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K Lemmer

Publications and source records attributed to K Lemmer.

12 recordsLinked to original sources
PubMed2004

Molecular typing of Cryptococcus neoformans by PCR fingerprinting, in comparison with serotyping and Fourier transform infrared-spectroscopy-based phenotyping.

Molecular typing by PCR fingerprinting using the single primer (GACA)4 was performed with 110 isolates of Cryptococcus neoformans. Seventy clinical isolates of C. neoformans var. neoformans from Germany (n = 52) and Africa (n = 18) were included. Of these, serotype A (C. neoformans var. grubii) accounted for 47 isolates, serotype D for 12 and serotype AD for 11. Fourier transform infrared (FT-IR) spectroscopy was evaluated for its discriminatory power in phenotyping. Molecular types, defined by different PCR fingerprinting patterns, were compared to serotypes, and both sets of results were compared with the results of analysis by FT-IR spectroscopy. PCR fingerprinting revealed genotypic diversity within each serotype; it showed three different genotypes (designated VNA1-VNA3) within serotype A, two within serotype D (VND1 and VND2), and three within serotype AD (VNAD1-VNAD3). The nomenclature of molecular types within C. n. var. neoformans, as seen in publications to date, is not uniform. In this study, the name assigned to each genotype was based on the 98.6% concordance of genotypes with serotypes, a correspondence that facilitates interlaboratory comparison. This nomenclature is tentatively recommended as a standard. FT-IR spectroscopy combined with hierarchical cluster analysis successfully distinguished C n. var. neoformans from C. n. var. gattii. For C. n. var. neoformans, FT-IR confirmed three distinct genotypes within serotype A and was able to distinguish isolates derived from particular patients as well as isolates differing at the sub-genotype level. Within C. n. var. gattii, the serotypes B and C did not correlate with the four genotypes VGI-VGIV. However, these serotypes could clearly be separated by FT-IR spectroscopy. The molecular profiles were reproducible, and were more stable and more discriminating than serotyping. In connection with a standardized nomenclature, PCR fingerprinting can be a beneficial tool for global epidemiological studies. FT-IR spectroscopy adds an additional level of resolution.

Bacterial Typing Techniques↗
PubMed2004

Follow-up of epidemiological data of cryptococcosis in Austria, Germany and Switzerland with special focus on the characterization of clinical isolates.

The present survey in Austria, Germany and Switzerland continued the survey of cryptococcosis set up by the European Confederation of Medical Mycology (ECMM) in 1997. From 2000 to 2003 77 cases have been reported. An HIV infection is still the most important risk factor (68%). Young HIV+ women from ASIA contributed to the increase of cryptococcosis in females. A total of 129 clinical isolates of both surveys were genotyped by PCR fingerprinting to study the prevalence of different genotypes. The prevalence of Cryptococcus neoformans var. grubii (serotype A) with the genotypes VNA1 and VNA2 was higher in Germany and Austria (74.5%) than in Switzerland (52%), while in Switzerland the Cr. neoformans hybrids AD (26%) and Cr. neoformans var. neoformans (serotype D) (22%) were more prevalent compared with Germany and Austria (8 and 17.5% respectively). Cryptococcus gattii isolates were studied by FT-IR spectroscopy. DNA in the ITS region was sequenced to get further information about Cr. neoformans serotype AD strains and about the geographical origin of the Cr. gattii isolates. The ITS sequence of the serotype AD isolates of the genotypes VNAD1, VNAD2 and VNAD4 is usually identical to serotype A or serotype D respectively. In the three isolates of the genotype VNAD3 a genotype-specific sequence pattern was detected. Two autochthonous infections due to Cr. gattii could indicate that the genotype VGIV with the ITS type 'Asia 2' might be endemic in Europe.

Adult↗
PubMed2002

Expression of dopamine receptors and transporter in neuroendocrine gastrointestinal tumor cells.

C-11- or F-18-DOPA positron emission tomography (DOPA PET) is a new sensitive imaging technique for small neuroendocrine gastrointestinal tumors which evaluates the decarboxylase activity. To further characterize the dopaminergic system in neuroendocrine gastrointestinal tumor cells, we investigated the expression of both dopamine receptors and the transmembrane dopamine transporter (DAT) in the human neuroendocrine pancreatic cell line BON and in the neuroendocrine gut cell line STC-1. Both BON and STC-1 cells expressed mRNA of the dopamine receptors D2-D5 and DAT. mRNA of the dopamine receptor D1 was detected in BON cells only. Both in BON and STC-1 cells, expression of D2 and D5 receptors and DAT was also demonstrated immunocytochemically. For functional receptor characterization intracellular cAMP levels ([cAMP]i) were determined. Whereas in STC-1 cells dopamine and the D1-like (D1/D5) receptor agonist SKF 38393 increased [cAMP]i, [cAMP]i was decreased by dopamine or the D2-like (D2-D4) receptor agonist quinpirole in BON cells. Functional DAT activity was, however, not detected in either cell line. The presence of both dopamine receptors and of the DAT suggests an autocrine and/or paracrine function of dopamine in neuroendocrine gastrointestinal tumor cells. Yet neither the transmembrane dopamine transporter nor dopamine receptors are likely to contribute to positive DOPA PET imaging of neuroendocrine gastrointestinal tumors. However, these molecules may be of diagnostic importance when applying other dopaminergic system tracers.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2002

A case of imported paracoccidioidomycosis in a German legionnaire.

