Effect of Cu++ ions on the activity of trypsin on natural substance

In vitro experiments were carried out in order to investigate the influence of Cu++-ions on the tryptic hydrolysis of casein and soybean protein. The admixture of 10(-3) to 10(-2) Mol Cu++/l to the reaction preparations results in the activation of trypsin in both substrates. The further increase of the Cu++-concentration results in a decrease of the trypsin activity and, with casein as substrate, in trypsin inhibition. The effects are similar with the synthetic substrate N alpha-benzoyl-L-arginine-p-nitroamilide (L-BAPA), however, trypsin is already activated after the admixture of approximately 5 x 10(-6) Mol Cu++/l. Since the admixture of Cu++-ions in experiments with pepsin in similar concentrations as with trypsin also results in an activation, the question is being discussed whether the improved protein digestibility and the higher weight increase of pigs which received 250 ppm copper can be traced back to these effects.     

金黄色葡萄球菌胞外分泌蛋白的核酸酶活性研究

为研究金黄色葡萄球菌胞外分泌蛋白的核酸酶活性,本研究复苏培养金黄色葡萄球菌后取培养上清液,采用透析得到金黄色葡萄球菌胞外分泌蛋白,结果显示获得的该蛋白浓度为48.5μg/mL。采用琼脂糖凝胶电泳法、琼脂扩散法和琼脂培养法检测金黄色葡萄球菌胞外分泌蛋白的核酸酶活性,利用琼脂糖凝胶电泳法探究温度、pH、金属离子对核酸酶活性的影响。结果显示,金黄色葡萄球菌胞外分泌蛋白表现出降解λDNA的核酸酶活性,且最适温度和pH值分别为50℃和9.0,在低温和酸性条件下核酸酶的活性较弱,但胞外核酸酶对70℃以上的耐受性较差。不同浓度的Ba^2+、Mg^2+和Zn^2+对胞外分泌蛋白的核酸酶活性无影响;低浓度(0.01 mmol/L^1 mmol/L)的Ca^2+、Ni^2+、Cu^2+和Mn^4+可以促进胞外核酸酶切割λDNA的活性;高浓度的Na^+、K^+和Fe^3+可以提高胞外核酸酶切割λDNA的活性;添加Co^2+(0.01 mmol/L^10 mmol/L)可以促进胞外分泌蛋白的核酸酶活性。本研究证实了金黄色葡萄球菌胞外分泌蛋白的核酸酶活性,为进一步研究胞外分泌蛋白在金黄色葡萄球菌和宿主互作中的确切作用奠定了基础。     

Study of the acetylcholinesterase activity of Ascaridia galli: kinetic properties and the effect of anthelmintics.

Acetylcholinesterase (EC 3.1.1.7) activity was demonstrated in whole worm homogenates of adult Ascaridia galli with acetylthiocholine as substrate. The pH optimum was not measurable because of an autohydrolysis of the substrate. The Michaelis constant (Km) was 4 mM with saturation by excess substrate. Optimum enzyme activity was noted at a protein concentration of 200 mg/ml assay medium and at a temperature of 37 degrees C. Arrhenius plot of temperature dependence of the enzyme activity showed an energy of activation (delta Ea) of 28.962 K joule/mole above, and 25.448 K joule/mole below, the transition temperature (37 degrees C). Complete inhibition by eserine (physostigmine), a specific and classical acetylcholinesterase inhibitor, established the identity of the enzyme. A marginally higher enzyme activity was observed in females than in males as well as in homogenates from worms of mixed sexes. The enzyme was markedly activated by divalent metal cations such as Fe2+, Mg2+, Cd2+, Cu2+, Zn2+ and Ca2+, while Co2+ and Mn2+ inhibited the activity. Piperazine adipate at a concentration of 10(-3) M caused 45.5% and albendazole, a benzimidazole anthelmintic, 37.5% inhibition in the enzyme activity, while levamisole and mebendazole proved to be practically ineffective, causing an inhibition of 12 and 9%, respectively.     

