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Efficacy of immune checkpoint inhibitor therapy for advanced urothelial carcinoma in real-life clinical practice: results of a multicentric, retrospective study. Sci Rep 2023; 13:17378. [PMID: 37833455 PMCID: PMC10575904 DOI: 10.1038/s41598-023-44103-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Clinical trials revealed significant antitumor activity for immune checkpoint inhibitors (ICI) in metastatic urothelial carcinoma (mUC). Due to their strict eligibility criteria, clinical trials include selected patient cohorts, and thus do not necessarily represent real-world population outcomes. In this multicentric, retrospective study, we investigated real-world data to assess the effectiveness of pembrolizumab and atezolizumab and to evaluate the prognostic value of routinely available clinicopathological and laboratory parameters. Clinical and follow-up data from mUC patients who received ICIs (01/2017-12/2021) were evaluated. Overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and duration of response (DOR) were used as endpoints. Patients' (n = 210, n = 76 atezolizumab and 134 pembrolizumab) median OS and PFS were 13.6 and 5.9 months, respectively. Impaired ECOG-PS, the presence of visceral, liver or bone metastases, and hemoglobin levels were independently associated with poor OS and DCR. Furthermore, Bellmunt risk factors and the enhanced Bellmunt-CRP score were shown to be prognostic for OS, PFS and DCR. In conclusion, ICIs are effective treatments for a broad range of mUC patients. Our results confirmed the prognostic value of numerous risk factors and showed that Bellmunt risk scores can further be improved when adding CRP to the model.
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Comparative proteome and serum analysis identified FSCN1 as a marker of abiraterone resistance in castration-resistant prostate cancer. Prostate Cancer Prostatic Dis 2023:10.1038/s41391-023-00713-y. [PMID: 37634036 DOI: 10.1038/s41391-023-00713-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 07/14/2023] [Accepted: 08/03/2023] [Indexed: 08/28/2023]
Abstract
BACKGROUND Abiraterone (Abi) is an androgen receptor signaling inhibitor that significantly improves patients' life expectancy in metastatic prostate cancer (PCa). Despite its beneficial effects, many patients have baseline or acquired resistance against Abi. The aim of this study was to identify predictive serum biomarkers for Abi treatment. METHODS We performed a comparative proteome analysis on three Abi sensitive (LNCaPabl, LAPC4, DuCaP) and resistant (LNCaPabl-Abi, LAPC4-Abi, DuCaP-Abi) PCa cell lines using liquid chromatography tandem mass spectrometry (LC-MS/MS) technique. Two bioinformatic selection workflows were applied to select the most promising candidate serum markers. Serum levels of selected proteins were assessed in samples of 100 Abi-treated patients with metastatic castration-resistant disease (mCRPC) using ELISA. Moreover, FSCN1 serum concentrations were measured in samples of 69 Docetaxel (Doc) treated mCRPC patients. RESULTS Our proteome analysis identified 68 significantly, at least two-fold upregulated proteins in Abi resistant cells. Using two filtering workflows four proteins (AMACR, KLK2, FSCN1 and CTAG1A) were selected for ELISA analyses. We found high baseline FSCN1 serum levels to be significantly associated with poor survival in Abi-treated mCRPC patients. Moreover, the multivariable analysis revealed that higher ECOG status (>1) and high baseline FSCN1 serum levels (>10.22 ng/ml by ROC cut-off) were independently associated with worse survival in Abi-treated patients (p < 0.001 and p = 0.021, respectively). In contrast, no association was found between serum FSCN1 concentrations and overall survival in Doc-treated patients. CONCLUSIONS Our analysis identified baseline FSCN1 serum levels to be independently associated with poor survival of Abi-treated, but not Doc-treated mCRPC patients, suggesting a therapy specific prognostic value for FSCN1.
