A Validated Stability Indicating RP-UPLC Method for Atrovastain Calcium

The present paper describes stability indicating reverse phase Ultra performance liquid chromatographic (RPLC) assay method for Atrovastatin Calcium in bulk drugs. The developed method is also applicable for the related substance determination and degradation products generated from forced decomposition studies. The drug substance was subjected to stress conditions of acid hydrolysis, base hydrolysis, oxidation, photolysis and thermal degradation. The degradation of Atrovastatin was observed under acid hydrolysis, base hydrolysis and peroxide hydrolysis. The drug was found to be stable to other stress conditions attempted. Successful separation of the drug from synthetic impurities and degradation product formed under stress conditions was achieved on a C18 column using buffer 0.02 M phosphoric acid and acetonitrile. The developed UPLC method was validated with respect to linearity, accuracy, precision, specificity and ro-bustness. The developed UPLC method to determine the related substances and assay determination of Atrovastatin can be used to evaluate the quality of regular production samples. It can be also used to test the stability sample of Atrovastatin Calcium.

Degradation Pathway for Pitavastatin Calcium by Validated Stability Indicating UPLC Method

Degradation pathway for pitavastatin calcium is established as per ICH recommendations by validated and stability indicating reverse phase liquid chromatographic method. Pitavastatin is subjected to stress conditions of acid, base, oxidation, thermal and photolysis. Significant degradation is observed in acid and base stress conditions. Four impurities are studied among which impurity-4 is found prominent degradant. The stress samples are assayed against a qualified reference standard and the mass balance is found close to 99.5%. Efficient chromatographic separation is achieved on a BEH C18 stationary phase with simple mobile phase combination delivered in gradient mode and quantification is carried at 245 nm at a flow rate of 0.3 mL min-1. In the developed UPLC method the resolution between pitavastatin calcium and four potential impurities is found to be greater than 4.0. Regression analysis shows an r value (correlation coefficient) of greater than 0.998 for pitavastatin calcium and four potential impurities. This method is capable to detect the impurities of pitavastatin calcium at a level of 0.006% with respect to test concentration of 0.10 mg/mL for a 2-μL injection volume. The developed UPLC method is validated with respect to specificity, linearity & range, accuracy, precision and robustness for impurities determination and assay determination.

Blood Calcium as a Protective Factor against Traumatic Fracture

Purpose: This study aims to investigate the predictive value of blood calcium in the prognosis of traumatic fracture. Methods: A retrospective experimental design was employed, 112 cases (52 non-fracture and 60 traumatic fracture) were randomly selected. The type of fracture complies with WHO-recommended (2019) diagnostic criteria for osteoporosis combined with fracture. The blood pressure (BP) was measured by OMRON’s HEM-7136 model electronic blood pressure monitor. Blood calcium (Ca2+), and blood phosphorus (P) values were measured using Colorimetric Roche kits on a Roche/Hitachi fully automated biochemical analyzer. Data collection and analysis followed. Results: Higher levels of age, systolic and diastolic blood pressures were found in the traumatic fracture group compared to the control group, whereas weight, height, and blood phosphorus did not differ significantly (P adjusting for age, systolic blood pressure, diastolic blood pressure, and blood phosphorus, binary logistic regression analysis revealed that blood calcium was a protective factor against traumatic fracture (β = -26.85, OR = 0.00, 95% CI = 0.00 -0.02, P = 0.022). Conclusion: The findings suggest that high and low blood calcium levels may serve as useful indicators in predicting the prognosis of fractures resulting from trauma.

