Prebiotic synthesis of cysteine peptides that catalyze peptide ligation in neutral water

Peptide biosynthesis is performed by ribosomes and several other classes of enzymes, but a simple chemical synthesis may have created the first peptides at the origins of life. α-Aminonitriles-prebiotic α-amino acid precursors-are generally produced by Strecker reactions. However, cysteine's aminothiol is incompatible with nitriles. Consequently, cysteine nitrile is not stable, and cysteine has been proposed to be a product of evolution, not prebiotic chemistry. We now report a high-yielding, prebiotic synthesis of cysteine peptides. Our biomimetic pathway converts serine to cysteine by nitrile-activated dehydroalanine synthesis. We also demonstrate that N-acylcysteines catalyze peptide ligation, directly coupling kinetically stable-but energy-rich-α-amidonitriles to proteinogenic amines. This rare example of selective and efficient organocatalysis in water implicates cysteine as both catalyst and precursor in prebiotic peptide synthesis.

A Chemist's Perspective on the Role of Phosphorus at the Origins of Life

The central role that phosphates play in biological systems, suggests they also played an important role in the emergence of life on Earth. In recent years, numerous important advances have been made towards understanding the influence that phosphates may have had on prebiotic chemistry, and here, we highlight two important aspects of prebiotic phosphate chemistry. Firstly, we discuss prebiotic phosphorylation reactions; we specifically contrast aqueous electrophilic phosphorylation, and aqueous nucleophilic phosphorylation strategies, with dry-state phosphorylations that are mediated by dissociative phosphoryl-transfer. Secondly, we discuss the non-structural roles that phosphates can play in prebiotic chemistry. Here, we focus on the mechanisms by which phosphate has guided prebiotic reactivity through catalysis or buffering effects, to facilitating selective transformations in neutral water. Several prebiotic routes towards the synthesis of nucleotides, amino acids, and core metabolites, that have been facilitated or controlled by phosphate acting as a general acid-base catalyst, pH buffer, or a chemical buffer, are outlined. These facile and subtle mechanisms for incorporation and exploitation of phosphates to orchestrate selective, robust prebiotic chemistry, coupled with the central and universally conserved roles of phosphates in biochemistry, provide an increasingly clear message that understanding phosphate chemistry will be a key element in elucidating the origins of life on Earth.

Selective aqueous acetylation controls the photoanomerization of α-cytidine-5'-phosphate

Nucleic acids are central to information transfer and replication in living systems, providing the molecular foundations of Darwinian evolution. Here we report that prebiotic acetylation of the non-natural, but prebiotically plausible, ribonucleotide α-cytidine-5'-phosphate, selectively protects the vicinal diol moiety. Vicinal diol acetylation blocks oxazolidinone formation and prevents C2'-epimerization upon irradiation with UV-light. Consequently, acetylation enhances (4-fold) the photoanomerization of α-cytidine-5'-phosphate to produce the natural β-pyrimidine ribonucleotide-5'-phosphates required for RNA synthesis.

Prebiotic synthesis of aminooxazoline-5'-phosphates in water by oxidative phosphorylation

RNA is essential to all life on Earth and is the leading candidate for the first biopolymer of life. Aminooxazolines have recently emerged as key prebiotic ribonucleotide precursors, and here we develop a novel strategy for aminooxazoline-5'-phosphate synthesis in water from prebiotic feedstocks. Oxidation of acrolein delivers glycidaldehyde (90%), which directs a regioselective phosphorylation in water and specifically affords 5'-phosphorylated nucleotide precursors in upto 36% yield. We also demonstrated a generational link between proteinogenic amino acids (Met, Glu, Gln) and nucleotide synthesis.

Solid phase synthesis of N-carboxy alkyl-containing peptides derived from enantiopure alpha-keto-beta-aminoacids

alpha-Keto-beta-aminoacids 5a-c can be reductively aminated with the peptide sequence H2N-Leu-Val-Phe-Phe on a solid support to afford N-carboxy alkyl peptides 1a-c. The N-carboxy alkyl lysine derivative 7 was subsequently extended from the N-terminus with glutamine and histidine residues.

[Randomised clinical trial to compare two tracheotomy care methods in an Intensive Care Unit]

INTRODUCTION

Tracheotomy is a common technique in Intensive Care Units (ICU). It is known that nursing care during and after that procedure is directly related to its success, by reducing the possible complications to a minimum, such as the stoma infection, and contributing to a favourable outcome in critical patients.

OBJECTIVES

To compare the use of polyhexanide (PLX) versus saline+povidone iodine (PY) as antiseptics and infection incidence in tracheostomies performed in Intensive Care Units.

MATERIAL AND METHOD

A 2-year, experimental, randomised, open-label trial carried out in a multidiscipline ICU with 32 beds. The study was approved by the Research Ethics Committee of Principality of Asturias.

RESULTS

The overall infection rate observed for every hundred patients was 1.34 (95% CI; 0.81-2.01), with 1.46 when using PLX and 1.21 for PY (P=.685).

CONCLUSIONS

In spite of the experimental treatment (PLX) was shown to be effective in other types of wounds in our study. No significant differences were found between this technique and the standard one. Since there is no national registry of tracheotomy- associated infections, it is not possible to know whether the rate observed is within the usual parameters.

