Microalbuminuria and hyperfiltration in subjects with nephro-urological disorders.

BACKGROUND: Microalbuminuria (MA) has been shown to be an early biomarker of renal damage. It is postulated that MA is the early result of hyperfiltration, which could evolve into glomerular sclerosis and renal failure if hyperfiltration is left untreated. We hypothesized that MA is a good indicator of hyperfiltration in children with kidney disorders, obviating the need to calculate the filtration fraction (FF). METHODS: A total of 155 children or young adults were prospectively included [42 single kidney (SK), 61 vesico-ureteral reflux, 23 obstructive uropathies, 29 other kidney diseases]. We measured inulin, para-aminohippuric acid clearances, FF and MA. Prediction of hyperfiltration was explored by studying the association between the FF and other variables such as urinary albumin (Alb), urinary albumin-creatinine ratio (ACR) and creatinine clearance. RESULTS: A significant but weak association between urinary Alb or ACR and FF was found in subjects with an SK (Spearman correlation coefficients 0.32 and 0.19, respectively). Multivariate analysis also showed that urinary Alb and ACR significantly predict FF only in subjects with an SK (r(2) = 0.17, P = 0.01 and r(2) = 0.13, P = 0.02, respectively). This holds true only in subjects with an SK and inulin clearance >90 mL/min/1.73 m(2) (r(2) = 0.41, P < 0.001). There was no association between creatinine clearance and FF. CONCLUSIONS: MA is not associated with FF in our subjects with nephro-urological disorders, except in those with an SK, where the association is weak, indicating that MA is due to other mechanisms than high FF and cannot predict hyperfiltration in such groups.

Functional compensation of motor function in pre-symptomatic Huntington's disease.

Involuntary choreiform movements are a clinical hallmark of Huntington's disease. Studies in clinically affected patients suggest a shift of motor activations to parietal cortices in response to progressive neurodegeneration. Here, we studied pre-symptomatic gene carriers to examine the compensatory mechanisms that underlie the phenomenon of retained motor function in the presence of degenerative change. Fifteen pre-symptomatic gene carriers and 12 matched controls performed button presses paced by a metronome at either 0.5 or 2 Hz with four fingers of the right hand whilst being scanned with functional magnetic resonance imaging. Subjects pressed buttons either in the order of a previously learnt 10-item finger sequence, from left to right, or kept still. Error rates ranged from 2% to 7% in the pre-symptomatic gene carriers and from 0.5% to 4% in controls, depending on the condition. No significant difference in task performance was found between groups for any of the conditions. Activations in the supplementary motor area (SMA) and superior parietal lobe differed with gene status. Compared with healthy controls, gene carriers showed greater activations of left caudal SMA with all movement conditions. Activations correlated with increasing speed of movement were greater the closer the gene carriers were to estimated clinical diagnosis, defined by the onset of unequivocal motor signs. Activations associated with increased movement complexity (i.e. with the pre-learnt 10-item sequence) decreased in the rostral SMA with nearing diagnostic onset. The left superior parietal lobe showed reduced activation with increased movement complexity in gene carriers compared with controls, and in the right superior parietal lobe showed greater activations with all but the most demanding movements. We identified a complex pattern of motor compensation in pre-symptomatic gene carriers. The results show that preclinical compensation goes beyond a simple shift of activity from premotor to parietal regions involving multiple compensatory mechanisms in executive and cognitive motor areas. Critically, the pattern of motor compensation is flexible depending on the actual task demands on motor control.

CD8beta knockout mice mount normal anti-viral CD8+ T cell responses--but why?

It has been shown previously that CD8beta in vitro increases the range and the sensitivity of antigen recognition and in vivo plays an important role in the thymic selection of CD8+ T cells. Consistent with this, we report here that CD8+ T cells from CD8beta knockout (KO) P14 TCR transgenic mice proliferate inefficiently in vitro. In contrast to these findings, we also show that CD8beta KO mice mount normal CD8 primary, secondary and memory responses to acute infection with lymphocytic choriomeningitis virus. Tetramer staining and cytotoxic experiments revealed a predominance of CD8-independent CTL in CD8beta KO mice. The TCR repertoire, especially the one of the TCRalpha chain, was different in CD8beta KO mice as compared with B6 mice. Our results indicate that in the absence of CD8beta, CD8-independent TCRs are preferentially selected, which in vivo effectively compensates for the reduced co-receptor function of CD8alphaalpha.

