Met gezonde bijen naar de heide

Op 22 maart 2010 kwam een bont gezelschap van bijenhouders van ABTB, ANI en NBV bijeen in Hoenderloo. Het onderwerp die avond was de vraag: “Hoe combineer ik varroabestrijding met de heidedracht?” Hieronder het antwoord en wel in de vorm van de basisprincipes van varroa bestrijding plus een concrete methode om deze te combineren met de heidedracht

Tumour necrosis factor alpha, lipid peroxidation and NO* are increased and associated with decreased free-radical scavenging enzymes in patients with Weill-Marchesani syndrome.

AIM: Weill-Marchesani syndrome (WMS) is a rare systemic disorder with both autosomal recessive and dominant inheritances. Accumulation of reactive oxygen species such as O2*-, H2O2 and OH* causes lipid peroxidation (LPO), whereas antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSHPx)) mediate defence against oxidative stress. Excess tumour necrosis factor (TNF)-alpha and NO* react with O2*- and cause further antioxidant depletion with an increase in mutation frequency by H2O2. This study investigated the levels of SOD, GSHPx, catalase (CAT), TNF-alpha, NO and LPO in patients with WMS. METHODS: A group of 10 WMS patients (four males, six females; age, 26.5+/-19.0 years) and 10 age-matched and sex-matched controls (five males, five females; age, 27.3+/-18.2 years) were included. Serum TNF-alpha levels were determined by a spectrophotometer technique using immulite chemiluminescent immunometric assay. Malondialdehyde (MDA) was determined in plasma; CAT in red blood cells (RBCs), and SOD and GSHPx in both plasma and RBCs. Total serum NO* levels were evaluated by Griess reaction. RESULTS: Mean levels of TNF-alpha (8.3+/-0.6 pg/ml) in WMS patients were significantly (p<0.001) higher than controls (4.3+/-0.2 pg/ml). Plasma MDA levels in patients and controls were 5.4+/-0.8 and 1.8+/-0.6 micromol/l, respectively, and the difference was significant (p=0.0002). SOD and GSHPx activities were significantly lower in both RBCs and plasma of WMS than in controls (RBC-SOD, 3981.9+/-626.6 versus 5261.6+/-523.0 U/g haemoglobin (Hb), p=0.0005; plasma-SOD, 529.4+/-49.3 versus 713.4+/-55.7 U/g protein, p=0.0002; RBC-GSHPx, 682.7+/-42.0 versus 756.5+/-47.6 U/g Hb, p=0.0011; plasma-GSHPx, 107.3+/-15.0 versus 131.4+/-19.7 U/g protein, p=0.0113). In addition, serum NO (NO*-2 + NO*-3) levels were also significantly (p = 0.0002) increased in WMS patients (54.4+/-5.7 versus 26.9+/-6.7 micromol/l). RBC-CAT levels were similar between groups (125.6+/-21.3 versus 131.0+/-21.5 k/g Hb, p = 0.8798). CONCLUSIONS: The elevated LPO, TNF-alpha and NO* with decreased antioxidant enzyme activities indicated impaired antioxidative defence mechanisms with an oxidative injury and cell toxicity in WMS patients. The use of multiple antioxidants and free radical scavengers might be helpful in this genetic disorder

New cut-off values for ferritin and soluble transferrin receptor for the assessment of iron deficiency in children in a high infection pressure area

Background: Due to the potential risk of iron supplementation in iron replete children, it is important to properly identify children who may require iron supplementation. However, assessment of the iron status has proven to be difficult, especially in children living in areas with high infection pressure (including malaria). Aims and Methods: Biochemical iron markers were compared to bone marrow iron findings in 381 Malawian children with severe anaemia. Results: Soluble transferrin receptor/log ferritin (TfR-F index), using a cut-off of 5.6, best predicted bone marrow iron stores deficiency (sensitivity 74%, specificity 73%, accuracy 73%). In order to improve the diagnostic accuracy of ferritin or sTfR as a stand-alone marker, the normal cut-off value needed to be increased by 810% and 83% respectively. Mean cell haemoglobin concentration (MCHC), using a cut-off of 32.1 g/dl, had a sensitivity of 67% and specificity of 64% for detecting iron stores deficiency. Conclusion: TfR-F index incorporated the high sensitivity of sTfR, a proxy for cellular iron need, and the high specificity of ferritin, a proxy for iron stores. In areas with a high infection pressure, the TfR-F index best predicted iron deficiency. However, in settings where diagnostic tests are limited, MCHC may be an acceptable alternative screening test

Improved method for assessing iron stores in the bone marrow

Background: Bone marrow iron microscopy has been the "gold standard'' method of assessing iron deficiency. However, the commonly used method of grading marrow iron remains highly subjective. Aim: To improve the bone marrow grading method by developing a detailed protocol that assesses iron in fragments, in macrophages around fragments and in erythroblasts. Methods: A descriptive study of marrow aspirates of 303 children (aged 6-60 months) with severe anaemia and 22 controls (children undergoing elective surgery) was conducted at hospitals in southern Malawi (2002-04). Results: Using an intensive marrow iron grading method, 22% and 39% of cases and controls had deficient iron stores, and 40% and 46% had functional iron deficiency, respectively. Further evaluation of the iron status classification by the intensive method showed that functional iron deficiency was associated with significantly increased C-reactive protein concentrations (126.7 (85.6) mg/l), and iron stores deficiency with significantly increased soluble transferrin receptor concentrations (21.7 (12.5) mg/ml). Conclusions: Iron assessment can be greatly improved by a more intense marrow examination. This provides a useful iron status classification which is of particular importance in areas where there is a high rate of inflammatory conditions

