A systematic review of vascular and endothelial function: effects of fruit, vegetable and potassium intake.

AIM: To review the relationships between: 1) Potassium and endothelial function; 2) Fruits and vegetables and endothelial function; 3) Potassium and other measures of vascular function; 4) Fruits and vegetables and other measures of vascular function. DATA SYNTHESIS: An electronic search for intervention trials investigating the effect of potassium, fruits and vegetables on vascular function was performed in MEDLINE, EMBASE and the Cochrane Library. Potassium appears to improve endothelial function with a dose of >40 mmol/d, however the mechanisms for this effect remain unclear. Potassium may improve measures of vascular function however this effect may be dependent on the effect of potassium on blood pressure. The effect of fruit and vegetables on endothelial function independent of confounding variables is less clear. Increased fruit and vegetable intake may improve vascular function only in high risk populations. CONCLUSION: Increasing dietary potassium appears to improve vascular function but the effect of increasing fruit and vegetable intake per se on vascular function is less clear.

Effect of high potassium diet on endothelial function.

BACKGROUND AND AIMS: Increased potassium intake is related to reduced blood pressure (BP) and reduced stroke rate. The effect of increased dietary potassium on endothelial function remains unknown. The aim was to determine the effect of increased dietary potassium from fruit and vegetables on endothelial function. METHODS AND RESULTS: Thirty five healthy men and women (age 32 ± 12 y) successfully completed a randomised cross-over study of 2 × 6 day diets either high or low in potassium. Flow mediated dilatation (FMD), BP, pulse wave velocity (PWV), augmentation index (AI) and a fasting blood sample for analysis of Intercellular Adhesion Molecule-1 (ICAM-1), E-selectin, asymmetric dimethylarginine (ADMA) and endothelin-1 were taken on completion of each intervention. Dietary change was achieved by including bananas and potatoes in the high potassium and apples and rice/pasta in the low potassium diet. Dietary adherence was assessed using 6 day weighed food diaries and a 24 h urine sample. The difference in potassium excretion between the two diets was 48 ± 32 mmol/d (P = 0.000). Fasting FMD was significantly improved by 0.6% ± 1.5% following the high compared to the low potassium diet (P = 0.03). There were no significant differences in BP, PWV, AI, ICAM-1, ADMA or endothelin-1 between the interventions. There was a significant reduction in E-selectin following the high (Median = 5.96 ng/ml) vs the low potassium diet (Median = 6.24 ng/ml), z = -2.49, P = 0.013. CONCLUSION: Increased dietary potassium from fruit and vegetables improves FMD within 1 week in healthy men and women but the mechanisms for this effect remain unclear. CLINICAL TRIAL REGISTRY: ACTRN12612000822886.

Postprandial effects of potassium supplementation on vascular function and blood pressure: a randomised cross-over study.

BACKGROUND AND AIMS: Endothelial dysfunction, as assessed by flow mediated dilatation (FMD) is an early event in atherosclerosis and an independent predictor of cardiovascular events. The effect of potassium supplementation on endothelial function and blood pressure (BP) in the postprandial state is not known. The aim of this study was to assess endothelial function using FMD in healthy volunteers. METHODS AND RESULTS: Thirty-two normotensive volunteers received a meal with 36 mmol potassium (High K) and a control 6 mmol potassium (Low K) meal on 2 separate occasions in a randomized order. FMD and BP were measured while participants were fasting and at 30, 60, 90 and 120 min after the meal. There was a postprandial decrease in FMD in both groups. FMD decreased overall less after the High K meal compared to the Low K meal (meal effect p < 0.05). Both meals produced a postprandial decrease in BP at 30 min which returned to baseline levels by 120 min. No significant differences in BP were observed between meals. FMD and systolic BP were negatively correlated at 90 (r = -0.54-0.55, p < 0.01) and 120 min (r = -0.42-0.56, p < 0.01) after both meals. CONCLUSIONS: A high potassium meal, which contains a similar amount of potassium as 2.5 serves of bananas, can lessen the postprandial reduction in brachial artery FMD when compared to a low potassium meal.

