参麦注射液辅助治疗慢性心衰患者的临床疗效观察

目的:评价参麦注射液辅助治疗慢性充血性心力衰竭(congestive heart failure,CHF)的临床疗效,并探讨其对患者血清超敏C反应蛋白(high-sensitivity C-reactive protein,hsCRP)及脑钠肽(brain natriuretic peptide,BNP)水平的影响.方法:选择心功能Ⅱ～Ⅳ级(NYHA)的CHF患者120例,随机分为对照组和治疗组(每组60例),两组患者均予常规治疗,治疗组在常规治疗基础上静滴参麦注射液,两组均治疗15天,检测和比较两组治疗前后患者的血清hsCRP、BNP水平和心脏超声测定左心室射血分数(LVEF)及左心室舒张末期内径(LVEDd).结果:对照组和治疗组的心功能临床有效率分别为73.7％和88.7％,治疗组显著高于对照组(P＜0.05).治疗后,两组LVEF均较治疗前明显升高(P＜0.05),LVEDd均较治疗前明显缩小(P＜0.05),且治疗组与对照组相比有统计学差异(P＜0.05).而治疗后,两组血浆BNP和hsCRP水平均较治疗前显著下降(P＜0.01),且治疗组显著低于对照组(P＜0.05).两组治疗过程中均无明显不良反应发生.结论:参麦注射液辅助治疗CHF的疗效较常规治疗更好,可显著降低患者血清hsCRP、BNP水平,改善左室功能.     

呋塞米联合硝普钠注射液治疗顽固性心力衰竭的临床效果研究

目的:探讨呋塞米与硝普钠注射液联合治疗顽固性心力衰竭的临床效果及安全性。方法:选择2016年5月至2018年5月在我院进行治疗的90例顽固性心力衰竭患者,按照随机数字表法分为观察组和对照组。对照组给予基础治疗,观察组以对照组为基础加用呋塞米联合硝普钠注射液治疗。治疗后,观察和比较两组的临床疗效、治疗前后血清B型脑钠肽(BNP)、C-反应蛋白(CRP)水平及心功能[左室射血分数(LVEF)、左室舒张末容积指数(LVEDVI)、左室收缩末容积指数(LVESVI)、左室舒张早期与晚期充盈速度比值(E/A)]的变化。结果:治疗后,观察组总有效率(91.1%)明显高于对照组(66.7%)(P0.05)。与治疗前相比,两组患者治疗后的血清BNP、CRP、LVEDVI、LVESVI水平均明显低于治疗前,LVEF、E/A明显高于治疗前(P0.05);与对照组相比,观察组治疗后血清BNP、CRP、LVEDVI、LVESVI水平均明显降低,LVEF、E/A显著升高(P0.05)。两组治疗期间均未发生严重不良反应。结论:与常规治疗相比,呋塞米联合硝普钠注射液治疗顽固性心力衰竭患者可更有效改善其心功能,提高其临床疗效,且安全性高。     

托拉塞米联合川芎嗪注射液治疗慢性心力衰竭的疗效及对患者血清MCP-1、BNP、NGAL水平的影响

目的:探讨托拉塞米联合川芎嗪注射液治疗慢性心力衰竭的临床疗效及对患者血清单核细胞趋化蛋白因子-1(MCP-1)、脑钠肽(BNP)、中性粒细胞明胶酶相关脂质运载蛋白(NGAL)水平的影响。方法:选择2015年3月～2017年3月于我院住院的慢性心力衰竭患者100例,按随机数字表法将其分成治疗组(n=50)与对照组(n=50)。两组患者均给予相同的常规治疗,对照组在此基础上联合托拉塞米治疗,治疗组在对照组基础上加用川芎嗪注射液治疗。在完成2周治疗后,对两组进行疗效评价,比较两组治疗前后心功能、6 min步行距离(6MWT)及生活质量水平、血清MCP-1、BNP、NGAL水平的变化。结果:治疗组经2周治疗后总有效率为86.00%(43/50),与对照组[64.00%(32/50)]相比显著上升(P0.05)。治疗组治疗2周后左室射血分数(LVEF)值较治疗前显著升高(P0.05),而左室舒张/收缩末期容积(LVEDV/LVESV)均显著降低(P0.05);与治疗前对比,对照组治疗后LVEF值亦显著增加(P0.05),LVESV值显著下降(P0.05);且治疗组治疗后上述心功能指标改善效果均显著优于对照组同期(P0.05)。与治疗前相比,两组治疗2周后6MWT值均明显增加(P0.05),明尼苏达心力衰竭生活质量量表(LHFQ)评分及血清MCP-1、BNP、NGAL水平均明显降低(P0.05);且治疗组治疗后以上指标改善效果较对照组同期更显著(P0.05)。结论:托拉塞米联合川芎嗪注射液治疗慢性心力衰竭的临床疗效明显优于单用川芎嗪注射液治疗,其可有效改善患者心功能,提高生活质量,可能与其显著降低患者血清MCP-1、BNP、NGAL水平有关。     

