Chitosan-based hydrogels for developing a small-diameter vascular graft: in vitro and in vivo evaluation.

AIMS: Vascular grafts made of synthetic polymers perform poorly in small-diameter applications (cardiac and peripheral bypass). Chitosan is a biocompatible natural polymer that can provide a novel biological scaffold for tissue engineering development. The goal of this study was to demonstrate the biocompatibility of a novel chitosan preparation in vitro and in vivo, and to assess its potential as a scaffold for vascular applications. METHODS AND RESULTS: A series of experiments of increasing complexity, ranging from in vitro biocompatibility and hemocompatibility tests to in vivo studies in small and large animals (rats and sheep), was performed to provide a comprehensive analysis of chitosan hydrogels' biological properties. In vitro studies established that: (i) chitosan supported human endothelial progenitor cells adhesion, proliferation and resistance to physiological shear stress; (ii) chitosan did not activate platelets, the complement system, or the intrinsic coagulation pathway. In vivo results showed: (iii) no resorption of chitosan and no chronic inflammation at 60 days in a rat heterotopic implantation model (magnetic resonance imaging and histology); (iv) no flow obstruction (Doppler ultrasound) and no thrombus formation (histology and scanning electron microscopy) at 2 h after a carotid arteriotomy repair with chitosan patches in sheep. Finally, two chitosan tubes were implanted as carotid interposition grafts for 3 days in sheep showing that chitosan was strong enough to be sutured, to withstand arterial pressure, and no flow obstruction was observed through this short period. CONCLUSION: Chitosan-based hydrogels displayed promising in vitro biocompatibility and hemocompatibility properties as well as in vivo short-term performance.

Proximal Occlusion of Medium-Sized Vessels with the Penumbra Occlusion Device: A Study of Safety and Efficacy.

PURPOSE: To retrospectively investigate the safety and efficacy of hybrid proximal coiling of various medium-sized vessels (4 to 8 mm) using the Penumbra Occlusion Device (POD). MATERIALS AND METHODS: From October 2014 to February 2016, 37 proximal embolizations were performed with PODs in 36 patients (mean age: 50.8, range: 10-86; 29 male, 7 female). Vessel occlusions were achieved under fluoroscopic guidance using a 2.7 French microcatheter. Among the 36 vessels targeted, 16 were splenic arteries, 11 renal arteries, 4 mesenteric arteries, 3 arteriovenous fistulae, 1 iliac artery, and 1 gonadal vein. Intermittent follow-up angiography was performed to assess the flow for final occlusion. Outcomes and complications were assessed by clinical and/or imaging follow-up. RESULTS: To produce proximal occlusion of the intended vessels, the POD was used alone in 19 embolizations (51.4 %). In 12 procedures (32.4 %), POD was used as a coil constrainer to secure the coil construct. In 6 procedures (16.2 %), additional embolic devices were used to achieve vessel occlusion after initial POD deployment. After a mean follow-up of 3.2 months, no POD migration was observed but two complications occurred (5.4 %): one post embolic syndrome and one extensive infarction with splenic abscess. CONCLUSION: The POD system allows safe and effective proximal embolization of medium-sized vessels in a variety of clinical settings.

Evidence for the use of drug eluting stents in below-the-knee lesions.

Peripheral arterial disease has become more and more present in daily practice, mostly due to the increase of cardiovascular risk factors, especially in below the knee (BTK) area in diabetic patients. Critical limb ischemia (CLI) is the most usual clinical presentation with a major amputation rate of 30%, mortality rate of 25%, and chronic pain of 20% at one year. Nowadays, endovascular treatment is usually the first choice, given the high comorbidity of those patients. Angioplasty and stenting in BTK lesions have already proven their efficacy in CLI treatment. However, BTK revascularization remains highly controversial in the treatment of intermittent claudication in TASC 2 recommendations. Restenosis being the major pitfall in BTK procedures, the use of drug-coated devices is one of the actual answers. We performed an extensive review of the literature over the last 15 years on the use of drug-eluting stents (DES) in BTK revascularization. DES has been compared to balloon angioplasty, in the ACHILLES trial, bare metal stents (BMS), in the DESTINY and YUKON trials, drug eluting balloons, in a trial guided by Siablis, and paclitaxel has even been compared to sirolimus in the PARADISE trial. In conclusion, DES is one of the solutions to the increase of BTK arteriopathy in CLI patients. Angiographic results are better, compared to BMS, in terms of primary patency, restenosis and TLR rates. However clinical results are missing. Treated lesions in the literature are short lesions. And DES is a metal balloon expandable stent with greater risks of compressions and stent fractures than nitinol self expandable stents, and such complications are known to increase post operative restenosis rates. Further reports are still needed on this matter.

