than in white men. (+info)
Nonlinear, fractal, and spectral analysis of the EEG of lizard, Gallotia galloti.
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Electroencephalogram (EEG) from dorsal cortex of lizard Gallotia galloti was analyzed at different temperatures to test the presence of fractal or nonlinear structure during open (OE) and closed eyes (CE), with the aim of comparing these results with those reported for human slow-wave sleep (SWS). Two nonlinear parameters characterizing EEG complexity [correlation dimension (D2)] and predictability [largest Lyapunov exponent (lambda(1))] were calculated, and EEG spectrum and fractal exponent beta were determined via coarse graining spectral analysis. At 25 degrees C, evidence of nonlinear structure was obtained by the surrogate data test, with EEG phase space structure suggesting the presence of deterministic chaos (D2 approximately 6, lambda(1) approximately 1. 5). Both nonlinear parameters were greater in OE than in CE and for the right hemisphere in both situations. At 35 degrees C the evidence of nonlinearity was not conclusive and differences between states disappeared, whereas interhemispheric differences remained for lambda(1). Harmonic power always increased with temperature within the band 8-30 Hz, but only with OE within the band 0.3-7.5 Hz. Qualitative similarities found between lizard and human SWS EEG support the hypothesis that reptilian waking could evolve into mammalian SWS. (+info)
Increased levels of circulating ICAM-1, VCAM-1, and L-selectin in obstructive sleep apnea syndrome.
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Obstructive sleep apnea syndrome (OSAS) may be one of the most important risk factors of cardiovascular disorders, although the exact mechanism remains to be elucidated. In the present study, we hypothesized that OSAS-induced hypoxic stress might be involved in the etiology of cardiovascular disorders by activating adhesion molecules, including intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and L-selectin. To examine this hypothesis, we measured circulating ICAM-1, VCAM-1, and L-selectin levels before and after sleep in OSAS patients and age-matched controls. The circulating ICAM-1, VCAM-1, and L-selectin levels increased in the OSAS patients before sleep compared with the normal subjects (ICAM-1: 392.9 +/- 48.5 vs. 201.2 +/- 55.0 ng/ml, P < 0.05; VCAM-1: 811.0 +/- 87.8 vs. 574.2 +/- 42.7 ng/ml, P < 0.05; L-selectin: 1,386.6 +/- 77.9 vs. 1,038.8 +/- 78.6 ng/ml, P < 0.01, respectively). After sleep, significantly greater levels of ICAM-1 and L-selectin, but not VCAM-1, were observed in the OSAS group. These observations suggest that OSAS-induced hypoxia activates adhesion molecules, resulting in the important risk factor of cardiovascular disorders. Treatment of OSAS can be, therefore, a potential approach to prevention of cardiovascular events. (+info)
Monitoring respiratory function and sleep in the obese Vietnamese pot-bellied pig.
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Development of drug treatments for obstructive sleep-disordered breathing has been impeded by the lack of animal models. The obese pig may be a suitable animal model, as it has been reported to experience sleep-disordered breathing resembling human obstructive sleep apnea. The purpose of this paper is to describe in detail techniques for chronic instrumentation of the obese Vietnamese pot-bellied pig and to study respiratory function during sleep. Under general anesthesia, four obese pigs were instrumented for long-term recording of intrapleural and tracheal pressures, genioglossal EMG, and bioelectric signals related to sleep. A custom-fitted face mask was used to record respiratory variables including airflow, snoring, and expired CO(2). Most chronic instrumentation provided robust signals for up to 6 wk after installation. All pigs displayed sleep-disordered breathing characterized by increased resistance to airflow, snoring, inspiratory flow limitation, and possible sleep disruption. Apneas and hypopneas were not a feature of breathing during sleep in these animals. Nonetheless, this animal preparation may be useful for exploring possible drug treatments for obstructive sleep-disordered breathing. (+info)
Diurnal variations of blood pressure in dogs.
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Using the telemetry system, we measured the blood pressure (BP) invasively in seven adult mongrels while unanesthetized and unbound. Post-operative BP after implanting the telemetry BP transmitter showed temporarily high values due to the invasive nature of the surgery. It was, however, observed that BP gradually decreased thereafter, and showed settled trends from the eighth day post-operatively. When we took the average of the systolic, mean and diastolic BP at hourly intervals for each of the dogs once their BP had settled, a twin peak diurnal variation (at 8:00 and 19:00) was observed. Moreover, significantly high values (p < 0.05) were identified in active state compared with when sleeping or at rest. The 24 hr BP measured by the telemetry system in seven normal dogs resulted in the following values: systolic 123.4 +/- 7.9 mmHg, mean 91.1 +/- 5.6 mmHg, and diastolic 74.5 +/- 4.9 mmHg. (+info)
Biological clocks.
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Circadian rhythms describe biological phenomena that oscillate with an approximately 24-hour cycle. These rhythms include blood pressure, body temperature, hormone levels, the number of immune cells in blood, and the sleep-wake cycle. In this paper, we will focus on common genes between species that are responsible for determining the circadian behavior, especially some transcription factors (i.e., switch genes) that serve to regulate many circadian rhythm genes. The intent of this summary is to introduce the common molecular mechanism of biological clocks between flies and humans and then to describe the research from three laboratories that was presented in the session. (+info)