rhBNP治疗射血分数保留急性心力衰竭的临床研究

目的:探讨重组人脑利钠肽(rh BNP)对急性射血分数保留心力衰竭的临床治疗作用。方法:选择2008年6月至2014年6月间我院收治的20例急性射血分数保留心力衰竭患者为研究对象,其中10例予以硝普钠静脉注射48小时,10例予以rh BNP静脉注射48小时。48小时后,评估和比较两组患者心力衰竭的临床改善情况;72小时后,复查和比较两组患者血浆NT-pro BNP的下降值。结果:硝普钠组患者呼吸困难缓解积分(1.4±1.35)明显低于rh BNP组(3.5±0.71),rh BNP组呼吸困难缓解时间(3.68±1.69 h)显著短于硝普钠组(21.50±18.43 h),血浆NT-pro BNP浓度下降值(864.60±585.92 pg/ml)明显高于硝普钠组(423.30±284.06 pg/ml)。结论:rh BNP治疗急性射血分数保留心力衰竭的临床疗效优于硝普钠。     

肺炎合并心力衰竭患者血浆BNP,cTn1的变化及其临床意义

目的:探讨血浆脑钠肽(BNP)和心肌肌钙蛋白(cTn1)在肺炎合并心力衰竭患者血浆脑钠肽(BNP)和心肌肌钙蛋白(cTn1)的变化情况及、肺炎未合并心衰患者及健康对照组中的不同表达,探讨血浆脑钠肽(BNP)和心肌肌钙蛋白(cTn1)与疾病变化的关系及在肺炎合并心力衰竭中的临床诊断的意义.方法:回顾性分析我院自2010年1月至2012年1月收治的42例肺炎合并心衰患者,同期收治的肺炎末合并心衰患者34例为阳性对照组,以及同期在门诊进行体检的30例健康患者为阴性对照组.在入院后24h之内评估心脏功能并检测血浆BNP及cTn1水平变化,以及心衰合并肺炎患者入院24h急性期及心衰恢复期BNP和cTn1水平的变化,比较BNP和cTn1在的不同表达.结果:心衰组、阳性对照组、阴性对照组患者BNP(378.14,142.53,0.74±0.15)和cTn1 (0.84,0.32,0.18)比较,在统计学上具有显著性意义(H=140.67,H=30.14,P＜0.001).心衰急性期与心衰恢复期BNP(378.14,140.32)和cTn1(0.84,0.04)水平比较,在统计学上具有显著性差异(t=2.044,t=2.051,P＜ 0.05).结论:BNP与cTn1在肺炎合并心衰患者为高表达,显著高于肺炎未合并心衰患者,合并心衰与未合并心衰组的BNP与cTn1水平也显著高于健康对照组,表明BNP与cTn1的表达与病情呈正相关.且在肺炎合并心衰急性期的表达高于恢复期,表明BNP、cTnⅠ水平变化可为诊断患者病情严重程度及肺炎合并心衰为急性期或慢性提高依据,可以为早期心功能衰竭提高临床参考.     

厄贝沙坦对慢性心力衰竭患者血清骨桥蛋白水平的影响

目的:探讨厄贝沙坦对心力衰竭(心衰)患者血清骨桥蛋白(OPN)水平及心功能的影响.方法:选择心衰患者106例,随机分为两组,并随机接受厄贝沙坦治疗,每组均为53例,常规治疗组,予以利尿剂、洋地黄制剂和β受体阻滞剂常规治疗,厄贝沙坦组,在常规治疗下加用厄贝沙坦150 mg/d,治疗12周,比较治疗前后各组患者血清OPN、B型利钠肽(BNP)水平、左室射血分数(LVEF)及左室舒张末内径(LVEDd).结果:心衰患者随着心衰程度的加重,血清OPN、BNP水平及LVEDd逐渐升高,而LVEF逐渐降低(P＜0.0l);与治疗前相比,治疗后两组患者血清OPN及BNP水平均明显降低(P＜0.01),而LVEF升高,LVEDd降低(P＜0.05),但厄贝沙坦组OPN、BNP水平及LVEF、LVEDd较常规治疗组变化更显著(P＜0.05).结论:OPN可反映心衰严重程度及判断患者的预后,在常规心衰治疗的基础上加服厄贝沙坦能进一步降低血清OPN水平,改善心功能及心衰患者的预后.     

