Melatonin and other antioxidants prolong the postmortem activity of the outer hair cells of the organ of Corti: Its relation to the type of death

The outer hair cells of the organ of Corti transform sound into electrical signals, beginning the nervous auditive process. These cells produce acoustic emissions when working routinely, known as otoacoustic emissions. Otoacoustic emissions (OAEs) are recorded from the hearing duct through a probe which incorporates a sound source and a sensitive microphone. On the other hand, the cochlea produces oxygen-derived free radicals and nitric oxide, in addition, melatonin is present in the cochlea. The authors have studied the influence of melatonin or an antioxidant mixture (alpha-tocopherol acid succinate, ascorbic acid, glutathione, and N-acetylcysteine) on the postmortem activity of the outer hair cells of the organ of Corti of the rat, measuring distortion product otoacoustic emissions. Control rats showed postmortem distortion product otoacoustic emissions for about 2 min when sacrificed by decapitation, and for about 3 min when sacrificed by chloroform inhalation. Melatonin prolonged the postmortem activity 3.5 times when the animals were sacrificed by decapitation, and 7 times when animals were sacrificed by chloroform inhalation. Similar results were obtained with the antioxidant mixture. Results show that melatonin and other antioxidants have, in general, a protective role on the postmortem activity of the outer hair cells of the organ of Corti.     

Localization and level of expression of beta-catenin in human laryngeal squamous cell carcinoma.

OBJECTIVE: We studied the participation of beta-catenin in the histologic differentiation of laryngeal squamous cell carcinomas. STUDY DESIGN AND SETTING: At the National Institute of Respiratory Diseases, a tertiary referral center, localization and level of expression of beta-catenin were compared between normal epithelium (15 cases) and primary tumors in different degrees of differentiation (38 cases), using an immunohistochemical procedure. RESULTS: Cell membrane staining of beta-catenin was observed in normal epithelium and in well and moderately differentiated carcinomas. Cytoplasmic redistribution was observed in poorly differentiated carcinomas. Loss of beta-catenin correlated with tumor dedifferentiation. CONCLUSION: Reduction of cell membrane beta-catenin expression correlated with tumor dedifferentiation. SIGNIFICANCE: Loss of beta-catenin may lead to diminishing the strength of the intercellular adhesion system, thereby promoting the invasive phenotype of the squamous cell carcinoma of the larynx.     

Ototoxicity caused by aminoglycosides is ameliorated by melatonin without interfering with the antibiotic capacity of the drugs

The production of free radicals seems to be involved in the mechanisms of ototoxicity. Aminoglycosides produce ototoxicity, which can be determined through distortion product otoacoustic emissions (OAEs) that measure the activity of the outer hair cells of the organ of Corti. An ototoxic chart was obtained in rats using gentamicin or tobramycin. Together with this treatment, the animals ingested melatonin in the drinking water, or melatonin was injected subcutaneously or intramuscularly. The distortion product OAEs were determined over a prolonged period of time for each of the groups. The effect of melatonin on the antibiotic capacity of the aminoglycosides used was also studied. Antibiograms inoculated with Escherichia coli or Pseudomonas aeruginosa and treated with gentamicin or tobramycin in the presence or absence of melatonin at quantities from pharmacological to physiological doses were performed. The ototoxicity produced by gentamicin and tobramycin was maximal from days 3 to 5 post-treatment, returning to normal values in 2 wk. When melatonin was present, the recovery was at day 5 post-treatment, independently of the means of administration of the pineal product. The antibiograms showed that melatonin had no effect on the antibiotic capacity. It is concluded that the ototoxicity caused by gentamicin and tobramycin is ameliorated by melatonin and that the pineal hormone does not interfere with the antibiotic capacity of these antibiotics.     