Early-onset metabolic syndrome in prepubertal obese children and the possible role of alanine aminotransferase as marker of metabolic syndrome.

INTRODUCTION: Obesity is often associated with increased serum alanine aminotransferase (ALT), and elevation of ALT is a marker of non-alcoholic fatty liver disease which is caused in part by insulin resistance, the essential characteristic of metabolic syndrome (MS). We evaluated the prevalence of MS in prepubertal obese children and the usefulness of ALT as an MS marker. PATIENTS: 120 obese children (6.3 ± 1.6 years old) and 50 normal-weight controls (5.3 ± 2.0 years old) were included. Patients were classified as having MS if they met ≥ 3 of the following criteria: body mass index >97th percentile, triglycerides >95th percentile, high-density lipoprotein cholesterol <5th percentile, systolic (SBP) and/or diastolic (DBP) blood pressure >95th percentile, fasting blood glucose 100 mg/dl and/or impaired insulin sensitivity with homeostasis model assessment for insulin resistance >97.5th percentile. ALT levels were also evaluated. RESULTS: MS occurred in 16.6% of obese patients. Significant differences were present in body mass index (p < 0.001), SBP (p = 0.002) and DBP (p < 0.001) between non-MS and MS obese patients; laboratory data, except total cholesterol, were significantly different in the two groups. The strongest association with MS (as evaluated by the c-statistic) was found for insulin and homeostasis model assessment for insulin resistance (c = 0.92 and 0.91, respectively); also, DBP and SBP showed good discrimination ability (c = 0.73 and 0.72, respectively). ALT levels in the MS group were higher than in the non-MS group (p = 0.02) and associated with MS (p = 0.001; c = 0.69). CONCLUSION: MS is a consequence of obesity already in very young children. Also, pathological serum ALT levels were significantly correlated with MS and might be considered a marker for defining MS, though confirmation in a longitudinal study is called for.

Thyroid ultrasound in patients with Turner syndrome: influence of clinical and auxological parameters.

OBJECTIVES: To determine thyroid volume and structure by ultrasound (US) in patients with Turner syndrome (TS) compared to healthy controls; to evaluate the frequency and characteristics of autoimmune thyroid disease (ATD) and its association with clinical and auxological parameters. PATIENTS: 73 patients and 93 height-matched healthy female controls in the same age range were included in the study. RESULTS: Thirty-two TS patients (43.8%) presented ATD. They had a larger body mass index (BMI) and presented the 45,X karyotype more frequently than those without. They were older, with a higher prevalence of lymphoedema at birth and pterygium colli without statistical significance. Thyroid volume was 20% larger in the presence of ATD (p=0.037). A dyshomogeneous thyroid structure was observed in all patients with ATD and less frequently in those without (p=0.016). Dyshomogeneity in TS without ATD was also associated with older age (p<0.001), larger BMI (p=0.003) and larger thyroid volume (p=0.006). Six TS patients presented solitary thyroid nodules (5 benign nodules). We observed a significant interaction between diagnosis and height (p=0.035) and age (p=0.047), indicating that both age and height conditioned the observed differences in thyroid volume. CONCLUSIONS: Most TS patients presented ATD with a normal thyroid function or subclinical hypothyroidism, without goiter. Dyshomogeneous thyroid structure was also observed in TS patients without ATD. In TS, the evaluation of thyroid volume according to chronological age does not seem to be efficient because of a link between height and thyroid volume. The prevalence of nodular thyroid disease is similar to that observed in the general population.

