Aims/hypothesis
Maternal low-protein (LP) diet during gestation results in a reduced beta cell mass in the offspring at birth and this may hamper the ability to adapt to high-energy food and ...sedentary lifestyle later in life. To investigate the biology behind the LP-offspring phenotype, this study aimed to identify differentially expressed genes in the pancreas and their potential role in the fetal programming.
Methods
Wistar rats were given either an LP diet or normal-chow (NC) diet during gestation and differentially expressed genes in the offspring around the time of birth were identified using RNA microarray and quantitative PCR. The role of a differentially expressed gene, growth arrest specific protein 6 (GAS6), was evaluated in vitro using neonatal rat islets.
Results
The mRNA level of
Gas6
, known to be mitogenic in other tissues, was reduced in LP offspring. The mRNA content of
Mafa
was increased in LP offspring suggesting an early maturation of beta cells. When applied in vitro, GAS6 increased proliferation of neonatal pancreatic beta cells, while reducing glucose-stimulated insulin secretion without changing the total insulin content of the islets. In addition, GAS6 decreased the mRNA content of
Mafa
.
Conclusions/interpretation
We propose a role for GAS6 in the regulation of pancreatic beta cells in the critical period around the time of birth. Our results support the hypothesis that the reduced beta cell mass seen in LP offspring is caused by a change in the intra-uterine environment that favours premature maturation of the beta cells.
This paper presents the characterization of total ionizing dose (TID) effects on an highly-integrated radio frequency (RF) agile transceiver to ultra-high dose levels. The DUT shows no RF-specific ...degradation up to 40 Mrad(SiO 2 ). Malfunctions on the digital interfaces are assessed at ~45 Mrad(SiO 2 ) which results into a non-functional operation of the DUT. Additional TID testing to 80 Mrad(SiO 2 ) has been performed to investigate further behavior. Rebound effects during 100°C tempered post-test annealing to almost nominal operations are observed.
Detailed clinical, neuroradiological, histological, biochemical, and genetic investigations were undertaken in a child suffering from Leigh syndrome. The clinical symptoms started at age five months ...and led to a severe progressive neurodegenerative disorder causing epilepsy, psychomotor retardation, and tetraspasticity. Biochemical measurement of skeletal muscle showed a severe decrease in mitochondrial complex II. Sequencing of SDHA revealed compound heterozygosity for a nonsense mutation in exon 4 (W119X) and a missense mutation in exon 3 (A83V), both absent in normal controls. In six additional patients—five with Leigh or Leigh-like syndrome and one with neuropathy and ataxia associated with isolated deficiency of complex II—mutations in SDHA were not detected, indicating genetic heterogeneity.
Background: Liver diseases include a wide spectrum of both acute and chronic conditions which are associated with significant morbidity and mortality worldwide. Hepatocyte transplantation has ...therapeutic potential in the treatment of liver diseases, but its clinical use is hampered by the lack of donor tissue. Generation of hepatocytes in vitro from adult or fetal liver cell progenitors or, alternatively, identification of a progenitor population which in vivo can generate mature liver cells could solve this problem. Methods: CD117+/CD34+/Lin− human fetal liver cells were isolated by magnetic cell sorting and expanded in culture. Both freshly isolated and in vitro expanded cells in various passages were studied for their ability to be functional in hepatic parenchyma following d-galactosamine (GalN) induced injury in nude C57 black mice. Results: Freshly isolated and in vitro expanded CD117+/CD34+/Lin− cells, when transplanted intrasplenically into GalN treated mice, morphologically and functionally differentiated into hepatocytes and cholangiocytes. Human specific albumin, α fetoprotein, cytokeratin 19, and antitrypsin mRNA were expressed in mouse liver. In addition, the human progenitor cells expressed glucose-6-phosphatase, glycogen, albumin, gamma glutamyl transpeptidase, and dipeptidyl peptidase IV after transplantation. Expanded cells in various passages maintained their capacity to differentiate into functional liver cells. Conclusions: Fetal liver CD117+/CD34+/Lin− progenitors and their progeny proliferated in vitro and also functionally differentiated into mature hepatic cells in an acute liver injury model. Successful in vitro expansion of liver progenitor cells provides a basis for developing cell therapy strategies, metabolic and toxicity testing systems, and may serve as a vehicle for gene therapy.
Despite improvements in allogeneic stem cell transplantation, acute graft‐versus‐host disease (GVHD) remains a significant problem after transplantation, and it is still a major cause of ...post‐transplant mortality. Disease progression is characterized by the differentiation of alloreactive T cells to effector cells leading to tissue damage, recruitment of additional inflammatory cell populations and further cytokine dysregulation. To make the complex process of acute GVHD more explicit, the pathophysiology of acute GVHD is often divided into three different phases. This review summarizes the mechanisms involved in the three phases of acute GVHD.
Mutations in SCO2, a cytochrome c oxidase (COX) assembly gene located on chromosome 22, have recently been reported in patients with fatal infantile cardio-encephalomyopathy and severe COX deficiency ...in heart and skeletal muscle. The Sco2 protein is thought to function as a copper chaperone. To investigate the extent to which mutations in SCO2 are responsible for this phenotype, a complete sequence analysis of the gene was performed on ten patients in nine families. Mutations in SCO2 were found in three patients in two unrelated families. We detected two missense mutations, one of which (G1541A) results in an E140K substitution adjacent to the highly conserved CxxxC metal-binding site. The other (C1634T) results in an R171W substitution more distant from the copper-binding site. A nonsense codon was found on one allele in two siblings presenting with a rapidly progressive fatal cardio-encephalomyopathy. Interestingly, all patients so far reported are compound heterozygotes for the G1541A mutation, suggesting that this is either an ancient allele or a mutational hotspot. The COX deficiency in patient fibroblasts (approximately 50%) did not result in a measurable decrease in the steady-state levels of COX complex polypeptide subunits and could be rescued by transferring chromosome 22, but not other chromosomes. These data indicate that mutations in SCO2 cause a fatal infantile mitochondrial disorder characterized by hypertrophic cardiomyopathy and encephalopathy, and point to the presence of one or more other genes, perhaps in the copper delivery pathway, in this clinical phenotype.