Uso de un compuesto a base de gel de hidróxido de bismuto coloidal con pectina en la diarrea aguda / Use of a gel compound with colloidal bismuth hydroxide and pectin in acute diarrhea

El estudio tuvo un año de duración. Se evaluó la eficacia terapéutica de un compuesto a base de un gel de hidróxido de bismuto coloidal al 3% con pectina (Crema de Bismuto Chobet) en la diarrea aguda del lactante. El estudio se realizó en 48 lactantes afectados de diarrea aguda de menos de 24 horas de evolución. La investigación utilizó metodología a doble ciego, fue randomizada y controlada con placebo. Ambos grupos de tratamiento fueron similares en cuanto a características demográficas y etiopatogénicas. El porcentaje de niños mejorados clínicamente a las 24 horas de tratamiento y la reducción del número de deposiciones fue del 45,8% en el grupo placebo y del 83,4% en el grupo tratado con la Crema de Bismuto (p

Effects of trace metal compounds on HIV-1 reverse transcriptase: an in vitro study.

The effect of 44 different metal ions (Ag+, Al3+, As(O-)2, Au3+, Ba2+, Be2+, Bi3+, Cd2+, Ce3+, CO2+, Cr(O2-)4, Cr3+, Cs+, Cu2+, Fe3+, Fe2+, Ga3+, Ge4+, Hg2+, Ir4+, La3+, Li+, Mn2+, MO6+, Ni2+, OS4+, Pb2+, Pt4+, Rb+, Rh3+, Sb5+, Se(O2-)4, Se(O2-)3, Sn2+, Sr2+, Th4+, T1+, U(O2+)2, V(O-)3, VO2+, W(O2-)4, Y3+, Zn2+, and Zr4+) on the activity of the reverse transcriptase (RT) of the human immunodeficiency virus (HIV-1) was investigated in vitro. For this study, the RT activity assay was carried out by means of an enzyme-linked immunosorbent assay (ELISA) kit, using the template/primer hybrid poly(A) oligo(dT)15, which required some modifications: (1) possible interfering metal chelators (such as EDTA) in the original lysis buffer were avoided, and a new buffer (50 mM Tris-NO3, pH 7.8) was used throughout; (2) an amount of 2 ng of RT per well was considered to be optimal after checking the linearity of the reaction with increasing amounts of enzyme; (3) an incubation temperature of 37 degrees C and an incubation time of 1 h were chosen after preliminary studies in a wide range of temperature and time. At an incubation temperature > or = 40 degrees C, there was a dramatic loss of enzymatic activity. In addition, when RT alone was preincubated for 1 h at 5 degrees C, 25 degrees C, and 37 degrees C, there was a large (83%) loss of activity at 37 C as compared to that at 5 degrees C. These results are indicative of enzyme thermolability, which is higher in the absence of substrates. The effect of metal ions on RT activity was tested using two different metal salt concentrations (10(-4) M and 10(-5) M). Under such experimental conditions, the presence of five metal ions (Pt4+, Ag+, Rh3+, Zn2+, and Hg2+) decreased the RT activity in a dose-response fashion. The observed order of effectiveness with respect to inhibition was Pt4+ > Ag+ > Rh3+ > Zn2+ = Hg2+. Estimated mean inhibitory concentrations (IC50) were 7.8 microM for (NH4)2PtCl6, 14.1 microM for AgNO3, 46.8 microM for RhCl3, 53.7 microM for Zn(SO)4, and 56.2 microM for Hg(NO3)2. Because these data are of the same order of magnitude as the corresponding values related to other RT inhibitors used in anti-AIDS therapy, metal compounds or their derivatives could give an interesting contribution in the development of new RT inhibitors for clinical use.

Hepatitis B and C virus sexual transmission among homosexual men.

