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1.
Soft Matter ; 20(3): 484-494, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-37842771

RESUMO

Understanding and controlling microbial adhesion is a critical challenge in biomedical research, given the profound impact of bacterial infections on global health. Many facets of bacterial adhesion, including the distribution of adhesion forces across the cell wall, remain poorly understood. While a recent 'patchy colloid' model has shed light on adhesion in Gram-negative Escherichia coli cells, a corresponding model for Gram-positive cells has been elusive. In this study, we employ single cell force spectroscopy to investigate the adhesion force of Staphylococcus aureus. Normally, only one contact point of the entire bacterial surface is measured. However, by using a sine-shaped surface and recording force-distance curves along a path perpendicular to the rippled structures, we can characterize almost a hemisphere of one and the same bacterium. This unique approach allows us to study a greater number of contact points between the bacterium and the surface compared to conventional flat substrata. Distributed over the bacterial surface, we identify sites of higher and lower adhesion, which we call 'patchy adhesion', reminiscent of the patchy colloid model. The experimental results show that only some cells exhibit particularly strong adhesion at certain locations. To gain a better understanding of these locations, a geometric model of the bacterial cell surface was created. The experimental results were best reproduced by a model that features a few (5-6) particularly strong adhesion sites (diameter about 250 nm) that are widely distributed over the cell surface. Within the simulated patches, the number of molecules or their individual adhesive strength is increased. A more detailed comparison shows that simple geometric considerations for interacting molecules are not sufficient, but rather strong angle-dependent molecule-substratum interactions are required. We discuss the implications of our results for the development of new materials and the design and analysis of future studies.


Assuntos
Aderência Bacteriana , Staphylococcus aureus , Propriedades de Superfície , Microscopia de Força Atômica/métodos , Parede Celular , Bactérias , Coloides
2.
Naturwissenschaften ; 111(2): 15, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38478046

RESUMO

In Earth's history warm and cold periods have alternated. Especially, during the Pleistocene, the alternation between these different climatic conditions has led to frequent range expansions and retractions of many species: while thermophilic species dispersed during warm periods, cold adapted species retracted to cold refugia and vice versa. After the last Pleistocene cycle many cold adapted taxa found refuges in relict habitats in mountain ranges. One example for such a cold adapted relict is the flightless snow fly Chionea araneoides (Dalman, 1816). It can be found in lower mountain ranges of Central Europe exclusively in stone runs and stony accumulations which provide cold microclimates. Imagines develop only in winter. They have strongly restricted ranges and hence experienced strong isolation predicting that local populations may show local adaptation and hence also genetic differentiation. We investigated this for several middle mountain ranges of Germany using the COI barcoding gene. Our analyses revealed two distinct lineages, one in the Bavarian Forest and a second one in all other more northern locations up to Scandinavia. These lineages likely go back to post-Pleistocene isolation and should be studied in more detail in the future, also to confirm the taxonomic status of both lineages. Further, we confirmed former records of the species for Germany and report new records for the federal states of Saxony, Lower Saxony, Saxony-Anhalt and Thuringia. Finally, we provide the first evidence of two types of males for the species, a small and a larger male type.


Assuntos
Dípteros , Masculino , Animais , Filogenia , Dípteros/genética , Gelo , Variação Genética , Neve
3.
Z Geburtshilfe Neonatol ; 228(3): 270-277, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38242148

