Regulation and impact of cardiac lymphangiogenesis in pressure-overload-induced heart failure

AIMS

Lymphatics are essential for cardiac health, and insufficient lymphatic expansion (lymphangiogenesis) contributes to development of heart failure (HF) after myocardial infarction. However, the regulation and impact of lymphangiogenesis in non-ischemic cardiomyopathy following pressure-overload remains to be determined. Here, we investigated cardiac lymphangiogenesis following transversal aortic constriction (TAC) in C57Bl/6 and Balb/c mice, and in end-stage HF patients.

METHODS & RESULTS

Cardiac function was evaluated by echocardiography, and cardiac hypertrophy, lymphatics, inflammation, edema, and fibrosis by immunohistochemistry, flow cytometry, microgravimetry, and gene expression analysis. Treatment with neutralizing anti-VEGFR3 antibodies was applied to inhibit cardiac lymphangiogenesis in mice.We found that VEGFR3-signaling was essential to prevent cardiac lymphatic rarefaction after TAC in C57Bl/6 mice. While anti-VEGFR3-induced lymphatic rarefaction did not significantly aggravate myocardial edema post-TAC, cardiac immune cell levels were increased, notably myeloid cells at 3 weeks and T lymphocytes at 8 weeks. Moreover, whereas inhibition of lymphangiogenesis did not aggravate interstitial fibrosis, it increased perivascular fibrosis and accelerated development of left ventricular (LV) dilation and dysfunction. In clinical HF samples, cardiac lymphatic density tended to increased, although lymphatic sizes decreased, notably in patients with dilated cardiomyopathy. Similarly, comparing C57Bl/6 and Balb/c mice, lymphatic remodeling post-TAC was linked to LV dilation rather than to hypertrophy. The striking lymphangiogenesis in Balb/c was associated with reduced cardiac levels of macrophages, B cells, and perivascular fibrosis at 8 weeks post-TAC, as compared with C57Bl/6 mice that displayed weak lymphangiogenesis. Surprisingly, however, it did not suffice to resolve myocardial edema, nor prevent HF development.

Residency training in robotic surgery: The role of simulation

Simulation has become increasingly important in surgical teaching in recent years and the French National Authority for Health (HAS) recently underlined the goal and ethical priority: "never the first time on the patient". Simulation programs have been tested and validated for laparotomy and for laparoscopy, but there is not yet a validated program specific for robotic surgery. Due to substantial advances in this new technology, we have developed a program in Nancy dedicated to outside-the-operating room (OR) teaching of robotic surgery using the Da Vinci robot. This teaching is based on a combined program of theoretical teaching (e-learning) and learning of practical skills using virtual simulators (DV-Trainer®, Robotic Mentor®, DVSS®), mechanical simulators (Dome, Applied® abdominal simulators), microsurgery and wet lab using ex vivo animal organs, anesthetized animals, and cadavers. This program also emphasizes team training. The course is intended for residents in surgical training and is integrated into the specialized study diploma (DES) program for Visceral and Digestive Surgery; it also can be used by qualified surgeons who can integrate it with the Inter-University Diploma (DIU) in General Robotic Surgery for basic techniques and also for DIUs in other surgical specialties (digestive and gynecologic surgery) for robotic uses within their specialty. These courses are based on the concept of step-by-step skills acquisition and verification allowing a transition to safe clinical activity.

The role of oxidative damage in poor scalp health: ramifications to causality and associated hair growth

The oxidative stress element of unhealthy scalp leads to compromised pre-emergent hair formation and poorly formed hair as it grows. Only cosmetic solutions can minimize the impact of unhealthy hair and to achieve healthy looking and feeling hair, the scalp health must be normalized first. The objectives of this research were to both investigate whether oxidative stress was a relevant aetiological element in scalp dandruff and seborrhoeic dermatitis and whether scalp condition affects the quality of hair that grows from it. Further, this research was designed to determine whether an effective anti-dandruff shampoo would repair and protect the scalp and pre-emergent hair from oxidative stress. This study demonstrated that oxidative stress is an aetiological element relevant to the dandruff condition and that a potentiated ZPT shampoo effectively improves scalp condition, including a reduction in oxidative stress. The compromised hair condition associated with dandruff is concomitantly improved when the scalp condition is improved. It appears that there is a direct link between hair quality and scalp health.

An angiosperm-wide analysis of the gynodioecy-dioecy pathway

BACKGROUND AND AIMS

About 6 % of an estimated total of 240 000 species of angiosperms are dioecious. The main precursors of this sexual system are thought to be monoecy and gynodioecy. A previous angiosperm-wide study revealed that many dioecious species have evolved through the monoecy pathway; some case studies and a large body of theoretical research also provide evidence in support of the gynodioecy pathway. If plants have evolved through the gynodioecy pathway, gynodioecious and dioecious species should co-occur in the same genera. However, to date, no large-scale analysis has been conducted to determine the prevalence of the gynodioecy pathway in angiosperms. In this study, this gap in knowledge was addressed by performing an angiosperm-wide survey in order to test for co-occurrence as evidence of the gynodioecy pathway.

METHODS

Data from different sources were compiled to obtain (to our knowledge) the largest dataset on gynodioecy available, with 275 genera that include at least one gynodioecious species. This dataset was combined with a dioecy dataset from the literature, and a study was made of how often dioecious and gynodioecious species could be found in the same genera using a contingency table framework.

KEY RESULTS

It was found that, overall, angiosperm genera with both gynodioecious and dioecious species occur more frequently than expected, in agreement with the gynodioecy pathway. Importantly, this trend holds when studying different classes separately (or sub-classes, orders and families), suggesting that the gynodioecy pathway is not restricted to a few taxa but may instead be widespread in angiosperms.

CONCLUSIONS

This work complements that previously carried out on the monoecy pathway and suggests that gynodioecy is also a common pathway in angiosperms. The results also identify angiosperm families where some (or all) dioecious species may have evolved from gynodioecious precursors. These families could be the targets of future small-scale studies on transitions to dioecy taking phylogeny explicitly into account.

ShearWave™ Elastography BE1 multinational breast study: additional SWE™ features support potential to downgrade BI-RADS®-3 lesions

PURPOSE

To determine the benefit of ShearWave™ Elastography (SWE™) in the ultrasound characterization of BI-RADS® 3 breast lesions in a diagnostic population.