Coordination between zinc and phosphate homeostasis involves the transcription factor PHR1, the phosphate exporter PHO1, and its homologue PHO1;H3 in Arabidopsis.

Interactions between zinc (Zn) and phosphate (Pi) nutrition in plants have long been recognized, but little information is available on their molecular bases and biological significance. This work aimed at examining the effects of Zn deficiency on Pi accumulation in Arabidopsis thaliana and uncovering genes involved in the Zn-Pi synergy. Wild-type plants as well as mutants affected in Pi signalling and transport genes, namely the transcription factor PHR1, the E2-conjugase PHO2, and the Pi exporter PHO1, were examined. Zn deficiency caused an increase in shoot Pi content in the wild type as well as in the pho2 mutant, but not in the phr1 or pho1 mutants. This indicated that PHR1 and PHO1 participate in the coregulation of Zn and Pi homeostasis. Zn deprivation had a very limited effect on transcript levels of Pi-starvation-responsive genes such as AT4, IPS1, and microRNA399, or on of members of the high-affinity Pi transporter family PHT1. Interestingly, one of the PHO1 homologues, PHO1;H3, was upregulated in response to Zn deficiency. The expression pattern of PHO1 and PHO1;H3 were similar, both being expressed in cells of the root vascular cylinder and both localized to the Golgi when expressed transiently in tobacco cells. When grown in Zn-free medium, pho1;h3 mutant plants displayed higher Pi contents in the shoots than wild-type plants. This was, however, not observed in a pho1 pho1;h3 double mutant, suggesting that PHO1;H3 restricts root-to-shoot Pi transfer requiring PHO1 function for Pi homeostasis in response to Zn deficiency.

Brain Spectrins 240/235 and 240/235E: Differential Expression During Development of Chicken Dorsal Root Ganglia in vivo and in vitro.

Brain spectrin, a membrane-related cytoskeletal protein, exists as two isoforms. Brain spectrin 240/235 is localized preferentially in the perikaryon and axon of neuronal cells and brain spectrin 240/235E is found essentially in the neuronal soma and dendrites and in glia (Riederer et al., 1986, J. Cell Biol., 102, 2088 - 2097). The sensory neurons in dorsal root ganglia, devoid of any dendrites, make a good tool to investigate such differential expression of spectrin isoforms. In this study expression and localization of both brain spectrin isoforms were analysed during early chicken dorsal root ganglia development in vivo and in culture. Both isoforms appeared at embryonic day 6. Brain spectrin 240/235 exhibited a transient increase during embryonic development and was first expressed in ventrolateral neurons. In ganglion cells in situ and in culture this spectrin type showed a somato - axonal distribution pattern. In contrast, brain spectrin 240/235E slightly increased between E6 and E15 and remained practically unchanged. It was localized mainly in smaller neurons of the mediodorsal area as punctate staining in the cytoplasm, was restricted exclusively to the ganglion cell perikarya and was absent from axons both in situ and in culture. This study suggests that brain spectrin 240/235 may contribute towards outgrowth, elongation and maintenance of axonal processes and that brain spectrin 240/235E seems to be exclusively involved in the stabilization of the cytoarchitecture of cell bodies in a selected population of ganglion cells.

Avulsion fracture of the peroneus longus tendon insertion at the base of the first metatarsal: report of a case.

Isolated avulsion fracture of the peroneus longus tendon insertion at the base of the first metatarsal is very rare. Similar to most avulsion fractures that result from excessive strain at a tendon or ligament insertion, this type of injury is caused by the strong tension exerted by the peroneus longus tendon. The mechanisms leading to this lesion and treatment options are not clearly defined. We present the case of an isolated minimally displaced intra-articular avulsion fracture at the plantar lateral base of the first metatarsal. Faced with a painful non-union following conservative treatment we considered excision of the bony fragment and first tarsometatarsal arthrodesis. This leads to a favourable functional outcome.

Scoring system for renal pathology in Fabry disease: report of the international study group of fabry nephropathy (ISGFN).

