Fluoride, triclosan and organic weak acids as modulators of the arginine deiminase system in biofilms and suspension cells of oral streptococci

Introduction:  The arginine deiminase system (ADS) of oral bacteria is a major generator of alkali (ammonia) in dental plaque and is considered to have anticaries effects. However, many of the antimicrobial agents used in oral care products may reduce alkali production by the ADS. The objective of our work was to assess the sensitivity of the ADS of oral streptococci to commonly used antimicrobials, fluoride, triclosan and organic weak acids.
Methods:  Streptococcus sanguinis NCTC 10904 and Streptococcus ratti FA-1 were grown in suspension cultures and mono-organism biofilms. ADS activity at pH values of 4, 5 and 6 was assessed, and the actions of the agents was determined in terms of reduced production of alkali from arginine, inhibition of ADS enzymes and changes in uptake of arginine.
Results:  ADS activity was not greatly affected by pH changes between 4 and 6 and was greater per unit of biomass for cell suspensions than for biofilms. NaF was a poor inhibitor, while triclosan was highly effective with a 50% inhibitory dose for the two organisms between 0.03 and 0.05 and between 0.10 and 0.15 m m -h for suspension cells and biofilms, respectively. The weak acid indomethacin was nearly as potent at pH 4.0 as triclosan, while capric and lauric acids were less potent, especially for biofilms. The methyl ester of lauric acid was slightly stimulatory. The major targets for the inhibitors appeared to be transport systems for arginine uptake, although carbamate kinase was a secondary target.
Conclusion:  Triclosan, indomethacin, caprate and laurate can reduce ADS activity in dental plaque.     

L-精氨酸和左旋-硝基精氨酸甲酯对纯化视网膜神经节细胞凋亡的影响

目的 探讨L-精氨酸(L-arginine, L-Arg)和左旋-硝基精氨酸甲酯（L-nitro-arginine-methylester, L-NAME）对纯化培养的视网膜神经节细胞(retinal gangal cells, RGCs)凋亡的影响。 方法 同化培养液培养抗体纯化的Sprague-Dawley(SD)系大鼠RGCs；在纯化培养的RGCs中分组加入体积百分浓度为1×10-6、1×10-5、1×10-4、1×10-3、1×10-2、1×10-1 mol/L的L-Arg及L-NAME，培养24 h后检测各组培养上清液中硝酸盐含量、细胞的活性；培养 48 h后检测各组细胞的凋亡及细胞中bcl-2、bax及p53 mRNA的表达。 结果 培养上清液中硝酸盐含量随着L-Arg体积百分浓度的增高而增高，随着L-NAME体积百分浓度的升高而降低。低体积百分浓度时，随着L-Arg和L-NAME体积百分浓度的增加bcl-2 mRNA表达逐渐增高，bax及p53 mRNA的表达无明显变化。而高体积百分浓度时则相反。 结论 L-Arg低体积百分浓度时能促进RGCs的生长，高体积百分浓度时则促进细胞凋亡；L-NAME对L-Arg的毒害作用则起抑制作用。 (中华眼底病杂志, 2002, 18: 137-139)     

L-精氨酸对肾性高血压心肌肥厚大鼠血浆内皮素及左心室肌原癌基因c-fosmRNA表达的影响

目的:研究L-精氨酸对肾性高血压心肌肥厚大鼠血浆内皮素及左室肌原癌基因c-fosmRNA表达的影响。方法:采用原位杂交方法检测原癌基因c-fosmRNA的表达,并用图像分析仪作半定量分析。用放射免疫法测定血浆内皮素含量。结果:经过8周治疗后,L-Arg使高血压心肌肥厚大鼠左室肌原癌基因c-fosmRNA表达显著减少(P＜0.01),并显著降低血浆内皮素含量(P＜0.01)。结论:L-Arg能降低高血压心肌肥厚大鼠血浆内皮素含量并使左室肌原癌基因c-fosmRNA的表达量减少。     

L－精氨酸在离体肺保存中的作用

目的：研究一氧化氮前体L－精氨酸（L-Arg)在离体兔肺保存中的保护作用。方法：将14只新西兰兔随机分为2组,对照组以改良的Euro-Collins(ECS)液灌注及保存供肺,实验组以L－精氨酸（3mmol/L)加入改良的ECS液中灌注及保存供肺。冷保存6h。以自体血再灌注1h后,做肺静脉血气分析（PvO2),并测定血及肺组织中一氧化 氮（NO）,超氧化物歧化酶（SOD）,脂质过氧化物（LPO）含量及肺组织的超微结构以评价肺保护的效果。结果：再灌注后,实验组比对照组血氧分压显著提高（P＜0．05）。实验组血及肺组织中NO及SOD含量较对照组高（P＜0．05）,LPO含量较对照组低（P＜0．05）,透射电镜检查实验组损伤轻于对照组,结论：肺保存不超过6h时,在改良的ECS液中加入L-Arg用于离体肺的灌注和保存,能减轻肺损伤。     

Preoperative immunonutrition in patients undergoing liver resection:A prospective randomized trial

