Prospective Evaluation of Aspergillus fumigatus-Specific IgG in Patients With Cystic Fibrosis

Background: In Cystic Fibrosis (CF), the airways are often colonized by opportunistic fungi. The most frequently detected mold is Aspergillus fumigatus (Af). Af diseases are associated with significant morbidity and mortality. The most common clinical picture caused by Af is allergic bronchopulmonary aspergillosis (ABPA), triggered by an immunological reaction against Af. Af bronchitis and invasive aspergillosis rarely occur in CF as a result of spore colonization and germination. Since pulmonary mycoses and exacerbations by other pathogens overlap in clinical, radiological, and immunological characteristics, diagnosis still remains a challenge. The search for reliable, widely available biomarkers for Af diseases is therefore still an important task today. Objectives: Af-specific IgG m3 is broadly available. Sensitivity and specificity data are contradictory and differ depending on the study population. In our prospective study on pulmonary Af diseases in CF, we determined specific IgG m3 in order to test its suitability as a biomarker for acute Af diseases and as a follow-up parameter. Methods: In this prospective single center study, 109 patients with CF were screened from 2016 to 2019 for Af-associated diseases. According to diagnostic criteria, they were divided into four groups (control, bronchitis, ABPA, pneumonia). The groups were compared with respect to the level of Af-specific IgG (ImmunoCAP Gm3). We performed a receiver operating characteristic (ROC) curve analysis to determine cut-off, sensitivity and specificity. Twenty-one patients could be enrolled for a follow-up examination. Results: Of the 109 patients, 36 were classified as acute Af-disease (Af bronchitis, ABPA, Af pneumonia). Of these, 21 patients completed follow up-screening. The median Af-specific Gm3 was higher in the acute Af-disease groups. There was a significant difference in Af-specific IgG m3 compared to the control group without acute Af-disease. Overall, there was a large interindividual distribution of Gm3. A cut-off value of 78.05 mg/L for Gm3 was calculated to discriminate controls and patients with ABPA/pneumonia with a specificity of 75% and a sensitivity of 74.6%. The follow up examination of 21 patients showed a decrease of Gm3 in most patients without statistical significance due to the small number of follow up patients. Conclusion: Af specific IgG may be a useful biomarker for acute ABPA and Af pneumonia, but not for Af bronchitis in CF. However, due to the large interindividual variability of Gm3, it should only be interpreted alongside other biomarkers. Therefore, due to its broad availability, it could be suitable as a biomarker for ABPA and Af pneumonia in CF, if the results can be supported by a larger multicenter cohort

Verlauf der zellulären Immunantwort bei Lebendnierenempfängern - Messung von IFN-γ und IL-17 im Elispot-Assay