BACKGROUND: In Fabry nephropathy, alpha-galactosidase deficiency leads to accumulation of glycosphingolipids in all kidney cell types, proteinuria and progressive loss of kidney function. METHODS: An international working group of nephrologists from 11 Fabry centres identified adult Fabry patients, and pathologists scored histologic changes on renal biopsies. A standardized scoring system was developed with a modified Delphi technique assessing 59 Fabry nephropathy cases. Each case was scored independently of clinical information by at least three pathologists with an average final score reported. RESULTS: We assessed 35 males (mean age 36.4 years) and 24 females (43.9 years) who mostly had clinically mild Fabry nephropathy. The average serum creatinine was 1.3 mg/dl (114.9 micromol/l); estimated glomerular filtration rate was 81.7 ml/min/1.73 m(2) and urine protein to creatinine ratio was 1.08 g/g (122.0 mg/mmol). Males had greater podocyte vacuolization on light microscopy (mean score) and glycosphingolipid inclusions on semi-thin sections than females. Males also had significantly more proximal tubule, peritubular capillary and vascular intimal inclusions. Arteriolar hyalinosis was similar, but females had significantly more arterial hyalinosis. Chronic kidney disease stage correlated with arterial and glomerular sclerosis scores. Significant changes, including segmental and global sclerosis, and interstitial fibrosis were seen even in patients with stage 1-2 chronic kidney disease with minimal proteinuria. CONCLUSIONS: The development of a standardized scoring system of both disease-specific lesions, i.e. lipid deposition related, and general lesions of progression, i.e. fibrosis and sclerosis, showed a spectrum of histologic appearances even in early clinical stage of Fabry nephropathy. These findings support the role of kidney biopsy in the baseline evaluation of Fabry nephropathy, even with mild clinical disease. The scoring system will be useful for longitudinal assessment of prognosis and responses to therapy for Fabry nephropathy.

Linking supply to demand: the neuronal monocarboxylate transporter MCT2 and the alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid receptor GluR2/3 subunit are associated in a common trafficking process.

MCT2 is the major neuronal monocarboxylate transporter (MCT) that allows the supply of alternative energy substrates such as lactate to neurons. Recent evidence obtained by electron microscopy has demonstrated that MCT2, like alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) receptors, is localized in dendritic spines of glutamatergic synapses. Using immunofluorescence, we show in this study that MCT2 colocalizes extensively with GluR2/3 subunits of AMPA receptors in neurons from various mouse brain regions as well as in cultured neurons. It also colocalizes with GluR2/3-interacting proteins, such as C-kinase-interacting protein 1, glutamate receptor-interacting protein 1 and clathrin adaptor protein. Coimmunoprecipitation of MCT2 with GluR2/3 and C-kinase-interacting protein 1 suggests their close interaction within spines. Parallel changes in the localization of both MCT2 and GluR2/3 subunits at and beneath the plasma membrane upon various stimulation paradigms were unraveled using an original immunocytochemical and transfection approach combined with three-dimensional image reconstruction. Cell culture incubation with AMPA or insulin triggered a marked intracellular accumulation of both MCT2 and GluR2/3, whereas both tumor necrosis factor alpha and glycine (with glutamate) increased their cell surface immunolabeling. Similar results were obtained using Western blots performed on membrane or cytoplasm-enriched cell fractions. Finally, an enhanced lactate flux into neurons was demonstrated after MCT2 translocation on the cell surface. These observations provide unequivocal evidence that MCT2 is linked to AMPA receptor GluR2/3 subunits and undergoes a similar translocation process in neurons upon activation. MCT2 emerges as a novel component of the synaptic machinery putatively linking neuroenergetics to synaptic transmission.

Molecular bases of circadian rhythmicity in renal physiology and pathology.

The physiological processes that maintain body homeostasis oscillate during the day. Diurnal changes characterize kidney functions, comprising regulation of hydro-electrolytic and acid-base balance, reabsorption of small solutes and hormone production. Renal physiology is characterized by 24-h periodicity and contributes to circadian variability of blood pressure levels, related as well to nychthemeral changes of sodium sensitivity, physical activity, vascular tone, autonomic function and neurotransmitter release from sympathetic innervations. The circadian rhythmicity of body physiology is driven by central and peripheral biological clockworks and entrained by the geophysical light/dark cycle. Chronodisruption, defined as the mismatch between environmental-social cues and physiological-behavioral patterns, causes internal desynchronization of periodic functions, leading to pathophysiological mechanisms underlying degenerative, immune related, metabolic and neoplastic diseases. In this review we will address the genetic, molecular and anatomical elements that hardwire circadian rhythmicity in renal physiology and subtend disarray of time-dependent changes in renal pathology.

