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Biomedical subjects

R Rüchel

Publications and source records attributed to R Rüchel.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Rhinocerebral mucormycosis during deferoxamine therapy].

A 24-year-old woman had been in full remission of an acute myeloid leukaemia since 1988, but she required regular erythrocyte and platelet transfusions for pancytopenia. To counteract a progressive siderophilia due to the transfusions (ferritin levels of about 10,000 ng/ml) deferoxamine was intermittently given intravenously (5 g after each transfusion). Seven months after the start of this treatment the patient was hospitalized because of severe left-sided facial pain as well as reddening and swelling in the periorbital region. As maxillary and frontal sinusitis was suspected, antibiotics were administered (at first three times daily 2.2 g amoxicillin and clavulanic acid, then two times daily 300 mg rifampicin and 200 mg ciprofloxacin). Nonetheless, orbital phlegmon developed within a few days with protrusion and blindness of the left eye necessitating a decompression operation. Material obtained at operation revealed rhinocerebral mucormycosis. After 3 weeks of antimycotic treatment with both amphotericin B (1 mg/kg.d) and flucytosine (150 mg/kg.d) the mucormycosis healed without the necessity of extensive and disfiguring removal of necrotic tissue. But the blindness in the left eye, caused by occlusion of the central artery, was irreversible.

Adult↗
PubMed1991

Candidiasis visualised by proteinase-directed immunofluorescence.

The secretory aspartic proteinases of Candida albicans and C. tropicalis are potential factors for virulence produced during infection. By indirect immunofluorescence, we have demonstrated proteinase antigen on elements of both species in deparaffinized tissue sections derived from clinical cases of mucosal and deep-seated candidiasis. Occasionally, we observed a halo of fluorescence in the close vicinity of candidal cells, which may reflect secretion of the enzyme. In kidneys, a ring of amorphous fluorescent material surrounding candidal colonies may illustrate alkaline denaturation of secreted enzyme within a pH gradient, which is generated by the fungus. Our findings support the view that candidal proteinase may be a diagnostically relevant antigen.

Adult↗
PubMed1991

Sequence of the Candida albicans gene encoding the secretory aspartate proteinase.

The gene encoding the Candida albicans aspartate proteinase that is secreted by cells grown in protein-containing media was cloned from a C. albicans genomic bank. The base sequence of the insert shows a 1173 bp open-reading frame and indicates an amino acid sequence typical of aspartate proteinases, with amino acid sequence homology to other enzymes of this class and a putative signal peptide consisting of 50 amino acids upstream of the active enzyme.

Amino Acid Sequence↗
PubMed1991

[Pathogenicity of Candida albicans].

Candida albicans has an advantage on other fungal opportunists, being the only fungus among the normal microbial flora on human mucosa. The potential factors of virulence of C.albicans are essentially responsible for the persistence of the yeast on mucosal surfaces. If the normal regeneration of epithelia is impeded. C.albicans may invade the mucosa. It may penetrate deeply into the host during granulocytopenia or cellular immunodeficiency, apparently using mechanisms of mimicry and the activity of secretory hydrolases.

Antigens, Fungal↗
PubMed1990

Modulation of experimental systemic murine candidosis by intravenous pepstatin.

The effect of intravenous pepstatin-A on systemic candidosis in NWNI mice was investigated. True solutions of the inhibitor proved ineffective due to a very fast clearance. Pepstatin was effective as a crystal suspension (0.69 mg in 0.1 ml saline) which produced serum inhibitory activity for greater than 29 h. From the intravenously applied suspension, pepstatin was taken up predominantly into the liver, no inhibitor being taken up by the kidneys. The suspension was protective if it was injected once before the mice were infected and repeatedly following infection. It was also effective if it was administered concomitantly with the infecting agent and thereafter. The suspension was ineffective if it was only given once before infection, and it proved to be detrimental if it was given only after infection. The results support previous findings (2), suggesting a role of fungal proteinase early in the adherence of Candida to host epithelia. Our results also suggest an inhibition of lysosomal cathepsin-D in vivo by pepstatin, which prohibits a parenteral therapeutic use of nonmodified pepstatin A.

Animals↗
PubMed1990

Purification and characterisation of an extracellular serine proteinase from Aspergillus fumigatus and its detection in tissue.

