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Biomedical subjects

M Fritsch

Publications and source records attributed to M Fritsch.

At least 73 records · Page 4Linked to original sources
PubMed2001

Nasopharyngeal extension of a craniopharyngioma in a 4 year old girl.

Nasopharyngeal extension of a craniopharyngioma is very rare and usually presents with headache, nasal obstruction and visual disturbances. We present a case of a 4 year old girl, who became symptomatic with visual deterioration. MRI showed a huge supra - and infrasellar cystic craniopharyngioma with extension into the sphenoid sinus. Primary treatment was a transnasal puncture of the cyst followed by a subfrontal approach with removal of the tumour preserving the chiasm and optic nerves. The visual acuity postoperatively improved while she needed hormone replacement due to panhypopituitarism. Follow-up 12 months after the operation showed no recurrence. This is the youngest patient of about 27 patients reported so far in the literature.

Brain Neoplasms↗
PubMed2001

Sebocytes are the key regulators of androgen homeostasis in human skin.

The mRNA expression patterns of the androgen receptor and the androgen metabolizing enzymes 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase, 17beta-hydroxysteroid dehydrogenase, 5alpha-reductase, and 3alpha-hydroxysteroid dehydrogenase were investigated in three different cell populations originating from human skin, SZ95 sebocytes, HaCaT keratinocytes, and MeWo melanoma cells, by means of reverse transcription polymerase chain reaction. Restriction analysis of cDNA fragments was performed to identify isozymes of 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase and 3alpha-hydroxysteroid dehydrogenase. In addition, 3H-dihydroepiandrosterone and 3H-testosterone were used as substrates to determine the metabolic activity of these enzymes in SZ95 sebocytes, primary sebocyte cultures, and HaCaT keratinocytes. Furthermore, the effects of the selective 5alpha-reductase type 1 and 2 inhibitors, 4,7beta-dimethyl-4-aza-5alpha-cholestan-3-one and dihydrofinasteride, respectively, and of the 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase inhibitor cyproterone acetate on androgen metabolism were investigated. Androgen receptor mRNA was detected in SZ95 sebocytes and HaCaT keratinocytes but not in MeWo melanoma cells, whereas 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase isotype 1 mRNA and metabolic activity were only found in SZ95 sebocytes. The enzyme activity could be inhibited by cyproterone acetate. Type 2 17beta-hydroxysteroid dehydrogenase, type 1 5alpha-reductase, and 3alpha-hydroxysteroid dehydrogenase mRNA were expressed in all three cell populations tested, whereas type 3 17beta-hydroxysteroid dehydrogenase mRNA could only be detected in SZ95 sebocytes. The major metabolic steps of testosterone in SZ95 sebocytes, primary sebocyte cultures, and HaCaT keratinocytes were its conversion to androstenedione by 17beta-hydroxysteroid dehydrogenase and further to 5alpha-androstanedione by 5alpha-reductase. The type 1 5alpha-reductase selective inhibitor 4,7beta-dimethyl-4-aza-5alpha-cholestan-3-one, but not the type 2 selective inhibitor dihydrofinasteride, inhibited 5alpha-reductase at low concentrations in SZ95 sebocytes and HaCaT keratinocytes. 5alpha-androstanedione was degraded to androsterone by 3alpha-hydroxysteroid dehydrogenase, which exhibited a stronger activity in HaCaT keratinocytes than in SZ95 sebocytes and in primary sebocyte cultures. Lower levels of 5alpha-dihydrotestosterone and 5alpha-androstanediol were also detected in all cells tested. Our investigations show that specific enzyme expression and activity in cultured sebocytes and keratinocytes seem to allocate different duties to these cells in vitro. Sebocytes are able to synthesize testosterone from adrenal precursors and to inactivate it in order to maintain androgen homeostasis, whereas keratinocytes are responsible for androgen degradation.

Androgens↗
PubMed2000

Molecularly confirmed primary prostatic synovial sarcoma.

We report the second molecularly-confirmed primary prostatic synovial sarcoma. The diagnosis was particularly elusive at the light microscopic level in that the tumor failed to show epithelial differentiation, but it did show combined spindle-cell and poorly differentiated (round-cell) morphologies. The immunohistochemical staining profile was nonspecific and potentially misleading. Only by demonstration of the characteristic SYT-SSX gene fusion of synovial sarcoma by reverse transcriptase polymerase chain reaction (RT-PCR) analysis of RNA extracted from archival material could the diagnosis be confirmed. This case further illustrates the use of this technique in diagnostic pathology.