Salvage treatment for venous aneurysm complicating vascular access arteriovenous fistula: use of an exoprosthesis to reinforce the vein after aneurysmorrhaphy.

OBJECTIVES: We report a new salvage technique for treating venous aneurysms (VAs) complicating vascular access arteriovenous fistula (AVF) using externally reinforced venous aneurysmorrhaphy. DESIGN: A retrospective study over a 20-month period from a single centre. PATIENTS: Patients presenting to the vascular surgery department, Bordeaux University Hospital for revision of a vascular access AVF were included. METHODS: Reinforced venous aneurysmorrhaphy consisted in removal of redundant vessel wall followed by reinforcement using an external prosthetic graft. Patency, diameter and flow were assessed by duplex ultrasound at 1, 6 and 12 months after salvage. RESULTS: Thirty-eight eligible patients were identified. Five were excluded because VA was associated with central vein stenosis; the remaining 33 underwent salvage. Indications were rapidly expanding or painful VA in seven cases; VA with frequent bleeding or damaged overlying skin in eight; VA in close relation to a stenosis in two; and VA associated with high-flow rate in 16. Cannulation was attempted after 30 days. Mean follow-up time was 12 S.D. 5 months (range: 4-22). Two repaired AVFs failed. Primary 1-year patency was 93%. No aneurysm or infection occurred. Reduction of high flow was successful in 12 of 16 patients. The remaining four required re-operation. CONCLUSIONS: Reinforced venous aneurysmorrhaphy is effective in controlling venous dilation and achieving patency. Reduction of high-flow rates was not always achieved. Further study is needed to evaluate long-term efficacy of this treatment.

Utility of breast ultrasonography in the diagnostic work-up of precocious puberty and proposal of a prognostic index for identifying girls with rapidly progressive central precocious puberty.

OBJECTIVE: To determine the utility of breast ultrasono- graphy in the diagnostic work-up of precocious puberty and to create a prognostic index for early differentiation between non/slowly progressive or transient forms of precocious puberty and rapidly progressive central precocious puberty. METHODS: We recruited consecutively 60 girls with precocious pubertal development. In all the girls we evaluated Tanner stage, basal and gonadotropin-releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, estradiol (E2) levels, and bone age, and performed pelvis and breast ultrasound examinations. Logistic regression models were fitted to identify possible diagnostic factors for rapidly progressive central precocious puberty and non/slowly progressive or transient forms. RESULTS: Ultrasound breast volume>or=0.85 cm3 was associated with rapidly progressive central precocious puberty (P=0.01). Uterine volume>or=5 cm3, LH peak>or=7 IU/L, presence of an endometrial echo, E2 levels>or=50 pmol/L and bone age>2 SD above expected were significantly associated with rapidly progressive central precocious puberty. A multivariate model including uterine volume, E2 level, bone age, presence of an endometrial echo and ultrasound breast volume revealed a strong ability to classify rapidly progressive forms. From this multivariate analysis a prognostic index for rapidly progressive central precocious puberty was defined. CONCLUSIONS: Ultrasound imaging allows better definition of the breast and the maturation stage than does use of Tanner's stages. Ultrasound breast volume>or=0.85 cm3 is an independent predicting factor of rapidly progressive central precocious puberty. A prognostic index that was created from a multivariate model including uterine volume, E2 level, presence of an endometrial echo, bone age and ultrasonographically determined breast volume, may help in the early differentiation between rapidly progressive central precocious puberty and non/slowly progressive or transient forms.

In vitro and in vivo pharmacology of synthetic olivetol- or resorcinol-derived cannabinoid receptor ligands.