MATERIALS AND METHODS

303 BI-RADS® 3 lesions (mean size: 13.2 mm, SD: 7.5 mm) from the multicenter BE1 prospective study population were analyzed: 201 (66%) had cytology or core biopsy, and the remaining 102 had a minimum follow-up of one year; 8 (2.6%) were malignant. 7 SWE features were evaluated with regard to their ability to downgrade benign BI-RADS® 3 masses. The performance of each SWE feature was assessed by evaluating the number of lesions correctly reclassified and the impact on cancer rates within the new BI-RADS® 3' lesion group.

RESULTS

No malignancies were found with an E-color "black to dark blue", which allowed the downgrading of 110/303 benign masses (p < 0.0001), with a non-significant increase in BI-RADS® 3' malignancy rate from 2.6% to 4.1%. E-max ≤ 20 kPa (2.6 m/s) was able to downgrade 48/303 (p < 0.0001) lesions with a lower increase in BI-RADS® 3' malignancy rate (3.1%). No other SWE features were useful for reclassifying benign BI-RADS® 3 lesions.

CONCLUSION

Applying simple reclassification rules, SWE assessment of the maximum stiffness of lesions allowed the downgrading of a sub-group of benign BI-RADS® 3 lesions. This was accompanied by a non-significant increase in the malignancy rate in the new BI-RADS® 3 class.

QUANTITATIVE STUDIES OF THE PHOTOCHEMICAL DESPECIATION OF HORSE SERUM : AN APPROACH TO THE PROBLEM OF INTRAVENOUS FOREIGN PROTEIN THERAPY

1. Normal horse serum was irradiated for periods of 3 to 4 days, with visible light or with ultraviolet light of known intensity and wave length. The photosensitizer hematoporphyrin was employed in some instances. The serum was exposed to the air in thin layers, and thoroughly agitated throughout irradiation. 2. The irradiated sera were unchanged in color, and over 90 per cent of the original protein content remained precipitable by phosphotungstic acid. 3. Studies of the antigenicity of the sera were carried out on guinea pigs and rabbits. Fresh antigenicities of deviated specificity and of an activity of the order of 1/50th, 1/1,000th, and less than 1/20,000th that of normal horse serum were obtained. The residual content of material having the same antigenic specificity as normal horse serum was estimated as approximately equivalent in activity to dilutions of normal horse serum of 1 cc., 1/10 cc., and less than 1/100 cc. per litre respectively.

Evolution of reproductive systems in the genus Silene

The genus Silene contains both hermaphrodite, gynodioecious and dioecious species, dioecy being represented in three sections of the genus. To locate the events of change of reproductive systems, we compared ITS sequences of 22 species of Silene chosen throughout the whole genus, and four putative outgroup species. Gynodioecy, which is the most common reproductive system within the genus Silene and in closely related genera such as Saponaria and Dianthus, is proposed to be ancestral in the genus. Dioecy has evolved at least twice: once in the section containing S. latifolia, and once in the clade containing S. otites and S. acaulis ssp. bryoides. Evolution towards hermaphroditism, associated with evolution of selfing has also occurred at least twice, in S. gallica and S. comica.

CHRONIC DECREASE IN FLOW CONTRIBUTES TO HEART FAILURE-INDUCED ENDOTHELIAL DYSFUNCTION IN RATS

Chronic heart failure (CHF) impairs endothelium-dependent, nitric oxide (NO)-mediated dilation. This decreased dilation may be partly secondary to the chronic decrease in blood flow, but this hypothesis has not yet been tested. Thus, we assessed whether a localized, chronic increase in blood flow in vivo reverses endothelial dysfunction of small arteries in rats with CHF. Two months after coronary artery ligation or sham surgery, second-order side branches of the superior mesenteric artery were ligated in order to obtain persistently elevated blood flow (HF) in the adjacent first-order side branch compared with normal vessels (NF). One month later, responses to acetylcholine and flow-mediated vasodilatation (FMD) were assessed in vitro in an arteriograph. Chronic heart failure induced a decrease in mesenteric blood flow (374 +/- 25 and 305 +/- 27 micro L/min for sham and CHF, respectively; P < 0.05). Neither CHF nor the chronic increase in flow affected the responses to acetylcholine. Chronic heart failure decreased FMD (maximal response in sham and control 34 +/- 6 and 13 +/- 4%, respectively; P < 0.05). Chronic increases in blood flow did not modify FMD in sham, but restored FMD in CHF rats (28 +/- 4%; P < 0.05 vs CHF NF). The restored response was abolished by an inhibitor of NO synthesis (N(G)-nitro-l-arginine). Chronic heart failure did not affect the abundance of mesenteric endothelial NO synthase (eNOS) mRNA. A chronic increase in flow significantly increased the abundance of eNOS mRNA in sham rats, but only moderately and non-significantly in CHF rats. Thus, endothelial dysfunction of small arteries in CHF appears to be largely the consequence of the chronic decrease in flow.

Lack of impairment of nitric oxide-mediated responses in a rat model of high-renin hypertension

1. Angiotensin (Ang) II triggers the expression of a pro- oxidant phenotype in the vascular wall, suggesting that activation of the renin-angiotensin system (RAS) causes endothelial dysfunction in various pathological situations, such as hypertension. However, this hypothesis has been mostly tested in a setting of exogenous administration of AngII. 2. We tested the hypothesis of a role for endogenous activation of the RAS leading to oxidant stress and endothelial dysfunction in a high-renin model of hypertension (i.e. two-kidney, one-clip hypertension) in rats. One month after clipping or sham surgery, aorta were isolated from untreated rats or rats treated by the angiotensin AT1 receptor antagonist irbesartan (10 mg/kg per day). Mesenteric artery segments were also isolated from normotensive or hypertensive rats. 3. Hypertension reduced the relaxations to acetylcholine but did not affect the ratio of contractions to phenylephrine in the presence compared with the absence of a nitric oxide (NO) synthase inhibitor, used as an index of basal release of NO. 4. The free radical scavenger tempol reduced the contractions to phenylephrine in the absence, but not in the presence, of an inhibitor of NO synthesis. This index of free radical-mediated degradation of NO was not affected by hypertension. In parallel, hypertension did not affect the expression of p22phox, a component of the free radical generating enzyme reduced nicotinamide adenine dinucleotide phosphate oxidase. 5. Chronic treatment with the AT1 receptor antagonist decreased blood pressure, moderately improved the response to acetylcholine, but did not affect basal NO release in hypertensive rats, although it did increase basal NO release in normotensive rats. 6. Thus, this model of hypertension is characterized by an impaired stimulated NO release but not of basal NO release in isolated arteries. Furthermore, there was no functional evidence of an increased oxidative stress-mediated impairment of NO release. This is not in favour of a direct link between activation of the RAS and development of endothelial dysfunction in experimental hypertension.

