Biomedical subjects

J Vachtenheim

Publications and source records attributed to J Vachtenheim.

At least 19 recordsLinked to original sources

PubMed2006

Distinct co-regulation of endogenous versus transfected MITF-dependent tyrosinase promoter.

The tissue-specific control of gene activation in melanocytes is directed by the microphthalmia-associated transcription factor (MITF), a master regulator of melanocyte development and differentiation. Tyrosinase is a rate-limiting enzyme in melanin biosynthesis and a prototypic MITF target. While the expression of tyrosinase is restricted to pigmented cells, the transfected tyrosinase promoter is active in a broad range of cell types if ectopic MITF is co-expressed. Here we used the E1A oncoprotein and its mutants as repressors of both the transiently transfected and endogenous tyrosinase promoter. We report that the requirement of the E1A N-terminus for repression of the MITF-activated tyrosinase promoter and the sensitivity to derepression by the histone deacetylase inhibitor trichostatin A are distinct when the activity of the transiently transfected or the endogenous promoter is analysed in U2-OS cells. Thus, for transiently transfected versus chromatin-embedded promoter, the activity of obligatory MITF seems to be executed through different mechanisms of transcriptional coactivation.

Cell Line, Tumor↗

PubMed2005

Low mutational rate of K-ras codon 12 in singular bronchoscopy specimens in suspected lung cancer.

Mutations of the K-ras gene are found in a subset of non-small- cell lung carcinomas (NSCLC). The aim of our study was to determine the K-ras codon 12 mutation in the first, singular bronchoscopy specimen in parallel with the cytological examination for the diagnosis of lung cancer. Samples were obtained by diagnostic bronchoscopy in 140 patients with suspected lung tumors. The analysis of K-ras mutations was carried out by a sensitive two-step mutation- enriched polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. This method has been confirmed earlier to be positive for mutated tumor cells and negative for normal lung parenchyma and bronchus. Of the 140 patients with suspected cancer, 93 were diagnosed as NSCLC by cytology or histology in either the same specimen used for the detection of K-ras mutation or in later biopsies. However, only four K-ras codon 12 mutations were detected in the first bronchoscopic material: one in adenocarcinoma, two in squamous cell tumors, and one mutation was found in a patient with dysplasia which was diagnosed later as a squamous cell carcinoma. Our findings indicate that although the K-ras (codon 12) mutation is a gene lesion infrequently detectable in a singular specimen taken at the first bronchoscopy examination in cases of clinically suspected lung cancer, the detection of this mutation can help to confirm the cytological diagnosis of NSCLC or may be even diagnostic in cytologically negative cases.

Adult↗

PubMed2004

Repression of the melanocyte-specific promoter of the microphthalmia-associated transcription factor by the adenoviral E1A 12S oncoprotein.

Melanocytes express MITF, which is crucial for the development of the melanocyte lineage and is overexpressed in malignant melanomas. Adenoviral E1A protein-expressing melanocytes are unpigmented, with the expression of MITF being silenced. We tested here a direct repression of the melanocyte-specific MITF promoter by E1A and its mutants. We found that the extreme N-terminus and conserved region 1 are required for repression. In contrast, the motif in conserved region 2 (a.a. 122-126), as well as amino acids 26-35 at the N-terminus, are not necessary. As these two later motifs mediate E1A binding to the retinoblastoma protein or to the transcriptional co-activator TRRAP, respectively, and are important for transformation by E1A in cooperation with other oncogenes, the results suggest that the transformation-defective E1A can still efficiently repress the MITF promoter. The CREB binding motif-mutated promoter had lower activity, but was also repressed by the same E1A mutants in human melanoma cells. The E1A protein is known to also exert an antitumour activity, which is associated with its transcription repression function and the ability to induce apoptosis, and is a potential antimelanoma agent. Since recent data suggest that MITF may be a survival factor for melanoma cells, the E1A mutants described here might constitute a good targeting agent for antimelanoma therapy.

Adenovirus E1A Proteins↗

PubMed2004

Microphthalmia transcription factor: a specific marker for malignant melanoma.

The transcription factor microphthalmia (MITF) is required for the formation of normal melanocytes during embryonic development and for the expression of pigment cell-specific markers, which are the downstream transcriptional targets of MITF. It also seems to be crucial for the survival of malignant melanocytes. The special interest of this review is the possible utility of MITF as a marker of malignant melanoma. Melanocyte-specific isoform of MITF appears to be a unique molecule in the differential diagnosis of melanocytic tumors.

