运动性与高血压性心肌肥大时心源性活性肽变化比较

为进一步探讨运动性心肌肥大形成的自分泌和旁分泌机制,本实验采用放射免疫方法比较了运动性和高血压性肥大心脏心肌局部和血浆多种心源性活性肽变化。与正常对照大鼠相比,游泳运动10周大鼠,左心重/体重(心系数)提高25%(P<0.01),心肌局部血管紧张素Ⅱ(AngiotensinⅡ,AngⅡ)、内皮素(endothelin,ET)和心钠素(atrial natriuretic factor, ANF)含量分别提高197%、44%和23%(P<0.05),血浆AngⅡ、ET和ANF含量分别提高41％、67％和19％（P<0.05）。与自发性高血压大鼠（Spontaneously hy pertensive rat,SHR）相比,运动大鼠心肌AngⅡ、ET和ANF分别降低64％、84％和105％（P<0.05）,血浆AngⅡ、ET和ANF分别降低26％、45％和45％（P<0.05）。结果表明运动肥大心脏心源性活性肽变化特征与高血压肥大心脏不同。这些不同变化是否对运动性心肌肥大调节具有意义值得进一步研究。     

运动性心肌肥大大鼠心肌肌肉生长抑制素表达的变化

目的:观察运动性心肌肥大大鼠心肌组织肌肉生长抑制素(myostatin,MSTN)表达的变化。方法:16周龄雄性SD大鼠随机分为对照组和运动组,每组10只。运动组进行持续8周跑台训练,每周5次,每次60分钟,跑速26米/分钟。测定两组大鼠心重并计算心系数,HE染色观察心肌细胞横截面积,分别采用real-time PCR技术和western blot方法测定心肌MSTN mRNA和蛋白表达,放免法测定血浆MSTN水平。结果:运动组大鼠心脏重量和心系数显著高于对照组(P<0.05),心肌细胞横截面积增大。运动组大鼠血浆MSTN水平、心肌MSTN mRNA和蛋白表达显著低于对照组(P<0.05)。结论:运动性心肌肥大时,大鼠心肌MSTN mRNA和蛋白表达被抑制,可能通过解除其对心肌生长的负调控作用,促进心肌细胞对运动产生适应性肥大。     

运动训练诱导自发性高血压大鼠生理性心脏肥大

 目的 观察规律运动训练对自发性高血压大鼠(SHR)心脏肥大的影响,探讨运动发挥心脏保护效应的可能机制。方法 30只SHR随机分为高血压运动组(SHR-Ex)和高血压对照组(SHR-C),15只健康Wistar大鼠作为正常血压对照组(NC)。SHR-Ex组大鼠进行8周游泳运动(每天60 min,5 d/周),SHR-C组和NC组在鼠笼内安静饲养。实验后,利用智能无创血压测试仪测量尾动脉血压,超声心动图监测心脏结构与功能,分离左心室并称重,HE和Masson染色分别获取心肌细胞横截面积(CSA)和胶原容积分数(CVF),Western Blot检测胚胎基因和心脏肥大信号途径蛋白表达量。结果 实验过程中,由于拒跑、死亡等原因共剔除7只大鼠,最终纳入38只,其中NC组15只、SHR-C组12只和SHR-Ex组11只。与NC组比较,SHR-C组大鼠出现向心性心脏肥大,心肌纤维化(CVF升高,P<0.05),心钠素(ANF)、肌球蛋白轻链-2(MLC-2)、钙调神经磷酸酶Aβ亚基(CNAβ)、PI3激酶p110α亚基[PI3-K(p110α)]和磷酸化Akt(p-Akt)蛋白表达量上调(P<0.05);与SHR-C组比较,SHR-Ex组发生离心性心脏肥大,心肌纤维化减轻(CVF下降,P<0.05),心功能增强(P<0.05),ANF、MLC-2和CNAβ蛋白表达量下调(P<0.05),PI3-K(p110α)和p-Akt的变化无统计学意义。结论 长期运动训练能够促进SHR由病理性心脏肥大向生理性心脏肥大转变,其机制可能与钙调神经磷酸酶信号途径活性下降有关。     

