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Biomedical subjects

G Haase

Publications and source records attributed to G Haase.

At least 37 records · Page 2Linked to original sources
PubMed2001

Surgical complications after primary nephrectomy for Wilms' tumor: report from the National Wilms' Tumor Study Group.

BACKGROUND: Surgical complications are a recognized morbidity of the treatment of patients with Wilms tumor. This study examines the incidence of surgical complications in the most recently completed study from the National Wilms' Tumor Study Group (NWTSG). STUDY DESIGN: The fourth National Wilms' Tumor Study (NWTS-4) enrolled 3,335 patients from August 1986 to August 1994. A random sample of 534 patients was selected from 2,290 eligible patients randomized to treatment regimens or enrolled in the followed category and treated according to NWXTSG protocol. The patient records received at the NWTSG Data and Statistical Center were analyzed for surgical complications (intraoperative and postoperative). RESULTS: Sixty-eight patients (12.7%) experienced 76 complications. Intestinal obstruction was the most common complication (5.1% of patients), followed by extensive hemorrhage (1.9%), wound infection (1.9%), and vascular injury (1.5%). The incidence of surgical complications in NWTS-4 was significantly lower than NWTS-3 (12.7% versus 19.8%, p < 0.001). There has been a marked decrease in the risk of extensive intraoperative bleeding and major intraoperative complications. Factors previously shown to be associated with an increased risk for surgical complications, together with indicators of type of hospital and surgeon specialty, were analyzed by multiple logistic regression analysis. Intravascular extension into the inferior vena cava (IVC), the atrium, or both (p = 0.02; odds ratio [OR] 3.8, 95% confidence interval [CI] 1.2, 11.8), and nephrectomy performed through a flank or paramedian incision (p = 0.02; OR 5.3, 95% CI 1.3, 22) were both associated with increased risk of complications. Tumor diameter greater than or equal to 10cm was also associated with an increased risk of surgical complications (p = 0.05; OR 2.0, 95% CI 1.0, 3.9). The risk of complications was higher if the nephrectomy was performed by a general surgeon (OR 9.0, 95% CI 1.3, 65; p = 0.03) rather than a pediatric surgeon (reference group, OR 1.0) or pediatric urologist (OR 0.7, 95% CI 0.3, 1.8). CONCLUSIONS: The incidence of surgical complications in NWTSG patients undergoing primary nephrectomy has significantly decreased over the past decade. But surgical morbidity should not be overlooked. It is important that surgeons treating young children with solid tumors are aware of their role and the potential risks encountered in removal of the primary tumor. This study found that surgical specialists who primarily treat children can perform these operations with lower surgical morbidity.

Chemotherapy, Adjuvant↗
PubMed2001

Horizontal gene transfer and host specificity of beta-haemolytic streptococci: the role of a putative composite transposon containing scpB and lmb.

Beta-haemolytic streptococci are important human and animal pathogens: their genetic traits that are associated with the ability to infect human hosts remain, however, unclear. The surface protein, Lmb, mediates the adherence of Streptococcus agalactiae to human laminin. For further analysis of the corresponding gene, the adjacent genomic regions were sequenced. Lmb is localized on a putative composite transposon of 16 kb and is flanked by two copies of a novel insertion sequence element (ISSag2). It harbours the genes scpB and lmb, which are 98% identical with the respective genes of Streptococcus pyogenes. Analysis of the distribution of these genes and ISSag2 among 131 streptococcal strains revealed that all of the human isolates, but only 20% (12 of 61) of the animal isolates, contained scpB and lmb or their homologues. To investigate if the putative transposon can be mobilized, an erythromycin resistance marker was incorporated into the lmb gene of S. agalactiae. Screening for mutant strains with a regained susceptibility for erythromycin identified strains with a deletion of scpB, lmb, and one copy of ISSag2. We hypothesize that a horizontal gene transfer caused the exchange of scpB and lmb and that the ability of S. pyogenes, S. agalactiae and group C and G streptococcal strains to colonize or infect human hosts is dependent on their presence.