1,6-二磷酸果糖钙对海兰褐蛋鸡生产性能、蛋品质、血清生化指标和免疫指标的影响

试验旨在研究1,6-二磷酸果糖钙对海兰褐蛋鸡生产性能、蛋品质、血清生化指标和免疫指标的影响。试验选择800只健康、产蛋率相近的380日龄海兰褐蛋鸡,随机分成4组,每组20个重复,每个重复10笼,每笼1只鸡。对照组、低剂量组、中剂量组和高剂量组分别在基础日粮中添加0mg/kg、100mg/kg、200mg/kg和300mg/kg1,6-二磷酸果糖钙,进行为期9周的试验。结果显示:与对照组相比,中、高剂量组产蛋率显著提高(P<0.05),且与1,6-二磷酸果糖钙的添加量呈二次曲线关系(P<0.05);低、中和高剂量组破蛋率显著降低(P<0.05)。中、高剂量组蛋黄颜色和蛋壳强度显著提高(P<0.05),蛋壳强度与1,6-二磷酸果糖钙添加量呈二次曲线关系(P=0.024);低、中和高剂量组的蛋壳比例显著提高(P<0.05),且随1,6-二磷酸果糖钙添加量的增加呈线性升高(P=0.034)。低、中和高剂量组谷丙转氨酶活性显著降低(P<0.05);低、中剂量组总胆固醇含量显著降低(P<0.05),且总胆固醇含量与1,6-二磷酸果糖钙添加量呈二次曲线关系(P=0.004);中、高剂量组高密度脂蛋白含量显著提高(P<0.05);中剂量组低密度脂蛋白含量显著降低(P<0.05),且低密度脂蛋白含量与1,6-二磷酸果糖钙添加量呈二次曲线关系(P=0.036)。低、中和高剂量组的IgM和IgA含量均显著增加(P<0.05),其中IgA含量随1,6-二磷酸果糖钙添加量的增加呈线性升高(P=0.047)。分别对产蛋率、蛋壳强度、总胆固醇含量和低密度脂蛋白含量进行二次曲线方程拟合表明,当1,6-二磷酸果糖钙添加量分别为179、186、243和268mg/kg时,产蛋率、蛋壳强度、总胆固醇含量和低密度脂蛋白含量分别达到最佳。研究提示:日粮中添加200和300mg/kg1,6-二磷酸果糖钙较佳,基于产蛋率、蛋壳强度、总胆固醇含量和低密度脂蛋白含量考虑,适宜的1,6-二磷酸果糖钙添加量分别为179、186、243和268mg/kg。

妊娠期高血压疾病患者孕中期血小板参数、钙离子浓度、凝血指标与病情程度及母婴结局相关性研究

目的:观察妊娠期高血压疾病(PIH)患者孕中期血小板参数、钙离子(Ca^(2+))浓度、凝血指标与病情程度及母婴结局的关系。方法:选取120例PIH患者作为PIH组,根据病情程度将其分为轻度组、中度组及重度组,另外选取同期100例健康孕妇作为对照组,比较各组患者孕中期血小板参数[血小板计数(PLT)、血小板分布宽度(PDW)、平均血小板体积(MPV)]、Ca^(2+)浓度及凝血指标[凝血酶原时间(PT)、凝血酶时间(TT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(FIB)]水平。根据PIH组母婴结局将其进一步分为不良结局组与良好结局组,采用受试者工作特征(ROC)曲线分析其对PIH患者母婴结局的预测价值。结果:PIH组患者PLT、Ca^(2+)浓度、PT、APTT低于对照组(均P<0.05),PDW及FIB高于对照组(均P<0.05)。轻度组患者PLT、Ca^(2+)浓度、PT、APTT高于中度组与重度组,PDW低于中度组与重度组(均P<0.05),且Spesrman相关性分析显示,PIH患者病情严重程度与PLT、Ca^(2+)浓度、PT、APTT呈负相关,与PDW水平呈正相关(均P<0.05)。120例PIH患者中,共34例出现不良母婴结局(早产15例、新生儿窒息10例、宫内窘迫8例、围产期死亡1例),不良结局组患者PLT、Ca^(2+)浓度、PT、APTT均低于良好结局组(均P<0.05)。ROC特征曲线结果显示,PLT、Ca^(2+)浓度、PT、APTT预测母婴结局的最佳截断值分别为143.760×10^(9)、2.875 mmol/L、10.715 s及29.020 s,且四项指标联合预测PIH患者母婴结局的AUC及敏感度均高于单一指标预测(均P<0.05)。结论:PIH患者病情严重程度与PLT、Ca^(2+)浓度、PT、APTT及PDW水平密切相关,且PLT、Ca^(2+)浓度、PT联合APTT对PIH患者母婴结局具有较高的预测价值,建议临床予以重点关注。

