急性胰腺炎几项实验诊断指标的比较

目的为了探讨血、尿淀粉酶,淀粉酶清除率与肌酐清除率比值（ACCR）以及尿胰蛋白酶原-2（Tpg-2）测定对急性胰腺炎（AP）的临床诊断价值。方法对67例急性胰腺炎患者,42例非胰腺炎急腹症患者和60例健康体检人员进行血、尿淀粉酶,血、尿肌酐及尿胰蛋白酶原-2测定。结果急性胰腺炎尿胰蛋白酶原-2诊断特异度和敏感度最高,分别为95．2％、95．5％,其次是淀粉酶清除率与肌酐清除率比值,其特异度和敏感度分别为85．7％、92．5％,血淀粉酶（Samy）特异度和敏感度分别为78．6％、80．6％,尿淀粉酶（Uamy）特异度和敏感度分别为69．0％、73．1％。结论尿胰蛋白酶原-2和淀粉酶清除率与肌酐清除率比值是目前诊断急性胰腺炎较好的早期指标,优于血尿淀粉酶。     

A comparison of single plasma sample methods to estimate renal clearance using 99mTc‐ethylenedicysteine and 99mTc‐mercaptoacetyltriglycine

Several single sample methods for determination of ^99mTc‐mercaptoacetyltriglycine (MAG3) clearance are being used clinically. Kabasakal et al. proposed a similar formula for ^99mTc‐ethylenedicysteine (EC). This study was performed to compare his method with Bubeck et al. formula for ^99mTc‐MAG3 already in use. Twenty‐eight subjects divided in two groups were registered which included 22 patients with various renal diseases (group‐I) and six normal volunteers (group II). All subjects were studied twice using both the radiopharmaceuticals. The images and renogram parameters, that is T_MAX and T_1/2 of both the agents, were similar in all the subjects. The clearance of the ^99mTc‐EC was however considerably higher than ^99mTc‐MAG3 in both the groups (mean ± SEM =279 ± 14 ml min^?1/1·73 m² versus 177 ± 15 ml min^?1/1·73 m² in group‐I and 377 ± 11·90 ml min^?1/1·73 m² versus 238 ± 8·23 ml min^?1/1·73 m² in group II). This difference was more pronounced in cases with reduced renal functions. Among the Effective Renal Plasma Flow (ERPF) values determined from EC and MAG3 clearances in six normal volunteers, four cases only in MAG3 had ERPF below the lower limit. This study has demonstrated superiority of single sample method for ^99 mTc‐EC clearance over its analogous method for ^99mTc‐MAG3.     

肾小球滤过率智能检测分析系统的研制及临床应用研究

目的 研制肾小球滤过率(GFR)智能检测分析系统(GFRBMAS),并探讨其检测GFR的临床应用价值.方法 采用VB 6.0软件编程,并配置好GFRBMAS.采用99锝m-二:乙烯三胺五乙酸(99Tcm-DTPA)清除率准确测定79例不同疾病住院患者GFR(Tc-GFR),检测并比较GFRBMAS与日立7170S全自动生化仪所测得的血清肌酐(SCr)、尿素氮(BUN)、血尿酸(Uric)、血清钙(Ca)和血清磷(P)值,同时以GFRBMAS、Robert公式测定或测算GFR(GFRBMAS-GFR、Robert-GFR),以Cockcroft/Gault公式计算内生肌酐清除率(CG-CCr),所得数据进行相关分析与对比研究.结果 两种检测方法测得的SCr、BUN、Uric、Ca、P值差异均无统计学意义(P均＞0.05),且两者均呈显著正相关(P均＜0.01).肾功能正常组和不全组Robert-GFR、CG-CCr值均明显小于Tc-GFR值,差异有统计学意义(P均＜0.01),而GFRBMAS-GFR值与Tc-GFR值相近.相关分析显示,肾功能不全组及正常组GFRBMAS-GFR、Robert-GFR、CG-CCr与Tc-GFR值均呈显著正相关,与SCr、BUN均呈负相关(P＜0.05或P＜0.01).结论 GFRBMAS-GFR、Robert-GFR、CG-CCr均能在一定程度上准确反映GFR,而GFRBMAS-GFR可代替Tc-GFR应用于临床.     

