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G Frey

Publications and source records attributed to G Frey.

At least 19 recordsLinked to original sources
PubMed2001

Modulation of recombinant human prostate-specific antigen: activation by Hofmeister salts and inhibition by azapeptides. Appendix: thermodynamic interpretation of the activation by concentrated salts.

Prostate specific antigen (PSA, also known as human kallikrein 3) is an important diagnostic indicator of prostatic disease. PSA exhibits low protease activity (>10(4)-fold less than chymotrypsin) under the usual in vitro assay conditions. In addition, PSA does not react readily with prototypical serine protease inactivators. We expressed human PSA (rh-PSA) in Escherichia coli and have demonstrated that rh-PSA has properties similar to those of native PSA isolated from human seminal fluid. Both PSA and rh-PSA are >10(3)-fold more active in the presence of 1.3 M Na(2)SO(4). This activation is anion-dependent, following the Hofmeister series when normality is considered: SO(4)(2)(-) approximately citrate > Ac(-) > Cl(-) > Br(-) > I(-). The nature of the cation has little effect on salt activation. The rate of inactivation of rh-PSA by DFP is 30-fold faster in the presence of 0.9 M Na(2)SO(4), and the rate of inactivation by Suc-Ala-Ala-Pro-Phe-CK is >20-fold faster under these conditions. Azapeptides containing Phe or Tyr at position P(1) also inactivate rh-PSA in the presence of high salt concentrations. These compounds represent the first described inhibitors designed to utilize the substrate binding subsites of PSA. CD spectroscopy demonstrates that the conformation of rh-PSA changes in the presence of high salt concentrations. Analytical ultracentifugation and dynamic light scattering indicate that PSA remains monomeric under high-salt conditions. Interestingly, human prostatic fluid contains as much as 150 micro mol citrate/g wet weight, which suggests that salt concentrations may regulate PSA activity in vivo.

Base Sequence↗
PubMed2001

Chylothorax complicating Gorham's disease.

Gorham's disease is a rare disorder characterized by a proliferation of thin-walled lymphatic vessels (lymphangiectasia) resulting in an osteolysis. A chylothorax is present in about one-fifth of the patients and carries a poor prognosis. In this circumstance, surgery including thoracic duct ligation, pleurodesis, and excision of involved tissue is probably the treatment of choice. It is facilitated by a precise radiological assessment using a computed tomographic scanning coupled with a lymphography. We report such a case.

Chylothorax↗
PubMed2001

Differential gene expression profile of glucocorticoids, testosterone, and dehydroepiandrosterone in human cells.

Glucocorticoids are the major immunomodulating hormones in the human body. Recently, increasing interest in androgens as immunomodulators has emerged. In particular, Dehydroepiandrosterone (DHEA) has been suggested as beneficial in the treatment of some autoimmune disorders. However, the action and role of testicular and adrenal androgens on human immune cells remains unclear. This is the first study to provide large-scale gene expression data on the action of different steroids (DHEA, glucocorticoids, and testosterone) on human peripheral blood mononuclear cells using the recently developed genomic-scale technology of microarrays. Novel computational tools and techniques such as Principal Component Analysis (PCA) were used for analysis, clustering and visualization. We have demonstrated that each steroid has its distinct gene expression profile, although DHEA and testosterone co-regulated most genes in a similar direction while glucocorticoids frequently regulated the same genes in an opposite direction. Our data suggest an important and a complex regulatory role for androgens on human immune cells that should be considered in androgen replacement or treatment strategies.

Dehydroepiandrosterone↗
PubMed2000

NCAM (neural cell adhesion molecules) expression in malignant mesotheliomas.

Neural cell adhesion molecules (NCAM) are adhesion molecules expressed by neural and neuroendocrine tumors and a few biphasic tumors such as synovialosarcomas and breast phyllode tumors. To investigate NCAM expression in mesotheliomas, we studied 26 cases of epithelioid (n = 12), biphasic (n = 11), and sarcomatoid (n = 3) malignant mesotheliomas (MM), in comparison with normal mesothelium, and 50 primary non-small cell lung carcinomas (NSCLC) (25 adenocarcinomas [ADC] and 25 squamous cell carcinomas [SCC]), using electron microscopy as a gold standard for recognition of MM. NCAM reactivity using 123C3 antibody was compared with that of NE markers such as chromogranin A and synaptophysin. Although normal mesothelium remains negative, NCAM was expressed in 19 of 26 MM (73%) with a membranous staining on frozen or paraffin sections. In 6 of 12 epithelioid MM, the tumor cells expressed NCAM, whereas in 5 cases stromal fibroblasts showed a strong but focal staining. In 11 biphasic MM, 4 presented an NCAM reactivity of both epithelioid and spindle cell components, whereas in 7, only fusiform component was NCAM positive. Two of 3 sarcomatoid MM showed an NCAM expression. Chromogranin expression was never seen, whereas synaptophysin was noticed in 2 cases. No case of NSCLC showed membranous 123C3 staining, whereas 2 ADC weakly expressed synaptophysin. We conclude that NCAM expression in MM is reminiscent of its expression in mesoderm during fetal life and consistent with that reported in other biphasic tumors. These data show that NCAM expression occurs in 73% of MM, highly exceeding that observed in lung cancer.