BACKGROUND AND PURPOSE: We have previously reported the development of CB-25 and CB-52, two ligands of CB1 and CB2 cannabinoid receptors. We assessed here their functional activity. EXPERIMENTAL APPROACH: The effect of the two compounds on forskolin-induced cAMP formation in intact cells or GTP-gamma-S binding to cell membranes, and their action on nociception in vivo was determined. KEY RESULTS: CB-25 enhanced forskolin-induced cAMP formation in N18TG2 cells (EC50 approximately 20 nM, max. stimulation = 48%), behaving as an inverse CB1 agonist, but it stimulated GTP-gamma-S binding to mouse brain membranes, behaving as a partial CB1 agonist (EC50 =100 nM, max. stimulation = 48%). At human CB1 receptors, CB-25 inhibited cAMP formation in hCB1-CHO cells (EC50 = 1600 nM, max. inhibition = 68% of CP-55,940 effect). CB-52 inhibited forskolin-induced cAMP formation by N18TG2 cells (IC50 = 450 nM, max. inhibition = 40%) and hCB1-CHO cells (EC50 = 2600 nM, max. inhibition = 62% of CP-55,940 effect), and stimulated GTP-gamma-S binding to mouse brain membranes (EC50 = 11 nM, max. stimulation approximately 16%). Both CB-25 and CB-52 showed no activity in all assays of CB2-coupled functional activity and antagonized CP55940-induced stimulation of GTP-gamma-S binding to hCB2-CHO cell membranes. In vivo, both compounds, administered i.p., produced dose-dependent nociception in the plantar test carried out in healthy rats, and antagonised the anti-nociceptive effect of i.p. WIN55,212-2. In the formalin test in mice, however, the compounds counteracted both phases of formalin-induced nociception. CONCLUSIONS AND IMPLICATIONS: CB-25 and CB-52 behave in vitro mostly as CB1 partial agonists and CB2 neutral antagonists, whereas their activity in vivo might depend on the tonic activity of cannabinoid receptors.

Nuclear magnetic resonance for studying recognition processes between anandamide and cannabinoid receptors.

The understanding of the molecular basis of cannabinoid activity has greatly improved since the discovery of CB1 and CB2 receptors. In this paper, the ligand binding processes between the endogenous cannabimimetic ligand, anandamide (AEA), and the cannabinoid receptors from different parts of rat brain were studied by nuclear magnetic resonance spectroscopy. The NMR approach is based on the comparison of selective (R1(SE)) and non-selective (R1(NS)) proton spin-lattice relaxation rates of the ligand in the presence and absence of macromolecular receptors, as well as R1(NS) and R1(SE) temperature dependency analysis. From these studies, the ligand-receptor binding strength was evaluated on the basis of the calculation of the "affinity index". The derivation of the "affinity index" from chemical equilibrium kinetics for all systems allowed the comparison of the ability of anandamide to interact with cannabinoid receptors present in different brain sectors.

Synthesis, binding affinity and selectivity of new beta 1- and beta 2-adrenoceptor blockers.

The synthesis of a new series of sesamol derivatives with beta-adrenergic blocking activity is described. The affinity and selectivity of these compounds for beta 1- and beta 2-adrenoceptors were studied in comparison with those of ICI-118551 and propranolol. Some of the synthesized compounds show very good affinity for the beta 2-receptors of rat lung membranes and two of them provide interesting selectivity.

Structure-activity relationships in open ansa-chain rifamycin S derivatives as inhibitors of HIV-1 reverse transcriptase.

Three types of open ansa-chain rifamycin S derivatives have been prepared: derivatives with the ansa-chain open at C(29) and the original dihydrofuranone ring; derivatives with the ansa-chain open at C(29) and a furane ring; derivatives with the ansa-chain at open NH-C(15). Only derivatives of the first type are weak inhibitors of HIV-1 reverse transcriptase (IC50 ca.300 microM) while derivatives of the two other types are inactive. It has been hypothesized that the active derivatives inhibit the viral enzyme interacting through the groups C(14)H3, C(13)H3, and C(1)O at the same site as the well-known inhibitors TIBO and Nevirapine. In particular C(13)H3 must be unhindered and in an appropriate position out of the plane containing the chromophore-rings. The open ansa-chain seems to play the role of a lipophylic substituent.

Rapid analysis of somatostatin in pharmaceutical preparations by HPLC with a micropellicular reversed-phase column.