The FoxO3a gene is a key negative target of canonical Notch signalling in the keratinocyte UVB response.

Notch signalling has an important role in skin homeostasis, promoting keratinocyte differentiation and suppressing tumorigenesis. Here we show that this pathway also has an essential anti-apoptotic function in the keratinocyte UVB response. Notch1 expression and activity are significantly induced, in a p53-dependent manner, by UVB exposure of primary keratinocytes as well as intact epidermis of both mouse and human origin. The apoptotic response to UVB is increased by deletion of the Notch1 gene or down-modulation of Notch signalling by pharmacological inhibition or genetic suppression of 'canonical' Notch/CSL/MAML1-dependent transcription. Conversely, Notch activation protects keratinocytes against apoptosis through a mechanism that is not linked to Notch-induced cell cycle withdrawal or NF-kappaB activation. Rather, transcription of FoxO3a, a key pro-apoptotic gene, is under direct negative control of Notch/HERP transcription in keratinocytes, and upregulation of this gene accounts for the increased susceptibility to UVB of cells with suppressed Notch signalling. Thus, the canonical Notch/HERP pathway functions as a protective anti-apoptotic mechanism in keratinocytes through negative control of FoxO3a expression.

Copy number variants, diseases and gene expression.

Copy number variation (CNV) has recently gained considerable interest as a source of genetic variation likely to play a role in phenotypic diversity and evolution. Much effort has been put into the identification and mapping of regions that vary in copy number among seemingly normal individuals in humans and a number of model organisms, using bioinformatics or hybridization-based methods. These have allowed uncovering associations between copy number changes and complex diseases in whole-genome association studies, as well as identify new genomic disorders. At the genome-wide scale, however, the functional impact of CNV remains poorly studied. Here we review the current catalogs of CNVs, their association with diseases and how they link genotype and phenotype. We describe initial evidence which revealed that genes in CNV regions are expressed at lower and more variable levels than genes mapping elsewhere, and also that CNV not only affects the expression of genes varying in copy number, but also have a global influence on the transcriptome. Further studies are warranted for complete cataloguing and fine mapping of CNVs, as well as to elucidate the different mechanisms by which they influence gene expression.

The V-ATPase proteolipid cylinder promotes the lipid-mixing stage of SNARE-dependent fusion of yeast vacuoles.

The V-ATPase V(0) sector associates with the peripheral V(1) sector to form a proton pump. V(0) alone has an additional function, facilitating membrane fusion in the endocytic and late exocytic pathways. V(0) contains a hexameric proteolipid cylinder, which might support fusion as proposed in proteinaceous pore models. To test this, we randomly mutagenized proteolipids. We recovered alleles that preserve proton translocation, normal SNARE activation and trans-SNARE pairing but that impair lipid and content mixing. Critical residues were found in all subunits of the proteolipid ring. They concentrate within the bilayer, close to the ring subunit interfaces. The fusion-impairing proteolipid substitutions stabilize the interaction of V(0) with V(1). Deletion of the vacuolar v-SNARE Nyv1 has the same effect, suggesting that both types of mutations similarly alter the conformation of V(0). Also covalent linkage of subunits in the proteolipid cylinder blocks vacuole fusion. We propose that a SNARE-dependent conformational change in V(0) proteolipids might stimulate fusion by creating a hydrophobic crevice that promotes lipid reorientation and formation of a lipidic fusion pore.

quantiNemo: an individual-based program to simulate quantitative traits with explicit genetic architecture in a dynamic metapopulation.

quantiNemo is an individual-based, genetically explicit stochastic simulation program. It was developed to investigate the effects of selection, mutation, recombination and drift on quantitative traits with varying architectures in structured populations connected by migration and located in a heterogeneous habitat. quantiNemo is highly flexible at various levels: population, selection, trait(s) architecture, genetic map for QTL and/or markers, environment, demography, mating system, etc. quantiNemo is coded in C++ using an object-oriented approach and runs on any computer platform. Availability: Executables for several platforms, user's manual, and source code are freely available under the GNU General Public License at http://www2.unil.ch/popgen/softwares/quantinemo.

