103 research outputs found
DNA bending by photolyase in specific and non-specific complexes studied by atomic force microscopy
No full textSpecific and non-specific complexes of DNA and photolyase are visualised by atomic force microscopy. As a substrate for photolyase a 1150 bp DNA restriction fragment was UV-irradiated to produce damaged sites at random positions. Comparison with a 735 bp undamaged DNA fragment made it possible to separate populations of specific and non-specific photolyase complexes on the 1150 bp fragment, relieving the need for highly defined substrates. Thus it was possible to compare DNA bending for specific and non-specific interactions. Non-specific complexes show no significant bending but increased rigidity compared to naked DNA, whereas specific complexes show DNA bending of on average 36°and higher flexibility. A model obtained by docking shows that photolyase can accommodate a 36°bent DNA in the vicinity of the active site
Diagnosing acute kidney injury ahead of time in critically ill septic patients using kinetic estimated glomerular filtration rate
No full textIntroduction: Accurate and actionable diagnosis of Acute Kidney Injury (AKI) ahead of time is important to prevent or mitigate renal insufficiency. The purpose of this study was to evaluate the performance of Kinetic estimated Glomerular Filtration Rate (KeGFR) in timely predicting AKI in critically ill septic patients. Methods: We conducted a retrospective analysis on septic ICU patients who developed AKI in AmsterdamUMCdb, the first freely available European ICU database. The reference standard for AKI was the Kidney Disease: Improving Global Outcomes (KDIGO) classification based on serum creatinine and urine output (UO). Prediction of AKI was based on stages defined by KeGFR and UO. Classifications were compared by length of ICU stay (LOS), need for renal replacement therapy and 28-day mortality. Predictive performance and time between prediction and diagnosis were calculated. Results: Of 2492 patients in the cohort, 1560 (62.0%) were diagnosed with AKI by KDIGO and 1706 (68.5%) by KeGFR criteria. Disease stages had agreement of kappa = 0.77, with KeGFR sensitivity 93.2%, specificity 73.0% and accuracy 85.7%. Median time to recognition of AKI Stage 1 was 13.2 h faster for KeGFR, and 7.5 h and 5.0 h for Stages 2 and 3. Outcomes revealed a slight difference in LOS and 28-day mortality for Stage 1. Conclusions: Predictive performance of KeGFR combined with UO criteria for diagnosing AKI is excellent. Compared to KDIGO, deterioration of renal function was identified earlier, most prominently for lower stages of AKI. This may shift the actionable window for preventing and mitigating renal insufficiency
Cytotoxic lymphocytes in B-cell chronic lymphocytic leukemia
No full textThe occurrence of cytotoxic lymphocyte subpopulations (i.e., CD 16+, CD57+ and cytotoxic CD 8+) was studied in the peripheral blood of 18 B-cell chronic lymphocytic leukemia (B-CLL) patients. The absolute numbers of CD 57+, CD 16+ and cytotoxic CD 8+ lymphocytes were increased in the peripheral blood of untreated patients as compared with healthy donors, suggesting a causal relation with the accumulation of malignant B-cells. For 5 B-CLL patients and 5 hematological normal donors, the lymphocyte subpopulations in peripheral blood, lymph nodes and bone marrow were determined. A significant immune response was observed in the lymph nodes of the patients, as reflected by the CD 3+ lymphocytes, which were 1.7–27 times larger in the patients lymph nodes than in their peripheral blood and bone marrow. In contrast, with peripheral blood this was mainly caused by an increase in CD 4+ lymphocytes. The CD 57 lymphocytes in the lymph nodes of the patients had abnormal orthogonal light-scattering signals and an abnormal density of CD 57+ receptors in comparison with their peripheral blood CD 57+ lymphocytes or the CD57+ lymphocytes in the peripheral blood, bone marrow and tonsils of the hematological normal donors. This study shows that although a significant increase of cytotoxic lymphocytes in the peripheral blood of B-CLL patients is observed, the actual distributions of the non-malignant lymphocytes can be quite different at the actual tumor sites, i.e., bone marrow and lymph node
The effects of splenic irradiation on lymphocyte subpopulations in chronic B-lymphocytic leukemia