Interest of the association clonidine-spironolactone in cirrhotic patients with ascites and activation of sympathetic nervous system

BACKGROUND

The aim of this study was to examine the effects of spironolactone, clonidine and the association of clonidine-spironolactone on renin-aldosterone and sympathetic systems, renal function, systemic hemodynamics and mobilization of ascites in 32 alcoholic cirrhotic patients with marked increase in sympathetic system.

METHODS

Measurements were taken before and after an 8-day treatment with spironolactone (200 mg/day), after an 8-day treatment with clonidine (0.150 mg/day) and 10 days after adjunction of spironolactone (200 mg/day) to clonidine.

RESULTS

Three patients abandoned the treatment or were excluded because lack of compliance. Spironolactone alone induced an increase in renin-aldosterone and sympathetic systems without any remarkable increase of natriuresis and body weight loss. Given for 8 days, clonidine alone induced a significant decrease in plasma norepinephrine associated with a significant increase in glomerular filtration rate without effect on natriuresis. In contrast, 10 days after adjunction of spironolactone to clonidine, plasma renin and aldosterone significantly decreased, natriuresis increased (from 7.4 +/- 0.7 to 41.6 +/- 3.2 mEq/24 h) and body weight decreased (from 66.03 +/- 2.3 to 63.5 +/- 2.3 kg) without adverse effects.

CONCLUSION

In cirrhotic patients with ascites and marked activation of sympathetic nervous system, spironolactone (200 mg/day) is unable to mobilize ascites. In these patients, after 8 days, clonidine decreases sympathetic activity, increases glomerular filtration rate and after 18 days, decreases plasma renin and aldosterone concentrations allowing a better action of spironolactone. The association clonidine-spironolactone enhances natriuresis and body weight loss.

[Long term surveillance of polyps and colorectal cancers]

It is necessary to assume the colorectal cancer follow-up after curative operation to detect cancer recurrence and new polyps or cancers. A good follow-up by endoscopy is also necessary for patients with colorectal polyps and for patients with familial adenomatous polyposis.

Effects of combination of low doses of angiotensin-converting enzyme inhibitor and diuretics on renal function in spontaneously hypertensive rats: comparison between acute and chronic treatment

The goal of this study was to assess the effect of acute or chronic treatment with S5590, a combination of the angiotensin-converting enzyme inhibitor perindopril (0.76 mg/kg/day) and the diuretic indapamide (0.24 mg/kg/day) on renal function in spontaneously hypertensive rats with moderate renal injury. Renal function was evaluated in conscious rats by clearance methods using labelled inulin and PAH, after catheterisation of the carotid artery, jugular vein and bladder. Both acute and chronic treatment normalised renal vascular resistance, although the effect on blood pressure was more marked after chronic than after acute treatment. Although acute treatment with S5590 increased glomerular filtration rate and renal blood flow, chronic treatment did not affect these parameters. Diuresis and natriuresis were only slightly modified and the results suggest a marked renal vasodilatation. In conclusion, the maintenance of renal function after chronic treatment, in a setting of normalisation of arterial pressure, suggest that such a combined treatment may exert marked renal functional protective effects in hypertension.

[Biological factors influencing response to diuretics in patients with cirrhosis and ascites]

PURPOSES

To examine the biological factors influencing response to diuretics in patients with cirrhosis and ascites.

METHODS

Sixty-nine patients were evaluated. Patients were classified into 3 groups: group 1: "good responders" (responding to spironolactone 200 mg/day), group 2: "bad responders" (responding to spironolactone doses above 200 mg/day or requiring addition of furosemide), and group 3: "non-responders" (not responding to spironolactone 400 mg/day and furosemide 160 mg/day).

RESULTS

There were 30 patients in group 1, 24 in group 2 and 15 in group 3. The degree of activation of the renin-aldosterone and sympathetic system in group 2 was significantly higher than in group 1 and lower than in group 3. Natriuresis in group 2 (11 +/- 0.7 mEq/24h) was significantly below group 1 (20 +/- 2 mEq/24h) and above group 3 (5 +/- 0.6 mEq/24h).

CONCLUSIONS

In patients with cirrhosis and ascites, the degree of activation of the renin-aldosterone and sympathetic nervous system influences diuretic response of ascites and is estimated by measured baseline natriuresis.

Cholesterol regulates membrane binding and aggregation by annexin 2 at submicromolar Ca(2+) concentration

Annexin 2 is a member of the annexin family which has been implicated in calcium-regulated exocytosis. This contention is largely based on Ca(2+)-dependent binding of the protein to anionic phospholipids. However, annexin 2 was shown to be associated with chromaffin granules in the presence of EGTA. A fraction of this bound annexin 2 was released by methyl-beta-cyclodextrin, a reagent which depletes cholesterol from membranes. Restoration of the cholesterol content of chromaffin granule membranes with cholesterol/methyl-beta-cyclodextrin complexes restored the Ca(2+)-independent binding of annexin 2. The binding of both, monomeric and tetrameric forms of annexin 2 was also tested on liposomes of different composition. In the absence of Ca(2+), annexin 2, especially in its tetrameric form, bound to liposomes containing phosphatidylserine, and the addition of cholesterol to these liposomes increased the binding. Consistent with this observation, liposomes containing phosphatidylserine and cholesterol were aggregated by the tetrameric form of annexin 2 at submicromolar Ca(2+) concentrations. These results indicate that the lipid composition of membranes, and especially their cholesterol content, is important in the control of the subcellular localization of annexin 2 in resting cells, at low Ca(2+) concentration. Annexin 2 might be associated with membrane domains enriched in phosphatidylserine and cholesterol.