鸡毒支原体磷酸酶PrpC活性检测

HPr激酶/磷酸酶(PrkC/PrpC)系统在细菌和支原体中高度保守,不仅参与糖酵解酶类的磷酸化/去磷酸化,也与毒力、生物被膜等生命活动相关。克隆并突变获得编码鸡毒支原体磷酸酶PrpC的ptc1基因,经原核表达纯化后,利用底物PNPP体外检测其酶活性,并对影响该酶活性的pH、金属离子、温度等影响因子进行分析。结果表明,Ptc1蛋白具有磷酸酶活性,Mn2+为该酶辅因子,最适离子浓度为2mol/L,最适pH为8.5,最适温度为37℃。相同浓度的Li+、Na+、K+、Mg2+、Ca2+、Ba2+、Al 3+、Hg2+等金属离子均对表达产物具有不同程度的抑制活性。初步建立了PrpC功能检测体系,为进一步深入研究PrkC/PrpC调节系统奠定基础。     

用薯莨提取液对真丝织物染色增重的最佳工艺及金属离子后处理的改性效果

采用天然染料改善真丝性能有利于环保和人体健康。研究了以天然薯莨提取液为染料,应用汽蒸染色方法对真丝织物进行染色增重的最佳工艺,比较了分别用Fe3+、Cu2+、Cr6+3种金属离子进行后处理的改性效果。薯莨提取液对真丝增重的最佳工艺是:汽蒸温度110℃、湿度85%,汽蒸8次,汽蒸时间4 min,带液率180%、含固量6.28%。用Fe3+、Cu2+、Cr6+金属离子后处理的最佳质量浓度分别为12、10、10 g/L。Fe3+、Cr6+后处理的真丝织物其增重率随离子浓度的增加逐渐增大,而Cu2+后处理的真丝织物增重率在离子浓度上升到一定程度后有所降低。用Fe3+后处理的真丝织物颜色最深,呈红黑色;用Cu2+后处理的真丝织物颜色偏深,色相在红黄之间;用Cr6+后处理的真丝织物偏暗黄色。3种金属离子用于染色真丝织物的后处理,均在一定程度上提高了薯莨提取液染色增重真丝的色牢度和拒水性能,能明显提高真丝织物的紫外屏蔽性能,其中经Cr6+后处理的真丝织物拒水性能和紫外屏蔽性能最为显著。     

The effect of various pH values on in vitro peptic digestion of proteins in the presence of Cu2 ions]

Studies were carried out to investigate the effect of different pH values on the peptic digestion of soya protein in the presence and in the absence of Cu2+ ions. The studies were performed in vitro at a pH of 2.2 and 3.2, with 2.96 X 10(-5) mole of Cu2+ ions present in 11 of the reaction mixture. The reaction was carried out in a digestion apparatus permitting dialysis of the cleavage products. Different parameters were used as criteria of digestion, viz. the quantity of N contained in the reaction vessel (residue) and in the resulting dialysis products as determined by Kjehldahl microanalysis and automatic amino acid analysis, the proportions of digestion products found in the different molecular ranges after partition of Sephadex G 75 and the composition of amino acids in the cleavage products. From the distribution of the reaction products on the residue and dialysis products and on the different molecular ranges it was found that additions of Cu2+ ions at pH 2.2 produced a considerable inhibition of digestion. With a rise in pH to 3.2 peptic digestion decreased even without the addition of Cu2+. Supplementation of Cu2+ ions produced only a slight additional effect in the molecular range termed "exclusion limit". In the case of the amino acids tyrosine and phenylalanine it was found that an increase in pH changed the composition of peptides within the different molecular ranges. Additions of Cu2+ had no influence on the amino acid composition.     

