Comparing α7 nicotinic acetylcholine receptor binding,amyloid‐β deposition,and mitochondria complex‐I function in living brain: A PET study in aged monkeys

This study was aimed to assess the correlations among α7 nicotinic acetylcholine receptor (α7‐nAChR) binding, amyloid‐β (Aβ) deposition, and mitochondrial complex I (MC‐I) activity in the brain of aged monkeys (Macaca mulatta). Positron emission tomography (PET) measurements with [¹¹C](R)‐MeQAA, [¹¹C]PIB, and [¹⁸F]BCPP‐EF were conducted in monkeys in a conscious condition. [¹¹C](R)‐MeQAA binding was analyzed by a simplified reference tissue model to calculate nondisplaceable binding potential (BP_ND), [¹¹C]PIB uptake was calculated by standard uptake value ratio (SUVR), and [¹⁸F]BCPP‐EF binding was determined by Logan graphical analysis to calculate total distribution volume (V_T) with arterial blood sampling. Higher brain uptake was determined in the thalamus, hippocampus, striatum, and cortical regions for [¹¹C](R)‐MeQAA, while being lower in the cerebellum. Significant age‐related reduction of [¹¹C](R)‐MeQAA binding to α7‐nAChR was determined only in the occipital cortex. The plot of Vt of [¹⁸F]BCPP‐EF against BP_ND of [¹¹C](R)‐MeQAA indicated a significant negative correlation in the hippocampus and cortical regions in aged animals. Plotting of SUVR of [¹¹C]PIB against BP_ND of [¹¹C](R)‐MeQAA showed a positive correlation. The in vivo binding of [¹¹C](R)‐MeQAA could reflect the upregulation of α7‐nAChR induced by neurodegenerative damage determined by Aβ deposition as well as impaired MC‐I activity in living brain. Synapse 69:475–483, 2015. © 2015 Wiley Periodicals, Inc.     

AT2R deficiency mediated podocyte loss via activation of ectopic hedgehog interacting protein (Hhip) gene expression

Angiotensin II type 2 receptor (AT₂R) deficiency in AT₂R knockout (KO) mice has been linked to congenital abnormalities of the kidney and urinary tract; however, the mechanisms by which this occurs are poorly understood. In this study, we examined whether AT₂R deficiency impaired glomerulogenesis and mediated podocyte loss/dysfunction in vivo and in vitro. Nephrin‐cyan fluorescent protein (CFP)‐transgenic (Tg) and Nephrin/AT₂RKO mice were used to assess glomerulogenesis, while wild‐type and AT₂RKO mice were used to evaluate maturation of podocyte morphology/function. Immortalized mouse podocytes (mPODs) were employed for in vitro studies. AT₂R deficiency resulted in diminished glomerulogenesis in E15 embryos, but had no impact on actual nephron number in neonates. Pups lacking AT₂R displayed features of renal dysplasia with lower glomerular tuft volume and podocyte numbers. In vivo and in vitro studies demonstrated that loss of AT₂R was associated with elevated NADPH oxidase 4 levels, which in turn stimulated ectopic hedgehog interacting protein (Hhip) gene expression in podocytes. Consequently, ectopic Hhip expression activation either triggers caspase‐3 and p53‐related apoptotic processes resulting in podocyte loss, or activates TGFβ1–Smad2/3 cascades and α‐SMA expression to transform differentiated podocytes to undifferentiated podocyte‐derived fibrotic cells. We analyzed HHIP expression in the kidney disease database (Nephroseq) and then validated this using HHIP immunohistochemistry staining of human kidney biopsies (controls versus focal segmental glomerulosclerosis). In conclusion, loss of AT₂R is associated with podocyte loss/dysfunction and is mediated, at least in part, via augmented ectopic Hhip expression in podocytes. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

New Poly[(R)‐3‐hydroxybutyrate‐co‐4‐hydroxybutyrate] (P3HB4HB)‐Based Thermogels

Poly[(R )‐3‐hydroxybutyrate] (P3HB) is a potential candidate for biomaterials due to its biocompatibility and biodegradability. However, P3HB needs to have tunable hydrophobicity, modification through chemical functionalization and the right hydrolytic stability to increase their potential for water‐based biomedical applications such as using them as in situ forming gels for drug delivery. This work focuses on using a copolymer, poly[(R )‐3‐hydroxybutyrate‐co‐4‐hydroxybutyrate] (P3HB4HB) in a thermogelling multiblock system with polypropylene glycol and polyethylene glycol to study the effect of the hydrophobic P3HB4HB on gelation properties, degradation, and drug release rates with reference to P3HB. Thermogels containing P3HB4HB segments show lower critical micellization concentration values in a range from 3 × 10⁻⁴ to 1.08 × 10⁻³ g mL⁻¹ and lower critical gelation concentration values ranging from 2 to 6 wt% than that of gels containing P3HB. Furthermore, gels containing P3HB4HB degrade at a slower rate than the gels containing P3HB. Drug release studies of 5 µg mL⁻¹ of doxorubicin show that gels containing P3HB4HB exhibit sustained release although the release rates are faster than gels containing P3HB. However, this can be modified by varying the concentration of the gels used. Process optimization of purifying the starting material is one important factor before the synthesis of these biomaterials.

     

TarSeqQC: Quality control on targeted sequencing experiments in R

Targeted sequencing (TS) is growing as a screening methodology used in research and medical genetics to identify genomic alterations causing human diseases. In general, a list of possible genomic variants is derived from mapped reads through a variant calling step. This processing step is usually based on variant coverage, although it may be affected by several factors. Therefore, undercovered relevant clinical variants may not be reported, affecting pathology diagnosis or treatment. Thus, a prior quality control of the experiment is critical to determine variant detection accuracy and to avoid erroneous medical conclusions. There are several quality control tools, but they are focused on issues related to whole‐genome sequencing. However, in TS, quality control should assess experiment, gene, and genomic region performances based on achieved coverages. Here, we propose TarSeqQC R package for quality control in TS experiments. The tool is freely available at Bioconductor repository. TarSeqQC was used to analyze two datasets; low‐performance primer pools and features were detected, enhancing the quality of experiment results. Read count profiles were also explored, showing TarSeqQC's effectiveness as an exploration tool. Our proposal may be a valuable bioinformatic tool for routinely TS experiments in both research and medical genetics.     

IFN‐γR1 defects: Mutation update and description of the IFNGR1 variation database

IFN‐γ signaling is essential for the innate immune defense against mycobacterial infections. IFN‐γ signals through the IFN‐γ receptor, which consists of a tetramer of two IFN‐γR1 chains in complex with two IFN‐γR2 chains, where IFN‐γR1 is the ligand‐binding chain of the interferon‐γ receptor and IFN‐γR2 is the signal‐transducing chain of the IFN‐γ receptor. Germline mutations in the gene IFNGR1 encoding the IFN‐γR1 cause a primary immunodeficiency that mainly leads to mycobacterial infections. Here, we review the molecular basis of this immunodeficiency in the 130 individuals described to date, and report mutations in five new individuals, bringing the total number to 135 individuals from 98 kindreds. Forty unique IFNGR1 mutations have been reported and they exert either an autosomal dominant or an autosomal recessive effect. Mutations resulting in premature stopcodons represent the majority of IFNGR1 mutations (60%; 24 out of 40), followed by amino acid substitutions (28%, 11 out of 40). All known mutations, as well as 287 other variations, have been deposited in the online IFNGR1 variation database ( www.LOVD.nl/IFNGR1 ). In this article, we review the function of IFN‐γR1 and molecular genetics of human IFNGR1.