Long-term treated HIV infection is associated with platelet mitochondrial dysfunction.

HIV infection and antiretroviral therapy have been linked to mitochondrial dysfunction. The role of platelet mitochondrial dysfunction in thrombosis, immunoregulation and age-related diseases is increasingly appreciated. Here, we studied platelet mitochondrial DNA content (mtDNApl) and mitochondrial function in people living with HIV (PLHIV) and related this to platelet function. In a cohort of 208 treated PLHIV and 56 uninfected controls, mtDNApl was quantified, as well as platelet activation, platelet agonist-induced reactivity and inflammation by circulating factors and flow cytometry. In a subgroup of participants, the metabolic activity of platelets was further studied by mitochondrial function tests and the Seahorse Flux Analyzer. PLHIV had significantly lower mtDNApl compared to controls (8.5 copies/platelet (IQR: 7.0-10.7) vs. 12.2 copies/platelet (IQR: 9.5-16.6); p < 0.001), also after correction for age, sex and BMI. Prior zidovudine-use (n = 46) was associated with a trend for lower mtDNApl. PLHIV also had reduced ex vivo platelet reactivity and mean platelet volume compared to controls. MtDNApl correlated positively with both platelet parameters and correlated negatively with inflammatory marker sCD163. Mitochondrial function tests in a subgroup of participants confirmed the presence of platelet mitochondrial respiration defects. Platelet mitochondrial function is disturbed in PLHIV, which may contribute to platelet dysfunction and subsequent complications. Interventions targeting the preservation of normal platelet mitochondrial function may ultimately prove beneficial for PLHIV.

Diverse phenotype in patients with complex I deficiency due to mutations in NDUFB11.

Mitochondrial complex I deficiency is the most frequent mitochondrial disorder presenting in childhood and the mutational spectrum is highly heterogeneous. The NDUFB11 gene is one of the recently identified genes, which is located in the short arm of the X-chromosome. Here we report clinical, biochemical, functional and genetic findings of two male patients with lactic acidosis, hypertrophic cardiomyopathy and isolated complex I deficiency due to de novo hemizygous mutations (c.286C > T and c.328C > T) in the NDUFB11 gene. Neither of them had any skin manifestations. The NDUFB11 gene encodes a relatively small integral membrane protein NDUFB11, which is essential for the assembly of an active complex I. The expression levels of this protein was decreased in both patient cells and a lentiviral complementation experiment also supported the notion that the complex I deficiency in those two patients is caused by NDUFB11 genetic defects. Our findings together with a review of the thirteen previously described patients demonstrate a wide spectrum of clinical features associated with NDUFB11-related complex I deficiency. However, histiocytoid cardiomyopathy and/or congenital sideroblastic anemia could be indicative for mutation in the NDUFB11 gene, while the clinical manifestation of the same mutation can be highly variable.

NDUFAF4 variants are associated with Leigh syndrome and cause a specific mitochondrial complex I assembly defect.

Mitochondrial respiratory chain complex I consists of 44 different subunits and can be subgrouped into three functional modules: the Q-, the P- and the N-module. NDUFAF4 (C6ORF66) is an assembly factor of complex I that associates with assembly intermediates of the Q-module. Via exome sequencing, we identified a homozygous missense variant in a complex I-deficient patient with Leigh syndrome. Supercomplex analysis in patient fibroblasts revealed specifically altered stoichiometry. Detailed assembly analysis of complex I, indicative of all of its assembly routes, showed an accumulation of parts of the P- and the N-module but not the Q-module. Lentiviral complementation of patient fibroblasts with wild-type NDUFAF4 rescued complex I deficiency and the assembly defect, confirming the causal role of the variant. Our report on the second family affected by an NDUFAF4 variant further characterizes the phenotypic spectrum and sheds light into the role of NDUFAF4 in mitochondrial complex I biogenesis.

A novel mutation in FBXL4 in a Norwegian child with encephalomyopathic mitochondrial DNA depletion syndrome 13.

Mitochondrial DNA depletion syndromes (MTDPS) represent a clinically and genetically heterogeneous group of autosomal recessive disorders, caused by mutations in genes involved in maintenance of mitochondrial DNA (mtDNA). Biallelic mutations in FBXL4 were recently described to cause encephalomyopathic MTDPS13. The syndrome has infantile onset and presents with hypotonia, feeding difficulties, a pattern of mild facial dysmorphisms, global developmental delay and brain atrophy. Laboratory investigations reveal elevated blood lactate levels, unspecific mitochondrial respiratory chain (MRC) enzyme deficiencies and mtDNA depletion. We report a novel missense variant, c.1442T > C (p.Leu481Pro), in FBXL4 (NM_012160.4) in a Norwegian boy with clinical, biochemical and cerebral MRI characteristics consistent with MTDPS13. The FBXL4 c.1442T > C (p.Leu481Pro) variant was not present in public databases, 149 Norwegian controls nor an in-house database containing whole exome sequencing data from 440 individuals, and it was predicted in silico to be deleterious to the protein function. Activities of MRC enzymes were normal in muscle tissue (complexes I-IV) and cultured skin fibroblasts (complexes I-V) from the patient, but mtDNA depletion was confirmed in muscle, thus supporting the predicted pathogenicity of the FBXL4 c.1442T > C (p.Leu481Pro) variant. On clinical indication of mitochondrial encephalomyopathy, sequencing of FBXL4 should be performed, even when the activity levels of the MRC enzymes are normal.

Attitude toward contraception and abortion among Curaçao women. Ineffective contraception due to limited sexual education?

