Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses

The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse’s respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (PSA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified “subclinical” subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically

Clustering of metabolic syndrome components in a Middle Eastern diabetic and non-diabetic population

<p>Abstract</p> <p>Background</p> <p>Metabolic syndrome (MetS) encompasses a cluster of coronary heart disease and diabetes mellitus risk factors. In this study, we aimed to elucidate the factors underlying the clustering of MetS components in diabetic and non-diabetic individuals.</p> <p>Methods</p> <p>Factor analysis was performed on 2978 (1652 non-diabetic and 1326 diabetic) participants. Entering waist circumference, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, high-density lipoprotein-cholesterol (HDL-C) and systolic blood pressure (SBP), we performed exploratory factor analysis in diabetic and non-diabetic individuals separately. The analysis was repeated after replacing triglycerides and HDL-C with triglycerides to HDL-C ratio (triglycerides/HDL-C). MetS was defined by either adult treatment panel III (ATPIII), international diabetes federation (IDF) criteria, or by the modified form of IDF using waist circumference cut-off points for Iranian population.</p> <p>Results</p> <p>The selection of triglycerides and HDL-C as two distinct variables led to identifying two factors explaining 61.3% and 55.4% of the total variance in non-diabetic and diabetic participants, respectively. In both diabetic and non-diabetic subjects, waist circumference, HOMA-IR and SBP loaded on factor 1. Factor 2 was mainly determined by triglycerides and HDL-C. Factor 1 and 2 were directly and inversely associated with MetS, respectively. When triglycerides and HDL-C were replaced by triglycerides/HDL-C, one factor was extracted, which explained 47.6% and 38.8% of the total variance in non-diabetic and diabetic participants, respectively.</p> <p>Conclusion</p> <p>This study confirms that in both diabetic and non-diabetic participants the concept of a single underlying factor representing MetS is plausible.</p

Effects of nitric oxide on diaphragmatic muscle endurance and strength in pigs

The aim of the study was to evaluate the effects of nitric oxide (NO) on diaphragmatic fatigue in fifteen anaesthetized, mechanically ventilated pigs, divided into three groups. The animals were pre-treated with indomethacin (3 mg kg-1, i.v.) to block the cyclo-oxygenase pathway. To group 1 pigs (n = 6) NG-nitro-L-arginine methyl ester (L-NAME, 5 mg kg-1 i.v.) was administered as a bolus to block endogenous NO production, while group 2 pigs (n = 6) were infused with sodium nitroprusside (SNP, 0.023 mg kg-1, i.v.), a donor of NO. Group 3 pigs (n = 3) were used as the controls. We evaluated diaphragmatic strength by measuring the transdiaphragmatic pressure (P di) generated during bilateral phrenic nerve stimulation at 10, 20, 30 and 50 Hz, 15 V, while the diaphragmatic endurance was assessed by a 30s stimulation at 10 Hz, 15 V. Diaphragmatic index was assessed as the ratio of peak force between single twitches performed before and after the 30 s stimulation west. We also evaluated mean systemic (MAP) and pulmonary (MPAP) arterial pressures, pulmonary wedge pressure (PW), systemic (SVR) and pulmonary vascular resistance (PVR) and cardiac output (CO). L-NAME increased MAP, MPAP, PW, SVR and PVR, but decreased CO. SNP caused a decrease in MAP, MPAP, PW and SVR, while PVR and CO did not change. The main finding of this study was that diaphragmatic strength was not significantly weakened after L-NAME administration, except at 10 Hz, while it did not change after SNP infusion. However, both L-NAME and SNP caused significant decreases in diaphragmatic endurance capacity. The fatigue appearing after L-NAME is probably correlated with a decline in diaphragmatic blood flow, as evidenced by the increase in SVR and the decrease in CO, and consequently in oxygen supply. In contrast, the decrease in endurance capacity after SNP infusion can be attributed to a direct action of NO on skeletal muscle