Die Nierentransplantation ermöglicht Patienten die Wiederherstellung der Nierenfunktion. Aufgrund der begrenzten Verfügbarkeit an Organen nimmt dabei die Zahl der Transplantationen von einem lebenden Spender stetig zu. Zudem ermöglichen die präzisen und genauen Vorbereitungen und Abläufe bei Lebendnierenspenden eine bessere 5-Jahres-Überlebensrate als bei Kadaverspenden. Die genetische Verschiedenheit zwischen Spender und Empfänger bedingt jedoch eine lebenslange immunsuppressive Therapie, um Abstoßungsreaktionen und damit das Scheitern einer Organtransplantation zu verhindern. An den Universitätskliniken Leipzig und Halle/Saale besteht diese Therapie aus einer Dreifachkombination von Tacrolimus, Mycophenolat-Mofetil und Prednisolon, wobei mögliche Nebenwirkungen wie opportunistische Infektionen, kardiovaskuläre und metabolische Erkrankungen sowie Tumore in Kauf genommen werden. Zudem besteht für den immunsupprimmierten Organismus die ständige Gefahr einer Abstoßungsreaktion. Diese Aspekte führen bei den Empfängern zu einer massiven Einschränkung der Gesundheit und Lebensqualität. Inwieweit die ausgeprägte Immunsuppression notwendig ist, bleibt unklar und muss individuell festgelegt werden. Bisher existiert kein geeignetes Verfahren für ein Immunmonitoring, weshalb in vielen Fällen eine umfangreiche und überdosierte Immunsuppression in Kauf genommen wird. Im Rahmen dieser Arbeit wurde ein geeignetes Testverfahren, der Elispot-Assay, für die Expression der beiden proinflammatorischen Zytokine IFN-γ und IL-17 erstellt. Dafür wurden die PBMC der Spender und Empfänger aus Vollblut separiert, um sie anschließend sowohl separat als auch in einer Lymphozytenmischreaktion zu untersuchen. Die Darstellung von IL-17 konnte nur aufgrund einer zusätzlichen Stimulation mit OKT3 gelingen, während der IFN-γ-Elispot sowohl im Leerwert als auch unter Stimulation mit IL-2 zu ausreichenden Spotanzahlen führte. Die Spotanzahlen der Spender-PBMC wurden mit Hilfe von γ-Strahlung signifikant reduziert (IFN-γ: p=0,047 | IFN-γ + IL-2: p=0,007 | IL-17: p = 0,001), um in den Lymphozytenmischreaktionen die alleinige Zytokinausschüttung der Empfänger-PBMC messen zu können. Die Spender- PBMC fungierten dabei nur als Antigene. Insgesamt konnten zwischen 2009 und 2012 zwölf von siebzehn Patientenpaaren in die Studie eingeschlossen werden. Die Spotanzahlen der Paare wurden dabei sowohl im IFN-γ- als auch im IL-17-Elispot-Assay zu vier unterschiedlichen Zeitpunkten gemessen (vor Transplantation | 21±3 d postoperativ | 28±3 d postoperativ | 75±15 d postoperativ). In den meisten Fällen zeigte sich vor Transplantation eine erhöhte Spotanzahl im Vergleich zu den drei postoperativen Werten. Zudem stiegen die Spotanzahlen sowohl für IFN-γ als auch für IL-17 nach niedrigen Messergebnissen kurz nach der Transplantation im postoperativen Verlauf wieder an und erreichten in einigen Fällen die Spotanzahl der präoperativen Ausgangswerte. Ein signifikanter Unterschied konnte aufgrund der geringen Fallzahl nicht erreicht werden. Die kurzfristige Reduktion der Spotanzahlen postoperativ ist dabei aller Wahrscheinlichkeit nach auf die hohen Dosen an immunsuppressiven Medikamenten zurückzuführen. Insgesamt zeigten die Verläufe der IFN-γ- und der IL-17- Elispot-Assays ähnliche Verläufe. Daraus lässt sich schlussfolgern, dass der IL-17-Elispot- Assay in Bezug auf mögliche Abstoßungsreaktionen eine ähnliche Aussagekraft besitzen könnte wie der bereits vielfach untersuchte IFN-γ-Elispot-Assay. Weiterhin wurden die Messergebnisse mit der Serumkreatininmolarität verglichen. Diese zeigte präoperativ höhere Molaritäten als postoperativ, wobei die postoperativen Molaritäten im Verlauf, im Gegensatz zu den Elispot-Messungen, abnahmen, was das Einsetzen der Nierenfunktion widerspiegelt. Unter den zwölf Patientenpaaren gab es keine einzige nachgewiesene akute Abstoßungsreaktion, der Verlauf der Serumkreatininmolaritäten war bei allen zwölf Empfängern vergleichbar. Demzufolge konnten die Werte der Elispot-Assays nicht herangezogen werden, um an ihnen eine Abstoßungsreaktion der transplantierten Nieren erkennen zu können. Das präoperative Abschätzen einer möglichen Abstoßungsreaktion anhand der Elispot-Assays konnte aufgrund fehlender Abstoßungsreaktionen ebenfalls nicht untersucht werden. Zusätzlich wurde bei den Patienten eine HLA-Typisierung vorgenommen, wobei der Bereich von optimalen bis maximal ungünstigen Konstellationen reichten (HLA-Mismatch: 0-0-0 bis 2-2-2). Auch hier konnten die Ergebnisse nicht mit möglichen Abstoßungsreaktionen verglichen werden. In der vorliegenden Arbeit wurden zahlreiche Varianten untersucht, die das Abschätzen einer Immunreaktion nach Nierentransplantation (Immunmonitoring) ermöglichen könnten. Aufgrund fehlender Abstoßungsreaktionen bei den Empfängern konnte das Testverfahren nicht an den klinischen Verläufen validiert werden. Mit dem in dieser Arbeit entwickelten Messverfahren kann jedoch eine neue und größer angelegte Studie erfolgen, die in Zukunft ein Immunmonitoring bei Patienten nach Nierentransplantation ermöglicht.:I Inhaltsverzeichnis................................................................I II Bibliographische Beschreibung....................................................................IV III Abkürzungsverzeichnis...................................................................................V 1 Einleitung...........................................................................................................01 1.1 Die T-Zell-vermittelte Immunität..................................................................01 1.1.1 Die verschiedenen Klassen der T-Lymphozyten................................ 