Adult↗
PubMed2000

Detection of the ETV6-NTRK3 chimeric RNA of infantile fibrosarcoma/cellular congenital mesoblastic nephroma in paraffin-embedded tissue: application to challenging pediatric renal stromal tumors.

We report the development of a reverse transcriptase polymerase chain reaction assay that reliably detects the ETV6-NTRK3 chimeric RNA characteristic of infantile fibrosarcoma and the cellular variant of congenital mesoblastic nephroma (CMN) in formalin-fixed, paraffin-embedded tissue blocks. The 188 base pair polymerase chain reaction fusion product was detected in 11 of 12 cases of cellular CMN from which a larger sized control RNA band could be amplified, and even in 7 of 8 cases in which the control band was not detectable. A variety of other tumors that are in the histologic differential diagnosis of cellular CMN yielded negative results, including four classic CMNs, four rhabdoid tumors of the kidney, and four clear cell sarcomas of the kidney, confirming the assay's specificity. We further demonstrate the assay's utility by illustrating two cases of molecularly confirmed cellular CMN that mimicked rhabdoid tumor and clear cell sarcoma of the kidney. In contrast to previous reports, five mixed CMNs that had both classic and cellular areas all lacked the ETV6-NTRK3 fusion transcript. These results suggest that cases morphologically defined as mixed CMN may represent a mixed group of genetically distinct entities.

Artificial Gene Fusion↗
PubMed1999

Identification of a unique liganded estrogen receptor complex released from the nucleus by decavanadate.

Unoccupied estrogen receptor (ER) can be extracted from tissues by homogenization with a hypotonic buffer, whereas hormone-occupied ER becomes tightly bound to the nuclear pellet and must be extracted with high-salt-containing buffers. The molecular basis for estrogen-induced tight nuclear binding of ER remains an important puzzle. The different subcellular fractionation behaviors of the occupied and unoccupied ER are presumed to be due to a difference in their ability to interact with nuclear components, such as DNA and proteins. The proteins that are the targets for interaction with the hormone-occupied ER may be important for transcriptional regulation. However, the salt-extracted ER is recovered as a homodimer, and associated proteins are presumably lost due to the high-salt conditions. We have discovered an alternate method of releasing the occupied ER from the nucleus. Inclusion of 2 mM orthovanadate, polymerized primarily to decavanadate, in a hypotonic buffer efficiently releases over 90% of estrogen-bound ER from the nuclear pellet. The recovered ER complex is fully functional in terms of estrogen and DNA binding and is full-length by western blot analysis. Our data suggest that the mechanism of ER release is by decavanadate competition with nuclear DNA, rather than by inhibition of a phosphotyrosine phosphatase. Of particular interest, the decavanadate released occupied ER complex shows distinct behavior by sucrose density gradient sedimentation analysis. It is larger than the salt-extracted transformed ER, suggesting that an occupied ER in complex with nuclear proteins may be released from the nucleus by decavanadate.

Animals↗
PubMed1999

Lymphoproliferative disorder of fetal origin presenting as oligohydramnios.

Lymphoma involving the placenta or fetus remains a very rare event. All cases reported to date have shown the lymphoma cells to be of maternal origin in that the tumor cells have preferentially involved the intervillous spaces with sparing of the villi and fetal circulation. We report a novel case of a monoclonal primary placental Epstein-Barr virus (EBV)-associated B-cell lymphoma of fetal origin. The placenta of a 20-week stillborn fetus born to a 19-year-old gravida 1 para 0 woman, presenting with oligohydramnios, showed a large cell infiltrate confined within villi and sparing the intervillous spaces, indicative of preferential involvement of the fetal circulation. Necropsy did not show any other site of involvement by malignant lymphoma or other abnormalities. Immunophenotypic studies showed the tumor cells to be of B-cell phenotype with a relatively high proliferation rate. EBV EBER1 RNA was identified in more than 95% of tumor cells, and polymerase chain reaction studies showed EBV EBNA1 strain type A and wildtype EBV LMP1. Analysis of the immunoglobulin heavy chain by polymerase chain reaction showed a monoclonal B-cell population. In situ hybridization studies using a commercially available probe directed at repeated sequences on the human Y chromosome showed a single intense signal within trophoblastic epithelium and lymphoma cells, indicative of male origin. The mother remains in good health 11 months after delivery.

