氯乙烯染毒大鼠代谢酶活性的动态变化和肝损伤

目的　研究氯乙烯 (VCM)染毒大鼠代谢酶活性和肝损伤生化指标的动态变化 ,以及大鼠肝脏的病理改变 ,探索血清、肝组织VCM代谢酶活性变化与肝脏损伤间的关系。方法　大鼠染毒 12周 ,分别在第 3、6、9和 12周处死动物 ,代谢酶活性测定采用分光光度法 ;肝功能生化指标用自动生化分析仪测定 ;光镜、电镜检测染毒大鼠肝组织病理改变。结果　VCM代谢酶ALDH、CYP2E1和GSTs活性随染毒时间和剂量的增加发生改变 ,差异具有统计学意义。ALP与血清ADH的活性呈负相关 (r=- 0 6 4 9) ;血清GSTs、ADH的活性分别与肝组织中GSTs、ADH活性呈正相关 (r- =0 4 39、0 5 0 8,P <0 0 5 )。结论　VCM致肝损伤程度可能与代谢酶活性有关 ,肝脏代谢酶变化是VCM引起机体损害的早期较敏感指标。     

大鼠肝细胞色素P4502E1酶活性的气相色谱法测定

本文报告了用气相色谱法测定大鼠肝细胞色素Ｐ４５０２Ｅ１的酶活性。在一定的实验条件下，使丁醇在微粒体中被氧化为丁醛，用顶空气相色谱法测定产生的丁醛量，并测定肝微粒体中的蛋白质及细胞色素Ｐ４５０总量，可算出细胞色素Ｐ４５０催化丁醇氧化的速率，实验表明，乙醇诱导的细胞色素Ｐ４５０２Ｅ１明显增大了丁醇氧化的速率，而其他典型诱导剂诱导的细胞色素Ｐ４５０异构酶不增大丁醇氧化速率，所以，细胞色素Ｐ４５０催化丁醇氧化的速率可作为判断细胞色素Ｐ４５０２Ｅ１酶活性的指标。     

氯乙烯致大鼠DNA损伤与肝代谢酶活性动态变化的研究

[目的]研究氯乙烯(VC)对大鼠肝细胞和外周血淋巴细胞DNA的损伤作用，及对VC代谢酶[谷胱甘肽硫转移酶(GST)、细胞色素P4502E1(CYP2E1)、乙醇脱氢酶(ADH)和乙醛脱氢酶(ALDH)]活性的影响；探索VC所致损伤的早期敏感检测指标。[方法]大鼠染毒12周，分别在第3、6、9和12周处死动物，DNA损伤采用单细胞凝胶电泳(彗星试验)法，代谢酶活性测定采用分光光度法。[结果]彗星细胞数目随染毒剂量和染毒时间的增加而增加，肝细胞DNA损伤细胞百分率第12周中剂量组和高剂量组分别为12.38％和17.88％，外周血淋巴细胞DNA损伤细胞百分率第3周高剂量组为7．33％，第12周中剂量组和高剂量组分别为16．25％和28、25％，均显著高于相应对照组，彗星细胞发生率与VC染毒剂量间存在显著相关关系。ALDH和CYP2E1活性随染毒时间和染毒剂量的增加发生改变，差异具显著性。肝细胞DNA损伤与CYP2EI活性相关。[结论]VC可导致肝细胞和外周血淋巴细胞DNA发生损伤，且存在剂量．反应和时间一效应关系；VC致肝细胞DNA损伤与CYP2E1代谢酶活性相关。彗星细胞率可作为VC所致肝脏损伤的早期检测指标。     

维生素E对大鼠肝线粒体酶活性的影响

目的观察维生素E（VE）补充对大鼠肝线粒体ATP酶和抗氧化酶活性的影响。方法Wistar大鼠随机分成4组，对照组、VE1、VE2和VE3干预组；对照组给予普通饲料，3个干预组均喂饲添加维生素E的饲料，剂量分别为335，1340，5025mg／kg饲料，喂养10周后，摘取肝脏提取线粒体，测定Na^＋-K^＋-ATP酶、Ca2^＋-Mg^＋-ATP酶、谷胱甘肽过氧化物酶（GSH—Px）、超氧化物歧化酶（SOD）的活性及丙二醛（MDA）的含量。结果VE1组与对照组相比，SOD、GSH—Px、Na^＋-K^＋-ATP酶、Ca2^＋-Mg2^＋-ATP酶活性显著升高（P〈0．05），MDA水平显著降低（P〈0．05）。VE2、VE3组与对照组相比未见改善。VE2、VE3和VE1组相比，SOD、GSH—Px、Na^＋-K^＋-ATP酶、Ca2^＋-Mg^＋-ATP酶活性显著降低（P〈0．05），MDA水平显著升高（P〈0．05）。结论补充适量VE（335mg／kg）能显著增强大鼠肝线粒体ATP酶活性及氧化能力；较高剂量VE；（1340，5025mg／kg）组未能改善大鼠肝线粒体ATP酶活性及抗氧化能力。     