Adhesins, Bacterial↗
PubMed2001

Spinal muscular atrophy: present state.

Spinal muscular atrophy (SMA) is a hereditary neurodegenerative disease caused by homozygous deletions or mutations in the SMN1 gene on Chr.5q13. SMA spans from severe Werdnig-Hoffmann disease (SMA 1) to relatively benign Kugelberg-Welander disease (SMA 3). Onset before birth possibly aggravates the clinical course, because immature motoneurons do not show compensatory sprouting and collateral reinnervation, and motor units in SMA 1, in contrast to those in SMA 3, are not enlarged. Genetic evidence indicates that SMN2, a gene 99% identical to SMN1, can attenuate SMA severity: in patients, more SMN2 copies and higher SMN protein levels are correlated with milder SMA. There is evidence that SMN plays a role in motoneuron RNA metabolism, but it has also been linked to apoptosis. Several mouse models with motoneuron disease have been successfully treated with neurotrophic factors. None of these models is, however, homologous to SMA. Recently, genetic mouse models of SMA have been created by introducing human SMN2 transgenes into Smn knockout mice or by targeting the Smn gene knockout to neurons. These mice not only provide important insights into the pathogenesis of SMA but are also crucial for testing new therapeutic strategies. These include SMN gene transfer, molecules capable to up-regulate SMN expression and trophic or antiapoptotic factors.

Adenosine Triphosphatases↗
PubMed2001

Molecular cloning and characterization of WdPKS1, a gene involved in dihydroxynaphthalene melanin biosynthesis and virulence in Wangiella (Exophiala) dermatitidis.

1,8-Dihydroxynaphthalene (1,8-DHN) is a fungal polyketide that contributes to virulence when polymerized to 1,8-DHN melanin in the cell walls of Wangiella dermatitidis, an agent of phaeohyphomycosis in humans. To begin a genetic analysis of the initial synthetic steps leading to 1,8-DHN melanin biosynthesis, a 772-bp PCR product was amplified from genomic DNA using primers based on conserved regions of fungal polyketide synthases (Pks) known to produce the first cyclized 1,8-DHN-melanin pathway intermediate, 1,3,6,8-tetrahydroxynaphthalene. The cloned PCR product was then used as a targeting sequence to disrupt the putative polyketide synthase gene, WdPKS1, in W. dermatitidis. The resulting wdpks1Delta disruptants showed no morphological defects other than an albino phenotype and grew at the same rate as their black wild-type parent. Using a marker rescue approach, the intact WdPKS1 gene was then successfully recovered from two plasmids. The WdPKS1 gene was also isolated independently by complementation of the mel3 mutation in an albino mutant of W. dermatitidis using a cosmid library. Sequence analysis substantiated that WdPKS1 encoded a putative polyketide synthase (WdPks1p) in a single open reading frame consisting of three exons separated by two short introns. This conclusion was supported by the identification of highly conserved Pks domains for a beta-ketoacyl synthase, an acetyl-malonyl transferase, two acyl carrier proteins, and a thioesterase in the deduced amino acid sequence. Studies using a neutrophil killing assay and a mouse acute-infection model confirmed that all wdpks1Delta strains were less resistant to killing and less virulent, respectively, than their wild-type parent. Reconstitution of 1,8-DHN melanin biosynthesis in a wdpks1Delta strain reestablished its resistance to killing by neutrophils and its ability to cause fatal mouse infections.

Amino Acid Sequence↗
PubMed2001

Differentiation of Candida albicans and Candida dubliniensis by fluorescent in situ hybridization with peptide nucleic acid probes.

