Expression of Na+/HCO3− co‐transporter proteins (NBCs) in rat and human skeletal muscle

Aim: Sodium/bicarbonate co‐transport (NBC) has been suggested to have a role in muscle pH regulation. We investigated the presence of NBC proteins in rat and human muscle samples and the fibre type distribution of the identified NBCs. Methods and results: Western blotting of muscle homogenates and sarcolemmal membranes (sarcolemmal giant vesicles) were used to screen for the presence of NBCs. Immunohistochemistry was used for the subcellular localization. The functional test revealed that approximately half of the pH recovery in sarcolemmal vesicles produced from rat muscle is mediated by bicarbonate‐dependent transport. This indicates that the NBCs are preserved in the vesicles. The western blotting experiments demonstrated the existence of at least two NBC proteins in skeletal muscle. One NBC protein (approximately 150 kDa) seems to be related to the kidney/pancreas/heart isoform NBC1, whereas the other protein (approximately 200 kDa) is related to the NBC4 isoform. The two NBC proteins represent the electrogenic isoforms named NBCe1 and NBCe2. Membrane fractionation and immunofluorescence techniques confirmed that the two NBCs are located in the sarcolemmal membrane as well as in some internal membranes, probably the T‐tubules. The two NBCs localized in muscle have distinct fibre type distributions. Conclusions: Skeletal muscle possesses two variants of the sodium/bicarbonate co‐transporter (NBC) isoforms, which have been called NBCe1 and NBCe2.     

Sodium renal imaging in mice at high magnetic fields.

This work presents the first sodium MRI functional renal study on a mouse model. The tissue sodium concentration was monitored during induced diuresis with furosemide. By using density-weighted chemical shift imaging (DWCSI) at high field strength a temporal resolution of less than 5 min for three dimensional (3D) data sets with high spatial resolution was achieved. A maximum increase of 20% in the cortex and a decrease of 45% of the original signal strength in the medulla were observed. These findings correspond well with experiments conducted on much larger rodent models.     

Distal radial fractures Injectable calcium phosphate bone cement versus conventional treatment

AMEDLINEsearchwasconductedtoidentifystudiespublishedfromJanuary1999toMarch2004thatcom-paredinjectablecalciumphosphatebone(NorianSRS)cementwithconventionaltreatmentindistalradialfrac-tures.Fromalistof13articlesidentifiedfromthesearchstrategy,fourarticleswe…     

透明质酸钠预防粘连性肠梗阻术后再粘连临床观察

Objective To investigate the prevention of intestines adhesion about sodium hyaluronic acid in postoperative intestines adhesion.Methods Eighteen cases of adhesive intestine obstruction were done intestinal release or bowel resection.2～4mL sodium hyaluronic acid was put to the wound,anastigmatic and rough surface of peritoneal.Gastrointestinal decompression,anti-infective and infusion were taken after oper-ations.Followed up 8～24 months.Results Obstructive symptoms haven't happened,the effective rate is 100%.Only 2 cases have intermittent abdominal pain without obstruction,the incidence was 11%.Conclu-sion Sodium hylauronic acid is effective to prevent the adhesion of postoperative intestines adhesion,simp-ler use,fewer side-effects and great value to appliance.     

高容血液稀释联合术中控制性降压对腰椎手术病人心率变异性的影响

目的:探讨术前急性高容血液稀释联合术中硝普钠控制性降压对腰椎手术病人心率变异性(HRV)的影响.方法:15例腰椎骨折椎板减压、切复内固定病人,术前输入6%羟乙基淀粉20ml/kg和乳酸林格氏液20ml/kg以实施急性高容血液稀释,术中采用硝普钠微泵输注实施控制性降压,输注速度为0.5～6μg·kg-1·min-1,控制平均压(MAP)在55～65mmHg之间.观察插管后稀释前(T0)、稀释后降压前(T1)、降压后10min(T2)、30min(T3)和停降压后10min(T4)和30min(T5)6个时间点总功率谱(TP)、低频值(LF)、高频值(HF)、LF/HF、标化低频值(Lfnrom)和标化高频值(Hfnorm).结果:以上6个时间点TP、LF、HF、LF/HF、Lfnrom和Hfnorm均无显著变化.结论:术前急性高容血液稀释联合术中控制性降压时心脏自主神经功能稳定.     

丙泊酚、硫喷妥钠联合麻醉诱导对血液动力学的影响

目的：观察小剂量丙泊酚和硫喷妥钠联合用于麻醉诱导对血流动力学的影响及临床应用价值。方法：择期全身麻醉气管插管手术患者84例，ASAⅠ-Ⅱ级，随机分成3组（n=28），硫喷妥钠组（A组）：诱导量5mg/kg；丙泊酚组（B组）；诱导量2.0mg/kg；联合诱导组（C组）硫喷妥钠1－2mg/kg加丙泊酚0.5-1.0mg/kg，观察诱导后2min,5min,10min血液动力学变化。结果：C组在丙泊酚诱导前先静脉预注硫喷妥钠1－2mg/kg，患者静脉注射部位疼痛发生率明显低于B组（P＜0．01），平均动脉压和心率均无明显变化（P＞0．05），而A和B组给药后2min与5min平均动脉压均低于麻醉前，心率均高于麻醉前（P＜0．05－P＜0．05）。结论：丙泊酚与硫喷妥钠联合麻醉诱导具有协同作用，减少单独用药不良反应发生率，血液动力学稳定，麻醉诱导更加平稳，安全，为临床全麻诱导提供一种可行的方法。     