Gender-related differences in mouse hepatic ethanol metabolism

The effect of an acute oral load of 2 g ethanol/kg body weight was studied in a group of male and female 10-wk-old C3H/HeNCrj (C3H/He) mice to investigate gender change throughout differences of the hepatic ethanol metabolism of mice. The following parameters were measured in the serum from 0 h to 3 h after the start of the experiment: ethanol, acetaldehyde, and acetate. Their concentrations in the serum in female mice tended to show lower levels than in male mice. In female mice, the concentration of ethanol at 1 h and the concentration of acetate at 1 h, 2 h, and 3 h after ethanol administration showed significantly lower levels than in male mice. Ten-week-old male and female C3H/He mice were subcutaneously injected 50 microg/kg body weight beta-estradiol and 1.45 mmol/kg body weight testosterone propionate (testosterone) in olive oil, respectively, and changes in the activity of enzymes related to the hepatic ethanol metabolism of mice were examined at 24 h after the administration of sex hormones. The activity of the cytosolic alcohol dehydrogenase (ADH) and microsomal aniline hydroxylase (ANH) and the low Km, high Km and total aldehyde dehydrogenase (AlDH) activities in the mitochondrial, the cytosolic, and the microsomal fraction of the liver were higher. Moreover, the density of the band of CYP2E1 in the microsome in female mice was stronger than in male mice, and in the microsomal fraction of the liver, the total content of cytochrome P-450 (CYP) and ethoxyresorufin O-dealkylase (EROD) activity in male mice showed significantly higher values than in female mice. The density of the band of CYP2E1 and the three activities of AlDH in the hepatic mitochondrial fraction of male mice increased significantly under treatment with beta-estradiol. The three activities of AlDH of the cytosolic fraction of the liver in female mice significantly decreased under treatment with testosterone. The present findings suggested that in C3H/He mice livers, the rate of ethanol metabolism is faster in females than in males, and the enzymes related to ethanol metabolism are controlled by testosterone or beta-estradiol. It is suggested that ethanol and its metabolite disappear faster from the serum of female mice than from the serum of male mice because the activities of hepatic enzymes related to ethanol metabolism are higher in female mice than in male mice. C3H/He mice, hepatic ethanol metabolism, gender different, ADH, AlDH     

大肠埃希菌感染后家蝇幼虫血清中3种酶活性的变化

目的探讨大肠埃希菌感染对家蝇3龄幼虫血清中3种酶活性的影响。方法（1）用比色法分别测定感染后不同时间家蝇3龄幼虫血清中酸性磷酸酶（ACP）及过氧化氢酶（CAT）活性的变化。（2）用聚丙烯酰胺凝胶电泳法测定感染后不同时间家蝇3龄幼虫血清中二酚氧化酶（DPO）活性的变化。结果（1）大肠埃希菌感染后各时间组血清中ACP及CAT活性显著高于对照组（P〈0．01）。其中ACP及CAT活性分别在感染8和16h达高峰，其值分别为（107．9±3．5）u／100ml和（174．6±4．7）u／ml，然后逐渐下降。（2）家蝇幼虫体内存在DPO，且感染后4hDPO活性上升，16h达高峰，其值为98805．39，之后下降。结论大肠埃希菌感染后家蝇3龄幼虫血清中ACP、CAT及DPO活性均增强，提示这3种酶在防御微生物感染过程中发挥了重要作用。     

Safety and immunogenicity of HCV E1E2 vaccine adjuvanted with MF59 administered to healthy adults

Background

Hepatitis C virus (HCV) causes chronic liver disease that often leads to cirrhosis and hepatocellular carcinoma. In animal studies, chimpanzees were protected against chronic infection following experimental challenge with either homologous or heterologous HCV genotype 1a strains which predominate in the USA and Canada. We describe the first in humans clinical trial of this prophylactic HCV vaccine.

