Synthesis and characterisation of PEG-peptide surfaces for proteolytic enzyme detection

Peptide surfaces were obtained by the covalent immobilisation of fluorescently labelled pentapeptides carboxyfluorescein–glycine–arginine–methionine–leucine–glycine, either directly or through a poly(ethylene glycol) (PEG) linker on modified silicon wafers. Each step during the preparation of the peptide surfaces was confirmed by several surface characterisation techniques. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy were used to determine the surface composition, the wafers philicity was measured by contact angle and atomic force microscopy was used to investigate the surface morphology. Exposure of the peptide surfaces to trypsin resulted in the release of a fluorescently labelled peptide product, which allowed the kinetics of the enzymatic reaction to be followed with the aid of fluorescence spectroscopy. The electrospray ionisation mass spectrometry analysis of the post-digestion solution confirmed that the pentapeptides attached to the solid support undergo specific trypsin hydrolysis at the C-terminus of the arginine residues. Detailed surface analyses before and after the enzyme action was performed using ToF-SIMS. Because of the limited accessibility of the short peptide directly attached to the surface, a quantitative yield of enzymatic hydrolysis was observed only in case when the peptide was bound through the PEG linker. The insertion of the PEG linker increased the number of immobilised peptides and the rate of enzymatic digestion which consequently improved the quality of the enzyme assays. The described approach may be used for different peptide sequences designed for other proteases. Figure Monitoring of trypsin hydrolysis on PEG-peptide surfac

INFLUENCE OF WELDING TECHNIQUES ON MICROSTRUCTURE AND HARDNESS OF STEEL JOINTS USED IN AUTOMOTIVE AIR CONDITIONERS

Austenitic steels belong to a group of special-purpose steels that are widely used in highly aggressive environments due to their enhanced anticorrosive behavior and high mechanical properties. The good formability and weldability of these materials has made them very popular in automotive AC systems. This study presents the results of hardness tests and microstructure observations on plasma- and laser-welded joints. The examined joints consisted of two different stainless steel components; i.e., a nipple made from corrosion-resistant AISI 304 steel and a corrugated hose made from 316L steel. Microplasma welding was carried out on a workstation equipped with an MSP-51 plasma supply system and a BY-100T positioner. The laser-welded joint was made on a numerically controlled workstation equipped with an Nd:YAG laser (without filler material) with 1 kW of maximum power; the rotational speed of the welded component was n = 4 rpm. Microstructural observations were performed using a scanning electron microscope and an optical microscope. Vickers hardness was measured with a hardness tester. The obtained results proved that both the microplasma- and laser-welded joints were free from any visible welding imperfections. In the micro areas of the austenitic steel weld, crystals of intercellular ferrite appeared against a background of austenite. The crystallization front (depending on the welding technology) was running from the fusion line towards the weld axis. The grain size depended on the distance from the fusion line

Effects of biofeedback training on esophageal peristalsis in amyotrophic lateral sclerosis patients with dysphagia

Esophageal manometry (EM) could serve as an objective method for the detection of esophageal peristalsis in patients with amyotrophic lateral sclerosis (ALS). In this group of patients, biofeedback training (BT) using the EM procedure is a promising method for the rehabilitation of swallowing function. A total of 20 ALS patients with clinical evidence of dysphagia and who met WFN criteria were recruited for this study. The standard transnasal EM with solid-state transducers was performed, and swallows with water and saliva were initiated in all subjects and repeated at 30-s intervals. The median upper esophageal contractile amplitude, duration, and velocity results during the wet and dry swallows were evaluated and compared in both the ALS and the control groups. In ALS patients, in contrast to the control, significant abnormalities in all EM parameters were recorded, which implies a specific pattern of esophageal peristalsis. Twelve months after BT, the body mass index (BMI) of ALS patients who underwent BT (ALSBT) was compared to the BMI of those who did not (ALS1)—compared to the ALS1 group, ALSBT patients showed a slightly smaller drop in BMI value. We presume that BT using EM can be a promising tool for the improvement of the swallowing mechanism in ALS patients

THE NUMERICAL INVESTIGATION OF THERMAL CYCLE OF LASER SURFACE HARDENING

Subassemblies of machines and devices must be characterized by appropriate exploitation features, especially in relation to the surface layer of cooperating surfaces. Structure and properties of these layers ensure appropriate resistance to abrasive, corrosive and fatigue wear and determine the operating life and failure-free cooperation of these components. Specific antiwear characteristics of surface layers can be obtained using many different manufacturing techniques. The current techniques include treatment with a concentrated energy beam, e.g. laser beam. The essence of the laser beam surface hardening process is the introduction of a sufficient amount of heat into the workpiece material as a result of the absorption of the laser radiation and the cooling of the surface as a result of heat conduction deep into the material (usually no additional cooling media are used for cooling). A necessary condition is an adequate heat capacity of the workpiece. The hardening process with concentrated energy beams does not require heating of the entire workpiece. The workpieces are only heated in the surface layer. A precisely defined and locally limited heat affected zone means that the amount of heat introduced into the material is very limited. Solving technical problems of surface hardening is often aided by numerical methods, among which the finite element method (FEM) is the most commonly used. In this study, FEM numerical models of the laser hardening process were developed. It was determined the heat capacity of the workpieces sufficient to achieve the required thermal cycle at the workpiece specific locations. It was also determined the influence of the heating path sequence and the time delay between them on the thermal cycles