Adenocarcinoma↗
PubMed1999

The recombinant thermosome from the hyperthermophilic archaeon Methanopyrus kandleri: in vitro analysis of its chaperone activity.

The archaeon Methanopyrus kandleri is the most thermophilic methanogen presently known. It contains a chaperonin (thermosome) which represents a 951 kDa homo-hexadecameric protein complex with NH4+-dependent ATPase activity. Since its synthesis is not increased upon heat shock, we set out to test its chaperone function. In order to obtain the chaperonin in amounts sufficient for functional investigations, the gene encoding the 60 kDa subunit was expressed in E. coili BL21 (DE3) cells. Purification yielded soluble, high-molecular-mass double-ring complexes, indistinguishable from the natural thermosome. In order to study the functional properties of the recombinant protein complex, pig citrate synthase, yeast alcohol dehydrogenase, yeast alpha-glucosidase, bovine insulin, and Thermotoga phosphoglycerate kinase were used as model substrates. The results demonstrate that the recombinant M. kandleri thermosome possesses a chaperone-like activity in vitro, inhibiting aggregation as the major off-pathway-reaction during thermal unfolding and refolding of proteins after chemical denaturation. However, the chaperonin only forms dead-end complexes with its non-native substrates, no release is detectable at temperatures between 25 and 60 degrees C.

Alcohol Dehydrogenase↗
PubMed1998

Recombinant homo- and hetero-oligomers of an ultrastable chaperonin from the archaeon Pyrodictium occultum show chaperone activity in vitro.

The archaeon Pyrodictium occultum is one of the most thermophilic organisms presently known. Previous experiments provided support for the significant contribution of a high-molecular-mass protein complex to the extreme thermotolerance of P. occultum. This protein complex, the 'thermosome', is composed of two subunits, alpha and beta, which form a hexadecameric double ring complex. In order to obtain the thermosome in amounts sufficient for structural and functional investigations, we produced the two subunits jointly and separately in Escherichia coli BL21(DE3). In all three cases, we isolated soluble, high-molecular-mass double-ring complexes from E. coli BL21(DE3). On electron micrographs, the recombinant complexes were indistinguishable from each other and from the natural thermosome. To characterize the quaternary structure of the recombinant particles, we used native gel electrophoresis, analytical gel filtration, and analytical ultracentrifugation. Spectral analysis, using absorption, fluorescence emission and far-UV circular dichroism spectroscopy were applied to compare the three recombinant protein complexes with the natural thermosome from P. occultum. All three recombinant complex species exhibit ATPase activity. Furthermore, we could demonstrate that the recombinant complexes slow down the aggregation of citrate synthase, alcohol dehydrogenase, and insulin. Thus, we conclude that the recombinant protein complexes exhibit a chaperone-like activity, interacting with non-native proteins; they do so at temperatures far below the lower physiological limit of growth.

Adenosine Triphosphatases↗
PubMed1998

ATP-inhibited K+ channels and membrane potential of identified leech neurons.

The effect of the ATP-inhibited K+ channel on the membrane potential of leech Retzius neurons was analyzed using electrolyte-filled single-barrelled microelectrodes. The membrane potential was independent of the external nutrient supply during a period of 11 h, probably because the internal energy reserves were sufficient. The K+ channel activator HOE 234 ((3S,4R)-3-hydroxy-2, 2-dimethyl-4-(2-oxo-1-pyrrolidinyl)-6-phenylsulfonylchromane hemihydrate, 500 microM) induced a membrane hyperpolarization. In the presence of HOE 234, action potentials occurred with a reduced after-hyperpolarization and were discharged in bursts, possibly because of an inhibition of Ca2+ channels. The blocker of ATP-inhibited K+ channels tolbutamide did not significantly alter the membrane potential. In the absence of tolbutamide, the metabolic inhibitors iodoacetate, azide and cyanide (10 mM) evoked membrane hyperpolarizations, but in the presence of 1 mM tolbutamide their hyperpolarizing actions were reduced or abolished while membrane depolarizations were intensified. We conclude that ATP-inhibited K+ channels in the soma membrane of leech Retzius neurons provide coupling of cellular metabolism to electrical activity and ionic fluxes.