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Comprehensive Analysis of the Prognostic Value of Circulating MMP-7 Levels in Urothelial Carcinoma: A Combined Cohort Analysis, Systematic Review, and Meta-Analysis. Int J Mol Sci 2023; 24:ijms24097859. [PMID: 37175566 PMCID: PMC10178327 DOI: 10.3390/ijms24097859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/29/2023] [Accepted: 04/08/2023] [Indexed: 05/15/2023] Open
Abstract
Lymph node (LN) status is the most significant prognostic factor for invasive urothelial bladder cancer (UBC); however, the optimal extent of LN dissection (LND) is debated. We assessed circulating matrix metalloproteinase-7 (MMP-7) as a prognostic factor and decision-making marker for the extent of LND. Preoperative serum MMP-7 levels were determined in two independent UBC cohorts (n = 188; n = 68) and in one control cohort (n = 97) by using the ELISA method. A systematic review and meta-analysis on the prognostic role of circulating pretreatment MMP-7 levels were performed. Serum MMP-7 levels were higher in patients compared to controls (p < 0.001) with the highest levels in LN-positive cases. Half of LN-positive UBC patients had low MMP-7 levels, whereas the survival of LN-negative patients with high serum MMP-7 findings was poor. MMP-7 levels were independently associated with poor survival in both cohorts (p = 0.006, p < 0.001). Accordingly, our systematic review of six eligible publications revealed a 2.5-fold higher mortality risk in patients with high MMP-7 levels. In conclusion, preoperative MMP-7 level is a validated and independent prognostic factor in urothelial cancer. It cannot be used to decide between regional or extended LND but may be useful in identifying LN-negative high-risk patients with potentially undetected metastases.
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[Current diagnostic and treatment strategies for urachal cancer]. Orv Hetil 2023; 164:602-609. [PMID: 37087728 DOI: 10.1556/650.2023.32754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 02/18/2023] [Indexed: 04/24/2023]
Abstract
Urachal carcinoma is a rare malignancy that is uniquely associated with the field of urology. Urachal carcinoma is mostly diagnosed in urological care centers due to its most frequently presenting symptom that is hematuria. Currently available diagnostic and therapeutic knowledge is solely based on case reports and single center series, while no prospective clinical studies are carried out due to the modest number of patients. These circumstances have made creating professional guidelines challenging, hence the treatment of urachal carcinoma is commonly based on individual clinical decisions. In this review, we summarize the epidemiology, diagnostic modalities, prognosis as well as local and systemic therapeutic approaches of urachal carcinoma. Furthermore, we aim to draw conclusions from this knowledge base that may guide clinical decision-making. Finally, we highlight some of the novel therapeutic strategies that hold the potential to improve urachal carcinoma patients' prognosis and quality of life. Orv Hetil. 2023; 164(16): 602-609.
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Molecular analysis of urothelial carcinoma to predict the efficacy of immune checkpoint inhibitor therapy. Eur Urol 2023. [DOI: 10.1016/s0302-2838(23)01202-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Elevated Pre-Treatment Serum MMP-7 Levels Are Associated with the Presence of Metastasis and Poor Survival in Upper Tract Urothelial Carcinoma. Biomedicines 2022; 10:biomedicines10030698. [PMID: 35327500 PMCID: PMC8945654 DOI: 10.3390/biomedicines10030698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 03/09/2022] [Accepted: 03/15/2022] [Indexed: 12/10/2022] Open
Abstract
Upper tract urothelial carcinoma (UTUC) is a rare cancer with a barely predictable clinical behaviour. Serum MMP-7 is a validated prognostic marker in urothelial bladder cancer, a tumour entity with large clinical, histological, and molecular similarity to UTUC. The serum MMP-7 levels have not yet been investigated in UTUC. In the present study, we determined MMP-7 concentrations in an overall number of 103 serum samples from 57 UTUC patients who underwent surgical or systemic (platinum or immune checkpoint inhibitor) therapy by using the ELISA method. In addition to pre-treatment samples, the serum samples collected at predefined time points after or during therapy were also investigated. Serum MMP-7 concentrations were correlated with clinicopathological and follow-up data. Our results revealed significantly, two-fold elevated pre-treatment serum MMP-7 levels in metastatic cases of UTUC in both the radical surgery- and the chemotherapy-treated cohorts (p = 0.045 and p = 0.040, respectively). In addition, high serum MMP-7 levels significantly decreased after radical surgery, and high pre-treatment MMP-7 concentrations were associated with shorter survival both in the surgery- and chemotherapy-treated cohorts (p = 0.029 and p = 0.001, respectively). Our results revealed pre-treatment serum MMP-7 as a prognostic marker for UTUC, which may help to improve preoperative risk-stratification and thereby improve therapeutic decision-making.
