[Recurrent intracerebral haemorrhage in a 24-year-old female patient]. / Rezidivierende intrazerebrale Blutungen bei einer 24-jährigen Patientin.

A 24-year-old female patient from Sierra Leone was referred to the authors' hospital after several unclear intracerebral bleeding events and an echogenic structure on the aortic valve. The patient was receiving oral anticoagulation therapy due to paroxysmal atrial fibrillation and left ventricular noncompaction. Fluorescence in situ hybridization in combination with polymerase chain reaction and sequencing revealed infective endocarditis of the mitral and aortic valve caused by Bartonella quintana. In retrospect, the intracerebral bleeding events could be identified as septic emboli with secondary haemorrhagic transformation under anticoagulation therapy. The patient showed significant clinical improvement and no further bleeding events occurred after receiving biological mitral and aortic valve replacement and several weeks of doxycycline and gentamicin antibiotic therapy.

The branched-chain amino acid transaminase 1 sustains growth of antiestrogen-resistant and ERα-negative breast cancer.

Antiestrogen-resistant and triple-negative breast tumors pose a serious clinical challenge because of limited treatment options. We assessed global gene expression changes in antiestrogen-sensitive compared with antiestrogen-resistant (two tamoxifen resistant and two fulvestrant resistant) MCF-7 breast cancer cell lines. The branched-chain amino acid transaminase 1 (BCAT1), which catalyzes the first step in the breakdown of branched-chain amino acids, was among the most upregulated transcripts in antiestrogen-resistant cells. Elevated BCAT1 expression was confirmed in relapsed tamoxifen-resistant breast tumor specimens. High intratumoral BCAT1 levels were associated with a reduced relapse-free survival in adjuvant tamoxifen-treated patients and overall survival in unselected patients. On a tissue microarray (n=1421), BCAT1 expression was detectable in 58% of unselected primary breast carcinomas and linked to a higher Ki-67 proliferation index, as well as histological grade. Interestingly, BCAT1 was predominantly expressed in estrogen receptor-α-negative/human epidermal growth factor receptor-2-positive (ERα-negative/HER-2-positive) and triple-negative breast cancers in independent patient cohorts. The inverse relationship between BCAT1 and ERα was corroborated in various breast cancer cell lines and pharmacological long-term depletion of ERα induced BCAT1 expression in vitro. Mechanistically, BCAT1 indirectly controlled expression of the cell cycle inhibitor p27Kip1 thereby affecting pRB. Correspondingly, phenotypic analyses using a lentiviral-mediated BCAT1 short hairpin RNA knockdown revealed that BCAT1 sustains proliferation in addition to migration and invasion and that its overexpression enhanced the capacity of antiestrogen-sensitive cells to grow in the presence of antiestrogens. Importantly, silencing of BCAT1 in an orthotopic triple-negative xenograft model resulted in a massive reduction of tumor volume in vivo, supporting our findings that BCAT1 is necessary for the growth of hormone-independent breast tumors.

Molecular-cytogenetic comparison of mucosa-associated marginal zone B-cell lymphoma and large B-cell lymphoma arising in the gastro-intestinal tract.

Extranodal B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type may represent a model of lymphoma progression, because a small cell component frequently occurs in the large cell variants. We studied 52 extranodal B-cell lymphomas: 18 extranodal marginal zone B-cell lymphomas of MALT type (MZBL,MT), 7 MZBL,MT of the gastro-intestinal tract with a diffuse large B-cell component (giMZBLplusLBCL), and 27 diffuse large B-cell lymphomas of the gastro-intestinal tract without small cell component (giLBCL). Analytical techniques were comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The translocation t(11;18) was found as the sole aberration in two MZBL,MT only. In contrast to this, t(11;18)-negative MZBL,MT were characterized by frequent gains on chromosome 3 and DNA amplifications on 2p13-p15. Furthermore, we found a clonal lymphoma progression from the small to the large cell component with accumulation of gains and losses of chromosomal material in the large cell component in giMZBLplusLBCL. Aberrations overlapping with MZBL,MT and giMZBLplusLBCL included losses on chromosome 13, amplifications of the REL proto-oncogene, or gains on chromosome 12. In addition, the large cell component revealed gains on 8q24, including amplifications of the MYC proto-oncogene, and losses on 2q. The giLBCL had frequent gains on chromosomes 12 and 9, as well as on 11q, and losses on 6q. We conclude that, based on the distinctive and partly overlapping patterns of genetic aberrations, MALT lymphomas can be divided into different genetic subgroups.

Expression patterns of murine lysosome-associated membrane protein 2 (Lamp-2) transcripts during morphogenesis.

