We hypothesise that routinely applied short sessions of slow and regular breathing can lower blood pressure (BP). Using a new technology BIM (Breathe with Interactive Music), hypertensive patients were guided towards slow and regular breathing. The present study evaluates the efficacy of the BIM in lowering BP. We studied 33 patients (23M/10F), aged 25-75 years, with uncontrolled BP. Patients were randomised into either active treatment with the BIM (n ‫؍‬ 18) or a control treatment with a Walkman (n ‫؍‬ 15). Treatment at home included either musically-guided breathing exercises with the BIM or listening to quiet music played by a Walkman for 10 min daily for 8 weeks. BP and heart rate were measured both at the clinic and at home with an Omron IC BP monitor. Clinic BP levels were measured at baseline, and after 4 and 8 weeks of treatment. Home

The effect of viscosity on the rate of catalysis of carboxypeptidase A has been tested. By use of the tripeptide carbobenzoxy-l-alanyl-l-alanyl-l-alanine [Z(L-Ala)3] as substrate, it was shown that most of the effect on the hydrolysis rate caused by the presence of 30 or 40% methanol or glycerol in aqueous solution can be ascribed to a contribution of viscosity to the catalytic rate constant, kcat. Arrhenius plots of kcat in 30 and 40% glycerol or methanol are linear and almost parallel. When the rate constants are "corrected" for the viscosity of various media, the difference between the various Arrhenius plots is considerably reduced; it vanishes, within experimental error, when the effect of the dielectric constant of the solutions is taken into account as well. It is proposed that the viscosity of the medium can influence the rate-limiting step of the enzymic reaction, which is the rate of transitions over the energy barrier preceding product formation. According to the suggested mechanism, the enzyme--substrate complex can overcome this energy barrier by viscosity-dependent structural fluctuations. The quantitative agreement between the theory and the experimental results suggests that (a) due to the temperature dependence of the viscosity of the solution, the potential energy barrier of the reaction is about 5 kcal/mol lower than the observed activation energy and (b) information about the structural flexibility of the complex can be obtained by kinetic measurements.

Objective: To examine the efficacy of a new device, which slows and regularises breathing, as a non-pharmacological treatment of hypertension and thus to evaluate the contribution of breathing modulation in the blood pressure (BP) reduction. Design and setting: Randomised, double-blind controlled study, carried out in three urban family practice clinics in Israel. Patients: Sixty-five male and female hypertensives, either receiving antihypertensive drug therapy or unmedicated. Four patients dropped out at the beginning of the study. Intervention: Self treatment at home, 10 minutes daily for 8 consecutive weeks, using either the device (n ‫؍‬ 32), which guides the user towards slow and regular breathing using musical sound patterns, or a Walkman, with which patients listened to quiet music (n ‫؍‬ 29). Medication was unchanged 2 months prior to and during the study period. Main outcome measures: Systolic BP, diastolic BP and

Application of symmetrical regression provides a more valid estimate of the systolic-on-diastolic slope and the AASI, less influenced by goodness of fit and nocturnal dipping and more sensitive to age and disease states such as hypertension and diabetes, thus providing an improved index of arterial stiffening.

The addition of hydrogen-bonded cosolvents to aqueous solutions of proteins is known to modify both thermodynamic and dynamic properties of the proteins in a variety of ways. Previous studies suggest that glycerol reduces the free volume and compressibility of proteins. However, there is no directly measured evidence for that. We have measured the apparent specific volume (V) and adiabatic compressibility (K) of a number of proteins, sugars, and amino acids in water and in 30% glycerol at pH 7.4 and 30 degrees C. The values of V and K in water and their changes induced by glycerol were extrapolated to the limit of infinite solute size. The main results were the following: (a) glycerol decreases V and K of proteins, but increases it for amino acids; (b) the V and K values of the protein interior in water were found to be 0.784 +/- 0.026 mL/g and (12.8 +/- 2.5) x 10(-6) mL/g x atm, where the glycerol reduces these values by 8 and 32%, respectively; (c) the coefficient of adiabatic compressibility of the structural component of proteins affected by the glycerol is estimated to be (50 +/- 10) x 10(-6) atm(-1), which is comparable to that of water. We propose that the glycerol induces a release of the so-called "lubricant" water, which maintains conformational flexibility by keeping apart neighboring segments of the polypeptide chain. This is expected to lead to the collapsing of the voids containing the water as well as to increase intramolecular bonding, which explains the observed effect.