[Predictive mortality factors and the development of major complications in non-traumatic subarachnoid hemorrhage]

Our aim was to analyze death prognostic factors in the first six months or the development of major neurological complications (delayed brain ischaemia and rebleeding) or general complications (cardiorespiratory, hydroelectrolytic or infectious) in non-traumatic subarachnoid haemorrhage. We carried out an observational study of a historical cohort of 111 patients admitted consecutively to our Centre between 1986 and 1992 and who were diagnosed as having subarachnoid haemorrhage based upon clinical data and confirmed in all cases by brain computerized tomography (CT) scan and/or lumbar puncture. Clinical variables upon admission were collected prospectively and radiological data were obtained retrospectively. We performed a logistic regression analysis which showed as significant predictive variables for death in the first six months a score on the Hunt-Hess scale greater than 2, a score on the Glassow scale of less than 9, female, aged over 50 and rebleeding. As predictive factors for delayed brain ischaemia we identified the female sex and the existence of earlier general complications. In the development of rebleeding a significant predictive factor was high blood pressure antecedents although this may have been controlled upon admission. For the appearance of general complications, significant predictive factors were more than 2 on the Hunt-Hess scale and hypertension antecedents. The use of these predictive parameters may help evaluate a prognosis in subarachnoid haemorrhage patients and also help make decisions in the management of this pathology.

Ivabradine in treatment of symptomatic heart failure and supraventricular tachycardias in patients under six months of age

Background

Although heart failure (HF) and supraventricular tachycardias (SVT) are associated with high morbidity and mortality in pediatrics, especially, in children under 6 months; the efficacy of available treatments is limited, requiring the use of off-label therapies. The aim of the study is to investigate the efficacy, dosage, and safety of off-label ivabradine in patients under 6 months of age with HF or SVT.

Methods

Retrospective observational study, which included patients under 6 months of age with HF or SVT who received ivabradine between January 2020 - May 2024. Demographic, clinical, and treatment-related variables were collected. Response variables were established according to indication, HF: heart rate (HR) and left ventricular ejection fraction (LVEF); SVT: HR.

Results

Thirteen patients (nine women) with a median age of 1.4 (1-4) months were included. Ivabradine was discontinued in five of the seven HF patients due to resolution of HF, control of HR, and improvement of LVEF. One patient discontinued ivabradine because of bradycardia. In the SVT group, four of the seven patients discontinued ivabradine after the resolution of tachyarrhythmia and improvement of HR. Two patients experienced bradycardia but did not require treatment discontinuation. HR reduction was statistically significant in both groups. In HF, the median initial ivabradine dose was 0.06 mg/kg/day and the maintenance dose was 0.2 mg/kg/day. In SVT, the initial and maintenance doses were 0.1 mg/kg/day and 0.24 mg/kg/day, respectively.

Conclusion

Ivabradine demonstrated favorable efficacy and safety results in patients under 6 months of age with HF or SVT.

[Stereotactic target identification for neurosurgery of Parkinson disease]

INTRODUCTION

The use of applied neurophysiological methods to improve the stereotactic localization of devices in the deep human brain is a high and systematic technology in Parkinson's neurosurgery today. The available standard equipment for clinical neurophysiology practice may constitute the basic set for high tech functional neurosurgery. Free run and event related multiunit recording, naturalistic and electrical evoked potentials, and deep brain microstimulation responses are the basic methodological set to neurophysiological target localization.

DEVELOPMENT AND CONCLUSIONS

This article is concerned with the topic: set out a high technology using low cost equipment. So our 41 cases experienced in pallidal and thalamic nucleolisis and thalamus and subthalamus DBS results suggest that the proposed equipment and methods are the required to assure accuracy and safety for target location.

[What sort of stroke requires patient admittance to the hospital? Factors for deciding on hospitalization]

OBJECTIVE

To study main factors determining medical decision in admitting patients with acute cerebrovascular disease (ACVD).

PATIENTS AND METHODS

This is an observational and transversal study. We analyze a hospitalary cohort made by all consecutive patients with ACVD coming to Emergency Room to Hospital Universitario de la Princesa during 1 year. Neurologist on call made on his/her own decision to admit the patient to hospital. Clinical and epidemiological characteristics of those patients admitted with those who went home are compared.

RESULTS

517 patients were studied, 147 had transient ischemic attacks (TIA) and 370 had a stroke, 12.3% TIA and 68.4% stroke patients were hospitalized. Age, Canadian Stroke Scale (CSS) on admission, subtype of stroke, atrial fibrillation and abnormal EKG, old lesions in CT, previous TIA and/or CVD, diminished conscious level, orientation and language, sphincter control and evolution time greater than 48 hours were statistically significative in deciding admission. Logistic regression analysis (84.2% total predictive value) showed independent predictive value in age, CSS, previous CVD and some subtypes of stroke (ischemic non lacunar and hemorrhage).

CONCLUSIONS

We hospitalize younger patients, with a worse clinical condition and overall hemorrhagic stroke. The percentage of admissions among TIA patients is low. On the other hand, date, time and physicians-team features do not affect the percentage of admissions.