01 1.1.2 Interferon-gamma als proinflammatorisches Zytokin......................... 04 1.1.3 Interleukin-17............................................................................................. 04 1.2 Die Nierentransplantation........................................................................... 05 1.2.1 Einführung.................................................................................................. 05 1.2.2 Besonderheiten der Lebendnierenspenden........................................ 06 1.3 Therapeutika bei Lebendnierenspenden................................................. 07 1.3.1 Calcineurininhibitoren............................................................................... 07 1.3.2 Prednisolon.................................................................................................. 08 1.3.3 Mycophenolat-Mofetil................................................................................. 09 1.4 Komplikationen bei Transplantationen....................................................... 10 1.4.1 Opportunistische Infektionen..................................................................... 10 1.4.2 Kardiovaskuläre und metabolische Erkrankungen................................ 11 1.4.3 Maligne Tumore.............................................................................................11 1.5 Transplantatrejektion........................................................................................ 12 1.5.1 Akute Abstoßungsreaktion............................................................................12 1.5.2 Chronische Transplantatnephropathie......................................................13 1.6 Zielsetzung der Arbeit.......................................................................................15 I2 Materialien und Methoden................................................................................. 16 2.1 Studiendesign.................................................................................................... 16 2.2 Materialien.......................................................................................................... 17 2.3 Methoden............................................................................................................ 19 2.3.1 Blutentnahmen................................................................................................ 19 2.3.2 Lymphozytenseparation.................................................................................19 2.3.3 Bestimmung der Zellzahl............................................................................... 20 2.3.4 Kryokonservierung der Zellen...................................................................... 20 2.3.5 Auftauen von kryokonservierten Zellen...................................................... 20 2.3.6 Bestrahlung von Zellen...................................................................................21 2.3.7 Stimulanzien.................................................................................................... 21 2.3.8 Durchflusszytometrie...................................................................................... 22 2.3.9 Elispot-Assay.................................................................................................... 23 3 Ergebnisse............................................................................................................... 29 3.1 Charakteristika der Patienten............................................................................ 29 3.2 Medikamentöse Therapieschemata nach Nierentransplantationen.......... 32 3.3 Versuche zur Etablierung des Elispot-Verfahrens......................................... 33 3.3.1 Vorversuche zum Nachweis von IFN-γ........................................................ 34 3.3.2 Vorversuche zum Nachweis von IL-17........................................................ 36 3.3.3 Versuche mit FKS-freiem Medium.................................................................37 3.3.4 Vitalitätsmessung in der Durchflusszytometrie.......................................... 38 3.4 Vergleich von Buffy Coats mit Patientenproben im Elispot-Assay..............38 3.5 Elispot-Assays der Spender-Empfänger-Paare............................................ 39 3.5.1 Ergebnisse der Elispot-Assays zum Nachweis von IFN-γ........................40 3.5.2 Ergebnisse der Elispot-Assays zum Nachweis von IL-17....................... 45 II3.6 Elispot-Ergebnisse unter Berücksichtigung der HLA-Kompatibilität........49 4 Diskussion............................................................................................................... 50 4.1 Bewertung der Methoden.................................................................................. 51 4.1.1 Patientenauswahl und -akquirierung........................................................... 51 4.1.2 Durchflusszytometrie....................................................................................... 51 4.1.3 Elispot-Assay..................................................................................................... 52 4.2 Vitalitätsmessung................................................................................................. 