Evaluation of xenobiotic N- and S-oxidation by variant flavin-containing monooxygenase 1 (FMO1) enzymes.

The flavin-containing monooxygenase gene family (FMO1-6) in humans encodes five functional isoforms that catalyze the monooxygenation of numerous N-, P- and S-containing drugs and toxicants. A previous single nucleotide polymorphism (SNP) analysis of FMO1 in African-Americans identified seven novel SNPs. To determine the functional relevance of the coding FMO1 variants (H97Q, I303V, I303T, R502X), they were heterologously expressed using a baculovirus system. Catalytic efficiency and stereoselectivity of N- and S-oxygenation was determined in the FMO1 variants using several substrates. The I303V variant showed catalytic constants equal to wild-type FMO1 for methimazole and methyl p-tolyl sulfide. Catalytic efficiency (V(max)/K(m)) of methyl p-tolyl sulfide oxidation by R502X was unaltered. In contrast, methimazole oxidation by R502X was not detected. Both H97Q and I303T had elevated catalytic efficiency with regards to methyl p-tolyl sulfide (162% and 212%, respectively), but slightly reduced efficiency with regards to methimazole (81% and 78%). All the variants demonstrated the same stereoselectivity for methyl p-tolyl sulfide oxidation as wild-type FMO1. FMO1 also metabolized the commonly used insecticide fenthion to its (+)-sulfoxide, with relatively high catalytic efficiency. FMO3 metabolized fenthion to its sulfoxide at a lower catalytic efficiency than FMO1 (27%) and with less stereoselectivity (74% (+)-sulfoxide). Racemic fenthion sulfoxide was a weaker inhibitor of acetylcholinesterase than its parent compound (IC(50) 0.26 and 0.015 mM, respectively). The (+)- and (-)-sulfoxides were equally potent inhibitors of acetylcholinesterase. These data indicate that all the currently known FMO1 variants are catalytically active, but alterations in kinetic parameters were observed.     

Fast forward to new genes in mammalian reproduction

The study of reproductive genetics in mammals has lagged behind that of simpler and more tractable model organisms, such as D. melanogaster , C. elegans and various yeast models. Although much valuable information has been generated using these organisms, they do not model the genetic and biological complexity of mammalian reproduction. Thus, the majority of genes required for gametogenesis in mammals remain unidentified. To expand on the existing knowledge of mammalian reproductive genetics, we have carried out forward genetic screens in mice to identify infertility mutants and the underlying mutant genes. Two different approaches were used: mutagenesis of the germline in whole mice, and mutagenesis of embryonic stem cells. This was followed by two- or three-generation breeding schemes to identify pedigrees segregating infertility mutations, which were then phenotypically characterized, genetically mapped, and in some cases, positionally cloned. This whole-genome approach has generated a wide collection of mutants with defects ranging from problems with germ cell development to abnormal sperm morphology. These models have allowed us to study the genetics, as well as the physiology, of reproduction in mammals. This review focuses on describing some of the genes identified in these screens and the ongoing effort to characterize additional mutants.     

Bursts of high-frequency stimulation trigger rapid delivery of pre-existing alpha-CaMKII mRNA to synapses: a mechanism in dendritic protein synthesis during long-term potentiation in adult awake rats

