Die chromosomalen Veränderungen in der Rattenleber während der krebsigen Entartung nach Verfütterung von Buttergelb

Zusammenfassung Erwachsene Ratten wurden mit 4-Dimethylaminoazobenzol (“Buttergelb”) gefüttert und die Mitosen der Leberkerne nach Aufnahme verschiedener Buttergelbmengen (200–1020 mg) auf Chromosomenzahlen und Mitoseanomalien hin untersucht. Um mehr Teilungsstadien zu erhalten, wurde die Leber 48 Std vor der Fixierung partiell hepatektomiert. Auch in buttergelbbehandelten Rattenlebern ist ein Mitosemuster vorhanden, dessen Zusammensetzung sich w?hrend der Buttergelbbehandlung in charakteristischer Weise ver?ndert: Mit steigender Buttergelbdosis nehmen die diploiden Mitosen stark ab (von 44% auf 10%), die aneuploiden Stadien stark zu (von 13% auf 60%). Die Ver?nderungen vom euploiden (diploiden) zum aneuploiden Mitosemuster gehen sprunghaft vor sich, wobei die erste Reaktionsschwelle nach 300 mg Buttergelbaufnahme liegt. Bei 939 untersuchten aneuploiden Metaphasen finden sich Chromosomenzahlen zwischen 6 und 192. Von den in diesem Bereich enthaltenen 178 m?glichen aneuploiden Zahlen sind nur 50 realisiert. Die Zahlen 27, 33, 36, 48, 54, 69, 75, 96 sind dabei besonders h?ufig (78,5% aller aneuploiden Metaphasen). Mit steigender Buttergelbdosis kommen zus?tzlich zu den bereits bevorzugt auftretenden vier aneuploiden Zahlen der unbehandelten Leber weitere aneuploide Zahlen als bevorzugt hinzu, deren H?ufigkeit mit steigender Dosis ansteigt. Ferner treten neue aneuploide, nicht bevorzugte Chromosomenzahlen auf. Sowohl für die neuauftretenden, bevorzugten wie nicht bevorzugten Klassen ist eine an bestimmte Buttergelbdosen gebundene Entstehung charakteristisch. Mit 4 Textabbildungen     

A controlled trial of glucagon in acute experimental pancreatitis in rats

Acute pancreatitis was induced in 245 rats by retrograde instillation of Na-taurocholate into the pancreatic duct. Mortality rate in animals treated 6-hourly with glucagon (1 mg/kg) after induction of pancreatitis was 50% as compared to 30% deaths in the controls treated with 0,9% NaCl (chi2-test: p less than 0,05). Mortality rate in animals treated 6-hourly with the same dose of glucagon before induction of pancreatitis was 36,5% as compared to 28% deaths in the corresponding controls (chi2-test: p greater than 0,05). Glucagon in lower doses (0,1-0,5 mg/kg every 6 hours) did not alter mortality rates as compared to animals treated with 0,9% NaCl. 2. A nonletal form of pancreatitis was induced in 26 rats by ligation of the pancreatic duct. Injection of glucagon (1 mg/kg) seemed to suppress amylase activities in blood for a short period of appr. 1 hour. However, 7 and 9 hours after induction of pancreatitis, amylase activities were significantly higher in animals treated one or two times with glucagon as compared to untreated controls. It is concluded that glucagon in the high dose of 1-4 mg/kg/24 hours does not only not influence the course of acute experimental pancreatitis in rats but can even deteriorate it.     

Adaptive differentiation and rapid evolution of a soil bacterium along a climate gradient

Microbial community responses to environmental change are largely associated with ecological processes; however, the potential for microbes to rapidly evolve and adapt remains relatively unexplored in natural environments. To assess how ecological and evolutionary processes simultaneously alter the genetic diversity of a microbiome, we conducted two concurrent experiments in the leaf litter layer of soil over 18 mo across a climate gradient in Southern California. In the first experiment, we reciprocally transplanted microbial communities from five sites to test whether ecological shifts in ecotypes of the abundant bacterium, Curtobacterium, corresponded to past adaptive differentiation. In the transplanted communities, ecotypes converged toward that of the native communities growing on a common litter substrate. Moreover, these shifts were correlated with community-weighted mean trait values of the Curtobacterium ecotypes, indicating that some of the trait variation among ecotypes could be explained by local adaptation to climate conditions. In the second experiment, we transplanted an isogenic Curtobacterium strain and tracked genomic mutations associated with the sites across the same climate gradient. Using a combination of genomic and metagenomic approaches, we identified a variety of nonrandom, parallel mutations associated with transplantation, including mutations in genes related to nutrient acquisition, stress response, and exopolysaccharide production. Together, the field experiments demonstrate how both demographic shifts of previously adapted ecotypes and contemporary evolution can alter the diversity of a soil microbiome on the same timescale.

