ABO-adjusted cPRA metric for kidney allocation in an Asian-predominant population.

Recent studies showed that ABO-adjusted calculated panel reactive antibody (ABO-cPRA) may better reflect the histocompatibility level in a multi-ethnic population, but such data in Asians is not available. We developed an ABO-adjusted cPRA metric on a cohort of waitlist kidney transplant patients (n = 647, 99% Chinese) in Hong Kong, based on HLA alleles and ABO frequencies of local donors. The concordance between the web-based ABO-cPRA calculator and the impact on kidney allocation were evaluated. The blood group distribution for A, B, O and AB among waitlist kidney candidates were 26.2%, 27.5%, 40.1%, and 6.1%, and their chances of encountering incompatible blood group donors were 32.6%, 32.4%, 57.6%, and 0%, respectively. There is poor agreement between web-based ABO-cPRA calculator and our locally developed metrics. Over 90% of patients showed an increase in cPRA after ABO adjustment, most notably in those with cPRA between 70% and 79%. Blood group O patients had a much greater increase in cPRA scores after adjustment while patients of blood group A and B had similar increment. 10.6% of non-AB blood group waitlist patients had ABO-cPRA elevated to ≥80%. A local ABO-adjusted cPRA metric is required for Asian populations and may improve equity in kidney distribution for patients with disadvantageous blood groups. The result from the current study potentially helps other countries/localities in establishing their own unified ABO-cPRA metrics and predict the impact on kidney allocation.

A simplified method of calculating cPRA for kidney allocation application in Hong Kong: a retrospective study.

Calculated panel reactive antibody (cPRA) represents possibility of encountering an incompatible donor for organ transplant candidates and has gradually replaced traditional PRA as a measurement of sensitization level. We tested two cPRA calculation methods on a cohort of renal candidate (n = 613). HLA typing of 563 Chinese deceased renal donors was used to estimate allele and haplotype frequencies of Hong Kong donor pool. The OPTN formula was adopted to generate cPRA (cPRA (freq)). We also incorporated a computer script to compare unacceptable antigens of patients against HLA phenotype of donors. The cPRA based on historical donor filtering was the percentage of filter out count over total number of donors (cPRA (filter)). Values of cPRA (freq) and cPRA (filter) showed almost perfect agreement with Lin's correlation coefficient equal to 1.000. SD of bias was 0.6 cPRA point. Limit of agreement was 0.9 to -1.5 points difference. Furthermore, the poor agreement between our in-house cPRA and values from other online calculators indicated the necessity to use local population data for accurate cPRA calculation. Built-in donor filtering method was more practicable for Hong Kong due to factors such as cost and flexibility. An on-going donor pool can reflect population allele frequencies and permits efficient periodic update of cPRA.

Next-generation freshwater bioassessment: eDNA metabarcoding with a conserved metazoan primer reveals species-rich and reservoir-specific communities.

Freshwater habitats are of high conservation value and provide a wide range of ecosystem services. Effective management requires regular monitoring. However, conventional methods based on direct observation or specimen collection are so invasive, expensive and labour-intensive that frequent monitoring is uncommon. Here, we test whether the evaluation of environmental DNA (eDNA) from water based on a simple protocol can be used for assessing biodiversity. We use universal metazoan primers for characterizing water eDNA across horizontal and vertical spatial dimensions in two reservoirs with known species diversity for two key taxa. eDNA obtained directly from 42 samples × 15 ml water (total = 630 ml) per reservoir yielded DNA signatures for more than 500 metazoan species, of which 105 could be identified to species/genus based on DNA barcodes. We show that eDNA can be used to assign each water sample to its reservoir of origin, and that eDNA outperforms conventional survey methods in single-sample richness comparisons, while revealing evidence for hundreds of unknown species that are undetected by conventional bioassessment methods. eDNA also confirms the presence of a recently discovered invasive snail species and provides evidence for the continued survival of a rare native species of goby not sighted in that habitat since 2007. eDNA thus promises to be a useful addition to the bioassessment toolbox for freshwater systems.

Selection of chiral zinc catalysts for the kinetic resolution of esters via dynamic templating.

