Sealing of Vessels Larger Than 7 Millimeters Using Enseal in Porcine Aorta

Background:

The Enseal (Ethicon Endo-Surgery, Blue Ash, Ohio) tissue-sealing device has proven efficacy for ligation of vessels <7 mm in diameter, even with significant supraphysiologic bursting pressures. We aimed to evaluate the safety of Enseal in porcine vessels >7 mm.

Materials and Methods:

The lumbar aortas of pigs that were euthanized for unrelated procedures were harvested. A 5- to 6-cm segment of aorta was sealed using the Enseal device. The opposite end was attached to a pressure-testing device to measure pressures at leak or bursting. The bivariate Pearson correlation was used to determine the relationship between diameter and bursting pressure. One-way analysis of variance was used to determine differences between the groups of vessels on the basis of their diameter.

Results:

Ninety samples of 5-cm aorta segments were used to assess bursting pressure. The median diameter was 14 mm (range, 7–18) and bursting pressure was 85 mm Hg (range, 24–650). The Pearson test showed a negative correlation between vessel diameter and bursting pressure (P = .25). One-way analysis of variance did not show any significant difference between vessel diameters grouped by size (P = .517), and neither did the Scheffe post hoc test when comparing diameter with bursting pressure; 31% of specimens failed to seal.

Conclusions:

Bursting pressures are low and inconsistent after tissue sealing with the Enseal device in porcine vessels >7 mm. These vessels also demonstrated a higher rate of failure to seal. The histologic results of the aorta segments (ie, a low collagen-elastin ratio) may be the cause of the low bursting pressures.     

The concentration of adenine nucleotides in platelets of patients with primary chronic glomerulonephritis

Nephrotic syndrome (n.s.) is associated with numerous blood coagulation abnormalities and a marked predisposition to thromboembolism. Increased aggregation and activation of platelets in patients with glomerulonephritis (g.l.n. p.t.s.) may partly explain this status. The aim of this study was to measure the platelets adenine nucleotides concentration. The study was performed in 57 patients with a renal biopsy confirmed primary glomerulonephritis and 24 sex and age matched healthy volunteers which served as a control group. The patients were divided into two subgroups: subgroup I/A--36 patients with the symptoms of the nephrotic syndrome and subgroup I/B--21 patients with chronic glomerulonephritis and proteinuria but without the symptoms of nephrotic syndrome. Concentration of adenine nucleotides in platelets was measured using HPLC. In the subgroup I/A significantly lower levels of ATP, ADP and AMP concentrations in platelets were observed comparing to control subjects. Simultaneously significant correlation between both ATP and ADP concentration and plasma levels of albumin, total cholesterol, LDL-cholesterol, triglycerides and fibrinogen were found in g.l.n. p.t.s. SUMMARY AND CONCLUSIONS: 1. Significantly lower concentrations of adenine nucleotides in platelets of gln pts with the nephrotic syndrome may result from their activation. 2. Protein and lipid metabolism as well as fibrinogen seem to influence ATP and ADP concentrations in platelets of g.l.n. p.t.s.     

Chemo-Enzymatic Baeyer–Villiger Oxidation Facilitated with Lipases Immobilized in the Supported Ionic Liquid Phase

A novel method for chemo-enzymatic Baeyer–Villiger oxidation of cyclic ketones in the presence of supported ionic liquid-like phase biocatalyst was designed. In this work, multi-walled carbon nanotubes were applied as a support for ionic liquids which were anchored to nanotubes covalently by amide or imine bonds. Next, lipases B from Candida antarctica, Candida rugosa, or Aspergillus oryzae were immobilized on the prepared materials. The biocatalysts were characterized using various techniques, like thermogravimetry, IR spectroscopy, XPS, elemental analysis, and SEM-EDS microscopy. In the proposed approach, a biocatalyst consisting of a lipase as an active phase allowed the generation of peracid in situ from the corresponding precursor and a green oxidant–hydrogen peroxide. The activity and stability of the obtained biocatalysts in the model oxidation of 2-adamantanone were demonstrated. High conversion of substrate (92%) was achieved under favorable conditions (toluene: n-octanoic acid ratio 1:1 = v:v, 35% aq. H₂O₂ 2 eq., 0.080 g of biocatalyst per 1 mmol of ketone at 20 °C, reaction time 4 h) with four reaction cycles without a drop in its activity. Our ‘properties-by-design’ approach is distinguished by its short reaction time at low temperature and higher thermal stability in comparison with other biocatalysts presented in the literature reports.     

Applying the FMR Technique to Analyzing the Influence of Nitriding on the Magnetic Properties of Steel

This paper presents the relationship between the chemical composition and size of steel balls, the parameters of the nitriding process, and their magnetic properties, defined in this study by ferromagnetic resonance (FMR) and SQUID. Balls made from AISI 1010 and AISI 52100 steels, with diameters of 2.5 and 3 mm, respectively, were investigated. On samples made of AISI 1010 and AISI 52100 steel, single-phase layers of iron nitrides γ’ with a thickness of g_mp = 50 and 37 μm, respectively, were produced. Then, the samples were annealed at a temperature of 520 °C for 4 h in an inert atmosphere (N₂/Ar) at a pressure of 200 Pa. After the nitriding processes, steel balls were subjected to standard physical metallurgy and X-ray examinations. During annealing of nitrided layers with a two-phase layer of iron nitrides, at first, the transformation of the ε phase into the γ’ phase with the release of nitrogen into the atmosphere takes place. The FMR signals did not originate from isolated ions, but from more magnetically complex systems, e.g., Fe–Fe pairs or iron clusters, while the observed FMR line position is normally even lower and occurs for a magnetic induction below 200 mT. The fact that the magnetic centers did not contain mainly isolated Fe ions, additionally confirmed the abnormal increase in resonance signal intensity as a function of temperature, which is a behavior inconsistent with the Curie–Weiss law. The results obtained from measurements by the SQUID method, recording variations in magnetization as a function of temperature, confirm the untypical reinforcement of the magnetic conditions of the samples with the increase in temperature. For the samples tested, the magnetization was relatively weaker when the tests were conducted in a stronger magnetic field.