饲料钙磷水平对禾花鲤生长性能、血清生化指标、骨骼及肝脏组织形态的影响

试验旨在探讨饲料中不同钙磷水平对禾花鲤生长性能、血清生化指标、骨骼及肝脏组织形态的影响。试验以氯化钙为钙源设2个钙水平:0、0.5%(A、B),以磷酸二氢钾为磷源设4个磷水平:0、0.5%、1.0%、1.5%(1、2、3、4),采用交叉组合制备A1(0钙、0磷)、A2(0钙、0.5%磷)、A3(0钙、1.0%磷)、A4(0钙、1.5%磷)、B1(0.5%钙、0磷)、B2(0.5%钙、0.5%磷)、B3(0.5%钙、1.0%磷)、B4(0.5%钙、1.5%磷)8组等氮饲料,选择初始体重为(4.46±0.02) g的禾花鲤1 440尾,随机分为8组,每组3个重复,每个重复60尾鱼,养殖60 d。试验结果表明:(1)禾花鲤的终末体重(FBW)、增重率(WGR)、特定生长率(SGR)在钙磷水平分别为0.5%、1.5%(B4)时达最大值,显著大于A4和B1组(P<0.05)。饲料系数(FCR)在钙磷水平分别为0.5%、1.5%时达最小值,显著低于A4和B1组(P<0.05)。(2)饲料磷水平升高显著降低禾花鲤粗脂肪含量(P<0.05)。粗蛋白含量随饲料磷升高而增加,与不添加钙组相比,添加钙减少蛋白质沉积。鱼体钙含量随磷水平升高而增加,但B4组禾花鲤钙含量显著低于B3组(P<0.05)。(3)血清谷草转氨酶(AST)和碱性磷酸酶(ALP)活性在钙磷水平分别为0.5%、1.0%时达最小值。总胆固醇(T-CHO)含量随饲料磷水平升高呈降低趋势。(4) X光片显示,A1组脊椎骨发生融合,A3、A4和B1组尾脊椎骨发生不同程度畸形。(5)当饲料钙水平为0时,饲料磷水平升高可缓解肝细胞空泡化,当磷水平为1.5%时造成脂肪堆积和核偏移;当钙水平为0.5%时,饲料磷水平升高可减少肝细胞损伤,且肝细胞完整性更好。综上所述,建议禾花鲤饲料钙磷水平分别为0.5%、1.0%~1.5%,有利于禾花鲤的生长及鱼体健康。

Functional optoacoustic neuro-tomography for scalable whole-brain monitoring of calcium indicators

Non-invasive observation of spatiotemporal activity of large neural populations distributed over entire brains is a longstanding goal of neuroscience.We developed a volumetric multispectral optoacoustic tomography platform for imaging neural activation deep in scattering brains.It can record 100 volumetric frames per second across scalable fields of view ranging between 50 and 1000 mm^(3) with respective spatial resolution of 35–200μm.Experiments performed in immobilized and freely swimming larvae and in adult zebrafish brains expressing the genetically encoded calcium indicator GCaMP5G demonstrate,for the first time,the fundamental ability to directly track neural dynamics using optoacoustics while overcoming the longstanding penetration barrier of optical imaging in scattering brains.The newly developed platform thus offers unprecedented capabilities for functional whole-brain observations of fast calcium dynamics;in combination with optoacoustics'well-established capacity for resolving vascular hemodynamics,it could open new vistas in the study of neural activity and neurovascular coupling in health and disease.