53 4.3 Elispot-Ergebnisse............................................................................................... 53 4.3.1 Vergleich der unbestrahlten und bestrahlten Elispot-Assays................... 53 4.3.2 Elispot-Assays der Patienten.......................................................................... 54 4.3.2.1 IFN-γ-Elispot-Assay........................................................................................ 54 4.3.2.2 IL-17-Elispot-Assay.........................................................................................56 4.3.2.3 IFN-γ-Elispot-Assay und IL-17-Elispot-Assay im Vergleich.................... 57 4.4 HLA-Merkmale und Serumkreatininmolarität...................................................58 4.5 Schlussfolgerung und Ausblick...........................................................................59 5 Zusammenfassung...................................................................................................62 6 Abstract...................................................................................................................... 65 7 Literaturverzeichnis................................................................................................. 67 8 Tabellenverzeichnis.................................................................................................83 9 Abbildungsverzeichnis........................................................................................... 84 10 Erklärung über die eigenständige Verfassung der Arbeit............................. 85 11 Lebenslauf..............................................................................................................86 12 Danksagung.......................................................................................................... 87Introduction Since the first kidney transplantation in the 1950ies, kidney transplantation is still being challenged by graft dysfunction and complete graft failure. Permanent immunsuppressive treatment is mandatory to avoid an unfavourable outcome. The treatment with Prednisolone, Tacrolimus and Mycophenolat-Mofetil may cause toxic side effects resulting in Diabetes mellitus, hypertension, infections and cancer. In the present study we tried to demonstrate that the amount of spots in the Enzyme linked immunospot assay (Elispot-Assay) of IFN-γ and IL-17 correlates with the probability of graft dysfuction and complete graft failure. We also compared the results to clinical parameters. Methods Between the years 2009 and 2012, twelve pairs of related living kidney transplantations were included in this study. From each pair blood samples were taken at four time points (before transplantation, and at 21±3, 28±3 and 75±15 days after kidney transplantation, respectively). After establishing the technique of IFN-γ- and IL-17-Elispot-Assays, we separated the periphale blood mononuclear cells (PBMC) and performed follow up examinations at the four time points mentioned above. The PBMC of each donor and each recipient were examined separatly, and in addition together in a lymphocyte mixed reaction. We stimulated the PBMC of the IFN-γ-Elispot with Interleukin-2 (IL-2) and the PBMC of the IL-17-Elispot with OKT3 to get significant characteristics. PBMC of the donors were irradiated with 30 Gy before mixing them with the PBMC of the recipients. We also took the HLA-matches and serum creatinine molarity to compare important clinical parameters with the results of the Elispot-Assays. Results Sufficient spots were measured using the unstimulated and stimulated IFN-γ-Elispot and the stimulated IL-17-Elispot. Radiation was significant at all three tests (IFN-γ: p=0,047 | IFN-γ + IL-2: p=0,007 | IL-17: p = 0,001). All twelve recipients showed a high number of spots before transplantation in both types of Elispot-Assays and most of them an increasing number of spots after a minimal turning point three weeks after transplantation. Due to the small number of cases, no significant results could be obtained at follow up. Non recipient developed a graft rejection as proven by biopsy or graft failure. The molarity of serum creatinine was permanently reduced whereas it was high before transplantation. Because of the abscence of any rejection episodes, HLA matches could not be compared. Discussion Due to the absence of rejection episodes or graft failure, no prediction for rejection by the IFN-γ- and IL-17-Elispot was possible. The low number of cases of living related kidney transplantation demonstrated the challange of the investigation of living related kidney transplantation. Although we could prove a significant effect of the irradiation of PBMC, there was no significant result in the follow up investigations. A higher number of cases are needed in future investigations. The established method of the IFN-γ- and IL-17-Elispot can be used in a future study with an extended number of cases and a longer follow up of time.:I Inhaltsverzeichnis................................................................I II Bibliographische Beschreibung....................................................................IV III Abkürzungsverzeichnis...................................................................................V 1 Einleitung...........................................................................................................01 1.1 Die T-Zell-vermittelte Immunität..................................................................01 1.1.1 Die verschiedenen Klassen der T-Lymphozyten................................ 