A serine proteinase (Alp) from the culture supernate of a clinical isolate of Aspergillus fumigatus was purified to virtual homogeneity at a yield of 41%. The procedure involved affinity chromatography on agarose-epsilon-amino-caproyl-D-tryptophan methyl ester. Alp had an estimated mol. wt of 32 Kda and the pI was determined at pH 7.9. The enzyme was fully inhibited by phenylmethyl sulphonyl fluoride, chymostatin and alpha-1-proteinase inhibitor, and it was largely inhibited by alpha-1-anti-chymotrypsin. Partial inhibition was observed with tosyl-phenylalanine chloromethyl ketone, but tosyl-lysine chloromethyl ketone was ineffective. Thus, Alp may be identical with the major chymotryptic activity of A. fumigatus, which has already been described. The N-terminal sequence of 25 amino acids revealed an 88% homology of Alp with the subtilisin-related proteinase of A. oryzae. Alp acted on casein over a broad range from pH 5.5 to 11.5 and also acts to a lesser extent on haemoglobin and serum albumin. The enzyme degraded elastin and a synthetic elastase substrate; hence, it may be identical with the previously described elastinolytic activity of the fungus. At pH 7.3 and a concentration of 1 microgram/ml, Alp was not toxic for Vero cells, but it efficiently detached such cells from a plastic surface. Specific antibodies against Alp were detected by enzyme immunoassay in the sera of patients and Alp-antigen was demonstrated by immunofluorescence in mycotic human lung. In addition, a second proteinase (Exalp) with extremely alkaline activity, and an aspartic proteinase of A. fumigatus are described.

Amino Acid Sequence↗
PubMed1990

Topical fluconazole for experimental candida keratitis in rabbits.

Using a reproducible model of Candida albicans keratitis in rabbits we studied the effect of topical fluconazole, a new triazole. Candida albicans DSM 70010 (2.5 X 10(5) cells) was injected into the corneal stroma of both eyes of 21 rabbits. All eyes developed a corneal ulcer. Forty-eight hours after inoculation the animals were divided into three groups: (1) 14 eyes, received fluconazole (2 mg/ml) and the epithelium subsequently removed; (2) 14 eyes, received only fluconazole drops; (3) 14 eyes, received 0.9% NaCl: half of this group was also debrided. We applied one drop of either substance 10 times a day for 24 days. A further six rabbits were used to judge if the drug penetrated into the cornea and aqueous humour. There was a highly significant difference between the fluconazole groups (1,2) and the control group (3) as to hypopyon and complications (descemetocele, corneal perforation) as well as recultivation of C. albicans from corneal tissue. The difference between the fluconazole groups with and without debridement was not significant. The drug penetrated into the cornea and aqueous humour of both uninflamed and inflamed eyes.

Administration, Topical↗
PubMed1990

[The effect of selective decontamination on nosocomial infections, their causative agents and antibiotic resistance in long-term intubated intensive care patients].

During a 12-month period 45 long-term intubated patients were treated by topical application of non-absorbable antibiotics (tobramycin, polymyxin, amphotericin B) together with an initial short-term intravenous application of an antibiotic with only minimal activity against anaerobic intestinal flora. These patients were compared to 48 patients in the previous 12-month period who had only interventional antibiotic therapy in case of established infections. This selective decontamination of the digestive tract (SDD) reduced the colonisation of the respiratory tract, thus also decreasing incidence of nosocomial pneumonia. There were fewer urinary tract infections, while the incidence of wound infections and septicaemia was influenced to microorganism a lesser degree. The number of gram-negative isolated microorganism was reduced, leading to a shift towards gram-positive organisms, especially S. epidermidis. During the 12-month study period there was no change of antibiotic sensitivity of the isolated microorganisms. Although we encountered no problems associated with multiresistant pathogens, routine microbiological surveillance is strongly recommended to detect changes in antibiotic resistance at an early stage.

Administration, Topical↗
PubMed1990

Demonstration of fungal proteinase during phagocytosis of Candida albicans and Candida tropicalis.