BACKGROUND: In Curaçao is a high incidence of unintended pregnancies and induced abortions. Most of the induced abortions in Curaçao are on request of the woman and performed by general practitioners. In Curaçao, induced abortion is strictly prohibited, but since 1999 there has been a policy of connivance. We present data on the relevance of economic and socio-cultural factors for the high abortion-rates and the ineffective use of contraception. METHODS: Structured interviews to investigate knowledge and attitudes toward sexuality, contraception and abortion and reasons for ineffective use of contraceptives among women, visiting general practitioners. RESULTS: Of 158 women, 146 (92%) participated and 82% reported that their education on sexuality and about contraception was of good quality. However 'knowledge of reliable contraceptive methods' appeared to be--in almost 50% of the cases--false information, misjudgements or erroneous views on the chance of getting pregnant using coitus interruptus and about the reliability and health effects of oral contraceptive pills. Almost half of the interviewed women had incorrect or no knowledge about reliability of condom use and IUD. 42% of the respondents risked by their behavior an unplanned pregnancy. Most respondents considered abortion as an emergency procedure, not as contraception. Almost two third experienced emotional, physical or social problems after the abortion. CONCLUSIONS: Respondents had a negative attitude toward reliable contraceptives due to socio-cultural determined ideas about health consequences and limited sexual education. Main economic factors were costs of contraceptive methods, because most health insurances in Curaçao do not cover contraceptives. To improve the effective use of reliable contraceptives, more adequate information should be given, targeting the wrong beliefs and false information. The government should encourage health insurance companies to reimburse contraceptives. Furthermore, improvement of counseling during the abortion procedure is important.

Mutation in mitochondrial ribosomal protein MRPS22 leads to Cornelia de Lange-like phenotype, brain abnormalities and hypertrophic cardiomyopathy.

The oxidative phosphorylation (OXPHOS) system is under control of both the mitochondrial and the nuclear genomes; 13 subunits are synthesized by the mitochondrial translation machinery. We report a patient with Cornelia de Lange-like dysmorphic features, brain abnormalities and hypertrophic cardiomyopathy, and studied the genetic defect responsible for the combined OXPHOS complex I, III and IV deficiency observed in fibroblasts. The combination of deficiencies suggested a primary defect associated with the synthesis of mitochondrially encoded OXPHOS subunits. Analysis of mitochondrial protein synthesis revealed a marked impairment in mitochondrial translation. Homozygosity mapping and sequence analysis of candidate genes revealed a homozygous mutation in MRPS22, a gene encoding a mitochondrial ribosomal small subunit protein. The mutation predicts a Leu215Pro substitution at an evolutionary conserved site. Mutations in genes implicated in Cornelia de Lange syndrome or copy number variations were not found. Transfection of patient fibroblasts, in which MRPS22 was undetectable, with the wild-type MRPS22 cDNA restored the amount and activity of OXPHOS complex IV, as well as the 12S rRNA transcript level to normal values. These findings demonstrate the pathogenicity of the MRPS22 mutation and stress the significance of mutations in nuclear genes, including genes that have no counterparts in lower species like bacteria and yeast, for mitochondrial translation defects.

PHYLOGENETIC POSITION OF ATTHEYA LONGICORNIS AND ATTHEYA SEPTENTRIONALIS (BACILLARIOPHYTA)(1).

The phylogenetic position of diatoms belonging to the genus Attheya is presently under debate. Species belonging to this genus have been placed in the subclasses Chaetocerotophycidae and Biddulphiophycidae, but published phylogenetic trees based on 18S rDNA, morphology, and sexual reproduction indicate that this group of diatoms may be a sister group of the pennates. To clarify the position of Attheya, we studied the morphology, 18S rDNA, 16S rDNA of the chloroplasts, the rbcL large subunit (LSU) sequences of the chloroplasts, and the sterol composition of three different strains of Attheya septentrionalis (Østrup) R. M. Crawford and one strain of Attheya longicornis R. M. Crawford et C. Gardner. These data were compared with data from more than 100 other diatom species, covering the whole phylogenetic tree, with special emphasis on species belonging to the genera that have been suggested to be related to the genus Attheya. All data suggest that the investigated Attheya species form a separate group of diatoms, and there is no indication that they belong to either the Chaetocerotophycidae or the Biddulphiophycidae. Despite applying these various approaches, we were unable to determine the exact phylogenetic position of the investigated Attheya species within the diatoms.

Major gradients in putatively nitrifying and non-nitrifying Archaea in the deep North Atlantic.

Aerobic nitrification of ammonia to nitrite and nitrate is a key process in the oceanic nitrogen cycling mediated by prokaryotes. Apart from Bacteria belonging to the beta- and gamma-Proteobacteria involved in the first nitrification step, Crenarchaeota have recently been recognized as main drivers of the oxidation of ammonia to nitrite in soil as well as in the ocean, as indicated by the dominance of archaeal ammonia monooxygenase (amoA) genes over bacterial amoA. Evidence is accumulating that archaeal amoA genes are common in a wide range of marine systems. Essentially, all these reports focused on surface and mesopelagic (200-1,000 m depth) waters, where ammonia concentrations are higher than in waters below 1,000 m depth. However, Crenarchaeota are also abundant in the water column below 1,000 m, where ammonia concentrations are extremely low. Here we show that, throughout the North Atlantic Ocean, the abundance of archaeal amoA genes decreases markedly from subsurface waters to 4,000 m depth, and from subpolar to equatorial deep waters, leading to pronounced vertical and latitudinal gradients in the ratio of archaeal amoA to crenarchaeal 16S ribosomal RNA (rRNA) genes. The lack of significant copy numbers of amoA genes and the very low fixation rates of dark carbon dioxide in the bathypelagic North Atlantic suggest that most bathypelagic Crenarchaeota are not autotrophic ammonia oxidizers: most likely, they utilize organic matter and hence live heterotrophically.