Exaggerated natriuretic response to isotonic volume expansion in hypertensive renal transplant recipients: evaluation of proximal and distal tubular reabsorption by simultaneous determination of renal plasma clearanceof lithium and 51Cr-EDTA

In fourteen hypertensive and fourteen normotensive renal transplant recipients, and in a group of thirteen healthy controls, changes in natriuresis, glomerular filtration rate (GFR), and tubular reabsorption of sodium were determined in relation to intravenous infusion of 2 mmol isotonic sodium chloride per kg body weight. An exaggerated natriuresis was demonstrated in the hypertensive renal transplant recipients. This new finding indicates that the augmented natriuresis following plasma volume expansion, which is a characteristic finding in subjects with arterial hypertension, is not mediated by the renal nerves. Investigation of the tubular reabsorption rates of sodium by simultaneous determination of the renal clearance of 51Cr-EDTA and lithium showed that in the hypertensives the changes in tubular handling of sodium were different from those registered in the normotensive subjects. The increased sodium excretion in the hypertensive renal transplant recipients was caused by an increased output of sodium from the proximal tubules which was not fully compensated for by an increased distal reabsorption. Whether this increased delivery of sodium to the distal segments was caused by changes in GFR or in the proximal tubular reabsorption of sodium could not be clarified in the present study and warrants further investigations.     

小剂量多巴胺和多巴酚丁胺对非少尿型肾功能衰竭的影响

目的探讨小剂量多巴胺和多巴酚丁胺对非少尿型肾功能衰竭患者肾功能的影响。方法29例血流动力学稳定的非少尿型肾功能衰竭患者,采用随机数字表法选择给药顺序,对照组给予质量分数为5%的葡萄糖,多巴胺组给予多巴胺5μg·kg-1·min-1,多巴酚丁胺组给予多巴酚丁胺5μg·kg-1·min-1;用微量注射泵持续静脉泵入一种药物4h后更换另一种药物,为消除上一种药物对各项监测指标的影响,每种药物更换前间隔1h再进入下一种药物观察阶段。每给一种药物后用SwanGanz导管监测患者的血流动力学指标变化;同时取血、尿测定肾功能指标。结果与对照组相比多巴胺、多巴酚丁胺能明显增加心率(HR)、心排血指数(CI)、尿量和肌酐清除率(CCr),差异均有显著性;多巴胺较多巴酚丁胺能更加明显地增加尿量和钠排泄分数(FeNa),差异均有显著性;而多巴酚丁胺增加CCr的程度与多巴胺比较差异无显著性。结论多巴胺和多巴酚丁胺对非少尿型肾功能衰竭均有增加HR、CI、尿量、FeNa和CCr的作用,多巴胺较多巴酚丁胺增加尿量和FeNa更明显,多巴酚丁胺增加CCr与多巴胺相比差异无显著性。     

Arterio-venous concentration difference of [51Cr]EDTA after a single injection in man. Significance of renal function and local blood flow

Summary. The present investigation was undertaken in order to study (1) the difference in arterial (C_a) and venous (C_v) concentration of [⁵¹Cr]EDTA (ethylenediaminetetra-acetate) after a single intravenous injection, (2) the impact of different physiological variables on this difference, and (3) the error introduced in the measurement of renal plasma clearance and total plasma clearance by using venous blood samples instead of arterial. In 13 patients with GFR ranging from 29 to 150 ml min^-1, C_a was higher than C_v immediately after the injection. After mean 38 min (range 12–82 min) the two curves crossed, and 180–300 min post-injection (p.i.) C_v was 5·9% higher than C_a (range 0·5–13·9%, P<0·001). The more reduced renal function, the smaller was the concentration difference. The areas under the arterial and the venous plasma concentration curves did not differ significantly at either 0–∞ or 0–300 min p.i., whereas the venous area 0–100 min p.i. underestimated the arterial area in the same period by 4·1% (P<0·05). In a computer simulation model, variation in the forearm capillary permeability–surface area product did not have any significant influence on the C_v–C_a difference, whereas the difference was very sensitive to even small changes in forearm blood flow within the physiological range. For measurement of renal plasma clearance it is recommended to use one long period: from the time of injection until 300 min p.i. or longer. If the clearance period is too short, the use of venous samples will overestimate the true renal clearance. Plasma clearance determined by venous and arterial blood samples does not differ significantly as long as the concentration is followed from the time of injection and a long period is applied. When simplified plasma clearance techniques are used, different results may be obtained from venous and arterial samples. The simplified techniques using venous blood samples—which usually include some empirical corrections—should be sufficiently reliable in daily clinical practice provided the forearm blood flow is reasonably high, e.g. exposure to cold should be avoided.     