Structural basis of the ultrasensitive calcium indicator GCaMP6

GCaMP is one of the most widely used calcium indicators in neuronal imaging and calcium cell biology. The newly developed GCaMP6 shows superior brightness and ultrasensitivity to calcium concentration change. In this study, we determined crystal structures of CaZ＋-bound GCaMP6 monomer and dimer and presented detailed structural analyses in comparison with its par- ent version GCaMP5G. Our analyses reveal the structural basis for the outperformance of this newly developed Ca2＋ indicator. Three substitution mutations and the resulting changes of local structure and interaction explain the ultrasensitivity and in- creased fluorescence intensity common to all three versions of GCaMP6. Each particular substitution in the three GCaMP6 is also structurally consistent with their differential sensitivity and intensity, maximizing the potential of using GCaMP6 in solving diverse problems in neuronal research and calcium signaling. Our studies shall also be beneficial to further structure-guided optimization of GCaMP and facilitate the design of novel calcium indicators.

牙体牙髓病患者应用一次性根管术填充Vitapex糊剂与ApexitPlus氢氧化钙糊剂的临床疗效比较

目的:探讨牙体牙髓病患者应用一次性根管术填充Vitapex糊剂与ApexitPlus氢氧化钙糊剂的临床疗效。方法:选取104例行一次性根管术治疗的患者为研究对象,根据根管填充剂不同分为对照组和观察组,每组各52例。观察组患者使用Vitapex糊剂填充根管;对照组使用ApexitPlus氢氧化钙糊剂填充根管,术后随访3个月。比较两组患者术后根管填充效果、根尖周指数(PAI)、临床附着水平(CAL)、白细胞介素1β(IL-1β)、IL-6、静息痛、咀嚼痛、临床疗效、并发症及不良反应发生情况。结果:观察组患者一次性根管术中超充2例,恰充46例,欠充4例;对照组患者超充1例,恰充45例,欠充6例,两组患者填充效果比较,差异无统计学意义(P>0.05)。术后3个月,两组患者PAI、CAL、血清IL-1β及IL-6、静息痛及咀嚼痛评分均降低(P<0.05),且观察组低于对照组(P<0.05);观察组患者治疗有效率高于对照组(96.15%vs.84.62%,P<0.05)。两组患者术后均未出现严重并发症及不良反应。结论:Vitapex糊剂与ApexitPlus氢氧化钙糊剂应用于牙体牙髓病一次性根管填充术中,均具有良好的填充效果,但Vitapex糊剂在减轻术后疼痛反应及促进牙周愈合中的效果更优。

干旱胁迫及钙胁迫对血人参幼苗生长的影响

为了探讨CaCl_(2)胁迫和干旱胁迫对血人参幼苗生长的影响,分别采用不同浓度梯度的CaCl_(2)溶液和不同干旱环境对血人参幼苗进行胁迫实验。结果表明,随着土壤含水量的升高,血人参幼苗总的生物量呈上升趋势,血人参总叶绿素含量最适合的相对田间持水量为60%~65%;在极度干旱条件下,丙二醛(MDA)含量和游离脯氨酸(Pro)含量最低,过氧化氢酶(CAT)活性最强。在适宜的钙浓度(5~35 mmol/L)环境下,可以促进血人参幼苗的胚根、主根、鲜重等生长发育;在钙浓度过量时,反而会产生抑制作用。在适宜的钙胁迫浓度(5~35 mmol/L)范围内,血人参幼苗中MDA含量与叶绿素的含量有所增加,同时SOD活性、POD活性、Pro含量及CAT的活性升高。综合分析表明,钙离子浓度过高或过低均会抑制血人参幼苗的生长,其幼苗虽具有一定的抗旱性,但随着干旱程度的加深,幼苗植株的生长会受到抑制。因此,在血人参的引种繁育过程中,应注意适当的保水、补水和控制钙离子浓度。

