Tyrosine hydroxylase expression in primary cultures of olfactory bulb: role of L-type calcium channels

Sensory activity mediates regulation of tyrosine hydroxylase (TH), the first enzyme in the dopamine biosynthetic pathway, in the rodent olfactory bulb. The current studies established for the first time primary cultures of neonatal mouse olfactory bulb expressing TH and tested whether L-type calcium channels mediate the activity-dependent regulation of the dopamine phenotype. After 1 d in vitro (DIV), a small population of TH-immunostained neurons that lacked extensive processes could be demonstrated. After an additional 2 DIV in serum-free medium, the number of TH neurons had doubled, and they exhibited long interdigitating processes. Membrane depolarization for 48 hr with 50 mM KCl produced a further 2.4-fold increase in the number of TH-immunoreactive neurons compared with control cultures. Increased TH neuron number required at least 36 hr of exposure to KCl. Forskolin, which increases intracellular cAMP levels, induced a 1.5- to 1.6-fold increase in the number of TH-immunostained neurons. Combined treatment with KCl and forskolin was not additive. Nifedipine, an L-type calcium channel blocker, completely prevented the depolarization-mediated increase in TH expression but did not block the response to forskolin. Treatment with Bay K8644, an L-type calcium channel agonist, also significantly increased the number of TH-expressing neurons. Depolarization also induced alterations in neuritic outgrowth, resulting in a stellate versus an elongate morphology that, in contrast, was not prevented by nifedipine. These results are the first demonstration that in vitro, as in vivo, depolarization increases TH expression in olfactory bulb and that L-type calcium channels mediate this activity-dependent regulation of the dopamine phenotype.     

Collaborative cross-checking to enhance resilience

Resilience, the ability to adapt or absorb disturbance, disruption, and change, may be increased by team processes in a complex, socio-technical system. In particular, collaborative cross-checking is a strategy where at least two individuals or groups with different perspectives examine the others’ assumptions and/or actions to assess validity or accuracy. With this strategy, erroneous assessments or actions can be detected quickly enough to mitigate or eliminate negative consequences. In this paper, we seek to add to the understanding of the elements that are needed in effective cross-checking and the limitations of the strategy. We define collaborative cross-checking, describe in detail three healthcare incidents where collaborative cross-checks played a key role, and discuss the implications of emerging patterns.     

Effect of chrysotile-asbestos and zeolites dust on generations of reactive oxygen species by alveolar macrophages and granulocytes

OBJECTIVE: To evaluate the discrepancy index between the clinical and histological diagnosis and the prevalence of epithelial dysplasia and carcinoma in 45 patients with potentially malignant epithelial oral lesions (PMEL). PATIENTS AND METHODS: We submitted 45 patients with PMEL to clinical examination and obtained a biopsy from each. The results of histological diagnosis were compared to the clinical diagnosis. RESULTS: Clinical diagnosis showed that the most common PMEL was leukoplakia followed by lichen planus and by actinic cheilitis associated with leukoplakia. The most common site was the buccal mucosa. Histological diagnosis revealed that 46.7% of the PMEL were lichen planus. The discrepancy index between clinical and histological diagnosis was 24.4%. The higher discrepancy index occurred among leukoplakias. The prevalence of epithelial dysplasia and carcinoma was 17.8%. CONCLUSIONS: We conclude that all PMEL should be submitted to a microscopic analysis because the discrepancy between clinical and histological diagnosis was present in a quarter of these lesions. Otherwise, the epithelial dysplasia and carcinoma were more frequent in the leukoplakias.     

Chlorisondamine inhibits the nicotine-induced stimulation of c-fos in the pigeon brain for up to 2 weeks.

Chlorisondamine is a charged molecule that acts as long-acting nicotinic antagonist in many species, including pigeon. Evidence indicates that, despite the charged nature of chlorisondamine, it blocks some central effects of nicotine. The present study examined the time course of chlorisondamine's blockade of nicotine-induced c-fos expression in the pigeon brain. Chlorisondamine's central blockade was examined from 1 hr to 28 days prior to nicotine administration. Nicotine stimulated increases in c-fos mRNA in the hippocampus, hyperstriatum accessorium, hyperstriatum ventrale, nucleus accumbens, bulbus olfactorius, paleostriatum augmentatum, and stratum griseum et fibrosum superficiale. Nicotinic receptors labeled by [(125)I]-epibatidine were not always found in the same regions as nicotine-induced increases in c-fos expression. Acute chlorisondamine increased the level of c-fos mRNA in the cerebellum, hippocampus, hyperstriatum accessorium, locus parolfactorius, nucleus accumbens, tectum opticum, paleostriatum augmentatum, and stratum griseum et fibrosum superficiale but had no effect on its own 24 hr after administration. Chlorisondamine blocked nicotine-induced increases in c-fos RNA for 4 days in the nucleus accumbens, a week in the bulbus olfactorius, and 2 weeks in the stratum griseum et fibrosum superficiale. The time course of chlorisondamine's blockade of nicotine-induced c-fos expression is consistent with the time course of the ability of chlorisondamine to block behavioral and physiological responses to nicotine.     

Identification and characterization of a two-component regulatory system involved in invasion of eukaryotic cells and heavy-metal resistance in Burkholderia pseudomallei

Burkholderia pseudomallei is the causative agent of melioidosis, a disease increasingly recognized as an important cause of morbidity and mortality in many regions of the world. B. pseudomallei is a facultative intracellular pathogen capable of invading eukaryotic cells. We used Tn5-OT182 mutagenesis to generate mutants deficient in the ability to invade a human type II pneumocyte cell line (A549 cells). One of these mutants, AJ1D8, exhibited approximately 10% of the ability of the parental strain, 1026b, to invade A549 cells. There was no difference in the abilities of 1026b and AJ1D8 to resist killing by RAW macrophages or the human defensin HNP-1. The nucleotide sequence flanking the Tn5-OT182 integration in AJ1D8 was determined, and two open reading frames were identified. The predicted proteins shared considerable homology with two-component regulatory systems involved in the regulation of heavy-metal resistance in other organisms. AJ1D8 was 16-fold more sensitive to Cd2+ and twofold more sensitive to Zn2+ than was 1026b but was not sensitive to any of the other heavy metals examined. The B. pseudomallei two-component regulatory system, termed irlRS, complemented the invasion-deficient and heavy-metal-sensitive phenotype of AJ1D8 in trans. There was no significant difference between the virulence of AJ1D8 and that of 1026b in infant diabetic rats and Syrian hamsters, suggesting that the irlRS locus is probably not a virulence determinant in these animal models of acute B. pseudomallei infection.