Messenger ribonucleic acid encoding the alpha-subunit of calcium/calmodulin-dependent protein kinase II (camkII) is abundantly and constitutively expressed in dendrites of pyramidal and granule cell neurons of the adult hippocampus. Recent evidence suggests that camkII messenger ribonucleic acid is stored in a translationally dormant state within ribonucleic acid storage granules. Delivery of camkII messenger ribonucleic acid from sites of storage to sites of translation may therefore be a key step in activity-driven dendritic protein synthesis and synaptic plasticity. Here we explored possible camkII trafficking in the context of long-term potentiation in the dentate gyrus of awake, adult rats. Long-term potentiation was induced by patterned high-frequency stimulation, synaptodendrosomes containing pinched-off dendritic spines were obtained from microdissected dentate gyrus, and messenger ribonucleic acid levels were determined by real-time polymerase chain reaction. High-frequency stimulation triggered a rapid 2.5-fold increase in camkII messenger ribonucleic acid levels in the synaptodendrosome fraction. This increase occurred in the absence of camkII upregulation in the homogenate fraction, indicating trafficking of pre-existing messenger ribonucleic acid to synaptodendrosomes. The elevation in camkII messenger ribonucleic acid was paralleled by an increase in protein expression specific to the synaptodendrosome fraction, and followed by depletion of camkII message. Activity-dependent regulation of camkII messenger ribonucleic acid and protein did not require N-methyl-d-aspartate receptor activation. In contrast, N-methyl-d-aspartate receptor activation was required for induction of the immediate early genes zif268 and activity-regulated cytoskeleton-associated protein in dentate gyrus homogenates. The results support a model in which locally stored camkII messenger ribonucleic acid is rapidly transported to dendritic spines and translated during long-term potentiation in behaving rats.     

The Use of Solvent/Detergent Treatment in Pathogen Reduction of Plasma

The solvent/detergent (SD) process used for plasma can safely inactivate all lipid-enveloped viruses. The introduction of a specific prion-binding ligand gel in combination with SD treatment, time-reduced from 4 to 1-1.5 h, still ensures efficient virus kill, reduces abnormal prion protein by >5 log steps, and preserves levels of plasmin inhibitor at close to the reference range. Infections with known non-enveloped viruses such as HAV or parvovirus B19 are prevented by ensuring low virus loads in the starting plasma units, dilution through pooling of single plasma units, and neutralization of immune antibodies already present in the initial plasma pools. The major advantages of SD plasma over fresh frozen plasma and the other pathogen-inactivated plasmas are its extreme safety with respect to transfusion-related acute lung injury and the significantly lower likelihood of provoking allergic reactions. Both advantages are best interpreted as results of the dilution effect of pooling. No fewer than 18 clinical studies covering all indications for plasma, and extensive clinical experience have shown that reduced levels of coagulation factors and inhibitors as a result of SD treatment do not impair significantly the clinical efficacy or tolerance of plasma. Properly standardized clotting factor and inhibitor potencies and low batch-to-batch variations when compared with single-donor plasma units makes SD plasma more suitable for standardized treatment.     

Subjects with familial hypercholesterolemia have lower aortic valve area and higher levels of inflammatory biomarkers

BackgroundReduction of the aortic valve area (AVA) may lead to aortic valve stenosis with considerable impact on morbidity and mortality if not identified and treated. Lipoprotein (a) [Lp(a)] and also inflammatory biomarkers, including platelet derived biomarkers, have been considered risk factor for aortic stenosis; however, the association between Lp(a), inflammatory biomarkers and AVA among patients with familial hypercholesterolemia (FH) is not clear.ObjectiveWe aimed to investigate the relation between concentration of Lp(a), measurements of the aortic valve including velocities and valve area and circulating inflammatory biomarkers in adult FH subjects and controls.MethodsIn this cross-sectional study aortic valve measures were examined by cardiac ultrasound and inflammatory markers were analyzed in non-fasting blood samples. The study participants were 64 FH subjects with high (n = 29) or low (n = 35) Lp(a), and 14 healthy controls.ResultsAortic valve peak velocity was higher (p = 0.02), and AVA was lower (p = 0.04) in the FH patients compared to controls; however, when performing multivariable linear regression, there were no significant differences. Furthermore, there were no significant differences between the high and low FH Lp(a) groups regarding the aortic valve. FH subjects had higher levels of platelet-derived markers CD40L, PF4, NAP2 and RANTES compared to controls (0.003 ≤ P ≤ 0.03). This result persisted after multiple linear regression.ConclusionsMiddle-aged, intensively treated FH subjects have higher aortic valve velocity, lower AVA, and higher levels of the platelet-derived markers CD40L, PF4, NAP2 and RANTES compared to healthy control subjects. The aortic valve findings were not significant after multiple linear regression, whereas the higher levels of platelet-derived markers were maintained.     

Donor lymphocytes transferred with the graft to kidney recipients. Potential for establishing microchimerism.

