Auditory steady-state evoked potentials (ASSEPs): a study of optimal stimulation parameters for frequency-specific threshold measurement in dogs.

OBJECTIVE: To define the optimal stimulation parameters (AM/FM vs AM alone and modulation rate) for frequency-specific threshold measurements using ASSEPs in dogs. Dependent variables were thresholds and recording times needed to obtain a response at threshold. To compare the ASSEP threshold results obtained with the optimal stimulation parameters to those obtained with the Tone-Burst/Auditory Brainstem Response (TB/ABR) combination. METHODS: Thirty-two sedated Beagle puppies were tested at 5 audiometric frequencies (0.5-8 kHz) and 6 ASSEP modulation rates (21-199 Hz). RESULTS: The ASSEP threshold-modulation rate functions had a high-pass profile with corner frequencies of 101 Hz for 0.5, 1 and 2 kHz carriers and of 151 Hz for 4 and 8 kHz carriers. AM stimuli did not yield higher thresholds than the AM/FM ones except at 1 kHz. Modulation type had no effect on testing duration. Audiometric profiles were obtained much more rapidly with ASSEPs than with TB/ABRs (mean: 50 vs 135 min). Both ASSEP and TB/ABR provided thresholds estimates characterized by low intersubject variability. CONCLUSIONS: ASSEPs are a valid and rapid method for audiometric assessment in sedated dogs. SIGNIFICANCE: ASSEPs offer a new, competitive tool for frequency-specific assessment of hearing in the canine species.     

Mast cell activation involves plasma membrane potential- and thapsigargin-sensitive intracellular calcium pools

Summary— The regulation and role of the intracellular Ca²⁺ pools were studied in rat peritoneal mast cells. Cytosolic free calcium concentration ([Ca²⁺]i) was monitored in fura-2 loaded mast cells. In the presence of Ca²⁺ and K+, compound 48/80 induced a biphasic increase in [Ca²⁺]i composed of a fast transient phase and an apparent sustained phase. The sustained phase was partially inhibited by the addition of Mn²⁺. DTPA, a cell-impermeant chelator of Mn²⁺, reversed this inhibition, suggesting that a quenching of fura-2 fluorescence occurs in the extracellular medium. In the absence of extracellular Ca²⁺, the transient phase, but not the sustained one, could be preserved, provided that mast cells were depolarized. The transient phase was completely abolished by thapsigargin, a microsomal Ca²⁺-ATPase inhibitor. Maximum histamine release induced by either compound 48/80 or antigen was obtained in the absence of added Ca²⁺ only when mast cells were depolarized. These histamine releases were inhibited by low doses (< 30 nM) of thapsigargin. Thapsigargin at higher doses induced histamine release which was unaffected by changing the plasma membrane potential, but was completely dependent on extracellular Ca²⁺, showing that a Ca²⁺ influx is required for thapsigargin-induced exocytosis. Together, these results suggest that the mobilization of Ca²⁺ from thapsigargin sensitive-intracellular pools induced by compound 48/80 or antigen is sufficient to trigger histamine release. The modulation of these pools by the plasma membrane potential suggest their localization is close to the plasma membrane.     

Modulation of calcium homeostasis as a mechanism for altering smooth muscle responsiveness in asthma

Airway hyperresponsiveness remains a defining characteristic of asthma. Traditional views assert that airway smooth muscle is an important structural effector cell in the bronchi that modulates bronchomotor tone induced by contractile agonists. New evidence, however, suggests that abnormalities in airway smooth muscle functions, induced by variety of extracellular stimuli, may play an important role in the development of airway hyperresponsiveness. Studies using isolated bronchial preparations or cultured cells show that inflammatory mediators and cytokines may alter calcium homeostasis in airway smooth muscle and render the cells nonspecifically hyperreactive to agonists.     

Effects of Various Environmental Stress Paradigms and Adrenalectomy on the Expression of Autoimmune Type 1 Diabetes in the Non-obese Diabetic (NOD) Mouse

