Aerospace systems and mission analysis research - Solar electric space mission analysis Final report

Mission analysis for solar electric propelled spacecraft on Mars Orbiter, Jupiter flyby, and asteroid belt exploration trajectorie

Altered expression of Alzheimer\u27s disease-related proteins in male hypogonadal mice

Age-related depletion of estrogens and androgens is associated with an increase in Alzheimer\u27s disease (AD) brain pathology and diminished cognitive function. Here we investigated AD-associated molecular and cellular changes in brains of aged hypogonadal (hpg) male and female mice. hpg Mice have a spontaneous, inactivating genetic mutation in the GnRH gene resulting in lifelong deficiency of gonadotropins and gonadal sex hormones. Western blot analysis revealed low levels of amyloid precursor protein and high levels of presenilin 1, amyloid precursor protein C-terminal fragment, and β-amyloid 42 in brains of aged male, but not female, hpg mice. Changes were confined to the hippocampus and were not evident in the cerebellum or other brain tissues. Male hpg mice tended to have lower levels of IL-1β protein than male littermate controls. Immunohistochemical staining of the basal forebrain revealed that male hpg mice had lower choline acetyltransferase levels per neuron compared with controls. These AD-like changes specific to male hpg mice supports a link between androgen depletion and the development of AD pathology

Robustness of the Bacterial Community in the Cabbage White Butterfly Larval Midgut

Microbial communities typically vary in composition and structure over space and time. Little is known about the inherent characteristics of communities that govern various drivers of these changes, such as random variation, changes in response to perturbation, or susceptibility to invasion. In this study, we use 16S ribosomal RNA gene sequences to describe variation among bacterial communities in the midguts of cabbage white butterfly (Pieris rapae) larvae and examine the influence of community structure on susceptibility to invasion. We compared communities in larvae experiencing the same conditions at different times (temporal variation) or fed different diets (perturbation). The most highly represented phylum was Proteobacteria, which was present in all midgut communities. The observed species richness ranged from six to 15, and the most abundant members affiliated with the genera Methylobacteria, Asaia, Acinetobacter, Enterobacter, and Pantoea. Individual larvae subjected to the same conditions at the same time harbored communities that were highly similar in structure and membership, whereas the communities observed within larval populations changed with diet and over time. In addition, structural changes due to perturbation coincided with enhanced susceptibility to invasion by Enterobacter sp. NAB3R and Pantoea stewartii CWB600, suggesting that resistance to invasion is in part governed by community structure. These findings along with the observed conservation of membership at the phylum level, variation in structure and membership at lower taxonomic levels, and its relative simplicity make the cabbage white butterfly larval community an attractive model for studying community dynamics and robustness

Blood testosterone threshold for androgen deficiency symptoms.

