Endothelial function as an end-point in interventional trials: concepts, methods and current data

SURROGATE END-POINTS: Pharmacotherapy of cardiovascular disease has been increasingly validated in large interventional trials to assess its efficacy, safety and costs. As endpoints, morbidity and mortality are evaluated. More recently, surrogate end-points have been included in interventional trials, both to increase our understanding of pathogenic mechanisms and for their potential use as markers of risk in patients. ENDOTHELIAL FUNCTION: The endothelium lies in a strategic anatomical position between the circulating blood and vascular smooth muscle and hence is a major local mediator of cardiovascular function. Also, endothelial cells are a target for mechanical forces and cardiovascular risk factors in the circulation. Thus, it is not surprising that their function becomes impaired at an early stage in the disease process. The cells are able to produce numerous proteins and mediators. This review focuses on nitric oxide and endothelin-1, which are endothelium-derived relaxing and constrictor factors, respectively. Nitric oxide also prevents platelet adhesion and aggregation and the adhesion of monocytes. Both substances also affect vascular structure in that nitric oxide inhibits while endothelin stimulates vascular smooth muscle proliferation and migration. MEASUREMENTS OF ENDOTHELIAL FUNCTION: Endothelial function and the effects of nitric oxide and endothelin in particular can be evaluated in the coronary circulation by quantitative coronary angiography and Doppler flow wire, and in the peripheral circulation with plethysmography and new ultrasound/Doppler devices. In these experimental set-ups, lipid-lowering drugs and angiotensin converting enzyme (ACE) inhibitors have been evaluated. Lipid-lowering drugs improve endothelium-dependent vasodilation in the coronary and forearm circulation of patients with hyperlipidemia and atherosclerosis. Similarly, ACE inhibitors improve coronary vasomotion in patients with coronary artery disease and normal lipid levels. In hypertension, ACE inhibitors have failed to improve endothelium-dependent vasodilation, while studies with other drugs are planned. CONCLUSIONS: Endothelial function can now be assessed precisely in patients in vivo, in both the coronary and the peripheral circulation. Tests can detect early dysfunction in patients with a risk of cardiovascular disease and the possible effects of drugs on endothelial function. Large interventional trials are needed to establish how far endothelial dysfunction can or cannot predict clinical outcome.     

Efficient lymphocyte migration across high endothelial venules of mouse Peyer's patches requires overlapping expression of L-selectin and beta7 integrin

Lymphocyte migration into lymphoid organs is regulated by adhesion molecules including L-selectin and the beta7 integrins. L-selectin and alpha4beta7 are predominantly hypothesized to direct the selective migration of lymphocytes to peripheral lymph nodes and the gut-associated lymphoid tissues, respectively. To further characterize interactions between L-selectin and beta7 integrins during lymphocyte recirculation, mice deficient in both receptors (L-selectin/beta7 integrin-/-) were generated. The simultaneous loss of L-selectin and beta7 integrin expression prevented the majority of lymphocytes (>95% inhibition) from attaching to high endothelial venules (HEV) of Peyer's patches and other lymphoid tissues during in vitro binding assays. Moreover, the inability to bind HEV eliminated the vast majority of L-selectin/beta7 integrin-/- lymphocyte migration into Peyer's patches during short-term and long-term in vivo migration assays (>99% inhibition,p < 0.01). The lack of lymphocyte migration into Peyer's patches correlated directly with the dramatically reduced size and cellularity (99% reduced) of this tissue in L-selectin/beta7 integrin-/- mice. High numbers of injected L-selectin/beta7 integrin-/- lymphocytes remaining in the blood of wild-type mice correlated with markedly increased numbers of circulating lymphocytes in L-selectin/beta7 integrin-/- mice. Loss of either L-selectin or the beta7 integrins alone resulted in significant but incomplete inhibition of Peyer's patch migration. Collectively, the phenotype of L-selectin/beta7 integrin-/- mice demonstrates that these two receptors primarily interact along the same adhesion pathway that is required for the vast majority of lymphocyte migration into Peyer's patches.     

