Toxoplasma encephalitis of immunocompetent and nude mice: immunohistochemical characterisation of Toxoplasma antigen, infiltrates and major histocompatibility complex gene products

The experimental infection of immunocompetent and immunodeficient athymic mice with an avirulent encephalitogenic Toxoplasma strain (DX strain) was employed to study the ensuing encephalitic process by use of histological and immunocytochemical methods. In the acute phase of the infection Toxoplasma cysts and tachyzoites were accompanied by an infiltrate composed of macrophages, CD4+ and CD8+ T cells. In the chronic stage a granulomatous encephalitis developed. In contrast to immunocompetent NMRI mice, athymic nude NMRI mice died 3 weeks post-infection because of a generalized toxoplasmosis with predominant involvement of the brain. A salient feature of murine Toxoplasma encephalitis was up-regulation of class I and II major histocompatibility complex (MHC) gene products. Class I antigen was widely expressed on microglial cells and astrocytes. Class II antigen was only expressed on microglial cells despite a considerable astrogliosis. Our results indicate a differential expression of MHC-determined antigens on brain cells in acute and chronic murine Toxoplasma encephalitis.     

Contributions of ovarian failure and aging to blood pressure in normotensive perimenopausal women: a mixed longitudinal study

Epidemiologic studies have shown that blood pressure increases more rapidly in middle-aged women than in middle-aged men. Whether or not ovarian failure contributes to this rapid rise is still not clear. In a follow-up study begun in 1979 and to continue for 10 years, the blood pressure of 193 healthy normotensive perimenopausal women, who lived in the mixed rural/industrial community of Ede, the Netherlands and who were initially aged between 49 and 56 years, was measured annually. During the course of the study, the onset of menopause of each participant could be established. Because of the mixed longitudinal design of the study, it was possible to evaluate the effects of both chronologic aging and time pre- or postmenopause on blood pressure. After the first seven years of follow-up, it was demonstrated that blood pressure did not increase in 168 women whose body weight was relatively stable. After multivariate analyses, systolic as well as diastolic pressure showed a significant negative relation (slope, 1.34 mmHg per year and 0.63 mmHg per year, respectively) with the years since menopause. On the other hand, the observed positive relation (slope, 0.81 mmHg per year) of systolic pressure with chronologic aging was not significant. No consistent association was found between diastolic pressure and chronologic aging. It is concluded that menopause cannot be regarded as a cause of hypertension; on the contrary, ovarian failure appears to have a protective effect on the increase in blood pressure as a result of chronologic aging. on the increase in blood pressure as a result of chronologic aging.     

Cellular distribution of the iron-binding protein lactotransferrin in the mesencephalon of Parkinson’s disease cases

Changes in the distribution of the iron-binding protein lactotransferrin have recently been described in the central nervous system during a variety of neurodegenerative disorders. To investigate whether lactotransferrin is associated with the neuropathological changes that characterize Parkinson’s disease, we analyzed the distribution of this protein in the mesencephalon of neurologically normal individuals and patients affected with Parkinson’s disease using quantitative immunohistochemical methods. High levels of lactotransferrin were observed in a large population of neurons in the substantia nigra of control cases. Lactotransferrin-positive neurons were severely affected by the neurodegenerative process that occurs in Parkinson’s disease as indicated by a severe decrease in the number of immunolabeled neurons in all of these cases. Quantitative analysis also demonstrated higher immunolabeling levels of lactotransferrin in the surviving neurons in the substantia nigra and ventral tegmental area of Parkinson’s disease cases compared to control cases. These results suggest that lactotransferrin may participate actively in the mechanism of neuronal degeneration in Parkinson’s disease. Received: 16 October 1995 / Revised, accepted: 1 December 1995     

Fungal infections in cancer patients: An international autopsy survey

In an attempt to estimate the frequency of fungal infections among cancer patients, a survey of autopsy examinations was conducted in multiple institutions in Europe, Japan and Canada. Fungal infections were identified most often in leukemic patients and transplant recipients (25 % each). Fifty-eight percent of fungal infections were caused byCandida spp. and 30 % byAspergillus spp. There was considerable variability in the frequency of fungal infections in different countries. Nevertheless, this study clearly demonstrates that fungal infections represent a common complication in cancer patients, especially in patients with leukemia.     

Therapeutic activities of antibiotics in listeriosis

Not only viruses but also certain bacteria, fungi as well as protozoa are able to reside and multiply within host cells; some of these microorganisms are facultative, others obligate intracellular hosts. They differ from each other in their mode of entry and in their strategies to survive intracellularly. Some remain in the phagocytic vacuole where they either block the fusion of lysosomes or resist the attack of the acidic milieu as well as the enzymatic digestion and multiply. Others escape from the vacuole to the cytoplasm where they travel around. This implies that chemotherapy has to respect these various intracellular life cycles. Therefore an antibiotic treatment can only be effective when the drug arrives in an active form at the special site of microbial residence.Nicht nur Viren, sondern auch manche Bakterien, Pilze und Protozoen sind in der Lage, sich innerhalb von Wirtszellen zu vermehren; einige davon sind fakultativ, andere obligat intrazelluläre Erreger. Schon in der Art und Weise, wie sie in die Wirtszelle eindringen, unterscheiden sich die verschiedenen Erreger, aber erst recht in der Art, wie sie mit den intrazellulären Verhältnissen zurechtkommen. Manche bleiben nach der Phagozytose in der Vakuole, wobei einige die Fusion der Lysosomen hemmen, während andere trotz Fusion in dem sauren Milieu überleben. Andere wiederum entweichen ins Cytoplasma und vermehren sich dort. Für eine erfolgreiche Antibiotikatherapie bedeutet dies, daß der antimikrobielle Wirkstoff in aktiver Form an den jeweiligen, speziellen Ort der Residenz des Erregers gelangen muß.     

荧光原位杂交技术分析人结肠菌群方法研究

建立荧光原位杂交技术分析人体内结肠菌群的方法。取受试者新鲜粪便 ,选用 5种特异性的 16SrRNA寡核苷酸探针 ,检测粪便样本收集后的保存时间、温度 ,离心条件及样本固定液存放时间对杂交计数结果的影响。结果建立最佳实验条件为 :粪便样本收集后应尽快在 4℃下保存 ,放置时间不要超过 12小时即作处理 ;样本的适宜离心条件为 70 0g 2分钟 ;样本用多聚甲醛固定后在 - 80℃下存放时间不要超过 5个月。该方法具有较好的稳定性 ,可以有效地检出个体之间结肠菌群的差异。