β-果糖基转移酶的性质研究

目的研究低聚果糖产生菌黑曲霉 (Aspergillusniger)SIPI 6 0 2来源的 β 果糖基转移酶 (β FT)的性质。 方法经典的酶学研究方法。结果 β FT催化蔗糖转化成蔗果三糖的Km和Vmax分别为 2 6 8.37g L和 2 .37g (min·L) ;将蔗果三糖转化成蔗果四糖的Km和Vmax分别为 173.0 8g L和 0 .10g (min·L)。葡萄糖是 β FT的竞争性抑制剂 ,其Ki=2 4 5 .2 3g L。β FT反应的最适pH为 4 .5～ 6 .0 ,最适温度为 5 5℃。β FT在中性条件、5 0℃以下稳定性良好。β FT转化蔗糖生成低聚果糖的反应进程实验表明 ,高浓度的底物有利于提高反应速度和转化率 ,并且产物中果糖浓度较低浓度底物中低。结论黑曲霉SIPI 6 0 2来源的 β FT适合用于工业化生产低聚果糖     

The soil fungusChaetomium in the human paranasal sinuses

Chaetomium is a soil fungus of which more than 180 species are now known. Most species cause degradation of cellulose-rich substrates, such as components in soil, straw or wood. Growth ofChaetomium globosum is often stimulated in the presence ofAspergillus fumigatus, which excretes such compounds as sugar phosphates and phospho-glyceric acid. A 73-year-old woman, with longstanding pain and secretion from her left maxillary sinus, was admitted to hospital where an infundibulectomy was performed. Histological examination showed necrotic material with hyphae ofA. fumigatus and perithecia ofChaetomium sp. The latter fungus is rarely pathogenic to man.     

Zur Bedeutung von sekretorischen und stukturassoziierten Proteasen von Aspergillus fumigatus für die Pathogenese der invasiven Aspergillose

Zusammenfassung. Ein Charakteristikum der invasiven Aspergillose ist, daß Aspergillus fumigatus in der Lage ist, proteinreiche Gewebsschichten des Wirtes zu penetrieren. Verantwortlich hierfür könnten sekretorische Proteasen des Pilzes sein, die fibrilläre Proteine wie Kollagen oder Elastin aufweichen und so der Hyphe das Eindringen ermöglichen. Allerdings sprechen Infektionsversuche mit Gendeletions-Mutanten von allen bekannten sekretorischen Aspergillus-Proteasen gegen eine entscheidende Beteiligung dieser Enzyme an der Pathogenese der invasiven Aspergillose. Ebenso deuten mikroskopische Untersuchungen an Gefäßwand-pene-trierenden Aspergillen nicht auf eine stärkere Auflösung des Bindegewebes, so daß auch eine rein mechanische Verdrängung der Struktur-Proteine durch das Wachstum der Hyphe möglich wäre. Weiter vorstellbar ist auch eine streng lokalisierte Proteolyse an dén Wachstumszonen der Hyphen durch Zellwand-assoziierte Proteasen. Kandidaten für einen solchen Mechanismus sind Aspartat- und Serinproteasen, deren Aktivitäten in der Zellwandfraktion von A. fumigatus gefunden wurden. Summary. In the course of invasive aspergillosis, Aspergillus fumigatus is capable of penetrating any tissue of the host. Secretory proteinases of the fungus might facilitate the hyphae to grow through fibrillar proteins like elastin and collagen. However, using systemic infection models, no significantly reduced virulence could be shown with fungal mutants deficient for all known secretory proteinases. Thus, secretory proteinases might be of minor relevance for the pathogenesis of invasive aspergillosis. In addition, microscopic examination of aspergilli penetrating vessel walls did not reveal obvious lysis of wall proteins, thus emphasizing a mechanical disruption of fibrillar proteins by the growing hyphae. However, a strictly localized proteolysis at the tips of growing hyphae caused by wall associated proteinases might be involved. Candidates for such a mechanism art the activities of aspartic and serine proteinases which we have discovered in the cell wall fraction of A. fumigatus.     

免疫组织化学法在鼻窦真菌球诊断中的价值

目的　研究鼻窦真菌球的主要致病菌种 ,探索组织切片中快速鉴定主要条件致病真菌的组织病理学方法。方法　 2 5例鼻窦真菌球患者接受鼻窦病变清除术 ,对其组织病理标本分别进行了碘酸雪夫染色 (paraaminosalicylic ,PAS)和免疫组织化学染色 ,并比较两种方法的敏感性。 结果鼻窦真菌球以上颌窦发病率最高 ,其次是蝶窦。致病真菌检测 :曲霉菌感染 2 3例 (92 % ) ,白色念珠菌感染2例 (8% )。鼠抗曲霉单克隆抗体、兔抗白色念珠菌多克隆抗体可以分别鉴定组织中的曲霉菌和白色念珠菌。免疫组化和PAS染色的敏感性差异无显著性 (χ2 =0 2 72 ,P >0 0 5 )。结论鼻窦真菌球感染以曲霉菌属多见 ,免疫组化技术具有抗原特异性强、诊断快速的特点 ,为确定鼻窦组织的真菌感染以及鉴定真菌菌属提供了新的可靠方法     

False-positive Aspergillus galactomannan immunoassays associated with intravenous human immunoglobulin administration