A rapid high-performance liquid chromatography method for the analysis of somatostatin in pharmaceutical preparations is described. A commercially available column packed with 2 microns spherical non-porous silica-based reversed-phase sorbent is used, along with a mobile phase consisting of acetonitrile and aqueous phosphoric acid, adjusted to pH 2.8 with sodium hydroxide. The effect of the organic modifier content and column temperature on the retention behaviour of somatostatin is reported. The method is found to be highly selective and specific, as indicated by the baseline separation of a mixture containing somatostatin and two analogue peptides, which differ from the analyte for one and two amino acids, respectively. Down to 10 ng of somatostatin can be detected and the detector response is linear over the concentration range from 4.14 to 20.75 micrograms ml-1. The application of this method to two commercial pharmaceutical formulations of somatostatin is found to give a mean percentage recovery from each of the two commercial samples, subjected to multiple injection analysis (n = 5), of 100.9% with a RSD of 0.92%, and 102.6% with a RSD of 1.56%, respectively.

Rifamycins as inhibitors of retroviral reverse transcriptase from M-MuLV, RAV-2, and HIV-1.

29 Rifamycins were tested for inhibition of Reverse Transcriptase (RT) as potential anti HIV drugs. Two purified commercial enzymes from M-MuLV and RAV-2 were used. Anti-RT activity was also measured on a crude lysate of HIV-1. The results show that some derivatives have interesting levels of activity on isolated M-MuLV and RAV-2 RTs, while they are less active on the RT in the crude HIV-1 lysate. The active derivatives include oximes and hydrazones, alkylaminoderivatives, open ansa-chain derivatives and derivatives carrying a modified nucleoside.

New 1,2,4-oxadiazole derivatives: synthesis and adrenergic receptors binding studies.

In order to obtain derivatives with simultaneous alpha- and beta-adrenergic blocking activity, compounds having the phenoxypropanolaminic structure of beta-adrenergic blockers have been synthesised, as well as 1,2,4-oxadiazole moiety, which could imitate the imidazolinic nucleus characteristic of drugs acting on alpha-adrenergic receptors. The synthesised compounds have been submitted to alpha and beta receptor binding assays. Some derivatives showed an alpha-adrenoceptor binding activity higher than labetalol and similar to prazosin, but with a poor beta-adrenoceptor binding activity.

Quinolinehydrazones as inhibitors of retroviral reverse transcriptase.

The inhibitory activity of a series of 2- and 4-quinolinehydrazones on retroviral reverse transcriptase has been studied on enzymes from M-MuLV, RAV-2, and on a crude lysate of HIV-1, assuming the first two enzymes as potential models of the third. The highest activity is mainly found in lipophilic, water soluble 4-quinolinehydrazones. The inhibitory activity of these compounds decreases in changing from the M-MuLV to the RAV-2, and HIV-1 enzymes, in this order.

[Quinolylhydrazones with potential antimicrobial and antiparasitic activity]. / Chinolilidrazoni a potenziale attività antimicrobica ed antiparassitaria.

Quinolinehydrazones prepared by condensation of hydrazinoquinolines with 1-phenyl-2,5-dimethyl-3-pyrrolcarboxaldehyde, 2-chloro-4-dimethylaminobenzaldehyde and 2,6-dichlorobenzaldehyde are described. All compounds were tested in vitro for antimicrobial activity, the results obtained are shown and discussed. The quinolinehydrazones of the 1-phenyl-2,5-dimethyl-3-pyrrolcarboxaldehyde were tested in vivo against Hymenolepis nana and Taenia taeniaeformis and proved inactive.

Chemical modifications of the aliphatic bridge of ansamycins. Synthesis and activity of 25-deacetoxy-25-epi-hydroxyrifamycin S.

Rifamycins are supposed to bind to, and inhibit the bacterial DNA-dependent RNA polymerase (DDRP) by the formation of hydrogen bonds through O (1), O (2), O (9), O (10). Therefore, with the aim of increasing the intrinsic activity of rifamycin S (1), the 25-deacetoxy-25-epi-hydroxyrifamycin S (8), was synthesized, which displays an additional hydroxyl available for the inhibiting interaction with the bacterial enzyme. The configuration and conformation of the new compound were as expected, but the biological evaluation did not confirm the hypothesis.