19 research outputs found
Inhibition effects in the partial oxidation of cyclohexane on polymer supported Co(II) catalysts
No full textPolymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II) nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect.Katalizatori na polimernom nosaču, sa različitim sadržajem metalnih jona, sintetisani su impregnacijom degaziranog nosača iz alkoholnog rastvora kobalt(II) nitrata. Makroretikularni kopolimer poli-4-vinilpriridina sa divinilbenzenom je korišćen kao nosač. Pripremljeni katalizatori su testirani u reakciji parcijalne oksidacije cikloheksana do smeše cikloheksanola i cikloheksanona. Katalitički testovi su izvedeni u laboratorijskom, autoklavu od nerđajućeg čelika, pod izotermalnim i neizotermalnim uslovima. Izotermalni eksperimenti su izvođeni na 170 °C tokom 120 min. U neizotermalnim eksperimentima korišćena je konstantna brzina grejanja od 0,3 °C/min, u intervalu 110 - 170 °C. Nelinearna analiza najmanjih kvadrata sa simpleks metodom optimizacije u numeričkom simulacijom u svakom iteracionom koraku, je korišćena za kinetičku karakterizaciju procesa u nestacionarnom režimu. Dobijene su prividne konstante brzine kao invarijantna karakteristika katalitičkog sistema. Uočeni su nelinearni efekti sadržaja metalnih jona na brzine reakcija i na odnose koncentracija proizvoda. Ovi efekti su pripisani složenoj interakciji reakcione sredine i heterogenog katalizatora, koja uključuje i inhibiciju
Salting-out thin-layer chromatography of several myorelaxants
No full textThe chromatographic behavior of five myorelaxant drugs has been studied under the conditions used for salting-out thin-layer chromatography (SOTLC) on cellulose and alumina. For this purpose, aqueous ammonium sulfate solutions of different concentration were used as mobile phases. It was established that hR(F) values always decreased in parallel to increasing salt concentrations. When cellulose was used as adsorbent, a linear relationship was observed between the R-M values and the ammonium sulfate content of the mobile phase. Regression data of the plots obtained were used to determine the lipophilicity parameters R-M(0) and C-0. Lipophilicity determined in this way correlated with calculated log P values
Early Bleeding After Laparoscopic Roux-en-Y Gastric Bypass: Incidence, Risk Factors, and Management — a 21-Year Experience
No full textPURPOSE: Morbidity and mortality associated with bariatric surgery are considered low. The aim of this study is to assess the incidence, clinical presentation, risk factors, and management of early postoperative bleeding (POB) after laparoscopic Roux-en-Y gastric by-pass (RYGB). MATERIALS AND METHODS: Retrospective analysis of prospectively collected data of consecutive patients who underwent RYGB in 2 expert bariatric centers between January 1999 and April 2020, with a common bariatric surgeon. RESULTS: A total of 2639 patients underwent RYGB and were included in the study. POB occurred in 72 patients (2.7%). Intraluminal bleeding (ILB) was present in 52 (72%) patients and extra-luminal bleeding (ELB) in 20 (28%) patients. POB took place within the first 3 postoperative days in 79% of patients. The most frequent symptom was tachycardia (63%). Abdominal pain was more regularly seen with ILB, compared to ELB (50% vs. 20%, respectively, p = 0.02). Male sex was an independent risk factor of POB on multivariate analysis (p < 0.01). LOS was significantly longer in patients who developed POB (8.3 vs. 3.8 days, p < 0.01). Management was conservative for most cases (68%). Eighteen patients with ILB (35%) and 5 patients with ELB (25%) required reoperation. One patient died from multiorgan failure after staple-line dehiscence of the excluded stomach (mortality 0.04%). CONCLUSION: The incidence of POB is low, yet it is the most frequent postoperative complication after RYGB. Most POB can be managed conservatively while surgical treatment is required for patients with hemodynamic instability or signs of intestinal obstruction due to an intraluminal clot. GRAPHICAL ABSTRACT: [Image: see text
Side-to-side magnet anastomosis system duodeno-ileostomy with sleeve gastrectomy: early multi-center results
No full textIntroduction: Gastrointestinal anastomoses with classical sutures and/or metal staples have resulted in significant bleeding and leak rates. This multi-site study evaluated the feasibility, safety, and preliminary effectiveness of a novel linear magnetic compression anastomosis device, the Magnet System (MS), to form a side-to-side duodeno-ileostomy (DI) diversion for weight loss and type 2 diabetes (T2D) resolution. Methods: In patients with class II and III obesity (body mass index [BMI, kg/m2] ≥ 35.0– ≤ 50.0 with/without T2D [HbA1C > 6.5%]), two linear MS magnets were delivered endoscopically to the duodenum and ileum with laparoscopic assistance and aligned, initiating DI; sleeve gastrectomy (SG) was added. There were no bowel incisions or retained sutures/staples. Fused magnets were expelled naturally. Adverse events (AEs) were graded by Clavien-Dindo Classification (CDC). Results: Between November 22, 2021 and July 18, 2022, 24 patients (83.3% female, mean ± SEM weight 121.9 ± 3.3 kg, BMI 44.4 ± 0.8) in three centers underwent magnetic DI. Magnets were expelled at a median 48.5 days. Respective mean BMI, total weight loss, and excess weight loss at 6 months (n = 24): 32.0 ± 0.8, 28.1 ± 1.0%, and 66.2 ± 3.4%; at 12 months (n = 5), 29.3 ± 1.5, 34.0 ± 1.4%, and 80.2 ± 6.6%. Group mean respective mean HbA1C and glucose levels dropped to 1.1 ± 0.4% and 24.8 ± 6.6 mg/dL (6 months); 2.0 ± 1.1% and 53.8 ± 6.3 mg/dL (12 months). There were 0 device-related AEs, 3 procedure-related serious AEs. No anastomotic bleeding, leakage, stricture, or mortality. Conclusion: In a multi-center study, side-to-side Magnet System duodeno-ileostomy with SG in adults with class III obesity appeared feasible, safe, and effective for weight loss and T2D resolution in the short term.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Examination of the hydrophobicity of ACE inhibitors and their active metabolites by salting-out thin-layer chromatography