运动性和高血压性肥大心脏心肌细胞超微结构的对比研究

为了研究运动性和高血压性肥大心脏心肌细胞的本质差别 ,用透射电子显微镜观察了运动性和高血压性大鼠肥大心肌细胞的超微结构。结果表明 :①高血压大鼠和运动大鼠心肌细胞肌膜、肌浆网、T管、线粒体、细胞核、闰盘等发生了不同程度的病变 ,而对照大鼠则未见异常。②高血压大鼠心肌的线粒体嵴结构、细胞核、闰盘及心肌纤维的明暗带方面的病变较重 ;而运动组肌膜下水肿、纤维间水肿较明显。本结果提示 :高血压性和运动性心肌肥大均存在超微结构的病理变化 ,高血压大鼠心肌细胞内蛋白质合成和能量代谢功能受损严重 ,运动大鼠心肌细胞水盐代谢有明显障碍。     

运动对自发性高血压大鼠心肌血管内皮生长因子及其基因表达的影响

为探讨血管内皮生长因子（Ｖａｓｃｕｌａｒ　ｅｎｄｏｔｈｅｌｉａｌ　ｇｒｏｗｔｈ　ｆａｃｔｏｒ,ＶＥＧＦ）是否参与运动改善高血压性心肌肥大机制,采用免疫组化和分子杂交方法,研究了自发性高血压大鼠（ｓｐｏｎｔａｎｅｏｕｓｌｙ　ｈｙｐｅｒｔｅｎｓｉｖｅ　ｒａｔｓ,ＳＨＲ）游泳运动后心肌细胞ＶＧＥＦ及其基因表达的改变。免疫组化结果表明,ＳＨＲ经１０周游泳后,心肌细胞浆内ＶＥＧＦ特异染色颗粒比安静ＳＨＲ明显增多。Ｎｏｒｔｈｅｍ分子杂交结果表明,ＳＨＲ运动后心肌ＶＥＧＦ　ｍＲＮＡ表达比安静ＳＨＲ降低。目前对这一结果的生理意义还不清楚,推测可能与改善高血压肥大心肌间质血管增生机制有关。     

运动诱导的大鼠心肌细胞HSP72 mRNA表达与超微结构改变

目的 :研究运动诱导的大鼠心肌细胞HSP72mRNA表达与大鼠心肌细胞超微结构改变的可能关系。方法 :将 36只SD大鼠随机分为安静对照组 (C)、1周运动组 (T1)、2周运动组 (T2 )和3周运动组 (T3)。安静对照组不运动 ,T1组、T2组和T3组以 75 %VO2 max强度进行跑台运动 ,分别运动 1周、2周、3周 ,每周运动 6天 ,每天 1小时。在末次运动结束后 2 4小时以RT -PCR法检测大鼠心肌细胞热休克蛋白 72mRNA的表达 ;以常规电镜检测观察大鼠心肌细胞超微结构的变化。结果 :①T1和T2组HSP72mRNA表达明显多于C组和T3组。②以C组心肌细胞电镜表现为正常 ,则各组大鼠电镜表现的心肌损伤程度为T1组 >T2组 >T3组。结果提示 :运动不同时期造成心肌损伤程度不同的原因可能与运动后心肌细胞HSP72mRNA表达量不同有关。HSP72mRNA表达可能为运动后心肌保护的分子机理。     

运动性心肌肥大大鼠背根神经节降钙素基因相关肽基因表达的变化

目的:探讨运动性心肌肥大大鼠背根神经节降钙素基因相关肽基因表达的变化。方法:雄性SD大鼠随机分为对照组(n=33)和耐力训练组(n=33)。耐力训练组进行10周的跑台耐力训练,建立运动性心肌肥大模型。建模后48h,从两组随机抽取17只大鼠,连续3天进行力竭运动,最后一次力竭运动后即刻处死全部实验动物。记录力竭运动距离和大鼠体重,取大鼠心脏和腰段背根神经节,记录心脏湿重,采用荧光定量聚合酶链式反应技术测定大鼠背根神经节降钙素基因相关肽mRNA的表达量。结果:10周后,耐力训练组大鼠心脏重量与体重之比和力竭运动距离显著高于对照组(P<0.01)。与对照组比较,力竭运动前耐力训练组背根神经节CGRPmRNA表达显著下降(P<0.01),力竭运动后耐力训练组背根神经节CGRPmRNA表达与力竭运动前相比无明显变化,而对照组较力竭运动前显著下降(P<0.01)。结论:运动性心肌肥大大鼠背根神经节CGRP基因表达下调,力竭运动后表达保持稳定。     