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Oncological relevance of gut and urine microbiomes. Orv Hetil 2021; 162:579-586. [PMID: 33798103 DOI: 10.1556/650.2021.32052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 10/08/2020] [Indexed: 11/19/2022]
Abstract
Összefoglaló. Az immunrendszer nem megfelelő működése meghatározó szerepet játszik a daganatok kialakulásában, progressziójában és az egyes terápiák hatékonyságában is. A bélrendszer baktériumai a szervezet immunitásán keresztül képesek befolyásolni a szervezet gyógyszeres terápiákra adott válaszreakcióját, kiváltképpen az immunellenőrzőpont-gátló kezelések hatását. Az újgenerációs nukleinsav-szekvenálási technológiák felhasználásával részletes képet kaphatunk a szervezetben jelen lévő baktériumok minőségi és mennyiségi viszonyairól. A közelmúltban összefüggést igazoltak a vastagbéldaganat, a melanoma, a vesesejtes carcinoma és a nem kissejtes tüdőrák esetén alkalmazott immunellenőrzőpont-gátló terápiák hatékonysága és a bél mikrobiom-összetétele között. Számos olyan baktériumot azonosítottak, melynek jelenlétéből, illetve mennyiségéből következtethetünk az egyes kezelésekkel szembeni egyéni érzékenységre. Ezzel összhangban, az antibiotikumkezelés által okozott dysbiosis növelte az immunellenőrzőpont-gátló terápia sikertelenségének kockázatát. Ezen eredmények tükrében a jövőben a mikrobiom-összetétel meghatározása is fontos tényező lehet az immunterápiák hatékonyságának előrejelzésében, illetve egyre inkább bizonyított, hogy a széles spektrumú antibiotikumkezelés a legtöbbször csökkenti a daganatellenes immunterápiák hatékonyságát. Jelenleg folyó klinikai vizsgálatok pedig a mikrobiom-összetétel mesterséges úton történő megváltoztatásának terápiás lehetőségeit tanulmányozzák. Bebizonyosodott, hogy a korábbi állásponttal szemben a vizelet nem steril. DNS-szekvenálás alkalmazásával számos olyan, a vizeletben előforduló baktériumot sikerült azonosítani, melynek jelenléte hozzájárulhat a húgyhólyagrák kialakulásához és progressziójához, illetve a húgyhólyagban lokálisan alkalmazott BCG-terápia hatékonyságához. Jelen munkában a közelmúlt publikációit feldolgozva összefoglaljuk, mely baktériumok jelenléte hozható összefüggésbe a különböző daganatok kialakulásával, progressziójával és terápiarezisztenciájával. Orv Hetil. 2020; 162(15): 579-586. Summary. Dysfunction of the immune system plays a crucial role in the development and progression of cancer as well as the effectiveness of antitumor therapies. Gut microbiota, due to their impact on the immune system, are able to influence response to anticancer drug therapies. Next-generation DNA-sequencing technologies enabled a comprehensive quantitative and qualitative exploration of the gut microbiome. An increasing body of evidence indicates the association between the efficacy of immune checkpoint inhibitor therapies and gut microbiome composition in colorectal cancer, malignant melanoma, renal cell carcinoma, and non-small cell lung cancer. Recently, several bacterial strains and species were shown to be associated with treatment efficacies. In accordance, dysbiosis caused by antibiotic treatment was found to increase the risk of failure to immune checkpoint inhibitor therapies. In the light of these results, examination of microbiome composition may become an important factor for the prediction of immunotherapies. Currently ongoing clinical trials are investigating the potential of therapeutic alteration of microbiome composition. Contrary to the previous view, urine has been shown not to be sterile. By using sensitive DNA-sequencing technologies, several urinary bacteria could be identified which may contribute to the development and progression of bladder cancer and may influence the efficacy of intravesical BCG therapy. In the present work, we summarize recent studies that identified the presence of certain bacteria associated with the development, progression, and therapy resistance of various cancers. Orv Hetil. 2020; 162(15): 579-586.
