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• Silent Alzheimer's disease impacts hypothalamus and hippocampus transcriptome. • AppNL-G-F mice show change in several biomarkers prior to cognitive decline. • Leptin levels are decreased during silent phase of Alzheimer's in AppNL-G-F mice. • Inflammatory mediators are increased during silent phase in AppNL-G-F mice. • Transcriptome changes during the silent phase persists during active disease phase. The progression of Alzheimer's disease (AD) has a silent phase that predates characteristic cognitive decline and eventually leads to active cognitive deficits. Metabolism, diet, and obesity have been correlated to the development of AD but is poorly understood. The hypothalamus is a brain region that exerts homeostatic control on food intake and metabolism and has been noted to be impacted during the active phase of Alzheimer's disease. This study, in using an amyloid overexpression AppNL-G-F mouse model under normal metabolic conditions, examines blood markers in young and old male AppNL-G-F mice (n = 5) that corresponds to the silent and active phases of AD, and bulk gene expression changes in the hypothalamus and the hippocampus. The results show a large panel of inflammatory mediators, leptin, and other proteins that may be involved in weakening the blood brain barrier, to be increased in the young AppNL-G-F mice but not in the old AppNL-G-F mice. There were also several differentially expressed genes in both the hypothalamus and the hippocampus in the young AppNL-G-F mice prior to amyloid plaque formation and cognitive decline that persisted in the old AppNL-G-F mice, including GABRa2 receptor, Wdfy1, and several pseudogenes with unknown function. These results suggests that a larger panel of inflammatory mediators may be used as blood markers to detect silent AD, and that a change in leptin and gene expression in the hypothalamus exist prior to cognitive effects, suggesting a coupling of metabolism with amyloid plaque induced cognitive decline. [ABSTRACT FROM AUTHOR]

In this note, we study the fast solution of Toeplitz linear systems with coefficient matrix T n ( f ) , where the generating function f is nonnegative and has a unique zero at zero of any real positive order θ . As preconditioner we choose a matrix τ n ( f ) belonging to the so-called τ algebra, which is diagonalized by the sine transform associated to the discrete Laplacian. In previous works, the spectral equivalence of the matrix sequences { τ n ( f ) } n and { T n ( f ) } n was proven under the assumption that the order of the zero is equal to 2: in other words the preconditioned matrix sequence { τ n − 1 ( f ) T n ( f ) } n has eigenvalues, which are uniformly away from zero and from infinity. Here we prove a partial generalization of the above result when θ < 2 . Furthermore, by making use of multiple step preconditioning, we show that the matrix sequences { τ n ( f ) } n and { T n ( f ) } n are essentially spectrally equivalent for every θ > 2 , i.e., for every θ > 2 , there exist m θ and a positive interval [ α θ , β θ ] such that all the eigenvalues of { τ n − 1 ( f ) T n ( f ) } n belong to this interval, except at most m θ outliers larger than β θ : while the essential bound from above is proven, the bound from below is only observed numerically. Such a nice property, already known only when θ is an even positive integer greater than 2, is coupled with the fact that the preconditioned sequence has an eigenvalue cluster at one, so that the convergence rate of the associated preconditioned conjugate gradient method is optimal. As a conclusion we discuss possible generalizations and we present selected numerical experiments. [ABSTRACT FROM AUTHOR]

Abstract: We extend here the Perron–Frobenius theory of nonnegative matrices to certain complex matrices. Following the generalization of the Perron–Frobenius theory to matrices that have some negative entries, given by Noutsos , we introduce here two types of extensions of the Perron–Frobenius theory to complex matrices. We present and prove here some sufficient conditions and some necessary and sufficient conditions for a complex matrix to have a Perron–Frobenius eigenpair. We apply this theory by introducing Perron–Frobenius splittings, as well as complex Perron–Frobenius splittings, for the solution of complex linear systems , by classical iterative methods. Perron–Frobenius splittings constitute an extension of the well-known regular splittings, weak regular splittings and nonnegative splittings. Convergence and comparison properties are also given and proved. [Copyright &y& Elsevier]

Abstract: Given an real matrix A with nonnegative off-diagonal entries, the solution to , , is . The problem of identifying the initial points for which becomes and remains entrywise nonnegative is considered. It is known that such are exactly those vectors for which the iterates become and remain nonnegative, where h is a positive, not necessarily small parameter that depends on the diagonal entries of A. In this paper, this characterization of initial points is extended to a numerical test when A is irreducible: if becomes and remains positive, then so does ; if fails to become and remain positive, then either becomes and remains negative or it always has a negative and a positive entry. Due to round-off errors, the latter case manifests itself numerically by converging with a relatively small convergence ratio to a positive or a negative vector. An algorithm implementing this test is provided, along with its numerical analysis and examples. The reducible case is also discussed and a similar test is described. [Copyright &y& Elsevier]