Methods

HCV E1E2 adjuvanted with MF59C.1 (an oil-in-water emulsion) was given at 3 different dosages on day 0 and weeks 4, 24 and 48 in a phase 1, placebo-controlled, dose escalation trial to healthy HCV-negative adults.

Results

There was no significant difference in the proportion of subjects reporting adverse events across the groups. Following vaccination subjects developed antibodies detectable by ELISA, CD81 neutralization and VSV/HCV pseudotype neutralization. There were no significant differences between vaccine groups in the number of responders and geometric mean titers for each of the three assays. All subjects developed lymphocyte proliferation responses to E1E2 and an inverse response to increasing amounts of antigen was noted.

Conclusions

The vaccine was safe and generally well-tolerated at each of the 3 dosage levels and induced antibody and lymphoproliferative responses. A larger study to further evaluate safety and immunogenicity is warranted.     

CYP2E1 Ras I基因型对苯酚诱导的酶活性和DNA损伤作用的影响

[目的]研究3种CYP2E1 Ras I基因型对苯酚诱导永生化人淋巴细胞的CYP2E1酶活性及DNA损伤作用的影响。[方法]加入不同浓度的苯酚对CYP2E1 Ras I不同基因型的永生化人淋巴细胞进行24～72 h染毒,采用四甲基偶氮唑蓝法(Methyl Thiazolyl Tetrazolium,MTT)测定细胞毒性并确定苯酚染毒剂量;采用苯胺分光光度法测定CYP2E1酶活性;采用单细胞凝胶电泳(SCGE)法测定DNA损伤作用。[结果]0．05％苯酚24 h染毒对CYP2E1 Ras I野生、杂合及突变基因型细胞均产生生长抑制作用,苯酚对细胞24～72 h染毒的最大无作用浓度为0．01％。各基因型细胞经一定浓度苯酚诱导后酶活性升高(P<0．05),其中野生型细胞经0．005％和0．01％浓度的苯酚染毒可出现酶活性增高的效应,突变型和杂合型细胞经0．01％浓度染毒可出现酶活性增高的效应,且染毒72 h时,在0．01％苯酚染毒剂量下各基因型细胞的CYP2E1酶活力出现明显差异,其中野生基因型细胞的CYP2E1酶活力显著高于突变型、杂合型基因型细胞(P<0．05)。各基因型细胞经一定浓度苯酚染毒后可出现DNA损伤效应,与对照相比,细胞的拖尾率、尾DNA含量及尾长显著升高(P<0．05),且染毒48 h、72 h时,野生基因型细胞的DNA损伤效应与突变型、杂合型细胞相比更为明显(P<0．05)。苯酚诱导后细胞的DNA损伤与CYP2E1酶活性之间呈现明显正相关性。[结论]CYP2E1 Ras I不同基因型明显影响苯酚对人淋巴细胞CYP2E1酶的诱导活性和DNA的损伤程度,其中CYP2E1 Ras I野生基因型细胞的作用最为明显。     

Effects of a high fructose diet on lipogenic enzyme activities in some organs of rats fed ad libitum.

The effect of a high fructose diet on lipogenesis was studied in rats. Male and female rats were divided into three groups and were fed a high carbohydrate diet ad libitum for 4 days: group 1 was fed a high cornstarch diet, group 2 was fed a high fructose diet without starvation, and group 3 was fed a high fructose diet after 2 days of starvation. The activities of lipogenic enzymes, i.e., glucose-6-phosphate dehydrogenase and malic enzyme were assayed in liver, adipose tissue, and small intestine. The lipid content of liver was also determined. On day 4, the lipid content of group 1 was about 45 mg, that of group 2 was about 70 mg, and that of group 3 was about 115 mg (female) and 145 mg (male) per gram of wet weight. Groups 2 and 3 showed significantly higher activity of hepatic malic enzyme than group 1. The activity of intestinal malic enzyme was highest in group 1 and not significantly different between groups 2 and 3. The malic enzyme activity in adipose tissue of females of group 3 was higher than that in either sex of the other groups.     

