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Biomedical subjects

J Mark

Publications and source records attributed to J Mark.

At least 19 recordsLinked to original sources
PubMed1999

Conserved mechanism of PLAG1 activation in salivary gland tumors with and without chromosome 8q12 abnormalities: identification of SII as a new fusion partner gene.

We have previously shown (K. Kas et al, Nat. Genet., 15: 170-174, 1997) that the developmentally regulated zinc finger gene pleomorphic adenoma gene 1 (PLAG1) is the target gene in 8q12 in pleomorphic adenomas of the salivary glands with t(3;8)(p21;q12) translocations. The t(3;8) results in promoter swapping between PLAG1 and the constitutively expressed gene for beta-catenin (CTNNB1), leading to activation of PLAG1 expression and reduced expression of CTNNB1. Here we have studied the expression of PLAG1 by Northern blot analysis in 47 primary benign and malignant human tumors with or without cytogenetic abnormalities of 8q12. Overexpression of PLAG1 was found in 23 tumors (49%). Thirteen of 17 pleomorphic adenomas with a normal karyotype and 5 of 10 with 12q13-15 abnormalities overexpressed PLAG1, which demonstrates that PLAG1 activation is a frequent event in adenomas irrespective of karyotype. In contrast, PLAG1 was overexpressed in only 2 of 11 malignant salivary gland tumors analyzed, which suggests that, at least in salivary gland tumors, PLAG1 activation preferentially occurs in benign tumors. PLAG1 over-expression was also found in three of nine mesenchymal tumors, i.e., in two uterine leiomyomas and one leiomyosarcoma. RNase protection, rapid amplification of 5'-cDNA ends (5'-RACE), and reverse transcription-PCR analyses of five adenomas with a normal karyotype revealed fusion transcripts in three tumors. Nucleotide sequence analysis of these showed that they contained fusions between PLAG1 and CTNNB1 (one case) or PLAG1 and a novel fusion partner gene, i.e., the gene encoding the transcription elongation factor SII (two cases). The fusions occurred in the 5' noncoding region of PLAG1, leading to exchange of regulatory control elements and, as a consequence, activation of PLAG1 gene expression. Because all of the cases had grossly normal karyotypes, the rearrangements must result from cryptic rearrangements. The results suggest that in addition to chromosomal translocations and cryptic rearrangements, PLAG1 may also be activated by mutations or indirect mechanisms. Our findings establish a conserved mechanism of PLAG1 activation in salivary gland tumors with and without 8q12 aberrations, which indicates that such activation is a frequent event in these tumors.

Amino Acid Sequence↗
PubMed1998

Cloning of a rat brain succinic semialdehyde reductase involved in the synthesis of the neuromodulator gamma-hydroxybutyrate.

The gamma-hydroxybutyrate biosynthetic enzyme succinic semialdehyde reductase (SSR) was purified to homogeneity from rat brain. Peptides were generated by tryptic cleavage and sequenced. PCR primers were designed from the amino acid sequences of two of the peptides showing a similarity (75-85%) to a mitochondrial aldehyde dehydrogenase. A PCR-amplified DNA fragment was generated from recombinant plasmids prepared by a mass excision procedure from a rat hippocampal cDNA library and used as a probe to screen this cDNA library. One cDNA of 1341 bp had an open reading frame encoding a protein of 447 residues with a deduced molecular mass of 47967 Da. The enzyme was expressed in Escherichia coli. Immunoblotting analysis revealed the existence of a protein with the same electrophoretic mobility as the SSR purified from rat brain and with an estimated molecular mass of 45 kDa. Northern blot experiments showed that this enzyme was not expressed in the kidney or in the liver. In the brain tissue, a single but rather broad band was labelled under high stringency conditions, suggesting the presence of more than one messenger species coding for SSR. Hybridization in situ performed on brain tissue slices showed specific labelling of the hippocampus, the upper cortex layer, the thalamus, the substantia nigra, the cerebellum, the pons medulla and the olfactory tract. The recombinant enzyme showed catalytic properties similar to those of the SSR purified from rat brain, particularly in regard to its substrate affinities and Ki for inhibition by phthalaldehydic acid. Valproic acid did not inhibit the cloned SSR. This enzyme had 20-35% identity in highly conserved regions involved in NADPH binding with four other proteins belonging to the aldo-oxo reductase family.