计算法测定肾小球滤过率的临床应用价值

目的 :探讨采用 WCP公式计算方法测定肾小球滤过率 (GFR)的临床应用价值。方法 :采用 99m Tc DTPA清除率测定 6 6例不同疾病住院患者 GFR(Tc GFR) ,并测血清肌酐 (SCr)及尿素氮 (BU N) ,同时以 WCP公式、Robert公式计算 GFR(WCP GFR,Robert GFR) ,以 Cockcroft/ Gault公式计算内生肌酐清除率 (CG CCr) ,所得数据进行对比研究及相关性分析。结果 :除肾功能正常者 CG CCr与 BU N无显著相关外 ,肾功能不全及肾功能正常者的 WCP GFR、Robert GFR、CG CCr均分别与 Tc GFR呈显著正相关(P均 <0 .0 1) ,与 BU N、SCr呈显著负相关 (P<0 .0 1或 P<0 .0 5 ) ;与 Robert GFR、CG CCr比较 ,WCPGFR始终与 Tc GFR最接近 (P均 >0 .0 5 ) ;WCP GFR、Robert GFR、CG CCr与 Tc GFR的平均差绝对值逐渐增大 ,三者间差异显著 (P均 <0 .0 5 )。结论 :WCP GFR、Robert GFR、CG CCr均能在一定程度上准确反映 GFR,而以 WCP GFR更准确 ,且简便、快速、安全而廉价 ,可代替 Tc GFR应用于临床     

Metabolic clearance rate of immunoreactive vasopressin in man

Abstract. Metabolic clearance of synthetic arginine vasopressin (AVP) has been measured in sixteen healthy subjects and ten uraemic patients on maintenance haemodialysis. Plasma AVP was measured using a specific radioimmunoassay at different intervals after a single injection of 2 μg AVP. The theoretical curve which fitted best with the disappearance curve was the sum of two exponentials in twenty-two subjects and of three exponentials in the other four. Metabolic clearance rate and the volume of fast initial distribution were 287·1 ml min^-1 (m²)^-1 and 219·3 ml/kg b.w., respectively, in normal subjects. Metabolic clearance rate was considerably lower in the uraemic group. This emphasizes the role of kidneys in the degradation of AVP and may account, at least in part, for the higher basal plasma value of this hormone observed in uraemic patients.     

99mTc-MAG3 kinetics in the normal pig. A comparison to 131I-OIH and 125I-iothalamate after single injection and during continuous infusion

Summary. An invasive comparative study of some pharmacokinetic aspects of ^99mTc-mercaptoacetyltriglycine (MAG3), ¹³¹I-orthoiodohippurate (OIH), and ¹²⁵I-iothala-mate (iothalamate) was performed in six pigs 0–150 min after a simultaneous single injection (SI) and during a subsequent 90 min of continuous infusion (CI). The total plasma clearance and the renal clearance of MAG₃ were about 75% that of OIH. The renal clearance of MAG₃ was about 2¹/₂ times the glomerular filtration rate. The distribution volume of MAG₃ was 71% that of iothalamate and only 47% that of OIH. There was a significant hepatic plasma clearance of MAG₃ of 5.9 ml min^-1 and 3.9% of the injected dose was excreted in the bile. HPLC analysis revealed that technetium was excreted in urine and Me mainly labelled to MAG₃. The average red blood cell (RBC) binding after single injection/during continuous infusion was 1.0%/2.3% for MAG₃, 13.5%/9.0% for OIH, and 3.1%/5.3% for iothalamate. The binding of OIH to RBC in arterial blood increased from 8% at 1 min post-injection to 21% at 150 min post-injection. The RBC binding was higher in the renal vein, indicating incomplete back diffusion from RBC to plasma. The protein binding was 90% for MAG₃, 49% for OIH and 16% for iothalamate. The renal plasma extraction of MAG₃ was constant but significantly smaller after SI (0.54) than during CI (0.62). Following SI, the renal plasma extraction of OIH decreased continuously from 0.85 to 0.52, 3.150 min post-injection. On the average there was no significant difference in renal plasma extraction after SI and during CI of either OIH (0.72 versus 0.77) or iothalamate (0.26 versus 0.27). It is concluded that MAG₃ is preferential to OIH as a tracer for renal function studies using a single injection technique mainly due to the constant renal extraction of MAG₃.     