螺内酯对充血性心衰患者心功能和血浆脑钠肽的影响

目的:观察螺内酯治疗充血性心力衰竭患者前后心功能和脑钠肽的变化及临床意义.方法:选取2008-2010年沈阳军区总医院心内科门诊的充血性心力衰竭患者70例,随机分为螺内酯治疗组和对照组,对照组采用常规内科治疗.螺内酯治疗组在常规内科治疗的基础上加用螺内酯治疗.结果:两组治疗前左室收缩末期容积(LVESV),左心室射血分数(LVEF),血浆BNP水平比较无差异(P＞0.05),治疗后两组LVESV,血浆BNP明显下降,LVEF水平明显升高(P＜0.05).螺内酯治疗组临床疗效高于对照组(P＜0.05).结论:螺内酯可以改善充血性心力衰竭患者的心脏功能.     

硝普钠治疗风湿性心脏病并发心衰患者的临床效果研究

目的:探讨硝普钠治疗风湿性心脏病并发心衰患者的临床效果及安全性。方法:选取内蒙古医科大学第三附属医院2016-2019年收治的80例风湿性心脏病并发心衰患者,将其随机分为研究组和对照组,每组40例。对照组采取常规治疗,研究组在此基础上应用硝普钠治疗,对比两组治疗前后心脏血流动力学参数、舒张压、收缩压、心率、呼吸的变化、临床效果及不良反应的发生情况。结果:两组治疗后左心室收缩末期内径(Left ventricular end-systolic diameter,LVESD)、左房内径(left atrial diameter,LAD)、左心室舒张末期内径(left ventricular end-diastolic diameter,LVEDD)均较治疗前明显降低,左室射血分数值(left ventricular ejection fraction,LVEF)均明显高于治疗后(P0.05),且研究组上述指标的改善程度均明显优于对照组(P0.05)。研究组治疗后舒张压、收缩压、心率、呼吸低于对照组(P0.05);研究组的治疗有效率心脏高于对照组(P0.05);两组不良反应的发生率比较差异无统计学意义(P0.05)。结论:硝普钠治疗风湿性心脏病并发心衰患者应可有效改善患者心功能,提高临床治疗效果,具安全性较好。     

小剂量螺内酯联合美托洛尔对慢性心力衰竭患者血浆NT-p roBNP、CRP水平及心功能的影响

目的:观察小剂量螺内酯联合美托洛尔对慢性心力衰竭患者血浆NT-p roBNP、CRP水平及心功能的影响.方法:将71例慢性心力衰竭(心衰)患者随机分为治疗组和对照组,均予常规抗心衰治疗,治疗组加服小剂量螺内酯联合美托洛尔,疗程12周.治疗前后用彩超测定心功能指标左心室射血分数(LVEF),ELISA法和散射比浊法测定血浆N2末端脑钠肽前体(NT-proBNP)、C反应蛋白(CRP)水平.结果:治疗后治疗组总有效率明显高于对照组,心功能指标LVEF明显升高,血浆NT-proBNP、CRP水平均明显下降,P均＜0.05;治疗组血浆NT-p roBNP与LVEF呈负相关(r=0.75,P＜0.05);血浆CRP水平与LVEF增加呈负相关(r=0.433,P＜0.05).结论:小剂量螺内酯联合美托洛尔治疗慢性心衰效果确切,其主要作用机制为降低血浆NT-proBNP、CRP水平和改善心功能.     

