Sex disparities in popliteal artery aneurysms.

OBJECTIVE: Only 5% of patients with popliteal artery aneurysms (PAAs) are female. Evidence on PAA treatment and outcomes in women is therefore scarce. The POPART Registry provides one of Europe's largest data collections regarding PAA treatment. Data on clinical presentation, aneurysm morphology, and perioperative outcomes after open surgical PAA repair in women will be presented. METHODS: POPART is a multicenter, noninterventional registry for open and endovascular PAA repair, with 42 participating centers in Germany and Luxembourg. All patients aged >18 years who have been treated for PAA since 2010 are eligible for study inclusion. Data collection is based on an online electronic case report form. RESULTS: Of the 1236 PAAs, 58 (4.8%) were in women. There were no significant differences in age or cardiopulmonary comorbidities. However, female patients had a lower prevalence of contralateral PAAs and abdominal aortic aneurysms (P < .05). PAAs in women were more likely to be symptomatic before surgery (65.5% vs 49.4%; P = .017), with 19% of women presenting with acute limb ischemia (vs 11%; P = .067). Women had smaller aneurysm diameters than men (22.5 mm vs 27 mm; P = .004) and became symptomatic at smaller diameters (20 mm vs 26 mm; P = .002). Only 8.6% of women and 11.6% of men underwent endovascular aneurysm repair (P > .05); therefore, the perioperative outcome analysis focused on open surgical repair. In total, 23.5% of women and 16.9% of men developed perioperative complications (P > .05). There were no differences in major cardiovascular events (P > .05), but women showed a higher incidence of impaired wound healing (15.7% vs 7.2%; P = .05) and major amputation (5.9% vs 1.1%; P = .027). Female sex was significantly associated with the need for nonvascular reinterventions within 30 days after surgery (odds ratio: 2.48, 95% confidence interval: 1.26-4.88), whereas no significant differences in the odds for vascular reinterventions were observed (odds ratio: 1.98, 95% confidence interval: 0.68-5.77). In the multiple logistic regression model, female sex, symptomatic PAAs, poor quality of outflow vessels, and graft material other than vein graft were independently associated with perioperative reinterventions. CONCLUSIONS: Women have smaller PAAs, are more likely to be symptomatic before treatment, and are more often affected by nonvascular reinterventions in the perioperative course. As our understanding of aneurysmatic diseases in women continues to expand, sex-specific treatment strategies and screening options for women in well-selected cohorts with modified screening protocols should be continuously re-evaluated.

Isolated bacterial infection without decompensation has no impact on survival of compensated patients with cirrhosis.

BACKGROUND & AIMS: Bacterial infections (BI) affect the natural course of cirrhosis and were suggested to be a landmark event marking the transition to the decompensated stage. Our specific aim was to evaluate the impact of BI on the natural history of compensated cirrhosis. METHODS: We analyzed 858 patients with cirrhosis, evaluated for the INCA trial (EudraCT 2013-001626-26) in 2 academic medical centers between February 2014 and May 2019. Only patients with previously compensated disease were included. They were divided into 4 groups: compensated without BI, compensated with BI, 1st decompensation without BI, and 1st decompensation with BI. RESULTS: About 425 patients (median 61 [53-69] years) were included in the final prospective analysis. At baseline, 257 patients were compensated (12 [4.7%] with BI), whereas 168 patients presented with their 1st decompensation (42 [25.0%] with BI). In patients who remained compensated MELD scores were similar in those with and without BI. Patients with their first decompensation and BI had higher MELD scores than those without BI. Amongst patients who remained compensated, BI had no influence on transplant-free survival, whereas patients with their 1st decompensation and concurrent BI had significantly reduced transplant-free survival as compared with those without BI. The development of BI or decompensation during follow-up had a greater impact on survival than each of these complications at baseline. CONCLUSIONS: In compensated patients with cirrhosis, the 1st decompensation associated to BI has worse survival than decompensation without BI. By contrast, BI without decompensation does not negatively impact survival of patients with compensated cirrhosis.

Impact of body mass index, smoking habit, alcohol consumption, physical activity and parity on disease course of women with triple-negative breast cancer.