运动诱导的大鼠心肌细胞HSP72 mRNA表达与血清心肌酶活性和心肌力学指标的变化

目的:探讨运动诱导表达的热休克蛋白72(HSP72) mRNA与大鼠血清心肌酶活性和心肌力学指标之间的关系.方法:将36只SD大鼠随机平均分为安静对照组(C)、1周运动组(T1)、2周运动组(T2)和3周运动组(T3).安静对照组不运动,T1组、T2组和T3组分别以75%VO2max强度进行1周、2周、3周跑台运动,每周训练6天,每天1小时.在末次运动结束后24小时分别以RT-PCR法检测大鼠心肌细胞HSP72mRNA的表达,以MPA-IV型多道生物信号分析系统同步记录心肌力学参数,以酶法检测血清心肌酶活性.结果:(1)T1和T2组心肌细胞HSP72 mRNA表达明显高于C组和T3组.(2)T1组大鼠血清CK、CK-MB和AST活性较C组明显升高;且随运动周期的延长,其均值逐渐降低.(3)运动1周后LVSP、dp/dt max 和dp/dt min较C组均有下降,而LVEDP也稍减少,但无统计学意义(P>0.05);随运动周期的延长,其均值逐渐恢复至对照组水平.结果提示运动后心肌细胞的保护作用可能与心肌细胞HSP72 mRNA表达有内在关系.     

Pulse radiolysis of the DNA-binding bisbenzimidazole derivatives Hoechst 33258 and 33342 in aqueous solutions

PURPOSE: The DNA-minor-groove-ligands bisbenzimidazoles Hoechst 33258 and 33342 have been reported to protect against radiation-induced DNA-strand breakage. In order to elucidate the mechanisms of protection by these DNA-binding compounds, pulse radiolysis studies on the reactions of the OH radical, the solvated electron and the H atom with Hoechst as well as OH-radical-induced nucleotide radical quenching by free Hoechst (model level) was investigated. MATERIALS AND METHODS: The pulse radiolysis of Hoechst 33258 and 33342 was studied in N2O and N2O/O2-(4:1)-saturated aqueous solutions in the absence and presence of azide and bromide ions and nucleotides. RESULTS: In a fully scavenged system (3 x 10(-2) mol x dm(-3) t-butanol, N2O/O2-saturated), a transient is formed which in the presence of phosphate buffer is no longer observed. This is assigned metastable quinonoid forms of Hoechst (lambdamax(Hoechst) = 340; lambdamax(transient) = 370 nm) which is generated in protonation/ deprotonation reactions by H+/OH- formed during the pulse. To prevent their formation 10(-3) mol x dm(-3) phosphate buffer was added in all other experiments. The transient spectra formed upon OH-radical attack (k=9 x 10(9) dm3 x mol(-1) x s(-1)) indicate that a major part of the primary OH-adduct radicals undergo rapid transformation (k approximately 5 x 10(5) x s(-1)), attributed to water elimination yielding an N-centered radical. This intermediate, also generated by N3. (k = 4 x 10(9) dm3 mol(-1) x s(-1)), subsequently complexes with a Hoechst molecule [k = 8 x 10(8) dm3 x mol(-1) x s(-1) epsilon(440 nm) = 1.4 x 10(4) dm3 mol(-1) x cm(-1)]. The N-centered radical does not react with O2 (k < 5 x 10(5) dm3 mol(-1) x s(-1)), but reacts readily with the superoxide radical (k= 1.0 x 10(9) dm3 x mol(-1) x s(-1)). Hoechst reacts with the peroxyl radicals derived from uridine (k approximately 5 x 10(6) dm3 x mol(-1) x s(-1)) or 5'-UMP (k approximately 1 x 10(7) dm3 mol(-1) x (s-1)), but not with the less oxidizing (e.g. methylperoxyl radical) yielding intermediates whose spectral properties are similar to those of the N-centered radical. However, they decay at a much lower rate (2k approximately 1 x 10(8) dm3 mol(-1) x s(-1)) than the N-centered radicals generated by N3. (2k= 1.1 x 10(9) dm3 x mol(-1) s(-1)), and it has been suggested that these peroxyl radicals form adducts rather than undergoing electron transfer. The H atom (k= 7 x 10(9) dm3 x mol(-1) x s(-1)) and the solvated electron (k= 2.3 x 10(10) dm3 x mol(-1) x s(-1)) yield, albeit noticeably different, H-adduct radicals which also strongly absorb in the 440 nm region. The reduction potential of Hoechst 33258 has been determined electrochemically at 0.84-0.90 V vs. NHE at pH 6.8. CONCLUSION: Hoechst reacts fast only with strongly oxidizing radicals by electron transfer (e.g. with the adenine-and guanine-derived heteroatom-centered radicals), but also more slowly with nucleo-base-derived peroxyl radicals, here albeit via addition. This may have important implications with regard to its protection owing to DNA-radical quenching under oxic vs. anoxic conditions.     