大理弥渡热泉耐热脂肪酶产生菌的筛选及其酶活性研究

从云南大理市弥渡县石夹泉热泉的43℃底泥中筛选到1株高温脂肪酶的高产菌,进行显微形态及生理生化特征、16S rRNA基因序列分析,将其初步鉴定为不动杆菌属(Acinetobacter sp.)的一株菌,命名为Acinetobacter sp.Lip-43。对其生长条件及酶学性质进行了研究,结果表明:该菌株耐高温性较好,菌株在55℃仍能生长,菌株最适生长温度为37℃。所产脂肪酶最适酶活温度为45℃,最适反应pH为5.0。在37℃以下,能保持良好的稳定性,Zn^2+和Ca^2+对该酶有一定的抑制作用,Mn^2+、K^+、Mg^2+、Fe^2+、Cu^2+均对该酶活力起到促进作用,其中Mn2+的促进效果最为明显。     

产α-半乳糖苷酶菌株的筛选、鉴定及其酶学特性的研究

利用筛选培养基从不同豆制品作坊附近的土样中筛选出一株产α-半乳糖苷酶的菌株D-1,对其进行分子鉴定及所产的α-半乳糖苷酶进行酶学特性研究。研究表明,菌株D-1为Aspergillus niger,此菌株所产α-半乳糖苷酶的最适反应温度是55℃,在60℃以下热稳定性较好;最适反应pH值为5.0,在pH值3.0～5.5范围内稳定性较好,相对酶活>64.1%;Mg2+、Na+、Pb2+、K+、Mn2+、Co2+、Al3+对α-半乳糖苷酶均有不同程度的抑制作用,其中Cu2+和Fe3+的抑制作用较为明显,而Ca2+、EDTA(乙二胺四乙酸)、Zn2+对α-半乳糖苷酶有一定的促进作用。     

Effects of feeding ergovaline on lamb performance in a heat stress environment

Lambs exposed to a heat-stressed environment (33 degrees C, 50% relative humidity) were used in three experiments to determine whether ergovaline (EV) is the primary toxin involved in fescue toxicosis. The first study evaluated the effects of feeding diets containing increasing levels of endophyte-infected tall fescue seed (E+) and decreasing levels of endophyte-free tall fescue seed (E-). The second and third study evaluated the response to a diet that contained synthetic EV added to an E- diet and the response to a diet containing endophyte-infected ryegrass seed (R+) with an elevated concentration of EV. In Exp. 1, lambs were fed diets of: 1) 10% E- and 0% E+, 2) 5% E- and 5% E+, or 3) 0% E- and 10% E+. Increasing the percentage of E+ in the diet resulted in a linear decrease (P < 0.01) in feed intake (as-fed basis), skin temperature, thermocirculation index (TCI), and serum prolactin. Body weight gain also decreased (P < 0.06). Respiratory rate and core body temperature were not affected by the 5 or 10% E+ diets. In Exp. 2, lambs were fed diets that contained: 1) 10% E-, 2) 10% E- with synthetic EV added at a level equivalent to the 10% E+ diet, or 3) 10% E+. Feed intake (as-fed basis), body weight gain, and skin temperature did not differ for lambs fed the E- and EV diets. The EV diet elicited a decrease (P < 0.05) in TCI and prolactin compared with the E- diet. The TCI for lambs fed EV did not differ (P > 0.10) from the E+ lambs; however, serum prolactin was lower (P < 0.05) for lambs on the E+ diet than for those fed EV. Core body temperature was not affected (P > 0.10) by feeding EV or E+ fescue seed in Exp. 2. In Exp. 3, lambs were fed diets that contained: 1) 10% E-, 2) 3.24% R+ and 6.76% E-, which added an equivalent amount of EV to E+ diets but reduced concentrations of other ergot alkaloids, or 3) 10% E+. Lambs fed the E+ diet and maintained at 33 degrees C had lowered feed intake (as-fed basis), skin temperature, and TCI compared with lambs fed the E- or R+ diets (P < 0.05). Lambs fed the E+ diet had increased rectal temperatures and lowered serum prolactin compared with lambs on the R+ diet (P < 0.05). Lambs on the R+ diet had a greater rectal temperature and lower serum prolactin than lambs on the E- diet (P < 0.05). These results suggest that EV is a fescue toxin; however, other alkaloids might work synergistically with EV, causing the full expression of fescue toxicosis.     

