Medical Library

Isolation of beta-glucan from the cell wall of Saccharomyces cerevisiae.

beta-Glucan, one of the major cell wall components of Saccharomyces cerevisiae (S. cerevisiae), has been found to enhance immune functions. At present study, we developed an optimal procedure to extract and purify beta-glucan. At first, yeast cells were grown in sabouraud dextrose agar and then cultured in yeast extract-peptone-glucose (YPG) broth. After incubation, cells were harvested, washed and disrupted by means of sonication method. The obtained cell walls were used to prepare alkali-soluble beta-glucan (glucan-S(1)). In this regard, 2% sodium hydroxide (NaOH) and 3% acetic acid were used in alkaline-acid extraction, respectively. This preparation contained 2.4% protein. In the next step, DEAE sephacel chromatography was used to remove remaining proteins (glucan-S(2)). Subsequently this preparation was applied into concanavalin-A sepharose column to remove manann. Finally, beta-glucan free of mannoprotein complexes was prepared (glucan-S(3)).

Shokri H, Asadi F, Khosravi AR.

Mycology Research Center, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

Computational studies of Fe(III) binding to bryostatins, bryostatin analogs, siderophores and marine natural products: arguments for ferric complexes in medicinal applications.

In this computational study, geometric factors are calculated by applying semi-empirical methods (PM3) that support experimental evidence from this lab where bryostatins can bind trivalent iron with six Fe-O bonds forming an octahedral geometry. The geometric factors are calculated for all 20 structures (Fe(3+) bound to bryostatin 1-20) as a neutral, monovalent, and divalent species. The average Fe-O bond distances and bond angles are compared to those of known marine and terrestrial siderophores. From these two data sets, we then examined other known marine natural products (MNPs) that can form a hexavalent complex with six Fe-O bonds and draw conclusions about their potential biological role as marine siderophores. This computational data indicates that Fe(III) strongly bonds to a host of MNPs, increasing their water solubility, contracting their structure, hence allowing transport through cell membranes more readily, and in some cases, stabilizing ester bonds that are susceptible to hydrolysis. It is argued that administering medicinally bryostatin, its analogs or other MNPs as a ferric complex, holds some fundamental chemical advantages compared to its administration as a neutral uncomplexed species.

Manning TJ, Thomas J, Osiro S, Smith J, Abadi G, Noble L, Phillips D.

Department of Chemistry, Valdosta State University, Valdosta, GA 31698, USA.

Composition and antimicrobial activity of the essential oil of Acronychia pedunculata (L.) Miq. from Vietnam.

The chemical composition and the antimicrobial activity of the essential oil isolated from aerial parts of Acronychia pedunculata (L.) Miq. from Vietnam are reported. Analysis was carried out by GC (RI), GC-MS and (13)C NMR. Thirty-four compounds were identified, accounting for 92.8% of the oil. The major constituents were alpha-pinene (57.4%) and (E)-beta-caryophyllene (13.6%). The essential oil of A. pedunculata was shown to possess a broad spectrum of antimicrobial activity against various bacteria, particularly Salmonella enterica and Staphylococcus epidermidis.

Lesueur D, Serra Dde R, Bighelli A, Hoi TM, Thai TH, Casanova J.

Université de Corse, 20000 Ajaccio, France.

Synthesis and structure-activity relationship study of monotesone-A, an antifungal component of Monotes engleri.

The synthesis of (+/-)-monotesone-A, an antifungal component of Monotes engleri, as well as its four structural analogues were accomplished starting from the corresponding MOM-protected phloracetophenone and benzaldehyde derivatives. Antifungal activities of the five flavanone derivatives were studied against Candida albicans (14053 and ATCC 10231), Candida inconspicua, Candida dubliniensis and Candida krusei.

Kenéz A, Lestár Z, Lenkey B, Antus S.

Department of Organic Chemistry, University of Debrecen, Hungary.

A new benzofuranic acid from the leaves of Rhus alata.

From leaves of Rhus alata, one new benzofuranic acid named [(2E)-3-(4-hydroxy-5,7-dimethyl- benzo[3,4-b] furan-6-yloxy)-prop-2-enoic acid has been isolated together with eight known compounds: dimethyl ester of terephthalic acid, beta-amyrin, friedelin, lupeol, beta-sitosterol, oleanolic acid, taraxerone and ethyl gallate. Structural elucidations were done on the basis of chemical and physical data (IR, UV, (1)H-NMR, (13)C-NMR and MS spectra).

Parveena M, Basudan OA, Mushfiq M, Ghalib RM.

Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, U.P, India.

Disseminated fungal infection in a renal transplant recipient involving Macrophomina phaseolina and Scytalidium dimidiatum: case report and review of taxonomic changes among medically important members of the Botryosphaeriaceae.