Abstract: The Stein–Rosenberg theorem is extended and generalized to the class of nonnegative splittings , as well as to the most generalized class of Perron–Frobenius splittings. Two types of the Stein–Rosenberg theorem are stated and proved for both classes. These theorems allow us to obtain comparison results for the rate of convergence of the associated iterative methods. Specific assumptions are given under which the inequalities of the spectral radii become equalities or strict inequalities. The theoretical results are confirmed by numerical examples. [Copyright &y& Elsevier]

Abstract: The paper studies fast and efficient solution algorithms for symmetric ill conditioned Toeplitz systems where the generating function is known a priori, real valued, nonnegative, and has isolated roots of even order. The preconditioner that we propose is a product of a band Toeplitz matrix and matrices that belong to a certain trigonometric algebra. The basic idea behind the proposed scheme is to combine the advantages of all components of the product that are well known when every component is used as a stand-alone preconditioner. As a result we obtain a flexible preconditioner which can be applied to the system infusing superlinear convergence to the PCG method. The important feature of the proposed technique is that it can be extended to cover the case, i.e. ill-conditioned block Toeplitz matrices with Toeplitz blocks. We perform many numerical experiments, whose results confirm the theoretical analysis and effectiveness of the proposed strategy. [Copyright &y& Elsevier]

Abstract: In this paper we are concerned with the study of spectral properties of the sequence of matrices coming from the discretization, using centered finite differences of minimal order, of elliptic (or semielliptic) differential operators of the form where the nonnegative, bounded coefficient function of the differential operator may have some isolated zeros in . More precisely, we state and prove the explicit form of the inverse of and some formulas concerning the relations between the orders of zeros of and the asymptotic behavior of the minimal eigenvalue (condition number) of the related matrices. As a conclusion, and in connection with our theoretical findings, first we extend the analysis to higher order (semi-elliptic) differential operators, and then we present various numerical experiments, showing that similar results must hold true in 2D as well. [Copyright &y& Elsevier]

Recent nuclear transfer of organellar DNA is thought to result mainly in nonfunctional nuclear sequences or in genetic dysfunction. Here we show that nuclear exons encoding novel protein sequences can be generated by insertions of organellar DNA. Most of the protein sequences do not correspond to preexisting organellar coding sequences or they represent markedly reshaped protein domains, reflecting the recruitment and adaptation of encoded proteins to new functions. Organelle-derived DNA insertions might be responsible for many more ancient functional exon acquisitions that are not directly detectable. [Copyright &y& Elsevier]

Abstract: We extend the theory of nonnegative matrices to the matrices that have some negative entries. We present and prove some properties which give us information, when a matrix possesses a Perron–Frobenius eigenpair. We apply also this theory by proposing the Perron–Frobenius splitting for the solution of the linear system Ax = b by classical iterative methods. Perron–Frobenius splittings constitute an extension of the well known regular splittings, weak regular splittings and nonnegative splittings. Convergence and comparison properties are given and proved. [Copyright &y& Elsevier]

Abstract: In this note we give condition number estimates for two-level Toeplitz matrices generated by bivariate 2π-periodic weakly sectorial symbols (the largest class of symbols for which we can guarantee the invertibility of all the corresponding Toeplitz matrices). By using and extending tools previously developed in the one-level context, we show that the asymptotical ill-conditioning is essentially related to the order of zeros of the symbol. [Copyright &y& Elsevier]

In the last four decades many articles have been devoted to the modifications and improvements of classes of preconditioners for linear systems whose matrix coefficient is an M-matrix in order to improve on the convergence rates of the classical iterative schemes (Jacobi, Gauss–Seidel, etc.). The present work is a contribution towards the generalization of the most common preconditioners used so far. [Copyright &y& Elsevier]

Limited evidence exists on the distribution of ABO RhD blood groups and prevalence and specificity of red blood cell (RBC) alloantibodies in Aboriginal and Torres Strait Islander peoples of Australia. We investigated RBC alloantibody prevalence and ABO RhD groups in Aboriginal patients undergoing cardiac surgery at a South Australian (SA) tertiary hospital, a major cardiac surgical referral centre for Northern Territory (NT) patients Retrospective analysis of all consecutive patients undergoing cardiac surgery at Flinders Medical Centre (FMC) between January 2014 and June 2019. ABO and RhD blood groups, and RBC alloantibody prevalence, specificity, and clinical significance in Aboriginal and non-Aboriginal cardiac patients were determined at time of surgery and on follow up to 2021. 2327 patients were included, 588 (25.3 %) were from NT, and 420 (18.0 %) were Aboriginal. Aboriginal patients had a higher prevalence of ABO group O (59.8 % vs 43.9 %) and RhD positive (99.0 % vs 83.8 %). One-hundred-and-eleven patients had 154 RBC alloantibodies, 57/420 (13.6 %) Aboriginal versus 54/1907 (2.8 %) non-Aboriginal (p < 0.0001). There were higher numbers of IgM alloantibodies in Aboriginal patients (59/77, 76.6 %), with Lewis, P1 and M more common. Sixty patients had antibodies detected at time of surgery, 14 NT patients with previously detected alloantibodies, prior to surgery, presented with a negative antibody screen and 37 had new antibodies detected after cardiac surgery. A high prevalence of IgM alloantibodies was found in Aboriginal compared to non-Aboriginal cardiac surgery patients. The clinical significance of these IgM alloantibodies in Aboriginal peoples requires further investigation. [ABSTRACT FROM AUTHOR]