母乳乳清蛋白抗氧化活性肽的研究

母乳是婴幼儿的最佳食物来源,而乳清蛋白是营养和活性物质的基础,其中生物活性肽对人体健康具有重要促进作用.为研究母乳乳清蛋白抗氧化活性肽,采用中性蛋白酶、碱性蛋白酶、木瓜蛋白酶和胰蛋白酶4种酶制备抗氧化活性多肽,通过单因素试验和响应面分析对乳清蛋白酶解工艺进行优化.结果表明:中性蛋白酶最适于母乳乳清蛋白抗氧化肽的制备,此时的最佳工艺参数为pH 7.21、反应温度50.03℃、酶与底物比(E/S)4 486.68 U/g、酶解时间5h;影响1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率的因素大小为:酶与底物比＞温度＞pH值.利用大孔树脂、葡聚糖凝胶过滤色谱G-25、G-15分析得出组分峰Ⅰ抗氧化活性最强,其DPPH自由基清除率达到了60.31％.     

Prevalence of the enteroaggregative Escherichia coli heat-stable enterotoxin 1 gene and its relationship with fimbrial and enterotoxin genes in E. coli isolated from diarrheic piglets.

A total of 720 Escherichia coli strains isolated from diarrheic piglets on 756 swine farms were screened for the presence of the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene by polymerase chain reaction (PCR). Escherichia coli strains that carried EAST1 genes were also tested by PCR for the presence of 4 fimbriae (F4, F5, F6, F41), 2 heat-stable enterotoxins (STa and STb), and 1 heat-labile enterotoxin (LT) gene. One hundred sixty-four (22.7%) of the 720 E. coli isolates carried genes for EAST1. Of these 164 isolates, 62 (37.8%) carried EAST1 genes only, 11 (6.7%) carried genes for at least 1 of the fimbrial adhesins, 51 (31.1%) carried genes for at least 1 of the enterotoxins, and 40 (23.8%) carried genes for at least 1 of the fimbrial adhesins and enterotoxins. Forty-six percent of strains that carried EAST1 genes carried STa genes, and 16% of strains that carried EAST1 genes carried F4. The isolation rate of enterotoxigenic E. coli strains carrying genes for EAST1 gene was 63%. The 6 major genotypes observed in this study (in decreasing order) were EAST1+, EAST1+STa+, EAST1+STa+STb+, EAST1+STa+F5+, EAST1+STa+F4+, and EAST1+STb+F4+. EAST1 is widely prevalent among diarrheagenic strains of E. coli and may represent an important virulence determinant in the pathogenesis of enteric colibacillosis of preweaned pigs.     

Leukocyte subsets and specific antibodies in pigs vaccinated with a classical swine fever subunit (E2) vaccine and the attenuated ORF virus strain D1701

Total white blood cell (WBC) counts and percentages of CD4a+, CD8a+, CD5a+, CD45RA+, CD45RC+, wCD21+ and SWC3a+ cells in the peripheral blood of pigs were analysed in this study. Blood samples were collected before and on days 4, 10, 21 and 28 after vaccination. Group 1 pigs were vaccinated with a subunit E2 vaccine (gp E2 32 microg/dose), and Group 2 received a subunit vaccine combined with an attenuated ORF virus strain D1701 10(6.45) TCID50/dose. Control pigs received a placebo. The total WBC count and percentage of particular cell types were within the normal range in vaccinated and control pigs. Although the mechanism of attenuated ORF virus activity is not clear, changes were observed in CD4a+, CD5a+, CD8a+, CD45RA+ and CD45RC+ cells in pigs that received the combination of a subunit vaccine and ORF virus. However, the percentage of wCD21+ and SWC3a+ did not differ significantly from that recorded in pigs given only the subunit vaccine. At days 4 and 10 the number of pigs positive to E2 antibodies was higher in the group that received the subunit vaccine and ORF virus than in pigs vaccinated with the subunit vaccine only. A higher percentage of memory cells (CD45RC+) as well as Th and Tc lymphocytes in pigs that received the ORF virus and the subunit vaccine could be ascribed to a nonspecific influence of the ORF virus on the development (through cognate interactions between T and B cells) and the duration (presumed according to the finding of the clonal expression of memory cells) of humoral immunity (assessed by a higher number of seropositive pigs in this group). This seems likely since the proportion of these cells was found to be lower in the pigs that received E2 vaccine only.     