Diagnosis, Differential↗
PubMed1999

Phosphorylation of Drosophila heat shock transcription factor.

The role that phosphorylation plays in regulating heat shock factor (HSF) function and activity has been the subject of several studies. Here, we demonstrate that Drosophila melanogaster HSF (DmHSF) is a phosphoprotein that is multiply phosphorylated at some sites and is dephosphorylated at others upon heat shock. However, the steady-state level of phosphorylation of Drosophila HSF remains unchanged after heat shock. Phosphoamino-acid analysis reveals that predominantly serine residues are phosphorylated for both the non-shocked and heat shocked molecules. Gel mobility shift assays using extracts from SL2 cells treated with a variety of phosphatase and kinase inhibitors show little or no effect on the heat shock induced DNA binding activity of HSF or on its recovery. We conclude that phosphorylation plays no significant role in regulating the heat induced DNA binding activity of Drosophila HSF.

Animals↗
PubMed1998

A TCR alpha chain transgene induces maturation of CD4- CD8- alpha beta+ T cells from gamma delta T cell precursors.

The proportion of CD4- CD8- double-negative (DN) alpha beta T cells is increased both in the thymus and in peripheral lymphoid organs of TCR alpha chain-transgenic mice. In this report we have characterized this T cell population to elucidate its relationship to alpha beta and gamma delta T cells. We show that the transgenic DN cells are phenotypically similar to gamma delta T cells but distinct from DN NK T cells. The precursors of DN cells have neither rearranged endogenous TCR alpha genes nor been negatively selected by the MIsa antigen, suggesting that they originate from a differentiation stage before the onset of TCR alpha chain rearrangements and CD4/CD8 gene expression. Neither in-frame V delta D delta J delta nor V gamma J gamma rearrangements are over-represented in this population. However, since peripheral gamma delta T cells with functional TCR beta gene rearrangements have been depleted in the transgenics, we propose that the transgenic DN population, at least partially, originates from the precursors of those cells. The present data lend support to the view that maturation signals to gamma delta lineage-committed precursors can be delivered via TCR alpha beta heterodimers.

Animals↗
PubMed1998

Gammadelta T-cell precursor-derived CD4- CD8- alphabeta T cells retain gammadelta cell function.

We have previously shown that some of the DN alphabeta+ T cells arising in TcR alpha-chain transgenic mice are of gammadelta T cell origin, based on phenotypic data and on their status of TcR gene rearrangements. In the present report we investigated the impact of alphabeta TcR expression on the functional programme of the mature gammadelta precursor-derived DN alphabeta+ T cells. Our results demonstrate that both their proliferative capacity and their cytokine production profile are similar to that of gammadelta T cells. Furthermore, both transgenic DN alphabeta+ T cells and DN gammadelta+ T cells up-regulate CD8alpha expression after activation, but, in contrast to CD4+ alphabeta T cells, are unable to induce proliferation of naive B cells. Thus, our results suggest that the effector functions of mature T cells are determined independently of the TcR isotype, probably at an early stage of differentiation, and thereby have important implications for current models of T-cell lineage commitment.

Animals↗
PubMed1998

Evidence of heterogeneity and quantitative differences of the type 1 5alpha-reductase expression in cultured human skin cells--evidence of its presence in melanocytes.

Steroid 5alpha-reductase is of crucial importance in androgen physiology because it catalyzes the conversion of testosterone into the more potent 5alpha-dihydrotestosterone in androgen-regulated target tissues. The enzyme occurs in two isoforms, whereby type 1 isozyme exists mainly in the skin and type 2 in the prostate. By using human cell cultures, we examined cutaneous expression and subcellular localization of type 1 5alpha-reductase in vitro. In immunocytochemistry, type 1 5alpha-reductase was detected in the cytoplasm of cultured human sebocytes, keratinocytes, fibroblasts, dermal microvascular endothelial cells, hair dermal papilla cells, and melanocytes. In western blot studies, two closely lying bands of 21-27 kDa were detected, possibly indicating heterogeneity of the type 1 5alpha-reductase in all the cell types tested, with the exception of beard dermal papilla cells. Northern blot studies revealed most abundant type 1 mRNA in neonatal foreskin keratinocytes, followed by adult facial sebocytes. Occipital hair dermal papilla cells presented higher levels of type 1 5alpha-reductase mRNA than those of beard. These findings were confirmed by semiquantitative reverse transcriptase polymerase chain reaction coupled with high performance liquid chromatography analysis. Taken together, it seems likely that in cultured human skin cells there exist (i) heterogeneity of type 1 5alpha-reductase protein and (ii) quantitative differences in its transcriptional and translational expression levels.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1998

The human sebocyte culture model provides new insights into development and management of seborrhoea and acne.