There are few systematic studies of the relationship between blood testosterone concentrations and the symptoms of overt androgen deficiency. Because most testosterone preparations are relatively short-term, the rapid changes in blood testosterone concentrations they cause make it difficult to define any testosterone threshold. By contrast, subdermal testosterone implants provide stable blood testosterone concentrations over days to weeks, while gradually declining to baseline over 5-7 months. Hence, this provides an opportunity to define a blood testosterone threshold for androgen deficiency symptoms by observing androgen-deficient men as their familiar androgen deficiency symptoms return as testosterone pellets slowly dissolve. Among 52 androgen-deficient men who underwent 260 implantations over 5 yr, at the time of return of androgen deficiency symptoms the blood total and free testosterone concentrations were highly reproducible within individuals (F ‫؍‬ 0.8, P ‫؍‬ 0.49 and F ‫؍‬ 1.4, 0.24, respectively) but varied markedly between men (F ‫؍‬ 167 and F ‫؍‬ 138, both P < 0.001), indicating that each person had a consistent testosterone threshold for androgen deficiency symptoms that differed markedly between individuals. The most reported symptoms of androgen deficiency were lack of energy, lack of motivation, and reduced libido. The symptomatic threshold was significantly lower in men with secondary hypogonadism compared with men with primary or mixed hypogonadism (total, 9.7 ؎ 0.5 nmol/liter vs. T HE EFFECTS OF androgen deficiency and replacement on objective endpoints, notably bone (1, 2) and muscle (3-7), are well known and increasingly studied. Yet, whereas symptoms of androgen deficiency are discussed in textbooks and form the basis for practical clinical monitoring of androgen replacement therapy (8), there is a paucity of systematic studies of the symptoms of, and symptomatic threshold for, androgen deficiency. The subjective effects of androgen deficiency and replacement have generally been studied as objectively recorded measures of mood, behavior and cognitive responses (9 -11), but symptoms themselves are more difficult to study objectively. As a result, subjective effects of androgens have received most attention in the psychology literature, where empirical studies are, however, largely observational and restricted to eugonadal men limiting the salience of any inferences regarding relationships of blood testosterone concentrations to symptoms of overt androgen deficiency. A major limitation of interventional clinical research on androgen deficiency symptoms is that the available relatively short-term testosterone preparations produce swings in blood testosterone levels over days to weeks, which make it difficult or impossible to distinguish reliably symptom resolution and reappearance from pharmacological effects. The present study overcomes this limitation by using a long-acting depot testosterone preparation, which maintains stable blood testosterone concentrations over days to weeks but, as the biodegradable implants erode, allows them to decline slowly back to baseline over 5-7 months (12-15). Because the treated men return for blood testosterone measurement and reimplantation when their familiar androgen deficiency symptoms return, this allows a prospective evaluation of the relationships between individual androgen deficiency symptoms and the blood testosterone concentrations that accompany them. Subjects and Methods Patients We reviewed prospectively collected data from patients having regular androgen replacement therapy with a standard dose (four 200-mg pellets) of subdermal testosterone implants for androgen deficiency as described previously Procedures Implantation procedure. Testosterone pellet implantation procedures are booked throughout the week. At visits, men have a blood sample drawn JCEM is published monthly by The Endocrine Society (http://www. endo-society.org), the foremost professional society serving the endocrine community

Some Remarks on Effective Range Formula in Potential Scattering

In this paper, we present different proofs of very recent results on the necessary as well as sufficient conditions on the decrease of the potential at infinity for the validity of effective range formulas in 3-D in low energy potential scattering (Andr\'e Martin, private communication, to appear. See Theorem 1 below). Our proofs are based on compact formulas for the phase-shifts. The sufficiency conditions are well-known since long. But the necessity of the same conditions for potentials keeping a constant sign at large distances are new. All these conditions are established here for dimension 3 and for all angular momenta $\ell \geq 0$

Contributions of gut bacteria to Bacillus thuringiensis-induced mortality vary across a range of Lepidoptera

Abstract Background Gut microbiota contribute to the health of their hosts, and alterations in the composition of this microbiota can lead to disease. Previously, we demonstrated that indigenous gut bacteria were required for the insecticidal toxin of Bacillus thuringiensis to kill the gypsy moth, Lymantria dispar. B. thuringiensis and its associated insecticidal toxins are commonly used for the control of lepidopteran pests. A variety of factors associated with the insect host, B. thuringiensis strain, and environment affect the wide range of susceptibilities among Lepidoptera, but the interaction of gut bacteria with these factors is not understood. To assess the contribution of gut bacteria to B. thuringiensis susceptibility across a range of Lepidoptera we examined larval mortality of six species in the presence and absence of their indigenous gut bacteria. We then assessed the effect of feeding an enteric bacterium isolated from L. dispar on larval mortality following ingestion of B. thuringiensis toxin. Results Oral administration of antibiotics reduced larval mortality due to B. thuringiensis in five of six species tested. These included Vanessa cardui (L.), Manduca sexta (L.), Pieris rapae (L.) and Heliothis virescens (F.) treated with a formulation composed of B. thuringiensis cells and toxins (DiPel), and Lymantria dispar (L.) treated with a cell-free formulation of B. thuringiensis toxin (MVPII). Antibiotics eliminated populations of gut bacteria below detectable levels in each of the insects, with the exception of H. virescens, which did not have detectable gut bacteria prior to treatment. Oral administration of the Gram-negative Enterobacter sp. NAB3, an indigenous gut resident of L. dispar, restored larval mortality in all four of the species in which antibiotics both reduced susceptibility to B. thuringiensis and eliminated gut bacteria, but not in H. virescens. In contrast, ingestion of B. thuringiensis toxin (MVPII) following antibiotic treatment significantly increased mortality of Pectinophora gossypiella (Saunders), which was also the only species with detectable gut bacteria that lacked a Gram-negative component. Further, mortality of P. gossypiella larvae reared on diet amended with B. thuringiensis toxin and Enterobacter sp. NAB3 was generally faster than with B. thuringiensis toxin alone. Conclusion This study demonstrates that in some larval species, indigenous gut bacteria contribute to B. thuringiensis susceptibility. Moreover, the contribution of enteric bacteria to host mortality suggests that perturbations caused by toxin feeding induce otherwise benign gut bacteria to exert pathogenic effects. The interaction between B. thuringiensis and the gut microbiota of Lepidoptera may provide a useful model with which to identify the factors involved in such transitions.http://deepblue.lib.umich.edu/bitstream/2027.42/112871/1/12915_2008_Article_219.pd