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Large Stokes-shift bioorthogonal probes for STED, 2P-STED and multi-color STED nanoscopy. Methods Appl Fluoresc 2021; 9:015006. [PMID: 33427202 DOI: 10.1088/2050-6120/abb363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Synthesis and multiple STED imaging applications of four, red-emitting (610-670 nm), tetrazine-functionalized fluorescent probes (CBRD = Chemical Biology Research group Dye 1-4) with large Stokes-shift is presented. Present studies revealed the super-resolution microscopy applicability of the probes as demonstrated through bioorthogonal labeling scheme of cytoskeletal proteins actin and keratin-19, and mitochondrial protein TOMM20. Furthermore, super-resolved images of insulin receptors in live-cell bioorthogonal labeling schemes through a genetically encoded cyclooctynylated non-canonical amino acid are also presented. The large Stokes-shifts and the wide spectral bands of the probes enabled the use of two common depletion lasers (660 nm and 775 nm). The probes were also found suitable for super-resolution microscopy in combination with two-photon excitation (2P-STED) resulting in improved spatial resolution. One of the dyes was also used together with two commercial dyes in the three-color STED imaging of intracellular structures.
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The prognostic value of serum MMP-7 levels in prostate cancer patients who received docetaxel, abiraterone, or enzalutamide therapy. Urol Oncol 2020; 39:296.e11-296.e19. [PMID: 33046366 DOI: 10.1016/j.urolonc.2020.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/06/2020] [Accepted: 09/12/2020] [Indexed: 12/24/2022]
Abstract
OBJECTIVES The rapidly changing treatment landscape in metastatic castration-resistant prostate cancer (mCRPC) calls for biomarkers to guide treatment decisions. We recently identified MMP-7 as a potential serum marker for the prediction of response and survival in mCRPC patients who received docetaxel (DOC) chemotherapy. Here, we aimed to test this finding in an independent patient cohort and in addition to explore the prognostic potential of serum MMP-7 in abiraterone (ABI) or enzalutamide (ENZA) treated patients. METHODS AND MATERIALS MMP-7 levels were measured in 836 serum samples from 320 mCRPC patients collected before and during DOC (n = 95), ABI (n = 140), or ENZA (n = 85) treatment by using the ELISA method. Results were correlated with clinical and follow-up data. RESULTS MMP-7 baseline levels were similar between the 3 treatment groups. In the ABI and ENZA cohorts, baseline MMP-7 levels were lower in patients with prior radical prostatectomy (P = 0.058 and P = 0.041, respectively). Baseline MMP-7 levels above the median were associated with shorter overall survival for the DOC (P = 0.001) and ENZA (P = 0.006) cohorts. Multivariable analyses in the DOC and ENZA cohorts revealed that high pretreatment MMP-7 level is an independent risk factor for patients' survival. In addition, in DOC-treated patients with high baseline MMP-7 level, marker decrease at the third DOC cycle was associated with improved survival. Patients with high baseline MMP-7 levels had better survival when treated with ABI compared to DOC or ENZA. CONCLUSIONS We confirmed the prognostic value of pretreatment MMP-7 serum level and its changes as independent predictors of survival in DOC-treated mCRPC patients. In addition, high MMP-7 was a negative predictor in ENZA-treated but not in ABI-treated patients. These results warrant further research to confirm the predictive value of serum MMP-7 and to explore the potential mechanistic involvement of MMP-7 in DOC and ENZA resistance of mCRPC patients.
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Az áttétes kasztrációrezisztens prosztatarák gyógyszer-rezisztenciájának molekuláris vonatkozásai. Orv Hetil 2020; 161:813-820. [DOI: 10.1556/650.2020.31734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Absztrakt:
A metasztatikus kasztrációrezisztens prosztatarák kezelésére az elmúlt években
számos új, különböző hatásmechanizmusú gyógyszeres kezelés vált elérhetővé. Ez a
fejlődés a terápiás döntéshozatalt egyre nehezebbé teszi. Az újabb kezelésekkel
szemben is megfigyelhető az alapvonali, a szerzett és a keresztrezisztencia
jelensége is. Ezért tehát az elsődleges terápia helyes megválasztása mellett, az
azt követő vonalakban alkalmazott kezelések sorrendje és alkalmazásuk ideje is
optimalizálásra szorul. Az újabb kezelésekkel kapcsolatos
rezisztenciamechanizmusok egyre nagyobb mértékben válnak ismertté. Ezzel a
terápiatervezés az eddigi empirikus – főleg a kipróbálásra építő – irányából
egyre inkább a racionális – az adott daganat molekuláris sajátságait is
figyelembe vevő –, személyre szabott kezelés irányába mozdul el. Ebben az
összefoglaló közleményben ismertetjük azokat a rezisztenciamechanizmusokat,
amelyek a metasztatikus kasztrációrezisztens prosztatarák kezelésében
leggyakrabban használt három gyógyszerrel – docetaxel, abirateron és enzalutamid
– kapcsolatosak. Többek között áttekintést nyújtunk a MDR- (multidrogrezisztens)
fehérjéken keresztül megvalósuló, az androgénreceptor-, a Wnt-, a p53-szignálút,
valamint a DNS hibajavító mechanizmusában részt vevő gének (mint például a
BRCA és ATM) sérüléseivel összefüggésben
kialakuló és a neuroendokrin differenciáció által kiváltott
rezisztenciamechanizmusokról. Orv Hetil. 2020; 161(20): 813–820.