Preparation,characterization, antimicrobial and cytotoxicity studies of copper/zincloaded montmorillonite

Background: A series of modified montmorillonites(Mt) including zinc-loaded Mt(Zn-Mt), copper-loaded Mt(Cu-Mt), copper/zinc-loaded Mt with different Cu/Zn ratio(Cu/Zn-Mt-1, Cu/Zn-Mt-2, Cu/Zn-Mt-3) were prepared by an ion-exchange reaction, and characterized using X-ray diffraction(XRD), fourier transformed infrared spectroscopy(FTIR) and transmission electron microscopy(TEM). The specific surface areas, antimicrobial activity and cytotoxicity of the modified Mt were investigated.Results: In the modified Mt, hydrated Cu ions and Zn ions were exchanged in the interlayer space of Mt and the particles were irregular shapes. The results showed that Cu/Zn-Mt enhanced antibacterial and antifungal activity compared with Zn-Mt and Cu-Mt possibly due to the synergistic effect between Cu and Zn. Among the Cu/Zn-Mt with different Cu/Zn raitos, Cu/Zn-Mt with a Cu/Zn ratio of 0.98 or 0.51 showed higher antimicrobial activity against gram-negative bacteria(Escherichia coli), gram-positive bacteria(Staphylococcus aureus), fungi(Candida albicans).Moreover, the antimicrobial activity of Cu/Zn-Mt was correlated with its specific surface area. Cytotoxicity studies on IPEC-J2 cell showed a slight cytotoxicity of Cu/Zn-Mt.Conclusions: The current data provide clear evidence that in terms of its antimicrobial activity and relatively low toxicity, the Cu/Zn-Mt holds great promise for applications in animal husbandry.     

牛血Cu/Zn-SOD提取条件的研究

本研究以牛血为试验材料,研究了Cu²+浓度、Zn²+浓度、热变性温度和热变性时间4种单因素分别对牛血中Cu/Zn-SOD活性的影响。以4种单因素为基础设计了4因素5水平正交试验,通过邻苯三酚法测定了酶活性,考马斯亮蓝法测定了蛋白含量,聚丙烯酰胺凝胶电泳测定了蛋白纯度,确定了牛血Cu/Zn-SOD的最佳提取条件。结果表明：当Cu²+、Zn²+分别为6和12 mmol/L条件下,90 ℃热变性35 min,可得到较高活性和比活力的Cu/Zn-SOD。本研究意在为更简便、经济的牛血中Cu/Zn-SOD提纯方法提供参考。     

H2O2与Fe2+、Cu2+、Zn2+协同作用对桑自由基伤害和保护酶活性的影响

研究了H2O2与Fe2+等金属离子产生的自由基胁迫对桑树生理特性的影响,旨在为桑树的抗逆栽培提供理论参考。以桑树叶片为材料,研究H2O2与Fe2+、Cu2+、Zn2+协同作用对桑自由基伤害和保护酶活性的影响。结果表明:经H2O2-Fe2+、H2O2-Cu2+和H2O2-Zn2+3种体系溶液处理的桑.OH含量分别提高34.38%、8.14%和5.43%;O2.-含量分别降低78.77%、54.75%和63.84%;1,1-二苯基苦基苯肼(DPPH)清除率分别降低44.60%、57.34%和54.64%;超氧化物歧化酶(SOD)活性分别提高44.45%、36.02%和28.28%;多酚氧化酶(PPO)活性分别降低68.18%、86.58%和54.78%;过氧化氢酶(CAT)活性分别降低97.46%、96.57%和68.02%;过氧化物酶(POD)活性分别降低22.22%、提高7.42倍和66.67%。H2O2与Fe2+等的协同作用破坏了桑细胞内自由基动态平衡,导致自由基含量提高,保护酶活性受到显著影响。     

