[Echocardiographic assessment of the left ventricular fractional shortening/end-systolic stress relation in untreated hypertensive patients]

The present study was designed to assess the left ventricular (LV) function by the fractional shortening (FS)/end-systolic stress (ESS) relation in untreated hypertensive patients.

METHODS

Two patient groups were examined: group 1 was made up of 50 patients with essential mild hypertension (44 +/- 14 years) and group 2 consisted of 16 normotensives (35 +/- 12 years). LV mass, endocardial FS, mid-wall FS and meridional ESS were measured according to the classic formulas, as well as the 24-hour ambulatory blood pressure (ABP). FS/ESS relation was analysed in hypertensive patients by 2 different ways: 1 degree graphically, with the 95% confidence interval of the normal FS/ESS relation as a reference: 2 degrees statistically, by comparing the observed FS values with those FS value expected from ESS, using equations derived from normal subjects (McMemar chi 2 test, or binomial rule).

RESULTS

The graphic examination allowed for the identification of a depressed, normal or increased LV function in, respectively, 7, 31 and 12 patients, using the endocardial FS/ESS relation, against 30, 18 and 2 patients, using the mid-wall FS/ESS relation. Likewise, the statistical analysis of the differences between the observed FS values and the expected FS values showed 13 discrepancies, all of them being related to an overestimation of the LV function, an assessed by the endocardial FS/ESS relation (p < 0.01). Such a trend turned out to be more significant in patients with an increased ABP (n = 31; p < 0.05) than in "white coat" hypertensives (n = 9; p < 0.08): in contrast, it was of the same extent in patients with an increased LV mass (n = 17; p < 0.05) as in those with a normal LV mass (n = 33; p < 0.05).

CONCLUSIONS

1/After adjustment for ESS, mid-wall FS (a direct measure of myocardial fiber shortening) was more often decreased than endocardial FS (reflecting chamber dynamics). 2/Mid-wall FS was also found to be a better tool for assessing LV function in patients with normal LV mass, and, to a lesser extent, in "white coat" hypertensives.

Doping Graphitic and Carbon Nanotube Structures with Boron and Nitrogen

Composite sheets and nanotubes of different morphologies containing carbon, boron, and nitrogen were grown in the electric arc discharge between graphite cathodes and amorphous boron-filled graphite anodes in a nitrogen atmosphere. Concentration profiles derived from electron energy-loss line spectra show that boron and nitrogen are correlated in a one-to-one ratio; core energy-loss fine structures reveal small differences compared to pure hexagonal boron nitride. Boron and carbon are anticorrelated, suggesting the substitution of boron and nitrogen into the carbon network. Results indicate that singlephaase CyBxNx as well as separated domains (nanosize) of boron nitride in carbon networks may exist.