直读式测钙仪电计电位校准方法研究

介绍了直读式测钙仪电计电位的校准方法,包括电计电位示值误差和重复性测量方法,以及对仪器电计电位示值误差测量不确定度的评定等。

直读式测钙仪法水泥剂量的测量不确定度评定

研究了直读式测钙仪水泥剂量的校准方法,阐明了直读式测钙仪原理,介绍了校准用标准溶液的配制,给出仪器示值误差和重复性的测定步骤,列出了示值误差测量不确定度评定方法。

低分子肝素钙与来曲唑联合治疗多囊卵巢综合征的作用及对血清相关指标的影响

目的 分析低分子肝素钙与来曲唑联合治疗多囊卵巢综合征的应用效果及对血清指标的影响。方法 将我院2019年3月至2023年6月在门诊收治的75例多囊卵巢患者通过随机的方式分为对照组和研究组,其中对照组实施来曲唑进行促排卵治疗,研究组给予肝素联合来曲唑治疗,连续治疗3周后,比较两组患者的治疗效果。结果 治疗前,两组血清性激素指标差异无统计学意义(P> 0.05);治疗后,对照组E2指标低于研究组,其余指标(T、PRL、LH、FSH)均高于研究组(P均<0.05)。治疗后,对照组排卵率54.05%低于研究组排卵率81.57%(χ^(2)=6.527,P=0.010);对照组妊娠率24.32%低于研究组68.64%(χ^(2)=14.646,P <0.001)。结论 低分子肝素钙联合来曲唑应用于多囊卵巢综合征患者的治疗中,其血清激素指标得到显著改善,其排卵率、妊娠率也显著提高。

Structural insight into enhanced calcium indicator GCaMP3 and GCaMPJ to promote further improvement

Genetically encoded Ca^(2+) indicators(GECI)are important for the measurement of Ca^(2+) in vivo.GCaMP2,a widelyused GECI,has recently been iteratively improved.Among the improved variants,GCaMP3 exhibits significantly better fluorescent intensity.In this study,we developed a new GECI called GCaMPJ and determined the crystal structures of GCaMP3 and GCaMPJ.GCaMPJ has a 1.5-fold increase in fl uorescence and 1.3-fold increase in calcium affi nity over GCaMP3.Upon Ca^(2+) binding,GCaMP3 exhibits both monomeric and dimeric forms.The structural superposition of these two forms reveals the role of Arg-376 in improving monomer performance.However,GCaMPJ seldom forms dimers under conditions similar to GCaMP3.St ructural and mutagenesis studies on Tyr-380 confi rmed its importance in blocking the cpEGFPβ-barrel holes.Our study proposes an efficient tool for mapping Ca^(2+) signals in intact organs to facilitate the further improvement of GCaMP sensors.