Laser photodissociation of respiratory proteins is followed by fast geminate recombination competing with escape of the oxygen molecule into the solvent. The escape rate from myoglobin or hemerythrin has been shown previously to exhibit a reciprocal power-law dependence on viscosity. We have reinvestigated oxygen escape from hemerythrin using a number of viscous cosolvents of varying molecular weight, from glycerol to dextrans up to 500 kDa. In isoviscous solutions, the strong viscosity dependence observed with small cosolvents is progressively reduced upon increasing the cosolvent's molecular weight and disappears at molecular weights greater than about 100 kDa. Thus, viscosity is not a suitable independent parameter to describe the data. The power of the viscosity dependence of the rate coefficient is shown here to be a function of the cosolvent's molecular weight, suggesting that local protein-solvent interactions rather than bulky viscosity are affecting protein dynamics.

The adiabatic compressibility of several globular proteins has been measured by using an ultrasonic technique in the frequency range 0.5 to 10 MHz. The contributions to the measured-compressibility from the protein matrix .and from surface processes involving ionization of side chains and solvation effects are discussed; The internal -protein compressibility is very. low, indicating the existence of "dynamic domains" which are tentatively assigned to secondary structure elements.During the past few years, considerableinterest in the problem of fast conformational fluctuations in protein systems has developed (1-3). Many techniques have been used to study fluctuations in biomolecules. Generally they involve the study of relaxational behavior after a perturbation is applied to the system-(4). The external perturbation can take the form of.a step or a continuous sinusoidal function. We have studied the behavior ofprotein systems under continuous-wave pressure perturbation. A pressure wave in a fluid causes alternating compressions and rarefactions. Because the period is short compared with the time required for thermal equilibrium of the solution, the process is reversible and adiabatic. By using pressure waves, one can extract information about mechanical and thermal properties of the system. The frequency dependence of these properties arises from relaxational processes, yielding valuable information on the time constants of the different mechanisms involved.The theory of pressure wave propagation in solutions can be found in standard texts (for instance, see ref. 5). The adiabatic compressibility is defined by Pad = -1/V (aV/aP)s where V is the volume of the sample and P is the pressure. Pad can be obtained by a measurement ofthe density p and sound velocity c. Pad = 1/pc2. For a solution containing protein, the protein adiabatic compressibility may be determined by measuring the density and sound velocity in the solution as afunction ofprotein concentration.Adiabatic compressibilities of protein solutions have been reported (6)(7)(8)(9)(10)(11). Quite recently this method has been applied to the study of the compressibility of cytochrome c in the oxidized and reduced forms (12). The reported values for apparent protein compressibility are generally low, on the order of 10-20% of the compressibility ofwater which is a relatively incompressible liquid. This low value is generally explained by the observation that the-constituent amino acids have a negative apparent compressibility. The apparent positive value observed for, globular proteins then reflects a very compressible protein interior (8).In order to explain the increase in compressibility upon denaturation, which seems to contradict the hypothesis of a high compressibility of the protein interior, a very high local concentration of nonpolar groups is assumed for a denatured protein. Sarvazyan and Hemmes (6) discussed the possible contribution ofrelaxations to the compressibility on the basis ofsound absorption data. However, no direct measurements...

Slow breathing practiced routinely using an interactive device has demonstrated a sustained reduction in high blood pressure (BP). We reevaluated the BP response of hypertensives (n = 13) to this daily treatment for 8 weeks using 24-h ambulatory, home, and office BP measurements. A clinically significant BP reduction of similar magnitude was observed in all BP monitoring modalities during the daytime. Greater BP reductions were found for older patients and higher baseline BP. The results provide additional support for the efficacy of the device as an adjunctive lifestyle modification for treating hypertension.