Carrageenan as an adjuvant to enhance peptide-based vaccine potency

New innovative therapies are urgently required in order to combat the high mortality and morbidity associated with advanced cancers. Antigen-specific cancer immunotherapy using peptide-based vaccination has emerged as an attractive approach for the control of cancers due to its simplicity and easy preparation. However, such an approach requires the employment of suitable adjuvants. In the current study, we explored the employment of a sulfated polysaccharide compound from red algae, carrageenan (CGN) as an adjuvant for their ability to generate antigen-specific immune responses and antitumor effects in mice vaccinated with human papillomavirus type 16 (HPV-16) E7 peptide vaccine. We found that carrageenan can significantly enhance the E7-specific immune responses generated by E7 peptide vaccination via the TLR4 activation pathway. In addition, carrageenan could enhance the protective and therapeutic antitumor effects generated by E7 peptide vaccination against E7-expressing tumors. Furthermore, the observed enhancement was not restricted to E7 antigen but was also applicable to other antigenic systems. We also found that other structurally similar compounds to CGN, such as dextran, also generated similar immune enhancement. Thus, our data suggest that CGN and its structurally related compounds may serve as innovative adjuvants for enhancing peptide-based vaccine potency.     

Human brain: aldehyde dehydrogenase activity and isozyme distribution in different areas

Three human post-mortem brains were dissected into seventeen areas and assayed for aldehyde dehydrogenase (EC 1.2.1.3) activity employing two assay systems: one at 68 microM and another at 13.6 mM propionaldehyde. The levels of activity with 68 microM propionaldehyde were significantly higher in cerebellum and putamen. The same brain areas were also examined by isoelectric focusing. By this procedure two distinct bands of aldehyde dehydrogenase activity (the cytoplasmic E1 and mitochondrial E2) could be readily visualized in cerebellum and putamen while other brain areas contained mainly the mitochondrial E2 isozyme.     

Priority Preferences: “End of Life” Does Not Matter,But Total Life Does

There is increasing evidence that the social value of an incremental health gain depends on patient characteristics, such as their age and their prognosis. This article presents an analytical framework to illustrate how a disease splits our life expectancy into 1) past health (age), 2) prognosis untreated, 3) gain from treatment, and 4) incurable loss. A Norwegian population sample was asked to make pairwise choices and prioritize hypothetical patients who differed in terms of age (30, 50, and 70 years old), remaining lifetime without treatment (1, 3, and 10 years), and increase in remaining lifetime with treatment (1 month, 3 months, 1 year, and 3 years). Their preferences reveal strong support for the “fair innings” argument that total lifetime inequalities should be reduced. Differences in patients’ remaining lifetime without treatment did not matter, implying little support for the “end-of-life” argument that a short life expectancy makes patients entitled to preferential treatment.     

Time-course of changes of liver tryptophan pyrrolase (tryptophan oxygenase) and liver and kidney glucose-6-phosphatase in rats shifted from high- to zero-protein diets

Time-courses of changes in the activities of liver and kidney glucose-6-phosphatase [EC 3.1.3.9] and hepatic tryptophan pyrrolase [EC 1.13.1.12; TPO] in rats pre-fed high-protein diets for 5 days and then shifted to zero-protein diets were studied. Liver glucose-6-phosphatase activity decreased 1 day after the dietary shift but then increased and remained significantly higher than the 0 day value for the next 2 days. Changes in liver glycogen were found to be intimately and inversely related to liver glucose-6-phosphatase activity. Changes in kidney glucose-6-phosphatase activity paralleled the pattern of changes observed in liver activity. An initial decrease in TPO activity was followed by increased enzyme activity up to the 3rd day of the dietary shift. Later there was a rapid fall in tryptophan pyrrolase activity. Changes observed in these specific enzyme proteins differed from those observed in total tissue proteins. Alterations in the activities of these enzymes and changes in other parameters are compared with those observed earlier with the reverse type of dietary shift.     

Subcellular distribution of aldehyde dehydrogenase activities in human liver

The subcellular distributions of aldehyde dehydrogenase activities towards acetaldehyde have been determined in wedge-biopsy samples of human liver. A form with Km values of less than 1 microM and 285 microM towards acetaldehyde and NAD+ respectively was present in the mitochondrial fraction. This enzyme had no detectable activity towards N-tele-methylimidazole acetaldehyde, the aldehyde derived from the oxidation of N-tele-methylhistamine. The activity in the cytosol was more sensitive to inhibition by disulfiram and had Km values of 270 microM and 25 microM for acetaldehyde and NAD+, respectively. It was active towards N-tele-methylimidazole acetaldehyde with a Km value of 2.5 microM and a maximum velocity that was 40% of that determined with acetaldehyde. Both these cytosolic activities had alkaline pH optima.     