RESUMO

Accidental hypothermia in mature neonates requiring hospitalization is a clinical complication that has not been studied in detail. In the present study, the effect of accidental hypothermia on common morbidity in neonates in the postnatal period was investigated. We did temperature measurements in 616 mature neonates after birth, after transfer to the maternity ward and at check-up at age of 48-72 hours of life. Additionally, nurses checked temperature until discharge at every diaper change in 302 of all included neonates who were small for gestational age (SGA) or whose mothers had green fluid or premature rupture of membranes (PROM). We investigated if there was a correlation between infection, hyperbilirubinemia, hypoglycemia, SGA, gestational diabetes, PROM, green amniotic fluid, positive GBS status of the mother, and accidental hypothermia in the first 48-72 hours of life. Mature neonates showed transient accidental hypothermia in the first 24 hours of life. No significant correlation between infection (p=0.571), hyperbilirubinemia (p=0.837), hypoglycemia (p=0.072), and accidental hypothermia could be seen. There was a significant correlation between SGA (p=0.020), PROM (p=0.008), and accidental hypothermia, while hyperthermia was associated with infection (p=0.009) and green amniotic fluid (p=0.004). SGA and PROM represent perinatal risk factors for postnatal transient accidental hypothermia in mature neonates. Increased morbidity or mortality associated with postnatal accidental hypothermia has not been demonstrated.Akzidentelle Hypothermie bei Reifgeborenen, die einer Hospitalisierung bedürfen, ist eine bisher nicht näher analysierte klinische Komplikation. In der vorliegenden Arbeit wurde die Abhängigkeit einer akzidentellen Hypothermie von typischen Erkrankungen der Postnatalperiode untersucht. Wir führten bei 616 Reifgeborenen Temperaturmessungen nach Geburt, nach Verlegung auf die Wochenstation und bei der Vorsorgeuntersuchung U2 durch. Zusätzlich kontrollierten wir bei 302 der 616 Neugeborenen mit Small for gestational age (SGA), grünem Fruchtwasser oder vorzeitigem Blasensprung (PROM) die Temperatur bei jedem Windelwechsel bis zur Entlassung. Wir untersuchten, ob es einen Zusammenhang zwischen Infektion, Hyperbilirubinämie, Hypoglykämie, SGA, Gestationsdiabetes, PROM, grünem Fruchtwasser, positivem GBS-Status der Mutter und akzidenteller Auskühlung innerhalb der ersten 48-72 Lebensstunden gab. Reifgeborene zeigten in den ersten 24 Lebensstunden transiente akzidentelle Hypothermien. Es konnte kein signifikanter Zusammenhang zwischen Infektion (P=0.571), Hyperbilirubinämie (p=0.837), Hypoglykämie (p=0.072) und akzidenteller Hypothermie festgestellt werden. Es bestand ein signifikanter Zusammenhang zwischen SGA (p=0.020), PROM (p=0.008) und akzidenteller Hypothermie, während Hyperthermie war mit Infektion (p=0.009) und grünem Fruchtwasser (p=0.004) assoziiert war. SGA und PROM stellen perinatale Risikofaktoren für postnatale transiente, akzidentelle Hypothermien bei Reifgeborenen dar. Eine erhöhte Morbidiät bzw. Mortalität im Zusammenhang mit postnataler akzidenteller Hypothermie konnte nicht nachgewiesen werden.


Assuntos
Hipotermia , Humanos , Hipotermia/mortalidade , Recém-Nascido , Feminino , Masculino , Fatores de Risco , Alemanha/epidemiologia , Mortalidade Infantil , Taxa de Sobrevida , Comorbidade , Doenças do Recém-Nascido/mortalidade , Recém-Nascido Pequeno para a Idade Gestacional
4.
Nat Mater ; 21(4): 423-429, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35190656

RESUMO

Charge neutrality and their expected itinerant nature makes excitons potential transmitters of information. However, exciton mobility remains inaccessible to traditional optical experiments that only create and detect excitons with negligible momentum. Here, using angle-resolved photoemission spectroscopy, we detect dispersing excitons in the quasi-one-dimensional metallic trichalcogenide, TaSe3. The low density of conduction electrons and the low dimensionality in TaSe3 combined with a polaronic renormalization of the conduction band and the poorly screened interaction between these polarons and photo-induced valence holes leads to various excitonic bound states that we interpret as intrachain and interchain excitons, and possibly trions. The thresholds for the formation of a photo-hole together with an exciton appear as side valence bands with dispersions nearly parallel to the main valence band, but shifted to lower excitation energies. The energy separation between side and main valence bands can be controlled by surface doping, enabling the tuning of certain exciton properties.