Biomarkers, Tumor↗

PubMed2002

[Complete atrioventricular block (with Adams-Stokes syndrome) in systemic connective tissue disease. Electrocardiographic development in three patients].

The association of high grade atrioventricular heart block with systemic connective tissue diseases is very rare. To date, only sporadic case reports or reviews appeared in the literature. Three cases of such association observed by the author are described here. The patients were a 51 years old man with systemic sclerosis and two women, a 64 years old patient with visceral nodous seropositive rheumatoid arthritis, and second was a 74 years old patient with systemic lupus erythematosus, the oldest of the group of patients with this disease. In two of the three patients, Adams-Stokes attack was a cause of death. The author did not observe this high grade atrioventricular block in patients with systemic connective tissue diseases the last 32 years. First and second grade heart blocks were, however, o chi asionally seen and responded well to the treatment of the systemic disease. Thus, in patients with systemic connective tissue diseases and emergency symptoms, it is recommended to consider also this rare association. While, two decades ago, patients frequently died after the Adams-Stokes attack, the treatment of the high grade block is now successful due the permanent cardiostimulator. In the last years, there are almost no reports about the association of systemic connective tissue diseases with high grade heart block, presumably because of the efficient new treatment approached to systemic diseases including modern immunomodulation drugs.

Adams-Stokes Syndrome↗

PubMed2001

Transcriptional repression of the microphthalmia gene in melanoma cells correlates with the unresponsiveness of target genes to ectopic microphthalmia-associated transcription factor.

In the melanocyte, expression of genes required for pigment formation is mediated by the microphthalmia transcription factor, which is also critical for the development and survival of normal melanocytes during embryogenesis. Here we show that the expression of the melanocyte-specific isoform of microphthalmia transcription factor is lost in a subset of human melanoma cell lines, accompanied by the repression of tyrosinase and tyrosinase-related proteins 1 and 2, the three transcriptional target genes for microphthalmia. After the forced expression of microphthalmia transcription factor in melanoma cells where the expression of endogenous microphthalmia gene was found to be extinguished, no restoration of the melanogenic phenotype occurred and the transcription of the three microphthalmia transcription factor target genes remained silent. The transcription activation domain of microphthalmia transcription factor, tested as a GAL-MITF fusion protein, remained fully functional in these cells, however, and ectopic microphthalmia transcription factor localized normally to the nucleus and bound to the tyrosinase initiator E-box in gel retardation assays. Thus, the block of differentiation in microphthalmia-transcription-factor-negative melanomas extended the transcriptional repression of the microphthalmia transcription factor gene alone, and endogenous promoters in these melanoma cells became no longer responsive to microphthalmia transcription factor when this was substituted exogenously. The data presented suggest that a specific nuclear context is required for the transcriptional activation of the melanocyte markers by the microphthalmia transcription factor in malignant melanocytes and this specificity is lost concomitantly with the transcriptional repression of microphthalmia transcription factor.

Cell Division↗

PubMed1999

Expression of genes for microphthalmia isoforms, Pax3 and MSG1, in human melanomas.

Microphthalmia (MITF) gene product, a transcription factor of the basic-helix-loop-helix type, is thought to play a role in the regulation of genes encoding the enzymes necessary for melanogenesis. These include tyrosinase, TRP-1 and TRP-2. Melanocyte-specific isoform of microphthalmia, MITF-M, is expressed in normal and malignant melanocytes. The presence of two other isoforms of microphthalmia, MITF-A and MITF-H, which differ from MITF-M in the amino-terminus, was demonstrated also in some non-melanocytic lineages. Here we have analyzed the presence of all three known isoforms of MITF mRNA in a panel of 17 human melanoma cell lines by a reverse transcriptase-polymerase chain reaction using isoform-specific primers. While, as expected, the predominant form in melanoma cell lines was MITF-M, low amounts of MITF-A mRNA was found in almost all melanomas, as well as in most of 20 tumor cell lines of the non-melanocyte origin (lung and colon carcinomas, osteosarcomas and neuroblastomas). The expression of MITF-H was not detected, with a few exceptions, in the tested cell lines. Pax3 transcription factor was reported earlier to regulate positively the melanocyte-specific promoter of the MITF gene. We found here that the Pax 3 mRNA was expressed in all melanoma cell lines, even in those that had repressed the MITF-M and were amelanotic. This suggests that additional factors, besides Pax3, are required for the MITF expression. The MSG1 (melanocyte-specific gene 1), a gene originally isolated from melanocytes and containing a strong transcription activation domain, was also found expressed in all melanomas and most non-melanocyte tumor cell lines. Together, these data indicate that the MITF-M isoform is the major type of MITF mRNA present in human melanoma cell lines and show that the expression of the isoform MITF-A and the MSG1 is not restricted to malignant melanocytes and occurs in a wide range of tumor cell lines.