Microbial communities respond quickly to environmental change (1, 2). These responses are typically associated with ecological processes; however, the potential for microbes to evolve and adapt to changes in the environment on ecological timescales remains largely unexplored in natural ecosystems. While evolutionary processes are typically considered over longer timescales, the short generation times, large populations, and high mutation rates indicative of microorganisms may allow for rapid adaptation. Laboratory studies have repeatedly demonstrated rapid evolution of bacterial populations (3) with consequences for organismal physiology (4), yet it remains unclear how these in vitro studies extend to in situ communities (5).Both ecological and evolutionary processes likely contribute simultaneously (6, 7) to the response of a microbiome to changing environmental conditions (8). However, separating these processes for bacteria can be difficult as they occur along a continuum of temporal and genetic scales. In terms of ecological processes, microbiome composition can respond demographically, as selective forces promote the growth and survival of differentially adapted taxa within the bacterial community. Certainly, many studies have observed such shifts in taxonomic composition of 16S ribosomal RNA (rRNA)–defined taxa in response to simulated global changes (9), and these responses are considered an ecological process (e.g., species sorting). Few examples, however, link these responses to trait differences among bacterial taxa (10–13), precluding direct insights into whether these ecological shifts are due to adaptive differentiation among taxa as a result of past evolutionary divergence. Concurrently, the same selective forces can also shift the abundance of conspecific strains and alter the allele frequencies of preexisting genetic variation, which at this genetic scale is defined as an evolutionary process (14). Finally, evolution through de novo mutation can provide a new source of genetic variation that may allow for further adaptation to environmental change.In this study, we aimed to capture this continuum of ecological and evolutionary processes that together produce the response of a microbiome’s diversity to environmental change (Fig. 1A). Studying evolution in microbial communities in situ, however, is challenging. For one, variation in highly conserved marker genes used in many microbiome studies (e.g., 16S rRNA) represents distant evolutionary divergences, and thus these regions are too conserved to detect locally adapted lineages (11, 12, 15), let alone recent evolutionary change within communities (16). To overcome this limitation, studies have leveraged shotgun metagenomic data (17, 18) and genome sequences of co-occurring, closely related strains (19, 20) to characterize evolutionary processes (e.g., recombination and gene flow) structuring the genetic diversity of bacterial lineages. However, these studies are also limited by an inherent challenge in microbiome research: delineating population boundaries, the fundamental unit of evolution. While progress has been made in defining microbial species (21–23), the high genetic heterogeneity within diverse microbial communities, such as soils, convolute the boundaries of the fine-scale patterns of genetic diversity within microbial taxonomic units (12). For instance, metagenome-assembled genomes are often composed of a composite of strains forming a large population of mosaic genomes (24) that may not fully capture the diversity of the local population (25). As such, it remains difficult to study evolutionary rates within microbial communities (however, see refs. 26, 27), and the extent and time scale at which evolutionary processes contribute to both standing and new genetic variation relative to ecological processes.Open in a separate windowFig. 1.Microbial community transplant experiment. (A) Changes in microbial community composition can be due to a continuum of ecological and evolutionary processes. For instance, shifts in standing genetic variation can be attributed to both ecological and evolutionary processes depending on the level of biological resolution, while de novo mutations can be a result from evolutionary adaptation. (B) A schematic of the two parallel transplant experiments at the community and strain level. Inoculated litterbags were transplanted to all sites along an elevation gradient that covaried in temperature and precipitation. Site codes: D=Desert; Sc=Scrubland; G=Grassland; P=Pine-Oak; S=Subalpine.Here, we asked the following question: can we characterize the ecological and evolutionary processes that are contributing concurrently to the response of a soil bacterial community to a changing environment? To answer this question, we utilized a field-based experimental approach to quantify the influence of both ecological and evolutionary processes on one focal soil bacterium in its natural environment, the genus Curtobacterium (28). Specifically, we transplanted the bacterium across an elevation gradient on a common resource (leaf litter) substrate (29) to assess its response to new climates in two parallel experiments over the same 18 mo time period (Fig. 1B). In both experiments, we used microbial cages [nylon mesh bags that allow for nutrient transport (30)] to manipulate microbial composition while restricting microbial migration to eliminate the introduction of new alleles and/or variants from dispersal (31). A reciprocal transplant design allowed for direct testing of microbial adaptation to abiotic conditions (i.e., moisture and temperature) in a natural setting.In the first experiment, we conducted a reciprocal transplant of the entire microbial community (32) and tracked the ecological response of Curtobacterium ecotypes (33). A bacterial ecotype is defined as highly clustered genotypic and phenotypic strains occupying the same ecological niche, somewhat equivalent to a eukaryotic species (34). To test the hypothesis that Curtobacterium ecotypes are locally adapted to their climate conditions, we assessed the convergence of ecotype composition in the transplanted communities to that of control communities (those that remained in their native environment; Fig. 1B). We further hypothesized that the demographic shifts were due to differential adaptation to local climates as a result of trait variation among the ecotypes. Thus, we expected that the climate gradient would select for a strong trait–environment relationship (assessed by community-weighted mean (CWM) trait values) as typically observed in plant communities (35, 36).In parallel, we conducted an in situ evolution experiment by transplanting an isogenic Curtobacterium strain across the same gradient to investigate the potential for rapid evolution on the same timescales. We hypothesized that a variety of genomic mutations would be associated with adaptation to local climate conditions. Therefore, we expected fewer genetic changes when the strain was transplanted to its original environment, the midelevation Grassland site, while the extreme sites of the gradient would impose stronger selective pressures resulting in greater genetic changes. We further expected to observe parallel mutations among replicates within a site, which would be indicative of adaptive events (37). Variation in such mutations across sites would suggest selection differences across the climate gradient. Together, the two experiments capture the simultaneous effects of both ecological and evolutionary processes on the response of a soil bacterium to new climates in the field.     