Relevance of the poly(ethylene glycol) linkers in peptide surfaces for proteases assays

Poly(ethylene glycol)s (PEGs) with different lengths were used as linkers during the preparation of peptide surfaces for protease detection. In the first approach, the PEG monolayers were prepared using a "grafting to" method on 3-aminopropyltrietoxysilane (APTES)-modified silicon wafers. Protected peptides with a fluorescent marker were synthesized by Fmoc solid phase synthesis. The protected peptide structures enabled their site-specific immobilization onto the PEG surfaces. Alternatively, the PEG-peptide surface was obtained by immobilizing a PEG-peptide conjugate directly onto the modified silicon wafer. The surfaces (composition, grafting density, hydrophilicity, and roughness) were characterized by time-of-flight-secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), contact angle (CA), and atomic force microscopy (AFM). Introducing the PEG linker between the peptide and surface increased their resistance toward nonspecific protein adsorption. The peptide surfaces were examined as analytical platforms to study the action of trypsin as a representative protease. The products of the enzymatic hydrolysis were analyzed by fluorescence spectroscopy, electrospray ionization–mass spectrometry (ESI-MS), and ToF-SIMS. Conclusions about the optimal length of the PEG linker for the analytical application of PEG-peptide surfaces were drawn. This work demonstrates an effective synthetic procedure to obtain PEG-peptide surfaces as attractive platforms for the development of peptide microarrays

Vertigo as one of the symptoms of Lyme Disease

Objectives: The aim of the study was to evaluate the frequency of vertigo symptoms and potential labyrinth damage in patients with diagnosed Lyme disease (LD). LD can affect the vestibulocochlear nerve, leading to hearing loss and vertigo/dizziness. Material and Methods: The study included a group of 38 patients between the ages of 20 and 77, who were hospitalized due to vertigo/dizziness between 2018 and 2019. All of the patients underwent a detailed medical interview and an otolaryngological and neurological examination, including video electronystagmography (VENG), in addition to audiological and diagnostic tests. Additionally, ELISA and Western blot tests were performed to confirm the diagnosis of LD. Results: In 20 patients (53%), the Romberg trial was positive (p p = 0.011), and it mainly concerned high-frequency sounds (p = 0.014). Conclusion: Vertigo can be a symptom of LD. It is often associated with labyrinth and hearing-organ damage, which can imply that the inner ear or nerve VIII is dysfunctional in the course of this disease. Antibiotic therapy is effective in reducing otoneurological symptoms

Analiza związku między tolerancją wysiłku i jakością erekcji u poddanych treningowi mężczyzn z chorobą niedokrwienną serca i zaburzeniami erekcji