Superoxide radical reactions in aqueous solutions of pyrogallol and n-propyl gallate: the involvement of phenoxyl radicals. A pulse radiolysis study

The reactions of O2-. in aqueous solutions of pyrogallol 1 and the antioxidant n-propyl gallate 2 have been studied. In both cases the initial reaction gives hydrogen peroxide and the corresponding phenoxyl radical (k(1 + O2-.) = 3.4 x 10(5), k(2 + O2-.) = 2.6 x 10(5) dm3 mol-1S-1). These phenoxyl radicals have been produced independently by reacting 1 and 2 with Br2-. and their spectra and first pKa values measured (pKa(phenoxyl radical from 1) = 5.1, pKa(phenoxyl radical from 2) = 4.1). It is necessary to correct the observed spectra for the contribution of the H-adducts, formed by the reaction of radiolytically produced H atoms with the substrates (k(1 + H) = 2.5 x 10(9), k(2 + H) = 3.8 x 10(9) dm3 mol-1 S-1). The H-adduct spectra are given. In the reactions of O2-. with the substrates the initial transient absorbances are characteristic of the phenoxyl radicals; however at longer times a new transient absorbing around 500 nm (epsilon congruent to 10(4) dm3 mol-1 cm-1) appears. This is believed to be the deprotonated hydroxy-orthoquinone, formed by the reaction of phenoxyl radicals with O2-. (k congruent to 1.5 x 10(8) dm3 mol-1 S-1, from kinetic curve-fitting). The absorbance due to the hydroxy-orthoquinones decays by first-order kinetics (1.6 x 10(2) in the case of 1 and 1.1 x 10(2) s-1 in the case of 2). This is thought to be mainly the result of the conversion of the hydroxy-orthoquinone into its hydrate. Similar experiments were carried out with catechol and ethyl protocatechuate. The chemistry appears to be similar to that of the pyrogallol derivatives. The rate constant for reaction of these compounds with O2-. is, however, only less than or equal to x 10(4) dm3 mol-1 s-1.     

Pulse radiolysis of the DNA-binding bisbenzimidazole derivatives Hoechst 33258 and 33342 in aqueous solutions

Purpose : The DNA-minor-groove-ligands bisbenzimidazoles Hoechst 33258 and 33342 have been reported to protect against radiation-induced DNA-strand breakage. In order to elucidate the mechanisms of protection by these DNA-binding compounds, pulse radiolysis studies on the reactions of the OH radical, the solvated electron and the H atom with Hoechst as well as OH-radical-induced nucleotide-radical quenching by free Hoechst (model level) was investigated. Materials and methods : The pulse radiolysis of Hoechst 33258 and 33342 was studied in N 2 O and N 2 O/O-(4:1)-saturated aqueous solutions in the absence and presence of azide and bromide ions and nucleotides. Results : In a fully scavenged system (3 x 10 -2 mol dm -3 t -butanol, N 2 O/O-saturated), a transient is formed which in the presence of phosphate buffer is no longer observed. This is assigned metastable quinonoid forms of Hoechst (lambda; max (Hoechst) = 340; λmax (transient) = 370nm) which is generated in protonation/ deprotonation reactions by H + /OH formed during the pulse. To prevent their formation 10 3 mol dm -3 phosphate buffer was added in all other experiments. The transient spectra formed upon OH-radical attack (k = 9 x 10 9 dm 3 mol -1 s -1) indicate that a major part of the primary OH-adduct radicals undergo rapid transformation (k ≈10 5 s -1) , attributed to water elimination yielding an N -centered radical. This intermediate, also generated by N 3 * (k = 4 x 10 9 dm 3 mol -1 s -1) , subsequently complexes with a Hoechst molecule [ k = 8 x 10 8 dm 3 mol -1 s -1 ; epsilon(440 nm)=1.4 x 10 4 dm 3 mol -1 cm -1 ]. The N -centered radical does not react with O 2 (k < 5 x 10 5 dm 3 mol -1 s -1) , but reacts readily with the superoxide radical (k = 1.0 x 10 9 dm 3 mol -1 s -1) . Hoechst reacts with the peroxyl radicals derived from uridine (k ≈10 6 dm 3 mol -1 s -1) or 5'-UMP (k ≈10 7 dm 3 mol -1 s -1) , but not with the less oxidizing (e.g. methylperoxyl radical) yielding intermediates whose spectral properties are similar to those of the N -centered radical. However, they decay at a much lower rate (2 k ≈10 8 dm 3 mol -1 s -1) than the N -centered radicals generated by N 3 (2 k =1.1 x 10 9 dm 3 mol -1 s -1) , and it has been suggested that these peroxyl radicals form adducts rather than undergoing electron transfer. The H atom (k = 7 x 10 9 dm 3 mol -1 s -1) and the solvated electron (k = 2.3 x 10 10 dm 3 mol -1 s -1) yield, albeit noticeably diÚerent, H-adduct radicals which also strongly absorb in the 440nm region. The reduction potential of Hoechst 33258 has been determined electrochemically at 0.84–0.90V vs. NHE at pH 6.8. Conclusion : Hoechst reacts fast only with strongly oxidizing radicals by electron transfer (e.g. with the adenine-and guanine-derived heteroatom-centered radicals), but also more slowly with nucleobase-derived peroxyl radicals, here albeit via addition. This may have important implications with regard to its protection owing to DNA-radical quenching under oxic vs. anoxic conditions.     