The recent discovery of Candida dubliniensis as a separate species that traditionally has been identified as Candida albicans has led to the development of a variety of biochemical and molecular methods for the differentiation of these two pathogenic yeasts. rRNA sequences are well-established phylogenetic markers, and probes targeting species-specific rRNA sequences have been used in diagnostic assays for the detection and identification of microorganisms. Peptide nucleic acid (PNA) is a DNA mimic with improved hybridization characteristics, and the neutral backbone of PNA probes offers significant advantages in whole-cell in situ hybridization assays. In this study, we developed PNA probes targeting the rRNAs of C. albicans and C. dubliniensis and applied them to a fluorescence in situ hybridization method (PNA FISH) for differentiation between C. albicans and C. dubliniensis. Liquid cultures were smeared onto microscope slides, heat fixed, and then hybridized for 30 min. Unhybridized PNA probe was removed by washing, and smears were examined by fluorescence microscopy. Evaluation of the PNA FISH method using smears of 79 C. dubliniensis and 70 C. albicans strains showed 100% sensitivity and 100% specificity for both PNA probes. We concluded that PNA FISH is a powerful tool for the differentiation of C. albicans and C. dubliniensis.

Candida↗
PubMed2001

Assessment of acid production by various human oral micro-organisms when palatinose or leucrose is utilized.

One promising way of reducing caries is by using sucrose substitutes in food, e.g., palatinose or leucrose. Previous experiments addressing cariogenic potential of sucrose substitutes have focused mainly on Streptococcus mutans. However, given the many other micro-organisms in the oral cavity, this study compared the acid production of 100 bacterial strains representing 44 different species, by batch fermentation in a test tube containing, as a sole carbohydrate source, glucose, sucrose, palatinose, or leucrose. Selected strains were further analyzed in a fermenter. Additionally, 30 yeast strains were tested by an auxanographic sugar assimilation test. Only Lactobacillus spp., Stomatococcus mucilaginosus, Leuconostoc mesenteroides, and Weissella paramesenteroides, and some of the yeasts studied-i.e., Candida albicans, C. tropicalis, C. parapsilosis, and Saccharomyces cerevisiae-utilized leucrose and/or palatinose well. Strikingly, Stomatococcus mucilaginosus produced water-insoluble polysaccharides by fermentation of leucrose and palatinose. In the fermenter, the respective sucrose substitutes were not only cleaved but also utilized. Thus, extracellular cleavage by autochthonous micro-organisms may produce cariogenic cleavage products (glucose, fructose) that can be used by other well-characterized cariogenic bacteria found in the oral flora. Therefore, the anticariogenic potential of sucrose substitutes in food might be limited.

Bacteria↗
PubMed2000

Phagocytosis, oxidative burst, and killing of Candida dubliniensis and Candida albicans by human neutrophils.

Candida dubliniensis is a phylogenetically closely related species to Candida albicans. So far virtually nothing is known about the virulence factors of C. dubliniensis. Cell surface hydrophobicity (CSH) plays a critical role in adhesion of microorganisms to phagocytic cells; hydrophobic cells of C. albicans have been reported to be less sensitive to phagocytic killing than hydrophilic cells. C. dubliniensis displays CSH at 37 degrees C in contrast to C. albicans. To elucidate this issue, we determined levels of phagocytosis, oxidative burst and killing by human neutrophils of C. dubliniensis (n=10) compared to C. albicans (n=10) both cultured at 37 degrees C. Obtained test results revealed no statistically significant differences between these two yeast species for the level of phagocytosis (77.3 vs. 76.2% after 60 min), evoked oxidative burst (64.5 vs. 67.3% after 30 min) and killing (72.7 vs. 73.1% after 240 min). Therefore, human neutrophils can be considered to be equally efficient against these two yeast species.

Candida↗
PubMed2000

GFRalpha 1 is required for development of distinct subpopulations of motoneuron.

