Are speech-evoked auditory brainstem response (speech-ABR) outcomes influenced by ethnicity?

Due to its objective nature, auditory brainstem response (ABR) evoked by complex stimuli has been gaining attention lately. The present study aimed to compare the speech-evoked auditory brainstem response (speech-ABR) results between two ethnic groups: Malay and Chinese. In addition, it was also of interest to compare the speech-ABR outcomes obtained from the present study with the published Caucasian data. Thirty healthy male adults (15 Malay and 15 Chinese) were enrolled in this comparative study. Speech syllable/da/presented at 80 dBnHL was used to record speech-ABR waveforms from the right ear of each subject. Amplitudes and latencies of speech-ABR peaks (V, A, C, D, E, F and O), as well as composite onset measures (V/A duration, V/A amplitude and V/A slope) were computed and analyzed. When the two ethnic groups were compared, all speech-ABR results were not statistically different from each other (p > 0.05). When the data from the present study were compared with the published Caucasian data, most of the statistical analyses were significant (p < 0.05). That is, Asian subjects revealed significantly higher peak amplitudes, earlier peak latencies, higher V/A amplitudes and steeper V/A slopes than that of Caucasians. The speech-ABR results between Malay and Chinese were found to be essentially similar due to anatomical similarities. Nevertheless, specific normative data for Asian adults are required as their speech-ABR results are different from that of Caucasian males. This issue should be addressed before it can be applied holistically in multiracial countries.     

Effect of some free radical scavengers on reperfusion induced arrhythmias in the isolated rat heart

The possible role of oxygen free radicals in the development of reperfusion arrhythmias was investigated using a 10-min period of coronary ligation followed by reperfusion in the isolated rat heart. Superoxide dismutase (5 to 20 u/ml) glutathione (10(-5) to 10(3)M) and ascorbic acid (10(-4) to 5 X 10(-4) M) when given before coronary ligation attenuated the development of reperfusion arrhythmias. Mannitol (2 X 10(-2)M) and catalase (100 and 300 u/ml) did not have any significant effect on reperfusion arrhythmias when given alone but they did potentiate the antiarrhythmic effect of superoxide dismutase. Glutathione, and a combination of superoxide dismutase, catalase and mannitol also reduced the incidence of reperfusion induced ventricular fibrillation when given just before reperfusion. By perfusing hearts with ferricytochrome C it was possible to show an increased reduction of ferricytochrome C during the first minute of reperfusion which could be prevented by the addition of superoxide dismutase. These results provide evidence that oxygen free radicals are produced and may be important in the genesis of reperfusion induced arrhythmias in the isolated rat heart.     

Effect of cross-fostering on renal anti-oxidant/oxidant status and development of hypertension in spontaneously hypertensive rats

1. The hypotensive effect of cross-fostering in spontaneously hypertensive rats (SHR) is thought to involve adjustments in renal function. However, its association with renal anti-oxidant/oxidant balance during cross-fostering is not known. 2. The present study examined the effect of cross-fostering and in-fostering of 1-day-old offspring between SHR and Wistar-Kyoto (WKY) dams on renal anti-oxidant/oxidant status and systolic blood pressure (SBP). Renal anti-oxidant/oxidant status and SBP were determined in the offspring from 4-16 weeks of age. 3. Cross-fostered SHR had significantly lower SBP than in-fostered SHR at 6, 8 and 12 weeks, but not at 16 weeks (127 ± 1 vs 144 ± 2, 138 ± 1 vs 160 ± 1, 174 ± 2 vs 184 ± 2 and 199 ± 2 vs 194 ± 3 mmHg at 6, 8, 12 and 16 weeks, respectively). No differences in SBP were evident between cross-fostered and in-fostered WKY rats. There were no significant differences in levels of thiobarbituric acid-reactive substances (TBARS), protein carbonyl and total anti-oxidant status (TAS) or superoxide dismutase, catalase, glutathione peroxidase (GPx), glutathione S-transferase and glutathione reductase activity between cross-fostered and in-fostered SHR or WKY offspring. However, compared with WKY rats, catalase activity was higher at 6 and 16 weeks, TAS was higher at 16 weeks and GPx activity and TBARS were lower at 16 weeks in SHR. 4. It appears that cross-fostering of SHR offspring to WKY dams during the early postnatal period causes a transient delay in the rise in blood pressure in SHR and that this does not involve the renal anti-oxidant/oxidant system.     

