Ventilatory Chemosensory Drive Is Blunted in the mdx Mouse Model of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is caused by mutations in the DMD gene resulting in an absence of dystrophin in neurons and muscle. Respiratory failure is the most common cause of mortality and previous studies have largely concentrated on diaphragmatic muscle necrosis and respiratory failure component. Here, we investigated the integrity of respiratory control mechanisms in the mdx mouse model of DMD. Whole body plethysmograph in parallel with phrenic nerve activity recordings revealed a lower respiratory rate and minute ventilation during normoxia and a blunting of the hypoxic ventilatory reflex in response to mild levels of hypoxia together with a poor performance on a hypoxic stress test in mdx mice. Arterial blood gas analysis revealed low PaO₂ and pH and high PaCO₂ in mdx mice. To investigate chemosensory respiratory drive, we analyzed the carotid body by molecular and functional means. Dystrophin mRNA and protein was expressed in normal mice carotid bodies however, they are absent in mdx mice. Functional analysis revealed abnormalities in Dejours test and the early component of the hypercapnic ventilatory reflex in mdx mice. Together, these results demonstrate a malfunction in the peripheral chemosensory drive that would be predicted to contribute to the respiratory failure in mdx mice. These data suggest that investigating and monitoring peripheral chemosensory drive function may be useful for improving the management of DMD patients with respiratory failure.     

Proteolytically Inactive Insulin-Degrading Enzyme Inhibits Amyloid Formation Yielding Non-Neurotoxic Aβ Peptide Aggregates

Insulin-degrading enzyme (IDE) is a neutral Zn²⁺ peptidase that degrades short peptides based on substrate conformation, size and charge. Some of these substrates, including amyloid β (Aβ) are capable of self-assembling into cytotoxic oligomers. Based on IDE recognition mechanism and our previous report of the formation of a stable complex between IDE and intact Aβ in vitro and in vivo, we analyzed the possibility of a chaperone-like function of IDE. A proteolytically inactive recombinant IDE with Glu111 replaced by Gln (IDEQ) was used. IDEQ blocked the amyloidogenic pathway of Aβ yielding non-fibrillar structures as assessed by electron microscopy. Measurements of the kinetics of Aβ aggregation by light scattering showed that 1) IDEQ effect was promoted by ATP independent of its hydrolysis, 2) end products of Aβ-IDEQ co-incubation were incapable of “seeding” the assembly of monomeric Aβ and 3) IDEQ was ineffective in reversing Aβ aggregation. Moreover, Aβ aggregates formed in the presence of IDEQ were non-neurotoxic. IDEQ had no conformational effects upon insulin (a non-amyloidogenic protein under physiological conditions) and did not disturb insulin receptor activation in cultured cells. Our results suggest that IDE has a chaperone-like activity upon amyloid-forming peptides. It remains to be explored whether other highly conserved metallopeptidases have a dual protease-chaperone function to prevent the formation of toxic peptide oligomers from bacteria to mammals.     

In vitro efficacy of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> sensu lato against unfed <Emphasis Type="Italic">Amblyomma parvum</Emphasis> (Acari: Ixodidae)

Amblyomma parvum Aragão (Acari: Ixodidae) is a tick species found with wide distribution in the Neotropical region. Even though it is a wildlife-related tick, it is also a frequent parasite of domestic animals, is aggressive to human beings and may harbor pathogenic microorganisms. Therefore, it is a target species for control on domestic animals, particularly those at the rural–wildlife interface. Herein, the efficacy of two isolates (E9 and IBCB 425) of an entomopathogenic fungus, Metarhizium anisopliae sensu lato, already evaluated for ticks that parasitize domestic animals, was tested against unfed A. parvum adults. Both isolates displayed high acaricidal efficacy after immersion in fungal conidial suspensions for 5 min. Isolate E9 killed all ticks by the 7th day post-treatment, and isolate IBCB 425 did so by the 11th day. Tick mortality of 80 and 90% was achieved as early as the 3rd and 4th days, respectively, with both treatments. Thus, if a commercial M. anisopliae s.l. acaricide against domestic animal ticks is developed, it would also be effective against A. parvum.     