[Diagnosis and treatment of gastroesophageal reflux in the adult: guidelines recommended by French and Belgian consensus]

Usual gastroesophageal reflux (GER) presentations are heartburn and acid regurgitation. The prevalence in occidental population ranges from 5 to 45% according to symptoms frequency. Oesophagitis is observed in 30 to 50% of examined patients and only erosive and ulcerative lesions must be considered. Distinction is made between non-severe oesophagitis (isolated loss of substance), severe oesophagitis (circonferential loss of substance) and complicated oesophagitis (stenosis, ulcerations, brachyoesophagus). 24-hour pH-monitoring analyses reflux duration and relations between symptoms and reflux specially in unusual extraoesophageal presentations. Symptoms and quality of life are the main criteria for staging. In few patients, oesophagitis is severe. Complications (stenosis, ulcerations, bleeding, endobrachyoesophagus) are observed in 10 to 15% of cases. Endobrachyoesophagus with intestinal metaplasia is a risk for neoplasia. The consensus conference proposes this initial therapeutic strategy. In cases of time-spaced symptoms: antiacids, alginic acid or low doses of anti-H2 with life style changes. In cases of typical frequent symptoms, in patients younger than 50 years: 4-weeks treatment with half dosed proton pump inhibitors (PPI) or standard doses of anti-H2 or prokinetics. Nowadays, the majority of the experts propose empiric full-dose treatment. This attitude is more logical as total symptoms suppression with full dose PPI brings positive clues for exact GOR diagnostic without endoscopy. In patients older than 50 years or with alarming symptoms (weight loss, dysplagia, bleeding, anemia): endoscopy must be performed. Patients with non severe oesophagitis: PPI without checking endoscopy. In patients with severe or complicated oesophagitis: 8-weeks treatment following by endoscopy; in non relieved patients: doses are increased. In cases of extraoesophageal presentations: standard PPI treatment during 4 to 8 weeks if GER is well established. In long term strategy, if recidives are rare: intermittent treatment. In early and frequent recidives: long term adapted PPI or surgery. Stenosis are treated by PPI, pneumatic dilatation or surgery if unsuccessful. Brachyoesophagus must be checked by endoscopy every 2 years (malignancy risk).

N-Terminal domain of annexin 2 regulates Ca(2+)-dependent membrane aggregation by the core domain: a site directed mutagenesis study

Annexin 2 binds and aggregates biological membranes in a Ca(2+)-dependent manner. This protein exists as a monomer (p36) or as a heterotetramer (p90) in which two p36 chains are associated with a dimer of p11, a member of the S100 protein family. Protein kinase C phosphorylates the protein at the level of the N-terminal tail on serines 11 and 25, thereby modifying its oligomeric structure and its properties of membrane aggregation. To analyze these effects, the properties of a series of mutants in which serines 11 and 25 were replaced by alanine and/or glutamic acid were investigated. The affinity for p11 light chain was decreased in the S11E mutants. Glutamic acid residues in positions 11 or 25 did not change membrane binding, either in the tetrameric or in the monomeric form. On the other hand, these mutations affected the aggregation properties of the two forms. For the tetramer, the aggregation efficiency was decreased but not the Ca(2+) sensitivity, whereas the latter was affected in the case of the monomer. The effects were stronger in the S11E mutants, and they were cumulative in the double mutant. They suggest a different conformation of the N-terminal domain in the mutants (and in the phosphorylated protein), a hypothesis which is supported by proteolysis experiments. This conformational change would affect aggregation by the monomer through a dimerization step.

Biochemical characterization of Rab3-GTPase-activating protein reveals a mechanism similar to that of Ras-GAP

Small G proteins of the Rab family are regulators of intracellular vesicle traffic. Their intrinsic rate of GTP hydrolysis is very low but is enhanced by specific GTPase-activating proteins (GAPs) that switch G proteins to their inactive form. We have characterized the activity of recombinant Rab3-GAP on Rab3A in solution. The K(m) and K(d) values (75 microm) indicate a low affinity of Rab3-GAP for its substrate. The affinity is higher for the transition state analog Rab3A:GDP:AlF(x) (15 microm). The k(cat) (1 s(-)(1)) is within the range of values reported for other GAPs. A mutation in the switch I region of Rab3A disrupted the interaction with Rab3-GAP. Furthermore, Rabphilin, a putative target of Rab3, inhibited the activity of Rab3-GAP on Rab3. Therefore, the Rab3-GAP-binding site involves the switch I region of Rab3 and overlaps with the Rabphilin-binding domain. Substitution of a single arginine residue (Arg-728) of Rab3-GAP disrupted its catalytic activity but not its interaction with Rab3A. We propose that Rab3-GAP, like Ras- and Rho-GAPs, stabilizes the transition state of Rab3 and provides a critical arginine residue to accelerate the GTPase reaction.

Constitutive phosphorylation of the vesicular inhibitory amino acid transporter in rat central nervous system

gamma-Aminobutyric acid (GABA) and glycine are stored into synaptic vesicles by a recently identified vesicular inhibitory amino acid transporter [VIAAT, also called vesicular GABA transporter (VGAT)]. Immunoblotting analysis revealed that rat brain VIAAT migrated as a doublet during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with a predominant slower band in all areas examined except olfactory bulb and retina. The slower band corresponded to a phosphorylated form of VIAAT as it was converted to the faster one by treating brain homogenates with alkaline phosphatase or with an endogenous phosphatase identified as type 2A protein-serine/threonine phosphatase using okadaic acid. In contrast, the recombinant protein expressed in COS-7 or PC12 cells co-migrated with the faster band of the brain doublet and was insensitive to alkaline phosphatase. To investigate the influence of VIAAT phosphorylation on vesicular neurotransmitter loading, purified synaptic vesicles were treated with alkaline phosphatase and assayed for amino acid uptake. However, neither GABA nor glycine uptake was affected by VIAAT phosphorylation. These results indicate that VIAAT is constitutively phosphorylated on cytosolic serine or threonine residues in most, but not all, regions of the rat brain. This phosphorylation does not regulate the vesicular loading of GABA or glycine, suggesting that it is involved at other stages of the synaptic vesicle life cycle.