Uric Acid and Cardiovascular Events: A Mendelian Randomization Study

Obesity and diets rich in uric acid–raising components appear to account for the increased prevalence of hyperuricemia in Westernized populations. Prevalence rates of hypertension, diabetes mellitus, CKD, and cardiovascular disease are also increasing. We used Mendelian randomization to examine whether uric acid is an independent and causal cardiovascular risk factor. Serum uric acid was measured in 3315 patients of the Ludwigshafen Risk and Cardiovascular Health Study. We calculated a weighted genetic risk score (GRS) for uric acid concentration based on eight uric acid–regulating single nucleotide polymorphisms. Causal odds ratios and causal hazard ratios (HRs) were calculated using a two-stage regression estimate with the GRS as the instrumental variable to examine associations with cardiometabolic phenotypes (cross-sectional) and mortality (prospectively) by logistic regression and Cox regression, respectively. Our GRS was not consistently associated with any biochemical marker except for uric acid, arguing against pleiotropy. Uric acid was associated with a range of prevalent diseases, including coronary artery disease. Uric acid and the GRS were both associated with cardiovascular death and sudden cardiac death. In a multivariate model adjusted for factors including medication, causal HRs corresponding to each 1-mg/dl increase in genetically predicted uric acid concentration were significant for cardiovascular death (HR, 1.77; 95% confidence interval, 1.12 to 2.81) and sudden cardiac death (HR, 2.41; 95% confidence interval, 1.16 to 5.00). These results suggest that high uric acid is causally related to adverse cardiovascular outcomes, especially sudden cardiac death.     

Effects of in vitro conditions on the survival of Alaria alata mesocercariae

The aim of this study was to determine the effect of different concentrations of table salt (NaCl) and ethanol (v/v) solutions on the viability of Alaria alata mesocercariae. Furthermore, the survival of A. alata mesocercariae during simulated human gastric digestion was evaluated. For this purpose, A. alata mesocercariae migration technique (AMT) was used for the isolation of the parasite from high-positive A. alata mesocercariae meat from wild boar, raccoon, raccoon dog, and badger meat. In total, we have studied the behavior of 582 larvae under different conditions (NaCl, ethanol, and artificial gastric juice) in three independent in vitro experiments. The larvae survived at a NaCl concentration of up to 2.0 % until day 21 with a median survival time of 11 days. At 3.0 % NaCl concentration, the larvae lost their vitality after less than 24 h. In addition, it was found that ethanol concentrations from 8.0 to 70.0 % were effective at reducing survival of A. alata mesocercariae within a short period of time (<1 min). Finally, our studies have revealed that it required 120 min to reliably inactivate all A. alata mesocercariae within HCl-pepsin digestion solution with a pH of 1.5–2.0 at 37 °C. Consequently, the results showed that 3.0 % is the minimum concentration of NaCl in meat products recommended for human consumption because at lower NaCl concentration the parasite survived for a substantial period of time. Finally, the common concentrations of ethanol used for the disinfection of surfaces in household and/or laboratory, are sufficient for the inactivation of A. alata mesocercariae.     

Prolactin and its 16-kDa N-terminal fragment: are higher in patients with precapillary pulmonary hypertension than in a healthy control group

We sought to determine whether patients with precapillary pulmonary hypertension show elevated serum levels of prolactin (PRL) and its 16-kDa N-terminal fragment (16-kDa PRL) and whether there is any correlation to measures of prognosis.Twenty-eight patients with idiopathic pulmonary artery hypertension, 15 with peripheral chronic thromboembolic pulmonary hypertension, and 4 with portopulmonary hypertension Child-Pugh class A were included. Our control subjects were 56 blood donors. Total prolactin was measured with an immunoluminometric assay. Antibodies against epitope C detected only the intact prolactin before it was split. The 16-kDa PRL was calculated from the difference between total and intact prolactin.Prolactin was significantly (P=0.009) higher in the study group (median, 190 mU/L; interquartile range, 162 mU/L) than in the control group (median, 140 mU/L; interquartile range, 91 mU/L). The 16-kDa PRL was significantly elevated in the study group (P=0.046). Prolactin and 16-kDa PRL correlated inversely with the 6-minute-walk distance (P <0.01) and with peak oxygen uptake during exercise (P <0.005).Serum levels of prolactin and 16-kDa PRL were significantly higher in patients with precapillary pulmonary hypertension and were inversely correlated with 6-minute-walk distance and peak oxygen uptake.These results indicate that prolactin and 16-kDa PRL might play a role in the pathophysiology of precapillary pulmonary hypertension.