Losartan but not verapamil inhibits angiotensin II-induced tissue endothelin-1 increase: role of blood pressure and endothelial function

Endothelin partially mediates angiotensin (Ang) II-induced vascular changes in vivo. This study investigated the effects of the angiotensin type 1 receptor antagonist losartan and the calcium channel blocker verapamil on vascular reactivity and tissue endothelin-1 levels in aortas of Wistar-Kyoto rats treated for 2 weeks with Ang II (200 ng x kg(-1) x min(-1)). Ang II increased systolic blood pressure (39+/-4 mm Hg, P<0.05). Concomitant treatment with losartan abolished the Ang II-induced pressure increase (P<0.05), whereas verapamil reduced it only partially (P<0.05). In the aortas of rats with Ang II-induced hypertension, tissue endothelin-1 content was increased threefold and contractions to endothelin-1 were impaired (P<0.05). Interestingly, these alterations were normalized by losartan (P<0.05) but not by verapamil. Hence, there was a strong, negative correlation between contractions to endothelin-1 and tissue endothelin-1 content (r=-0.733, P<0.0001). In contrast, both antihypertensive drugs normalized impaired endothelium-dependent relaxations to acetylcholine and reduced the sensitivity of vascular smooth muscle to sodium nitroprusside compared with Ang II-treated rats (P<0.05). Ang II-induced hypertension enhanced endothelium-dependent contractions to acetylcholine, and these were normalized by either drug. In conclusion, these findings suggest that long-term treatment with Ang II modulates endothelin-1 protein expression in the rat aorta. Although both antihypertensive agents lowered blood pressure and normalized endothelial function, only losartan prevented the increase in tissue endothelin-1 content, suggesting that angiotensin type 1 receptor antagonists but not calcium antagonists modulate tissue endothelin-1 in vivo.     

Delivery of salbutamol to nonventilated preterm infants by metered-dose inhaler, jet nebulizer, and ultrasonic nebulizer

An isocratic reversed-phase high-performance liquid chromatographic method with ultraviolet detection at 230 nm has been developed for the determination of paclitaxel in human plasma. Plasma samples were prepared by a selective one-step liquid-liquid extraction involving a mixture of acetonitrile-n-butyl chloride (1:4, v/v). Paclitaxel and the internal standard docetaxel were separated using a column packed with ODS-80A material, and a mobile phase consisting of water-methanol-tetrahydrofuran-ammonium hydroxide (37.5:60:2.5:0.1, v/v). The calibration graph for paclitaxel was linear in the range 10-500 ng/ml, with a lower limit of quantitation of 10 ng/ml, using 1 ml plasma samples. The extraction recoveries of spiked paclitaxel and docetaxel to drug-free human plasma were 89.6+/-8.52 and 93.7+/-5.0%, respectively. Validation data showed that the assay for paclitaxel is sensitive, selective, accurate and reproducible. The assay has been used in a single pharmacokinetic experiment in a patient to investigate the applicability of the method in vivo.     

Identification and characterization of the KlCMD1 gene encoding Kluyveromyces lactis calmodulin