ObjectivesEvidence of false-positive galactomannan enzyme immunoassay (GM-EIA) results associated with intravenous immunoglobulin (IVIG) administration is scarce. Here, we aimed to determine the false-positive rate of GM-EIA after IVIG administration and to identify the related factors.MethodsStandard GM-EIA was performed using diluted and pure human IVIG samples with and without heat treatment. We also included adult patients who had at least one GM-EIA result within 1 week of IVIG administration for analysis. Those who had prior invasive aspergillosis within 1 year before IVIG therapy were excluded. The clinical characteristics and galactomannan index (GMI) kinetics between patients with false-positive and true-positive GMI were compared.ResultsAll diluted and pure IVIG samples tested positive for GM. Heat treatment resulted in the considerable elevation of GMI. Of 48 patients with positive GM-EIA results within 1 week of IVIG administration, 22 (45.8%) were considered to have false-positive antigenaemia (false-positive group, FPG). After the completion of IVIG administration, a decline in GMI was observed in all FPG patients but in only 18 out of 26 patients (69.2%) with true-positive results (true-positive group, TPG). By 7, 14, and 18 days of IVIG administration, GMI reverted to negative values in 7/15 (46.7%), 18/20 (90%) and 22/22 (100%) FPG patients, respectively, and 6/24 (25%), 14/24 (58.3%), and 16/26 (61.5%) of TPG patients, respectively. The TPG was more likely to have two or more consecutively positive GMIs after IVIG administration than the FPG (adjusted odds ratio, 9.01; 95% confidence interval, 1.99–40.9).ConclusionsIVIG treatment may produce false-positive GM-EIA results. A positive GMI among patients receiving human IVIG should be interpreted with caution.     

Pacemaker infection due to Aspergillus: report of two cases and literature review

BACKGROUND: Aspergillus infections of pacing systems are extremely uncommon, and most cases reported are characterized by an aggressive behavior that may lead to death of the patient. HYPOTHESIS: The study was undertaken to assess the incidence of pacemaker infection due to Aspergillus in a defined population. METHODS: A retrospective review of the case histories of all patients who underwent pacemaker implantation in the reference center for a defined population over a 13-year period was undertaken. A literature review of pacemaker infections due to Aspergillus was conducted. RESULTS: Of the 1,321 patients who required pacemaker implantation at Hospital Xeral-Calde in the Lugo region of northwestern Spain, 38 suffered a pacemaker infection. A pacemaker pocket infection due to Aspergillus fumigatus was found in two patients. Both patients had a previous history of diabetes mellitus. Cultures from pacemaker pocket inflammatory fluid yielded positive results. Following pacemaker explantation and antifungal therapy, clinical improvement was achieved. A literature review showed another five cases of pacemaker infection due to Aspergillus. However, two peculiarities were found in our patients: In both cases an etiological diagnosis was achieved prior to surgery and, to the best of our knowledge, they also constitute the first cases of pacemaker pocket infection due to Aspergillus. CONCLUSION: Although pacemaker infections due to Aspergillus species are uncommon, they should be considered in immunocompromised patients.     

Dectin-1 agonist curdlan modulates innate immunity to Aspergillus fumigatus in human corneal epithelial cells

AIM: To explore the immunomodulatory effects of curdlan on innate immune responses against Aspergillus fumigatus (A. fumigatus) in cultured human corneal epithelial cells (HCECs), and whether C-type lectin receptor Dectin-1 mediates the immunomodulatory effects of curdlan.METHODS:The HCECs were stimulated by curdlan in different concentrations (50, 100, 200, 400 μg/mL) for various time. Then HCECs pretreated with or without laminarin (Dectin-1 blocker, 0.3 mg/mL) and curdlan were stimulated by A. fumigatus hyphae. The mRNA and protein production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined by real-timequantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The protein level of Dectin-1 was measured by Western blot.RESULTS: Curdlan stimulated mRNA expression of TNF-α and IL-6 in a dose and time dependent manner in HCECs. Curdlan pretreatment before A. fumigatus hyphae stimulation significantly enhanced the expression of TNF-α and IL-6 at mRNA and protein levels compared with A. fumigatus hyphae stimulation group (P<0.05). Both curdlan and A. fumigatus hyphae up-regulated Dectin-1 protein expression in HCECs, and Dectin-1 expression was elevated to 1.5- to 2-fold by curdlan pretreatment followed hyphaestimulation. The Dectin-1 blocker laminarin suppressed the mRNA expression and protein production of TNF-α and IL-6 induced by curdlan and hyphae (P<0.05).CONCLUSION:These findings demonstrated that curdlan pretreatment enhanced the inflammatory response induced by A. fumigatus hyphae in HCECs. Dectin-1 is essential for the immunomodulatory effects of curdlan. Curdlan may have high clinical application values in fungal keratitis treatment.     

Precipitins to an aflatoxin-producing strain of aspergillus flavus in patients with malignancy

Summary Serum samples from 121 patients in whom malignant disease had been diagnosed, were assayed for precipitins to fungal isolates from leukemia-associated environments. Control sera were from age-, sex-, and race-matched patients with no history of malignant disease. Sera from 36 (30%) malignancy patients and seven (6%) controls yielded a precipitin band to an aflatoxin-producing Aspergillus flavus isolate from a leukemia-associated house ², p<0.05%). No significant numbers of precipitins were obtained to either of the other fungal isolates from that and another such house.Although A. fumigatus has frequently been incriminated as a source of infection in patients with malignancy, only 9% of malignancy patients had a precipitin response to it, as did 1.6% of controls. Also, the presence of the precipitins to A. flavus was not connected with past radiation or imunosuppressive therapy. However, among patients with precipitins to A. fumigatus there was a higher death rate in the year following the study. Precipitins to A. flavus may be related to heavy environmental exposure possibly leading to aflatoxin exposure which may contribute to development of malignancy through immunosuppressive effects.