66 research outputs found
Djelovanje karboksilnih kiselina na crveno obojenje cvjetova žutinice
Eight carboxylic acids were fed at 1-10000 pM to the flower pastes from fresh dyer’s saffron (Carthamus tinctorius L.) capitula and their effects on the red colouration investigated. Glyoxyllic acid, glycolic acid, oxaloacetic acid, 2-oxoglutaric acid and gluconic acid were found to be positive stimulators for the reaction, while succinic acid, malic acid and citric acid inhibited the colour change.Svojim ranijim istraživanjima autori su pokazali da usitnjeni cvjetovi žutinice (Carthamus tinctorius L.) poprime crvenu boju ako na njih djeluju otopine aminokiselina. Učinkovitost pojedine aminokiseline ovisi o tipu: kisele amino- kiseline bile su najučinkovitije, neutralne nešto manje, one s aromatičnim skupinama ili skupinama sa sumporom još manje, dok su bazične aminokiseline bile najmanje učinkovite. Za objašnjenje ovih rezultata bilo je potrebno da se ustanove još drugi metaboliti koji biokatalitički utječu na promjenu boje cvjetova. U ovom prilogu autori objavljuju podatke o promjenama boje nakon primjene karboksilnih kiselina.
U tu svrhu istražili su djelovanje osam karboksilnih kiselina u koncentracijama od 1 - 10000 pM na kašu od zdrobljenih cvjetova žutinice (Carthamus tinctorius L.). Postignuti rezultati su pokazali da glioksilna, glikolna, oksalooc- tena, 2-oksoglutarna i glukonska kiselina pospješuju reakciju stvaranja crvenog bojila, dok jantarna, jabučna i limunska kiselina tu reakciju inhibiraju. U radu se navode točni podaci o materijalu, metodama rada i rezultatima koji su prikazani u preglednoj tabeli. Rezultate autori kratko komentiraju uz razmišljanja da bi kemijske strukture karboksilnih kiselina mogle biti uže povezane s procesima promjene bojila, iako je sam mehanizam reakcije zasad još nepoznat
Rh-POP Pincer Xantphos Complexes for C-S and C-H Activation. Implications for Carbothiolation Catalysis
The neutral Rh(I)–Xantphos
complex [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Cl]<sub><i>n</i></sub>, <b>4</b>, and cationic Rh(III) [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(H)<sub>2</sub>][BAr<sup>F</sup><sub>4</sub>], <b>2a</b>, and [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>)(H)<sub>2</sub>][BAr<sup>F</sup><sub>4</sub>], <b>2b</b>, are described [Ar<sup>F</sup> = 3,5-(CF<sub>3</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>; Xantphos
= 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub> = 9,9-dimethylxanthene-4,5-bis(bis(3,5-bis(trifluoromethyl)phenyl)phosphine].
A solid-state structure of <b>2b</b> isolated from C<sub>6</sub>H<sub>5</sub>Cl solution shows a κ<sup>1</sup>-chlorobenzene
adduct, [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>)(H)<sub>2</sub>(κ<sup>1</sup>-ClC<sub>6</sub>H<sub>5</sub>)][BAr<sup>F</sup><sub>4</sub>], <b>3</b>. Addition of H<sub>2</sub> to <b>4</b> affords,
crystallographically characterized, [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(H)<sub>2</sub>Cl], <b>5</b>. Addition of diphenyl
acetylene to <b>2a</b> results in the formation of the C–H
activated metallacyclopentadiene [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(ClCH<sub>2</sub>Cl)(σ,σ-(C<sub>6</sub>H<sub>4</sub>)C(H)CPh)][BAr<sup>F</sup><sub>4</sub>], <b>7</b>, a rare example of a crystallographically characterized Rh–dichloromethane
complex, alongside the Rh(I) complex <i>mer</i>-[Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(η<sup>2</sup>-PhCCPh)][BAr<sup>F</sup><sub>4</sub>], <b>6</b>. Halide abstraction from [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Cl]<sub><i>n</i></sub> in the presence of diphenylacetylene affords <b>6</b> as the
only product, which in the solid state shows that the alkyne binds
perpendicular to the κ<sup>3</sup>-POP Xantphos ligand plane.
This complex acts as a latent source of the [Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)]<sup>+</sup> fragment and facilitates
<i>ortho</i>-directed C–S activation in a number
of 2-arylsulfides to give <i>mer</i>-[Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(σ,κ<sup>1</sup>-Ar)(SMe)][BAr<sup>F</sup><sub>4</sub>] (Ar = C<sub>6</sub>H<sub>4</sub>COMe, <b>8</b>; C<sub>6</sub>H<sub>4</sub>(CO)OMe, <b>9</b>; C<sub>6</sub>H<sub>4</sub>NO<sub>2</sub>, <b>10</b>; C<sub>6</sub>H<sub>4</sub>CNCH<sub>2</sub>CH<sub>2</sub>O, <b>11</b>; C<sub>6</sub>H<sub>4</sub>C<sub>5</sub>H<sub>4</sub>N, <b>12</b>).