The effects of long-term chronic stress (induced by repeated restraint, overcrowding or both), short-term chronic stress (induced by a triad of stressors over a short period of time early in life) and adrenalectomy were investigated on the prevalence, on the degree of insulitis and various physiological and immunological parameters in the NOD mouse, a spontaneous model of type I-insulin-dependent diabetes mellitus (IDDM). Long-term chronic stress, obtained by restraint once a week or overcrowding, significantly protected NOD females, while both applied concomitantly had only a tendency to protect against diabetes. In contrast, short-term chronic stress had no significant effect on diabetes expression, whereas adrenalectomy resulted in a trend toward accelerated diabetes onset. The various long-term chronic stress paradigms exerted different effects on the progression of insulitis: repeated restraint tended to protect against insulitis, overcrowding had no effect but, when associated with restraint, significantly counteracted the beneficial effect of restraint alone. Adrenalectomy and short-term chronic stress had no significant effect on the development of insulitis. Various parameters, such as body, thymus and spleen weights, thymus and spleen cellularities, mitogen-induced spleen cell proliferation and serum corticosterone levels were also studied under the various experimental conditions. Taken together, the observations suggest that stressors modulate the expression of spontaneous autoimmune diabetes by exerting pleiotropic effects on immune and/or inflammatory components at the pancreas level and on peripheral glucose metabolism.     

Depression,sleeping pattern,and suicidal ideation among medical students in Bangladesh: a cross-sectional pilot study

Journal of Public Health - Depression is a major morbidity and the most common mental disorder among the medical students in medical schools globally. Undergraduate students suffer stress more due...     

Seminal cell-free DNA and sperm characteristic’s: An added biomarker for male infertility investigation

Cell-free DNA (Cf-DNA) fragments may constitute an easy-to-measure molecular tool for guiding the choice of care provided to infertile couples who benefit assisted reproductive technology (ART) programmes. Data on Cf-DNA levels in the seminal plasma of men with sperm alterations are scarce. The objective of the present study was to quantify the presence of Cf-DNA in semen by using a quantitative real-time PCR. We compared men with abnormal sperm characteristics (n = 21) with normospermic controls (n = 21). The PCR assay evidenced significantly higher mean Cf-DNA levels in patients with sperm abnormalities than in controls (2.09 versus 1.18 µg/ml, respectively; p = .0003). The Cf-DNA levels were notably higher in men with azoospermia (3.65 µg/ml, versus 1.34 µg/ml in matched controls; p = .03) and men with teratozoospermia (1.80 µg/ml, versus 1.29 µg/ml in matched controls; p = .008). Our data report a significant association between elevated Cf-DNA levels and sperm abnormalities. These results may open up new diagnostic and prognostic perspectives in male infertility.     

Development and characterization of naproxen-chitosan solid systems with improved drug dissolution properties.

The solubilizing and amorphizing properties toward naproxen (a poorly water-soluble antiinflammatory drug) of chitosan, an emerging pharmaceutical biopolymer, have been investigated. Solid binary systems at different drug/polymer ratios have been prepared according to different techniques (mixing, cogrinding, kneading, coevaporation) using chitosan at low (CS-L(w)) and medium (CS-M(w)) molecular weight, and tested for dissolution properties. Drug-carrier interactions were investigated in both the liquid and solid state, by phase solubility analysis, differential scanning calorimetry, X-ray powder diffractometry, FT-IR spectroscopy, and scanning electron microscopy. Drug dissolution parameters improved with increasing the polymer amount in the mixture, reaching the highest values at the 1:9 (w/w) drug/polymer ratio, and CS-L(w) was more efficacious than CS-M(w). Cogrinding was the most effective technique, showing the strongest amorphizing effect toward the drug and enabling an increase of more than ten times its relative dissolution rate. Coground mixtures at 3:7 (w/w) drug/polymer ratio were able to give directly compressed tablets which maintained unchanged the improved drug dissolution properties. Enhancer dissolution properties combined with its direct compression feasibility and antiulcerogenic action make CS-L(w) an optimal carrier for developing fast-release oral solid dosage forms of naproxen.     

Le rôle du fenugrec dans la survenue d’anomalie de fermeture du tube neural : un signal d’alerte depuis le Maroc

Fenugreek is among the oldest medicinal and culinary plants. It is widely used in Morocco and the Mediterranean area. In herbal medicine, the seeds of this plant are shown to stimulate appetite in pregnant women to treat inflammation, dysentery, dyspepsia, chronic cough, bronchitis, neuralgia, and facilitate childbirth and also as galactagogue. Unfortunately, few scientific data are available from the literature to confirm therapeutic properties of fenugreek. The early adverse events related to the consumption of this plant were reported between March and August 2006 by the Moroccan Pharmacovigilance Centre; Skalli reported eight cases of malformations (hydrocephalus and spina bifida) coinciding with fenugreek ingestion during pregnancy. A lot of studies have subsequently confirmed this clinical fact. The aim of this study is to report local and national data on the relationship between the consumption of fenugreek during pregnancy and the appearance of neural tube defects based on studies that confirm this relationship.