OBJECTIVE: We estimated hepatitis B virus (HBV) and hepatitis C virus (HCV) sexual transmission among homosexual men. METHODS: Two hundred twenty-eight homosexually active men attending two clinical centers and presenting no risk factors except for sexual exposure were interviewed, and a blood sample was drawn. HBV marker test was performed using enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay, and HCV was tested using ELISA-2 and recombinant immunoblot assay-2. RESULTS: HBV and HCV infection prevalence rates were 34.4% and 12.7%, respectively. Using logistic regression analysis including sexual exposure and controlling for confounders, we found that anal receptive intercourse (odds ratio [OR] = 4.01; 95% confidence interval [CI] = 1.34-11.94), duration of homosexuality (OR = 3.43; 95% CI = 1.29-9.12), insertive anilingus (OR = 2.02; 95% CI = 1.06-3.87), and sexually transmitted diseases (OR = 1.87; 95% CI = 1.00-3.47) were independently associated with the risk of HBV sexual transmission. We did not find any association between sexual behavior and HCV transmission. CONCLUSIONS: Sexual behavior is a plausible explanatory factor of HBV sexual transmission among homosexual men. Further evidence is needed to elucidate the occurrence and the efficiency of HCV sexual transmission in the absence of other risk factors.

Paradoxical effect of oxygen administration on breathing stability following post-hyperventilation apnoea in lambs.

1. Oxygen administration is thought to suppress periodic breathing (PB) by reducing carotid body activity, and yet earlier experiments in neonates have shown that PB incidence may be increased following the application of hyperoxia. To clarify this paradox, we studied the changes in the pattern of PB that occur following administration of oxygen in a lamb model of PB. 2. PB was induced in eleven of seventeen anaesthetized lambs following passive hyperventilation with air. When oxygen was administered during PB, the pattern was first enhanced, as evidenced by a sudden decrease in the ratio of the ventilatory duration to the apnoeic pause duration, and then suppressed, as evidenced by a progressive return to stable breathing which was associated with an increase in minute ventilation. 3. Five of the six lambs that did not show PB following passive hyperventilation with air could be made to do so if oxygen was substituted for air as the inspired gas following passive hyperventilation. 4. Five of the eleven lambs that showed PB following hyperventilation with air responded to the application of oxygen during PB by switching to a gross form of episodic breathing consisting of long apnoeic pauses followed by equally long periods of breathing during which minute ventilation fell progressively with time. 5. We conclude that when applied against a background of arterial hypoxaemia, oxygen has a destabilizing influence on ventilation in that (a) it accentuates the unstable breathing that occurs during PB, (b) it induces PB in lambs that exhibited stable breathing in air, and (c) it may precipitate episodic breathing.

Source of respiratory drive during periodic breathing in lambs.

In order to investigate the mechanisms underlying periodic breathing (PB), we studied the initiation of breathing after passive hyperventilation in 14 anaesthetised 10-20 day old lambs. Eight of the lambs exhibited PB following post-hyperventilation apnea (PHA), with an epoch duration of 82.4 +/- 14.2 sec (mean +/- SEM), a cycle duration of 9.7 +/- 0.7 sec and a ratio of ventilatory duration to apnea duration (V-A ratio) of 1.24 +/- 0.32. The remaining lambs showed stable breathing patterns following PHA. The ventilatory response to isocapnic hypoxia was significantly greater in the group that had PB (-7.2 +/- 1.0 ml min-1% Sao2-1 kg-1) than in the animals that did not (-2.5 +/- 1.0 ml min-1%Sao2-1 kg-1). Using experimentally determined ventilatory response curves to O2 and CO2 we calculated that the swings in Sao2 and Paco2 during PB generated chemical drive that accounted for only 16.2% of the ventilatory oscillations observed during PB. Much of the remaining drive appeared to originate in the 'switch-on' characteristics of the respiratory controller, in lambs that exhibited periodic breathing, when breathing began after PHA ventilation jumped abruptly from zero to 55.1% of the eupneic ventilation. The magnitude of this jump in ventilation accounted for 51.9% of the amplitude of ventilatory oscillations that occur during PB. We speculate that this previously unrecognised feature of the respiratory controller, together with an elevated sensitivity to hypoxaemia, play crucial roles in generating PB in the infant.

Incorporating psychological debriefing techniques within a brief group psychotherapy programme for the treatment of post-traumatic stress disorder.

