Comparative vasodilator effects of nitroglycerin, pentaerythritol trinitrate and biometabolites, and other organic nitrates

Previous studies in man have shown pentaerythritol (PE) trinitrate, given either sublingually or orally, produces a prolonged hypotensive effect. The coronary vasodilator and systemic vasodepressor activities of PE trinitrate and its metabolites, PE dinitrate, PE mononitrate and PE, were evaluated in dogs to determine whether the metabolites were active and contributory. Coronary vasodilator activity was estimated with a flow transducer placed on the left anterior descending artery, and reduction of arterial pressure was determined directly via the femoral artery. Quantitative comparisons were made from dose-response curves established for nitroglycerin (ng), PE nitrates, and other common organic nitrates after intrajugular administration. Increase of coronary blood flow and reduction of arterial pressure were proportionally related, and the proportionality was the same for all drugs. Relative to NG, the potency of PE trinitrate was about 20 percent, erythrityl tetranitrate 12 percent, and isosorbide dinitrate 3.5 percent. The ratios of vasodilator activity of PE trinitrate and its metabolities were: PE trinitrate 100; PE dinitrate 1.5; PE mononitrate 0.5; and PE O. Tachyphylaxis was observed after close-order injections of NG or PE trinitrate. In addition, there was cross tolerance between NG and PE trinitrate and also between PE trinitrate and its less active metabolites.     

Therapeutic equivalency of two lidocaine preparations

Twenty-five volunteers were studied as to the onset and duration of action of two commercial brands of lidocaine. One and two percent concentrations of the preparations were tested intradermally using a double-blind, cross-over protocol. Both needle-drop and electrical stimulation techniques were employed as the source of pain stimulus. Five additional subjects were studied in a dose-ranging study using a placebo and lidocaine concentrations of 0.25%, 0.50%, 0.75% and 1.0%; this experiment was conduced to determine the sensitivity of the experimental methods. Both the needle-drop and electrical stimulation techniques were able to distinguish the 0.25% preparation from placebo and from the other concentrations of 1% and 2%. The two preparations were found to be statistically equivalent at concentrations of 1% and 2% and could be used interchangeably in clinical procedures.     

On the sensitivity of regression and regressors.

Acknowledges the corrections and clarifications of the author's (see record 1976-29043-001) equal weights theorem offered by J. E. Laughlin (see record 1979-02690-001) and R. M. Pruzek and B. C. Frederick (see record 1979-02691-001). It is shown that least squares estimators of regression parameters are very unstable under some conditions. Alternative estimation procedures are surveyed, and their widespread utilization is urged. The appropriateness of the conditions of the author's equal weights theorem is discussed. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Safety restraints for children travelling in motor vehicles

The parents of 202 children were questioned about their use of safety restraints for their children while they were passengers in a motor vehicle. The result of the survey shows a low incidence of use of safety restraints by both parents and their children and that the type used for children was, in the majority of cases, both inadequate and dangerous. There was a correlation between the use of safety restraints by both parent and child on the day of questioning, but no association was found between the use of these restraints and the social class, educational standard achieved, income group, home language or home province of the parents. Neither was there any association between the use of safety restraints and a history of previous traffic accidents which had involved the family or close friends. In South Africa, the number of deaths in childhood as a result of motor vehicle accidents exceed those from the same cause in the United Kingdom. We consider that the medical profession in this country should inform the public of the desirability of fitting and using safety restraints of the correct type for children while they are passengers in motor vehicles. Reasons for the high incidence of serious injuries to children who are passengers in motor vehicles are reviewed and the methods of restraining children of different ages are discussed.     

G-protein-coupled receptor chromatographic stationary phases. 2. Ligand-induced conformational mobility in an immobilized beta2-adrenergic receptor

Membranes from a HEK-293 cell line expressing the beta(2)-adrenergic receptor (beta(2)-AR) have been immobilized on an artificial membrane liquid chromatographic stationary phase. The resulting phase was packed into a glass column (1.8 x 0.5 (i.d.) cm) and used in on-line chromatographic system. Frontal displacement affinity chromatography was used to determine the dissociation constants (K(d)) of CGP 12177A (552.6 nM) and (S)-propranolol (84.3 nM). Zonal displacement chromatography using CGP 12177A as the marker and racemic mixtures of the antagonists nadolol and propranolol demonstrated that the immobilized beta(2)-AR retained its ability to specifically bind these compounds. Similar experiments with (R)- and (S)-propranolol demonstrated that the immobilized receptor retained its enantioselectivity as (S)-propranolol displaced the CGP 12177 marker to a great extent that the (R)-enantiomer. The addition of the agonist butoxamine to the mobile phase increased the retention of the CGP-12177A as did the addition of the agonist fenoterol. These results indicate that the immobilized beta(2)-AR retained its ability to undergo ligand-induced conformational changes. The data from this study suggest that the immobilized beta(2)-AR can be used to screen for ligand binding interactions in both the resting and active states of the receptor.     

Haemodynamic effects of rocuronium during fentanyl anaesthesia: comparison with vecuronium

Haemodynamic variables were measured following administration of rocuronium 0.6 mg.kg-1 or vecuronium 0.08 mg.kg-1 (approximately equivalent to 2 x ED95 doses) in patients anaesthetized with fentanyl 50 micrograms.kg-1 and scheduled to undergo elective coronary artery bypass grafting. There were increases in stroke volume index (+15%) and cardiac index (+11%), and a decrease in pulmonary capillary wedge pressure (-25%) following administration of rocuronium (P < 0.05). The changes in heart rate (+7%), mean arterial pressure (-5%), systemic vascular resistance (-12%) and other measured or derived indices were insignificant. In comparison the administration of vecuronium was associated with decreases in heart rate (-7%), mean pulmonary artery pressure (-17%), central venous pressure (-15%) and the rate-pressure product (-9%) (P < 0.05). The changes in mean arterial pressure (-7%), cardiac index (-6%) and systemic vascular resistance (-8%) following vecuronium were insignificant. There were no differences in any of the variables between rocuronium and vecuronium. The absolute values of all variables were, however, within acceptable clinical limits. There was no evidence of histamine release in any patient. The present study shows that rocuronium 0.6 mg.kg-1 is associated with changes of only small magnitude in haemodynamic variables.     

CBC and differential in VLBW infants

PURPOSE: This study tested the adequacy of established leukocyte indices in infants < or = 1,200 gm birth weight and < or = 32 weeks gestation. DESIGN: Charts of all admissions to the NICU from March 1991 through September 1994 were retrospectively reviewed. SAMPLE: All infants (n = 131) were outborn and admitted to the NICU within 24 hours after birth. MAIN OUTCOME VARIABLE: The leukocyte indices obtained during the first 72 hours after birth were plotted as a function of time in hours. RESULTS: Mode of delivery significantly affected total leukocyte count and absolute neutrophil count; sex and use of prenatal steroids did not. Ranges for total leukocyte count, absolute neutrophil count, and immature/total neutrophil (I:T) ratio demonstrate that normal values are variable and change over time. PRACTICE RECOMMENDATIONS: The wide distribution of values found, coupled with differences noted by mode of delivery, make normative data difficult to apply. The clinician must question the appropriateness of routinely obtaining a complete blood count and the clinical utility of the results.