ATP-Binding Cassette Transporters↗
PubMed1998

The thermosome from Methanopyrus kandleri possesses an NH4+-dependent ATPase activity.

The ATPase activity of the thermosome from a methanogen, Methanopyrus kandleri, was characterized in detail. In contrast to all other known chaperonins, enzymatic ATP hydrolysis was found to be strictly dependent on high levels of ammonium salts in vitro. The ths gene encoding the thermosome subunit from the hyperthermophilic M. kandleri was functionally expressed in Escherichia coli and the overproduced polypeptide was assembled into intact thermosome complexes in the mesophilic host. The recombinant particles could be purified by a simple two-step procedure including only one chromatographic step. Structural and biochemical properties of the recombinant protein were closely similar to those of the natural complex. Western blot analysis with an antiserum against the M. kandleri thermosome indicated the presence of at least two subfamilies of archaeal chaperonins.

Adenosine Triphosphatases↗
PubMed1998

Purification and properties of an extremely thermostable membrane-bound sulfur-reducing complex from the hyperthermophilic Pyrodictium abyssi.

The chemolithoautotrophic archaeon Pyrodictium abyssi isolate TAG 11 gains energy by reducing sulfur with H2 to H2S. From this hyperthermophile, a sulfur-reducing complex catalyzing this reaction was purified 13.5-fold. The native complex exhibited a brownish-yellow colour and showed an apparent molecular mass of 520 kDa. SDS/PAGE revealed the presence of nine different major polypeptides with apparent molecular masses of 82, 72, 65, 50, 47, 42, 40, 30 and 24 kDa. The native complex contained 50-55 mol acid-labile sulfur, 50-55 mol iron, 1.6 mol nickel, 1.2 mol copper, 2.8 mol cytochrome b and 0.3 mol cytochrome c (all per mol native complex). The temperature optimum of the H2:sulfur oxidoreductase complex was 100 degrees C, which is consistent with the physiological growth optimum of the native organism. The complex is extremely heat stable. During 5 h incubation at 100 degrees C, no decrease in H2S-forming activity could be observed.

Amino Acid Sequence↗
PubMed1998

[Hyperbaric oxygenation. An area for the anesthetist?].

Hyperbaric Oxygen (HBO) therapy is a kind of medical treatment in which a patient breathes 100% of oxygen inside a pressure chamber while the pressure of the chamber is increased to a point higher than sea level pressure. It is strongly based on clearly defined physical laws and physiological regularities. For the clinical use of HBO therapy, according to international recommendations, there are several commonly accepted indications in which HBO either is the only causative life-saving kind of treatment, or is an essential and oftenly decisive component of a comprehensive interdisciplinary intensive care therapy. Among potential adverse effects, barotrauma of the lungs and especially oxygen toxicity to the central nervous system have to be mentioned. Clinical use of HBO therefore requires special knowledge of its effects, risks, and adverse effects, a clear and distinct indication, and the ability and skills to keep complications under control by means of intensive care or emergency medical measures. The clinical use of hyperbaric oxygen with its interdisciplinary-like character of emergency medicine or intensive care therapy therefore should be an additional, most interesting field of activity for the anaesthesiologist.

Anesthesiology↗
PubMed1998

Prevalence and determinants of house dust mite allergen in East German homes.

BACKGROUND: In 1990/91, allergic sensitization to house dust mites (HDM) and other allergens was more prevalent in children from West Germany than from East Germany. OBJECTIVE: To test the hypothesis that low indoor exposure to HDM allergen in East Germany has contributed to this difference. METHODS: HDM allergen concentrations were determined in 634 East German dwellings shortly after the German reunification. RESULTS: HDM group I allergen (Der p 1 + Der f 1) levels in mattresses (median 2.16, geometric mean 2.07, maximum 278.9 microg/g dust) and carpets (median 0.41, geometric mean 0.48, maximum 96.3 microg/g dust) were within the range of levels determined in West Germany in other studies. One particular East German type of dwelling (light concrete buildings) was associated with lower mite allergen exposure, but only a minority of the population lived there. Coal heating, installed in the majority of dwellings before 1989, was associated with higher allergen exposure. Higher relative humidity (RH) was a main risk factor for higher Der p 1 exposure (odds ratio [OR] for exposure to > 0.05 microg/g dust on carpets: 1.4 [95% confidence interval (CI) 1.2-1.8] for + 10% RH) but not for higher Der f 1 exposure. Higher temperature was associated with a lower risk for elevated Der p 1 levels (> 0.05 microg/g dust on carpets): OR 0.6 (95% CI 0.5-0.8) for + 2 degrees C. CONCLUSION: Mite allergen exposure is not lower in East Germany than in West Germany. The data does not support the hypothesis, that low HDM allergen exposure in East Germany is a cause for the lower prevalence of HDM sensitization in East German children.