维生素D钙咀嚼片联合rhGH治疗儿童生长激素缺乏症的临床效果

目的:探析维生素D钙咀嚼片联合重组人生长激素(rhGH)治疗儿童生长激素缺乏症(GHD)的临床效果。方法:采用目的抽样法纳入2022年1月—2023年12月石狮市医院收治的72例GHD患儿作为研究对象。采用随机数表法将纳入患者分为对照组和观察组,各36例。对照组给予rhGH治疗,观察组给予维生素D钙咀嚼片联合rhGH治疗,比较两组维生素D相关指标{25羟维生素D_(3)[25-(OH)D_(3)]、1,25-二羟维生素D_(3)[1,25-(OH)_(2)D_(3)]}、体格相关指标[身高标准差分值(HtSDS)、身高增长速度、骨龄]、骨代谢指标[碱性磷酸酶(BAP)、Ⅰ型骨胶原C终端端肽(ⅠCTP)、骨钙素]、甲状腺功能[游离三碘甲状腺原氨酸(FT_(3))、游离四碘甲状腺原氨酸(FT_(4))、促甲状腺激素(TSH)]、生长因子[胰岛素样生长因子-1(IGF-1)、胰岛素样生长因子结合蛋白-3(IGFBP-3)]、临床效果。结果:治疗前,两组维生素D相关指标、体格相关指标、骨代谢指标、甲状腺功能及生长因子水平比较,差异无统计学意义(P>0.05);治疗后,两组25-(OH)D_(3)、1,25-(OH)_(2)D_(3)、BAP、ⅠCTP、骨钙素、FT_(3)、FT_(4)、IGF-1、IGFBP-3水平、HtSDS、身高增长速度、骨龄高于治疗前,TSH水平低于治疗前,且观察组优于对照组,差异有统计学意义(P<0.05)。观察组临床总有效率为94.44%,高于对照组的77.78%,差异有统计学意义(P<0.05)。结论:维生素D钙咀嚼片联合rhGH治疗儿童GHD临床效果确切,与单用rhGH相比,可以更好改善患儿维生素D相关指标、体格相关指标、骨代谢指标、甲状腺功能及生长因子,同时也能有效提升治疗效果。

阿托伐他汀钙不同剂量治疗老年冠心病患者临床效果及安全性比较

目的:探讨强化剂量与序贯剂量阿托伐他汀钙对老年冠心病患者的影响。方法:选取本院2021年1月-2022年11月收治的80例老年冠心病患者为研究对象,按照随机数字表法分为两组。对照组(n=40例)予以强化剂量阿托伐他汀钙治疗,40 mg/次,1次/d,连续服用12个月;观察组(n=40例)予以序贯剂量阿托伐他汀钙治疗,初始剂量为40 mg/次,1次/d,连续用药1个月,随后剂量减至20 mg/次,1次/d,共治疗12个月。比较两组心功能、血清学指标、炎症反应、生活质量、主要心脏不良事件及不良反应发生率。结果:治疗前,两组每搏输出量(SV)、心输出量(CO)、左室射血分数(LVEF)、高密度脂蛋白胆固醇(HDL-C)、左室舒张末期内径(LVEDD)、低密度脂蛋白胆固醇(LDL-C)、三酰甘油(TG)、丙氨酸氨基转移酶(ALT)、天门冬氨基酸转移酶(AST)、C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)和各项生活质量综合评定问卷(GQOLI-74)指标比较无统计学差异(P>0.05);治疗后,两组SV、CO、LVEF、HDL-C以及各项GQOLI-74指标均较治疗前升高,且观察组高于对照组,两组LVEDD、LDL-C、TG、ALT、AST、CRP和TNF-α水平均较治疗前下降,且观察组低于对照组,具有统计学差异(P<0.05)。两组主要不良心脏事件发生率比较无统计学差异(P>0.05)。观察组不良反应发生率低于对照组,具有统计学差异(P<0.05)。结论:在老年冠心病患者中应用序贯剂量阿托伐他汀钙治疗效果更佳,可促进机体内血清学指标改善,减轻炎症反应,提高心功能,减少不良反应发生,改善生活质量。

二溴茜素紫作为钙的络合滴定指示剂研究

研究了二溴茜素紫(DBV)作为钙的络合滴定新指示剂,测定了Ca-DBV络合物的稳定常数。与常用的钙指示剂相比,试剂稳定,变色敏锐,常见金属离子不干扰测定。已用于水、白云石、水泥等样品中钙的测定。