Selective endothelin-A versus combined endothelin-A/endothelin-B receptor blockade in rat chronic heart failure

BACKGROUND

The relative efficacy of endothelin-A (ET(A)) receptor blockade versus combined ET(A)-ET(B) receptor blockade in chronic heart failure (CHF) is still largely unknown.

METHODS AND RESULTS

We compared, in a rat model of CHF (coronary ligation), the hemodynamic and structural effects of 1 month of treatment with the ET(A) antagonist ABT-627 (5 mg x kg(-1) x d(-1)), the ET(B) antagonist A-192621 (30 mg x kg(-1) x d(-1)) or a combination of the 2 drugs. Doses were chosen for their capacity to block the pressor response to ET-1 (for ET(A) blockade) or the depressor responses to sarafotoxin S6c or ET-1 (for ET(B) blockade). ET(A) and combined ET(A)-ET(B) blockade reduced systolic blood pressure to the same extent, whereas ET(B) blockade had no effect. In contrast, only combined ET(A)-ET(B) blockade significantly reduced heart rate. Both ET(A) and combined ET(A)-ET(B) blockade, but not ET(B) blockade alone, increased left ventricular (LV) fractional shortening and wall thickening and reduced LV end-diastolic pressure, as well as LV end-diastolic and end-systolic volumes. However, all treatments (including ET(B) blockade) decreased LV collagen accumulation.

CONCLUSIONS

The chronic blockade of both ET(A) and ET(B) receptors improved systemic hemodynamics, as well as LV function and remodeling, to the same extent as ET(A) receptor blockade alone. However, only combined ET(A)-ET(B) receptor blockade decreased heart rate. Whether this differential effect on heart rate affects the long-term outcome after treatment with ET(A) or mixed ET(A)-ET(B) antagonists in CHF remains to be determined.

Improvement of endothelial function by chronic angiotensin-converting enzyme inhibition in heart failure : role of nitric oxide, prostanoids, oxidant stress, and bradykinin

BACKGROUND-Chronic heart failure (CHF) impairs the endothelium-dependent, flow-mediated dilation (FMD) of small arteries. However, whether chronic angiotensin-converting enzyme (ACE) inhibition affects the impairment of FMD in CHF is unknown. We investigated the effects of long-term ACE inhibition on the FMD of peripheral arteries in rats with CHF and the mechanism(s) involved. METHODS AND RESULTS-FMD was assessed in isolated, perfused gracilis muscle arteries from sham-operated, and untreated or ACE inhibitor-treated (perindopril 2 mg. kg(-1). day(-1) for 10 weeks) rats with CHF (coronary artery ligation). The role of nitric oxide (NO), prostaglandins, and free radicals was assessed by pretreating the vessels with the NO synthase inhibitor N(W)-nitro-L-arginine, the cyclooxygenase inhibitor diclofenac, or the free radical scavenger N-2-mercaptopropionyl-glycine (MPG). Endothelial NO synthase mRNA expression was determined by reverse transcriptase polymerase chain reaction. In animals with hemodynamic and echographic signs of CHF, FMD was converted into vasoconstriction, and this was prevented by ACE inhibition. FMD of arteries from sham-operated or ACE inhibitor-treated CHF rats was abolished by N(W)-nitro-L-arginine. In untreated CHF rats, FMD was increased by diclofenac and MPG. In contrast, in arteries from ACE inhibitor-treated rats, neither diclofenac nor MPG affected FMD. In parallel, ACE inhibition prevented the reduction of endothelial NO synthase mRNA by CHF. CONCLUSIONS-In CHF, ACE inhibition normalized NO-dependent dilatation and suppressed the production of vasoconstrictor prostanoid(s), resulting in improved FMD. The improvement of FMD might contribute to the beneficial effects of ACE inhibition during CHF.

Increased endothelium--monocyte interactions in salt-sensitive hypertension: effect of L-arginine

Although adhesion of monocytes to endothelial cells is considered as one of the initial factors leading in the long term to the development of atherosclerosis, the effects of hypertension on monocyte-endothelial cell interactions are still largely unknown. Thus we evaluated whether hypertension affects adhesion of monocytes on rat carotid endothelium, and whether this adhesion may be modified by long-term treatment with L-arginine, the physiologic precursor of nitric oxide (NO). Hypertension was induced in Dahl rats using a sodium-rich diet (8%), in the absence or the presence of L-arginine (1.25 g/L in drinking water). After 1 month, the carotid arteries were isolated, opened longitudinally, and incubated in the presence of 2 x 10(6) monocytes previously rendered fluorescent by incubation with tetramethyl rhodamine isothiocyanate (TRITC), and adherent cells were counted under fluorescence microscopy. In parallel, the production of NO was evaluated in vitro in isolated aorta and isolated hearts. Hypertension markedly increased adhesion of monocytes on carotid endothelium, and this was reduced by L-arginine. Hypertension also reduced an index of NO release at the level of the aorta and the coronary circulation. This impaired release of NO was partially prevented by L-arginine. Thus hypertension was associated with an increased adhesion of monocytes, which is probably due at least in part to a decreased production of NO. The increased adhesion was partly reduced by L-arginine, possibly secondary to an increased production of NO. Such an increased adhesion of monocytes may contribute the increased cardiovascular risk in hypertension.