01 1.1.2 Interferon-gamma als proinflammatorisches Zytokin......................... 04 1.1.3 Interleukin-17............................................................................................. 04 1.2 Die Nierentransplantation........................................................................... 05 1.2.1 Einführung.................................................................................................. 05 1.2.2 Besonderheiten der Lebendnierenspenden........................................ 06 1.3 Therapeutika bei Lebendnierenspenden................................................. 07 1.3.1 Calcineurininhibitoren............................................................................... 07 1.3.2 Prednisolon.................................................................................................. 08 1.3.3 Mycophenolat-Mofetil................................................................................. 09 1.4 Komplikationen bei Transplantationen....................................................... 10 1.4.1 Opportunistische Infektionen..................................................................... 10 1.4.2 Kardiovaskuläre und metabolische Erkrankungen................................ 11 1.4.3 Maligne Tumore.............................................................................................11 1.5 Transplantatrejektion........................................................................................ 12 1.5.1 Akute Abstoßungsreaktion............................................................................12 1.5.2 Chronische Transplantatnephropathie......................................................13 1.6 Zielsetzung der Arbeit.......................................................................................15 I2 Materialien und Methoden................................................................................. 16 2.1 Studiendesign.................................................................................................... 16 2.2 Materialien.......................................................................................................... 17 2.3 Methoden............................................................................................................ 19 2.3.1 Blutentnahmen................................................................................................ 19 2.3.2 Lymphozytenseparation.................................................................................19 2.3.3 Bestimmung der Zellzahl............................................................................... 20 2.3.4 Kryokonservierung der Zellen...................................................................... 20 2.3.5 Auftauen von kryokonservierten Zellen...................................................... 20 2.3.6 Bestrahlung von Zellen...................................................................................21 2.3.7 Stimulanzien.................................................................................................... 21 2.3.8 Durchflusszytometrie...................................................................................... 22 2.3.9 Elispot-Assay.................................................................................................... 23 3 Ergebnisse............................................................................................................... 29 3.1 Charakteristika der Patienten............................................................................ 29 3.2 Medikamentöse Therapieschemata nach Nierentransplantationen.......... 32 3.3 Versuche zur Etablierung des Elispot-Verfahrens......................................... 33 3.3.1 Vorversuche zum Nachweis von IFN-γ........................................................ 34 3.3.2 Vorversuche zum Nachweis von IL-17........................................................ 36 3.3.3 Versuche mit FKS-freiem Medium.................................................................37 3.3.4 Vitalitätsmessung in der Durchflusszytometrie.......................................... 38 3.4 Vergleich von Buffy Coats mit Patientenproben im Elispot-Assay..............38 3.5 Elispot-Assays der Spender-Empfänger-Paare............................................ 39 3.5.1 Ergebnisse der Elispot-Assays zum Nachweis von IFN-γ........................40 3.5.2 Ergebnisse der Elispot-Assays zum Nachweis von IL-17....................... 45 II3.6 Elispot-Ergebnisse unter Berücksichtigung der HLA-Kompatibilität........49 4 Diskussion............................................................................................................... 50 4.1 Bewertung der Methoden.................................................................................. 51 4.1.1 Patientenauswahl und -akquirierung........................................................... 51 4.1.2 Durchflusszytometrie....................................................................................... 51 4.1.3 Elispot-Assay..................................................................................................... 52 4.2 Vitalitätsmessung................................................................................................. 53 4.3 Elispot-Ergebnisse..........................................