ICU危重患者血乳酸变化水平与预后晌关系探讨

目的：探讨重症监护病房（ICU）内血乳酸增高的危重病患者的乳酸水平变化情况与7d、28d预后的关系。方法：收集ICU内动脉血乳酸水平升高的患者共133例,比较7d、28d的病死率。按7d、28d存活或死亡情况分组观察一般资料、乳酸指标（／kICU乳酸高值,8h、24h乳酸清除率）、住ICU天数、急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分。分别按入院乳酸高值分组、按8h、24h乳酸清除率分组、按高乳酸时间分组比较各组患者的一般资料、APACHEⅡ评分、7d和28d病死率。结果：住ICU乳酸升高患者28d病死率较7d病死率明显升高（P〈0.01）。7d、28d死亡组患者乳酸值、APACHEⅡ评分均显著高于生存组（P〈0．05、0.01）,乳酸8。h清除率、24h清除率均显著低于生存组（P〈0.01）。严重乳酸酸中毒组7d病死率、APACHEⅡ评分明显高于高乳酸血症组（P〈O．01、0．05）,28d病死率无明显差异;而高乳酸血症组与乳酸酸中毒组之间观察值均无明显差异。各高清除率组与低清除率组比较,7d、28d病死率均明显降低（P〈O．01）,各中、低清除率组之间比较仅24h低清除率组28d病死率较中清除率组明显升高（P〈O．01）,其余各观察值均无明显差异。高乳酸时间〉8hell、〉24h组7d、28d病死率均较〈8h组明显升高（P〈O．01）,且28d病死率较7d病死率组明显升高（P〈O．05）。结论：ICU病房内血乳酸水平增高的危重病患者28d的总体病死率比7d病死率明显增加。人院血乳酸水平、乳酸清除率、高乳酸时间均是评估患者预后的良好指标,而且随着高乳酸时间的延长,28d病死率比7d病死率明显增高,在8h内将血乳酸降至正常范围内可能改善危重患者的预后。     

光抑素C与血肌酐对2型糖尿病患者肾小球滤过功能评价比较

目的 比较光抑素C(Cystatin C)和血清肌酐及8小时肌酐清除率，评价其对2型糖尿病患者肾小球滤过率(GFR)的判断价值。方法 选择80例2型糖尿病患者，检测其血肌酐、肌酐清除率、尿微量白蛋白排泌率(UAER)及Cystatin C水平，同时通过^99mTc-DTPA排泌率，应用Gates法计算GFR。结果 Cystatin C水平随GFR下降逐渐升高。相关性分析示Cystatin C与GFR呈相关性(r=-0．663，p=0．000)，明显高于肌酐(r=-0．444，P=0．009)及8小时肌酐清除率(r=0．300，P=0．000)。ROC曲线分析示Cystatin C具有更大的曲线下面积(AUC)，敏感性(82％)、特异性(96％)均好，而肌酐特异性好(98％)、敏感性差(20％)，8小时肌酐清除率敏感性(68％)、特异性(79％)均不理想。Cystatin C诊断精确性(80％)明显高于肌酐(63％)。结论 Cystatin C是反映GFR的更敏感指标，可更早、更准确地反映2型糖尿病患者GFR的变化。     

Modulation of the glucagon-like peptide-1 receptor signaling by naturally occurring and synthetic flavonoids

The glucagon-like peptide 1 receptor (GLP-1R) is a promising target for the treatment of type II diabetes mellitus because of its role in metabolic homeostasis. In recent years, difficulties with peptide therapies have driven the search for small-molecule compounds to modulate the activity of this receptor. We recently identified quercetin, a naturally occurring flavonoid, as a probe-dependent, pathway-selective allosteric modulator of GLP-1R-mediated signaling. Using Chinese hamster ovary cells expressing the human GLP-1R, we have now extended this work to identify the structural requirements of flavonoids to modify GLP-1R binding and signaling (cAMP formation and intracellular Ca(2+) mobilization) of each of the GLP-1R endogenous agonists, as well as the clinically used exogenous peptide mimetic exendin-4. This study identified a chemical series of hydroxyl flavonols with the ability to selectively augment calcium (Ca(2+)) signaling in a peptide agonist-specific manner, with effects only on truncated GLP-1 peptides [GLP-1(7-36)NH(2) and GLP-1(7-37)] and exendin-4, but not on oxyntomodulin or full-length GLP-1 peptides [GLP-1(1-36)NH(2) and GLP-1(1-37)]. In addition, the 3-hydroxyl group on the flavone backbone (i.e., a flavonol) was essential for this activity, however insufficient on its own, to produce the allosteric effects. In contrast to hydroxyl flavonols, catechin had no effect on peptide-mediated Ca(2+) signaling but negatively modulated peptide-mediated cAMP formation in a probe-dependent manner. These data represent a detailed examination of the action of different flavonoids on peptide agonists at the GLP-1R and may aid in the development of future small molecule compounds targeted at this receptor.     