Vesicular monoamine transporter 2 as a marker of gastric enterochromaffin-like cell tumors

The vesicular monoamine transporter 2 (VMAT2) facilitates the ATP-dependent accumulation of biogenic amine inside the secretory granules of endocrine cells and neurons and was demonstrated in the histamine-producing enterochromaffin-like (ECL) cells of the stomach. In the present investigation, VMAT2 immunohistochemistry was tested in 85 endocrine tumors, of which 60 were well differentiated gastrointestinal and pancreatic growths, 5 poorly differentiated (neuro)endocrine carcinomas (PDEC) and 1 mixed PDEC/ECL cell carcinoma of the stomach, 12 pheochromocytomas/paragangliomas, 3 adrenocortical lesions, 2 parathyroid and 2 lung neuroendocrine tumors. Extensive and intense VMAT2 immunoreactivity was observed in 16 of 16 gastric ECL cell tumors, 6 of 6 adrenal pheochromocytomas, 2 of 2 chromaffin paragangliomas and in 3 of the 4 carotid body paragangliomas investigated. Rare VMAT2-positive cells were observed in 12 of 21 intestinal enterochromaffin (EC) cell tumors, in 9 of 11 pancreatic neuroendocrine tumors, and in the mixed PDEC/ ECL cell carcinoma of the stomach (differentiated cells only). No VMAT2 immunoreactivity was observed in five gastrin, four somatostatin and three enteroglucagon/peptideYY tumors of the gastrointestinal tract, in six gastric PDECs, in three adrenocortical growths, and two parathyroid and two lung neuroendocrine tumors. These data support VMAT2 immunohistochemistry as being a useful tool for the diagnosis of gastric ECL cell tumors, separating them from all other endocrine tumors arising in the gastroduodenal area i.e., gastrin, somatostatin, EC cell and PDEC tumors, all of which proved essentially negative.

Chandra X-Ray Detection of the Radio Hot Spots of 3C 295

An observation of the radio galaxy 3C 295 during the calibration phase of the Chandra X-Ray Observatory reveals X-ray emission from the core of the galaxy, from each of the two prominent radio hot spots, and from the previously known cluster gas. We discuss the possible emission processes for the hot spots and argue that a synchrotron self-Compton (SSC) model is preferred for most or all of the observed X-ray emission. SSC models with near-equipartition fields thus explain the X-ray emission from the hot spots in the two highest surface brightness FR II radio galaxies, Cygnus A and 3C 295. This lends weight to the assumption of equipartition and suggests that relativistic protons do not dominate the particle energy density.

Molecular dissection of regulated secretory pathways in human gastric enterochromaffin-like cells: an immunohistochemical analysis

Enterochromaffin-like (ECL) cells regulate gastric acid secretion through vesicular release of histamine. Until now, the molecular machinery of human ECL cells involved in the formation and release of vesicles is largely unknown. We analyzed tissue samples obtained from normal human gastric mucosa (n=4) and ECLomas (n=5) immunohistochemically using the APAAP method or double immunofluorescence confocal laser microscopy. Human pheochromocytomas (n=5) were investigated in parallel and compared to ECL cells. Secretory pathways were characterized using antibodies specific for marker proteins of large dense-core vesicles (LDCVs; islet cell antigen 512, chromogranin A, pancreastatin, and vesicular monoamine transporter 2) and small synaptic vesicle (SSV) analogues (synaptophysin). Tissues were also analyzed for expression of the peptide hormone processing enzymes, carboxypeptidase E and prohormone convertase 1, as well as the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, 25-kDa synaptosome-associated protein (SNAP25), syntaxin, and synaptobrevin. Immunoreactivity for markers of LDCVs and SSV analogues were detected in normal ECL cells and ECLomas. Both tissues also showed expression of carboxypeptidase E and prohormone convertase 1. Analysis of vesicular SNARE (v-SNARE) and target membrane SNARE (t-SNARE) proteins revealed the presence of SNAP25, syntaxin, and synaptobrevin in normal and neoplastic ECL cells. Our data suggest that ECL cells possess the two vesicle types of regulated neuroendocrine secretory pathways, LDCVs and SSV analogues. Since ECL cells also contain typical SNARE proteins, the molecular machinery underlying secretory processes in this cell type appears to be identical to the secretory apparatus of neuroendocrine cells and neurons. In addition, our findings suggest that the secretory apparatus of ECL cells is maintained during neoplastic transformation.

Exercise improves flow-mediated vasodilatation of skeletal muscle arteries in rats with chronic heart failure. Role of nitric oxide, prostanoids, and oxidant stress

BACKGROUND

Flow-mediated dilatation (FMD) of the peripheral arteries may be impaired in chronic heart failure (CHF), and this could contribute to the increased peripheral resistance and exercise intolerance that occur with this disease. Physical exercise improves the FMD of large conduit arteries in CHF, but whether a similar impairment also occurs in smaller arteries is unknown. The mechanisms of the changes in FMD after CHF or exercise are also unknown.

METHODS AND RESULTS

FMD was assessed in isolated, perfused, and preconstricted gracilis muscle arteries from sham-operated rats or CHF rats (coronary artery ligation) who were either sedentary or exercised (30-minute swimming period twice a day for 10 weeks, starting 7 days after ligation). In animals with hemodynamic and echographic signs of CHF, FMD was abolished and converted into vasoconstriction (percent change in diameter after 370 microL/min flow: sham, 42+/-5%; CHF, -4+/-3%; P<0.05). Exercise partially restored FMD (18+/-3%; P<0.05 versus CHF). In sham rats, FMD was abolished by the nitric oxide-synthase inhibitor Nomega-nitro-L-arginine (L-NA) but unaffected by the cyclooxygenase inhibitor diclofenac or the free radical scavenger N-(2-mercaptopropionyl)-glycine (MPG). In arteries from sedentary CHF rats, FMD was not modified by L-NA, but it was partially restored by diclofenac or MPG. In exercised CHF rats, FMD was abolished by L-NA and only moderately improved by diclofenac or MPG. Likewise, endothelial nitric oxide synthase mRNA expression (determined by reverse transcription polymerase chain reaction at the level of the gracilis muscle) was reduced by CHF, and this was prevented by exercise.

CONCLUSIONS

CHF abolishes the FMD of small arteries by impairing the nitric oxide pathway, increasing oxidant stress, and releasing a prostanoid-contracting factor. Exercise partially restores FMD by increasing expression of endothelial nitric oxide synthase and preventing the production of vasoconstrictor prostanoids and free radicals. Such restoration of FMD might contribute to the increase in exercise capacity after physical exercise in CHF.