We report on clinical, histological and genetic findings in two patients carrying novel heteroplasmic mutations in the mitochondrial cytochrome
c oxidase subunit genes
COII and
COIII. The first ...patient, a 35 year-old man had a multisystemic disease, with clinical symptoms of bilateral cataract, sensori-neural hearing loss, myopathy, ataxia, cardiac arrhythmia, depression and short stature and carried a 7970 G>T (E129X) nonsense mutation in
COII. A sudden episode of metabolic encephalopathy caused by extremely high blood lactate lead to coma. The second patient developed exercise intolerance and rhabdomyolysis at age 22 years. A heteroplasmic missense mutation 9789 T>C (S195P) was found in skeletal muscle, but not in blood and myoblasts pointing to a sporadic mutation. Our report of two patients with isolated COX deficiency and new mutations in COX subunit genes may help to draw more attention to this type of mtDNA defects and provide new aspects for counselling affected families.
Mutations in Sco2, a protein involved in copper trafficking to the terminal enzyme of the respiratory chain, cytochrome c oxidase, results in infantile hypertrophic cardioencephalomyopathy. We have ...recently shown that copper‐histidine (Cu‐his) supplementation of Sco2‐deficient myoblasts rescues COX activity in vitro. Here, we report a patient with SCO2 mutations and with resolution of severe hypertrophic cardiomyopathy. Weighing up the evidence, the most likely explanation for the improved cardiac function in this patient was the subcutaneous application of Cu‐his.
Mutations in SCO2, a cytochrome c oxidase (COX) assembly gene, have been reported in nine infants with early onset fatal cardioencephalomyopathy and a severe COX deficiency in striated muscle. ...Studies on a yeast homolog have suggested that human Sco2 acts as a copper chaperone, transporting copper to the Cu(A) site on the Cox II subunit, but the mechanism of action remains unclear. To investigate the molecular basis of pathogenesis of Sco2 defects in humans we performed genetic and biochemical studies on tissues, myoblasts and fibroblasts from affected patients, as well as on a recombinant human C-terminal Sco2 segment (22 kDa), bearing the putative CxxxC metal-binding motif. Recombinant Sco2 was shown to bind copper with a 1:1 stoichiometry and to form homomeric complexes in vitro, independent of the metal-binding motif. Immunohistochemistry using antibodies directed against different COX subunits showed a marked tissue-specific decrease in the Cox II/III subunits that form part of the catalytic core, consistent with the differential tissue involvement, but a more uniform distribution of Cox Vab, a nuclear-encoded subunit. Sco2 was severely reduced in patient fibroblasts and myoblasts by immunoblot analysis. Patient fibroblasts showed increased (64)Cu uptake but normal retention values and, consistent with this, the copper concentration was four times higher in Sco2-deficient myoblasts than in controls. COX activity in patient myoblasts was completely rescued by transduction with a retroviral vector expressing the human SCO2 coding sequence, and more interestingly by addition of copper-histidine (300 microM) to the culture medium. Whether the latter is accomplished by the very low residual levels of Sco2 in the patient cells, direct addition of copper to the Cu(A) site, or by another copper-binding protein remains unknown. Whatever the mechanism, this result suggests a possible therapy for the early treatment of this fatal infantile disease.
Mitochondrial (mt)DNA haplogroups in a German control group (n = 67) were characterized by screening mitochondrial coding regions encompassing most of the ND, tRNA and cyt b genes. We used a PCR-SSCP ...screening approach followed by direct sequencing of polymorphic mtDNA fragments. Five major mtDNA lineages, diverging in at least nine different haplogroups, could be defined by characteristic polymorphic sites in mitochondrial genes. Additional sequencing of two hypervariable segments (HVS-I and II) of the non-coding displacement (D) loop in all control subjects revealed that certain D loop variants were strongly correlated with lineages and haplogroups, while others represented hotspots occurring frequently in different haplogroups. The existence of identified lineages and haplogroups received support from data in the literature, obtained by use of different approaches. Subsequently, we investigated four disease groups for association with these haplogroups: (i) LHON patients (n = 55) carrying at least one of the primary/intermediate LHON mutations at nt 3460, 11778, 14484 and/or 15257; (ii) patients suffering from Wolfram or DIDMOAD syndrome(n = 8); (iii) MELAS patients (n = 9); (iv) a group of children, who died from ‘sudden infant death syndrome’ (SIDS) (n = 9). The distribution patterns among the haplogroups of the disease groups (LHON, DIDMOAD and SIDS) differed considerably from the control population. LHON and DIDMOAD were significantly under-represented in the most frequent German haplogroup DC, but were concentrated in a mtDNA lineage defined by polymorphisms at nt 4216+11251+16126. As this lineage diverged into two precisely defined haplogroups, LHON and DIDMOAD could be assigned to the two haplogroups separately. Strikingly, SIDS was often found in association with two rare German haplogroups. MELAS patients were equally distributed among German haplogroups and, moreover, did not reveal any accumulation of specific D loop variants. We conclude that certain European mtDNA haplogroups define a genetic susceptibility basis for various disorders.
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