BACKGROUND: The Royal Air Force Wroughton Post-Traumatic Stress Disorder (PTSD) Rehabilitation Programme is described. It comprised a 12-day structured in-patient 'course' of group psychotherapy and day-case group follow-up sessions over a one-year period. Psychological debriefing was the main therapeutic technique employed. METHOD: This is a 'before and after' open outcome study. A comprehensive assessment protocol confirmed the presence and severity of PTSD and measured co-morbid psychopathological status, occupational and social function longitudinally. RESULTS: A highly significant global response to treatment is demonstrated in the 34 subjects included in the study, with 85.3% not fulfilling the DSM-III-R criteria for PTSD at one year after treatment. CONCLUSIONS: Further controlled studies assessing the value of psychological debriefing techniques in the treatment of established PTSD are required.

Changes in the temporal structure of periodic breathing with postnatal development in preterm infants.

The progressive decrease in the periodic cycle duration (PCD) of periodic breathing with postnatal age in term infants has been previously reported by a number of authors and is thought to be associated with peripheral chemoreceptor maturation. We hypothesized that a similar decrease should be observed in preterm infants. Therefore, in this study we measured the changes in PCD with postnatal age in a small group of preterm (n = 4) infants followed longitudinally (36 afternoon nap studies) over the first 6 mo postnatally. PCD declined in these infants from 17.1 +/- 3.3 s (mean +/- 2 SD) at 9 d to 9.8 +/- 3.2 s (mean +/- 2 SD) at 105 d. The regression slope was -0.072 s/d. Beyond 105 d there was no change in PCD up to 6 mo postnatally. We found no significant difference between active and quiet sleep. These results are similar to results previously published in term infants but apparently contradict recent data on a group of preterm infants. Possible reasons for this discrepancy are discussed. By examining long epochs of periodic breathing in these infants we also identified characteristic changes in PCD and V/A ratio, defined as the duration of the ventilatory period divided by the duration of the apneic interval. V/A ratio fell from the start of an epoch from 1.21 +/- 0.08 (mean +/- SEM) to a minimum of 0.62 +/- 0.03 and then increased again to 0.8 +/- 0.05 at the end of the epoch.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of venous oxygenation on arterial desaturation rate during repetitive apneas in lambs.

While arterial oxygen desaturation during apnea is a common occurrence in adults and infants, the factors determining the rate of desaturation are poorly understood. We describe a theoretical model which suggests that arterial desaturation during an apneic episode occurs in two stages. In the initial stage (stage 1) the oxygen store in the lung is depleted, while in the second phase of the desaturation process (stage 2) tissue oxygen needs are met predominantly by depletion of the blood store. Our model predicts that preapneic venous oxygenation (SvO2) will strongly influence the rate of the desaturation in stage 1 but not in stage 2. We therefore examined the effect of changing preapneic SvO2 on the rate of arterial oxygen desaturation (SaO2) during stage 1 and stage 2 apnea in anaesthetised 10-20 day-old lambs. Preapneic arterial oxygen saturation was maintained constant. In agreement with the model's prediction there were two stages to the desaturation process and during stage 1 a significant increase in SaO2 was observed when preapneic SvO2 was lowered; SaO2 was -3.1 +/- 0.4%.sec-1 when SvO2 = 47.4 +/- 2.1% increasing to -5.8 +/- 0.7%.sec-1 when SvO2 = 28.3 +/- 1.2%. During stage 2, SaO2 was -1.62 +/- 0.07%.sec-1 and was independent of preapneic SvO2, also in accord with the model's prediction. In order to assess whether the accelerated desaturation rate we observed in stage 1 could have resulted from a decline in lung volume during apnea rather than lower levels of SvO2, we repeated the experiment with CPAP applied. Under these conditions SaO2 continued to be greater at lower preapneic SvO2 levels. In summary, lowered preapneic SvO2 has a potent influence on SaO2 during stage 1 of the desaturation process but not during stage 2.

Determination of alpha-tocopherol in plasma and erythrocytes by high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method for the determination of alpha-tocopherol in plasma or erythrocytes with photodiode-array detection is described. Using this detector, information about the spectrum, absorption maxima and purity of the peak is obtained. Tocopherol was separated on a 5-microns Spherisorb ODS-2 column with methanol as element at a flow-rate of 1.0 ml/min. As little as 100 microliters of plasma or 150 microliters of erythrocytes can be used for accurate analysis with direct extraction without saponification. The speed, specificity, sensitivity and reproducibility of this technique make it particularly suitable for the routine determination of alpha-tocopherol in plasma or erythrocytes.