We report the isolation and characterization of the murine homologues to human and chicken lysosome-associated membrane protein (Lamp)-2 transcripts and their prevalent expression patterns during development. Lamp-2 transcripts code for proteins predominant in and specific for the lysosomal membrane. The function of these proteins is still under investigation. Other than in the lysosomal membrane, Lamp-2 proteins have been detected at the plasma membrane of cells in a differentiation dependent and activation dependent manner. They were also observed at the plasma membrane of cells, which secrete lysosomal hydrolases. Involvement of Lamp-2 in cell adhesion during such events has been proposed. A study of the developmental expression patterns of m-Lamp-2 transcripts was undertaken to help elucidate possible functions of their respective proteins. The m-Lamp-2b transcript was prevalent in neural crest derived ganglia. The m-Lamp-2a and -2c transcripts were similarly expressed in structures containing neural crest derived tissue with the strongest signals detected in thymus. However, m-Lamp-2a and -2c transcript expression differed in mesoderm or endoderm derived mesenchymal and epithelial tissues. M-Lamp-2c expression was pronounced in mesenchyme early in development, in limb connective tissue, and in lung parenchyma, whereas m-Lamp-2a was prevalent in the liver, the pancreas, and in differentiating kidney epithelium, and became increasingly prominent in the epithelial lining of the digestive and the respiratory tract during development. These results correlated with the detection of m-Lamp-2 protein in these tissues. In conclusion, all m-Lamp-2 transcripts were detected in tissues undergoing apoptosis during development requiring phagolysosome involvement. In addition, m-Lamp-2a and m-Lamp-2c transcripts were observed in epithelium and mesenchyme during the time of epithelial-mesenchymal interaction, mesenchymal-epithelial transformation, and branching. Their expression pattern became more tissue and cell type specific as differentiation progressed. These patterns indicate a possible involvement of m-Lamp-2 proteins in cell/cell or cell/extracellular matrix interaction, and appear to reflect tissue and cell type specific roles of lysosomes during morphogenesis.

Characteristic pattern of chromosomal gains and losses in primary large B-cell lymphomas of the gastrointestinal tract.

In contrast to low-grade B-cell lymphomas originating in the gastrointestinal (GI) tract, only few cytogenetic data are available for the large cell, highly malignant variants. We studied 31 large B-cell lymphomas of the GI tract by comparative genomic hybridization (CGH) and fluorescence in situ hybridization using specific DNA probes (FISH). The most frequent aberrations were gains of all or of parts of chromosomes 11 (11 cases), 12 (9 cases), 1q (4 cases), and 3q (4 cases). Losses of parts of chromosome 6q and of parts of the short arm of chromosome 17 (6 cases each) were found most frequently. In four cases a total of seven high-level DNA amplifications was detected. In two of these cases, involvement of specific protooncogenes (REL and MYC) was shown. Some genetic aberrations seemed to be associated with an inferior clinical course: patients with >/=2 aberrations had a significantly shorter median survival. Furthermore, all patients with gains of all or parts of chromosome arm 1q and with high-level DNA amplifications as well as seven of nine patients with gains of all or parts of chromosome 12 died of lymphoma. In conclusion, the pattern of chromosomal gains and losses in large B-cell lymphomas was different from data reported for low-grade (MALT) lymphomas of the stomach and bowel, especially with respect to the high incidence of partial gains of chromosome arm 11q and of all or parts of chromosome 12 and the low frequency of polysomy 3. In addition, our data suggest that chromosomal gains and losses detected by CGH and FISH may predict for the outcome of patients with this tumor entity.

An alternatively spliced form of the human lysosome-associated membrane protein-2 gene is expressed in a tissue-specific manner.

We report the isolation of an alternatively spliced human lysosome-associated membrane protein-2 (h-lamp-2) transcript which is overexpressed in human muscle. The cloning of this transcript is an indication for the tissue-specific expression of lysosomal membrane proteins and implicates the possibility of multiple functions for the protein products of the h-lamp-2 gene, as well as other lysosome-associated membrane proteins. The new transcript, designated h-lamp-2b, results from the alternative splicing of the last exon, exon 9, the alternative form of which is approximately 2800 bp in length. The resulting protein is identical in length to the previously reported h-lamp-2 protein, 410 amino acids including the leader peptide. This final exon, which encodes the last eleven amino acids of the luminal domain, the 24 amino acid transmembrane spanning region, and an eleven amino acid cytoplasmic tail, shows complete conservation of the Gly.Tyr.X.X lysosomal targeting signal with regard to its position relative to the transmembrane spanning region and the carboxy terminus of the protein. Immune electron microscopy studies verified localization of this alternative gene product to the lysosomal membrane.