DNA-Binding Proteins↗

PubMed1997

Expression of the aromatic L-amino acid decarboxylase mRNA in human tumour cell lines of neuroendocrine and neuroectodermal origin.

Neuroendocrine differentiation of lung tumours is characterised by the expression of several neuroendocrine markers and is confined mostly to specific histological subtypes, i.e. small cell carcinomas and carcinoids. One of the markers seen in neuroendocrine tumours, high activity of the aromatic L-amino acid decarboxylase (AADC), is helpful in distinguishing the classic and variant small cell lung tumour subtypes. Here, we have analysed the expression and quantified the level of mRNA coding for AADC in human tumour cell lines by use of the reverse transcription and polymerase chain reaction (RT-PCR). High amounts of mRNA were detected in classic small cell lung carcinomas and a neuroblastoma cell line. Other cell lines (melanomas, non-small cell lung carcinomas and osteosarcoma) also showed AADC expression, but the levels were 2-3 orders lower. Also, the tissue-specific (neuronal versus liver-specific) mRNA type has been estimated. Small cell lung carcinomas, neuroblastoma and melanoma expressed messenger RNA specific for neuronal tissues. Importantly, the non-small cell lung carcinoma cell lines expressed either liver-specific (non-neuronal) mRNA (cell line A549) or predominantly the neuronal (cell line NCI-H520) AADC message. These data indicate that a range of tumour cell lines transcribe the AADC gene and that two distinct types of AADC mRNA which reflect the embryonal (neuronal or non-neuronal) origin of the tumour may be produced in non-small cell lung cancer cells.

Adenocarcinoma↗

PubMed1997

Occurrence of ras mutations in human lung cancer. Minireview.

Members of ras family of oncogenes, when activated by a point mutation, have been implicated in many types of human cancers. In several types of human solid tumors, point mutations of the K-ras gene are relatively frequent. Among lung cancers, a subset of non-small cell lung carcinomas, mostly adenocarcinomas, contains activated K-ras. The examination of K-ras mutations in samples obtained for diagnostic reasons, such as bronchial biopsies or bronchoalveolar lavage fluid, may be used as a supplement in the early diagnosis of lung adenocarcinoma.

Carcinoma, Non-Small-Cell Lung↗

PubMed1996

Melanogenic factors: regulation of gene expression.

Melanogenesis is a multistep biochemical process resulting in the formation of melanin in pigment cells in the skin and the eye. Three melanogenic factors, tyrosinase, TRP1, and TRP2 participate in the pathway. Here, the regulation of gene expression of these melanocyte-specific markers is shortly reviewed.

Animals↗

PubMed1995

The Microphthalmia gene product interacts with the retinoblastoma protein in vitro and is a target for deregulation of melanocyte-specific transcription.

Little is known of the molecular mechanisms underlying the differentiation of the melanocyte from the melanoblast or the progression from the melanocyte to a malignant melanoma. Since the adenovirus E1A products have proved a useful tool for understanding control of differentiation in other systems, we explored the possibility of using E1A as a probe for factors controlling melanocyte-specific gene expression and differentiation. The results obtained show that the adenovirus E1A 13S, but not the 12S, product can transform the highly pigmented and TPA-dependent melanocyte cell line melan-a. Transformation is characterised by a morphological change, loss of TPA-dependence, the ability to grow in soft agar and strikingly, loss of pigmentation which correlates with loss of expression of the melanocyte-specific TRP-1 and tyrosinase genes. Cotransfection assays demonstrated that repression of TRP-1 by E1A correlated with E1A binding to p105Rb and p300, with the target in the TRP-1 promoter being the M-box, and 11 bp basic-Helix-loop-Helix (bHLH) factor-binding motif conserved between melanocyte-specific promoters. Consistent with the M-box acting as a target for E1a-mediated transcription repression, we also show that the basic-helix-loop-helix-leucine zipper (bHLH-LZ) protein (Mi) encoded by the microphthalmia gene (mi), which is required for pigment cell differentiation, is a positive acting transcription factor which can interact with the retinoblastoma product in vitro and activate the TRP-1 promoter. Moreover, expression of the mi gene was reduced around 50-fold in the non-pigmented E1a-transformed melan-a cells compared to the nontransformed melan-a cell line, with ectopic expression of Mi able to prevent repression of the tyrosinase and TRP-1 promoters in the presence of E1A. Mi therefore appears to play a crucial role in melanocyte-specific gene expression. The parallels between repression of myogenesis and muscle cell bHLH factors, and Mi and melanocyte differentiation are discussed.