No full textThe behavior of five ACE inhibitors and their active degradation products in salting-out thin-layer chromatography (SO TLC) has been examined on silica gel, cellulose, and polyacrylonitrile (PAN) with aqueous ammonium sulfate solutions of different concentration as mobile phases. It was found that increasing the concentration of the salt in the mobile phase led to increased R-M values for all the substances. Linear relationships were established between salt concentration and R-M values and regression data of the plots obtained were used to determine the lipophilicity R-M(0) and C-0. Lipophilicity determined in this way was correlated with calculated log P values. For comparison of these results with chromatographic behavior in conventional RP TLC, the examined substances were subjected to thin-layer chromatography on RP-18 silica gel with methanol-water mobile phases
Estimation of the hydrophobicity of antimycotic compounds by planar chromatography
No full textThe retention behavior of bifonazole, clotrimazole, fenticonazole, fluconazole, ketoconazole, miconazole, metronidazole, and itraconazole, widely used antimycotic drugs have been determined by TLC by use of the binary mobile phases acetone-n-hexane, methanol-toluene, and methyl ethyl ketone-toluene containing different amounts of organic modifier. Hydrophobicity was established from the linear relationships between the solute R-M values and the concentration of organic modifier. Calculated values of R-M(0) and C-0 were considered for application in QSAR studies of the antimycotics
Relationship between the bioavailability and molecular properties of angiotensin II receptor antagonists
No full textIn the present study, we investigated the relationships between several molecular properties and bioavailability data for seven of the most commonly prescribed angiotensin II receptor antagonists (also known as angiotensin II receptor blockers (ARBs) or sartans), candesartan, eprosartan, irbesartan, losartan, olmesartan, telmisartan and valsartan. The molecular descriptors of ARBs are:, aqueous solubility (logS values), polar surface area (PSA), molecular weight (Mw), volume value (Vol), lipophilicity (logP values) and the acidity descriptor (pK(a1)). The respective descriptors were calculated using four different software packages. The relevant bioavailability data were obtained from literature. Among calculated molecular descriptors, simple linear regression analysis showed the best correlation between bioavailability data and the lipophilicity descriptor, logP (R-2 = 0.568). Multiple linear regression established good correlations between bioavailability and the lipophilicity descriptor, logP, using the molecular weight, Mw, or the acidity descriptor, pK(a1), as an additional, independent variable (with R-2 = 0.661 and 0.682, respectively). Finally, excluding candesartan from the calculations resulted in a very good correlation (R-2 = 0.852) between the remaining ARB bioavailability and molecular descriptors MlogP and Mw as independent variables, determined by multiple linear regression
Assessment of the relationship between the molecular properties of calcium channel blockers and plasma protein binding data
No full textIn this study we investigated the relationship between the calcium channel blockers (CCBs), amlodipine, felodipine, isradipine, nicardipine, nifedipine, nimodipine, nisoldipine, verapamil and diltiazem, and their calculated molecular descriptors: polar surface area (PSA), molecular weight (Mw), volume value (Vol), aqueous solubility data (logS), lipophilicity (logP), acidity (pKa values) and plasma protein binding (PPB) data, obtained from relevant literature. The relationships between the computed molecular properties of selected CCBs and their PPB data were investigated by simple linear regression analysis that revealed very low correlations (R2 lt 0.35). When multiple linear regression (MLR) analysis was applied to investigate reliable correlations between the CCBs' calculated molecular descriptors and PPB data, the best correlations were found for the relationships between CCBs, and PPB data and lipophilicity, and with application of the molecular descriptor (Mw, Vol, or pKa) data as additional independent variables (R2=0.623; R2=0.741; R2=0.657, respectively), with an acceptable probability value (P lt 0.05), confirming that lipophilicity, together with other molecular properties, are essential for the drugs' PPB. We conclude that this could be considered as an additional in vitro approach for modeling CCBs
A PAMPA Assay as Fast Predictive Model of Passive Human Skin Permeability of New Synthesized Corticosteroid C-21 Esters
No full textThe permeation properties of twenty newly synthesized α-alkoxyalkanoyl and α-aryloxyalkanoyl C-21 esters of standard corticosteroids: Fluocinolone acetonide, dexamethasone, triamcinolone acetonide and hydrocortisone were established using a PAMPA assay (70% silicone oil and 30% isopropyl myristate). The data were compared with parent corticosteroids with addition of mometasone furoate and hydrocortisone acetate. All newly synthesized corticosteroid C-21 esters have effective permeability coefficients higher then -6, mostly followed with high values of retention factors and low permeation. The examined compounds were grouped through relationship between obtained retention factors and permeation parameters (groups I–III). The classification confirmed group I (membrane retentions as well as permeation lower then 30%) for all corticosteroid standards except mometasone furoate, a potent topical corticosteroid which, with high membrane retention (81%) and low permeation (7.7%) fits into group III. The largest number of new synthesized corticosteroids C-21 esters, among them all fluocinolone acetonide C-21 esters, have high membrane retentions (32.4%–86.5%) and low permeations (1.3%–27.1%), fitting in group III. The classification was related to previously obtained anti-inflammatory activity data for the fluocinolone acetonide C-21 esters series. According to the PAMPA results the new synthesized esters could be considered as potential new prodrugs with useful benefit/risk ratio