OBJECTIVE: To evaluate the potential impact of body mass index (BMI), smoking habit, alcohol consumption, physical activity and parity on disease course of women with triple-negative breast cancer (TNBC). MATERIAL AND METHODS: This was a retrospective chart analysis of patients with TNBC. Primary target parameters were overall survival (OS) and disease-free survival (DFS) depending on BMI, smoking habit, alcohol consumption, physical activity and parity. Results were descriptively evaluated and plotted as Kaplan-Meier curves. The null hypothesis was tested using the non-parametric log-rank test. All patients were treated at the University Medical School of Saarland, Dept of Gynecology, Obstetrics and Reproductive Medicine. RESULTS: A total of 197 patients were analyzed. More than 50% of women were 40-60 years old (mean 57 years) and had a normal BMI. More than 88% of patients had either a T1 or T2 tumor, 64% were N0 and 66.5% had a G3 cancer. Thirty-four of 84 patients (40.38%) on neo-adjuvant chemotherapy reached a pathology-confirmed complete remission. During the follow-up (median 41.43 months), 34 (17.3%) patients had recurrent disease and 51 (25.9%) suffered from metastases. A total of 51 (25.9%) finally deceased. OS and DFS were not significantly impacted by BMI (OS: p = 0.4720; DFS: p = 0.2272), smoking habit (p = 0.9892; p = 0.6040), alcohol consumption (p = 0.6515; p = 0.7460), physical activity (p = 0.3320; p = 0.5991) or parity (p = 0.5929; 0.1417). CONCLUSION: BMI, smoking habit, alcohol consumption, physical activity and parity had no impact on OS or DFS in women with TNBC.

Efficacy of low-temperature plasma-activated gas disinfection against biofilm on contaminated GI endoscope channels.

BACKGROUND AND AIMS: It has been increasingly recognized that the safety of GI endoscopes needs to be improved by addressing the small margin of safety of high-level disinfectants (HLDs) and the failure of HLDs to clear multidrug-resistant organisms and biofilms. There is also an unmet need for effective low-temperature sterilization techniques that have a clear pathway for U.S. Food and Drug Administration clearance. Here, we report the results of our investigation of a novel argon plasma-activated gas (PAG) for disinfection and potentially sterilization of biofilm-contaminated endoscopic channels. METHODS: Test polytetrafluoroethylene channel segments were contaminated with 4-, 24- and 48-hour luminal biofilms of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, or Escherichia coli and were treated by PAG flowing for up to 9 minutes. After PAG treatment, inactivation and dispersal of luminal bacterial biofilms and their regrowth in 48 hours were evaluated. Reactive species induced by PAG were measured with colorimetric probes and electron spin resonance spectrometry. Surface morphology and elemental composition of PAG-treated channel material were analyzed with scanning electron microscopy. RESULTS: PAG treatment for 9 minutes led to more than 8 log reduction of viable cells and dispersal of 24- and 48-hour luminal biofilms of all 3 bacteria and to suppression of their regrowth, whereas it resulted in little morphologic abnormalities in channel material. Ozone concentration of PAG fell to below .01 ppm within 30 seconds of switching off the plasma. PAG-treated deionized water was acidified with numerous types of reactive species, each with a concentration some 3 orders of magnitude or more below its bacterial inhibition concentration. CONCLUSIONS: PAG is capable of effectively and rapidly disinfecting luminal bacterial biofilms and offers an alternative to the step of HLDs and/or ethylene oxide in the endoscope reprocessing procedure with safety to personnel and environment.

Noncanonical RNA Nucleosides as Molecular Fossils of an Early Earth-Generation by Prebiotic Methylations and Carbamoylations.

The RNA-world hypothesis assumes that life on Earth started with small RNA molecules that catalyzed their own formation. Vital to this hypothesis is the need for prebiotic routes towards RNA. Contemporary RNA, however, is not only constructed from the four canonical nucleobases (A, C, G, and U), it also contains many chemically modified (noncanonical) bases. A still open question is whether these noncanonical bases were formed in parallel to the canonical bases (chemical origin) or later, when life demanded higher functional diversity (biological origin). Here we show that isocyanates in combination with sodium nitrite establish methylating and carbamoylating reactivity compatible with early Earth conditions. These reactions lead to the formation of methylated and amino acid modified nucleosides that are still extant. Our data provide a plausible scenario for the chemical origin of certain noncanonical bases, which suggests that they are fossils of an early Earth.

Octadentate Picolinic Acid-Based Bispidine Ligand for Radiometal Ions.

