Krzysztof Brzozowski

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan

Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.

Superselective renal artery embolization in the treatment of iatrogenic bleeding into the urinary tract.

Background The aim of this study was to evaluate the efficacy of superselective renal artery embolization in patients with bleeding into the urinary system. Material/Methods From 2007 to 2012, 20 patients were treated with superselective renal artery embolization for bleeding after percutaneous nephrolithotomy (PCNL), nephron-sparing surgery (NSS), including 1 patient with AVF after PCNL. During the procedure, embolization material was injected through a microcatheter to stop the bleeding. Embolization materials included a mixture of cyanoacrylate and lipiodol, embolization coils, and Spongostan. Clinical evaluation included remission of hematuria and normalization of blood morphotic elements. Results The cause of bleeding into the urinary tract was damage to vessels (all cases): with coexisting false aneurism (8 cases); with coexisting arterio-venus fistula (1 case); and with coexisting intrarenal hematoma (3 cases). The bleeding occurred 2–5 days after PCNL and NSS, and 10 days after PCNL with AVF. The mean hematocrit level was 22%–24%. Technical success was achieved in 20 cases. Clinical success was achieved in 19 cases. One patient with hematuria after PCNL with AVF needed a second endovascular treatment to stop bleeding. Conclusions Superselective renal artery embolization is an effective procedure in the treatment of iatrogenic bleeding into the urinary tract after PCNL and NSS.

Perfluorocarboxylic acids in cell growth media and technologically treated waters: Determination with GC and GC–MS

The present paper reports on an analytical method for the routine analysis of perfluorinated carboxylic acids (PFCAs). A rapid method for the derivatization, extraction and determination of PFCAs was developed. Technological samples were extracted with ethyl acetate and the anilides obtained were determined by gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Residue levels in cell growth incubation media were determined by GC-FID. Confirmation analysis of PFCAs was carried out by GC-MS in selected ion monitoring (SIM) and total ion current (TIC) modes. The compounds were identified on the basis of retention time and comparison of primary and secondary ions. The results showed that this method provided a simple, rapid and sensitive way of analyzing PFCAs in different matrices.

Investigation of Serine-Proteinase-Catalyzed Peptide Splicing in Analogues of Sunflower Trypsin Inhibitor 1 (SFTI-1)

Serine‐proteinase‐catalyzed peptide splicing was demonstrated in analogues of the trypsin inhibitor SFTI‐1: both single peptides and two‐peptide chains (C‐ and N‐terminal peptide chains linked by a disulfide bridge). In the second series, peptide splicing with catalytic amount of proteinase was observed only when formation of acyl–enzyme intermediate was preceded by hydrolysis of the substrate Lys–Ser peptide bond. Here we demonstrate that with an equimolar amount of the proteinase, splicing occurs in all the two‐peptide‐chain analogues. This conclusion was supported by high resolution crystal structures of selected analogues in complex with trypsin. We showed that the process followed a direct transpeptidation mechanism. Thus, the acyl–enzyme intermediate was formed and was immediately used for a new peptide bond formation; products associated with the hydrolysis of the acyl–enzyme were not observed. The peptide splicing was sequence‐ not structure‐specific.

Chemical structure of the O-polysaccharide isolated from Pectobacterium atrosepticum SCRI 1039.

The lipopolysaccharide (LPS) of the bacterium Pectobacterium atrosepticum SCRI 1039 was hydrolyzed and the products were separated. A study of the obtained O-polysaccharide by means of chemical methods, GLC, GLC-MS, and NMR spectroscopy allowed us to identify a branched polymer with a pentasaccharide repeating unit of the structure shown below, in which the fucose residue was partially O-acetylated at C-2, C-3 or C-4.

PEGylated substrates of NSP4 protease: A tool to study protease specificity.

Herein we present the synthesis of a novel type of peptidomimetics composed of repeating diaminopropionic acid residues modified with structurally diverse heterobifunctional polyethylene glycol chains (abbreviated as DAPEG). Based on the developed compounds, a library of fluorogenic substrates was synthesized. Further library deconvolution towards human neutrophil serine protease 4 (NSP4) yielded highly sensitive and selective internally quenched peptidomimetic substrates. In silico analysis of the obtained peptidomimetics revealed the presence of an interaction network with distant subsites located on the enzyme surface.

The use of 90Y-PET imaging in evaluation of 90Y-microspheres distribution in the liver: initial results.

BACKGROUND: Selective internal radiation therapy (SIRT) with 90Y-microspheres infusion into the hepatic artery is a novel method for palliative treatment of primary and metastatic liver cancer. The post-procedural 90Y dose estimation in the liver is very difficult because direct measurement of b particles is not possible with SPECT/CT. New methods are needed to assess the 90Y-microspheres liver distribution. In the present paper we evaluate the 90Y-PET for these purposes. MATERIALS AND METHODS: A GE Discovery ST PET/CT scanner with a copper ring protected the gantry was used for images acquisition. For SPECT/CT imaging, a GE Infinia VCHWK4 with HEPG collimators was used. The liver 90Y-microspheres (SIR-Spheres, SIRTEX, Australia) dose distribution after selective internal radiotherapy treatment was evaluated in three patients (9 lesions in total). The activity of 90Y-microspheres delivered into the liver ranged from 1.0 GBq to 2.2 GBq. The correlations between liver lesions detected with 90Y-PET, 99mTc-MAA and 90-bremsstrahlung were investigated and compared with CT images obtained before and after the procedure. RESULTS: The mean T/N ratio was 2.7 in 99mTc-MAA, 2.3 in 90Y-bremsstrahlung and 3.6 in 90Y-PET. The mean 90Y absorbed dose in tumor was 133 Gy, 112 Gy, and 187 Gy, respectively. The mean liver tissue radiation was 15.5 Gy. According to RECIST criteria, one PR (mCRC) and two SD were observed (mCRC and PC). Time to progression was 217 and 117 days in two patients with mCRC and 214 days in the patient with PC. CONCLUSIONS: 90Y-PET/CT images give crucial information regarding 90Y-microspheres distribution and dosimetry and may serve as a predictor of efficiency of radioembolisation.