Glial cell-line derived neurotrophic factor (GDNF) and its relative neurturin (NTN) are potent trophic factors for motoneurons. They exert their biological effects by activating the RET tyrosine kinase in the presence of a glycosyl-phosphatidylinositol-linked co-receptor, either GFRalpha1 or GFRalpha2. By whole-mount in situ hybridization on embryonic mouse spinal cord, we demonstrate that whereas Ret is expressed by nearly all motoneurons, Gfra1 and Gfra2 exhibit complex and distinct patterns of expression. Most motoneurons purified from Gfra1 null mutant mice had lost their responsiveness to both GDNF and NTN. However, a minority of them ( approximately 25%) retained their ability to respond to both factors, perhaps because they express GFRalpha2. Surprisingly, Gfra2(-/-) motoneurons showed normal survival responses to both GDNF and NTN. Thus, GFRalpha1, but not GFRalpha2, is absolutely required for the survival response of a majority of motoneurons to both GDNF and NTN. In accordance with the phenotype of the mutant motoneurons observed in culture we found the loss of distinct groups of motoneurons, identified by several markers, in the Gfra1(-/-) spinal cords but no gross defects in the Gfra2(-/-) mutant. During their natural programmed cell death period, motoneurons in the Gfra1(-/-) mutant mice undertook increased apoptosis. Taken together these findings support the existence of subpopulations of motoneuron with different trophic requirements, some of them being dependent on the GDNF family.

Animals↗
PubMed2000

Discriminative power of fatty acid methyl ester (FAME) analysis using the microbial identification system (MIS) for Candida (Torulopsis) glabrata and Saccharomyces cerevisiae.

Candida (Torulopsis) glabrata is frequently isolated in cases of fungal infection and commonly shows acquired or innate fluconazole resistance. Saccharomyces cerevisiae, an emerging opportunistic yeast pathogen, causes serious systemic infections in immunocompromised, and vaginitis and superficial infections in immunocompetent patients. For both species reliable identification in the routine laboratory is mandatory, but species identification of strains, e.g. trehalose-negative C. glabrata, may be difficult. Therefore, gas-liquid chromatography (GLC) of whole cell fatty acid methyl ester (FAME) profiles, that is independent of assimilation profiles of strains and suitable for reliable and rapid identification of clinically important yeasts, was applied. However, frequent misidentification of C. glabrata as S. cerevisiae has been reported when using the Yeast Clinical Database of MIS. Accuracy of MIS identification may be strongly influenced by the amounts of cell mass analyzed. Therefore, the present study compared the MIS results of these two yeasts achieved with different cell masses. Primarily we optimized, especially with respect to cost-effectiveness, the recommended streaking technique yielding a maximal recovery of 90-130 mg of cell mass from one plate, enabling testing of poor growing strains of C. glabrata. For all C. glabrata strains tested (n = 10) the highest identification scores (SI [Similarity Index] range 0.525-0.963, median 0.832) were achieved with 30 to 45 mg of cell mass. Only 5 of 10 S. cerevisiae strains revealed good library comparisons (SI > or = 0.5) when using 30 mg of cell mass, whereas with 45 mg all strains but two revealed this SI-level. For S. cerevisiae a higher amount of cell mass processed (up to 90 mg) was correlated with better identification scores (SI range using 90 mg: 0.464-0.870, median, 0.737). Several passages prior to FAME analysis of C. glabrata strains on recommended media revealed narrowing of SI ranges, but differences in SI values were not statistically significant.

Biomass↗
PubMed2000

Case report. Pathohistological findings in a clinical case of disseminated infection with Fusarium oxysporum.

Despite appropriate antimicrobial and antifungal therapy (amphotericin B), a disseminated infection with Fusarium oxysporum in a 75-year-old immunocompromised patient (acute myeloid leukaemia, minimal leucocyte count of 0.5 giga l-1) led rapidly to death. A similarly fatal course of an F. oxysporum infection has been reported in several cases. Fusarium oxysporum could be isolated shortly before death from blood cultures and from a swab taken from skin efflorescences. An autopsy revealed histopathologically typical fungal infiltrates in the mucosa of the pharynx, epiglottis, trachea, and oesophagus and in the parenchyma of the spleen, the lung and both kidneys. Because of the high risk of a fatal outcome of this infection, the clinician should aim at maximum diagnostic enforcement. We propose both analysis of blood cultures and immediate skin biopsy--with PAS-staining--of suspicious dermal efflorescences for microscopic examination. The treatment of choice is discussed controversially but a beneficial effect has been reported from granulocyte transfusion, subcutaneous administration of GM-CSF and concomitant treatment with amphotericin B.