The pathogenetic significance of intestinal Candida colonization--a systematic review from an interdisciplinary and environmental medical point of view

The etiological significance of intestinal Candida colonization continues to be controversial. This is a systematic review to determine the pathogenetic significance of intestinal Candida colonization. The search was essentially performed from 1990 to 12/7/2000 in Medline and the Cochrane-Library. The data source was restricted to articles in English and German. Selection criteria covered the topics "Epidemiology", "Infectious Diseases", "Candida-Syndrome" and "Therapy" and were essentially confined to in-vivo examination of immunocompetent adults. Two reviewers extracted independently data using predefined criteria. In total, 96 citations that proved suitable for use in the systematic review were found. Depending on the localization in the gastrointestinal tract, the recovery technique employed, and transport times, Candida colonization is frequently detected in healthy, immunocompetent adults (prevalence: 4-88%). None of the studies available so far furnish any evidence that nutritional factors, food additives, pollutants, anti-ovulants, other types of medication or diabetes mellitus might be predisposing factors for intestinal Candida colonization. However, therapeutic studies point to the possibility of Candida playing a role in antibiotic-associated diarrhea. On the other hand, antibiotics seem to favor bacterial dysbiosis, and this, like the direct side effects of drugs, offers a more plausible explanation for diarrhea or gastrointestinal symptoms. The role of intestinal colonization by Candida in Candida-associated vulvovaginitis and IgE-mediated disorders remains contradictory. Nevertheless, neither epidemiological nor therapeutic studies provide evidence for the existence of the so-called "Candida-syndrome" or "Candida-hypersensitivity-syndrome". At present, there are no proven treatment indications for antifungal "bowel decontamination".     

Effects of cadmium on ribosomal protein synthesis in rat liver.

Cadmium administered to rats at a dosage level of 2 mg Cd/kg body weight per week for 2–3 weeks caused inhibition of protein synthesis in vitro by isolated ribosomes in an amino-acid-incorporating system prepared from liver. The rate of translation on treated ribosomes was lowered by 25% when normal pH 5 enzyme was used in the assay system, and by 35% when cell sap was used as an enzyme source. The rate of incorporation was further diminished when enzymes were prepared from Cd-poisoned animals. Significant quantities of cadmium were found to be present in purified ribosomes and enzyme preparations, indicating attachment of cadmium to isolated ribosomes and proteins.     

Development of an interferon-gamma ELISPOT assay to detect human T cell responses to HSV-2

Background

The need for an HSV-2 vaccine is great considering the increasing prevalence of HSV-2 despite the widespread use of antiviral drugs. Human clinical trials of HSV-2 vaccines that elicit neutralizing antibodies have proven to be only partially effective suggesting that induction of effective T cell responses to HSV-2 is also a critical component to an efficacious vaccine. A sensitive and specific assay to measure HSV-specific T cell responses is a necessary part of vaccine development and thus we undertook the development of an interferon-γ (IFN-γ) ELISPOT assay to measure T cell responses to HSV-2.

Methods

PBMC from HSV-seronegative (HSVneg) (n = 35), HSV-1-seropositive (HSV-1+/2-) (n = 20) and HSV-2-seropositive (HSV-2+) subjects (n = 26) were screened by IFN-γ ELISPOT for T cell responses using 34 peptide pools representing 16 HSV-2 proteins including mostly virion and immediate-early (IE) proteins.

Results

Overall, 85% of HSV-2+ subjects had a positive response to the HSV-2 peptide pools and on average, HSV-2+ subjects responded to 3 peptide pools (range 1-10). The most frequent responses were to gD-2, UL39, UL46, ICP0, UL49, gB-2, and ICP4. In contrast, only 2 of 35 (6%) HSVneg subjects had detectable T cell responses and in both cases, responses were of low magnitude relative to responses in HSV-2+ subjects and were directed at a single peptide pool. The response rate to the HSV-2 peptide pools in HSV-1+/2- subjects was 40% suggesting that the HSV-2 peptide pools contain a significant number of type-common T cell epitopes. The IFN-γ ELISPOT assay detected CD4 and CD8 T cells directed at HSV-2 peptides as confirmed by intracellular cytokine staining and flow cytometry.

Conclusion

We have developed a quantitative IFN-γ ELISPOT assay that detects both CD4 and CD8 T cells to HSV-2 peptides. This assay does not require large quantities of PBMC to generate dendritic cells for T cell stimulation, making it an ideal assay for monitoring the immunogenicity of candidate HSV-2 vaccines designed to elicit T cell responses to HSV-2 specific epitopes.     