桑椹红色素稳定性的研究

研究了光和热等物理因素、常用食品添加剂、金属离子、氧化剂及还原剂对桑椹红色素稳定性的影响。结果表明 :pH值对桑椹色素的影响显著 ,在酸性条件下色素稳定 ;长时间高温和光照对色素有明显的破坏作用 ;金属离子Na+ 、Ca2 + 、Cu2 + 、Fe2 + 、Mg2 + 、Zn2 + 和Mn2 + 对桑椹色素色泽有一定的增色效果 ,但Fe3 + 则有明显的不良影响 ;食品中常用的葡萄糖、蔗糖、苯甲酸钠和山梨酸钾对桑椹色素无明显的不良影响 ;VC对桑椹色素有双重作用 ,而H2 O2 和Na2 SO3 对色素有严重的破坏作用。     

The effect of experimental infectious mastitis on leukocyte subpopulations and cytokine production in non-lactating ewes.

The interactions between leukocytes and cytokines during the acute response to intramammary infections in the dry mammary gland of sheep were studied. Dry ewes were experimentally infected in one udder half with either Staphylococcus aureus or Escherichia coli, or infused with saline as control. Udder secretion samples, blood samples and udder tissue samples were collected before and 4, 8 and 24 h after infections/infusions. Total and differential leukocyte counts were calculated in both blood and mammary secretions, and flow cytometry was used to detect the presence of CD4+, CD8+, WC1+, IL-2R+, CD18+ or L-selectin + lymphocytes, CD18+ or L-selectin + neutrophils, and CD14+ leukocytes. Moreover, the concentrations of interleukin-1 beta (IL-1 beta), interleukin-8 (IL-8) and granulocyte-macrophage colony stimulating factor (GM-CSF) in udder secretions were measured using ELISA, and RT-PCR was used to detect the presence of corresponding cytokine mRNA in udder tissue biopsies. The results suggest an association between the concentrations of IL-1 beta, IL-8 and the intensity of neutrophil infiltration of the infected gland. Immunologically relevant changes in proportions of lymphocyte subpopulations might also occur in the acute phase of the inflammatory reaction of the udder. Greater cellular and cytokine responses to E. coli infection may have contributed to the milder clinical picture and more rapid resolution of infection than that seen for S. aureus. Enhancing the production of pro-inflammatory cytokines may improve defence against bacterial mastitis.     

Effects of Pasteurella haemolytica leukotoxin on cultured bovine lymphoma cells

Leukotoxin activity from culture supernatants of Pasteurella haemolytica serotype 1 in logarithmic growth phase caused rapid (less than 5 min) release of intracellular K+, uptake of extracellular Ca2+, and swelling of cultured bovine lymphoma cells (BL3 cells). Release of 51CrO4(2-) and lactate dehydrogenase (LDH) from BL3 cells began after 15 minutes of incubation with leukotoxin at 37 C and was completed between 60 and 120 minutes of incubation. In addition, leukotoxin exposure of BL3 cells resulted in cell aggregation and adherence to glass surfaces. Scanning electron microscopy indicated that after 10 minutes of leukotoxin exposure, BL3 cells increased in size, and large membrane defects developed between 20 and 60 minutes of exposure. The rate of release of LDH from leukotoxin-exposed BL3 cells was proportional to the amount of leukotoxin added. At high cell concentrations, the activity of LDH released at completion was directly proportional to the amount of leukotoxin added. Leukotoxin-induced release of LDH required a divalent cation, whereas K+ release and cell swelling did not. The addition of Ca2+, Mn2+, and Ba2+ resulted in increased leukotoxin-induced release of LDH. Divalent cation concentrations of 0.5 to 2.5 mM resulted in 50% of maximal stimulation. Ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid blocked increased release of LDH caused by Ca2+ addition, but had no effect on K+ release or cell swelling. Leukotoxin action on BL3 cells (K+ release, cell swelling, Ca2+ uptake, and release of LDH) was prevented by incubation at 4 C.     