The synthesis of the octadentate bispidine ligand bearing two picolinic acid pendant arms (H2 bispa2 ), and its coordination chemistry with radionuclides relevant for nuclear medicine, namely indium(III) (111 In), lutetium(III) (177 Lu), and lanthanum(III) (as surrogate for 225 Ac), are reported. The non-radioactive metal complexes of the N6 O2 -type bispa ligand were characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, mass spectrometry and single-crystal X-ray analysis. Experimental structural data, computational analysis, complex stabilities determined by potentiometric titration, and "radiostabilities" determined by competition studies in the presence of human serum reveal complex stabilities of H2 bispa2 comparable to those of the macrocyclic "gold standard" DOTA. After an incubation time of 1 day, 86 and 87 % of [177 Lu(bispa2 )]+ and [177 Lu(DOTA)]- , respectively, remain intact. Importantly, unlike DOTA, H2 bispa2 is radiolabeled quantitatively with 111 InIII and 225 AcIII under ambient conditions, which is an essential aspect when working with heat-sensitive antibodies as targeting vectors. In the case of 111 InIII , room temperature radiolabeling of H2 bispa2 yields molar activities as high as 70 MBq nmol-1 within 10 minutes. These are promising results for radiopharmaceutical applications of H2 bispa2 .

Stable Isotope-Assisted Evaluation of Different Extraction Solvents for Untargeted Metabolomics of Plants.

The evaluation of extraction protocols for untargeted metabolomics approaches is still difficult. We have applied a novel stable isotope-assisted workflow for untargeted LC-HRMS-based plant metabolomics , which allows for the first time every detected feature to be considered for method evaluation. The efficiency and complementarity of commonly used extraction solvents, namely 1 + 3 (v/v) mixtures of water and selected organic solvents (methanol, acetonitrile or methanol/acetonitrile 1 + 1 (v/v)), with and without the addition of 0.1% (v/v) formic acid were compared. Four different wheat organs were sampled, extracted and analysed by LC-HRMS. Data evaluation was performed with the in-house-developed MetExtract II software and R. With all tested solvents a total of 871 metabolites were extracted in ear, 785 in stem, 733 in leaf and 517 in root samples, respectively. Between 48% (stem) and 57% (ear) of the metabolites detected in a particular organ were found with all extraction mixtures, and 127 of 996 metabolites were consistently shared between all extraction agent/organ combinations. In aqueous methanol, acidification with formic acid led to pronounced pH dependency regarding the precision of metabolite abundance and the number of detectable metabolites, whereas extracts of acetonitrile-containing mixtures were less affected. Moreover, methanol and acetonitrile have been found to be complementary with respect to extraction efficiency. Interestingly, the beneficial properties of both solvents can be combined by the use of a water-methanol-acetonitrile mixture for global metabolite extraction instead of aqueous methanol or aqueous acetonitrile alone.

A case of paroxysmal nocturnal hemoglobinuria caused by a germline mutation and a somatic mutation in PIGT.

To ascertain the genetic basis of a paroxysmal nocturnal hemoglobinuria (PNH) case without somatic mutations in PIGA, we performed deep next-generation sequencing on all exons of known genes of the glycosylphosphatidylinositol (GPI) anchor synthesis pathway. We identified a heterozygous germline splice site mutation in PIGT and a somatic 8-MB deletion in granulocytes affecting the other copy of PIGT. PIGA is essential for GPI anchor synthesis, whereas PIGT is essential for attachment of the preassembled GPI anchor to proteins. Although a single mutation event in the X-chromosomal gene PIGA is known to cause GPI-anchored protein deficiency, 2 such hits are required in the autosomal gene PIGT. Our data indicate that PNH can occur even in the presence of fully assembled GPI if its transfer to proteins is defective in hematopoietic stem cells.

Retrospective study of the incidence, risk factors, treatment outcomes of bacterial infections at uncommon sites in cirrhotic patients.

