[Thymus cancers: A clinical observation]. / Thymustumoren : Eine klinische Betrachtung.

INTRODUCTION: Thymic tumors including thymomas, thymic carcinomas, and thymic carcinoid tumors are rare tumors with an incidence of 0.13/100,000. MATERIALS AND METHODS: A literature search was performed to identify recent findings on epidemiology, classification, and various therapeutic approaches. RESULTS: These tumors with a wide spectrum of histologic and biologic features may be clinically unapparent for a long time or show a very aggressive behavior with local invasion and distant metastases. Surgical resection is the mainstay in stage I and II thymomas, whereas in stage III thymomas and in thymomas with pleural dissemination surgery in context of a multimodal treatment should be discussed. Thymic tumors are chemoreactive. Targeted therapies show poor results and should only be considered in the palliative situation after failure of chemotherapy. CONCLUSION: The new TNM (T: tumor, N: node, M: metastasis) classification of thymic tumors will help to identify the best treatment options.

Increased elongation of N-acetyllactosamine repeats in doubly glycosylated lysozyme with a particular spacing of the glycosylation sites.

Lysozyme is an example of an extensively studied secretory enzyme. Glycosylated mutant human lysozyme has been used as a model in studies on the biosynthesis of N-acetyllactosamine repeats in N-linked oligosaccharides. We examined the biosynthesis of the repeats in two doubly glycosylated mutants and describe here a rapid purification and separation of singly and doubly glycosylated molecules. In one of the mutants, the elongation of the repeats is enhanced if the molecules are doubly glycosylated, but not if the carbohydrate is attached to either site individually. This enhancement is not seen in the other doubly glycosylated mutant. Since lysozyme is not structurally related to glycoproteins bearing carbohydrate with N-acetyllactosamine repeats, we propose that in multivalent substrates the synthesis of the repeats can be promoted by a proper spacing of the elongated carbohydrate antennae in addition to any role of the protein backbone.

Molecular organization of the human cathepsin D gene.

A 16-kb fragment of human DNA containing the cathepsin D (CATD) gene was isolated. Nucleotide sequencing, primer extension, protection from mung bean nuclease, and promoter activity assays were used to characterize the gene. The transcribed portion of the gene is about 11,000 bp and is organized into 9 exons analogous with the human pepsinogen A gene. Human pepsinogen A and CATD proteins have 42% sequence identity, while the two cDNAs are 55.7% identical. The positions of the splice junctions are fully conserved in these two genes. The noncoding sequences of the two genes are dissimilar. We report the nucleotide sequence of an Eco RI-Bam HI fragment that contains the transcription initiation site. The promoter region contains no TATA and CCAAT boxes, but five potential Sp1 binding sites (one of them in the first intron) and four AP-2 binding sites (two of them in the first intron). In COS-1 cells, the region containing the three proximal Sp1 sites possesses the bulk of the promoter activity of the 5'-flanking sequence. The transcription start site of the CATD gene is localized within a CpG cluster. In the interval -390 through +450, the content of CpG is 5.8 times above the average throughout the human genome.