Role of transthyretin in thyroxine transfer from cerebrospinal fluid to brain and choroid plexus

The transport of 125I-labeled thyroxine (T4) from the cerebrospinal fluid (CSF) into brain and choroid plexus (CP) was measured in anesthetized rabbit [0.5 mg/kg medetomidine (Domitor) and 10 mg/kg pentobarbitonal sodium (Sagatal) iv] using the ventriculocisternal (V-C) perfusion technique. 125I-labeled T4 contained in artificial CSF was continually perfused into the lateral ventricles for up to 4 h and recovered from the cisterna magna. The %recovery of 125I-labeled T4 from the aCSF was 47.2+/-5.6% (n=10), indicating removal of 125I-labeled T4 from the CSF. The recovery increased to 53.2+/-6.3% (n=4) and 57.8+/-14.8% (n=3), in the presence of 100 and 200 microM unlabeled-T4, respectively (P<0.05), indicating a saturable component to T4 removal from CSF. There was a large accumulation of 125I-labeled T4 in the CP, and this was reduced by 80% in the presence of 200 microM unlabeled T4, showing saturation. In the presence of the thyroid-binding protein transthyretin (TTR), more 125I-labeled T4 was recovered from CSF, indicating that the binding protein acted to retain T4 in CSF. However, 125I-labeled T4 uptake into the ependymal region (ER) of the frontal cortex also increased by 13 times compared with control conditions. Elevation was also seen in the hippocampus (HC) and brain stem. Uptake was significantly inhibited by the presence of endocytosis inhibitors nocodazole and monensin by >50%. These data suggest that the distribution of T4 from CSF into brain and CP is carrier mediated, TTR dependent, and via RME. These results support a role for TTR in the distribution of T4 from CSF into brain sites around the ventricular system, indicating those areas involved in neurogenesis (ER and HC).     

Complex Non-Aerial Contests in the Lekking Butterfly Charis cadytis (Riodinidae)

Lekking butterflies typically defend territories using acrobatic aerial pursuits. Focal-method observations on marked Charis cadytis in SE Brazil revealed an unusual lek organization in which contest males disputed small core areas, whereas non-combative satellite males perched just outside their borders. Territorial interactions commonly began with two adversaries facing one another in a slow, non-contact ascending flight seemingly related to assessment. In disputes that continued, rival males perched on leaves where they engaged in one or more pushing bouts separated by short pursuits. In these sumo-like contests, obliquely facing males pushed their partially opened wings against one another until one was tilted sideways and flew off. Contest structure may be controlled by intruders that, by perching, provoke low-intensity contests that help prolong their stay in high-quality mating areas.     

Lysine residues in N-terminal and C-terminal regions of human histone H2A are targets for biotinylation by biotinidase

In eukaryotic cell nuclei, DNA associates with the core histones H2A, H2B, H3 and H4 to form nucleosomal core particles. DNA binding to histones is regulated by posttranslational modifications of N-terminal tails (e.g., acetylation and methylation of histones). These modifications play important roles in the epigenetic control of chromatin structure. Recently, evidence that biotinidase and holocarboxylase synthetase (HCS) catalyze the covalent binding of biotin to histones has been provided. The primary aim of this study was to identify biotinylation sites in histone H2A and its variant H2AX. Secondary aims were to determine whether acetylation and methylation of histone H2A affect subsequent biotinylation and whether biotinidase and HCS localize to the nucleus in human cells. Biotinylation sites were identified using synthetic peptides as substrates for biotinidase. These studies provided evidence that K9 and K13 in the N-terminus of human histones H2A and H2AX are targets for biotinylation and that K125, K127 and K129 in the C-terminus of histone H2A are targets for biotinylation. Biotinylation of lysine residues was decreased by acetylation of adjacent lysines but was increased by dimethylation of adjacent arginines. The existence of biotinylated histone H2A in vivo was confirmed by using modification-specific antibodies. Antibodies to biotinidase and HCS localized primarily to the nuclear compartment, consistent with a role for these enzymes in regulating chromatin structure. Collectively, these studies have identified five novel biotinylation sites in human histones; histone H2A is unique among histones in that its biotinylation sites include amino acid residues from the C-terminus.     

Cellulose acetates from linters and sisal: correlation between synthesis conditions in DMAc/LiCl and product properties

We report the acetylation of celluloses from sisal (untreated and alkali treated) and cotton linters (alkali treated), under homogeneous solution conditions, using DMAc/LiCl as solvent system. Our target was to evaluate the effects of cellulose dissolution and reactions conditions on the product properties. The products were characterized in terms of degree of substitution (DS) by 1H NMR, and molar weight distribution (MWD) by size exclusion chromatography. Changes in the DS of the products were correlated with reaction conditions and solution properties. It was found that the dissolution of celluloses and degree of substitution of cellulose derivatives depends on a fine adjustment of the dissolution/derivatization conditions, as well as on the origin (sisal or linters) of celluloses.     

Adaptations against heme toxicity in blood-feeding arthropods

A blood-sucking habit appeared independently several times in the course of arthropod evolution. However, from more than a million species of insects and arachnids presently living on earth, only about 14,000 species developed the capacity to feed on vertebrate blood. This figure suggests the existence of severe physiological constraints for the evolution of hematophagy, implying the selective advantage of special adaptations related to the use of blood as a food source. Digestion of vertebrate hemoglobin in the midgut of blood-feeding arthropods results in the production of large amounts of heme, a potentially cytotoxic molecule. Here we will review mechanisms by which heme can exert biological damage, together with a wide spectrum of adaptations developed by blood-feeding insects and ticks to counteract its deleterious effects. In spite of the existence of a great molecular diversity of protective mechanisms, different hematophagous organisms developed convergent solutions that may be physiologically equivalent.     

