Early morning surge in blood pressure.

Early-morning blood pressure is generally viewed as an important therapeutic target, for two reasons. First, for antihypertensive agents taken once daily in the morning, the timing of the trough plasma drug level, and thereby the lowest pharmacodynamic effect, often coincides with the early morning rise in blood pressure and heart rate. Evidence has been accumulated to suggest that blood pressure control throughout the 24 h period may be necessary to gain complete benefit from antihypertensive medication. In fact, in a longitudinal study, the regression of cardiac hypertrophy in patients with hypertension was more accurately predicted by treatment-induced changes in average 24 h ambulatory blood pressure than by clinic or home-monitored blood pressure readings. The other reason for the importance of morning blood pressure is that cardiovascular risk is heightened at this time of day. A morning surge in sympathetic activity alters haemodynamic forces and predisposes vulnerable coronary atherosclerotic plaques to rupture. At the same time as this risk of plaque rupture is greatest, circadian variations in haemostatic and fibrinolytic factors result in morning hypercoagulability and hypofibrinolysis, promoting the formation of intraluminal thrombi. We recently showed that, in older hypertensives, a greater morning blood pressure surge, mediated at least in part by an exaggerated alpha-sympathetic activity, is associated with more advanced silent cerebrovascular disease as well as a higher future incidence of stroke. The early morning surge in blood pressure could become a new therapeutic target for preventing target-organ damage and subsequent cardiovascular events in hypertension. Of greatest interest is the potential benefit of a chronotherapeutic approach, involving, for example, long-acting chronoformulations, which has not yet been extensively studied.

Antioxidant defenses in rat intestine and mesenteric lymph.

Dietary oxysterols can reach the circulation and this may contribute to atherosclerosis, where lipid oxidation is thought to be important. There is also evidence that, in rats, peroxidized lipids are absorbed and transported into lymph [Aw TY, Williams MW, Gray L. Absorption and lymphatic transport of peroxidized lipids by rat small intestine in vivo: role of mucosal GSH. Am J Physiol 1992; 262: G99-G106], although the method used to detect lipid peroxides lacked specificity. We tested whether intragastric administration of vegetable oils containing triglyceride hydroperoxides (TG-OOH) to rats resulted in detectable lipid hydroperoxides in mesenteric lymph. Using sensitive HPLC with postcolumn chemiluminescence detection, we were unable to detect hydroperoxides of triglycerides, cholesterylesters or phospholipids during the course of lipid absorption, and lymph levels of ascorbate, urate, alpha-tocopherol and ubiquinol-9 did not change significantly. By contrast, we observed a striking reducing activity judged by the efficient reduction of administered ubiquinones-9 and -10 to the corresponding ubiquinols. Exposure of rat lymph and isolated chylomicrons to aqueous peroxyl radicals revealed patterns of antioxidant consumption and lipid hydroperoxide formation similar to those described previously for human extravascular fluids and isolated lipoproteins, respectively. In particular, rates of TG-OOH formation in lymph and chylomicrons were very low to undetectable as long as ascorbate and/or ubiquinols were present, but subsequently proceeded in a chain reaction despite the presence of alpha-tocopherol. These studies demonstrate that rat intestine and mesenteric lymph possess efficient antioxidant defenses against preformed lipid hydroperoxides and (peroxyl) radical mediated lipid oxidation. We conclude that dietary lipid hydroperoxides or postprandial oxidation of lipids are not likely to contribute to these particular forms of oxidized lipids in circulation and aortic tissue.

Beneficial effect of salmon roe phosphatidylcholine in chronic liver disease.

Phosphatidylcholine (PC), especially dilinoleoyl-PC, has been reported to be effective in preventing hepatic fibrosis in chronically alcohol-fed baboons. Continuous hepatic inflammation predisposes the structure of the liver to fibrosis. Since n-3 polyunsaturated fatty acids (PUFA) have been shown to exhibit an anti-inflammatory effect, we tested the hypothesis that n-3 PUFA PC as a dietary supplement has a beneficial effect on chronic liver disease susceptible to fibrosis. Salmon roe phospholipids, 90% of which are PC, were extracted and encapsulated. Almost a third of the PC fatty acids were docosahexaenoic acid (22:6 n3) and 10% were eicosapentanoic acid (20:5 n3). About 1600 mg/day of the phospholipids was administered for six months to six chronic liver disease patients, four with hepatitis B infection (three with cirrhosis, one with chronic hepatitis), one with hepatitis C virus cirrhosis and one with alcoholic cirrhosis. There was no change in the results of blood chemistry studies related to liver function, except in globulin, which decreased from 3.80 g/dl to 3.67 g/dl (p < 0.05). Among the lipid parameters, HDL-cholesterol, apolipoprotein A-I and apolipoprotein E increased significantly. Although this was a small trial, n-3 PUFA PC may be beneficial in the treatment of chronic liver diseases.