Cysteinoyl- and cysteine-containing dipeptidoylbenzotriazoles with free sulfhydryl groups: easy access to N-terminal and internal cysteine peptides

N-Protected cysteines 4a-c each with a free sulfhydryl group were prepared in 70-75% yields by treatment of L-cysteine with 1-(benzyloxycarbonyl) benzotriazole (Cbz-Bt) 1a, N-(tert-butyloxy-carbonyl)benzotriazole (Boc-Bt) 1b, and 1-(9-fluorenylmethoxy-carbonyl)benzotriazole (Fmoc-Bt) 1c, respectively. N-Protected, free sulfhydryl cysteines 4a-c were then converted into the corresponding N-protected, free sulfhydryl cysteinoylbenzotriazoles 7a-c (70-85%), which on treatment with diverse amino acids and dipeptides afforded the corresponding N-protected, free sulfhydryl N-terminal cysteine dipeptides 8a-e and tripeptides 8f-h in 73-80% yields. N-Protected, free sulfhydryl cysteine-containing dipeptides 9a,b were converted into the corresponding N-protected, free sulfhydryl dipeptidoylbenzotriazoles 10a,b (69-81%), which on treatment with amino acids, dipeptides, and a tripeptide afforded internal cysteine tripeptides 11a-c, tetrapeptides 11d,e and pentapeptide 11f, each containing a N-protected, free sulfhydryl groups in 70-90% yields under mild conditions. Treatment of N-protected, free sulfhydryl cysteinoylbenzotriazole 7a with diamines 12a,b afforded directly the cysteine-containing disulfide-bridged cyclic peptides 14a,b in 50% yields.     

Optimal antiplatelet treatment for percutaneous coronary intervention: clopidogrel vs. ticlopidine

Antiplatelet treatment for patients undergoing percutaneous coronary interventions is a rapidly changing area. Thienopyridines derivatives (ticlopidine and clopidogrel) have shown to decrease major cardiovascular events. Ticlopidine can cause rare but serious side effects, especially during the first 3 months of treatment. Clopidogrel appears to be a safer alternative to ticlopidine. However, resistance to clopidogrel therapy may increases the risk of recurrent cardiovascular events. Whether increased doses of clopidogrel might overcome this resistance in nonresponsive patients warrants further investigation.     

Minimal vs median sternotomy for aortic valve replacement

The aim of this study was to compare postoperative outcomes in patients undergoing aortic valve replacement through a ministernotomy or conventional sternotomy. Sixty patients were randomized into 2 groups of 30 each: group 1 had a full sternotomy and group 2 had a ministernotomy. Pain was evaluated on a daily basis, pulmonary function tests were performed perioperatively. The skin incision was shorter in group 2 (7.17 vs 24.50 cm in group 1). There was significantly less mediastinal drainage in group 2 (233 vs 590 mL in 24 hours in group 1). Group 1 patients had more blood transfusions and longer ventilation time. In group 1, 96.7% experienced severe pain, whereas 93.3% in group 2 reported minimal pain. Hospital stay was 17.7 days in group 1 and 8.0 days in group 2. The ministernotomy had a cosmetic advantage, less blood loss and transfusion requirement, greater sternal stability, better respiratory function, and earlier extubation and hospital discharge.     

The influence of hemodynamic forces on biomarkers in the walls of elastase-induced aneurysms in rabbits

Introduction Biological and biophysical factors have been shown to play an important role in the initiation, progression, and rupture of intracranial aneurysms. The purpose of this study was to evaluate the association between hemodynamic forces and markers of vascular remodeling in elastase-induced saccular aneurysms in rabbits. Methods Elastase-induced aneurysms were created at the origin of the right common carotid artery in rabbits. Hemodynamic parameters were estimated using computational fluid dynamic simulations based on 3-D-reconstructed models of the vasculature. Expression of matrix metalloproteinases (MMPs), their inhibitors (TIMPs) and markers of vascular remodeling were measured in different spatial regions within the aneurysms. Results Altered expression of biological markers relative to controls was correlated with the locations of subnormal time-averaged wall shear stress (WSS) but not with the magnitude of pressure. In the aneurysms, WSS was low and expression of biological markers was significantly altered in a time-dependent fashion. At 2 weeks, an upregulation of active-MMP-2, downregulation of TIMP-1 and TIMP-2, and intact endothelium were found in aneurysm cavities. However, by 12 weeks, endothelial cells were absent or scattered, and levels of pro- and active-MMP-2 were not different from those in control arteries, but pro-MMP-9 and both TIMPs were upregulated. Conclusion These results reveal a strong, spatially localized correlation between diminished WSS and differential expression of biological markers of vascular remodeling in elastase-induced saccular aneurysms. The ability of the wall to function and maintain a healthy endothelium in a low shear environment appears to be significantly impaired by chronic exposure to low WSS.     

Effects of Fructus Piperis Longi extract on fibrotic liver of gamma-irradiated rats

Background  

A major biomarker for liver fibrosis is transglutaminase which catalyzes cross-linking of epsilon-amines and alpha-glutamyl residues among amino acids leading to fibrosis. Fructus Piperis Longi is a common herb used in Chinese medicine. The present study evaluates the role of the ethanol extract of Fructus Piperis Longi in the modulation of liver function in liver fibrosis.