Comparison of dosimetry and image quality in computed and conventional tomography.

Comparison was made of tomograms of a phantom head and a normal adult cadaver head on GE CT/T, Delta 50, EMI 5005, and CGR Stratomatic units. Image quality was ranked as follows: First, GE CT/T 8800 system; second, EMI; third, GE CT/T 7800 and Delta. The GE CT/T 7800 imaged 3.7 line pairs at high contrast with an exposure to the head phantom of 2.5 R (6.5 X 10(-4) C kg-1). The EMI exposure level was 5 R (13 X 10(-4) C kg-1) in the fast mode and 12 R (31 X 10(-4) C kg-1) in the slow mode, while the Delta 50 exposure level was fixed at 2 R (5.2 X 10(-4) C kg-1). The GE CT/T 8800 could image 6.1 line pairs/cm in a high-contrast phantom with exposures as low as 100 mR (25.8 muC/kg) but a typical operating exposure would be about 1--2 R (2.58 -5.2 X 10 (-4) C kg-1). Dosimetry ranged from 1.1 to 5.5 R/scan section (2.8--14.2 x 10(-4) C kg-1) in the CT units but never increased by a factor of more than 2, irrespective of the number of sections scanned. In conventional tomography, however, exposure increased almost arithmetically with the number of contiguous sections scanned.     

Prediction of endurance running performance for middle-aged and older runners.

The purpose of this study was to develop regression equations that would sufficiently predict the endurance running performance (ERP) of middle-aged and older runners (n = 55, 43-79 years). Among many independent variables which were selected as possible predictors of the ERP, oxygen uptake corresponding to the lactate threshold (VO2@LT), or age was found to be the single best predictor. Some variables representing training habits correlated significantly but only moderately with the ERP. Linear multiple regression equations developed in this study were: V5km = 4.203 + 0.054X1 - 0.028X2 (r = 0.87) V5km = 4.436 + 0.045X1 - 0.033X2 + 0.005X3 (r = 0.89) V10km = 4.252 + 0.042X1 - 0.026X2 (r = 0.79) V10km = 4.371 + 0.037X1 - 0.031X2 + 0.005X3 (r = 0.82) VM = 3.207 + 0.048X1 - 0.022X2 (r = 0.91) VM = 3.707 + 0.038X1 - 0.031X2 + 0.005X3 (r = 0.93) where V5km, V10km and VM are the mean running velocity at 5 km, 10 km and marathon races, respectively, and X1 = VO2@LT (ml kg-1 min-1), X2 = age (year), and X3 = average running duration per workout (min). We suggest that the ERP of middle-aged and older runners can be predicted from a linear combination of VO2@LT and age or a combination of these variables plus average running duration per workout.     