We report on a case of the chronic form of paracoccidioidomycosis with swelling and ulcerations of the mouth in a German legionnaire who also suffered from a chronic bronchitis. The patient had worked for many years in Brazil, an area endemic for the disease. Infection due to Paracoccidioides brasiliensis was diagnosed in Germany, more than 10 years after the patient's return. Diagnosis was established by the presence of yeast cells with multipolar budding in the tissue of the oral lesion. Furthermore, the fungus was grown in a liquid Leishmania culture medium. Identification of the fungus was based on morphology and genetic sequencing. Furthermore, IgG antibodies against a 43-kDa antigen of P. brasiliensis were detected in a western blot. After itraconazole therapy (400 mg day(-1)) for 4 weeks, the lesions had disappeared almost completely, but the therapy was continued for further 5 months to avoid relapse of the infection.

Antifungal Agents↗
PubMed1998

Expression of functional GABAA receptors in isolated human insulinoma cells.

Pancreatic islets contain and release high concentrations of GABA. GABA is thought to play a paracrine role in beta-cells. Searching for a paracrine function of GABA in neoplastic beta-cells we performed patch-clamp studies in isolated human insulinoma cells. We show that human insulinoma cells can express functional GABAA receptors. Activation of GABAA receptors caused a reversible membrane depolarization in a subgroup of insulinoma cells. Membrane depolarization resulted in transmembraneous calcium influx through voltage-gated calcium channels and stimulation of insulin secretion. Insulin secretion was increased by the GABAA receptor agonist muscimol (50 microM) by about 280%. Thus, GABAA receptors can be expressed in human insulinoma cells and can regulate their insulin release.

Cadmium Chloride↗
PubMed1998

Expression of functional P2-purinergic receptors in primary cultures of human colorectal carcinoma cells.

Primary cell cultures of human colorectal carcinomas were established and characterized immunocytochemically. In the isolated cancer cells intracellular Ca2+ concentrations ([Ca2+]i) were measured by the fura-2 method. Stimulation with either extracellular ATP or UTP caused a biphasic rise of [Ca2+]i in a dose-dependent manner and cross-desensitization between both nucleotides was observed. The rank order of potency was ATP >== UTP > ATP-gamma-S > ADP > adenosine which is characteristic for a P2U-receptor subtype. Selective agonists of P1-, or P2X- purinoceptors had no effect on [Ca2+]i. The initial rise in [Ca2+]i was independent of extracellular calcium [Ca2+]e, whereas the second phase was not observed under [Ca2+]e-free conditions suggesting a capacitative Ca2+-entry-mechanism. Intracellular Ca2+ mobilization was proven by use of the Ca2+-ATPase inhibitor thapsigargin. P2U-specific mRNA could be detected by RT-PCR in both colorectal tumor tissues and in the human colorectal cancer cell line HT 29. In HT 29 cells, the hydrolysis-resistant ATP analog ATP-gamma-S inhibited cell proliferation and, also, induced apoptosis in a dose-dependent manner. Thus, human colorectal cancer cells express functional P2U-receptors which may play a role in the regulation of cell proliferation and apoptosis.

Adenosine Triphosphate↗
PubMed1998

Expression of functional GABAA receptors in cholecystokinin-secreting gut neuroendocrine murine STC-1 cells.

1. Gastrointestinal neuroendocrine (NE) cells synthesize, store and secrete gamma-aminobutyric acid (GABA). Recently, an autocrine-paracrine function of GABA has been proposed for secretion from NE cells. 2. To search for functional GABAA receptors in NE gut cells, we performed whole-cell and perforated-patch-clamp studies in the intestinal cholecystokinin (CCK)-secreting NE cell line STC-1. 3. Application of GABA evoked currents in STC-1 cells. These effects were mimicked by muscimol, an agonist of GABAA receptors, and blocked by picrotoxin or bicuculline, antagonists of GABAA receptors. The GABA- or muscimol-activated currents reversed near 0 mV, which under the recording conditions used was consistent with the activation of the GABAA receptor-Cl- channel complex. 4. In contrast to the effect on most neurons, GABA as well as muscimol led to a (reversible) depolarization of the membrane potential of STC-1 cells. Membrane depolarization in turn activated voltage-gated Ca2+ channels and increased intracellular Ca2+ concentrations in STC-1 cells. 5. In accordance with the observed membrane depolarization and activation of voltage-gated Ca2+ channels, both GABA and muscimol stimulated Ca2+-dependent CCK release. In contrast, bicuculline inhibited the GABA-induced secretion of CCK. 6. Using the reverse transcription-polymerase chain reaction (RT-PCR), mRNA of the GABAA receptor subunits alpha2, alpha3, alpha5, beta1, beta3 and delta could be detected in STC-1 cells. 7. In summary, we have shown that the CCK-secreting gut NE cell line STC-1 expresses functional GABAA receptors and that GABA stimulates CCK release. Thus, GABA is involved in the fine tuning of CCK secretion from the gut NE cell line STC-1.

Animals↗