Inhibition of the amorphous calcium phosphate phase transformation reaction by polyphosphates and metal ions

Summary The induction time for amorphous calcium phosphate (ACP) phase transformation was monitored at pH 7.4 and T=25°C with [Ca²⁺]₀=[PO₄]₀=4.0×10⁻³ M, as a function of added crystal growth inhibitors Mg²⁺, Sr²⁺, Zn²⁺, pyrophosphate (PP), and tripolyphosphate (TPP). Metal ions increase the induction time for the initiation of the phase change reaction in the order Zn²⁺<Sr²⁺<Mg²⁺. For polyphosphates it was observed that both PP and TPP are potent inhibitors with TPP more effective than PP as expected. The combination of Mg²⁺ or Sr²⁺ and PP or TPP leads to a synergistic delay in the onset of the phase conversion. The greatest inhibition was observed for Mg²⁺ and TPP. Reaction solutions containing 2.0×10⁻⁴ M Mg²⁺ and 4.0×10⁻⁵ M TPP resulted in a 90% increase in the induction time over what would be anticipated from an additive effect from these species.     

AN-132 block of cardiac sodium channels: A gate-related receptor analysis

Summary Based on the gate-related receptor hypothesis, an analysis of kinetics of AN-132, a new antiarrhythmic agent, blockade of cardiac sodium channels and the gate-related receptor which is bound by the drug was performed by computer simulation. Model-predicted apparent rates of onset of AN-132 (30 μmol/L) blocking were 0.051, 0.038, and 0.034 AF⁻¹ at stimulation frequencies of 1.0, 2.0 and 3.0 Hz, respectively. The time constant of recovery from block by AN-132 at resting potential -90 mV was 39.5 s. These findings are in agreement with those experimental data documented. The analysis of gate-related receptor shows that AN-132 binds the inactivation gate-related receptor, and the binding and unbinding are modulated by the inactivation process.     

Differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive and tetrodotoxin-resistant single sodium channels

The differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) single sodium channel currents in rat dorsal root ganglion (DRG) neurons were investigated using the outside-out configuration of patch-clamp technique. Channel conductances were 10.7 and 6.3 pS for TTX-S and TTX-R sodium channels, respectively, at a room temperature of 24–26°C. The single-channel current of TTX-S sodium channels at the test potential of −30 mV was −1.27 ± 0.25 pA, and was not changed after exposure to 10 μM tetramethrin (−1.28 ± 0.23 pA). The open time histogram of TTX-S single-channel currents could be fitted by a single exponential function with a time constant of 1.27 ms. After exposure to 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 1.36 ms (τ_fast) and 5.73 ms (τ_low). The percentage of contribution of each component to the population was 62% for the fast component representing the normal channels and 38% for the slow component representing the tetramethrin modified channels. The amplitudc of TTX-R single-channel currents was slightly changed from −0.72 ± 0.14 to −0.83 ± 0.07 pA by 10 μM tetramethrin. The open time histogram of TTX-R single-channel currents could be fitted by a single exponential function with a time constant of 1.92 ms. In the presence of 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 2.07 ms (τ_fast) and 9.75 ms (τ_slow). The percentage of contribution of each component was 15% for the fast, unmodified component and 85% for the slow, modified component. Differential effects of tetramethrin on the open time distribution of single sodium channel currents explains the differential sensitivity of TTX-S and TTX-R sodium channels.     

Characteristics of antibody responses induced in mice by protein allergens

Whereas many foreign proteins are immunogenic, only a proportion is also allergenic, having the capacity to induce the quality of immune response necessary to support the production of IgE antibody. We have demonstrated previously that intraperitoneal administration to mice of proteins such as ovalbumin (OVA) or the industrial enzyme A. oryzae lipase, which possess significant allergenic potential, stimulates the production of both IgG and IgE antibody. Identical exposure to bovine serum albumin (BSA), a protein with limited potential to cause immediate respiratory or gastrointestinal hypersensitivity reactions, induced IgG responses only. In the current investigations, the quality of immune responses induced following exposure to these proteins via mucosal tissue (intranasal) has been compared with those provoked following administration via a non-mucosal (intraperitoneal) route of exposure. Intranasal or intraperitoneal administration of BSA, OVA or A. oryzae lipase elicited in each case vigorous IgG and IgG1 antibody responses. For all three proteins, at every concentration tested, and via both routes of exposure, IgG1 antibody titres paralleled closely IgG titres. However, the three materials displayed a differential potential to provoke IgE responses and this correlated with their known allergenic potential in humans. Thus, OVA and A. oryzae lipase stimulated strong IgE antibody responses, whereas BSA provoked low titre IgE only at the highest concentration tested (5% administered intraperitoneally). The quality of induced responses was not affected by the route of exposure. It would appear, therefore, that the stimulation of IgG and IgG1 antibody responses is a reflection of protein immunogenicity whereas protein allergenicity is associated with the induction of strong IgE responses.