Difficulties in Emotion Regulation,Coping, and Dysfunctional Psychological Symptoms in Family Members of People with Gambling Disorder

Gambling disorder not only affects those who suffer from it but also has consequences for their families. Considering such repercussions are often understudied, and the aim of the present study was to evaluate the main differences between family members of people with gambling disorder (GDFMs) and those with no relatives diagnosed with gambling disorder (non-GDFMs). The variables examined in the present study included emotion regulation, coping strategies, depression, and anxiety. The sample (N = 203) was divided into two groups. This comprised a clinical group (n = 89 participants, 43.8% of the sample), with 69.7% of women (M_age = 48.63, SD = 13.36), and a community sample (i.e., no gambling-related problems in their family; n = 114, representing 56.2% of the sample), containing 64% of women (M_age = 35.89, SD = 11.45). Results showed that GDFMs scored significantly higher than non-GDFMs (i) on anxiety and depression scales, (ii) on difficulties in emotion regulation, and (iii) on maladaptive coping strategies. Additionally, difficulties in emotion regulation and coping strategies correlated with anxiety and depression. Regression analyses showed that difficulties in emotion regulation and coping strategies predicted anxiety and depression for GDFMs. These findings highlight the importance of including family members as part of the target group in gambling disorder treatment protocols.

     

Sulpiride plus hydroxyzine decrease tinnitus perception

OBJECTIVES: The aim of the study is to confirm the effectiveness of sulpiride and hydroxyzine in tinnitus patients. The administration of sulpiride, a D2 antagonist of dopamine receptors, together with hydroxyzine, a subcortical sedative, covers the areas of tinnitus perception. METHODS: A prospective, randomized, single blinded, placebo-control study was done in general otorhinolaryngology consultations for 2002-2004 in Seville and Zaragoza (Spain). One hundred and fifty patients consulted for subjective tinnitus. They were included randomly in three groups of 50. A group took sulpiride (50 mg/8 h) alone, other the same dose of sulpiride plus hydroxyzine (25 mg/12 h), and the third placebo (lactose), for 1 month. One hundred and twenty-two patients completed the study. Clinical history, tonal audiometry, tympanometry, and tinnitometry were done in the beginning and end of the study. Subjective Grading of Tinnitus Perception and visual analogical scale (0-10) were done for result evaluation. RESULTS: Based on the Subjective Grading of Tinnitus Perception, tinnitus perception diminished by 56% in patients treated with sulpiride and by 81% in patients treated with sulpiride plus hydroxyzine. Based on the visual analogical scale, tinnitus perception diminished from 7.8 to 6.3 in the patients treated with sulpiride, and from 7.8 to 5.1 in those treated with sulpiride plus hydroxyzine. CONCLUSIONS: Sulpiride plus hydroxyzine decreases tinnitus perception. Tinnitus auditolimbic dopaminergic pathway opens wide therapeutical implications.     

Cavbeta-subunit displacement is a key step to induce the reluctant state of P/Q calcium channels by direct G protein regulation

P/Q Ca(2+) channel activity is inhibited by G protein-coupled receptor activation. Channel inhibition requires a direct Gbetagamma binding onto the pore-forming subunit, Ca(v)2.1. It is characterized by biophysical changes, including current amplitude reduction, activation kinetic slowing, and an I-V curve shift, which leads to a reluctant mode. Here, we have characterized the contribution of the auxiliary beta(3)-subunit to channel regulation by G proteins. The shift in I-V to a P/Q reluctant mode is exclusively observed in the presence of beta(3). Along with the observation that Gbetagamma has no effect on the I-V curve of Ca(v)2.1 alone, we propose that the reluctant mode promoted by Gbetagamma corresponds to a state in which the beta(3)-subunit has been displaced from its channel-binding site. We validate this hypothesis with a beta(3)-I-II(2.1) loop chimera construct. Gbetagamma binding onto the I-II(2.1) loop portion of the chimera releases the beta(3)-binding domain and makes it available for binding onto the I-II loop of Ca(v)1.2, a G protein-insensitive channel. This finding is extended to the full-length Ca(v)2.1 channel by using fluorescence resonance energy transfer. Gbetagamma injection into Xenopus oocytes displaces a Cy3-labeled beta(3)-subunit from a GFP-tagged Ca(v)2.1 channel. We conclude that beta-subunit dissociation from the channel complex constitutes a key step in P/Q calcium channel regulation by G proteins that underlies the reluctant state and is an important process for modulating neurotransmission through G protein-coupled receptors.     