After solid organ transplantation donor lymphocytes have been shown to survive and multiply in the organ recipient for a prolonged period. It is not clear whether this chimerism detected is the result of immunosuppression or the cause of allograft acceptance. The number of cells transferred, as well as the type of cells, and the degree of activation are likely to be of importance for the establishment of microchimerism. The cells that are flushed out of the vascular tree may be of particular importance since when an antigen primarily bypasses or secondarily avoids organised lymphoid collections, the immune system in the recipient may remain or become "indifferent" to its presence. In the present study we examined the amount of residual donor blood cells that we could flush out from the vascular tree of living donor kidneys and cadaveric donor kidneys immediately prior to transplantation, with special emphasis on T and B lymphocytes. Our study shows that perfusion of donor kidneys just prior to transplantation releases from 0.1 to 1.8x10(6) B-lymphocytes, with an average of 0.7x10(6) and from 0.5x10(6) to 2.6x10(6) T-lymphocytes, with an average of 1.8x10(6), for CD kidneys, and somewhat less for LD kidneys. These cells would otherwise have been flushed out into the organ recipient's circulation, where they might play a role in the establishment of microchimerism.     

HLA variants related to primary sclerosing cholangitis influence rejection after liver transplantation

AIM:To investigate influence of human leukocyte antigen(HLA)and killer immunoglobuline-like receptor(KIR)genotypes on risks of acute rejection(AR)after liver transplantation(LTX).METHODS:In this retrospective study we included143 adult donor-recipient pairs with a minimum of 6mo follow-up after LTX for whom DNA was available from both donor and recipients.Clinical data,all early complications including episodes and severity of AR and graft/patient survival were registered.The diagnosis of AR was based on clinical,biochemical and histological criteria.All suspected episodes of AR were biopsy confirmed.Key classical HLA loci(HLA-A,HLA-B,HLA-C and HLA-DRB1)were genotyped using Sanger sequencing.16 KIR genes were genotyped using a novel real time PCR approach which allows for determination of the diploid copy number of each KIR gene.Immunohistochemical staining for T(CD3),B(CD20)and natural killer(NK)cells(CD56 and CD57)were performed on liver biopsies from 3 different patient groups[primary sclerosing cholangitis(PSC),primary biliary cirrhosis and non-autoimmune liver disease],10 in each group,with similar grade of AR.RESULTS:Fourty-four(31%)patients were transplanted on the basis of PSC,40%of them had AR vs 24%in the non-PSC group(P=0.04).No significant impact of donor-recipient matching for HLA and KIR genotypes was detected.In the overall recipient population an increased risk of AR was detected for HLA-B*08(P=0.002,OR=2.5;95%CI:1.4-4.6),HLA-C*07(P=0.001,OR=2.4;95%CI:1.4-4.0)and HLA-DRB1*03(P=0.03,OR=1.9;95%CI:1.0-3.3)and a decreased risk for HLA-DRB1*04(P=0.001,OR=0.2;95%CI:0.1-0.5).For HLA-B*08,HLA-C*07 and DRB1*04 the associations remained evident in a subgroup analysis of non-PSC recipients(P=0.04,P=0.003 and P=0.02,respectively).In PSC recipients corresponding P values were 0.002,0.17 and 0.01 for HLA-B*08,HLA-C*07and DRB1*04,respectively.A dosage effect of AR prevalence according to the PSC associated HLA alleles was also notable in the total recipient population.For HLA-B*08 the frequency of AR was 56%in HLA-B*08homozygous recipients,39%in heterozygous recipients and 21%in recipients lacking HLA-B*08(P=0.02).The same was observed for the HLA-C*07 allele with AR in 57%,27%and 18%in recipients being homozygous,heterozygous and lacking HLA-C*07 respectively(P=0.003).Immunohistochemical analysis showed similar infiltration of T,B and NK cells in biopsies with AR in all three groups.CONCLUSION:We found significant associations between the PSC-associated HLA-B*08,HLA-C*07,HLADRB1*03 and HLA-DRB1*04 alleles and risk of AR in liver transplant recipients.