Impact of smoking cessation on ambulatory blood pressure and heart rate in postmenopausal women.

BACKGROUND: Smoking and hypertension interact to increase the incidence of cardiovascular disease; however, little is known about the effects of smoking cessation on blood pressure (BP) control. We prospectively evaluated the impact of smoking cessation on clinic and ambulatory BP and heart rate (HR) in stage 1 hypertensive and normotensive postmenopausal women. METHODS: A total of 66 women were randomly assigned using a 3:1 randomization scheme to immediate smoking cessation or to a wait list control group. Clinic and ambulatory BP and HR, and 24-h urinary catecholamine concentrations were obtained at baseline and again at 6 weeks. Carbon monoxide levels and self-report were used to assess compliance with smoking cessation. RESULTS: Ambulatory monitoring showed that the awake SBP decreased by 3.6+/-1.9 mm Hg in the treated subjects who quit smoking (n=19), whereas in the control group (n=15) there was an increase of 1.7+/-2.4 mm Hg (P=.045). Awake HR decreased after smoking cessation by 7+/-1 beats/min and did not change (0+/-1 beat/min) in the control group (P=.001). Blood pressure and HR did not significantly change during sleep after smoking cessation. Changes in the awake HR correlated with changes in urinary epinephrine concentrations (r= 0.58, P=.001), and norepinephrine concentrations (r= 0.45, P=.001), There was no significant change in clinic systolic BP, diastolic BP, or HR between groups. CONCLUSIONS: Smoking cessation reduces systolic BP and HR during the daytime, when patients typically smoke. These hemodynamic changes are due in part to reductions in sympathetic nervous system activity.

Naltrexone treatment of comorbid alcohol and cocaine use disorders.

Naltrexone (NTX) has been shown to be efficacious for the treatment of alcohol dependence. Since alcohol and cocaine use disorders commonly co-occur, we conducted a randomized, double-blind, placebo-controlled trial of NTX 50 mg/day in 64 subjects with comorbid alcohol and cocaine use disorders. Although subjects in both groups reduced their consumption of both alcohol and cocaine during the 8-week trial, there was no consistent advantage to NTX over placebo treatment. We conclude that, due to behavioral, neurochemical, or other factors, individuals with both alcohol and cocaine use disorders are distinct from those dependent on alcohol alone, and that NTX at a dosage of 50 mg/day is not efficacious in this patient population. Several factors, including medication dosage, length of treatment, sample size and attrition rate, limit the interpretation of these findings. Consequently, we recommend that subsequent trials of NTX to reduce the risk of relapse in patients with comorbid alcohol and cocaine use disorders take these issues into account.

Isomerization of retinyl palmitate using conventional lipid extraction solvents.

The use of a chloroform-ethanol-water solvent system for the direct extraction of retinyl palmitate isomers from fortified food products was previously shown to be unsuitable because significant isomerization of all-trans-retinyl palmitate occurred during the extraction. This study investigated the extent of isomerization of retinyl palmitate in various extraction solvents when subjected to gold fluorescent laboratory light. Purified solutions of all-trans-retinyl palmitate in hexane were diluted with methyl t-butyl ether, hexane, methylene chloride, and stabilized chloroform and subjected to gold fluorescent laboratory light for 2, 4, and 6.5 h. Similar solutions were subjected to light or kept in the dark for 3.5 h. All-trans-, 9-cis-, and 13-cis-retinyl palmitate esters in the solutions were determined by using normal phase high performance liquid chromatography with fluorometric detection. Results demonstrated a noticeable increase in the 9-cis-retinyl palmitate concentration and a corresponding decrease in all-trans-retinyl palmitate concentration with time, in chloroform and methylene chloride compared with hexane. Chlorinated solvents in the absence of light did not promote isomerization of retinyl palmitate. Use of chlorinated solvents for the extraction of vitamin A esters should be avoided because they promote isomerization of retinyl palmitate when subjected to light, including gold fluorescent laboratory light.

High pressure liquid chromatographic determination of vitamins A and E in cereal products.

A rapid method for the simultaneous determination of vitamins A and E in fortified cereal products has been developed. Saponification of retinyl or tocopheryl esters is not required, permitting direct injection of the extracted lipids onto the high pressure liquid chromatographic column without sample cleanup. Elution times of 2.46 and 3.40 min were determined for retinyl palmitate and tocopheryl acetate, respectively, using a muPorasil column and an isocratic mobile phase of hexane-chloroform (85 + 15) with a flow rate of 1.5 mL/min. The average recovery of retinyl palmitate was 99.2% (std dev. 4.28), and the average recovery of tocopheryl acetate was 94.9% (std dev. 4.10) in 2 cereals containing corn, oat, rice, and wheat. No significant amounts of naturally occurring tocopherols were found in the cereals.

Determination of urinary 4-pyridoxic acid using high performance liquid chromatography.

A high performance liquid chromatographic method is presented for the determination of the vitamin B6 metabolite, 4-pyridoxic acid, in urine. Urine samples are treated with trichloroacetic acid to precipitate protein. An aliquot of the supernatant is chromatographed using 0.033 M phosphate buffer containing 5% (v/v) methanol (pH 2.2), a fluorometric detector and a commercial reverse phase octadecylsilica column. The high precision of the method and the absence of interfering compounds have been demonstrated. This method provides a rapid, sensitive, and quantitative technique for the measurement of urinary 4-pyridoxic acid for use in metabolic and nutritional studies.

Vitamin B-6 activity for rats of epsilon-pyridoxyllysine bound to dietary protein.

The biological activity of protein bound epsilon-pyridoxyllysine residues in a phosphopyridoxyl-bovine serum albumin (PP-BSA) preparation was evaluated. Previous studies have demonstrated that pyridoxal phosphate may bind to food proteins as epsilon-pyridoxyllysine complexes during processing and storage. The present research, employing PP-BSA as a model, was initiated to determine the nutritional consequences of epsilon-pyridoxyllysine formation in foods. The concentration of epsilon-pyridoxyllysine residues in the PP-BSA was determined spectrophotometrically and chromatographically. Rat bioassay of the PP-BSA revealed that epsilon-pyridoxyllysine exhibited 60% activity relative to the molar potency of pyridoxine. These results suggest the partial release of bound vitamin B-6 possibly by in vivo enzymatic hydrolysis of epsilon-pyridoxyllysine. The presence of PP-BSA in a test diet containing 0.25 microgram added pyridoxine per g of diet inhibited the utilization of approximately half of the free pyridoxine by the rats. It is postulated that the observed inhibition resulted from an antivitamin B-6 effect of intact epsilon-pyridoxyllysine. This effect requires further investigation.

Automated analysis of thiamine, ascorbic acid, and vitamin A.

Methods currently used in most nutrient analysis laboratories are the classical AOAC methods. One of the major challenges facing the analytical chemist is the need for new or modified quantitative and reliable nutrient assay methods, which are rapid and less labor intensive. Recently, numerous vitamin assays have been published which use continuous flow and high pressure liquid chromatographic techniques. This paper deals with some of the recent methods reported for analysis of thiamine and ascorbic acid, using continuous flow wet chemistry, and high pressure liquid chromatography for vitamin A in food products.