BACKGROUND: Bacterial infections (BI) negatively affect the natural course of cirrhosis. The most frequent BI are urinary tract infections (UTI), pneumonia, and spontaneous-bacterial peritonitis (SBP). AIM: To assess the relevance of bacterial infections beyond the commonly recognized types in patients with cirrhosis and to investigate their relationship with other clinical variables. METHODS: We retrospectively analyzed patients with cirrhosis and BI treated between 2015 and 2018 at our tertiary care center. BIs were classified as typical and atypical, and clinical as well as laboratory parameters were compared between the two groups. RESULTS: In a cohort of 488 patients with cirrhosis, we identified 225 typical BI (95 UTI, 73 SBP, 72 pulmonary infections) and 74 atypical BIs, predominantly cholangitis and soft tissue infections (21 each), followed by intra-abdominal BIs (n = 9), cholecystitis (n = 6), head/throat BIs (n = 6), osteoarticular BIs (n = 5), and endocarditis (n = 3). We did not observe differences concerning age, sex, or etiology of cirrhosis in patients with typical vs atypical BI. Atypical BIs were more common in patients with more advanced cirrhosis, as evidenced by Model of End Stage Liver Disease (15.1 ± 7.4 vs 12.9 ± 5.1; P = 0.005) and Child-Pugh scores (8.6 ± 2.5 vs 8.0 ± 2; P = 0.05). CONCLUSION: Atypical BIs in cirrhosis patients exhibit a distinct spectrum and are associated with more advanced stages of the disease. Hence, the work-up of cirrhosis patients with suspected BI requires detailed work-up to elucidate whether typical BI can be identified.

A Novel Xanthomonas sp. Causes Bacterial Spot of Rose (Rosa spp.).

A bacterial spot of rose (Rosa spp.) caused by a xanthomonad was observed in Florida and Texas. Ten representative strains collected from the two states between 2004 and 2010 were used to determine the taxonomic position of this rose pathogen. Fatty acid methyl ester analysis was performed and a nearly 2-kb 16S-23S rRNA intergenic spacer along with flanking portions of the 16S and 23S rRNA genes were sequenced for selected strains, showing that they were members of the genus Xanthomonas. Multilocus sequence typing and analysis (MLST/MLSA) and pathogenicity tests were conducted to further characterize the Xanthomonas strains. The MLSA, based on six gene fragments-fusA, gapA, gltA, gyrB, lacF, and lepA-showed that the rose strains fell into Xanthomonas axonopodis subgroup 9.2 and shared the highest similarity values (98.8 to 99.7%) with X. alfalfae subsp. citrumelonis of the subgroup. However, principal coordinate analysis grouped the rose strains into a unique cluster distinct from other members of the subgroup according to virulence phenotypes on 11 plant species belonging to five plant families (Araceae, Euphorbiaceae, Rosaceae, Rutaceae, and Solanaceae). Moreover, the rose strains were aggressive on rose and Indian Hawthorn (Rhaphiolepsis indica). On the basis of the MLSA and virulence phenotypes, the pathovar epithet rosa is proposed.

Development of hypothyroidism during long-term follow-up of patients with toxic nodular goitre after radioiodine therapy.

OBJECTIVE: To investigate the cure rate and incidence of hypothyroidism of radioiodine treatment with a calculated dose regimen and an intended thyroid dose of 150 Gy in patients with toxic nodular goitre during long-term follow-up. PATIENTS: A total of 265 consecutive patients with toxic nodular goitre were treated between March 2003 and August 2004 at our institute and followed up for a maximum of 8 years. Preliminary radioiodine testing with volumetric measurement of the thyroid by ultrasound as well as individual thyroidal radioiodine uptake and half-life measurements were performed before radioiodine therapy. The estimated radiation dose to the thyroid was 150 Gy. MEASUREMENTS: Follow-up controls with respect to success of therapy and development of hypothyroidism were performed 3 months, 1 and up to 8 years after radioiodine treatment. The relation of the achieved thyroid dose to the success rate of treatment and to the incidence of hypothyroidism was analysed. RESULTS: The cure rates were 85% at 3 months, 98% at 1 year and 98% at the end of follow-up. Above an achieved thyroid dose of more than 120 Gy, there was no significant association between the dose achieved in the thyroid and the cure rate on follow-up. The incidences of hypothyroidism at 3 months, at 1 year and at the end of follow-up were 32%, 55% and 73%, respectively. CONCLUSIONS: Radioiodine treatment with a calculated dose regimen is a highly effective treatment option in patients with toxic goitre with an overall success rate of 98%. However, radioiodine treatment with an intended thyroid dose of 150 Gy leads to a high incidence of hypothyroidism on long-term follow-up. This finding supports the suggestion that in future intended thyroid doses could be lowered in patients treated with a calculated dose regimen for toxic nodular goitre.

maat: An R Package for Multiple Administrations Adaptive Testing.