No full textWe describe the effect of splenic irradiation (SI) (0,5–1 Gy weekly) on lymphocyte subpopulations for 7 patients with progressive B chronic B-lymphocytic leukemia (B-CLL). Using specific cellular characteristics we could distinguish normal from abnormal cells. The irradiation resulted in a decrease of lymph node size, reduction in spleen volume and decrease in peripheral blood lymphocytes. The one exception was a patient with a prolymphocytoid transformation of B-CLL. For 3 patients SI had to be interrupted or stopped because of severe cytopenia. Quantitation of malignant B cells and normal T lymphocytes revealed that the total irradiation dose which resulted in a specific decrease of malignant lymphocytes varied from patient to patient. Normal T-cell subpopulations, which were increased before SI, decreased to normal or abnormally low values during SI. In previously untreated patients, natural killer (NK) cell numbers decreased more rapidly than T-cell subpopulations. For 2 patients refractory to chemotherapy an increase of NK cells was observed upon SI
RAM 111
No full textHet project ‘Behoud en onderzoek van archeologische waarden in het Maasdal in het kader van de Maaswerken en de Via Limburg’ richt zich op de archeologische begeleiding van een aantal infrastructurele werken, waarvan de planvormingsfase in het begin van de jaren ’90 van de 20e eeuw begonnen is. De uitvoering speelt zich af in het eerste en tweede decennium van de 21e eeuw. Het project Maaswerken omvat de projecten Grensmaas, Zandmaas en Maasroute. In het kader van de Maaswerken zullen tussen Borgharen en Roosteren (Grensmaas) en tussen Roermond en Ravenstein (Zandmaas) grootschalige ontgrondingen plaats hebben in het winterbed van de Maas. Het zomerbed van de Zandmaas wordt op een aantal plaatsen verdiept en/of verbreed. In het kader van de Maasroute wordt het Julianakanaal verbreed en vinden in het zomerbed van de Maas aanpassingen plaats om de bevaarbaarheid te verbeteren. De benedenstroomse effecten van de Maaswerken reiken tot Hedel ten noorden van ’s-Hertogenbosch. Het project Via Limburg behelst de aanleg van de Rijksweg 73-Zuid, de Rijksweg 74, de N280-Oost en de N293. Tussen Venlo en Maasbracht wordt de Rijksweg 73-Zuid aangelegd met aftakkingen naar Duitsland ter hoogte van Venlo (Rijksweg 74) en Roermond (N280/293). Het Grensmaasproject heeft een Belgische component. De Via Limburg sluit aan op de Duitse Autobahnen.
Wegens het belang van het Maasdal voor de archeologische monumentenzorg is in 1996 door de ROB het project ‘Maasdal’ gestart. Na opstellen van projectplannen in 1997 (Stoepker 1997a, b, c) is in 1998 is een projectteam archeologie, afgekort PTA, vanuit de ROB bij de projectorganisaties Maaswerken en Via Limburg gestationeerd, waarna met de daadwerkelijke archeologische begeleiding van de projecten is begonnen. De ROB stelt als bevoegd gezag de inhoudelijke kaders vast, waarvan het voorliggende beleidsplan er één van is, en het daarop gebaseerde waarderings- en selectiebeleid. De ROB keurt programma’s van eisen goed en ziet toe dat werkzaamheden en producten aan de programma’s van eisen voldoen. Tot aan de tweede helft van 2002 verrichtte de ROB ook (binnen de organisatie van Maaswerken en Rijkswaterstaat) het archeologisch projectmanagement. In het kader van de wijzigingen in het archeologisch bestel is het aan de projectbureaus Maaswerken en Rijksweg 73-Zuid overgedragen. Dankzij de in een vroeg stadium tot stand gekomen betrokkenheid was het mogelijk om in de (zeer complexe en langdurige) planvormingsfase op een aantal plaatsen behoud in situ te realiseren, in het bijzonder daar waar archeologische belangen samenvielen met natuurwaarden.
De fase van inventariserend, verkennend onderzoek (in oude terminologie: Aanvullende Archeologische Inventarisatie, afgekort AAI) vond in de jaren 1998 – 2002 plaats. Wegens de dynamiek van het project zijn er regelmatig plangebieden afgevallen of bijgekomen. Hoewel in de provinciale wegen en enkele kleine, ‘nagekomen’ gebieden in de Maaswerken nog inventarisaties moeten plaats vinden, kan gezegd worden dat anno 2003 de fase van archeologische inventarisatie is voltooid. In de Maaswerken vindt het waarderend onderzoek in 2003 en 2004 plaats. In de Rijksweg 73-Zuid is dat al eerder begonnen. Ook de fase van definitief onderzoek en uitvoeringsbegeleiding is in de Rijksweg 73-Zuid al ingetreden. Uitvoeringsbegeleiding bij de Maaswerken heeft in enkele proefprojecten plaats gehad.