Increased vulnerability to kainic acid-induced epileptic seizures in mice underexpressing the scaffold protein Islet-Brain 1/JIP-1.

Islet-Brain 1, also known as JNK-interacting protein-1 (IB1/JIP-1) is a scaffold protein mainly involved in the regulation of the pro-apoptotic signalling cascade mediated by c-Jun-N-terminal kinase (JNK). IB1/JIP-1 organizes JNK and upstream kinases in a complex that facilitates JNK activation. However, overexpression of IB1/JIP-1 in neurons in vitro has been reported to result in inhibition of JNK activation and protection against cellular stress and apoptosis. The occurrence and the functional significance of stress-induced modulations of IB1/JIP-1 levels in vivo are not known. We investigated the regulation of IB1/JIP-1 in mouse hippocampus after systemic administration of kainic acid (KA), in wild-type mice as well as in mice hemizygous for the gene MAPK8IP1, encoding for IB1/JIP-1. We show here that IB1/JIP-1 is upregulated transiently in the hippocampus of normal mice, reaching a peak 8 h after seizure induction. Heterozygous mutant mice underexpressing IB1/JIP-1 showed a higher vulnerability to the epileptogenic properties of KA, whereas hippocampal IB1/JIP-1 levels remained unchanged after seizure induction. Subsequently, an increasing activation of JNK in the 8 h following seizure induction was observed in IB1/JIP-1 haploinsufficient mice, which also underwent more severe excitotoxic lesions in hippocampal CA3, as assessed histologically 3 days after KA administration. Taken together, these data indicate that IB1/JIP-1 in hippocampus participates in the regulation of the neuronal response to excitotoxic stress in a level-dependent fashion.

Pharmacokinetic parameters of artesunate and dihydroartemisinin in rats infected with Fasciola hepatica

OBJECTIVES: The pharmacokinetic (PK) parameters of artesunate, recently discovered to possess promising trematocidal activity, and its main metabolite dihydroartemisinin (DHA) were determined in rats infected with hepatic and biliary stages of Fasciola hepatica and compared with uninfected rats after single intragastric and intravenous (iv) doses. METHODS: Rats infected with F. hepatica for 25 and 83 days and uninfected rats were cannulated in the right jugular vein and blood samples were withdrawn at selected timepoints following 10 mg/kg of iv and a single 100 mg/kg oral dose of artesunate. Plasma was analysed for artesunate and DHA by liquid chromatography coupled to tandem mass spectrometry. RESULTS: Rats harbouring juvenile and adult F. hepatica infections revealed considerable changes in PK parameters of artesunate and DHA. Following oral administration, maximum plasma concentrations (C(max)) of artesunate and DHA were 1.8-2.3-fold higher in infected rats [artesunate: 1334 +/- 1404 ng/mL (no infection) versus 2454 +/- 1494 ng/mL (acute infection) and 2768 +/- 538 ng/mL (chronic infection); DHA: 3802 +/- 2149 ng/mL (no infection) versus 6507 +/- 3283 ng/mL (acute infection) and 9093 +/- 884 ng/mL (chronic infection)]. The AUCs of artesunate and DHA were 2.1-4.4-fold greater in infected rats. An opposite trend was observed after iv injection. C(max) and AUC of artesunate and DHA following iv dosing were 5784 +/- 3718 and 140 938 +/- 128 783 ng.min/mL and 3849 +/- 3060 and 86 107 +/- 41 863 ng.min/mL, respectively, in uninfected rats versus 2623 +/- 1554 and 21 617 +/- 12 230 ng.min/mL and 2835 +/- 980 and 64 290 +/- 29 057 ng.min/mL, respectively, in rats harbouring a chronic infection. The elimination half-lives (t(1/2)) of artesunate and DHA were considerably altered in infected rats following oral and iv administration of artesunate. CONCLUSIONS: F. hepatica infections strongly influence the disposition kinetics of artesunate and its metabolite in rats. The clinical implications of this finding need to be carefully studied.