Cyclic voltammetry studies on substituted arenesulfonhydrazides

Additional Z and Boc groups on the vicinal nitrogen of sulfonyl hydrazines have no significant effect on the cathodic potential of the sulfonyl functions as measured by cyclic voltammetry, whereas a Boc group on the geminal nitrogen invariably gives rise to shifts of about 0.2 V to less negative potential similar to those previously observed for derivatives of amines.This work was supported by the Swedish Natural Science Research Council (NFR) and the Fundaçao para a Ciência e a Tecnologia (Portugal)

Frequent Pet Contact as Risk Factor for Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis

Aspergillus fumigatus (Af) frequently colonizes the respiratory tract of patients with cystic fibrosis (CF). Af is associated with loss of pulmonary function and allergic bronchopulmonary aspergillosis (ABPA), a hypersensitivity fungal lung disease. Environmental factors have impact on CF patients' lung function variation. The aim of this nationwide questionnaire survey was to investigate the amount of CF patients with frequent pet contact including pet species and to examine the potential impact of frequent pet contact on the occurrence of Af colonization and ABPA diagnosis in these patients. The survey was carried out in 31 German CF centers in 2018. A total of 1232 who completed the surveys were included, and statistical analysis was performed by chi-squared test. Within the study cohort 49.8% of subjects (n = 614; CF patients < 18years: 49.4%, n = 234; ≥ 18years: 50.1%, n = 380) reported frequent contact to pets, of which 60.7% reported frequent contact to dogs, 42.3% to cats and other animals. Of those with frequent pet contact, 71.8% (n = 441) had contact to one pet or more pets from the same family. Af colonization was not significantly associated with frequent pet contact. ABPA diagnosis was documented in 16.7% (n = 206) of all included CF patients and was significantly associated with frequent pet contact (18.9%, n = 116, p = 0.042), confirming previous single center examinations. Particularly, patients with frequent contact to dogs showed an increased ABPA prevalence of 21.3%. Frequent pet contact might be a risk factor for ABPA. CF patients who are sensitized to Af should be informed about the increased risk to develop an ABPA by frequent pet contact. Patients with recurrent onset of ABPA should be evaluated in terms of frequent pet contact

2-naphthalenesulfonyl as a tosyl substitute for protection of amino functions. Cyclic voltammetry studies on model sulfonamides and their preparative cleavage by reduction

With the aim to develop a practically useful, reductively more labile alternative to tosyl for protection of amino functions, initially a number of N-arenesulfonyl-protected heterocycles (pyrroles, imidazoles, indole, and carbazole) have been prepared and studied by cyclic voltammetry (CV). The recorded activation potentials vary from -1.32 to -1.99 V (vs SCE). In N-sulfonylazolides such as tosylindole the cathodic potentials are shifted by over 0.5 V compared to simple sulfonamides. An additional effect of the sulfonic acid component is also indicated. Among the compounds studied, 1- and 2-naphthalenesulfollylindole give CV peaks at about 0.4 and 0.2 V, respectively, less negative potential than tosylindole. To further investigate naphthalenesulfonyl for this purpose, we have also prepared a variety of simple 1- and 2-naphthalenesulfonyl derivatives and studied them similarly. They have activation potentials above -2.14 V and are all smoothly cleaved by Mg/MeOH. The latter reagent is capable of cleaving N-arenesulfonyl derivatives that give CV peaks above -2.30 V, whereas Al(Hg) requires potentials above about -1.7 V. Selective cleavage of 2-naphthalenesulfonyl in the presence of tosyl by Mg/MeOH is demonstrated. Several examples of reductive cleavage of arenesulfonyl derivatives with Mg/MeOH, Al(Hg), and electrolysis on a preparative scale are given.This work was supported by the Swedish Natural Science Research Council (NFR), the Swedish Research Council for Engineering Sciences (TFR), Carl Tryggers Stiftelse, Astra Draco AB, and the Fundacão para a Ciência e a Tecnologia (Portugal). B.N. gratefully acknowledges the RSC for a journals grant for international authors and the ISP for a fellowship, as well as the University of Yaoundé I for a leave of absence

Urban Life as Risk Factor for Aspergillosis

Aspergillus fumigatus (Af) frequently colonizes the airways of patients with cystic fibrosis (CF) and can cause severe diseases, such as allergic bronchopulmonary aspergillosis, Af bronchitis or even Af pneumonia. However, risk factors, including environmental factors, for acquiring Af in the respiratory tract of patients with CF are rarely studied and described. The aim of this study was to investigate whether urban or rural life could affect colonization with Af in the respiratory tract of patients with CF. Due to privacy policy, registry data are usually not linked to patients ' home addresses. It is therefore very difficult to analyze the influence of the patient ' s residential environment. This prospective questionnaire survey was carried out in 31 German CF centers in 2018. Only completed surveys, including a clearly assigned type of residential area were included. Statistical analysis was performed by chi-squared test and logistic regression models. A total of 1016 questionnaires were analyzed (Patients` age: 23 ± 13; 0-88 years; female gender: n=492; 48%). The majority of patients with CF live in large cities (n =314; 30.9%) or urban districts (n=461; 45.4%). Prevalence of 30.2% was found for Af, within the 12 months of investigation period. Af colonization was significantly associated with urban life (p=0.004). Urban live should be considered as possible new risk factor for colonization with Af in the respiratory tract of patients with CF. These new results may raise the awareness of the influence of environmental factors on patient outcomes and should be included in patient guidance and preventive measures