BNP、NT-proBNP与心衰进程的诊断价值和相关性研究

目的:检测心力衰竭患者血清脑钠肽(BNP)及N末端脑钠肽前体(NT-proBNP)水平,分析其与心功能的相关性以及对心力衰竭的诊断价值。方法:选取我科治疗的慢性心衰患者58例并按照NYHA心功能分级,比较不同心功能分级的患者血清BNP、NT-proBNP的水平及其与射血分数等指标的相关性,并分析BNP与NT-proBNP的诊断价值。结果:①各心功能分级间采用单因素方差分析发现,BNP、NT-proBNP随心功能分级增加而增加(P<0.05),不同心功能分级的组间比较发现,除III级与IV级BNP、NT-proBNP、LVEF、6min步行距离差异不明显(P>0.05),其余组间比较均具有显著性差异(P<0.05)。②经比较发现,BNP、NT-proBNP均与LVEF、6min步行距离呈负相关,而与左室舒张末期内径、左室收缩末期内径呈正相关。③NT-proBNP诊断效力高于BNP。结论:血清BNP和NT-proBNP可作为评估左心室功能不全和左心室结构改变的临床指标。     

Tuning of electronic properties of one-dimensional cyano-bridged Cu-Ni, Cu-Pd, and Cu-Pt bimetallic assemblies by stereochemistry of ligands

Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)₂][Pd(CN)₄] · 2H₂O (1), [Cu(trans-chxn)₂][M(CN)₄] · 2H₂O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)₂][M(CN)₄] · 2H₂O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p_1/2 and 2p_3/2 peaks of XPS and broad d-d bands around 18 000 cm⁻¹ of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.     

Structure and function of S-adenosylhomocysteine hydrolase

In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine (AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations. These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate (NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases, with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the catalytic domain occurs upon inhibitor/substrate binding.     

Influence of Fluoride on Rat Kidney Antioxidant System: Effects of Methionine and Vitamin E

The aim of the study has been to determine and compare the influence upon the kidney antioxidative system, exercised by administration of vitamin E, and vitamin E in combination with methionine, under conditions of oxidative stress induced by sodium fluoride. The experiment was carried out on Wistar FL rats (adult males) that, for 35 days, were administered water, NaF, NaF with vitamin E, or vitamin E with methionine (doses: 10 mg NaF/kg of body mass/24 h, 3 mg vitamin E per 10 μl per rat for 24 h, 2 mg methionine per rat for 24 h). The influence of administered sodium fluoride and antioxidants upon the antioxidative system in kidney was examined by analyzing the concentration of malondialdehyde (MDA) and the activity of the most important antioxidative enzymes (SOD, total and both its isoenzymes, GPX, GST, GR, and CAT). The studies carried out confirmed the disadvantageous effect of the administered dose of NaF upon the antixodiative system in rats (increase in the concentration MDA, decrease activity of all antioxidative enzymes). The administration of vitamin E increased the activity of studied enzymes with the exception of glutathione reductase GR; it also reduced the procesess of lipid peroxidation. It has been found that combined doses of vitamin E and methionine were most effective in inhibiting lipid peroxidation processes. The results confirmed the antioxidative properties of methionine.     

Reorientation of Microfibrils and Microtubules at the Outer Epidermal Wall of Maize Coleoptiles During Auxin-Mediated Growth

Auxin-mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.     

Land,livestock, and livelihoods: Changing dynamics of gender,caste, and ethnicity in a Nepalese Village

Over the past 10 years, Ghusel VDC, Lalitpur District has moved from primarily subsistence agriculture into the wider cash economy aided by the Small Farmers' Development Program (SFDP), which provides credit to farmers mainly for the purchase of buffalo for milk production, and by the National Dairy Corporation, which supports local dairy cooperatives. Analysis reveals that buffalo-keeping and milk sales are increasing the well-being of many households, while at the same time creating new inequalities in gender roles and responsibilities, greater inequities between Brahmin and Tamang residents in Ghusel, and placing pressures on the ecosystem for increased supplies of fodder and fuelwood. Evidence suggests that there is critical, need for attention to the social, and particularly gender-based, implications of maintaining livestock for milk sales and to the ecological underpinnings of this livelihood system.     

Chiral Separation of G‐type Chemical Warfare Nerve Agents via Analytical Supercritical Fluid Chromatography

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G‐type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical‐scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(–) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(–) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. Chirality 26:817–824, 2014. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc.     

In vitro studies of the rabbit immune system. IV. Differential mitogen responses of isolated T and B cells.