Adult↗
PubMed1998

Molecular cloning and functional expression of a protein-serine/threonine phosphatase from the hyperthermophilic archaeon Pyrodictium abyssi TAG11.

An open reading frame coding for a putative protein-serine/threonine phosphatase was identified in the hyperthermophilic archaeon Pyrodictium abyssi TAG11 and named Py-PP1. Py-PP1 was expressed in Escherichia coli, purified from inclusion bodies, and biochemically characterized. The phosphatase gene is part of an operon which may provide, for the first time, insight into a physiological role for archaeal protein phosphatases in vivo.

Amino Acid Sequence↗
PubMed1997

HMGIC expressed in a uterine leiomyoma with a deletion of the long arm of chromosome 7 along with a 12q14-15 rearrangement but not in tumors showing del(7) as the sole cytogenetic abnormality.

Cytogenetic studies on uterine leiomyomas have shown that more than 60% of these tumors possess a normal karyotype and that 30% have clonal chromosomal aberrations. The most frequent changes are aberrations involving 12q14-15 and show rearrangements of the long arm of chromosome 7. Recently, we were able to demonstrate that in a variety of mesenchymal tumors showing 12q14-15 aberrations the HMGIC gene is rearranged thus playing a role in tumorigenesis. Here we report the results of HMGIC expression studies by RT-PCR of five uterine leiomyomas with different karyotypes. The RT-PCR studies were performed on two primary tumors showing a 12q14-15 aberration, one of which with an additional del(7) and three tumors with del(7) as the sole aberration. The tumor with the 12q14-15 aberration as the sole alteration and the leiomyoma with 12q14-15 rearrangement plus deletion of the long arm of chromosome 7 were shown to express HMGIC. In contrast, in all three tumors with the del(7) as the sole aberration no expression of HMGIC was noted.

Chromosome Aberrations↗
PubMed1996

Purification and structural characterization of the thermosome from the hyperthermophilic archaeum Methanopyrus kandleri.

From Methanopyrus kandleri, the most thermophilic methanogen known so far, we have purified to homogeneity a protein complex of high molecular mass. Image analysis of transmission electron micrographs revealed a barrel-shaped particle composed of two rings with 8-fold symmetry. Only one type of subunit could be detected. The corresponding gene has been cloned and sequenced. The deduced amino acid sequence shows high homology with the members of group II chaperonins. The structure of the projection and the sequence homology suggest that this particle is the first thermosome isolated from a methanogen.

Amino Acid Sequence↗
PubMed1996

Single K+ channels in embryonic leech ganglion cells.

We investigated the properties of single K+ channels in the soma membrane of embryonic leech ganglion cells using the patch-clamp technique. We compared these K+ channels with the K+ channels found previously in Retzius neurons of the adult leech. In ganglion cells of 9- to 15-day-old embryos we characterized eight different types of K+ channels with mean conductances of 21, 55, 84, 111, 122, 132, 149 and 223 pS. The 55 pS and 84 pS channels showed flickering and were active for less than 2 min after excising the patch. The 111 pS channel was an outward rectifier, and the open state probability (po) decreased in the inside-out configuration when the Ca2+ concentration was raised from pCa 7 to pCa 3. The 122 pS channel also showed outward rectification. This type of channel was activated after changing from the cell-attached to the inside-out configuration and it did not inactivate during more than 30 min. The po was Ca2+- and voltage-insensitive. One hundred micron glibenclamide reversibly reduced po. The 132 pS channel was an outward rectifier and was Ca2+-insensitive. The 149 pS channel inactivated in the inside-out configuration. The 149- and the 223 pS channel showed inward rectification. The 111 pS channel had similar properties to the Ca2+-dependent K+ channel and the 122 pS channel resembled the ATP-inhibited K+ channel found previously in Retzius neurons of the adult leech.

Adenosine Triphosphate↗