Assuntos
Elétrons
5.
Vet Res ; 54(1): 84, 2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37773068

RESUMO

Prion diseases, including chronic wasting disease (CWD) in cervids, are fatal neurodegenerative disorders caused by the misfolding of cellular prion proteins. CWD is known to spread among captive and free-ranging deer in North America. In 2016, an outbreak of contagious CWD was detected among wild reindeer in Norway, marking the first occurrence of the disease in Europe. Additionally, new sporadic forms of CWD have been discovered in red deer in Norway and moose in Fennoscandia. We used serial protein misfolding cyclic amplification to study the ability of Norwegian prion isolates from reindeer, red deer, and moose (two isolates), as well as experimental classical scrapie from sheep, to convert a panel of 16 brain homogenates (substrates) from six different species with various prion protein genotypes. The reindeer CWD isolate successfully converted substrates from all species except goats. The red deer isolate failed to convert sheep and goat substrates but exhibited amplification in all cervid substrates. The two moose isolates demonstrated lower conversion efficacies. The wild type isolate propagated in all moose substrates and in the wild type red deer substrate, while the other isolate only converted two of the moose substrates. The experimental classical scrapie isolate was successfully propagated in substrates from all species tested. Thus, reindeer CWD and classical sheep scrapie isolates were similarly propagated in substrates from different species, suggesting the potential for spillover of these contagious diseases. Furthermore, the roe deer substrate supported conversion of three isolates suggesting that this species may be vulnerable to prion disease.


Assuntos
Cervos , Doenças das Cabras , Doenças Priônicas , Príons , Rena , Scrapie , Doenças dos Ovinos , Doença de Emaciação Crônica , Animais , Ovinos , Príons/genética , Rena/metabolismo , Doenças Priônicas/veterinária , Proteínas Priônicas/genética , Proteínas Priônicas/metabolismo , Doença de Emaciação Crônica/genética , Noruega/epidemiologia , Cabras/metabolismo
6.
BMC Surg ; 23(1): 4, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36624485

RESUMO

BACKGROUND: Computer Assisted Design and Computer Assisted Manufacturing (CAD/CAM) have revolutionized oncologic surgery of the head and neck. A multitude of benefits of this technique has been described, but there are only few reports of donor site comorbidity following CAD/CAM surgery. METHODS: This study investigated comorbidity of the hip following deep circumflex iliac artery (DCIA) graft raising using CAD/CAM techniques. A cross-sectional examination was performed to determine range of motion, muscle strength and nerve disturbances. Furthermore, correlations between graft volume and skin incision length with postoperative donor site morbidity were assessed using Spearman's rank correlation, linear regression and analysis of variance (ANOVA). RESULTS: Fifteen patients with a mean graft volume of 21.2 ± 5.7 cm3 and a mean incision length of 228.0 ± 30.0 mm were included. Patients reported of noticeable physical limitations in daily life activities (12.3 ± 11.9 weeks) and athletic activities (38.4 ± 40.0 weeks in mean) following surgery. Graft volume significantly correlated with the duration of the use of walking aids (R = 0.57; p = 0.033) and impairment in daily life activities (R = 0.65; p = 0.012). The length of the scar of the donor-site showed a statistically significant association with postoperative iliohypogastric nerve deficits (F = 4.4, p = 0.037). Patients with anaesthaesia of a peripheral cutaneous nerve had a larger mean scar length (280 ± 30.0 mm) than subjects with hypaesthesia (245 ± 10.1 mm) or no complaints (216 ± 27.7 mm). CONCLUSIONS: Despite sophisticated planning options in modern CAD/CAM surgery, comorbidity of the donor site following  iliac graft harvesting is still a problem. This study is the first to investigate comorbidity after DCIA graft raising in a patient group treated exclusively with CAD/CAM techniques. The results indicate that a minimal invasive approach in terms of small graft volumes and small skin incisions could help to reduce postoperative symptomatology. Trial registration Retrospectively registered at the German Clinical Trials Register (DRKS-ID: DRKS00029066); registration date: 23/05/2022.