Aged↗
PubMed2000

A new species, Phialophora europaea, causing superficial infections in humans.

A new species, Phialophora europaea, member of the P. verrucosa complex, is introduced. It is distinguished from existing species by reduced, flaring phialidic collarettes and inability to assimilate melibiose as sole source of carbon. Analysis of ITS1 and 2 rDNA of six strains attributed to the species show it to be clearly individualized. All strains originated from cutaneous and nail infections of humans in North-western Europe. A key to morphologically similar taxa is provided.

Child↗
PubMed2000

Differentiation between Candida dubliniensis and Candida albicans by fatty acid methyl ester analysis using gas-liquid chromatography.

Candida dubliniensis is often found in mixed culture with C. albicans, but its recognition is hampered as the color of its colonies in primary culture on CHROMagar Candida varies. Furthermore, definite identification of C. dubliniensis is difficult to achieve, time-consuming, and expensive. Therefore, a method to discriminate between these two closely related yeast species by fatty acid methyl ester (FAME) analysis using gas-liquid chromatography (Sherlock Microbial Identification System [MIS]; MIDI, Inc., Newark, Del.) was developed. Although the chromatograms of these two species revealed no obvious differences when applying FAME analysis, a new library (CADLIB) was successfully created using Sherlock Library Generation Software (MIDI). The amount and frequency of FAME was analyzed using library training files (n = 10 for each species), preferentially those comprising reference strains. For testing the performance of the CADLIB, clinical isolates genetically assigned to the respective species (C. albicans, n = 32; C. dubliniensis, n = 28) were chromatographically analyzed. For each isolate tested, MIS computed a similarity index (SI) indicating a hierarchy of possible strain fits. When using the newly created library CADLIB, the SIs for C. albicans and C. dubliniensis ranged from 0.11 to 0.96 and 0.53 to 0. 93 (for all but one), respectively. Only three isolates of C. albicans (9.4%) were misidentified as C. dubliniensis, whereas all isolates of C. dubliniensis were correctly identified. Resulting differentiation accuracy was 90.6% for C. albicans and 100% for C. dubliniensis. Cluster analysis and principal component analysis of the resulting FAME profiles showed two clearly distinguishable clusters matching up with two assigned species for the strains tested. Thus, the created library proved to be well suited to discriminate between these two species.

AIDS-Related Opportunistic Infections↗
PubMed2000

Evaluation of phenotypic markers for selection and identification of Candida dubliniensis.

Candida dubliniensis is often associated with C. albicans in cultures. Easy-to-perform selective isolation procedures for these closely related species do not exist. Therefore, we evaluated previously described discriminatory phenotypic markers for C. dubliniensis. A total of 150 oral rinses from human immunodeficiency virus (HIV)-infected patients were cultured on CHROMagar Candida. Dark green colonies described as being indicative of C. dubliniensis and other green colonies, 170 in total, were isolated. Chlamydospore formation, intracellular beta-D-glucosidase activity, ability to grow at 42 degrees C, carbohydrate assimilation pattern obtained by the API ID 32C, and Fourier transform infrared (FT-IR) spectroscopy were used for phenotypic characterization. Sequencing of the 5' end of the nuclear large-subunit (26S) ribosomal DNA gene was used for definitive species identification for C. dubliniensis. C. dubliniensis was found in 34% of yeast-colonized HIV-infected patients. The color of the colonies on CHROMagar Candida proved to be insufficient for selecting C. dubliniensis, since only 30 of 53 proven C. dubliniensis isolates showed a dark green color in primary cultures. The described typical chlamydospore formation can give only some indication of C. dubliniensis. The assimilation pattern proved to be insufficient to discriminate C. dubliniensis from C. albicans. All C. dubliniensis strains showed no or highly restricted growth at 42 degrees C and a lack of beta-D-glucosidase activity. Unfortunately, atypical C. albicans strains can also exhibit these phenotypic traits. FT-IR spectroscopy combined with hierarchical clustering proved to be as reliable as genotyping for discriminating the two species.