Superoxide Dismutase (SOD) Enzyme Activity Assay in Fasciola spp. Parasites and Liver Tissue Extract

Background

The purpose of this comparative study was to detect superoxide dismutase (SOD) activities in Fasciola hepatica, F. gigantica parasites, infected and healthy liver tissues in order to determine of species effects and liver infection on SODs activity level.

Methods

Fasciola spp. parasites and sheep liver tissues (healthy and infected liver tissues), 10 samples for each, were collected, homogenized and investigated for protein measurement, protein detection and SOD enzyme activity assay. Protein concentration was measured by Bradford method and SODs band protein was detected on SDS-PAGE. SODs activity was determined by iodonitrotetrazolium chloride, INT, and xanthine substrates. Independent samples t-test was conducted for analysis of SODs activities difference.

Results

Protein concentration means were detected for F. hepatica 1.3 mg/ ml, F. gigantica 2.9 mg/ml, healthy liver tissue 5.5 mg/ml and infected liver tissue 1.6 mg/ml (with similar weight sample mass). Specific enzyme activities in the samples were obtained 0.58, 0.57, 0.51, 1.43 U/mg for F. hepatica, F. gigantica, healthy liver and infected liver respectively. Gel electrophoresis of Fasciola spp. and sheep liver tissue extracts revealed a band protein with MW of 60 kDa. The statistical analysis revealed significant difference between SOD activities of Fasciola species and also between SOD activity of liver tissues (P<.05).

Conclusion

Fasciola species and liver infection are effective causes on SOD enzyme activity level.     

3种戊型肝炎病毒抗原检测血清抗—HEV IgG的比例研究

目的：用3种抗原检测国家戊型肝炎参比血清和急性戊型肝炎病人血清抗－HEV IgG。方法：人工合成戊型肝炎病毒（HEV）ORF2和ORF3多肽抗原（BMU抗原）检测参比血清的灵敏度（90．0％），特异度（100．0％）和符合率（97．5％）均高于杆状病毒表达的HEV重组蛋白空粒子抗原（JP抗原）（分别为70．0％，93．3％和87．5％）及大肠杆菌表达的重组蛋白抗原（HKU抗原）（分别为70．0％，90．0％和85．0％），检测84例急性戊型肝炎病人血清抗－HEV IgG，用BMU抗在检测抗－HEV IgG的阳性率为1000％（84／84），高于JP抗原（83／84，98．8％）和HKU抗原（71．84，84．5％）。结果：不同HEV抗原检测国家参比血清和急性戊型肝炎病人血清抗－HEV IgG的灵敏度和特异性不同，其差异主要与编码该3种抗原的HEV基因片段不同有关，ORF3抗原在检测急性HE病人中具有重要意义。联合应用ORF2和ORF3抗原可提高抗－HEVIgG检出率，结论：抗－HEV IgG ELISA诊断试剂至少应包括ORF2和ORF3 2种抗原。     

Comparison of dihydrofolate reductase activities for folic acid in pigs and rats using in vivo and in vitro evaluation techniques

The activity of dihydrofolate reductase (DHFR) for folic acid (PteGlu) was evaluated in pigs by in vivo and in vitro experiments. The results were compared with those of rats. Since bile secretion of reduced folates reflects the activity of DHFR for PteGlu in the body, the bile secretion rates of reduced folates including tetrahydrofolate (H4PteGlu), 5-methyltetrahydrofolate, 5,10-methylenetetrahydrofolate, and 10-formyltetrahydrofolate were determined by using high-performance liquid chromatography with electrochemical detection, after the intravenous injection of PteGlu at 1 mg/kg body weight to pigs and rats. Although the PteGlu injection raised the total secretion rate of reduced folates. the total increased amount of reduced folates secreted into bile from 0 h to 2.5 h after PteGlu injection in pigs was about one-tenth of that in rats. The enzyme kinetics of DHFR for PteGlu was examined at the physiological condition (pH 7.4 and 3 7 degrees C). Affinity chromatography was applied to liver homogenates of pigs and rats to obtain DHFR. The final product of the enzyme reaction, H4PteGlu, was measured. The Km for pig enzyme was similar to that for rat enzyme, whereas the Vmax for the pig enzyme was less than 1/5 of that for the rat's. The comparison of the ratio of Vmax to Km between pig and rat enzymes suggests that PteGlu is a much less efficient substrate for pig liver DHFR. In short, these results from in vivo and in vitro experiments suggest that the role of DHFR for PteGlu in pigs is physiologically much less important than that in rats.