The extracellular acid proteinase of Candida albicans and Candida tropicalis was monitored in vitro during phagocytosis by murine peritoneal macrophages. Fungal blastospores were quickly ingested by the thioglycolate-elicited macrophages and the intracellular blastospores partly resisted killing and started to grow out after 6 h incubation, causing destruction of the macrophage. Proteinase antigen appeared on fungal cells after 30 min in culture medium containing 10% fetal calf serum. The antigen was detected on ingested blastoconidia and filamentous cells of C. albicans serotype A. The proteinase antigen was also expressed by blastoconidia of C. albicans serotype B but was missing on the filamentous cells of this serotype. Isolates of C. tropicalis behaved similarly to C. albicans serotype A. The acid proteolytic activity of Candida cells was confirmed by the haemoglobin test on culture supernatants. Lysates of infected and noninfected phagocytes showed a differential acid proteolytic activity; noninfected macrophages revealed rising activity, while infected macrophages showed a distinct reduction of activity. The proteolytic activity of lysates of noninfected cells is due to lysosomal cathepsin-D. Cathepsin-D was also most likely to be responsible for the declining proteolytic activity in lysates from infected phagocytes; such lysates contained increasing amounts of fungal proteinase antigen. The differential kinetics of this antigen and the total acid proteolytic activity in the lysates suggest a conflict between microbial and lysosomal hydrolases in infected phagocytes. The outcome of this conflict depends on the number and hydrolytic activity of the ingested yeasts and may be decisive in the progress of infection.

Animals↗
PubMed1989

Candidosis: diagnostic tools in the laboratory.

The diagnosis of deep-seated candidosis still poses severe problems to the physician. While laboratory tests for a long time have been mainly based on the detection of antibodies to Candida and in particular Candida albicans the detection of Candida antigen in the blood gains more and more interest. When it comes to the evaluation of the various laboratory tests the correlation with autopsy data is most rewarding. The more specimens are analysed for the presence of hints at deep-seated candidosis in a given hospital setting the least frequent death due to deep-seated candidosis occurs.

Antibodies, Fungal↗
PubMed1988

Production and characterization of monoclonal antibodies against secretory proteinase of Candida albicans CBS 2730.

We describe the production and characterization of three murine monoclonal antibodies (M1-M3) which are directed against different epitopes of the secretory aspartic proteinase of Candida albicans CBS 2730. All antibodies belonged to the IgM class, and they recognized denatured enzyme. Only antibody M1 was capable to react with the active proteinase. Differential reactivity was also observed with a large fragment of the proteinase of C. albicans. All antibodies recognized the corresponding proteinase of C. tropicalis 293 both in the active, and in the denatured state. Denatured porcine pepsin was also recognized by all three antibodies. However, active pepsin was recognized only by antibodies M1 and M2. The antibodies did not inhibit enzymatic activity, and they were not suited for immunofluorescence detection of proteinase on fungal cells. However, employing Western blot analysis, proteinase antigen was detected by antibody M 1 in the serum of a patient suffering from candidal pneumonia. The circulating proteinase antigen was found to be bound to patient's IgM. Implications for the use of monoclonal antibodies in the serodiagnosis of candidosis, and first experiences with other monoclonal anti-proteinase antibodies are discussed.

Antibodies, Monoclonal↗
PubMed1988

Expression of extracellular acid proteinase by proteolytic Candida spp. during experimental infection of oral mucosa.

We traced an acid proteinase from Candida spp. in the initial stages of the pathogenesis of the mycosis. On infection of human buccal mucosa, proteinase antigens were detected by immuno-scanning electron microscopy on the surface of adhering blastoconidia and invading filamentous cells of C. albicans serotype A. Proteinase antigens were also present on blastoconidia of C. albicans serotype B, but were missing on filamentous cells of this serotype. Proteolytic isolates of C. tropicalis behaved like C. albicans serotype A. An isolate of C. parapsilosis did not express the proteinase antigen under conditions of this study. After infection of mucosa, culture medium of C. albicans or C. tropicalis showed a time-dependent accumulation of acid proteolytic activity, indicating that the visualized antigens represent active proteinase. No such activity was detected in the medium of C. parapsilosis. Preliminary experiments with the proteinase inhibitor pepstatin A revealed an 89% reduction of mucosal adherence of C. albicans (serotype A). These results suggest that Candida proteinase is involved in fungal attachment. The pattern of adherence reflects the differential expression of secretory proteinase by different candidal strains.

Candida↗