Aldehyde Reductase↗
PubMed1998

A child with a t(11;19)(q14-21;p12) in a pulmonary mucoepidermoid carcinoma.

We report on a mucoepidermoid carcinoma (MEC) of the lung in a 6-year-old girl with a t(11;19)(q14-21;p12) as the sole karyotypic abnormality. An apparently identical t(11;19) has been reported previously in a MEC originating from the major and minor salivary glands. Our findings indicate that the t(11;19) is intimately associated with the mucoepidermoid phenotype and may be used as a diagnostic marker for this tumour type.

Biomarkers, Tumor↗
PubMed1998

Cystoscopy after computed tomography scan to identify bladder invasion in cervical cancer.

OBJECTIVE: To determine the clinical utility of cystoscopy to rule out bladder invasion in cervical cancer patients who have had pelvic computed tomographic (CT) scan. METHODS: We reviewed charts of 49 patients at Walter Reed and Tripler Army Medical Centers who had International Federation of Gynecology and Obstetrics stage II or greater cervical cancer and who underwent both cystoscopy and CT scan before treatment. Data retrieved included diagnosis, race, age, cystoscopy results, and CT scan reports. These patients were evaluated and treated between January 1, 1991, and September 1997. RESULTS: The mean age of the patients was 50 years. Seven of the women were Asian, five black, six white, one Hispanic, and 30 Pacific Islander. There were 40 squamous cell carcinomas and nine adenocarcinomas. There were 25 stage II, 20 stage III, three stage IV, and one recurrent stage II carcinomas. Three patients with bladder invasion were identified by cystoscopy and all also were identified with possible bladder invasion by CT scan. Two additional cases of possible invasion seen on CT scan proved not to be invasion with cystoscopy. The positive predictive valve of CT scan in predicting bladder invasion was 60% (three of five). The negative predictive valve of CT scan in predicting bladder invasion was 100%. CONCLUSION: The utility of performing cystoscopy to rule out bladder invasion in a patient with no evidence of bladder involvement on CT scan is low and might not be necessary.

Adenocarcinoma↗
PubMed1998

Neurochemical and electrophysiological evidence for the existence of a functional gamma-hydroxybutyrate system in NCB-20 neurons.

Clonal neurohybridoma NCB-20 cells express a valproate-insensitive succinic semialdehyde reductase activity that transforms succinic semialdehyde into gamma-hydroxybutyrate. This activity (1.14+/-0.16 nmol/min/mg protein) was similar to the lowest activity existing in adult rat brain. [3H]gamma-Hydroxybutyrate labels a homogeneous population of sites on NCB-20 cell membranes (Kd=250+/-44.4nM, Bmax=180+/-16.2fmol/mg protein) that apparently represents specific gamma-hydroxybutyrate binding sites characterized previously on brain cell membranes. Finally, an Na+-dependent uptake of [3H]gamma-hydroxybutyrate was expressed in NCB-20 cells with a Km of 35+21.1 microM and a Vmax of 80+/-14.2 pmol/min/mg protein. A three-day treatment with 1 mM dibutyryl-cyclic-AMP induced a three-fold increase in the cellular succinic semialdehyde reductase activity. In parallel, a K+-evoked release of [3H]gamma-hydroxybutyrate occurred. This release was Ca2+ dependent and was not present in undifferentiated cells. Cyclic-AMP treatment induced a decrease of [3H]gamma-hydroxybutyrate binding sites, which could be due to spontaneous gamma-hydroxybutyrate release. Patch-clamp experiments carried out on differentiated NCB-20 cells revealed the presence of Ca2+ conductances which were partially inhibited by 50 microM gamma-hydroxybutyrate. This gamma-hydroxybutyrate-induced effect was blocked by the gamma-hydroxybutyrate receptor antagonist NCS-382, but not by the GABA(B) antagonist CGP-55845. These results demonstrate the presence of an active gamma-hydroxybutyratergic system in NCB-20 cells which possesses the ability to release gamma-hydroxybutyrate. These cells express specific gamma-hydroxybutyrate receptors which modulate Ca2+ currents independently of GABA(B) receptors.