Data-Driven Modeling of Intracellular Auxin Fluxes Indicates a Dominant Role of the ER in Controlling Nuclear Auxin Uptake

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Evaluation of diuron tolerance and biotransformation by the white-rot fungus Ganoderma lucidum

The white rot basidiomycete Ganoderma lucidum was evaluated for its capability to tolerate and to degrade the herbicide diuron. Diuron at a subtoxic concentration was added at the start of the cultivation in glucose liquid stationary cultures. Under this condition diuron was a laccase inducer. Almost 50% of the initially present diuron was removed after 15 d of cultivation. Two diuron metabolites were found N′-(3,4-dichlorophenyl)-N-methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU). The addition of the cytochrome P450 inhibitors 1-aminobenzotriazole and piperonyl butoxide reduced significantly the capability of the fungus in degrading diuron. The activities of superoxide dismutase and catalase were significantly increased in the mycelial extracts by the presence of diuron. On the other hand, diuron did not cause any significant alteration in the levels of reactive oxygen species. Additionally, laccase could also degrade diuron in vitro and this degradation was increased by the addition of synthetic mediators, 3-ethylbenzthiazoline-6-sulphonic acid and acetylacetone. Significant reduction in the toxicity, as evaluated by the Lactuca sativa bioassay, was observed after G. lucidum treatment. In conclusion, G. lucidum is able to metabolize diuron by intra- and extracellular mechanisms, without the accumulation of toxic products.     

Adult and nymphs of Microtriatoma trinidadensis (Lent, 1951) (Hemiptera: Reduviidae) caught from peridomestic environment in Bolivia.

This is the first report of adult and nymphs (20 nymphs of all stages and 4 adults) of Microtriatoma trinidadensis (Lent 1951) (Hemiptera: Reduviidae: Triatominae) collected in peridomestic environment, in the department of La Paz, Bolivia. These specimens were associated to Rhodnius stali Lent, Jurberg & Galv?o 1993. The exceptional finding of M. trinidadensis in peridomestic environment, illustrates the general tendency of triatominae to adapt to human dwellings and dependences.     

Histochemical studies of developing human fetal small intestine

Summary The histochemical characteristics of absorptive and mucus-producing cells have been described in 16 specimens of small intestine from human fetuses between 7 and 22 weeks of age. In the youngest specimens a slight to moderate reaction was found for all enzymes examined which included those known from biochemical or ultrastructural studies to be located predominantly in Golgi apparatus (thiamine pyrophosphatase), surface membrane (alkaline phosphatase, adenosine triphosphatase, leucine aminopeptidase), lysosomes (acid phosphatase), and mitochondria (succinic dehydrogenase). Mucus granules of somehat unusual location and staining properties were also found at this time. A progressive intensification of a majority of these histochemical reactions was observed between 3 and 6 fetal months.These findings indicate that the histochemical apparatus for degradation and absorption of nutrients and for elaboration of protein and mucus is already well established in the human fetus by the end of this 6 month period. It is not known, however, whether these activities occur in utero or whether they contribute significantly to fetal nutrition.     

Circulating Interferon Production in the Mouse : Origin and nature of cells involved and influence of animal genotype

A radiobiological study of circulating interferon production in the mouse was undertaken in the hope of elucidating the site(s) of circulating interferon production. After total body X-irradiation of the animals, different radiosensitivities of circulating interferon production were observed with different viral inducers. Myxovirus-induced circulating interferon production was especially radiosensitive. Moreover, a study of interferon production in syngeneic and xenogeneic radiochimeras demonstrated that cells producing NDV (Newcastle disease virus)-induced circulating interferon were derived from hematopoietic stem cells. In addition, treatment of mice with antilymphocyte serum significantly reduced NDV- and Sendai virus-induced circulating interferon, as opposed to other inducers. Taken together, these results strongly suggest that the lymphocyte is the major source of myxovirus-induced circulating interferon. A survey of interferon production in 12 inbred mouse strains, using NDV as inducer, revealed the existence of low and high producers. A Mendelian analysis carried out with low producing Balb/c and high producing C57BL indicated that the difference between low and high interferon producers was caused by a single, autosomal, codominant factor.