The mitogenic responses of separated rabbit lymphocyte populations functionally analogous to mouse T and B cells have been tested in vitro. Purified T cells were prepared by passage over nylon wool (NW) and purified B cells prepared by treatment with antithymocyte serum and complement (ATS + C). ATS + C kills 70% of peripheral blood lymphocytes (PBL's) and 50% of the spleen cells while passage over NW yields 40% of the applied PBL's and 5–23% of the applied spleen cells. NW-purified T cells from the spleen or PBL's respond fully to concanavalin A (Con A) but have a reduced response to phytohemaglutinin (PHA) and little or no response to goat anti-rabbit immunoglobulin (anti-Ig). PBL's that survive ATS + C (B cells) are stimulated by anti-Ig but not by Con A or PHA. B cells purified from spleen do not respond to Con A or PHA but will respond to anti-Ig under appropriate conditions. A full spleen B-cell response to anti-Ig required removal of Ig produced by the cultures that blocked anti-Ig stimulation. It is concluded that, for rabbit lymphocytes, Con A and PHA are primarily T-cell mitogens and that anti-Ig is primarily a B-cell mitogen. However, the mitogen response of unfractionated PBL or spleen cell populations indicates an overlap in reactivity. This could be due to cells sharing T and B properties, alteration of cell populations by the fractionation procedures used, or recruitment of one population in the presence of a mitogenic response of the other population.     

邻苯二甲酸二丁酯对翡翠贻贝抗氧化酶及脂质过氧化水平的影响

实验室条件下,研究了不同浓度邻苯二甲酸二丁酯(DBP)长期胁迫(15 d)对翡翠贻贝内脏团和外套膜抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT)及脂质过氧化(LPO)水平(以MDA含量表示)的影响,以及受胁迫翡翠贻贝在清洁海水中恢复阶段上述生化指标的变化特征.结果表明:胁迫阶段,0.5和2.5 mg.L-1DBP下翡翠贻贝内脏团SOD活性表现为先抑制后逐渐恢复,12.5和62.5 mg.L-1下则持续受到显著抑制;不同浓度组CAT活性均明显被抑制.LPO水平明显升高.外套膜中,2.5 mg.L-1下SOD活性受到持续诱导,其他浓度组则先被抑制,后随曝露时间延长逐渐被诱导;各浓度组CAT的变化波动较大,没有明显规律;而LPO水平明显升高.净化恢复阶段,12.5和62.5 mg.L-1DBP胁迫下的内脏团SOD和CAT活性恢复较慢,其LPO水平随时间延长逐渐恢复至对照组水平;外套膜中SOD活性呈持续升高趋势,CAT活性和LPO水平则随时间延长恢复到对照组水平.     

多马胺能药物对鲇鱼促性腺激素（GtH）分泌活动的影响

以珠江流域鲇鱼（silurus asotus)为实验材料,研究了多巴胺（DA）能药物（DA及其D－2型受体拮抗物 ,DOM）对鲇鱼促性腺激素（GtH)释放的影响,结果表明,在性腺发育的各个时期,单独注射DOM（5ug/g)均不能显著提高鲇鱼血液基础GtH水平,当DOM与LHRH－A联合注射时能显著增强LHRH－A刺激GtH释放的作用;DA只能抑制GnRH诱导的GtH释放,对基础GtH释放无抑制作用,这种生殖内分泌调节方式与鲇形目的革胡子鲇（Clarias gariepinus)和大鳍Hu（Mystus macropterus)相似,而与鲤形目的鲁科（Cyrpindiae)鱼类不同。     

X-ray induction of dominant lethals in late spermatids and mature spermatozoa of Drosophila melanogaster: the role of oxygenation

The role of oxygenation in determining the sensitivity to the induction of dominant lethals was examined in late spermatids and mature spermatozoa of Drosophila melanogaster. 0–2-h-old or 7-day-old Oregon-K males were irradiated with different X-ray exposures in nitrogen, air or in oxygen and the frequencies of dominant lethals induced in these stages were studied. The results obtained confirm and extend Sobels' earlier observations and the interpretation derived therefrom namely, that under normal conditions in air, mature spermatozoa are characterised by a higher degree of oxygenation than late spermatids and this difference is sufficient to explain the differential response of these stages. Similar Oxygen-Enhancement-Ratios(OERs) (of about 2) were obtained for both the cell stages. The present data also revealed that late spermatids are significantly less sensitive than mature spermatozoa to the X-ray-induction of dominant lethals in a nitrogen atmosphere. A plausible mechanism is suggested to explain this observation.