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is the major cause of morbidity and death after lung transplantation. Therapy has focused on augmented immunosuppression with a variety of agents. Although transient responses are often achieved, sustained remission has been unusual. The outcome of cytolytic therapy for BOS at our center has been analyzed and is reported. METHODS: Between July 1988 and July 1994, 233 patients underwent lung transplantation at Barnes-Jewish Hospital. Among 207 recipients (88.8%) who survived more than 3 months, 81 recipients (39%) had development of BOS; 48 of these patients underwent 64 courses of treatment with a cytolytic agent (antilymphocyte globulin, antithymocyte globulin, or OKT3 monoclonal antibody). The cases of BOS were retrospectively analyzed to determine the impact of cytolytic therapy. RESULTS: The 4-year survival rate was significantly greater in recipients without BOS than in those with BOS (82.8% vs 46.0%; p < .05). Various clinical factors, including diagnosis, forced expiratory volume in 1 second at onset of BOS, presence or absence of pathologically proven bronchiolitis obliterans, type of transplant operation, cytomegalovirus serologic status, and cytomegalovirus pneumonia, were examined, but no significant predictor of survival after the development of BOS was discerned. The mean decrement in forced expiratory volume in 1 second was significantly reduced by cytolytic therapy (-23.5% +/- 2.3% in the 3 months before therapy vs -9.9% +/- 3.5% in the 3 months after the therapy; p < .002). Nevertheless, the stage of BOS progressed over time in spite of therapy in most cases, and only 4 recipients (4.9%) with BOS remained in a lower BOS stage 2 years after treatment. CONCLUSIONS: Recipients with BOS had a significantly lower survival rate than recipients without BOS. No predictor of survival after the onset of BOS was identified. Although cytolytic therapy decreased the rate of decline in pulmonary function in the 3 months after treatment, the stage of BOS ultimately progressed in most patients.     

Ruminal degradation of tannin‐treated legume meals

The inefficiency of protein utilisation by ruminants fed protein concentrates (based on legume meals) causes serious economic loss and environmental damage owing to their rapid hydrolysis and deamination in the rumen. Thus efforts aimed at slowing the ruminal fermentation of such feeds are needed, and recent studies have observed potentially positive effects of tannins on ruminant nutrition under certain circumstances. Tannins are a complex group of naturally occurring plant polyphenols characterised by their ability to bind with proteins. This property of tannins is considered responsible for the decreased ruminal digestibility of forages both in vivo and in vitro. Under that perspective, commercial tannic acid was added at three proportions (10, 25 and 50 g kg^?1 on a dry matter basis) to four different legume meals (horse bean, kidney bean, soybean and pea), and the effect on in situ dry matter and crude protein ruminal disappearance was assessed. The results confirmed the dose‐dependent (although not persistent after 48 h) slowing of in situ digestibility, this effect being significant at the highest tannin treatment when compared with untreated samples. Scanning electron microscopy revealed that soybean seed endosperm cell walls were protected from digestion by the ruminal microbiota, while the digestion of starch granules was relatively unaffected by tannic acid. Electrophoresis of the protein fractions confirmed the lower digestibility of tannin‐treated seeds as well as the relative lack of alteration of the electrophoretic profile of individual proteins. Implications for the digestion of concentrates in ruminants are discussed. Copyright © 2004 Society of Chemical Industry     

Isotropic isotopy and symplectic null sets

Capacity is an important numerical invariant of symplectic manifolds. This paper studies when a subset of a symplectic manifold is null, i.e., can be removed without affecting the ambient capacity. After examples of open null sets and codimension-2 non-null sets, geometric techniques are developed to perturb any isotopy of a loop to a hamiltonian flow; it follows that sets of dimension 0 and 1 are null. For isotropic sets of higher dimensions, obstructions to the perturbation are found in homotopy groups of the orthogonal groups.     

Pancreatic pseudocysts associated with chronic pancreatitis--early and late results of 1367 operations

The authors hereby review the data of 1367 operations for pancreatic pseudocysts. The surgical procedures of choice in particular pancreatic pathologies are analysed in the light of early morbidity and mortality, as well as long term follow-up results. The best operations for pancreatic pseudocysts have been the internal drainage procedures, which resolve the pathological alterations without the necessity of pancreatic resection. The treatment of chronic pancreatitis may require combined surgical procedure, such as cysto-Wirsungo-gastrostomy. The pancreatic resections performed for the treatment of small pseudocysts in the pancreatic head have been superseded by the less invasive blunt, forced cysto-duodenostomies, representing better results secondary to the smaller perioperative risk for the patient. The cyst-to-stomach and cyst-to-duodenum internal drainage techniques are just as effective, but with shorter operation time, than the Roux-en-Y cysto-jejunostomies.