不同温度和铝浓度对麻疯树生理指标的影响及外源钙的作用

以攀枝花地区麻疯树为材料,采用溶液培养方法,设置不同温度(24、29、34℃),研究不同浓度酸铝胁迫(Al3+的浓度为:对照、0.01、0.11、5、mmol/L)对3月龄麻疯树幼苗根系活力、叶片丙二醛(MDA)含量、叶片脯氨酸(Pro)含量、过氧化物酶(POD)活性等生理指标的影响.结果表明:①相同Al3+浓度处理下,随温度升高,幼苗根系活力降低,MDA、Pro含量增加,POD活性增加;②相同温度处理下,随Al3+浓度增加,根系活力呈下降趋势,叶片MDA含量、Pro含量及POD活性呈上升趋势;③适度低温,适量的Al3+(29℃,Al3+浓度为0.01 mmol/L;24℃,Al3+浓度为0.01、0.1 mmol/L)能增强根系活力,降低MDA和Pro含量,降低POD活性,有益于麻疯树幼苗的生长;④当Al3+浓度增至1 mmol/L以上时,3个温度下处理的麻疯树幼苗都受到不同程度的伤害;⑤29℃、1 mmol/L Al3+浓度下,增加溶液中Ca2+浓度能减小酸铝对麻疯树幼苗的毒害作用.

不同钙盐对温州蜜柑抗冻性的影响

用20mmol.L-1氯化钙(CaCl2)、醋酸钙(CaAc2)和硝酸钙(Ca(NO3)2)喷施"国庆1号"温州蜜柑叶片,研究3种钙盐对其叶片抗冻性的影响.结果表明:喷施钙盐降低了叶片半致死温度(LT50),提高了温州蜜柑的抗冻性,CaCl2处理的LT50比对照降低了0.54℃,而CaAc2和Ca(NO3)2处理分别比对照降低了1.34℃和1.35℃,表明CaCl2处理效果较差,CaAc2和Ca(NO3)2处理效果较好.钙盐处理还提高了"国庆1号"温州蜜柑叶片在低温(-9℃)胁迫下的SOD、POD活性及可溶性蛋白质、可溶性糖和脯氨酸含量,减少了叶片MDA的积累.

饲粮中添加脂肪酸钙和烟酸铬对热应激奶牛产奶性能、生理指标及血清生化指标的影响

本试验旨在研究饲粮中添加脂肪酸钙和烟酸铬对热应激奶牛产奶性能、生理指标及血清生化指标的影响。采用随机区组试验设计,根据年龄、胎次(2～3胎)、产奶量、泌乳期相近的原则,将21头健康奶牛分为3组,每组7个重复,对照组、Ⅰ组和Ⅱ组分别饲喂基础饲粮、基础饲粮+250 g/d脂肪酸钙和基础饲粮+10 mg/kg烟酸铬。预试期10 d,正试期40 d。试验期内日平均温湿指数(THI)为79.99。结果表明:1)饲粮添加脂肪酸钙和烟酸铬分别使标准乳产量极显著提高了26.37%(P<0.01)、10.78%(P<0.01);饲粮添加脂肪酸钙使乳脂率极显著提高了31.61%(P<0.01)。2)饲粮添加脂肪酸钙和烟酸铬分别使呼吸频率显著降低了10.01%(P<0.05)、11.69%(P<0.01)。3)饲粮添加脂肪酸钙和烟酸铬分别使血清谷草转氨酶活性极显著降低了25.80%(P<0.01)、19.00%(P<0.01),血清肌酸激酶活性分别显著降低了9.88%(P<0.05)、8.89%(P<0.05);饲粮添加脂肪酸钙使血清三碘甲状腺原氨酸(T3)、甲状腺素(T4)和丙二醛(MDA)浓度分别显著提高了14.47%(P<0.05)、23.12%(P<0.01)和38.89%(P<0.05);饲粮添加烟酸铬使血清T3、超氧化物歧化酶(SOD)浓度分别显著提高了11.84%(P<0.05)、32.61%(P<0.05);饲粮添加脂肪酸钙和烟酸铬分别使血清热休克蛋白70(HSP70)表达量显著提高了39.94%(P<0.01)、28.10%(P<0.05)。结果提示,饲粮添加脂肪酸钙和烟酸铬可提高产奶量,通过调节内分泌、增强抗氧化能力、调节HSP70表达等来增强奶牛耐热性。