Effects of Shimotsu-to on the microcirculation of the bulbar conjunctiva and hemorheological parameters in normal subjects.

The effects of 'Shimotsu-to' (Si-Wu-Tang in Chinese), one of the most important prescriptions for 'ketsukyo' and 'oketsu' syndrome in traditional Chinese medicine, on the microcirculation of bulbar conjunctiva and the hemorheological parameters were examined in ten healthy volunteers. After one hour of oral administration of Shimotsu-to extract, the blood flow rate and the blood flow volume significantly increased and the DEA (maximum diameter of the column of intravascular erythrocyte aggregation) decreased. The whole blood viscosity declined at middle and high shear rates, but both the plasma viscosity and the erythrocyte deformability were not effected. These results suggest that Shimotsu-to has a salutary effect on the microcirculation through a decrease in the whole blood viscosity.

Kinetics and uptake in vivo of oxidatively modified lymph chylomicrons.

The metabolism of oxidized chylomicrons (ox-CMs) was investigated in vivo. CMs from rats fed corn, linseed, or fish oil were oxidized by incubation with 2,2'-azobis(2-amidinopropane)hydrochloride (AAPH) or sodium hypochlorite (NaOCl). Oxidized CMs had a rapid phase of clearance, followed by a slow phase. Clearance of ox-CMs was decreased for corn oil but increased for linseed and fish oil particles. Differences in rats of uptake between CM types or treatment were independent of the rate of remnant formation, but were instead a consequence of decreased clearance. A greater triglyceride-to-cholesteryl ester ratio in liver suggested that there was less lipolysis of ox-CM triglyceride prior to uptake. Hepatic uptake of ox-CMs was decreased, whereas there was increased uptake in spleen. However, the uptake by Kupffer cells of ox-CMs was 43% of total liver uptake after AAPH treatment and 59% after NaOCl treatment, compared with 21% for control CMs. Collectively, our data show that oxidation can have differential effects on the rate of clearance of CMs and that ox-CMs are preferentially cleared by the reticuloendothelial system.

Synthesis and antitumor activity of spergualin analogues. I. Chemical modification of 7-guanidino-3-hydroxyacyl moiety.

Many analogues and derivatives of an antitumor antibiotic, spergualin, were synthesized, and the relationships between the structure and the activity against mouse L-1210 tumor were studied. Both modification of the 15-hydroxyl group and alteration of chain-length of the omega-guanidinoacyl moiety affected the activity. 15-Deoxyspergualin (18, 1-amino-19-guanidino-11-hydroxy-4,9,12-triazanonadecane-10,13-d ion e) and its analogue 25 (1-amino-21-guanidino-11-hydroxy-4,9,12-triazauneicosane-10,13-dio ne) had strong activity, superior to that of spergualin.

Adrenal epinephrine in hyperuricemia induced by hypothalamic stimulation of the rat.

Peripheral neurological mechanisms involved in hyperuricemia following ventromedial hypothalamic electrical stimulation was studied in the conscious rat. The intensity of 0.2 mA was near the maximum intensity of stimulation current producing a linear increase in plasma uric acid throughout the 15-min period of stimulation, as well as a subsequent rise and fall of plasma allantoin. Bilateral adrenal demedullation abolished the stimulation-induced hyperuricemia and markedly impaired the accompanying rise of allantoin. Prior treatment of the animal with hexamethonium significantly inhibited the uric acid increase, but did not reduce the allantoin elevation so markedly. Moreover, propranolol eliminated both responses of these plasma purine metabolites, whereas phentolamine greatly increased the response. It is concluded therefore that the hypothalamic stimulation-induced rise of plasma uric acid is the result of acceleration of epinephrine release from the adrenal medulla and that, whereas some unknown extra-adrenal mechanism may be partially involved, the primary part of the accompanying allantoin elevation is explained by the combined effects of the increased uric acid and the hepatic uricase.