Multiple Administrations Adaptive Testing (MAAT) is an extension of the shadow-test approach to CAT for the assessment framework involving multiple tests administered periodically throughout the year. The maat package utilizes multiple item pools vertically scaled across grades and multiple phases (stages) within each test administration, allowing for transitioning from an item pool to another as deemed necessary to further enhance the quality of assessment.

Protective Effects of Statin Therapy in Cirrhosis Are Limited by a Common SLCO1B1 Transporter Variant.

Complications of cirrhosis and portal hypertension (PH) can be reduced by statin therapy. The common loss-of-function variant p.V174A in the solute carrier organic anion transporter gene 1B1 (SLCO1B1) gene encoding the organic anion transporting polypeptide 1B1 results in decreased hepatic uptake of statins. Our specific aim was to assess the impact of this variant in patients with cirrhosis and statin treatment while controlling for the stage of cirrhosis and other potential confounders with propensity score matching (PSM), availing of a large cohort of genotyped study patients. In total, from 1,088 patients with cirrhosis in two German academic medical centers, PSM yielded 154 patients taking statins and 154 matched controls. The effect on PH was assessed by the liver stiffness-spleen size-to-platelet score (LSPS), and complications of cirrhosis were retrospectively recorded applying consensus criteria. As hypothesized, patients on statin treatment presented less frequently with signs of PH: Esophageal varices (41% vs. 62%; P < 0.001) were less common, and LSPS (4.8 ± 11.5 vs. 5.6 ± 6.4; P = 0.01) was reduced. Correspondingly, decompensation events were also reduced in patients on statins (odds ratio [OR] = 0.54, 95% confidence interval [CI] 0.32-0.90; P = 0.02). When the variant in SLCO1B1 was present in patients on statins, esophageal varices (OR = 2.68, 95% CI 1.24-5.81; P = 0.01) and bacterial infections (OR = 2.50, 95% CI 1.14-5.47; P = 0.02) were more common as compared with wild type carriers on statins. Conclusion: In this cohort, signs and complications of PH were reduced in patients with cirrhosis treated with statins. Notably, this effect was diminished by the common loss-of-function variant in SLCO1B1. Further prospective studies in independent cohorts are warranted to confirm these genotype-specific observations.

Late-gestational systemic hypoxia leads to a similar early gene response in mouse placenta and developing brain.

Late-gestational intrauterine hypoxia represents a well-known risk factor of acquired perinatal brain injury. Cell type and age-specific sensitivity of hypoxia-responsive genes to low-oxygen partial pressure is to be considered in the screening for early indicators of fetoplacental tissue hypoxia. To identify early hypoxia-induced alterations in gene expression during late-gestational hypoxia (6% O(2), 6 h; gestational day 20) we compared primary mouse placenta and brain transcriptomes using high-density oligonucleotide microarrays. Upregulation of candidate marker genes for hypoxia was confirmed by quantitative RT-PCR and immunohistochemistry. Both developing brain and placenta were highly responsive to systemic hypoxia at the level of gene expression involving hypoxia-inducible transcription factor (HIF)-dependent genes and immediate early genes (IEG) (Fos, Jun, Egr1, Bhlhb2), apoptosis-promoting factors (Bnip3, Dusp1, Ier3) that were all upregulated, and genes modulating RNA binding and translation (Rbm3, Thap2, Lig4, Rbm12b) that mainly were downregulated. Functional activity of the HIF system was obvious from elevated expression of various known HIF target genes (Adm, Vegf, Hk2, Pdk1, Bnip3, Ier3, Dusp-1), indicating immediate availability among early response to acute hypoxia. In addition, genes not yet described as being hypoxia related were identified that are involved in angiogenesis/cell differentiation (Gna13, Gab2), mRNA processing, and embryonic development. RT-PCR of placenta and brain tissues confirmed upregulation of selected HIF target genes and IEG. These data indicate that the early hypoxia-induced genomic response of the placenta mirrors that of developing brain in a temporally parallel manner. Our observations implicate future diagnostic options to identify fetal and cerebral tissue hypoxia.

Thyroid hemiagenesis is combined with a variety of thyroid disorders.