Conformational studies of [Abu3, 11]-SFTI-1, an analogue of the trypsin inhibitor isolated from sunflower seeds

With only 14 amino acid residues, the trypsin inhibitor SFTI‐1 is the smallest naturally occurring serine proteinase inhibitor. It consists of two cyclic fragments (with head‐to‐tail cyclization and a disulfide bridge). In our previous paper, we showed that the removal of the disulfide bridge produced 2.4‐fold lower activity. Here, we present the total conformational analysis of the [Abu3, 11]‐SFTI‐1 analog by means of 2D NMR spectroscopy in conjunction with theoretical methods. The peptide was synthesized by Fmoc SPPS. It was cyclized with PyBop and DIPEA in DMF. The NMR studies were performed in DMSO‐d6 at 303 K. Conformations of the peptide studied were calculated by the following three approaches: distance geometry (DG), molecular dynamics (MD) and determination of the statistical weights of conformations. The first two algorithms use a CHARMM force field, whereas the last uses an ECEPP/3 force field. Our calculations resulted in three sets of conformers with 7, 9 and 6 representatives, respectively. All our results were compared with published ones. It was found that the peptide has an ill‐defined structure. Despite its conformational flexibility, the binding loop (3–11 fragment) displayed geometry similar to the corresponding fragments of the other SFTI‐1 analogs and to the inhibitor itself. Furthermore, the peptide bond between the Ile7 and Pro8 residues adopts cis geometry, which is essential for inhibitory activity. Copyright

Interventional radiology treatments for iatrogenic severe bleeding during percutaneous coronary interventions

Purpose Interventional cardiology and interventional radiology are separate medical disciplines in which intra-arterial contrast media are used. Interventional cardiology has resigned from many types of treatment techniques that are now used and developed in the field of interventional radiology. In the event of iatrogenic bleeding during coronary interventions, there is an urgent need to use safe and efficient rescue procedures that are as efficient as cardiosurgery but use simpler treatment options. Serious perforations require immediate endovascular interventions. Medical history may reveal risk factors for artery perforation. Medicines, location of artery perforation, and extent of bleeding are directly associated with the prognosis. Most often, arterial perforations are due to inappropriate wire manipulation or use of oversized balloons or cutting balloons. Prolonged, artery-occluding balloon inflation, covered stent implantation, and embolisation with different agents are among the available treatment options for artery ruptures. Material and methods A retrospective analysis was carried out among selected patients with iatrogenic vascular complications during procedures involving either coronary or non-coronary arteries. Results Only representative cases were selected and presented in the patient subsection. Conclusions Artery perforation during cardiac catheterisation can lead to dire consequences. To manage this complication, clinicians need pre-established procedures, adequate resources, and knowledge. Interventional radiology can be used as a salvage therapy in such cases.

The Predictive Value of SPECT/CT imaging in colorectal liver metastases response after 90Y-radioembolization

The aim of this study was to evaluate a modified method of calculating the 99mTc/90Y tumor-to-normal-liver uptake ratio (mT/N) based on SPECT/CT imaging, for use in predicting the overall response of colorectal liver tumors after radioembolization. A modified phantom-based method of tumor-to-normal-liver ratio calculation was proposed and assessed. In contrast to the traditional method based on data gathered from the whole tumor, gamma counts are collected only from a 2D region of interest delineated in the SPECT/CT section with the longest tumor diameter (as specified in RECIST 1.1). The modified tumor-to-normal-liver ratio (mT/N1) and 90Y predicted tumor absorbed dose (PAD) were obtained based on 99mTc-MAA SPECT/CT, and similarly the modified tumor-to-normal-liver ratio (mT/N2) and 90Y actual tumor absorbed dose (AAD) were calculated after 90Y-SPECT/CT. Tumor response was assessed on follow-up CTs. Using the newly proposed method, a total of 103 liver colorectal metastases in 21 patients who underwent radioembolization (between June 2009 and October 2015) were evaluated in pre-treatment CT scans and 99mTc-MAA-SPECT/CT scans and compared with post-treatment 90Y-SPECT/CT scans and follow-up CT scans. The results showed that the mT/N1 ratio (p = 0.012), PAD (p < 0.001) and AAD (p < 0.001) were predictors of tumor response after radioembolization. The time to progression was significantly lengthened for tumors with mT/N1 higher than 1.7 or PAD higher than 70 Gy. The risk of progression for tumors with mT/N1 lower than 1.7 or PAD below 70 Gy was significantly higher. The mT/N2 ratio had no significant correlation with treatment results. Conclusion The mT/N1 ratio, PAD, and AAD can be used as predictors of tumor response to SIRT treatment, and SPECT/CT imaging can be used for dosimetric assessment of radioembolization.