Assuntos
Cicatriz , Artéria Ilíaca , Humanos , Cicatriz/epidemiologia , Cicatriz/etiologia , Computadores , Estudos Transversais , Artéria Ilíaca/cirurgia , Mandíbula/cirurgia , Morbidade
7.
J Am Chem Soc ; 143(41): 17047-17058, 2021 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-34632780

RESUMO

Dynamic covalent chemistry (DCvC) has emerged as a versatile synthetic tool for devising stable, stimuli-responsive linkers or conjugates. The interplay of binding affinity, association and dissociation constants exhibits a strong influence on the selectivity of the reaction, the conversion rate, as well as the stability in aqueous solutions. Nevertheless, dynamic covalent interactions often exhibit fast binding and fast dissociation events or vice versa, affecting their conversion rates or stabilities. To overcome the limitation in linker design, we reported herein dual responsive dynamic covalent peptide tags combining a pH responsive boronate ester with fast association and dissociation rates, and a redox-active disulfide with slow formation and dissociation rate. Precoordination by boronic acid-catechol interaction improves self-sorting and selectivity in disulfide formation into heterodimers. The resulting bis-peptide conjugate exhibited improved complex stability in aqueous solution and acidic tumor-like extracellular microenvironment. Furthermore, the conjugate responds to pH changes within the physiological range as well as to redox conditions found inside cancer cells. Such tags hold great promise, through cooperative effects, for controlling the stability of bioconjugates under dilution in aqueous media, as well as designing intelligent pharmaceutics that react to distinct biological stimuli in cells.


Assuntos
Ácidos Borônicos
8.
Eur Respir J ; 58(1)2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33419890

RESUMO

BACKGROUND: Data from the INMARK trial were used to investigate the feasibility and validity of home spirometry as a measure of lung function decline in patients with idiopathic pulmonary fibrosis (IPF). METHODS: Subjects with IPF and preserved forced vital capacity (FVC) were randomised to receive nintedanib or placebo for 12 weeks followed by open-label nintedanib for 40 weeks. Clinic spirometry was conducted at baseline and weeks 4, 8, 12, 16, 20, 24, 36 and 52. Subjects were asked to perform home spirometry at least once a week and ideally daily. Correlations between home- and clinic-measured FVC and rates of change in FVC were assessed using Pearson correlation coefficients. RESULTS: In total, 346 subjects were treated. Mean adherence to weekly home spirometry decreased over time but remained above 75% in every 4-week period. Over 52 weeks, mean adherence was 86%. Variability in change from baseline in FVC was greater when measured by home rather than clinic spirometry. Strong correlations were observed between home- and clinic-measured FVC at all time-points (r=0.72-0.84), but correlations between home- and clinic-measured rates of change in FVC were weak (r=0.26 for rate of decline in FVC over 52 weeks). CONCLUSION: Home spirometry was a feasible and valid measure of lung function in patients with IPF and preserved FVC, but estimates of the rate of FVC decline obtained using home spirometry were poorly correlated with those based on clinic spirometry.


Assuntos
Fibrose Pulmonar Idiopática , Humanos , Fibrose Pulmonar Idiopática/diagnóstico , Fibrose Pulmonar Idiopática/tratamento farmacológico , Espirometria , Resultado do Tratamento , Capacidade Vital
9.
J Sleep Res ; 30(4): e13239, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33348471

RESUMO

Sleep spindles benefit declarative memory consolidation and are considered to be a biological marker for general cognitive abilities. However, the impact of sexual hormones and hormonal oral contraceptives (OCs) on these relationships are less clear. Thus, we here investigated the influence of endogenous progesterone levels of naturally cycling women and women using OCs on nocturnal sleep and overnight memory consolidation. Nineteen healthy women using OCs (MAge  = 21.4, SD = 2.1 years) were compared to 43 healthy women with a natural menstrual cycle (follicular phase: n = 16, MAge  = 21.4, SD = 3.1 years; luteal phase: n = 27, MAge  = 22.5, SD = 3.6 years). Sleep spindle density and salivary progesterone were measured during an adaptation and an experimental night. A word pair association task preceding the experimental night followed by two recalls (pre-sleep and post-sleep) was performed to test declarative memory performance. We found that memory performance improved overnight in all women. Interestingly, women using OCs (characterized by a low endogenous progesterone level but with very potent synthetic progestins) and naturally cycling women during the luteal phase (characterized by a high endogenous progesterone level) had a higher fast sleep spindle density compared to naturally cycling women during the follicular phase (characterized by a low endogenous progesterone level). Furthermore, we observed a positive correlation between endogenous progesterone level and fast spindle density in women during the luteal phase. Results suggest that the use of OCs and the menstrual cycle phase affects sleep spindles and therefore should be considered in further studies investigating sleep spindles and cognitive performance.