Animals↗
PubMed1998

The recurrent translocation t(5;8)(p13;q12) in pleomorphic adenomas results in upregulation of PLAG1 gene expression under control of the LIFR promoter.

We have previously shown that the PLAG1 gene on chromosome 8q12 is consistently rearranged in pleomorphic adenomas of the salivary glands with t(3;8)(p21;q12) translocations. The t(3;8) results in promoter swapping between the PLAG1 gene, which encodes a novel zinc finger protein, and the constitutively expressed gene for beta-catenin (CTNNB1), a protein with roles in cell-cell adhesion and the WG/WNT signalling pathway. In order to assess the importance of other translocation partner genes of PLAG1, and their possible relationship to CTNNB1, we have characterized a second recurrent translocation, i.e. the t(5;8)(p13;q12). This translocation leads to ectopic expression of a chimeric transcript consisting of sequences from the ubiquitously expressed gene for the leukemia inhibitory factor receptor (LIFR) and PLAG1. As for the t(3;8), the fusions occurred in the 5'-noncoding regions of both genes, exchanging regulatory control elements while preserving the coding sequences. The results of the current as well as previous studies indicate that ectopic expression of PLAG1 under the control of promoters of distinct translocation partner genes is a general pathogenetic mechanism for pleomorphic adenomas with 8q12 aberrations.

Adenoma↗
PubMed1997

Observations by chromosome banding, FISH and immunohistochemistry in an adenoid cystic carcinoma with del(17)(p13) as the sole deviation.

We report on an adenoid cystic-carcinoma (ACC) with a clonal deletion of 17p as the only karyotypic abnormality. Using different chromosome 17-derived probes we showed by FISH that the deletion encompassed the p53 tumour suppressor gene. Immunohistochemical analysis revealed overexpression of p53 protein in a subpopulation of cells, suggesting a mutation in the remaining p53 allele in these cells. Our findings provide novel information about possible progressional pathways in ACC, and demonstrate the value of combining conventional cytogenetic analysis with-molecular cytogenetic and immunohistochemical methods. This approach is particularly useful in cases with minor cytogenetic abnormalities at the border of visibility.

Adult↗
PubMed1997

Impact of the in vitro technique used on the cytogenetic patterns in pleomorphic adenomas.

The cytogenetic observations in 97 new cases of pleomorphic adenomas are reported. They were all studied by in vitro technique using enzymatic pretreatment of the explanted material. The results, together with 26 previously reported cases studied by the same method (series II), were compared with a group of 130 adenomas (series I) investigated in cultures of only mechanically dispersed material. The results showed that in series II there was a substantial reduction of normal stemlines, an increase of cases with t(3;8)(p21;q12) and, in particular, of those with other 8q12 involvement. There was a similar frequency of cases with 12q13-15 aberrations in both series whereas, in series II, there was a moderate increase of the cases with "unique" abnormal stemlines. In comparison the German material, comprising 220 cases also studied by the enzymatic method, revealed a much higher frequency of cases with a normal stemline and a much lower frequency of adenomas with 8q12-involvement and of cases with unique stemlines. The results emphasize the need and importance of a meticulous documentation of all details of the in vitro technique used, for instance: explantation methods, composition of media, growth periods in vitro, and methods of harvest.

Adenoma, Pleomorphic↗
PubMed1996

Automated analytical system for the examination of protein primary structure.