AIDS-Related Opportunistic Infections↗
PubMed2000

Investigation of infectious organisms causing pericoronitis of the mandibular third molar.

PURPOSE: The purpose of the study was to identify the most frequently encountered pyogenic organisms involved in pericoronitis to permit more targeted antibiotic therapy. PATIENTS AND METHODS: Pericoronal pockets of mandibular third molars from 37 patients showing symptoms of acute, severe pericoronitis were sampled and subjected to microbiologic analysis, including primary evaluation by phase-contrast microscopy. To avoid overgrowth with faster-growing, less fastidious organisms, specimens were cultured on a wide variety of selective media (supporting growth of fastidious bacteria, protozoa, and fungi). RESULTS: Microscopic examination indicated spirochetes in 55% and fusiform bacteria in 84% of the samples. A total of 441 microorganisms were isolated and identified from the 37 cultured samples. Besides obligate anaerobic bacteria, including various Actinomyces and Prevotella species, a predominantly facultative anaerobic microflora was cultivated, that is, Streptococcus milleri group (78% of samples), Stomatococcus mucilaginosus (71%), and Rothia dentocariosa (57%). CONCLUSION: It was concluded that the Streptococci milleri group bacteria, well-known for their ability to cause suppurative infections, are most likely involved in the pathogenesis of acute severe pericoronitis of the lower third molar.

Acute Disease↗
PubMed2000

Black fungi: clinical and pathogenic approaches.

Data are presented on the clinically relevant black yeasts and their relatives, i.e., members of the Ascomycete order Chaetothyriales. In order to understand the pathology of these fungi it is essential to know their natural ecological niche. From a relatively low degree of molecular variability of the black yeast Exophiala dermatitidis, potential agent of brain infections in patients from East Asia, it is concluded that this species is an emerging pathogen, currently going through a process of active speciation. It is found to be an oligotrophic fungus in hot, moist environments, such as steambaths. Cladophialophora-, Fonsecaea- and Ramichloridium-like strains, known in humans as agents of chromoblastomycosis, are frequently found on rotten plant material, but the fungal molecular diversity in the environment is much higher than that on the human patient, so that it is difficult to trace the etiological agents of the disease with precision. This approach has been successful with Cladophialophora carrionii, of which cells resembling muriform cells, the tissue form of chromoblastomycosis, were found to occur in drying spines of cacti. Phagocytosis assays provide a method to distinguish between pathogens and non-pathogens, as the killing rates of strict saprobes proved to be consistently higher than of those species frequently known as agents of disease. The therapeutic possibilities for patients with chromoblastomycosis are reviewed.

Antifungal Agents↗
PubMed1999

Novel microtiter plate format for testing germ tube formation and proposal of a cost-effective scheme for yeast identification in a clinical laboratory.

The germ tube test is most widely used for presumptive identification of Candida albicans. Conventional testing is relatively time-consuming due to the hands-on time involved in preparing and viewing each isolate. In order to reduce work-load and costs we have developed a novel microtiter plate test format that offers several advantages: (i) use of removable strips of microtiter wells placed in lockwell frames, (ii) only one pipetting step for each isolate, (iii) direct micromorphological evaluation using an inverse microscope, (iv) use of a novel synthetic germ tube test medium, (v) reduction of the inoculum, permitting testing of minute colonies, (vi) thus, testing of different colonies in potentially mixed primary cultures of clinical specimens is encouraged and facilitated. Implementing this microtiter based germ tube test with simultaneous trehalase test for presumptive identification of Torulopsis (Candida) glabrata, we propose an identification scheme including this test format. This has been implemented in our routine laboratory permitting cost-effective presumptive identification of almost all clinically relevant yeast species.

Candida↗