BACKGROUND Preoperative supplementation with immunonutrients, including arginine and n-3 fatty acids, has been shown in a number of systematic reviews to reduce infectious complications in patients who have undergone gastrointestinal surgery. Limited information, however, is available on the benefits of nutritional supplementation enriched with arginine and n-3 fatty acids in patients undergoing liver resection.AIM To evaluate the effects of preoperative nutritional supplementation enriched with arginine and n-3 fatty acids on inflammatory and immunologic markers and clinical outcome in patients undergoing liver resection.METHODS Thirty-four patients undergoing liver resection were randomized to either five days of preoperative Impact? [1020 kcal/d, immunonutrition(IMN) group], or standard care [no supplementation, standard care(STD) group]. Nutritional status was measured at study entry by subjective global assessment(SGA).Functional assessments(grip strength, fatigue and performance status) were carried out at study entry, on the day prior to surgery, and on postoperative day(POD) 7 and 30. Inflammatory and immune markers were measured at study entry, on the day prior to surgery, and POD 1, 3, 5, 7, 10 and 30. Postoperative complications were recorded prospectively until POD30.RESULTS A total of 32 patients(17 IMN and 15 STD) were analysed. All except four patients were SGA class A. The plasma ratio of(eicosapentaenoic acid plus docosahexaenoic acid) to arachidonic acid was higher in IMN patients on the day prior to surgery and POD 1, 3, 5 and 7(P 0.05). Plasma interleukin(IL)-6 concentrations were elevated in the IMN group(P = 0.017 for POD7). No treatment effect was detected for functional measures, immune response(white cell count and total lymphocytes) or markers of inflammation(C-reactive protein,tumour necrosis factor-α, IL-8, IL-10). There were 10 patients with infectious complications in the IMN group and 4 in the STD group(P = 0.087). Median hospital stay was 9(range 4–49) d in the IMN group and 8(3-34) d in the STD group(P = 0.476).CONCLUSION In well-nourished patients undergoing elective liver resection, this study failed to show any benefit of preoperative immunonutrition.     

老年人急性颅脑损伤早期血浆精氨酸加压素含量变化的研究

目的研究老年人急性颅脑损伤早期血浆中精氨酸加压素（AVP）的变化及临床意义。方法用放射免疫（RIA）法检测32例老年人急性颅脑损伤早期患者,30例非颅脑损伤早期患者和30例健康老年人的血浆AVP,分析和观察其临床变化。结果32例老年人急性颅脑损伤早期组血浆AVP［（48．30±8．28）ng／人］明显高于非颅脑损伤早期组［（25．56±4．64）ng／L］,P＜0.01;非颅脑损伤早期组高于老年健康组［（5.06±4.12）ng／L］,P＜0．01。其中老年人急性颅脑损伤早期组中GCS评分与AVP呈负性相关,P＜0.01;而非颅脑损伤的早期组与GCS评分无明显意义,P＞0．05。结论AVP参与了各种急性损伤早期的病理生理过程,但急性颅脑损伤早期组明显高于非颅脑损伤早期组,尤其颅脑损伤早期组中GCS评分＞8分明显高于＜8分组,颅脑损伤越严重,AVP越高,提示AVP可作为观察老年人,颅脑损伤早期严重程度的标志之一,对临床抢救具有指导意义。     

Urinary ET-1, AVP and sodium in premature infants treated with indomethacin and ibuprofen for patent ductus arteriosus

The relative potency and interrelationship between vasoactive and natriuretic mediators are thought to be important in the transition from fetal to neonatal life. The relationship between urinary vasoactive factors and sodium excretion has not been adequately addressed in premature infants receiving indomethacin and ibuprofen for therapy of patent ductus arteriosus. Excretion rates of AVP, ET-1 and sodium were measured in premature infants with RDS receiving indomethacin or ibuprofen. Forty-four RDS premature infants (<34-week gestation) with PDA received either ibuprofen (n=22) in an initial dose of 10 mg/kg followed by two doses of 5 mg/kg each after 24 and 48 h or 3 doses at 12-h intervals of indomethacin (n=24), 0.2 mg/kg, infused continuously over a period of 15 min. Urinary ET-1, AVP and sodium excretion were measured before and after treatment. Indomethacin treatment caused a significant decrease in urinary ET-1 and AVP excretion (UET-1/Ucr 0.14±0.01 vs. 0.10±0.05 fenton/mmol; P<0.05; 24.42±6.18 vs. 12.63±3.06 pg/mmol; P<0.05, respectively), along with a significant reduction in urinary sodium (92.1±36.1 vs. 64.8±35.6 mmol/l; P<0.01), fractional excretion of sodium (6.8±37.1 vs. 4.5±37.1%; P<0.01) and urinary osmolality (276.2±103.9 vs. 226.4±60.3 mOsmol/kg; P<0.05). Ibuprofen treatment caused a significant decrease in urinary AVP (UAVP/Ucr 24.5±3.4 vs. 16.3±2.04 pg/mmol; P<0.01), along with a significant decrease in urinary sodium (78.0±8.4 vs. 57.0±8.0 mmol/l; P<0.05) and in fractional excretion of sodium (7.5±1.3 vs. 3.9±3.0%; P<0.05), while it did not modify urinary ET-1 excretion. The association of renal ET-1 and AVP activity with sodium excretion in premature infants treated with indomethacin and ibuprofen supports the hypothesis that these factors may play a role in the physiologic changes in sodium excretion.