Deze publicatie geeft een samenvatting en een evaluatie van het verkennend onderzoek en bevat het geactualiseerde onderzoekskader (wetenschappelijk beleidsplan) dat op grond hiervan opgesteld is
Prehistoric Settlement Patterns around the southern North Sea
No full textEen compilatie van artikelen, opgedragen aan Prof. Dr. P.J.R. Modderman. De artikelen zijn afkomstig van een colloquium dat ter zijner ere gehouden werd. Het thema van het colloquium was "Prehistoric Settlement Patterns around the southern North Sea"
Two-armed molecular receptors : peptide recognition and vesicle formation driven by selective non-covalent interactions
No full textThis thesis presents examples for applying encoded combinatorial chemistry to trace molecular interactions between two-armed receptors and peptidic substrates that could have not been predicted by conventional means. Starting from these selective non-covalent interactions, applications, like supramolecular self-assembly, were investigated in organic and aqueous media. In the first part the synthesis of macrocyclic diketopiperazine receptors and their binding properties towards peptides is described. Combinatorial on-bead studies showed that both macrocyclization of the receptor and choice of the linker-type lead to significant changes in the binding properties compared to their flexible open-chain parent diketopiperazine receptors. Macrocyclization rigidifies the receptor and should induce a higher preorganisation. Thus, the conformations of the macrocyclic receptors were expected to differ from the open-chain diketopiperazine receptor prototype. Binding studies revealed that macrocyclization led not only to lower binding selectivities but also lower affinities toward peptidic guest compared to the open-chain parent receptors. Thus, the flexibility of the open-chain receptor allows the arms to better adjust to a peptidic guest and can be beneficial for selective and higher binding. The second part describes the development of a new class of two-armed receptors consisting of a rigid carbazole backbone and peptidic side-chains which allow for structural as well as functional variations. Compared to the diketopiperazine template, a third functionality is present and allows for attachment of a dye, polymer chain or resin, at the opposite site of the recognition modules. Combinatorial binding studies and solid phase binding assays showed that these carbazole receptors interact with certain tripeptides, in organic solvents, with sequence selectivities and binding affinities that are comparable to
those of diketopiperazine receptors. These two-armed receptors have been the basis for the
design of receptor libraries to identify selective receptors for interesting peptidic and nonpeptidic
substrates.
In the third part, selective non-covalent interactions between a diketopiperazine
receptor and peptide-PEG conjugates were used to induce the assembly of vesicles in
aqueous solution. The vesicles were analysed by a combination of light scattering, electron
transmission and atomic force microscopy as well as surface pressure measurements. Vesicle
formation was found to be independent of the ratio of receptor to ligand and relies upon
selective receptor-peptide interactions. Other peptide-PEG conjugates did not assemble into
vesicular structures when mixed with the receptor
Discrimination of human cytotoxic lymphocytes from regulatory and B-lymphocytes by orthogonal light scattering
No full textLight scattering properties of human lymphocyte subpopulations selected by immunofluorescence were studied with a flow cytometer. Regulatory and B-lymphocytes showed a low orthogonal light scatter signal, whereas cytotoxic lymphocytes identified with leu-7, leu-11 and leu-15 revealed a large orthogonal light scatter signal. Two populations in light scatter histograms could be observed with monoclonal antibodies directed against determinants present on both regulatory and cytotoxic lymphocytes. By analysis of the lymphocytes of 16 individuals we found a linear relation between the number of cells with a large orthogonal light scattering and the number of cytotoxic lymphocytes identified with leu-7, leu-11 and leu-15. These observations demonstrate physical differences between cytotoxic lymphocytes and regulatory and B lymphocytes. Moreover, the results suggest a method to estimate the amount of cytotoxic lymphocytes without using monoclonal antibodies
Abnormal distribution of CD8 subpopulation in B-chronic lymphocytic leukemia identified by flow cytometry
No full textWe studied the occurrence of T-cell subpopulations for patients with B-cell chronic lymphocytic leukemia. The CD8+ population was divided into CD8+ suppressor (CD8a+) and CD8+ cytotoxic (CD8b+) lymphocytes using difference in orthogonal light scattering. Average CD4+/CD8+ratios determined for all patients were decreased. For individual patients this sometimes was not true. In contrast CD4+/CD8a+ ratios were markedly increased in all individual patients. The CD8+ lymphocytes appeared to consist mainly of CD8b+lymphocytes. Moreover the CD8b+/CD8+ ratio correlated with clinical stage: untreated patients (stage 0 of Rai) have smaller CD8b+/CD8+ ratios than patients with advanced stages of Rai
Experimental and model investigations of bleaching and saturation of fluorescence in flow cytometry
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