Presence of the vesicular inhibitory amino acid transporter in GABAergic and glycinergic synaptic terminal boutons

The characterization of the Caenorhabditis elegans unc-47 gene recently allowed the identification of a mammalian (gamma)-amino butyric acid (GABA) transporter, presumed to be located in the synaptic vesicle membrane. In situ hybridization data in rat brain suggested that it might also take up glycine and thus represent a general Vesicular Inhibitory Amino Acid Transporter (VIAAT). In the present study, we have investigated the localization of VIAAT in neurons by using a polyclonal antibody raised against the hydrophilic N-terminal domain of the protein. Light microscopy and immunocytochemistry in primary cultures or tissue sections of the rat spinal cord revealed that VIAAT was localized in a subset (63-65%) of synaptophysin-immunoreactive terminal boutons; among the VIAAT-positive terminals around motoneuronal somata, 32.9% of them were also immunoreactive for GAD65, a marker of GABAergic presynaptic endings. Labelling was also found apposed to clusters positive for the glycine receptor or for its associated protein gephyrin. At the ultrastructural level, VIAAT immunoreactivity was restricted to presynaptic boutons exhibiting classical inhibitory features and, within the boutons, concentrated over synaptic vesicle clusters. Pre-embedding detection of VIAAT followed by post-embedding detection of GABA or glycine on serial sections of the spinal cord or cerebellar cortex indicated that VIAAT was present in glycine-, GABA- or GABA- and glycine-containing boutons. Taken together, these data further support the view of a common vesicular transporter for these two inhibitory transmitters, which would be responsible for their costorage in the same synaptic vesicle and subsequent corelease at mixed GABA-and-glycine synapses.

The isolated complex of the translocase of the outer membrane of mitochondria. Characterization of the cation-selective and voltage-gated preprotein-conducting pore

The complex of the translocase mitochondrial outer membrane (TOM), mediates recognition, unfolding, and translocation of preproteins. We have used a combination of biochemical and electrophysiological methods to study the properties of the preprotein-conducting pore of the purified TOM complex. The pore is cation-selective and voltage-gated. It shows three main conductance levels with characteristic slow and fast kinetics transitions to states of lower conductance following application of transmembrane voltages. These electrical properties distinguish it from the mitochondrial voltage-dependent anion channel (porin) and are identical to those of the previously described peptide-sensitive channel. Binding of antibodies to the C terminus of Tom40 on the intermembrane space side of the outer membrane modifies the channel properties and allows determination of the orientation of the channel within the lipid bilayer. Mitochondrial presequence peptides specifically interact with the pore and decrease the ion flow through the channel in a voltage-dependent manner. We propose that the presequence-induced closures of the pore are related to structural alterations of the TOM complex observed during the various stages of preprotein movement across the mitochondrial outer membrane.

Effects of early stress on adult affiliative behavior

The recently evolved mammalian species preservative behavior as opposed to the ancient self preservative behavior involves parental care, nursing, social interaction, pair bonding and mutual defense. Gonadal steroids together with oxytocin are critical for this affiliative, attachment behavior. When there is stressful loss of control, gonadotrophins are diminished, and the self preservative, fight-flight catecholamine coping response takes priority. It is suggested that self preservation is associated with left hemispheric brain function and that species preservation is associated with right hemispheric function. Stress during infancy that is severe enough to create insecure attachment has a dissociative effect, disrupting right hemispheric emotional functioning and species preservative behavior, and a permanent bias towards self preservation can become an adult trait. In such a person with impaired affiliation, corticoid responses may be deficient. The coronary type A behavior pattern common in our society exhibits some of this deficiency in species preservative activity.

Regulation of the Ca2+ sensitivity of exocytosis by Rab3a

Ca2+ ions trigger the release of hormones and neurotransmitters and contribute to making the secretory vesicles competent for fusion. Here, we present evidence for the involvement of the GTP-binding protein Rab3a in the sensitivity of the exocytotic process to internal [Ca2+]. The secretory activity of bovine adrenal chromaffin cells was elicited by Ca2+ dialysis through a patch-clamp pipette and assayed by monitoring changes in cell membrane capacitance. Microinjection of antisense oligonucleotides directed to rab3a mRNA increased the secretory activity observed at low (0.2-4 microM) [Ca2+], but did not change the maximal activity observed at 10 microM free [Ca2+]. Moreover, after a train of depolarizing stimuli, the secretory activity of antisense-injected cells dialyzed with 10 microM [Ca2+] was increased significantly compared with that of control cells. This result suggests that the activity of either Rab3a or its partners might change upon stimulation. We conclude that Rab3a, together with its partners, participates in the Ca2+ dependence of exocytosis and that its activity is modulated further in a stimulus-dependent manner. These findings should provide some clues to elucidate the role of Rab3a in synaptic plasticity.

Increased UDP-glucuronosyltransferase activity and decreased prostate specific antigen production by biochanin A in prostate cancer cells

Our laboratory has characterized androgen metabolism in an androgen-responsive prostate cancer cell line (LNCaP) and showed that these cells accumulated intracellular testosterone primarily as glucuronidated metabolites. Using a cell-free assay with testosterone as substrate, we showed that LNCaP had UDP-glucuronosyltransferase (UDPGT) activity. Because dietary factors, such as flavonoids in soy products, may reduce the risk for hormone-dependent cancers, we studied the effects of flavonoids on testosterone-UDPGT activity. LNCaP cells were exposed to selected flavonoids for up to 6 days. The increase in UDPGT-specific activity was linear over this period. Of the compounds tested, biochanin A was the most potent, with increased activity at concentration range 0.5-50 microM. Activities were linear for time and protein and were unaffected by flavonoids added directly to the assay. Kinetics studies showed no change in Km for testosterone in the face of these large increases in specific activity. Cellular metabolism of testosterone reflected the increase in enzyme activity. Intact cells treated with biochanin A produced testosterone-glucuronide from testosterone at twice the rate of controls. The steroid form of the UDPGT transcript was expressed in LNCaP cells and was enhanced in biochanin A-treated LNCaP cells. Additionally, biochanin A markedly decreased prostate specific antigen (PSA) level against the effect of testosterone on PSA production. Biochanin A significantly decreased the testosterone-stimulated release of PSA, presumably because biochanin A increased UDPGT and increased the intracellular glucuronidation of testosterone. These studies suggest that the modulation of hormone metabolism by dietary factors may be important in the prevention and treatment of prostate cancer.

