Rapid Effects of Hearing Song on Catecholaminergic Activity in the Songbird Auditory Pathway

Catecholaminergic (CA) neurons innervate sensory areas and affect the processing of sensory signals. For example, in birds, CA fibers innervate the auditory pathway at each level, including the midbrain, thalamus, and forebrain. We have shown previously that in female European starlings, CA activity in the auditory forebrain can be enhanced by exposure to attractive male song for one week. It is not known, however, whether hearing song can initiate that activity more rapidly. Here, we exposed estrogen-primed, female white-throated sparrows to conspecific male song and looked for evidence of rapid synthesis of catecholamines in auditory areas. In one hemisphere of the brain, we used immunohistochemistry to detect the phosphorylation of tyrosine hydroxylase (TH), a rate-limiting enzyme in the CA synthetic pathway. We found that immunoreactivity for TH phosphorylated at serine 40 increased dramatically in the auditory forebrain, but not the auditory thalamus and midbrain, after 15 min of song exposure. In the other hemisphere, we used high pressure liquid chromatography to measure catecholamines and their metabolites. We found that two dopamine metabolites, dihydroxyphenylacetic acid and homovanillic acid, increased in the auditory forebrain but not the auditory midbrain after 30 min of exposure to conspecific song. Our results are consistent with the hypothesis that exposure to a behaviorally relevant auditory stimulus rapidly induces CA activity, which may play a role in auditory responses

First Report of Disseminated Mycobacterium Skin Infections in Two Liver Transplant Recipients and Rapid Diagnosis by hsp65 Gene Sequencing ▿

We present here the first report of disseminated skin Mycobacterium infections in two liver transplant recipients, in which hsp65 gene sequencing was used for rapid species identification. Both patients had hepatitis B virus-related cirrhosis and diabetes mellitus and presented with progressive generalized, nodular skin lesions. In one patient, a 50-year-old woman who had frequent contact with marine fish, an acid-fast bacillus was isolated from skin biopsy tissue after 2 months of culture. While awaiting phenotypic identification results, hsp65 gene sequencing showed that it was most closely related to that of Mycobacterium marinum with 100% nucleotide identity. The patient was treated with oral rifampin, ethambutol, and moxifloxacin. In the other patient, a 59-year-old woman, direct PCR for Mycobacterium using hsp65 gene from skin biopsy tissue was positive, with the sequence most closely related to that of M. haemophilum with 100% nucleotide identity. Based on PCR results, the patient was treated with clarithromycin, ethambutol, moxifloxacin, and amikacin. A strain of M. haemophilum was only isolated after 3 months. Skin lesions of both patients resolved after 1 year of antimycobacterial therapy. Nontuberculous Mycobacterium infections should be considered in liver transplant recipients presenting with chronic, nodular skin lesions. This report highlights the crucial role of hsp65 gene PCR and sequencing on both cultured isolates and direct clinical specimens for rapid diagnosis of slow-growing Mycobacterium infection