Assuntos
Anticoncepcionais Orais/farmacologia , Consolidação da Memória/efeitos dos fármacos , Ciclo Menstrual/efeitos dos fármacos , Ciclo Menstrual/psicologia , Sono/efeitos dos fármacos , Feminino , Humanos , Rememoração Mental/efeitos dos fármacos , Adulto Jovem
10.
Nucleic Acids Res ; 47(21): 11430-11440, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31665419

RESUMO

Although group II intron ribozymes are intensively studied the question how structural dynamics affects splicing catalysis has remained elusive. We report for the first time that the group II intron domain 6 exists in a secondary structure equilibrium between a single- and a two-nucleotide bulge conformation, which is directly linked to a switch between sugar puckers of the branch site adenosine. Our study determined a functional sugar pucker equilibrium between the transesterification active C2'-endo conformation of the branch site adenosine in the 1nt bulge and an inactive C3'-endo state in the 2nt bulge fold, allowing the group II intron to switch its activity from the branching to the exon ligation step. Our detailed NMR spectroscopic investigation identified magnesium (II) ions and the branching reaction as regulators of the equilibrium populations. The tuneable secondary structure/sugar pucker equilibrium supports a conformational selection mechanism to up- and downregulate catalytically active and inactive states of the branch site adenosine to orchestrate the multi-step splicing process. The conformational dynamics of group II intron domain 6 is also proposed to be a key aspect for the directionality selection in reversible splicing.


Assuntos
Íntrons/genética , Conformação de Ácido Nucleico , Splicing de RNA/fisiologia , RNA/química , Açúcares/química , Sítios de Ligação , Carboidratos/química , Magnésio/química , Espectroscopia de Ressonância Magnética , RNA/metabolismo , Açúcares/metabolismo
11.
J Oral Maxillofac Surg ; 79(7): 1570-1579, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33675703

RESUMO

PURPOSE: There is no consensus on the impact of red blood cell (RBC) transfusion on patients with oral squamous cell carcinoma (OSCC). The purpose of this study was to investigate the association between RBC transfusions and overall survival (OS) and tumor-free survival (TFS) after operative treatment of OSCC. METHODS: In this retrospective cohort study, all patients treated with primary surgery between 2003 and 2017 because of OSCC were chart reviewed. The occurrence and amount of RBC transfusions (0; 1-3; >3 units) was correlated with OS and TFS by Kaplan-Meier survival and Cox regression analyses. Demographic, clinical, and pathological parameters were also evaluated in order to identify confounding factors. RESULTS: Of 420 patients (243 [57.9%] male) with a mean age of 62.6 years, 67 (16.0%) received RBC transfusion. There were statistically significant (P < .01) differences in 5-year OS respectively TFS in transfused patients for the Kaplan-Meier survival analysis (0 units = 70.6%; [95% confidence interval {CI}: 65.0-75.4%] respectively 63.2% [95% CI: 57.4-68.4%], 1-3 units = 47.2% [95% CI: 29.4-63.1%] respectively 40.6% [95% CI: 24.6-55.95%] and >3 units = 48.9% [95% CI: 20.9-72.1%] respectively 30.5% [95% CI: 8.9-55.8%]). After multivariate adjustments for demographic, clinical, and pathological parameters, RBC transfusion could not be sustained as a significant prognostic factor in OS respectively TFS (1-3 units: hazard ratio = 1.5 [95% CI: 0.7-3.2] respectively 1.3 [95% CI: 0.7-2.6]; >3 units: hazard ratio = 1.2 [95% CI: 0.5 - 3.0] respectively 1.1 [95% CI: 0.5-2.4]). CONCLUSIONS: Although RBC transfusion was not identified as a significant prognostic parameter in multivariate analysis, a clear trend for shorter OS and TFS for transfused patients in univariate and Kaplan-Meier survival analysis could be shown.


Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Neoplasias Bucais , Carcinoma de Células Escamosas/cirurgia , Transfusão de Eritrócitos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Bucais/cirurgia , Estudos Retrospectivos , Carcinoma de Células Escamosas de Cabeça e Pescoço
12.
Proc Natl Acad Sci U S A ; 115(3): E382-E389, 2018 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-29298914

RESUMO

Termination of protein synthesis is triggered by the recognition of a stop codon at the ribosomal A site and is mediated by class I release factors (RFs). Whereas in bacteria, RF1 and RF2 promote termination at UAA/UAG and UAA/UGA stop codons, respectively, eukaryotes only depend on one RF (eRF1) to initiate peptide release at all three stop codons. Based on several structural as well as biochemical studies, interactions between mRNA, tRNA, and rRNA have been proposed to be required for stop codon recognition. In this study, the influence of these interactions was investigated by using chemically modified stop codons. Single functional groups within stop codon nucleotides were substituted to weaken or completely eliminate specific interactions between the respective mRNA and RFs. Our findings provide detailed insight into the recognition mode of bacterial and eukaryotic RFs, thereby revealing the chemical groups of nucleotides that define the identity of stop codons and provide the means to discriminate against noncognate stop codons or UGG sense codons.


Assuntos
Códon de Terminação/genética , Escherichia coli/metabolismo , Fatores de Terminação de Peptídeos/fisiologia , Proteínas de Escherichia coli/metabolismo , Mutagênese Sítio-Dirigida , Nucleotídeos , Terminação Traducional da Cadeia Peptídica , Biossíntese de Proteínas
13.
Nanotechnology ; 31(34): 345203, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32392549

RESUMO

We report on photodetection in deep subwavelength Ge(Sn) nano-islands on Si nano-pillar substrates, in which self-aligned nano-antennas in the Al contact metal are used to enhance light absorption by means of local surface plasmon resonances. The impact of parameters such as substrate doping and device geometry on the measured responsivities are investigated and our experimental results are supported by simulations of the three-dimensional distribution of the electromagnetic fields. Comparatively high optical responsivities of about 0.1 A W-1 are observed as a consequence of the excitation of localized surface plasmons, making our nano-island photodetectors interesting for applications in which size reduction is essential.

14.
Z Geburtshilfe Neonatol ; 224(5): 281-288, 2020 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-32698223

RESUMO

BACKGROUND: The quality guideline for care delivery to preterm and mature infants (QFR-RL) places high demands on perinatal centers. In this analysis, the degree of fulfillment was determined. Additionally, care delivery to further patient groups and sufficient nursing staff capacity for care delivery to imminent preterm infants (FG) were evaluated. METHODS: A network of 4 perinatal centers (level 1) with about 10,000 births per year supplied the data on the ratio of 1:1/1:2-care infants, patients per nurse, and nursing staff capacity. This data was statistically evaluated by center, shift, and week day over a period of 5 months for compliance with QFR-RL and DGPM recommendations. Furthermore, imminent preterm infants were recorded and compared with available nursing staff capacity. RESULTS: In total, the QFR-RL was fulfilled in 88% of shifts (n=1,584). Only one center reached the required 95%. The degree of fulfillment and the number of staff nurses declined from late to night shifts (p<0.001). The ratio of 1:1-care infants was significantly higher when demands were not fulfilled (p<0.001). Only 14.1% of imminent preterm infants could have been attended in accordance with the QFR-RL. CONCLUSION: 1:1 care as well as lower nurse staffing in late and night shifts lead to non-fulfillment of requirements and poorer care delivery to other intensive care patients. This was also reflected in the lower degree of fulfillment of DGPM recommendations. Sufficient nursing staff capacity was rare with the consequence that it was almost impossible to deliver care to imminent preterm infants per the guideline.


Assuntos
Recém-Nascido Prematuro , Assistência Perinatal , Criança , Atenção à Saúde , Feminino , Humanos , Lactente , Recém-Nascido , Gravidez
15.
Nucleic Acids Res ; 45(15): 9178-9192, 2017 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-28911104