血清半胱氨酸蛋白酶抑制剂C与平均肾小球体积的相关性研究

目的 研究血清半胱氨酸蛋白酶抑制剂C（Cys C）与平均肾小球体积（MGV）的相关性,以寻求对肾小球滤过翠表达的理想检验指标。方法 应用颗粒增强免疫透射比浊法测定31例不同肾脏疾病肾活检患者的血清Cys C浓度,同时用体视学方法测定MGV。结果 Cys C与MGV明显相关（r=0．715,P〈0．01）,与内生肌酐清除率（Ccr）显著相关（r=-0．819,P〈0．01）;Ccr与MGV也明显相关（r=-0．609,P〈0．01）;血肌酐（Cr）与MGV之间的r为0．546（P〈0．05）。结论 血清CysC与MGV的改变明显相关。     

血清半胱氨酸蛋白酶抑制剂C与平均肾小球体积的相关性研究

目的研究血清半胱氨酸蛋白酶抑制剂C(CysC)与平均肾小球体积(MGV)的相关性,以寻求对肾小球滤过率表达的理想检验指标。方法应用颗粒增强免疫透射比浊法测定31例不同肾脏疾病肾活检患者的血清CysC浓度,同时用体视学方法测定MGV。结果CysC与MGV明显相关(r=0.715,P<0.01),与内生肌酐清除率(Ccr)显著相关(r=-0.819,P<0.01);Ccr与MGV也明显相关(r=-0.609,P<0.01);血肌酐(Cr)与MGV之间的r为0.546(P<0.05)。结论血清CysC与MGV的改变明显相关。     

Methods for studying naturally occurring human pain and their analogues

Methods for investigating human pain have been developed over the last 100 years. Typically, researchers focus on people with clinical pain, or on healthy participants undergoing laboratory-controlled pain-induction techniques focussed mostly on exogenously generated skin nociception. Less commonly investigated are acute pain experiences that emerge naturally. Six common painful complaints were identified: headache, muscular pain, visceral pain, menstrual pain, dental pain, and pain associated with upper respiratory tract infection. Methods used to recruit participants with the natural occurrence of each pain complaint were identified, and features of their use reviewed. Also reviewed were experimental analogues designed to mimic these pains, with the exception of menstrual pain. Headache and menstrual pain appear to be most effectively researched in their naturally occurring form, whereas muscle and dental pain may be more easily induced. Upper respiratory tract infection and abdominal pain provide further challenges for researchers. Summary guidance is offered, and directions for methods development outlined.     

Enhancement of cyclosporin A induced hepato- and nephrotoxicity by glutathione depletion

Abstract The role of glutathione in cyclosporin A (cyclosporin) hepato- and nephrotoxicity has not been clarified yet. The hypothesis that a glutathione deficit enhances the hepato- and nephrotoxicity of cyclosporin was tested in an animal model. Glutathione depletion was achieved by administration of diethyl maleate (DEM). Adult Sprague Dawley rats were divided into four groups (A–D; n≥ 8) and treated for 8 d as follows: group A, glucose 5% (0·4 ml kg^-1, i.p.) + 3 h later olive oil (0·5 ml kg^-1, oral); group B, DEM (0·4 ml kg^-1, i.p.) + 3 h later olive oil (0·5 ml kg^-1, oral); group C, glucose 5% (0·4 ml kg^-1, i.p.) + 3 h later cyclosporin (50 mg kg^-1, oral); group D, DEM (0·4 ml kg^-1, i.p.) + 3 h later cyclosporin (50 mg kg^-1, oral). Cyclosporin alone increased bilirubin concentration from 1·0 ± 0·6 μmol l^-1 to 8·4 ± 1·9 μmol l^-1 (P < 0·05) without changing transaminases. In glutathione depleted rats cyclosporin caused a further elevation of serum bilirubin up to 23·4 ± 5·5 μmol l^-1. This was accompanied by a 50% increase of serum glutamic oxaloacetic transaminase (GOT). Cyclosporin alone significantly decreased creatinine clearance to 50% of controls (P < 0·05). Cyclosporin treatment following glutathione depletion resulted in a further decline of creatinine clearance to 22% of controls. DEM had no effect on kidney or liver function. In conclusion glutathione depletion increases the susceptibility to cyclosporin-induced liver and kidney injury. The results support the hypothesis that sufficient cellular glutathione concentrations may be important to prevent cyclosporin-induced hepato- and nephrotoxicity.     