Inhibition of Ca2+-dependent glutamate release from cerebral cortex synaptosomes of rats with experimental autoimmune encephalomyelitis

Several pathological studies have revealed a prominent involvement of the cerebral cortex in patients with multiple sclerosis (MS). In order to better understand the events that lead to the progressive neuronal dysfunction in MS, herein we explore the contribution of the glutamatergic release in cerebral cortex synaptosomes isolated from rats with experimental autoimmune encephalomyelitis, an animal model reproducing many features of MS. We found that the Ca²⁺-dependent but not the Ca²⁺-independent glutamate release induced by KCl and 4-aminopyridine was significantly decreased during the acute stage of the disease. This inhibited release coincides with the onset of the clinical signs and after 24 h tends to recover the level of the control animals. The results also showed an inhibition of the glutamate release stimulated by ionomycin. When the animals were totally recovered from clinical signs, the neurotransmitter release stimulated by the different inductors was similar to the controls. Examination of the cytosolic Ca²⁺ using fura-2-acetoxymethyl ester revealed that the inhibition of glutamate release could not be attributed to a reduction in voltage-dependent Ca²⁺ influx. However, this inhibition was concomitant with a lower phosphorylation of synapsin I at P-site1. Our results show that the inhibition observed on the Ca²⁺-dependent neurotransmitter release from cerebral cortex synaptosomes in experimental autoimmune encephalomyelitis is specific and correlates with the beginning of the clinical disease. Moreover, they suggest an alteration in the metabolism of proteins involved in the vesicular glutamate release more than a deregulation in the influx of cytosolic Ca²⁺.     

A new capillariid (nematoda) parasitizing Heterandria bimaculata (Heckel, 1848) (Poeciliidae) in Mexico

A new nematode species, Freitascapillaria moraveci n. sp., is described; it was obtained from specimens recovered from the gall bladder of the 2-spot livebearer Heterandrá bimaculata (Heckel, 1848) from La Antigua River, State of Veracruz, Mexico. The new species is assigned to Freitascapillaria Moravec 1982; it is largely characterized by the posterior end of the males, which is laterally expanded without distinct projections. Freitascapillaria moraveci n. sp. differs from the only other species of the genus, F. maxillosa, by the absence of wing-like cells at the esophago-intestinal junction, which are present in the latter species; stichosoma consists of 30-36 stichocytes (F. moraveci) versus 40-60 stichocytes (F. maxillosa) in both males and females and the presence of a well-developed spicule.     

Infection Control Measures to Prevent Invasive Mould Diseases in Hematopoietic Stem Cell Transplant Recipients

Invasive mould diseases, particularly aspergillosis, are important causes of morbidity and mortality in allogeneic stem cell transplant recipients. Mould spores are ubiquitous in the environment. Guidelines established by the Centers for Disease Control (CDC) and other authoritative organizations focus on approaches to reduce exposure to mould spores. These recommendations include avoidance of areas and activities expected to result in high levels of mould spores (e.g., construction, gardening) and use of specially designed units (protected environments) where additional standards (e.g., HEPA-filtered rooms) are in place to minimize mould exposure. These recommendations are based on consensus criteria and limited clinical data largely derived from single-center retrospective studies. In addition, highly immunocompromised stem cell transplant recipients are commonly managed as outpatients, where engineering standards of the inpatient protected environment are not feasible. In the absence of an outbreak with an identified environmental source (e.g., a contaminated air vent), it is not possible to reliably distinguish community-acquired from nosocomial aspergillosis. Adherence to infection control guidelines, acknowledging their limitations, combined with evidence-based targeted antifungal prophylaxis for the highest risk transplant recipients, is likely to be the most effective approach to prevent invasive mould diseases.     

Modifier gene study of meconium ileus in cystic fibrosis: statistical considerations and gene mapping results

Cystic fibrosis (CF) is a monogenic disease due to mutations in the CFTR gene. Yet, variability in CF disease presentation is presumed to be affected by modifier genes, such as those recently demonstrated for the pulmonary aspect. Here, we conduct a modifier gene study for meconium ileus (MI), an intestinal obstruction that occurs in 16–20% of CF newborns, providing linkage and association results from large family and case–control samples. Linkage analysis of modifier traits is different than linkage analysis of primary traits on which a sample was ascertained. Here, we articulate a source of confounding unique to modifier gene studies and provide an example of how one might overcome the confounding in the context of linkage studies. Our linkage analysis provided evidence of a MI locus on chromosome 12p13.3, which was segregating in up to 80% of MI families with at least one affected offspring (HLOD = 2.9). Fine mapping of the 12p13.3 region in a large case–control sample of pancreatic insufficient Canadian CF patients with and without MI pointed to the involvement of ADIPOR2 in MI (p = 0.002). This marker was substantially out of Hardy–Weinberg equilibrium in the cases only, and provided evidence of a cohort effect. The association with rs9300298 in the ADIPOR2 gene at the 12p13.3 locus was replicated in an independent sample of CF families. A protective locus, using the phenotype of no-MI, mapped to 4q13.3 (HLOD = 3.19), with substantial heterogeneity. A candidate gene in the region, SLC4A4, provided preliminary evidence of association (p = 0.002), warranting further follow-up studies. Our linkage approach was used to direct our fine-mapping studies, which uncovered two potential modifier genes worthy of follow-up.