Multiple sclerosis: comparison of trace apparent diffusion coefficients with MR enhancement pattern of lesions

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging and the trace apparent diffusion coefficient (ADC) provide important structural information about tissues. The purpose of this study was to investigate the relationship between trace ADC values and the enhancement pattern of multiple sclerosis (MS) lesions. METHODS: Ninety-six lesions, identified in 24 patients with MS, were characterized by their enhancement pattern on contrast-enhanced T1-weighted MR images. There were 57 nonenhancing lesions (NELs), 28 homogeneously enhancing lesions (HELs), and 11 ring-enhancing lesions (RELs). The trace ADC means for each type of lesion and for normal-appearing white matter (NAWM) were calculated and compared using Student's t-test. RESULTS: The mean trace ADC values for HELs (mean, 7.7 x 1(-10) m2s(-1); SD, 1.4 x 10(-10) m2s(-1)) were less than those for RELs (mean, 1.2 x 10(-9) m2s(-1); SD, 3.5 x 10(-10)m2s(-1)) and NELs (mean, 1.3 x 10(-9) m2(s-1); SD, 2.6 x 10(-10) m2(s-1)). There was a significant difference between the mean trace ADC values of HELs and RELs as well as between those for HELs and NELs. There was also a significant difference in the mean trace ADC values between all lesion types and NAWM (mean, 6.9 x 10(-10) m2s(-1); SD, 5.0 x 10(-11) m2s(-1)). CONCLUSION: We found a predictable relationship between mean trace ADC and the pattern of enhancement in MS lesions, corresponding to reported histopathologic differences in myelination between lesion types and magnetization transfer ratios.     

Synthesis and relaxometry of high-generation (G = 5, 7, 9, and 10) PAMAM dendrimer-DOTA-gadolinium chelates

A series of high-generation (G) ethylenediamine-core polyamidoamine (PAMAM) dendrimers corresponding to G = 5, 7, 9, and 10 were conjugated with the bifunctional chelate 2-(4-isothiocyanatobenzyl)- 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetate (p-SCN-Bz-DOTA). Gadolinium (III) ion was added to the macromolecules, and the 1/T1 and 1/T2 NMRD profiles were measured at 3 degrees, 23 degrees, and 37 degrees C. The synthesis resulted in preparations that ranged from an average of 127 chelates and 96 Gd3+ ions per G = 5 dendrimer to an average of 3727 chelates and 1860 Gd3+ ions per G = 10 dendrimer. At 20 MHz and 23 degrees C, the 1/T1 ion relaxivity increased from 30 mM(-1) s(-1) for the G = 5 to 35 mM(-1) s(-1) for the G = 7 PAMAM dendrimer-DOTA-Gd, reaching a plateau at 36 mM(-1) s(-1) for the G = 9 and G = 10 dendrimers. A similar plateau was observed for 1/T2 with values of 36 mM(-1) s(-1) for G = 5, 42 mM(-1) s(-1) for G = 7, and 45 mM(-1) s(-1) for the G = 9 and G = 10 dendrimers. This "saturation" of ion relaxivity for high-generation dendrimers occurred over the entire frequency range studied. The 1/T1 and 1/T2 relaxivities decreased as the temperature decreased for each generation of dendrimer studied, implying that slow water exchange of bound water molecules with the bulk solvent limits the relaxivity. In such circumstances, increases in the rotational correlation time of the macromolecules associated with higher generations of dendrimer does not result in significant increases in the ion relaxivity. Although the ion relaxivity does not increase, the total molecular relaxivities increased from 2880 mM(-1) s(-1) to 66960 mM(-1) s(-1) for the G = 5 to the G = 10 dendrimer. The current findings are relevant for the design of high-generation dendrimer-based receptor agents.     