AIM: Thyroid hemiagenesis (TH) is a rare congenital anomaly in which one thyroid lobe fails to develop. We describe our experience with at least 13 patients presenting with TH at our department. METHODS: We retrospectively analysed patients with TH, who had been referred primarily to our clinic between 2004 and 2010. In patients with TH, thyroid function parameters and thyroid autoantibodies were examined. 99mTc-pertechnetate thyroid scintigraphy and sonography were performed in all patients and confirmed the diagnosis of TH. RESULTS: We identified 13 patients (11 women, 2 men) with TH in our patient collective and calculated an estimated prevalence of TH of 0.08 %.We found TH to occur more frequently in the left lobe and also more frequently in females than in males. 9 patients presented with a total absence of one thyroid lobe and 4 patients presented with severe hypoplasia of one thyroid lobe with an isthmus appearing as a "hockey stick sign" on scintigraphic imaging. Associated thyroid diseases could be observed in the remaining lobe in all patients and included hyperthyroidism, hypothyroidism, nodular goiter, toxic goiter, hypofunctioning nodules, Graves' disease and Hashimoto-thyroiditis. The most frequent thyroid disease in our patients with TH was nodular goiter. We did not find any association of TH with malignancy. CONCLUSION: TH is mostly detected incidentally as the prevalence of TH is extraordinary low. The fact that all of our patients with TH were also affected by other forms of thyroid disease is reasonable since the patients were not referred to the diagnostic centre due to TH but rather due to the associated thyroid disease. Possibly there are different groups of TH: the symptomatic hypothyroid children, the lifelong euthyroid adults who are diagnosed incidentally through another thyroid disease and the patients with a molecular failure of proper thyroid development.

Publisher Correction: Non-canonical nucleosides and chemistry of the emergence of life.

The original version of this Article contained errors in the citations in the second, third and fourth sentences of the first paragraph of the 'Life and LUCA' section, which incorrectly read 'Its development is explained by Darwinian evolution, which must have begun with rudimentary "living" vesicles that at some point transitioned into what we call the last universal common ancestor (LUCA)2. LUCA is a hypothetical life form obtained from phylogenetic analysis from which all three kingdoms of life originated3. To our understanding, LUCA already possessed the capacity to synthesize specific building blocks such as amino acids, nucleotides and lipids2.' The correct version states '(LUCA)1' in place of '(LUCA)2', 'originated2' instead of 'originated3' and 'lipids1' rather than 'lipids2'. This has been corrected in both the PDF and HTML versions of the Article.

Unified prebiotically plausible synthesis of pyrimidine and purine RNA ribonucleotides.

Theories about the origin of life require chemical pathways that allow formation of life's key building blocks under prebiotically plausible conditions. Complex molecules like RNA must have originated from small molecules whose reactivity was guided by physico-chemical processes. RNA is constructed from purine and pyrimidine nucleosides, both of which are required for accurate information transfer, and thus Darwinian evolution. Separate pathways to purines and pyrimidines have been reported, but their concurrent syntheses remain a challenge. We report the synthesis of the pyrimidine nucleosides from small molecules and ribose, driven solely by wet-dry cycles. In the presence of phosphate-containing minerals, 5'-mono- and diphosphates also form selectively in one-pot reactions. The pathway is compatible with purine synthesis, allowing the concurrent formation of all Watson-Crick bases.

Non-canonical nucleosides and chemistry of the emergence of life.

Prebiotic chemistry, driven by changing environmental parameters provides canonical and a multitude of non-canonical nucleosides. This suggests that Watson-Crick base pairs were selected from a diverse pool of nucleosides in a pre-Darwinian chemical evolution process.

Wet-dry cycles enable the parallel origin of canonical and non-canonical nucleosides by continuous synthesis.

The molecules of life were created by a continuous physicochemical process on an early Earth. In this hadean environment, chemical transformations were driven by fluctuations of the naturally given physical parameters established for example by wet-dry cycles. These conditions might have allowed for the formation of (self)-replicating RNA as the fundamental biopolymer during chemical evolution. The question of how a complex multistep chemical synthesis of RNA building blocks was possible in such an environment remains unanswered. Here we report that geothermal fields could provide the right setup for establishing wet-dry cycles that allow for the synthesis of RNA nucleosides by continuous synthesis. Our model provides both the canonical and many ubiquitous non-canonical purine nucleosides in parallel by simple changes of physical parameters such as temperature, pH and concentration. The data show that modified nucleosides were potentially formed as competitor molecules. They could in this sense be considered as molecular fossils.