Seborrhoea and acne are exclusively human diseases and sebaceous gland differentiation is species specific. Therefore, fundamental research on human sebaceous cell function and control requires human in vitro models. The human sebocyte culture model, introduced in 1989, has been used in several studies to elucidate sebaceous gland activity and its regulation at the cellular level. Cultured human sebocytes have been shown to preserve important sebocytic characteristics, although they undergo an incomplete terminal differentiation in vitro. In vitro synthesis of free fatty acids without bacterial involvement and marked interleukin 1 alpha expression at the mRNA and protein levels with no further induction by lipopolysaccharides lead to the assumption that human sebocytes may initiate acne lesions by an intrinsic mechanism. Androgens affected sebocyte activity in vitro in a manner dependent on the localization of the sebaceous glands. In vitro stimulation of sebocyte proliferation by androgens could be completely abolished by spironolactone. Cultured sebocytes strongly expressed type 1 5 alpha-reductase and metabolized testosterone to androstenedione, 5 alpha-androstanedione, 5 alpha-dihydrotestosterone, androsterone and 5 alpha-androstanediol, whereas the levels of 5 alpha-reductase activity were probably not feedback regulated. 4,7 beta-Dimethyl-4-aza-5 alpha-cholestan-3-one, a type 1 5 alpha-reductase inhibitor, induced an early, marked down-regulation of 5 alpha-reductase activity in human sebocytes in vitro, while hydrofinasteride, a type 2 inhibitor, required 10(3)-fold higher concentrations to induce similar effects. Stimulation of sebocyte proliferation by insulin, thyroid-stimulating hormone and hydrocortisone indicates that the hormonal control of the sebaceous gland could be a complex mechanism. Retinoids inhibited sebocyte proliferation in a dose-dependent manner and down-regulated lipid synthesis and sebocyte differentiation in vitro. Isotretinoin was the most potent compound. On the other hand, vitamin A was found essential for sebocyte activity and differentiation in vitro and could be partially substituted by synthetic retinoids. The inhibitory effect of isotretinoin on sebocyte proliferation was barely affected by the presence of vitamin A. The low persistent isotretinoin levels or, more likely, the considerably elevated tretinoin concentrations detected in human sebocytes after treatment with isotretinoin in vitro may be responsible for the inhibitory effect of this compound on sebocyte activity.

Acne Vulgaris↗
PubMed1997

Two populations of the estrogen receptor separated and characterized using aqueous two-phase partitioning.

Two populations of the rat uterine estrogen receptor (ER) were separated and characterized using aqueous two-phase partitioning. Countercurrent distribution of rat uterine cytosolic ER allowed rapid and efficient separation of two populations, one population partitioned preferentially into the top phase (T, K(obs) = 3-6) and the other into the bottom phase (B, K(obs) = 0.01-0.03). The majority of unoccupied cytosolic ER is in the T population. Upon estrogen binding and/or heating to 30 degrees C in vitro the T population is converted to the B population. The transition from T to B does not exclusively involve loss of heat shock protein 90 and does not alter the ligand binding ability of the steroid binding domain. Using the human ER steroid binding domain overproduced in Escherichia coli and the steroid binding domain generated by partial trypsinization of the rat uterine ER, we demonstrate that the characteristic distinguishing T and B populations is not localized to this domain alone but may be associated with the amino terminal half of the ER (the A/B and DNA binding domains). The T to B transition of the ER also occurs in human MCF-7 breast cancer cells upon treatment with estrogen at 37 degrees C.

Animals↗
PubMed1997

Cloning and characterization of a 77-kDa oestrogen receptor isolated from a human breast cancer cell line.