Diffusion-weighted MRI in the evaluation of renal lesions: preliminary results

The purpose of this study was to evaluate the capability and the reliability of diffusion-weighted MRI in the evaluation of normal kidney and different renal lesions. 39 patients (10 normal volunteers and 29 patients with known renal lesions) underwent MRI of the kidneys by using a 1.5 T superconducting magnet. Axial fat suppressed turbo spin echo (TSE) T(2) and coronal fast field echo (FFE) T(1) or TSE T(1) weighted images were acquired for each patient. Diffusion-weighted (DW) images were obtained in the axial plane during breath-hold (17 s) with a spin-echo echo planar imaging (SE EPI) single shot sequence (repetition time (TR)=2883 ms, echo time (TE)=61 ms, flip angle=90 degrees ), with b value of 500 s mm(-2). 16 slices were produced with slice thickness of 7 mm and interslice gap of 1 mm. An apparent diffusion coefficient (ADC) map was obtained at each slice position. The ADC was measured in an approximately 1 cm region of interest (ROI) within the normal renal parenchyma, the detected renal lesions and the collecting system if dilated. ADC values in normal renal parenchyma ranged from 1.72 x 10(-3) mm(2) s(-1) to 2.65 x 10(-3) mm(2) s(-1), while ADC values in simple cysts (n=13) were higher (2.87 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1)). In hydronephrotic kidneys (n=6) the ADC values of renal pelvis ranged from 3.39 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1). In cases of pyonephrosis (n=3) ADC values of the renal pelvis were found to be lower than those of renal pelvis of hydronephrotic kidneys (0.77 x 10(-3) mm(2) s(-1) to 1.07 x 10(-3) mm(2) s(-1)). Solid benign and malignant renal tumours (n=7) showed ADC values ranging between 1.28 x 10(-3) mm(2) s(-1) and 1.83 x 10(-3) mm(2) s(-1). In conclusion diffusion-weighted MR imaging of the kidney seems to be a reliable way to differentiate normal renal parenchyma and different renal diseases. Clinical experience with this method is still preliminary and further studies are required.     

Diffusion-weighted imaging in the evaluation of odontogenic cysts and tumours

Objective The differentiation between keratocystic odontogenic tumour (KCOT) and other cystic/predominantly cystic odontogenic tumours is difficult on conventional CT and MR sequences as there is overlap in the imaging characteristics of these lesions. The purpose of this study was to evaluate the role of diffusion-weighted imaging (DWI) and to assess the performance of apparent diffusion coefficients (ADCs) in the differential diagnosis of odontogenic cysts and tumours. Methods 20 patients with odontogenic cysts and tumours of the maxillomandibular region were examined with DWI. Diffusion-weighted images were obtained with a single-shot echoplanar technique with b-values of 0, 500 and 1000 s mm(-2). An ADC map was obtained at each slice position. Results The cystic areas of ameloblastoma (n=10) showed free diffusion with a mean ADC value of 2.192±0.33×10(-3) mm(2) s(-1), whereas the solid areas showed restricted diffusion with a mean ADC value of 1.041±0.41×10(-3) mm(2) s(-1). KCOT (n=5) showed restricted diffusion with a mean ADC value of 1.019±0.07×10(-3) mm(2) s(-1). There was a significant difference between the ADC values of KCOT and cystic ameloblastoma (p<0.01, Mann-Whitney U-test). The cut-off with which KCOT and predominantly cystic ameloblastomas were optimally differentiated was 2.013×10(-3) mm(2) s(-1), which yielded 100% sensitivity and 100% specificity. Conclusion DWI can be used to differentiate KCOT from cystic (or predominantly cystic) odontogenic tumours.     

Ratings of perceived exertion at the lactate threshold in trained and untrained men and women

The purpose of this study was to investigate the effects of state of training and gender on ratings of perceived exertion (RPE) at the lactate threshold (LT), and to determine whether RPE during moderate to heavy sub-maximal exercise is more closely associated with LT or %VO2max. RPE at the LT (RPELT) and at various percentages of VO2max were compared in 10 male and 10 female trained distance runners, and 10 male and 10 female untrained subjects, 18 to 35 yr of age. Mean (+/- SD) VO2max [ml X kg FFW-1 (fat-free weight) X min-1] of the trained men and women (72.3 +/- 1.4 and 73.1 +/- 1.6) was significantly higher (P less than 0.05) than for the untrained men and women (60.2 +/- 1.4 and 53.2 +/- 1.8), confirming their higher cardiorespiratory capacity. Similarly, the mean LTs (%VO2max) of the trained men and women (79.2 +/- 1.7% and 73.3 +/- 1.8%) were significantly higher (P less than 0.05) than for the untrained men and women (66.5 +/- 3.3% and 58.9 +/- 3.3%), and mean values for the men were significantly higher (P less than 0.05) than for the women. The means for RPELT for the four groups, 13.6 +/- 2.1, 13.5 +/- 1.6, 13.5 +/- 1.5, and 12.9 +/- 1.3, respectively, were not significantly different (P greater than 0.05), even though the ratings were given at markedly different levels of VE, VO2 (1 X min-1), heart rate, and %VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)