Dynamic combinatorial libraries of chiral tetradentate bis-imine zinc(II) complexes have been prepared and screened for (1) their discrimination of enantiomeric picolinate esters and pyridyl phosphonate transition state analogs (TSAs) and (2) their catalytic activity and selectivity for enantioselective methanolysis of racemic picolinate esters. The zinc complexes are in equilibrium with their imine ligands as well as with the aldehyde and amine building blocks that form them, enabling the composition of the library to adapt in response to the introduction of coordinating substrates or TSAs. Binary (L)Zn(OTf)(solv)(+) complexes are generated either individually or in libraries from chiral tartrate-derived diamines (2,3) and a set of N-heterocyclic aldehydes (4-12) and the distribution of complexes established by ESI-MS analysis. Binding studies of the (diimine)Zn(OTf)(2) complex libraries with enantiomeric R- and S-2-pyridyl phosphonate TSA 13 show chiral discrimination via formation of diastereomeric LZn(R/S-13)(+) complexes with low to moderate enatioselectivity ratios, k(R)/k(S) (α), ranging from 0.5 to 5.0; corresponding templating of selected binary complexes with the enantiomeric substrates, PyrCO(2)CH(OH)Ph (1), show negligible chiral recognition. The rate constants for methanolysis of the R- and S-esters, PyrCO(2)CH(OH)Ph (1) catalyzed by several L*Zn(OTf)(2) complexes range in value several fold depending on L and with enantioselectivity ratios, k(R)/k(S) (α), ranging from 0.76 to 2.8.

Tripodal bis(imidazole) thioether copper(I) complexes: mimics of the Cu(B) site of hydroxylase enzymes.

Tripodal bis(imidazole) thioether ligands and the corresponding copper(I) complexes [(BIMT-OR)Cu(L)]PF6 [L = CH3CN (2), CO (3); R = H (a), CH3 (b)] have been prepared as models for the Cu(B) site of copper hydroxylase enzymes. The IR (CO) values of 3a and 3b (L = CO) are comparable to those of the carbonylated enzymes. The reaction of 2a with O2 gives dinuclear complex 4 with bridging BIMT-O ligands and oxidized -SMe groups, whereas oxygenation of 2b affords [(BIMT-OMe)2Cu2O(H)2](CF3SO3)2 (5) and Cu(BIMT-OMe)(DMF)2](PF6)2 (6).

Catalysis research of relevance to carbon management: progress, challenges, and opportunities.

The goal of the "Opportunities for Catalysis Research in Carbon Management" workshop was to review within the context of greenhouse gas/carbon issues the current state of knowledge, barriers to further scientific and technological progress, and basic scientific research needs in the areas of H2 generation and utilization, light hydrocarbon activation and utilization, carbon dioxide activation, utilization, and sequestration, emerging techniques and research directions in relevant catalysis research, and in catalysis for more efficient transportation engines. Several overarching themes emerge from this review. First and foremost, there is a pressing need to better understand in detail the catalytic mechanisms involved in almost every process area mentioned above. This includes the structures, energetics, lifetimes, and reactivities of the species thought to be important in the key catalytic cycles. As much of this type of information as is possible to acquire would also greatly aid in better understanding perplexing, incomplete/inefficient catalytic cycles and in inventing new, efficient ones. The most productive way to attack such problems must include long-term, in-depth fundamental studies of both commercial and model processes, by conventional research techniques and, importantly, by applying various promising new physicochemical and computational approaches which would allow incisive, in situ elucidation of reaction pathways. There is also a consensus that more exploratory experiments, especially high-risk, unconventional catalytic and model studies, should be undertaken. Such an effort will likely require specialized equipment, instrumentation, and computational facilities. The most expeditious and cost-effective means to carry out this research would be by close coupling of academic, industrial, and national laboratory catalysis efforts worldwide. Completely new research approaches should be vigorously explored, ranging from novel compositions, fabrication techniques, reactors, and reaction conditions for heterogeneous catalysts, to novel ligands and ligation geometries (e.g., biomimetic), reaction media, and activation methods for homogeneous ones. The interplay between these two areas involving various hybrid and single-site supported catalyst systems should also be productive. Finally, new combinatorial and semicombinatorial means to rapidly create and screen catalyst systems are now available. As a complement to the approaches noted above, these techniques promise to greatly accelerate catalyst discovery, evaluation, and understanding. They should be incorporated in the vigorous international research effort needed in this field.