Similar C–S bond cleavage is observed with allyl sulfide,
to give <i>fac</i>-[Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(η<sup>3</sup>-C<sub>3</sub>H<sub>5</sub>)(SPh)][BAr<sup>F</sup><sub>4</sub>], <b>13</b>. These products of C–S
activation have been crystallographically characterized. For <b>8</b> in situ monitoring of the reaction by NMR spectroscopy reveals
the initial formation of <i>fac</i>-κ<sup>3</sup>-<b>8</b>, which then proceeds to isomerize to the <i>mer</i>-isomer. With the <i>para</i>-ketone aryl sulfide, 4-SMeC <sub>6</sub>H<sub>4</sub>COMe, C–H activation <i>ortho</i> to the ketone occurs to give <i>mer</i>-[Rh(κ<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)(σ,κ<sup>1</sup>-4-(COMe)C<sub>6</sub>H<sub>3</sub>SMe)(H)][BAr<sup>F</sup><sub>4</sub>], <b>14</b>. The temporal evolution of carbothiolation catalysis using <i>mer</i>-κ<sup>3</sup>-<b>8</b>, and phenyl acetylene
and 2-(methylthio)acetophenone substrates shows initial fast catalysis
and then a considerably slower evolution of the product. We suggest
that the initially formed <i>fac</i>-isomer of the C–S
activation product is considerably more active than the <i>mer</i>-isomer (i.e., <i>mer</i>-<b>8</b>), the latter of
which is formed rapidly by isomerization, and this accounts for the
observed difference in rates. A likely mechanism is proposed based
upon these data
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20
[1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030
Carbon-carbon bond construction using boronic acids and aryl methyl sulfides: orthogonal reactivity in Suzuki-type couplings
The Rh(i)-catalysed coupling of aryl and alkenyl boronic acids with simple aryl and alkenyl methyl sulfides is reported. The process employs bench-stable Rh(i) precatalysts incorporating small bite-angle chelating phosphine ligands (R2PCH2PR2, R = iPr, Cy), shows good functional group tolerance, and proceeds under mild reaction conditions. Importantly, aryl bromide activating groups are inert to the reaction conditions, allowing selective reaction at either a methyl sulfide or bromide activating group, depending on catalyst (metal) choice. The scope of the coupling reactions, their combination with Rh-catalysed hydroacylation reactions in cascade processes, together with preliminary mechanistic studies, are all documented. This journal is © The Royal Society of Chemistry 2013
Relative binding affinities of fluorobenzene ligands in cationic rhodium bisphosphine η 6-fluorobenzene complexes probed using collision-induced dissociation
A range of cationic rhodium bisphosphine η 6-fluorobenzene (fluorobenzenes = C6H6-n F n , n = 1-3) and related complexes have been synthesized and characterized. These complexes act as useful organometallic precursors for catalysis or further synthetic elaboration. The relative binding affinity of the arene ligands has been investigated using Electrospray Ionisation Mass Spectrometry (ESI-MS) and two different collision-induced dissociation (CID) techniques. The influence of arene fluorination upon arene binding affinity is discussed as well as the comparison of different bis-phosphine ligands with regard to bite angle and phosphine substitution. We show that this simple technique allows fast and easy comparison of the binding affinity of arene ligands to cationic organometallic fragments
Patient-Derived Cancer Organoids for Precision Oncology Treatment
The emergence of three-dimensional human organoids has opened the door for the development of patient-derived cancer organoid (PDO) models, which closely recapitulate parental tumor tissue. The mainstays of preclinical cancer modeling include in vitro cell lines and patient-derived xenografts, but these models lack the cellular heterogeneity seen in human tumors. Moreover, xenograft establishment is resource and time intensive, rendering these models difficult to use to inform clinical trials and decisions. PDOs, however, can be created efficiently and retain tumor-specific properties such as cellular heterogeneity, cell–cell and cell–stroma interactions, the tumor microenvironment, and therapeutic responsiveness. PDO models and drug-screening protocols have been described for several solid tumors and, more recently, for gliomas. Since PDOs can be developed in clinically relevant time frames and share many characteristics of parent tumors, they may enhance the ability to provide precision oncologic care for patients. This review explores the current literature on cancer organoids, highlighting the history of PDO development, organoid models of glioma, and potential clinical applications of PDOs
Simultaneous Functionalization of Carbon Surfaces with Rhodium and Iridium Organometallic Complexes: Hybrid Bimetallic Catalysts for Hydroamination
Carbon-based surfaces were explored here for the synthesis of heterometallic surface-bound catalysts. This takes advantage of catalytic enhancements found using bimetallic catalysts relative to monometallic analogues, as well as the advantages of heterogeneous catalysts over homogeneous catalysts. To achieve this, two organometallic cations with different metal centers, oxidation states, and coligands, [Rh(N,N′)(CO) 2 ] + and [Ir(N,N′)Cp∗Cl] + (N,N′ = pyrazolyltriazolylmethane ligands), were simultaneously immobilized onto the surface of carbon materials (carbon black and reduced graphene oxide). The relative concentration of the rhodium and iridium cations in the synthetic media was varied allowing for different metal ratios on the carbon surfaces. The composition of the complexes bound to the surfaces was confirmed using XPS which revealed the relative ratios of the iridium and the rhodium species on the surface, agreeing well with the values obtained by MP-AES. The materials were further characterized by N 2 absorption. The qualitative distribution of rhodium and iridium ions on the carbon surfaces was determined by STEM-EDX, revealing a uniform distribution of both complexes on the carbon surfaces. The efficiency of the materials as catalysts for intramolecular hydroamination was investigated. The data acquired demonstrated that the optimized ratio of rhodium and iridium on the carbon black material led to more effective catalysts than their monometallic counterparts. Having both complexes on the same carbon black surface presented an improvement in the catalytic activity compared to the complexes immobilized on separate particles
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