This paper describes an automated analytical system for the examination of protein primary structure in which (i) the target protein is first purified by immunoaffinity chromatography, (ii) subsequent chromatographic and chemical reaction steps in the sequencing process are directly coupled, (iii) buffer exchange between these unit operations is achieved while the protein is absorbed on a mixed bed of strong ion exchange sorbents, (iv) proteolysis occurs in an immobilized trypsin column having a 10-1000 fold-excess of enzyme, (v) the tryptic digest is directly transferred to a perfusion dilute capture column where it is concentrated and rapidly desalted, and (vi) peptides eluted from the dilute capture column and analytical microbore and capillary perfusion reversed-phase chromatography columns are analyzed by either single-stage mass spectrometry (MS) or tandem MS/MS. Protein structure variants were easily recognized, and in the case of hemoglobin (Hb) S, the site of variation from Hb A0 was verified.

Amino Acid Sequence↗
PubMed1996

Effect of oxymetazoline nose drops on acute sinusitis in the rabbit.

This investigation was designed to evaluate the effect of the common topical nasal decongestant oxymetazoline hydrochloride on the early local tissue defense in an experimental bacterial infection. For that purpose, a bilateral infection of the maxillary sinus was induced in 14 rabbits. Nose drops (oxymetazoline) were instilled in one nasal cavity, and placebo in the other. After 48 hours, the degree of infection was judged by using a semiquantitative inflammatory score to evaluate histologic preparations of the maxillary sinuses. On the oxymetazoline-treated side, we found a significantly higher degree of inflammation. We conclude that oxymetazoline nose drops, commonly used in acute rhinitis and sinusitis, interfere with the normal defense mechanisms during bacterially induced sinusitis, possibly by a decrease in mucosal blood flow.

Acute Disease↗
PubMed1995

Detection of hidden structural rearrangements by FISH in pleomorphic adenomas.

Previous cytogenetic analysis of pleomorphic adenomas of the salivary glands has revealed a subgroup of tumors with interstitial deletions of 8q with breakpoints at q12 and q21-23. In this paper we have re-examined four adenomas with confirmed or suspected deletions of 8q by FISH. Painting of interphase nuclei and metaphase chromosomes with whole chromosome libraries revealed that in each of the four cases the deleted chromosome 8 material was found inserted or translocated onto other chromosomes. In two of the cases we were also able to resolve several other complex rearrangements. Our FISH data thus suggest that gross deletions of 8q do not occur in pleomorphic adenomas. These observations are of crucial importance for the molecular interpretations of the 8q12 rearrangements. The fact that all rearrangements with breakpoints at 8q12 seem to be translocations or insertions strongly indicates that they involve a similar molecular mechanism. Our findings illustrate that chromosome painting is a valuable and useful adjunct to conventional cytogenetic analysis of solid tumors.

Adenoma, Pleomorphic↗
PubMed1994

Non-random chromosome rearrangements in adenoid cystic carcinoma of the salivary glands.

The chromosomal findings in 10 adenoid cystic carcinomas (ACC) of the salivary glands are described. Clonal numerical deviations as the sole anomaly were detected in four cases and structurally rearranged stemlines and sidelines in four cases. An apparently identical t(6;9)(q23;p21) was found in two tumors; in one case the translocation was part of the abnormal stemline and in the other case it was the sole anomaly in a single variant cell. A similar or identical t(6;9)(q21-24;p13-23) has recently been reported in three of 15 previously published cases of ACC. The three remaining tumors with abnormal stemlines all had rearrangements of chromosome 9, including t(1;9)(q21;p21-22), der(9)i(9)(q10)inv(9)(q12q13), and der(X)t(X;9)(p21;p22-23), respectively. The latter case also had a t(17;18)(p12;q11.2) that was common to both abnormal clones present in this tumor. In addition to other abnormalities, the clone with der(X)t(X;9) also showed a del(6)(q13q21). In two cases fluorescence in situ hybridization (FISH) was used for further characterization of the marker chromosomes. A survey of the present findings together with previous results from 15 ACC clearly demonstrates that rearrangements of 6q21-24 (deletions or translocations in 11 cases), 9p13-23 (translocations in seven cases), and 17p12-13 (translocations in three cases) are recurrent, and often primary, in ACC, and that the t(6;9)(q21-24;p13-23), found in five tumors, is a non-random, primary aberration.

Adult↗