OBJECTIVE: Hypertension is often seen in obstructive sleep apnea (OSA) and is characterized by increased sympathetic activity, depressed baroreflex and accentuated vascular responsiveness. The objective of this study was to investigate the effects of the new T-selective calcium channel blocker mibefradil on invasively measured blood pressure (BP) and heart rate in hypertensive patients with OSA. METHODS: The present study was a double-blind, randomized and placebo-controlled before and after trial in two parallel groups. Fifty-three men aged 23 69 years with systemic hypertension and OSA were recruited from the Outpatient Department of the Marburg University Sleep Laboratory and hospitalized for 10 days. Mibefradil (50 mg) or placebo were given orally in the morning for 8 days. The main outcome measure was the mean arterial (radial) BP monitored continuously during nocturnal sleep and during standardized daytime physical and psychological performance testing. RESULTS: Mibefradil lowered mean arterial BP and heart rate with (SD) during the entire measurement period compared with placebo: -7.25 (9.59) vs -2.11 (8.43) mmHg (P=0.039) and -4.83 (5.94) vs -1.34 (4.13) bpm (P=0.022), respectively. Both effects were observed during nocturnal sleep and performance testing, including graded exercise. Adverse events did not differ compared with placebo. CONCLUSION: Mibefradil is an effective but well-tolerated antihypertensive that also lowers heart rate over 24 h in OSA, in conditions known to increase BP.

Adult↗

PubMedDate not supplied

Effects of BCH 325 (Pro-D-Phe-Pro-Gly) on open field behavior after chronic stress procedure.

The chronic stress model is an animal model relevant to clinical depression. The chronic stress rat group showed a significant decrease in motor activity. The reduced open field activity could be restored by subchronic treatment with imipramine and doxepine. Subchronic treatment with haloperidol, amphetamine and methylglucamine orotate was not able to alter the reduced open field activity. Previous treatment with a beta-casomorphin derivative (BCH 325) significantly antagonized the effect of chronic stress. The findings point out an antidepressant-like effect of BCH 325.

Amphetamine↗

PubMedDate not supplied

Reduction of electromagnetic interference from a commercially available MR-compatible flow simulator.

Electromagnetic interference (EMI) associated with the electronics of a commercially available computer controlled flow simulator substantially decreases the quality of the MR image. The effect of a custom-built radiofrequency shield on its spectral emission, and the corresponding signal-to-noise ratio measured for the image of a standard phantom, were determined. The results demonstrate the elimination of EMI and a significant improvement in image quality.

Electromagnetic Phenomena↗

PubMedDate not supplied

Flow in elliptical vessels calculated for a physiological waveform.

Understanding the nature of pulsatile flow is an important issue in haemodynamics, especially the initiation and progression of vascular disease. The geometry of a non-circular vessel was idealised to an elliptical cross-section, and the dynamic properties of the flow were calculated for a physiological waveform. The Fourier harmonics for a common carotid waveform were determined, and the velocity profile and wall shear stress were calculated from the superposition of the individual contributions from each harmonic. The effects of ellipticity on the flow pattern were found to be significant. The velocity profile along the major axis of the elliptical cross-section developed a flattened peak, which widened as the vessel became more elliptical. Wall shear stress demonstrated an angular dependence in elliptical vessels, where the point of minimum shear stress was located at the end of the major axis. Comparison with a cylindrical vessel demonstrated a 3% decrease in peak wall shear stress (tau = 2.96, N.m(-2)) at the end of the major axis, and 10% in the mean wall shear stress (tau = 0.44 N. m(-2)), for an elliptical vessel (epsilon = 0.8). The temporal average wall shear stress, which has been associated with atherogenic sites, also displayed a minimum at the end of the major axis that decreased with more elliptical cross-sections.

Blood Flow Velocity↗

PubMedDate not supplied

Conformational changes in proteins induced by low temperatures: an infrared study.

Infrared spectra of hemoglobin (met-hemoglobin) and myoglobin were recorded in the temperature range -110 degrees C to 30 degrees C. On cooling hydroalcoholic solutions of hemoglobin, the spectra indicate a conformational change (revealed by the appearance of a band at 1665 cm-1) compatible with the appearance of distortions in its alpha-helical structure. In the case of myoglobin smaller effects are observed. These conformational changes are entirely reversible and do not occur in frozen aqueous solutions.

Animals↗