Defective complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome

Background: Leigh syndrome is an early onset, progressive, neurodegenerative disorder with developmental and motor skills regression. Characteristic magnetic resonance imaging abnormalities consist of focal bilateral lesions in the basal ganglia and/or the brainstem. The main cause is a deficiency in oxidative phosphorylation due to mutations in an mtDNA or nuclear oxidative phosphorylation gene. Methods and results: A consanguineous Moroccan family with Leigh syndrome comprise 11 children, three of which are affected. Marker analysis revealed a homozygous region of 11.5 Mb on chromosome 20, containing 111 genes. Eight possible mitochondrial candidate genes were sequenced. Patients were homozygous for an unclassified variant (p.P193L) in the cardiolipin synthase gene (CRLS1). As this variant was present in 20% of a Moroccan control population and enzyme activity was only reduced to 50%, this could not explain the rare clinical phenotype in our family. Patients were also homozygous for an amino acid substitution (p.L159F) in C20orf7, a new complex I assembly factor. Parents were heterozygous and unaffected sibs heterozygous or homozygous wild type. The mutation affects the predicted S-adenosylmethionine (SAM) dependent methyltransferase domain of C20orf7, possibly involved in methylation of NDUFB3 during the assembly process. Blue native gel electrophoresis showed an altered complex I assembly with only 30-40% of mature complex I present in patients and 70-90% in carriers. Conclusions: A new cause of Leigh syndrome can be a defect in early complex I assembly due to C20orf7 mutations

Degenerate T-cell Recognition of Peptides on MHC Molecules Creates Large Holes in the T-cell Repertoire

The cellular immune system screens peptides presented by host cells on MHC molecules to assess if the cells are infected. In this study we examined whether the presented peptides contain enough information for a proper self/nonself assessment by comparing the presented human (self) and bacterial or viral (nonself) peptides on a large number of MHC molecules. For all MHC molecules tested, only a small fraction of the presented nonself peptides from 174 species of bacteria and 1000 viral proteomes (0.2%) is shown to be identical to a presented self peptide. Next, we use available data on T-cell receptor-peptide-MHC interactions to estimate how well T-cells distinguish between similar peptides. The recognition of a peptide-MHC by the T-cell receptor is flexible, and as a result, about one-third of the presented nonself peptides is expected to be indistinguishable (by T-cells) from presented self peptides. This suggests that T-cells are expected to remain tolerant for a large fraction of the presented nonself peptides, which provides an explanation for the “holes in the T-cell repertoire” that are found for a large fraction of foreign epitopes. Additionally, this overlap with self increases the need for efficient self tolerance, as many self-similar nonself peptides could initiate an autoimmune response. Degenerate recognition of peptide-MHC-I complexes by T-cells thus creates large and potentially dangerous overlaps between self and nonself

Wastage amidst shortage: Strategies for the mitigation of standby electricity in residential sector in Nigeria

Abstract : Due to rising population and the increasing rate of urbanization, residential electricity usage accounts for a large chunk of Nigeria’s electricity consumption. However, little attention is paid to electricity conservation in the country. In response to this, several studies are been tailored to ensure a rapid reduction in energy consumption through various alternatives including energy efficient technologies given the current state of inadequate electricity supply in the country. On this note, this article discusses the significance of standby electricity in Nigeria. The electricity generation and consumption patterns were briefly discussed while the current electricity saving behaviour and practices among the urban dwellers were detailed with a case study analysed. Based on the case study, it was discovered that the mean standby load across the 30 households were estimated at 60 W ranging from 34-144 W. Also, standby consumption accounts for 13-44% of the annual electricity consumption across the households. Finally, the strategies for electricity saving and sustainable consumption, most especially the mitigation of standby electricity were highlighted

De Novo Transcriptome Assembly and Comparative Analysis Elucidate Complicated Mechanism Regulating Astragalus chrysochlorus Response to Selenium Stimuli

Astragalus species are medicinal plants that are used in the world for years. Some Astragalus species are known for selenium accumulation and tolerance and one of them is Astragalus chrysochlorus, a secondary selenium accumulator. In this study, we employed Illumina deep sequencing technology for the first time to de novo assemble A. chrysochlorus transcriptome and identify the differentially expressed genes after selenate treatment. Totally, 59,656 unigenes were annotated with different databases and 53,960 unigenes were detected in NR database. Transcriptome in A. chrysochlorus is closer to Glycine max than other plant species with 43,1 percentage of similarity. Annotated unigenes were also used for gene ontology enrichment and pathway enrichment analysis. The most significant genes and pathways were ABC transporters, plant pathogen interaction, biosynthesis of secondary metabolites and carbohydrate metabolism. Our results will help to enlighten the selenium accumulation and tolerance mechanisms, respectively in plants