Selective cathodic cleavage of unsymmetrical imidodicarbonates, acylcarbamates and diacylamides

A study of the selective cathodic cleavage of one of the alkoxycarbonyl or acyl groups from various imidodicarbonates, acylamides, and diacylamides is reported. The compounds investigated include all 15 possible combinations of the following groups in unsymmetrical N,N-diprotected derivatives of benzylamine: p-nitrobenzyloxycarbonyl, trichloroethyloxycarbonyl, toluene-p-sulfonyl, benzoyl, benzyloxycarbonyl, and tert-butyloxycarbonyl which can all be electrochemically cleavaged, except the last one. Initially the compounds were examined by cyclic voltammetry in order to measure the potentials associated with the cleavage of each group and afterwards they were electrolysed at constant potential in the presence of a proton donor. The following ranges in negative potential were recorded: 1.03-1.13 V [Z(NO2)], 1.8-2.14 V (Troc), 1.75-2.41 V (Tos), 1.88-2.52 V (Bz), and 2.83-2.9 V (Z), thus occasionally revealing a drastic effect of the auxiliary group. In the electrolytic experiments competitive attack by base occasionally led to mixtures of monoacylamides. However, all compounds apart from some of the trichloroethyloxycarbonyl derivatives could be selectively cleaved in 89-100% yields when an appropriate proton donor was used. Tentative explanations are given for the behaviour of the compounds studied and some conclusions are drawn

Synthesis and cathodic cleavage of a set of substituted benzenesulfonamides including the corresponding tert-butyl sulfonylcarbamates: pKa of sulfonamides

From a series of Substituted benzenesulfonic acids, most of which have previously been employed for the protection of amino functions and including a few such known to facilitate cleavage by acid, benzylamides 1a-k have been derived and studied. Initially their electrochemical cleavage potentials were determined by cyclic voltammetry in order to further explore selective deprotection within this substance group. In parallel, the corresponding tert-butyl sulfonylcarbamates 2a-k have also been prepared and studied. Among the sulfonamides investigated S-N bond cleavage was found to take place over a wide range of potentials from -1.67 to -2.64 V (excluding the nitro derivative), the most acid-labile groups requiring more negative potentials, whereas this cleavage was facilitated by 0.19-0.30 V for the sulfonylcarbamates. Small scale electrolyses of 2 at controlled potential with determination of the cleavage products formed were subsequently performed. For the N-benzylbenzenesulfonamides 1, the pK(a)s in DMSO and in some cases also in water have been determined and found to be in the range 14.0-16.4 and 10.07-11.53, respectively

Genetic diversification of persistent Mycobacterium abscessus within cystic fibrosis patients

Mycobacterium (M.) abscessus infections in Cystic Fibrosis (CF) patients cause a deterioration of lung function. Treatment of these multidrug-resistant pathogens is associated with severe side-effects, while frequently unsuccessful. Insight on M. abscessus genomic evolvement during chronic lung infection would be beneficial for improving treatment strategies. A longitudinal study enrolling 42 CF patients was performed at a CF center in Berlin, Germany, to elaborate phylogeny and genomic diversification of in-patient M. abscessus. Eleven of the 42 CF patients were infected with M. abscessus. Five of these 11 patients were infected with global human-transmissible M. abscessus cluster strains. Phylogenetic analysis of 88 genomes from isolates of the 11 patients excluded occurrence of M. abscessus transmission among members of the study group. Genome sequencing and variant analysis of 30 isolates from 11 serial respiratory samples collected over 4.5 years from a chronically infected patient demonstrated accumulation of gene mutations. In total, 53 genes exhibiting non-synonymous variations were identified. Enrichment analysis emphasized genes involved in synthesis of glycopeptidolipids, genes from the embABC (arabinosyltransferase) operon, betA (glucose-methanol-choline oxidoreductase) and choD (cholesterol oxidase). Genetic diversity evolved in a variety of virulence- and resistance-associated genes. The strategy of M. abscessus populations in chronic lung infection is not clonal expansion of dominant variants, but to sustain simultaneously a wide range of genetic variants facilitating adaptation of the population to changing living conditions in the lung. Genomic diversification during chronic infection requires increased attention when new control strategies against M. abscessus infections are explored.Peer Reviewe