Adenovirus E1A Proteins↗

PubMed1995

[Non-steroidal antirheumatic ointments in the treatment of primary periarticular and intramuscular fibrositis].

The author presents his experience assembled in a short-term (two-week) therapeutic trial with Mobilisin ointment, which contains flufenamic acid, in 50 patients with primary localized periarticular and muscular fibrositis. The preparation was used locally three times per day-2-3 cm of ointment pressed from a tube. The patients were given a form in which they recorded every night the effect classified in four grades from the best to zero effect. In 49 the tolerance of the ointment was very good. In 45 patients a therapeutic effect was achieved (90%), comprising 21 (42%) where the effect was excellent, in 24 it was good or satisfactory (48%) and only in 5 patients no effect was recorded or the patents' statement was vague. In the first group of 21 patients 16 were able to abandon analgetic and anti-inflammatory treatment with non-steroid antirheumatics. Patients with the muscular form of fibrositis practically agreed in favour of the ointment. Gels according to these patients tissues. The authors remind that according to their experience gels, incl. Mobilisin, are suited for periarticular forms of fibrositis. It is also useful to rub the ointment in micro-massage to achieve a greater initial hyperaemia and better resorption. Mobilisin ointment may prove useful also in other disciplines, in particular orthopaedics, surgery, traumatology, neurology, rehabilitation and sports medicine.

Adult↗

PubMed1995

Mutations of K-ras oncogene and absence of H-ras mutations in squamous cell carcinomas of the lung.

Mutations of the K-ras gene have been implicated in the pathogenesis of human lung adenocarcinomas. In most studies published so far, squamous cell lung cancers harbored ras mutations only exceptionally or no mutations were detected at all. We have examined 141 lung tumor DNA samples for mutations in codons 12, 13, and 61 of K-ras and H-ras oncogenes. A large panel of 118 squamous cell carcinomas was included in the study. For K-ras codon 12, we used a sensitive two-step PCR-restriction fragment length polymorphism method which detects <1% of mutated DNA in the sample. K-ras mutations were found in 17 tumors (12%; 14 in codon 12 and 3 in codon 13). Among 19 adenocarcinomas, mutation was revealed in 7 samples (37%). Of these, one sample harbored two point mutations in codon 12. Nine mutational events were found in squamous cell carcinomas (8%, one adenosquamous carcinoma included, all in codon 12). Of four large cell carcinomas, one contained a mutation. Mutant-enriched PCR products harboring mutations were directly sequenced. Fifteen mutational events were G-->T transversions or G-->A transitions, one was a G-->C transition, and one sample revealed a frameshift deletion of one G from codon 12. Similar mutational spectrum was found in both squamous cell carcinomas and adenocarcinomas, suggesting similar carcinogenic pathways in both histological types of the tumor. The presence of mutations did not correlate with the stage of the disease. Moreover, we analyzed all samples for mutations in codons 12, 13, and 61 of the H-ras gene. We found only one mutation in codon 12. Thus, H-ras mutations apparently play an inferior role in lung carcinogenesis. We conclude that mutations of the K-ras oncogene can play a role in the development of not only lung adenocarcinomas but also of a subset (about 8%) of squamous cell carcinomas.

Adenocarcinoma↗

PubMed1994

Hypomethylation of CCGG sites in the 3' region of H-ras protooncogene is frequent and is associated with H-ras allele loss in non-small cell lung cancer.

The methylation of MspI/HpaII sites flanking a variable tandem repeat in the 3' region of the c-Ha-ras protooncogene was analyzed in 74 DNA samples of non-small cell lung carcinomas and control lung tissues. Of 39 informative samples, 7 allelic deletions (18%) were found at the c-Ha-ras locus and of these, five (71%) showed hypomethylation of the nondeleted allele. Heterozygous DNA samples without allele loss revealed hypomethylation in 37% (12 of 32). Among 35 homozygotes, 9 showed hypomethylation (26%). We also analyzed c-Ha-ras mutations at codons 12, 13, and 61 by polymerase chain reaction and designed restriction fragment length polymorphism and found no mutation. Thus, c-Ha-ras mutations are not associated with the development of the detected abnormalities. We conclude that hypomethylation at specific sites in the 3' region is associated with loss of heterozygosity for the c-Ha-ras gene in non-small cell lung cancer. The finding that, in informative samples, hypomethylation occurs 2-3 times more frequently than allelic loss suggests that it might be a change contributing or predisposing to a genetic instability that can ultimately lead to c-Ha-ras allelic deletions found in tumor DNA.