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Abstract
Investigations on electrostatic collection of thoron decay products as a function of field strength in a special source-electrode arrangement have been performed. Yields of the decay products vs. field strength were measured by solid state silicon and CR-39 track-etched detectors. Results show a significant space charge effect on the yield of collected products if an insulator is placed between the electrodes. The intensities of the collected thoron daughters are influenced strongly by the air stream present in the cell.
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Development of immunosensor based on OWLS technique for determining Aflatoxin B1 and Ochratoxin A. Biosens Bioelectron 2006; 22:797-802. [PMID: 16600588 DOI: 10.1016/j.bios.2006.02.015] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 02/15/2006] [Accepted: 02/20/2006] [Indexed: 10/24/2022]
Abstract
Mycotoxins are toxic secondary metabolites produced by a number of different fungi, and can be present in a wide range of food and feed commodities including cereal grains, oil seeds, dried fruits, apple juice, wine and meat products from animals fed contaminated meal. Many mycotoxins are highly resistant, and survive food processing, and therefore enter the food chain and provide a threat to human health. The optical waveguide lightmode spectroscopy (OWLS) technique has been applied to the detection of Aflatoxin and Ochratoxin in both competitive and in direct immunoassays. After immobilizing the antibody or antigen conjugate for the direct or indirect measurement, respectively, the sensor chip was used in flow-injection analyser (FIA) system. When using non-competitive method, sensor responses were obtained first only at analyte concentrations of 5-10 ng ml(-1). In both cases, the responses were very unstable. For competitive sensor investigation with the sensitized chip first the optimal dilution rate of monoclonal antibodies was determined, for the measurement of Ochratoxin A and Aflatoxin B1 the monoclonal antibody stock solution was diluted to 1 microg ml(-1) and to a 1:400 dilution, respectively. During the competitive measurement standard solutions were mixed with monoclonal antibodies at the appropriate concentration, the mixture was incubated for 1 min and injected into the OWLS system. The sensitive detection range of the competitive detection method was between 0.5 and 10 ng ml(-1) in both cases. After the establishment of the indirect method, barley and wheat flour samples were measured, and the results were in good correlation by those measured by enzyme linked immuno-sorbent assay (ELISA). Regression coefficient between the two methods for Ochratoxin and Aflatoxin was determined as 0.96 and 0.89, respectively.
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Editorial - Biosensor as a new tool in food analysis. ACTA ALIMENTARIA 2005. [DOI: 10.1556/aalim.34.2005.3.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Investigation of organic phase biosensor for measuring glucose in flow injection analysis system. Anal Chim Acta 2004. [DOI: 10.1016/j.aca.2003.09.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Determination of selenium balance in healthy children by aas-hydride generation and by inaa technique. ACTA ALIMENTARIA 2002. [DOI: 10.1556/aalim.31.2002.3.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Modification of the surface of integrated optical wave-guide sensors for immunosensor applications. FRESENIUS' JOURNAL OF ANALYTICAL CHEMISTRY 2001; 371:21-4. [PMID: 11605752 DOI: 10.1007/s002160100929] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Methods have been developed which enable attachment amino and epoxy groups to the surface of integrated optical wave-guide sensors for immunosensor applications. The SiO2-TiO2 surfaces were modified by use of the trifunctional silane reagents gamma-aminopropyltriethoxysilane (APTS) and gamma-glycidoxypropyltrimethoxysilane (GOPS) in organic and/or in inorganic phases. Silanization methods were optimized taking into consideration the concentration of silane reagent used and the temperature and time of reaction. To evaluate the layers formed, immobilization experiments were undertaken on the modified surfaces using the bovine serum albumin (BSA)-anti-BSA IgG antibody model molecule pair. The regenerability of the sensitized surfaces was also studied.