We have cloned and characterized a 77-kDa oestrogen receptor (ER) from an oestrogen-independent subclone of the MCF-7 human breast cancer cell line. This receptor contains an in-frame, tandem duplication of exons 6 and 7, located in the steroid-binding domain of the ER. This mutation has abrogated ligand binding, but not DNA binding, in this mutant ER. We previously described the partial structure of a unique oestrogen receptor (ER) that is expressed in an oestrogen-independent MCF-7:2A subclone of the breast cancer cell line MCF-7 (Pink JJ, Wu SQ, Wolf DM, Bilimoria MM, Jordan VC 1996a, Nucleic Acids Res 24 962-969). Sequence analyses determined the molecular weight of this 80-kDa ER to be 77 kDa, and hereafter this protein will be designated as ER77. Examination of the entire coding sequence of the ER77 mRNA indicates that it contains a tandem duplication of exons 6 and 7. Using a coupled transcription/translation system, a 77-kDa ER, which corresponds to the protein observed in the MCF-7:2A cells, was expressed. The ER77 protein does not bind the ligands [3H] oestradiol or [3H]tamoxifen aziridine. In DNA binding gel shift assays, the in vitro synthesized ER77 binds to a consensus vitellogenin A2 oestrogen-response element. In transient transfection experiments, the mutant ER, alone or in combination with the wild-type ER, does not induce expression of an oestrogen-responsive luciferase reporter construct. In fact, expression of the ER77 in the ER-positive T47D:A18 cell line inhibits E2-induced luciferase expression. Overexpression of wild-type ER in T47D:A18 cells leads to elevated constitutive expression of the luciferase reporter, which was inhibited by co-transfection with ER77. These data suggest that the ER77 can interfere with normal ER activity and does not act as a constitutive activator of oestrogen-independent growth in MCF-7:2A cells. Consequently, the constitutive growth observed in MCF-7:2A cells is probably the result of other ER-mediated pathways.

Amino Acid Sequence↗
PubMed1997

Endoscopic treatment of brain abscess in children.

Three children with intracerebral abscesses were treated endoscopically. Two of the treated abscesses were located in the left temporal lobe and one in the right parietal lobe. The presenting symptoms included headaches, seizures, hemiparesis and signs of infection. Burr hole craniotomy, insertion of a peelaway sheath, obtaining of a specimen, introduction of endoscope, and complete irrigation under view was performed. After this a draining catheter was positioned in the abscess. All three abscesses grew multiple organisms. The patients received longstanding intravenous treatment with antibiotics. The follow-up period in this group ranges between 5 and 32 months. The initial neurological deficits were relieved in all three patients. The follow-up MRI studies revealed minor residual changes without evidence of significant sequelae. Neuroendoscopic treatment of brain abscesses has additional advantages compared to stereotactic aspiration or more complete drainage and lavage.

Brain Abscess↗
PubMed1996

Determination of cytidine 5'-monophospho-N-acetylneuraminic acid pool size in cell culture scale using high-performance anion-exchange chromatography with pulsed amperometric detection.

A simultaneous determination of cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) and its metabolic products, cytidine, CMP and Neu5Ac by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) using a Carbo-Pac PA1 column is described. Preparation of the samples involved a single purification step of the crude cell extract on DEAE-Sepharose. The method is adequate to quantify the amount of CMP-Neu5Ac produced by one culture dish; equivalent to 6.10(6) cells. In addition, a method for desalting and recovery of the separated material was developed to determine the cellular concentration of CMP-Neu5Ac in Madin Darby canine kidney (MDCK) cells. The addition of 5 mM N-acetylmannosamine to the culture medium gave rise to a 6.4-fold elevation of this value.

Animals↗
PubMed1996

Human central neurocytoma cells show neuronal physiological properties in vitro.

Central neurocytoma is a rare brain tumor composed of small round synaptophysin-positive cells, suggesting a neuronal origin of these tumor cells. Glial properties are inferred, however, from the observation that the tumor cells exhibit a strong morphological similarity to oligodendroglioma cells and show an astrocytic differentiation in vitro. To test for neuronal or glial physiological properties, we studied cultured neurocytoma cells derived from a surgical specimen from a 44-year-old man, employing the patch-clamp technique. Early primary cultures were composed of morphologically unique bi- or multipolar cells which were positive for synaptophysin and negative for the astrocyte marker glial fibrillary acidic protein. In the majority of these cells, whole-cell membrane current recordings revealed physiological properties of neurons, i.e., a high density of Na+ currents, the capacity to generate action potentials, and the expression of inotropic neurotransmitter receptors. Metabotropic neurotransmitter receptors could be demonstrated by Ca2+ imaging techniques. The remaining bi- or multipolar cells and almost all cells in later culture stages and in vitro passage lacked these neuronal properties and showed physiological features characteristic of glial cells. We conclude that the major population of neurocytoma cells shows physiological properties of neurons and that with time in culture this population is replaced by electrically passive cells.

Action Potentials↗