The reliability of the All-Up concept Special technical report no. 13

Implementation approaches for conducting Saturn V launch vehicle program without dummy stage

Effects of pre- and postnatal exposure to chlorinated dioxins and furans on human neonatal thyroid hormone concentrations.

Animal studies have shown that dioxins influence plasma thyroid hormone concentrations. To investigate the effect of chlorinated dioxins and furans on thyroid hormone concentrations in humans, we studied 38 healthy breast-fed infants. The study population was divided into two groups according to the dioxin concentrations in milk fat of their mothers. Blood samples were taken at birth and at the ages of 1 and 11 weeks. At birth a tendency to higher total thyroxine (tT4) concentrations was found in the high exposure group. At the ages of 1 and 11 weeks the increase of mean tT4 concentrations and tT4/thyroxine-binding globulin ratios in the high exposure group reached significance as compared to the low exposure group. At birth and 1 week after birth, mean thyrotropin (TSH) concentrations were similar in both groups, but at the age of 11 weeks the mean TSH concentrations were significantly higher in the high exposure group. We postulate that the observed plasma tT4 elevation in infants exposed to dioxins before and after birth is the result of an effect on the thyroid hormone regulatory system

Appraisals and coping mediate the relationship between resilience and distress among significant others of persons with spinal cord injury or acquired brain injury: A cross-sectional study

Background: Many significant others of persons with serious conditions like spinal cord injury (SCI) and acquired brain injury (ABI) report high levels of psychological distress. In line with the stress-coping model, the aim of the present study was to investigate the relationship between personal resource resilience and psychological distress, and whether appraisals of threat and loss, and passive coping mediate this relationship. Methods: Significant others (n = 228) of persons with SCI or ABI completed questionnaires shortly after admission to first inpatient rehabilitation after onset of the condition. The questionnaire included measures to assess psychological distress (Hospital Anxiety and Depression Scale), resilience (Connor-Davidson Resilience Scale-10), appraisals (Appraisals of Life Events scale, threat and loss) and passive coping (Utrecht Coping List). The PROCESS tool was used to test the presence of mediation. Confounding and differences between SCI and ABI were investigated. Results: High levels of psychological distress among significant others were found (34-41%). Fifty-five percent of the variance in psychological distress was explained by the relationship between resilience and psychological distress. This relationship was mediated by appraisals of threat and loss, and passive coping. The relationship between resilience and psychological distress was similar in the SCI and ABI groups. Conclusions: The results of our study indicate that appraisals of threat and loss and passive coping are mediating factors in the relationship between resilience and psychological distress. It seems useful to investigate if interventions focussing on psychological factors like resilience, appraisal and coping are effective to prevent or reduce psychological distress among significant others of persons with SCI or ABI

Disease-Associated Mutant Ubiquitin Causes Proteasomal Impairment and Enhances the Toxicity of Protein Aggregates

Protein homeostasis is critical for cellular survival and its dysregulation has been implicated in Alzheimer's disease (AD) and other neurodegenerative disorders. Despite the growing appreciation of the pathogenic mechanisms involved in familial forms of AD, much less is known about the sporadic cases. Aggregates found in both familial and sporadic AD often include proteins other than those typically associated with the disease. One such protein is a mutant form of ubiquitin, UBB+1, a frameshift product generated by molecular misreading of a wild-type ubiquitin gene. UBB+1 has been associated with multiple disorders. UBB+1 cannot function as a ubiquitin molecule, and it is itself a substrate for degradation by the ubiquitin/proteasome system (UPS). Accumulation of UBB+1 impairs the proteasome system and enhances toxic protein aggregation, ultimately resulting in cell death. Here, we describe a novel model system to investigate how UBB+1 impairs UPS function and whether it plays a causal role in protein aggregation. We expressed a protein analogous to UBB+1 in yeast (Ubext) and demonstrated that it caused UPS impairment. Blocking ubiquitination of Ubext or weakening its interactions with other ubiquitin-processing proteins reduced the UPS impairment. Expression of Ubext altered the conjugation of wild-type ubiquitin to a UPS substrate. The expression of Ubext markedly enhanced cellular susceptibility to toxic protein aggregates but, surprisingly, did not induce or alter nontoxic protein aggregates in yeast. Taken together, these results suggest that Ubext interacts with more than one protein to elicit impairment of the UPS and affect protein aggregate toxicity. Furthermore, we suggest a model whereby chronic UPS impairment could inflict deleterious consequences on proper protein aggregate sequestration

Congenital hypothyroidism

Congenital hypothyroidism (CH) occurs in approximately 1:2,000 to 1:4,000 newborns. The clinical manifestations are often subtle or not present at birth. This likely is due to trans-placental passage of some maternal thyroid hormone, while many infants have some thyroid production of their own. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. CH is classified into permanent and transient forms, which in turn can be divided into primary, secondary, or peripheral etiologies. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born in areas of endemic iodine deficiency. In countries with newborn screening programs in place, infants with CH are diagnosed after detection by screening tests. The diagnosis should be confirmed by finding an elevated serum TSH and low T4 or free T4 level. Other diagnostic tests, such as thyroid radionuclide uptake and scan, thyroid sonography, or serum thyroglobulin determination may help pinpoint the underlying etiology, although treatment may be started without these tests. Levothyroxine is the treatment of choice; the recommended starting dose is 10 to 15 mcg/kg/day. The immediate goals of treatment are to rapidly raise the serum T4 above 130 nmol/L (10 ug/dL) and normalize serum TSH levels. Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome. Serum TSH and free T4 should be measured every 1-2 months in the first 6 months of life and every 3-4 months thereafter. In general, the prognosis of infants detected by screening and started on treatment early is excellent, with IQs similar to sibling or classmate controls. Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism

Impairment of the tRNA-splicing endonuclease subunit 54 (tsen54) gene causes neurological abnormalities and larval death in zebrafish models of pontocerebellar hypoplasia

Pontocerebellar hypoplasia (PCH) represents a group (PCH1-6) of neurodegenerative autosomal recessive disorders characterized by hypoplasia and/or atrophy of the cerebellum, hypoplasia of the ventral pons, progressive microcephaly and variable neocortical atrophy. The majority of PCH2 and PCH4 cases are caused by mutations in the TSEN54 gene; one of the four subunits comprising the tRNA-splicing endonuclease (TSEN) complex. We hypothesized that TSEN54 mutations act through a loss of function mechanism. At 8 weeks of gestation, human TSEN54 is expressed ubiquitously in the brain, yet strong expression is seen within the telencephalon and metencephalon. Comparable expression patterns for tsen54 are observed in zebrafish embryos. Morpholino (MO) knockdown of tsen54 in zebrafish embryos results in loss of structural definition in the brain. This phenotype was partially rescued by co-injecting the MO with human TSEN54 mRNA. A developmental patterning defect was not associated with tsen54 knockdown; however, an increase in cell death within the brain was observed, thus bearing resemblance to PCH pathophysiology. Additionally, N-methyl-N-nitrosourea mutant zebrafish homozygous for a tsen54 premature stop-codon mutation die within 9 days post-fertilization. To determine whether a common disease pathway exists between TSEN54 and other PCH-related genes, we also monitored the effects of mitochondrial arginyl-tRNA synthetase (rars2; PCH1 and PCH6) knockdown in zebrafish. Comparable brain phenotypes were observed following the inhibition of both genes. These data strongly support the hypothesis that TSEN54 mutations cause PCH through a loss of function mechanism. Also we suggest that a common disease pathway may exist between TSEN54- and RARS2-related PCH, which may involve a tRNA processing-related mechanism.