Interaction of melatonin with human lymphocytes: Evidence for binding sites coupled to potentiation of cyclic AMP stimulated by vasoactive intestinal peptide and activation of cyclic GMP

Melatonin binding sites were characterized in human blood lymphocytes. The specific binding 2-[125I]iodo-melatonin ([125I]MEL) to human lymphocytes was dependent on time and temperature, stability, saturation, and reversibility. Moreover, guanine nucleotides decreased the specific binding of [125I]MEL to crude membranes of human lymphocytes, suggesting the coupling of these binding sites to a guanosine nucleotide binding regulatory protein(s). In competition studies, the specific binding of [125I]MEL to lymphocytes was inhibited by increasing concentrations of native melatonin. Scatchard analysis showed that data were compatible with the existence of two classes of binding sites: a high-affinity site with a Kd of 5.20 +/- 0.79 nM and a binding capacity of 50.6 +/- 11.0 fmol/10(7) cells, and a low-affinity site with a Kd of 208.5 +/- 50.2 nM and a binding capacity of 2691 +/- 265 fmol/10(7) cells. However, concentration-dependent binding of [125I]MEL to lymphocytes was saturable and resulted in a linear Scatchard plot, suggesting binding to a single class of binding sites. The Kd for the single site was 1.02 +/- 0.34 nM with a binding capacity of 10.1 +/- 1.6 fmol/10(7) cells. Their affinities closely correlated with the production of cyclic nucleotides, suggesting a physiological role for the melatonin binding sites. Thus, melatonin potentiated the effect of vasoactive intestinal peptide (VIP) on cyclic AMP production (ED50 = 1.9 nM) and stimulated cyclic GMP accumulation (ED50 = 125 nM). Results demonstrate the existence of two binding sites for [125I]MEL in human blood lymphocytes, with a high-affinity binding site coupled to the potentiation of the effect of VIP on cyclic AMP production and a low-affinity binding site coupled to activation of cyclic GMP production.     

Stroke penumbra defined by an MRI-based oxygen challenge technique: 2. Validation based on the consequences of reperfusion

Magnetic resonance imaging (MRI) with oxygen challenge (T₂^* OC) uses oxygen as a metabolic biotracer to define penumbral tissue based on CMRO₂ and oxygen extraction fraction. Penumbra displays a greater T₂^* signal change during OC than surrounding tissue. Since timely restoration of cerebral blood flow (CBF) should salvage penumbra, T₂^* OC was tested by examining the consequences of reperfusion on T₂^* OC-defined penumbra. Transient ischemia (109±20 minutes) was induced in male Sprague-Dawley rats (n=8). Penumbra was identified on T₂^*-weighted MRI during OC. Ischemia and ischemic injury were identified on CBF and apparent diffusion coefficient maps, respectively. Reperfusion was induced and scans repeated. T₂ for final infarct and T₂^* OC were run on day 7. T₂^* signal increase to OC was 3.4% in contralateral cortex and caudate nucleus and was unaffected by reperfusion. In OC-defined penumbra, T₂^* signal increased by 8.4%±4.1% during ischemia and returned to 3.25%±0.8% following reperfusion. Ischemic core T₂^* signal increase was 0.39%±0.47% during ischemia and 0.84%±1.8% on reperfusion. Penumbral CBF increased from 41.94±13 to 116.5±25 mL per 100 g per minute on reperfusion. On day 7, OC-defined penumbra gave a normal OC response and was located outside the infarct. T₂^* OC-defined penumbra recovered when CBF was restored, providing further validation of the utility of T₂^* OC for acute stroke management.