Plasmodium berghei: Detection in organs of infected mice by means of immuno-fluorescence

An immunofluorescent study of the malarial antigen in the tissues of mice infected with Plasmodium berghei (berghei strain) was conducted. In the first week of infection, the malarial antigen appears in corpuscular forms in the erythrocytes located in the vessels of the spleen, liver and kidney. From the second week onward, when antibodies to malaria begin to be detected, a new form of the malarial antigen, which appears as coarse granules, is detected in the fixed RE cells of the liver, spleen and in the glomerular endothelial and mesangial cells. There is a progressive decrease in the amount of the corpuscular form of the malarial antigen with a concomitant increase in the granular form. In the third week, most of the malarial antigen in the tissues is granular and the corpuscular form is rarely seen.     

Selection of a strain of albino mice refractory to Plasmodium berghei infection

Some features of the natural history of malaria in holoendemic areas can be explained by the presence of acquired immunity. There is also evidence that transmission of humoral antibodies in utero from the immune mother plays some part in the transient protection of the offspring. Little is known about the importance of a genetic factor.     

污灌玉米有机提取物致小鼠肝肾氧化损伤作用

目的 研究某污灌区玉米中有机污染物对小鼠肝肾组织的氧化损伤作用。方法 采用超声振荡法提取某污灌区农田生产的玉米中的有机污染物,对小鼠进行灌胃染毒2周;测定肝、肾组织的总超氧化物歧化酶(T-SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)。结果 污灌区低、高剂量组肝组织的T-SOD活性分别为(32.44±7.93),(30.92±9.29)U/(mg.prot);肾组织的GSH-PX活性分别为(67.28±27.21),(66.52±15.19)U/(mg.prot),与对照组比较均明显降低(P<0.05或P<0.01)。结论 该污灌区玉米有机提取物中含有致小鼠肝肾组织氧化损伤的有机污染物;对照区玉米中的有机污染物很可能来源于被污染的大气。     

Modification by a latent contaminant of glomerular pathology in mice infected with Plasmodium berghei

This study was designed to determine, by means of electron microscopy, the effect of latent contaminants—which are associated with the syringe passage of the parasite—on the findings in the glomeruli of P. berghei-infected mice. A rapid alteration of the glomerular basement membrane was observed in mice infected with the syringe-transmitted N strain, but not in those infected with the cyclically passaged Nig strain. Glomerular changes were also seen in mice inoculated with nonparasitized blood from normal mice, obtained after 16 passages by syringe. It appears that these changes were provoked by a latent contaminant that had proliferated after passages of the parasite through mice, and that they constitute a secondary immune reaction.     

Loss of infectivity for Swiss mice of a mefloquine-resistant strain of Plasmodium berghei

A strain of Plasmodium berghei made resistant to a 244 mg/kg daily dose of mefloquine by interrupted subcurative therapy in successive passages in weanling rats, was maintained for more than six months under drug pressure and was cryopreserved. Experiments with this strain have shown its loss of virulence for intact mice. In splenectomized Swiss mice infection with this resistant strain is transient. The mefloquine resistance of this line was unstable and the strain became sensitive to mefloquine after 10 serial drug-free passages but did not recover its infectivity to mice.     

Acquired immunity to Plasmodium berghei yoelii in mice

Acquired immunity to malaria was investigated in mice which had recovered from a primary infection with P. b. yoelii. It was found that antibody synthesis and protection persisted at least 17 months, although both decreased somewhat during this interval. Strong cross-protection was exhibited against a virulent isolate of the parent strain but not against the type species, P. b. berghei. It was not possible to detect persisting antigen or persisting infectious organisms in immune mice; both blood-induced and sporozoite-induced infections were followed from this standpoint.     

金属硫蛋白对铬染毒小鼠肝脏氧化损伤的修复作用

目的：探讨金属硫蛋白（MT）对六价铬（Cr6^＋）染毒小鼠肝脏氧化损伤的修复作用。方法：60只清洁级昆明（KM）种小鼠雌雄各半,随机分为5组：对照组,铬（Cr6^＋）染毒组（50mg／kg）,低、中、高（5．0、10．0、20．0mg／kg）剂量MT保护组。对照组灌胃生理盐水,铬染毒组按50nag／（kg·bw）灌胃重铬酸钾溶液;MT保护组在给予铬染毒的同时继续分别按5．0、10．0、20．0mg／（kg·bw）剂量灌胃MT。各组灌胃时间均为15d,每日1次;灌胃体积均为0．1ml／（10g·bw）。实验结束麻醉处死动物采血,取肝脏计算其脏器系数;全自动生化分析仪检测肝功能AST、ALT、GGT含量;试剂盒检测肝组织SOD活性和MDA含量。结果：与对照组比较,铬染毒小鼠体重降低、肝脏器系数增高、血清AST、ALT、GGT增高、SOD活力下降、MDA含量增高（P〈0．05）。经MT保护后与铬染毒组比较小鼠体重有所回升、肝脏脏器系数下降、血清AST、ALT、GGT降低、SoD活力升高、MDA含量下降,其恢复程度与MT呈剂量－效应关系（P〈0．05）。结论：铬（Cr6^＋）对小鼠肝脏有损伤作用,MT对肝脏有保护作用,其机制与抗氧化作用有关。     

Suppression of the chloroquine resistance of Plasmodium berghei by treatment of infected mice with a microsomal monooxygenase inhibitor

Administration of a combination of chloroquine and the copper-lysine complex, copper(lysine)₂, an inhibitor of microsomal monooxygenases, considerably decreased the parasitaemia level of mice infected with a chloroquine-resistant strain of Plasmodium berghei. When given separately, chloroquine and the complex had no antimalarial effect. Use of a combination of monooxygenase inhibitors and chloroquine therefore appears to be a promising addendum to the chemotherapy of malaria caused by chloroquine-resistant parasites.     

alpha-Difluoromethylornithine induces protective immunity in mice inoculated with Plasmodium berghei sporozoites

Mice inoculated weekly with Plasmodium berghei sporozoites while under treatment with alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, developed protective immunity against subsequent challenge with this parasite. The percentage of mice protected was similar whether DFMO alone (55%) or DFMO + chloroquine (65%) was used. With chloroquine alone, only 12% of mice were protected. This protection was long-lasting (at least six months). The immunity protected against sporozoites but not against erythrocytic form inoculation. It is suggested that this protection is induced by antigens released from exoerythrocytic schizonts whose further development is inhibited by DFMO.     

Antisporozoite antibodies in mice immunized with irradiation-attenuated Plasmodium berghei sporozoites.

Sera from NMRI/NIH mice were tested for the presence of IgM and IgG anti-sporozoite antibodies using the indirect fluorescent antibody test (IFAT). Both IgM and IgG antibody titres were related to the number of immunizations with irradition-attenuated Plasmodium berghei sporozoites, and protection from challenge with subsequent non-attenuated sporozoites correlated with the pre-challenge antibody titre. Sera taken five days following challenge showed marked reductions in antibody titres, except for the group receiving the maximum (four) immunizations. Groups immunized with frozen sporozoites or mosquito tissue antigen developed neither antibodies to sporozoites nor protective immunity; nor did animals infected with parasitized blood. However, sera from mice immunized four times with attenuated sporozoites demonstrated IFA titres to blood-stage antigens. The results show that both IgM and IgG antisporozoite antibodies could be detected in mice immunized with attenuated-sporozoites by IFAT, and that the antibody titres correlated with protective immunity. Cross reaction with blood-stage antigens occurred, but the test should still prove useful.