RESUMO

We report the synthesis of atom-specifically 13C-modified building blocks that can be incorporated into DNA via solid phase synthesis to facilitate investigations on structural and dynamic features via NMR spectroscopy. In detail, 6-13C-modified pyrimidine and 8-13C purine DNA phosphoramidites were synthesized and incorporated into a polypurine tract DNA/RNA hybrid duplex to showcase the facile resonance assignment using site-specific labeling. We also addressed micro- to millisecond dynamics in the mini-cTAR DNA. This DNA is involved in the HIV replication cycle and our data points toward an exchange process in the lower stem of the hairpin that is up-regulated in the presence of the HIV-1 nucleocapsid protein 7. As another example, we picked a G-quadruplex that was earlier shown to exist in two folds. Using site-specific 8-13C-2'deoxyguanosine labeling we were able to verify the slow exchange between the two forms on the chemical shift time scale. In a real-time NMR experiment the re-equilibration of the fold distribution after a T-jump could be monitored yielding a rate of 0.012 min-1. Finally, we used 13C-ZZ-exchange spectroscopy to characterize the kinetics between two stacked X-conformers of a Holliday junction mimic. At 25°C, the refolding process was found to occur at a forward rate constant of 3.1 s-1 and with a backward rate constant of 10.6 s-1.


Assuntos
DNA Cruciforme/química , DNA/química , Repetição Terminal Longa de HIV , Proteínas do Nucleocapsídeo/química , Compostos Organofosforados/química , RNA/química , Pareamento de Bases , Isótopos de Carbono , Quadruplex G , HIV-1/química , Marcação por Isótopo , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Mimetismo Molecular , Conformação de Ácido Nucleico , Compostos Organofosforados/síntese química , Técnicas de Síntese em Fase Sólida
16.
Chemistry ; 24(71): 18903-18906, 2018 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-30300940

RESUMO

Watson-Crick like G-U mismatches with tautomeric Genol or Uenol bases can evade fidelity checkpoints and thereby contribute to translational errors. The 5-oxyacetic acid uridine (cmo5 U) modification is a base modification at the wobble position on tRNAs and is presumed to expand the decoding capability of tRNA at this position by forming Watson-Crick like cmo5 Uenol -G mismatches. A detailed investigation on the influence of the cmo5 U modification on structural and dynamic features of RNA was carried out by using solution NMR spectroscopy and UV melting curve analysis. The introduction of a stable isotope labeled variant of the cmo5 U modifier allowed the application of relaxation dispersion NMR to probe the potentially formed Watson-Crick like cmo5 Uenol -G base pair. Surprisingly, we find that at neutral pH, the modification promotes transient formation of anionic Watson-Crick like cmo5 U- -G, and not enolic base pairs. Our results suggest that recoding is mediated by an anionic Watson-Crick like species, as well as bring an interesting aspect of naturally occurring RNA modifications into focus-the fine tuning of nucleobase properties leading to modulation of the RNA structural landscape by adoption of alternative base pairing patterns.

17.
J Sep Sci ; 41(3): 704-712, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29134782

RESUMO

We present a novel method for the quantitative determination of the clean-up efficiency to provide a calculated parameter for peak purity through iterative fitting in conjunction with design of experiments. Rosemary extracts were used and analyzed before and after solid-phase extraction using a self-fabricated mixed-mode sorbent based on poly(N-vinylimidazole/ethylene glycol dimethacrylate). Optimization was performed by variation of washing steps using a full three-level factorial design and response surface methodology. Separation efficiency of rosmarinic acid from interfering compounds was calculated using an iterative fit of Gaussian-like signals and quantifications were performed by the separate integration of the two interfering peak areas. Results and recoveries were analyzed using Design-Expert® software and revealed significant differences between the washing steps. Optimized parameters were considered and used for all further experiments. Furthermore, the solid-phase extraction procedure was tested and compared with commercial available sorbents. In contrast to generic protocols of the manufacturers, the optimized procedure showed excellent recoveries and clean-up rates for the polymer with ion exchange properties. Finally, rosemary extracts from different manufacturing areas and application types were studied to verify the developed method for its applicability. The cleaned-up extracts were analyzed by liquid chromatography with tandem mass spectrometry for detailed compound evaluation to exclude any interference from coeluting molecules.