Effect of calf thymus extract and zinc supplementation on the cellular response of mice exposed to restraint stress

The studies were carried out on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. Prior to stress exposure, the mice were treated with calf thymus extract (TFX - Jelfa) i.p. at a dose of 10 mg/kg, ten times at 24 h intervals. TFX was used per se or with zinc ions interaction, by adding zinc ions (as sulfate salt) to drinking water at a dose of 72 microg/mouse per day. The results obtained show that restraint stress dramatically decreased the total number of thymocytes and splenocytes which is also accompanied by decreasing weight ratio of the thymus and spleen. The decreasing number of thymic and spleen cells corresponded to a diminishing percentage of immature, double-positive CD4+CD8+ thymocytes, mature single-positive CD4+ thymic cells and CD4+, CD8+ and CD19+ splenocytes. Changes in the number of thymic cells affect their activity, which is expressed as a decreased proliferative response of thymocytes stimulated in vitro with concanavalin A (Con A) and phytohaemagglutinin (PHA). Besides, exposure to the restraint stress decreased interleukin-1 (IL-1) production by murine intraperitoneal macrophages stimulated in vitro with lipopolisacharide (LPS) from E. coli. Previous treatment with TFX counteracted restraint stress-induced immunosuppression, which is expressed as partial normalisation of the total number of thymic and spleen cells, accelerated regeneration of these two lymphatic organs, shortned suppressive action of restraint stress on the percentage of immature CD4+CD8+ thymocytes and CD4+ splenocytes and in total normalisation of the CD4+ thymocytes and CD8+ splenocytes. TFX administered prior to restraint stress not only counteracted the suppresive effects of stress on the proliferative activity of thymic cells stimulated in vitro with Con A and PHA, but also augmented the proliferative response of these cells to two mitogens. The immunorestorative effect of TFX was augmented by zinc supplementation.     

Prevalence of genotypes for fimbriae and enterotoxins and of O serogroups in Escherichia coli isolated from diarrheic piglets in Korea.

Polymerase chain reaction for 4 fimbriae (F4, F5, F6, F41), 2 heat-stable enterotoxins (STa, STb), and 1 heat-labile enterotoxin (LT) were performed on 400 Escherichia coli isolates to determine their genotype prevalence among enterotoxigenic E. coli isolates from preweaned pigs with diarrhea in the Republic of Korea. A total of 200 of the 400 E. coli isolates were also selected for characterization of the O serogroup. Of these 200 isolates, serogroup could be determined in 139 (69.5%) but not in 61 isolates (30.5%). Isolates of serogroup O101 were the most common, followed in descending order by 08, 020, 0162, 0141, and 0149. Ninety-seven (24.3%) of the 400 E. coli isolates carried genes for at least 1 of the entertoxins or fimbrial adhesins. Of these 97 isolates, 27 carried genes for at least 1 of the fimbrial adhesins and entertoxins. Sixty-six percent of the isolates that carried fimbrial adhesin genes carried genes for at least 1 of the enterotoxins, and 71% of the isolates that carried enterotoxin genes carried genes for at least 1 of the fimbrial adhesins. Genes for the F6 fimbriae were detected in 6% of the E. coli isolates, and F4+, F41+, and F5+ genes were detected in 4.3%, 3.3%, and 2% of the isolates, respectively. Genes for STa, STb, and LT were detected in 10%, 8.5%, and 4.3% of the isolates, respectively. The 6 major genotypes observed in this study (in decreasing order) were F6+, STb+, F41+, STa+STb+, F6+STa+, and STa+.