Alleles↗

PubMed1993

TRP-1 expression correlates with eumelanogenesis in human pigment cells in culture.

We have investigated the relationship in human cultured normal and malignant melanocytes between the accumulation of mRNAs encoding tyrosinase and tyrosinase-related protein-1 (TRP-1), the activity of tyrosinase and the presence of melanin. Tyrosinase mRNA correlates with tyrosinase activity and with the presence of pheomelanin, eumelanin or both melanin types. In contrast TRP-1 mRNA is only detectable in cells containing eumelanin, which suggests a role for TRP-1 in the eumelanin synthesis pathway.

Base Sequence↗

PubMed1993

[The locomotor system in irreversible renal failure treated with regular dialysis].

Changes of the locomotor apparatus in prolonged uraemia with regular dialyzation treatment determine the quality of life with all its consequences for the patient. The greatest impact on osteodystrophic disease (the most typical finding on the skeleton) is exerted by the length of dialyzation treatment. Of 216 patients having regular dialyzation treatment in 1979 to 1992 the authors observed osteodystrophic disease in 25, i.e. 11.6%. As to other most frequently observed changes they recorded osteoporosis in 12.9%, only very rarely osteomalacia and even osteopetrosis (1.8%). Carpal tunnel syndrome was recorded in 17.4% as a symptom of so-called dialyzation amyloidosis and in one man they observed the development of typical rheumatoid arthritis shortly after the onset of haemodialyzation. This is a rare observation not described in the literature so far. Crystalline arthropathy, incl. typical attacks of gout, were recorded only in 11 patients (5%). Changes on the locomotor apparatus in conjunction with irreversible renal failure with regular dialyzation treatment were recorded in 45%. It is important to differentiate findings which are not associated with uraemia and haemodialysis. This applies in particular to osteoarthritis deformans of the joints and spine. In major uraemic changes participates in particular secondary hyperparathyroidism. These changes comprise in particular osteolysis or even spontaneous absorption, erosive changes and destructive spondylopathy. Contemporary findings on the locomotor apparatus are so varied that they must be classified.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Diseases, Metabolic↗

PubMed1992

[Oxalosis in patients on regular dialysis therapy].

The authors draw attention to the case of a 46-year-old man who developed after three years of regular dialyzation treatment three times a week the first manifestations of acquired generalized oxalosis. The oxalosis was most marked on the skin, skeleton, heart, and kidneys. Oxalosis was confirmed after eight years of dialysis after death by post-mortem and histological examination and microscopic detection of oxalate crystals. The authors recommend that as part of regular dialyzation treatment patients should not be given more than 100 mg ascorbic acid per day. Oxalates are also the end product of degradation of ascorbic acid and high doses may lead also to hyperoxalosis. Moreover deposits in some visceral organs, in particular the heart may cause clinical manifestations. In the authors patients they caused attacks of auricular flutter. Although these clinical manifestations develop only rarely, the latent form of acquired oxalosis is probably more frequent.

Bone Diseases↗

PubMed1992

[Feldene in local therapy of deforming gonarthroses].

The author submits the results of Feldene gel therapy which contains 5 mg piroxicam per 1 g. The preparation was applied to patients with deforming gonarthrosis, always on one joint three times per day for two weeks. The evaluation was made before the unset of treatment and on the 7th and 14th day. It was an open clinical therapeutic trial. In 97.5% the tolerance was excellent. Undesirable manifestations developed only in one female patients who had sensations of irritation which disappeared in three days and interruption of treatment was not necessary. The authors evaluated pain, mobility, required assistance during change of position-sitting and standing up and when climbing stairs. The evaluation was made by the physician and the patient. Significant results were achieved in particular as regards pain but also in the other parameters. In more than 90% regression of all evaluated criteria was recorded. The preparation is evaluated very favourably. It helps not only in treatment proper but has also a comprehensive effect. Feldene gel is an important asset to local treatment in rheumatology and will be most probably valuable also in orthopaedics, surgery and sports medicine.

Administration, Topical↗