Requirement for specific gravity and creatinine adjustments for urinary steroids and luteinizing hormone concentrations in adolescents

Objectives: Urinary hormone concentrations are often adjusted to correct for hydration status. We aimed to determine whether first morning void urine hormones in growing adolescents require adjustments and, if so, whether urinary creatinine or specific gravity (SG) are better adjustments. Design and Methods: The study population was adolescents aged 10.1 to 14.3 years initially who provided fasting morning blood samples at 0 and 12 months (n=343) and first morning urine every three months (n=644). Unadjusted, creatinine and SG-adjusted hormonal concentrations were compared by Deming regression and Bland-Altman analysis and grouped according to self-rated Tanner stage or chronological age. F-ratios for self-rated Tanner stages and age groups were used to compare unadjusted and adjusted hormonal changes in growing young adolescents. Correlations of paired serum and urinary hormonal concentration of unadjusted and creatinine and SG adjusted were also compared. Results: Fasting first morning void hormone concentrations correlated well and were unbiased between unadjusted or adjusted by either creatinine or SG. Urine creatinine concentration increases with Tanner stages, age and male gender whereas, urine SG was not influenced by Tanner stage, age or gender. Adjustment by creatinine or SG of urinary luteinizing hormone, estradiol, testosterone, dihydrotestosterone and dehydroepiandrosterone concentrations did not improve correlation with paired serum concentrations. Conclusions: Urine steroid and LH concentrations in first morning void samples of adolescents are not significantly influenced by hydration status and may not require adjustments; however, if desired, both creatinine and SG adjustments are equally suitable

Adolescent testosterone influences BDNF and TrkB mRNA and neurotrophin–interneuron marker relationships in mammalian frontal cortex

AbstractLate adolescence in males is a period of increased susceptibility for the onset of schizophrenia, coinciding with increased circulating testosterone. The cognitive deficits prevalent in schizophrenia may be related to unhealthy cortical interneurons, which are trophically dependent on brain derived neurotrophic factor. We investigated, under conditions of depleted (monkey and rat) and replaced (rat) testosterone over adolescence, changes in gene expression of cortical BDNF and TrkB transcripts and interneuron markers and the relationships between these mRNAs and circulating testosterone. Testosterone removal by gonadectomy reduced gene expression of some BDNF transcripts in monkey and rat frontal cortices and the BDNF mRNA reduction was prevented by testosterone replacement. In rat, testosterone replacement increased the potential for classical TrkB signalling by increasing the full length to truncated TrkB mRNA ratio, whereas in the monkey cortex, circulating testosterone was negatively correlated with the TrkB full length/truncated mRNA ratio. We did not identify changes in interneuron gene expression in monkey frontal cortex in response to gonadectomy, and in rat, we showed that only somatostatin mRNA was decreased by gonadectomy but not restored by testosterone replacement. We identified complex and possibly species-specific, relationships between BDNF/TrkB gene expression and interneuron marker gene expression that appear to be dependent on the presence of testosterone at adolescence in rat and monkey frontal cortices. Taken together, our findings suggest there are dynamic relationships between BDNF/TrkB and interneuron markers that are dependent on the presence of testosterone but that this may not be a straightforward increase in testosterone leading to changes in BDNF/TrkB that contributes to interneuron health