A comparison of antinociception induced by foot shock and morphine

We compared the antinociception produced by brief intermittent foot shock (0.8-1.0 mA for 20 sec) and morphine by measuring the peak and duration of the effect, the consequences of spinalectomy and the sensitivity to antagonism by naloxone and d- and l-pentazocine and cyclazocine. Foot shock produced a peak antinociception (FSIA) equal to 10 mg/kg of morphine but the duration of FSIA was much shorter. Naloxone antagonized FSIA but a much larger dose (10 mg/kg) was required than for antagonism of morphine. The d-isomers of pentazocine and cyclazocine reduced FSIA but had no effect on morphine antinociception, whereas the l-isomers increased the peak and duration of FSIA and antagonized morphine-induced antinociception. Spinalectomy, which is known to block morphine antinociception, also blocks FSIA. Foot-shock stress did not produce an increase in tail-flick latency in morphine or methadone-tolerant animals demonstrating cross-tolerance between FSIA and morphine and methadone. The similarities between FSIA and morphine-induced antinociception suggest that similar opioid systems may be involved in both. However, the differences suggest that antinociception produced by brief FSIA involves a nonopiate as well as an opiate mechanism, perhaps with multiple opioid receptor sites having different affinities for the isomers of the antagonists.     

斜侧卧位微通道经皮肾镜取石术治疗马蹄肾肾结石的疗效

目的探讨斜侧卧位微通道经皮肾镜取石术治疗马蹄肾肾结石的疗效。方法回顾性分析34例马蹄肾肾结石患者行斜侧卧位微通道经皮肾镜钬激光碎石取石术的临床资料(手术时间、出血量、结石清除率、并发症等)。结果所有患者均手术成功,其中平均手术时间为(57±21)min,术中平均出血量为(102±85)m L,术中并发症发生率为5.9%(2/34)。术后1周复查结石清除率为91.2%(31/34),残留结石患者术后行ESWL及输尿管软镜手术,1个月后复查结石清除干净。所有患者均随访3~12月,未见结石复发及相关并发症发生。结论斜侧卧位微通道经皮肾镜取石术治疗马蹄肾结石安全、有效。     

Antigens of leukemias induced by naturally occurring murine leukemia virus: their relation to the antigens of gross virus and other murine leukemia viruses

Leukemias can be induced in W/Fu inbred rats by neonatal inoculation of normal thymus cells of C58 mice. These leukemias are not transplantable to C58 mice or to adult W/Fu rats, but they can be kept in passage in W/Fu rats aged 0 to 7 days. Adult W/Fu rats inoculated repeatedly with these isogenic leukemias produce cytotoxic and precipitating antibodies. These antisera are of particular value in the analysis of the antigens of leukemia cells and of leukemia viruses because their mode of preparation precludes the formation of antibody against any normal constituents of the cell. Analysis based on the cytotoxic test indicates the presence of 2 distinct cell surface antigens in leukemias induced by Passage A Gross virus or occurring spontaneously in mice of high-incidence strains. All leukemias and other tissues known to contain G (Gross) leukemia antigen have both determinants, but certain leukemias of low-incidence strains have only 1 of them and so were previously classified G-. Immunoprecipitation with these antisera reveals the presence of a cellular antigen common to G+ cells and absent from G- cells; the same antigen can be demonstrated in ether-treated Gross virus, but not in intact virus. This antigen is present also in ether-treated preparations of the Friend, Moloney, and Rauscher leukemia viruses, but not in Bittner (mammary tumor) virus. Thus it may be regarded as a group-specific antigen of murine leukemia viruses, in contrast to the type-specific cellular antigens demonstrable by the cytotoxic test. Four additional antigens associated with leukemias induced by wild-type Gross virus have been demonstrated by immunoprecipitation, but their relation to viral and cellular antigens has not been determined.