Prenatal high-fat diet exposure increases hypothalamic neurogenesis events in embryos and programs offspring to be obesity-prone. The molecular mechanism involved in these dietary effects of neurogenesis is unknown. This study investigated the effects of oleic and palmitic acids, which are abundant in a high-fat diet, on the hypothalamic neuronal transcriptome and how these changes impact neurogenesis events. The results show the differential effects of low and high concentrations of oleic or palmitic acid treatment on differential gene transcription. Gene ontology analysis uncovered significant gene enrichment in several cellular pathways involved in gene regulation and protein production, particularly with proliferation, migration, and cell survival. The enriched signaling pathways include Wnt, integrin, PDGF, and apoptosis, in addition to endocrine function signaling pathways CCKR and GnRH. Further examination of proliferation and migration shows low concentrations of oleic acid to stimulate proliferation and high concentrations of both oleic and palmitic acid to stimulate apoptosis. Oleic acid also reduces hypothalamic neuronal migration, with little effect from palmitic acid. The results show the two most abundant fatty acids in a high-fat diet impact hypothalamic neuronal proliferation and migration. The results also uncovered potential signaling pathways affected by oleic and palmitic acid and suggest one mechanism of prenatal high-fat diet-induced neurogenesis events may be through these two abundant fatty acids. [ABSTRACT FROM AUTHOR]

Abstract: Post-endosymbiotic evolution of the proto-chloroplast was characterized by gene transfer to the nucleus. Hence, most chloroplast proteins are nuclear-encoded and the regulation of chloroplast functions includes nuclear transcriptional control. The expression profiles of 3292 nuclear Arabidopsis genes, most of them encoding chloroplast proteins, were determined from 101 different conditions and have been deposited at the GEO database (http://www.ncbi.nlm.nih.gov/geo/) under GSE1160–GSE1260 GSE1160 GSE1161 GSE1162 GSE1163 GSE1164 GSE1165 GSE1166 GSE1167 GSE1168 GSE1169 GSE1170 GSE1171 GSE1172 GSE1173 GSE1174 GSE1175 GSE1176 GSE1177 GSE1178 GSE1179 GSE1180 GSE1181 GSE1182 GSE1183 GSE1184 GSE1185 GSE1186 GSE1187 GSE1188 GSE1189 GSE1190 GSE1191 GSE1192 GSE1193 GSE1194 GSE1195 GSE1196 GSE1197 GSE1198 GSE1199 GSE1200 GSE1201 GSE1202 GSE1203 GSE1204 GSE1205 GSE1206 GSE1207 GSE1208 GSE1209 GSE1210 GSE1211 GSE1212 GSE1213 GSE1214 GSE1215 GSE1216 GSE1217 GSE1218 GSE1219 GSE1220 GSE1221 GSE1222 GSE1223 GSE1224 GSE1225 GSE1226 GSE1227 GSE1228 GSE1229 GSE1230 GSE1231 GSE1232 GSE1233 GSE1234 GSE1235 GSE1236 GSE1237 GSE1238 GSE1239 GSE1240 GSE1241 GSE1242 GSE1243 GSE1244 GSE1245 GSE1246 GSE1247 GSE1248 GSE1249 GSE1250 GSE1251 GSE1252 GSE1253 GSE1254 GSE1255 GSE1256 GSE1257 GSE1258 GSE1259 GSE1260 . The 1590 most-regulated genes fell into 23 distinct groups of co-regulated genes (regulons). Genes of some regulons are not evenly distributed among the five Arabidopsis chromosomes and pairs of adjacent, co-expressed genes exist. Except regulons 1 and 2, regulons are heterogeneous and consist of genes coding for proteins with different subcellular locations or contributing to several biochemical functions. This implies that different organelles and/or metabolic pathways are co-ordinated at the nuclear transcriptional level, and a prototype for this is regulon 12 which contains genes with functions in amino acid and carbohydrate metabolism, as well as genes associated with transport or transcription. The co-expression of nuclear genes coding for subunits of the photosystems or encoding proteins involved in the transcription/translation of plastome genes (particularly ribosome polypeptides) (regulons 1 and 2, respectively) implies the existence of a novel mechanism that co-ordinates plastid and nuclear gene expression and involves nuclear control of plastid ribosome abundance. The co-regulation of genes for photosystem and plastid ribosome proteins escapes a previously described general control of nuclear chloroplast proteins imposed by a transcriptional master switch, highlighting a mode of transcriptional regulation of photosynthesis which is different compared to other chloroplast functions. From the evolutionary standpoint, the results provided indicate that functional integration of the proto-chloroplast into the eukaryotic cell was associated with the establishment of different layers of nuclear transcriptional control. [Copyright &y& Elsevier]