Complete cDNA sequence of human lysosome-associated membrane protein-2.

The isolation and sequencing of 15 independent human lysosome-associated membrane protein-2 (h-lamp-2) recombinants from a primary human liver cDNA library has resulted in the determination of a transcript sequence significantly longer than previously reported and reveals the utilization of each of the four potential polyadenylation signals (AATAAA) present in the 3' untranslated region. The most 5' extending cDNA clone initiates upstream of the proposed transcription initiation site. A number of differences with published sequences for the h-lamp-2 transcript were observed, some of which result in amino acid changes in the predicted primary structure of the h-lamp-2 protein, and two of which give rise to restriction fragment length polymorphisms. The knowledge of these sequence alterations and polymorphisms is an important consideration for the further analysis of the h-lamp-2 locus with regard to the delineation of function and association with human inherited disorders.

DNA sequence polymorphisms in exonic and intronic regions of the human phenylalanine hydroxylase gene aid in the identification of alleles.

Five sequence polymorphisms at the phenylalanine hydroxylase (PAH) gene locus were observed to be in tight association with specific alleles of this locus. Since these polymorphisms can be detected using polymerase chain reaction (PCR) methodology, application of a combination of these polymorphisms reduces the effort involved in PAH DNA haplotype analysis, which is needed for population genetic analysis or diagnosis of the disease status. In addition our results indicate the evolution of haplotype 3, 4 and 7 PAH alleles from a common ancestor, whereas PAH haplotypes 5, 6, and 11 arose from another common ancestor allele. These data reveal that two of the polymorphisms investigated originated before the separation of races.

The identification of two mis-sense mutations at the PAH gene locus in a Turkish patient with phenylketonuria.

DNA sequence analysis of the 13 exons and intron/exon boundaries of the phenylalanine hydroxylase (PAH) gene has detected two base transitions, resulting in mis-sense mutations, in the genomic DNA of a Turkish patient (E1) with phenylketonuria (PKU). The Leu48----Ser amino acid substitution was associated with the mutant haplotype 3 allele and the Glu221----Gly amino acid substitution with the mutant haplotype 4 allele of this family. Allele-specific oligonucleotide (ASO) dot-blot analysis subsequently detected the Leu48----Ser mutation in the haplotype 4 PKU alleles of nine (18.8%) of the 48 unrelated Caucasian PKU families investigated. This mutation results in mild PKU in the homozygous state. The Glu221----Gly mutation has only been detected within patient E1 and his father.

Direct detection of a major mutation responsible for phenylketonuria in the population of the Federal Republic of Germany.

Forty-six individuals having phenylketonuria (PKU) alleles at the phenylalanine hydroxylase (PAH) locus were tested for the haplotype 2 PKU mutation by allele-specific hybridization following in vitro DNA amplification. Patients and carriers previously shown to have a mutant haplotype 2 PAH allele demonstrated conservation of this mutation. In vitro DNA amplification greatly facilitated this analysis and provides the possibility of population screening for 37% of the mutant German PAH alleles.

DNA haplotype analysis at the phenylalanine hydroxylase locus in the Turkish population.

Thirty-nine Turkish phenylketonuria (PKU) families were investigated for their DNA haplotypes at the phenylalanine hydroxylase (PAH) locus. There was a threefold higher incidence of consanguinity in the population studied compared with the general Turkish population. The PAH DNA haplotype 6 was found to be almost exclusively associated not only with the mutant PAH genes but also with the classic phenotype in 39% of the Turkish patients. This haplotype was of not importance in northern European populations. The two DNA haplotypes (1 and 4) that were almost equally frequent among the normal and the mutant PAH genes in northern European populations show virtually the same distribution in Turkish individuals. In all populations studied, these haplotypes are associated with different phenotypes.

Linkage disequilibrium between mutation and RFLP haplotype at the phenylalanine hydroxylase locus in the German population.

Restriction fragment length polymorphism (RFLP) haplotypes at the phenylalanine hydroxylase (PAH) locus have been determined in 60 German families with PAH deficiency. Similar to the Danish population, about 90% of the mutant alleles are confined to four distinct haplotypes. There are however, differences in the frequency distribution of these haplotypes among the mutant alleles between the two populations. Using an oligonucleotide probe for the splicing mutation associated with mutant haplotype 3 in the Danish population, a tight association between the mutation and the RFLP haplotype has also been observed in Germany. The results provide strong evidence that the splicing mutation occurred on a haplotype 3 chromosome and that the mutant allele has spread into different populations among Caucasians.