We report the first case of human infection with the fungal plant pathogen Macrophomina phaseolina in a Sri Lankan-born Canadian man following a renal transplant in India. The patient subsequently succumbed to invasive infection with Scytalidium dimidiatum. Molecular sequence analysis confirmed the identification of both fungi and revealed that they are related species within the ascomycete family Botryosphaeriaceae. We review the rationale for the recent reclassification of S. dimidiatum as Neoscytalidium dimidiatum and of Nattrassia mangiferae (formerly considered a synanamorph of S. dimidiatum) as Neofusicoccum mangiferae. This and other recent cases illustrate the potential for plant pathogenic fungi to cause invasive human diseases which are refractory to antifungal therapy.

Tan DH, Sigler L, Gibas CF, Fong IW.

Division of Infectious Diseases, St Michael\’s Hospital, Toronto, Ontario.

Disseminated cryptococcosis with necrotizing fasciitis in an apparently immunocompetent host: a case report.

We present an unusual case of disseminated cryptococcosis with necrotizing fascitis in an immunocompetent host. The multi-system cryptococcal infection was proved using standard microbiological, histopathological and radiological investigations. After a combination of antifungal, antimicrobial and surgical therapy clinical cure was achieved.

Capoor MR, Khanna G, Malhotra R, Verma S, Nair D, Deb M, Aggarwal P.

Departments of Microbiology, Vardhman Mahaveer Medical College and Safdarjung Hospital, New Delhi, India.

Cholesterol dependent and Amphotericin B resistant isolates of a Candida glabrata strain from an Intensive Care Unit patient.

Here we report on two isolates of Candida glabrata recovered from urine samples collected from of an Intensive Care Unit patient. D1/D2 and ITS 1+2 rDNA sequence analysis confirmed its identification. The isolates were cholesterol dependent and resistant to Amphotericin B.

Rezusta A, Aspiroz C, Boekhout T, Cano JF, Theelen B, Guarro J, Rubio MC.

Departamento de Microbiología, Facultad de Ciencias de la Salud y del Deporte de Huesca, Spain.

Candida albicans metabolite affects the cytoskeleton and phagocytic activity of murine macrophages.

Candida albicans is the most common opportunistic fungal pathogen of humans, causing systemic disease in immunocompromised patients. Host resistance to C. albicans infections is mediated predominantly by neutrophils and monocytes/macrophages. We have previously shown that exposure of a human epithelial cell line (HEp2) to C. albicans or to a culture filtrate of C. albicans caused actin rearrangement in the HEp2 cells. Since shifting of actin from the filamentous to the globular form may be crucial to the activity of phagocytes, we assessed in the present study the effect of the C. albicans metabolite (lyophilized culture filtrate) on the cytoskeleton of murine peritoneal macrophages and on their phagocytic activity. Our results showed a significant decrease in phagocytosis of C. albicans, ranging from 53-63% and a 25% reduction for C. glabrata cells. Using confocal laser scanning microscopy an actin rearrangement in the macrophages could be demonstrated that may be associated with the decrease of phagocytosis. We also tested the effect of mannan and of the secreted aspartic proteinase (Sap) inhibitor - pepstatin, on the activity of the metabolite in order to define the putative component and found no influence. In conclusion, our data indicate that a C. albicans metabolite affects phagocytic activity of macrophages, probably by alterations in their cytoskeleton.

Schindler B, Segal E.

Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.

Human neutrophils susceptibility to Paracoccidioides brasiliensis: an ultrastructural and cytochemical assay.

Paracoccidioidomycosis, caused by the dimorphic fungus Paracoccidioides brasiliensis, is the most prevalent systemic mycosis of Latin America, with Brazil accounting for 80% of the reported cases. The great number of neutrophils found in P. brasiliensis granulomas demonstrates the importance of polymorphonuclear neutrophils (PMN) cells during this mycotic infection. It has been found that neutrophils from healthy human donors can ingest and kill the fungus through a typical phagocytic process. The present work tests the phagocytic ability of neutrophils collected from patients that had had and were considered cured of paracoccidioidomycosis. Transmission electron microscopy and cytochemical studies indicate that patients\’ neutrophils eventually degenerate during phagocytosis of P. brasiliensis. Endogen peroxidase and NAD(P)H-oxidase are activated during the process showing that the respiratory burst and the neutrophil degranulation are triggered by the attachment of the yeast cells. Apparently these processes are not enough to kill P. brasiliensis. Although fungicidal activity can be determined by colony forming unit (CFU) counting, qualitative data suggest, as noted, that neutrophils from patients with treated paracoccidioidomycosis degenerate during the phagocytosis process. Hence, this work demonstrates the existence of a functional neutrophil deficiency against P. brasiliensis in susceptible individuals. The exact origin of this susceptibility is still to be determined in further studies.

Dias MF, Mesquita J, Filgueira AL, De Souza W.

Hospital Universitário Clementino Fraga Filho, Departamento de Dermatologia.