Background: In addition to a beneficial effect on exercise tolerance and an associated reduction of global cardiovascular risk, modificationof physical activity has a positive effect on the quality of life, reducing, among other things, the severity of erectile dysfunction (ED).Aim: The specific nature of sexual activity, which combines the need to maintain appropriate exercise tolerance and good erection quality, prompted us to evaluate the association between exercise tolerance and severity of ED in an intervention group of subjectswith ischaemic heart disease (IHD) and ED in the context of cardiac rehabilitation (CR).Methods: A total of 138 men treated invasively for IHD (including 99 treated with percutaneous coronary intervention and 39 treatedwith coronary artery bypass grafting) who scored 21 or less in the initial IIEF-5 test were investigated. Subjects were randomised intotwo groups. The study group included 103 subjects (mean age 62.07 ± 8.59 years) who were subjected to a CR cycle. The controlgroup included 35 subjects (mean age 61.43 ± 8.81 years) who were not subjected to any CR. All subjects filled out an initialand final IIEF-5 questionnaire and were evaluated twice with a treadmill exercise test. The CR cycle was carried out for a periodof 6 months and included interval endurance training on a cycle ergometer (three times a week) and general fitness exercises andresistance training (twice a week).Results: The CR cycle in the study group resulted in a statistically significant increase in exercise tolerance (7.15 ± 1.69 vs. 9.16 ± 1.84 METs,p < 0.05) and an increase in erection quality (12.51 ± 5.98 vs. 14.39 ± 6.82, p < 0.05) which was not observed in the controlgroup. A significant effect of age on a progressive decrease in exercise tolerance and erection quality was found in the study group. Exercise tolerance and erection quality were also negatively affected by hypertension and smoking. A significant correlation between exercise tolerance and erection quality prior to the rehabilitation cycle indicates better erection quality in patients with better effort tolerance. The improvement in exercise tolerance did not correlate significantly with initial exercise tolerance or age of the subjects. Incontrast, a significantly higher increase in erection quality was observed in younger subjects with the lowest baseline severity of ED.The relative increase in exercise tolerance in the group subjected to CR was significantly higher than the relative increase in erection quality but these two effects were not significantly correlated with each other.Conclusions: 1. In subjects with IHD and ED, erection quality is significantly correlated with exercise tolerance. 2. Exercise traininghad a positive effect on both exercise tolerance and erection quality but the size of these two effects was different and they ran independently of each other.Wstęp: Modyfikacja aktywności ruchowej, poza korzystnym wpływem na tolerancję wysiłku i związaną z tym redukcją globalnegoryzyka sercowo-naczyniowego, korzystnie wpływa na jakość życia, zmniejszając m.in. natężenie zaburzeń erekcji prącia (ED). Specyfikaaktywności seksualnej, która łączy w sobie konieczność zachowania odpowiedniej tolerancji wysiłku i dobrej jakości erekcjiprącia oraz obecność wspólnego dla tych dwóch elementów czynnika stymulującego zmianę ich natężenia, jakim jest prozdrowotna aktywność ruchowa, zainspirowała do przeprowadzenia analizy związku między tolerancją wysiłku i natężeniem ED w rehabilitowanejgrupie pacjentów z chorobą niedokrwienną serca (IHD) oraz ED.Cel: Celem pracy była ocena wpływu tolerancji wysiłku na jakość erekcji u chorych z IHD i ED oraz ocena modyfikacji obu tychprocesów wywołana przez cykl treningów kardiologicznych.Metody: Analizie poddano 138 mężczyzn leczonych inwazyjnie z powodu IHD (99 — przezskórna interwencja wieńcowa, 39 — pomostowanietętnic wieńcowych), którzy we wstępnym teście IIEF-5 uzyskali 21 i mniej punktów. Chorych losowo włączono do dwóch grup. W skład grupy badanej wchodziło 103 chorych (średni wiek 62,07 ± 8,59 roku), którzy zostali poddani cyklowi rehabilitacji kardiologicznej (CR). Grupę kontrolną stanowiło 35 chorych (średni wiek 61,43 ± 8,81 roku), którzy nie zostali poddani CR. Wszyscy chorzy wypełnili początkowy i końcowy test IIEF-5 oraz 2-krotnie zostali poddani testowi wysiłkowemu na bieżni ruchomej. Cykl treningów fizycznych realizowano w okresie 6 miesięcy i obejmował on interwałowe treningi wytrzymałościowe na cykloergometrze prowadzone 3 razy w tygodniu oraz ćwiczenia ogólnousprawniające i oporowe prowadzone 2 razy w tygodniu.Wyniki: Cykl CR w grupie badanej doprowadził do istotnej statystycznie poprawy tolerancji wysiłku (7,15 ± 1,69 vs. 9,16 ± 1,84 MET;p < 0,05) i poprawy jakości erekcji (12,51 ± 5,98 vs. 14,39 ± 6,82; p < 0,05), czego nie zaobserwowano w grupie kontrolnej. Analiza przeprowadzona w grupie badanej wskazuje na istotny wpływ wieku na postępujący spadek tolerancji wysiłku i pogarszanie się jakości erekcji, na którą negatywny wpływ wywierała także obecność u chorych nadciśnienia tętniczego i fakt palenia tytoniu. Istotna zależność między tolerancją wysiłku i jakością erekcji przed cyklem rehabilitacji wskazuje na lepszą jakość erekcji u pacjentówz lepszą tolerancją wysiłku. Przyrost tolerancji wysiłku nie wiązał się istotnie ani z początkową tolerancją wysiłku, ani z wiekiem chorych. W przeciwieństwie do tolerancji wysiłku znamiennie większa poprawa jakości erekcji miała miejsce u pacjentów młodszychi prezentujących wyjściowo najmniej natężone zaburzenia erekcji. Względny przyrost tolerancji wysiłku w grupie poddanej CR był istotnie większy od względnej poprawy jakości erekcji, przy czym obydwa procesy nie wiązały się ze sobą istotnie statystycznie.Wnioski: 1. U pacjentów z IHD i ED jakość erekcji wiąże się istotnie statystycznie z tolerancją wysiłku. 2. Trening pozytywnie modyfikował tolerancję wysiłku i jakość erekcji, przy czym obydwa procesy były istotnie różnie natężone i przebiegały niezależnie od siebie