Calcium-dependent regulation of rab3 in short-term plasticity

The Rab3 proteins are monomeric GTP-binding proteins associated with secretory vesicles. In their active GTP-bound state, Rab3 proteins are involved in the regulation of hormone secretion and neurotransmitter release. This action is thought to involve specific effectors, including two Ca2+-binding proteins, Rabphilin and Rim. Rab3 acts late in the exocytotic process, in a cell domain in which the intracellular Ca2+ concentration is susceptible to rapid changes. Therefore, we examined the possible Ca2+-dependency of the regulatory action of GTP-bound Rab3 and wild-type Rab3 on neuroexocytosis at identified cholinergic synapses in Aplysia californica. The effects of recombinant GTPase-deficient Aplysia-Rab3 (apRab3-Q80L) or wild-type apRab3 were studied on evoked acetylcholine release. Intraneuronal application of apRab3-Q80L in identified neurons of the buccal ganglion of Aplysia led to inhibition of neurotransmission; wild-type apRab3 was less effective. Intracellular chelation of Ca2+ ions by EGTA greatly potentiated the inhibitory action of apRab3-Q80L. Train and paired-pulse facilitation, two Ca2+-dependent forms of short-term plasticity induced by a rise in intraterminal Ca2+ concentration, were increased after injection of apRab3-Q80L. This result suggests that the inhibition exerted by GTP-bound Rab3 on neuroexocytosis is reduced during transient augmentations of intracellular Ca2+ concentration. Therefore, a Ca2+-dependent modulation of GTP-bound Rab3 function may contribute to short-term plasticity.

Physical techniques for the study of exocytosis in isolated cells

Membrane traffic is an important aspect of cell biology which implies shuttle vesicles and multiple binding/fusion events. In spite of rapid progress at the biochemical level, the mechanism of fusion is still not understood. A detailed physical description of the phenomenon is possible at the level of the plasma membrane where secretory vesicles fuse with the cell membrane, a process known as exocytosis. This process is specially active in neurons (release of neurotransmitter) and in endocrine cells (release of hormones), where exocytosis is tightly regulated. Among the biophysical techniques developed, cell membrane capacitance measurements by the technique of patch-clamp and amperometry of the oxidizable secretory products have resulted in interesting information. These techniques have described the initial fusion pore, its fluctuations, the efflux of material through the pore and its irreversible expansion. Optical techniques, using bioluminescent and fluorescent probes are also in progress. For instance, the dye FM 1-43 binds to but is not translocated through biological membranes and it has been used to measure membrane surface, as done by capacitance measurement. Evanescent wave fluorescence microscopy has been recently introduced to analyse the behaviour of secretory granules in the vicinity of the plasma membrane.

The vesicular monoamine transporter: from chromaffin granule to brain

All characterized monoaminergic cells utilize the same transport system for the vesicular accumulation of monoamines prior to their release. This system operates in neuronal (catecholaminergic, serotoninergic or histaminergic) as well as in endocrine or neuroendocrine cells. For several decades, chromaffin granules from bovine adrenal medulla have been used as a model system, allowing progress in the understanding of the biophysics, the biochemistry and the pharmacology of the monoamine vesicular transporter. The transporters from rat, bovine and man have been cloned. Surprisingly, two genes encode different isoforms of the protein which are differentially expressed in monoaminergic systems. The conjunction of recombinant DNA techniques and expression in secretory or non-secretory cells with the large body of data obtained on the chromaffin granule transporter has allowed rapid progress in the study of the protein. But interestingly enough, this progress has open new possibilities in the study of biological problems, especially in the brain. The transporter is useful for the determination of the relationship between small and large dense core vesicles, for the understanding of the mechanism of the drugs such as 1-methyl-4-phenylpyridinium (MPP+), tetrabenazine or amphetamines, and as a marker in brain development. The possibility of regulations at the vesicular transporter level and of their effect on the quantum size has to be investigated. The vesicular monoamine transporter is also an important target for brain imaging.

Psychological and physiological responses to stress: the right hemisphere and the hypothalamo-pituitary-adrenal axis, an inquiry into problems of human bonding

In addition to repeated reexperiencing of the event, the delayed effects of severe psychological trauma, i.e., post traumatic stress disorder (PTSD), present a paradoxical mix of symptoms. There is enhancement of the self-preservative catecholamine states; anger and fear with a contrasting sense of meaninglessness and blunting of the emotional responses of the attachment behavior so critical for species preservation. Hormonally, there is a striking separation of the catecholamine response, which stays elevated and that of the hypothalamo-pituitary-adrenal (HPA) axis, which may remain at normal levels. Pathophysiologically, the reexperienceing of the trauma and the arousal may be associated with dysfunction of the locus coeruleus, amygdala and hippocampal systems. This article explores the consequences of an additional dysfunction: a dissociation of the hemispheres that appears to be responsible for the alexithymic avoidance and failure of the cortisol response that so often follow severe psychological trauma. There is neurophysiological evidence that the left the right hemispheres subserve different emotional sets that correspond to "control" and "appraisal," i.e., very approximately to the self and species preservative behavioral complexes, respectively. Several studies point to physiological dissociation of hemispheric functions during alexithymia. This raises the question: What has been lost if in this condition the right side no longer fully contributes to integrated cerebral function? Right hemispheric damaged children lose critical social skills and in adults the related sense of familiarity critical for bonding is lost. Such losses of social sensibilities may account for the lack of empathy and difficulties with bonding found in sociopathy and borderline personality: conditions now believed to result from repeated psychological trauma during development. On the other hand, systems that promote right hemispheric contributions provide solacing access to a "Higher Power." They also appear to protect against socially disordered behavior, substance abuse, the failure of the HPA axis and some aspects of the pathophysiology of chronic disease.

Cloning of a functional vesicular GABA and glycine transporter by screening of genome databases

The unc-47 locus of Caenorhabditis elegans has been suggested to encode a synaptic vesicle GABA transporter. Here we used hydropathy plot analysis to identify a candidate vesicular GABA transporter in genomic sequences derived from a region of the physical map comprising unc-47. A mouse homologue was identified and cloned from EST database information. In situ hybridization in rat brain revealed codistribution with both GABAergic and glycinergic neuronal markers. Moreover, expression in COS-7 and PC12 cells induced an intracellular, glycine-sensitive GABA uptake activity. These observations, consistent with previous data on GABA and glycine uptake by synaptic vesicles, demonstrate that the mouse clone encodes a vesicular inhibitory amino acid transporter.