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Multi-enzyme biosensors with amperometric detection for determination of lactose in milk and dairy products. Eur Food Res Technol 1999. [DOI: 10.1007/s002170050484] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Determination of the ratio of D- and L-amino acids in brewing by an immobilised amino acid oxidase enzyme reactor coupled to amperometric detection. Biosens Bioelectron 1999; 14:335-40. [PMID: 10230034 DOI: 10.1016/s0956-5663(98)00130-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To determine the quantity of free amino acids, the D- and L-forms separately, is an important task in modern nutritional studies. The aim of our present work was to develop rapid, routine methods for fast determination of the different forms of free amino acids. We utilized two enzymes (L-amino acid oxidase, D-amino acid oxidase) with broad specificity. In our home-made reactors, the enzymes were immobilized in a thin-layer Plexi-cell on natural protein membrane. The enzyme-cell was built into a FIA system and the hydrogen peroxide generated during the enzymatic reaction was determined by an amperometric detector. The electrode potential was fixed at +100 mV. The parameters for the biochemical and electrochemical reactions were optimized in each case. The optimal pH value for measuring L- and D-amino acids was found ca. 8.8 and 9.5, respectively. The LAO reactor could be used for more than 900 measurements, while the DAO reactor for about 1000 measurements. The working concentration range was between 0.1-3 and 0.2-3 mM, respectively. The same standard solution (L- and D-Methionine, 1 mM) was injected 25 times sequentially and the standard deviations were 2 and 2.7%, respectively. After determining the optimal parameters, the specificity of the immobilized enzyme preparations towards different amino acids and in samples from different stages of brewing was investigated.
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An improved neutron reflection setup for the determination of H and (O+C)/H in oil samples. J Radioanal Nucl Chem 1997. [DOI: 10.1007/bf02039333] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The quality and quantity of different sugars play a very important role in studying the carbohydrate metabolism of yeast. During the bioprocesses there is a need to follow the concentrations of these sugars. Authors have reported on the development of biosensors for determination of glucose and maltose previously. The aim of this research was to construct a sensor for determining galactose in fermentation broths to prepare the basis for an online monitoring system. Using a modified thin-layer enzyme cell connected to an electrochemical detector cell, a biosensor has been developed for this purpose. Galactose was oxidized with immobilized galactose oxidase enzyme (EC 1.1.3.9) and the hydrogen peroxide generated during the enzyme reaction was determined with an amperometric detector. The parameters for the biochemical and electrochemical reactions were optimized. The pH optimum of 6.6 was found when using phosphate buffer. The buffer solution completed by micro elements (Mg2+, Se2+) gave more stable signs. The activities for raffinose, lactose, glycerol and dihydroxyacetone were 68, 16, 6 and 430%, respectively. With the thin-layer cell more than 900 samples were measured in 6 weeks. Samples obtained from different fermentations were measured with the newly developed galactose sensor and the results were compared with the standard UV method. The correlation coefficient was 0.991. The results showed that the application of the new biosensor was successful.
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Abstract
If a fermentation process is followed by a change in the concentration of maltose, information on the level of the maltose is important. A new type of sensor was developed for measuring the content of maltose in fermentation broth. The base of the sensor is a thin-layer reactor, in which a protein membrane was chosen for the immobilization of enzymes. To measure maltose, we investigated the influence of enzymes such as alpha-glucosidase (EC 3.2.1.20) and amyloglucosidase (EC 3.2.1.3) on the effectiveness of conversion to glucose. Because amyloglucosidase proved to be more effective, a mixture of amyloglucosidase and glucose oxidase was applied for the determination of maltose. To develop the best measuring technique, the consequences of changes in different parameters, such as the optimal ratio of enzymes, role of pH value and that of the flow rate, were studied. An amperometric measuring cell with Pt-Ag/AgCl-Pt electrodes was used at +600 mV operating potential. The results indicate that the maltose content in different types of fermentation broth can be determined by the new measuring cell in the range of 0.2-4 mM maltose. The cell was successfully tested in the fermentation of brewer's yeast.
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Determination of Ta impurities in Nb samples by X-rays in neutron activation analysis. J Radioanal Nucl Chem 1991. [DOI: 10.1007/bf02163881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Determination of Cu in minerals by 14-MeV neutron activation analysis and radiochemical separation. J Radioanal Nucl Chem 1986. [DOI: 10.1007/bf02164941] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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