Assuntos
Cromatografia Líquida de Alta Pressão , Cinamatos/análise , Depsídeos/análise , Extratos Vegetais/análise , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Imidazóis , Metacrilatos , Modelos Estatísticos , Distribuição Normal , Óleos Voláteis/análise , Polímeros , Reprodutibilidade dos Testes , Ácido Rosmarínico
18.
Oecologia ; 182(4): 1141-1150, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27589972

RESUMO

Semi-natural grasslands in Europe are insect biodiversity hotspots and important source habitats delivering ecosystem services to adjacent agricultural land by species spillover. However, this spillover might also occur in the opposite direction, affecting the diversity of semi-natural grasslands. This opposite spillover has got little attention in scientific literature even though generalist species penetrating into the grasslands can affect local biotic interactions, community composition and the conservation value of grassland habitats. In this study, we examined spillover effects from two different adjacent habitat types on carabid beetle assemblages in 20 semi-natural calcareous grasslands. The grasslands were either adjacent to a cereal crop field or to a coniferous forest. We found distinct differences in carabid beetle assemblages in calcareous grasslands depending on adjacent habitat type. Species richness and activity density were higher, but the evenness was lower in calcareous grasslands adjacent to crop fields compared with calcareous grasslands adjacent to coniferous forests. Further, we found a strong spillover of carabid beetles from adjacent crop fields after crop harvest, which may result in transiently increased predation pressure and resource competition in calcareous grasslands. Our results highlight that species composition, diversity and presumably ecosystem functions within semi-natural habitats are affected by the type and management of surrounding habitats. This needs to be considered by nature conservation measures, which aim to protect the unique insect communities of semi-natural European grasslands.


Assuntos
Besouros , Pradaria , Animais , Biodiversidade , Ecossistema , Florestas
19.
Angew Chem Int Ed Engl ; 55(39): 12008-12, 2016 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-27533469

RESUMO

In this work an improved stable isotope labeling protocol for nucleic acids is introduced. The novel building blocks eliminate/minimize homonuclear (13) C and (1) H scalar couplings thus allowing proton relaxation dispersion (RD) experiments to report accurately on the chemical exchange of nucleic acids. Using site-specific (2) H and (13) C labeling, spin topologies are introduced into DNA and RNA that make (1) H relaxation dispersion experiments applicable in a straightforward manner. The novel RNA/DNA building blocks were successfully incorporated into two nucleic acids. The A-site RNA was previously shown to undergo a two site exchange process in the micro- to millisecond time regime. Using proton relaxation dispersion experiments the exchange parameters determined earlier could be recapitulated, thus validating the proposed approach. We further investigated the dynamics of the cTAR DNA, a DNA transcript that is involved in the viral replication cycle of HIV-1. Again, an exchange process could be characterized and quantified. This shows the general applicablility of the novel labeling scheme for (1) H RD experiments of nucleic acids.


Assuntos
DNA/química , Marcação por Isótopo/métodos , Ressonância Magnética Nuclear Biomolecular/métodos , RNA/química , Sequência de Bases , Conformação de Ácido Nucleico , Prótons
20.
Exp Cell Res ; 324(2): 157-71, 2014 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-24726914

RESUMO

This study highlights the highly dynamic nature of SULF1/SULF2 splice variants in different human pancreatic cancers that regulate the activities of multiple cell signalling pathways in development and disease. Most pancreatic tumours expressed variable levels of both SULF1 and SULF2 variants including some expression during inflammation and pancreatitis. Many ductal and centro-acinar cell-derived pancreatic tumours are known to evolve into lethal pancreatic ductal adenocarcinomas but the present study also detected different stages of such tumour progression in the same tissue biopsies of not only acinar cell origin but also islet cell-derived cancers. The examination of caerulein-induced pancreatic injury and tumorigenesis in a Kras-driven mouse model confirmed the activation and gradual increase of SULF1/SULF2 variants during pancreatitis and tumorigenesis but with reduced levels in Stat3 conditional knockout mice with reduced inflammation. The significance of differential spatial and temporal patterns of specific SULF1/SULF2 splice variant expression during cancer growth became further apparent from their differential stimulatory or inhibitory effects on growth factor activities, tumour growth and angiogenesis not only during in vitro but also in vivo growth thus providing possible novel therapeutic targets.


Assuntos
Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Sulfotransferases/fisiologia , Carga Tumoral/genética , Adulto , Animais , Embrião de Galinha , Progressão da Doença , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Isoenzimas/genética , Isoenzimas/fisiologia , Camundongos , Camundongos Knockout , Neoplasias Pancreáticas/metabolismo , Sulfatases , Sulfotransferases/genética , Células Tumorais Cultivadas , Neoplasias Pancreáticas
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