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Biomedical subjects

H Tammen

Publications and source records attributed to H Tammen.

16 recordsLinked to original sources
PubMed1999

Proteolytic cleavage of glucagon-like peptide-1 by pancreatic beta cells and by fetal calf serum analyzed by mass spectrometry.

Fetal calf serum and a beta-cell line exhibit a proteolytic activity essential for the biological function of glucagon-like peptide-1 (GLP-1). This process of cleavage was investigated using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To generate processing products, GLP-1 was subjected to rat insulinoma m5F (RINm5F) cell cultures or to fetal calf serum (FCS). For detection of processing products, a standardized extraction method including ion-exchange batch extraction, ultrafiltration, gel filtration, and reversed-phase chromatography was used. The RP fractions were analyzed by MALDI-TOF-MS. Processed proteolytic products were detected by comparing the resulting mass spectra of cell media or FCS after 2 h incubation with GLP-1 (7-36) amide with these of 2 h controls. To perform the comparison of the resulting mass spectra, software (MASSSPECANALYST) based on Microcal Software, Origins C-like language LABTALK was developed. GLP-1 fragments were purified by RP-HPLC, and characterized by sequence analysis. As insulin is the major secretory product of beta cells depending on GLP-1 stimulation, the insulin and insulin fragments of the cell culture supernatants were also analyzed by this method.

Amino Acid Sequence↗
PubMed1999

Composition of the peptide fraction in human blood plasma: database of circulating human peptides.

A database was established from human hemofiltrate (HF) that consisted of a mass database and a sequence database, with the aim of analyzing the composition of the peptide fraction in human blood. To establish a mass database, all 480 fractions of a peptide bank generated from HF were analyzed by MALDI-TOF mass spectrometry. Using this method, over 20000 molecular masses representing native, circulating peptides were detected. Estimation of repeatedly detected masses suggests that approximately 5000 different peptides were recorded. More than 95% of the detected masses are smaller than 15000, indicating that HF predominantly contains peptides. The sequence database contains over 340 entries from 75 different protein and peptide precursors. 55% of the entries are fragments from plasma proteins (fibrinogen A 13%, albumin 10%, beta2-microglobulin 8.5%, cystatin C 7%, and fibrinogen B 6%). Seven percent of the entries represent peptide hormones, growth factors and cytokines. Thirty-three percent belong to protein families such as complement factors, enzymes, enzyme inhibitors and transport proteins. Five percent represent novel peptides of which some show homology to known peptide and protein families. The coexistence of processed peptide fragments, biologically active peptides and peptide precursors suggests that HF reflects the peptide composition of plasma. Interestingly, protein modules such as EGF domains (meprin Aalpha-fragments), somatomedin-B domains (vitronectin fragments), thyroglobulin domains (insulin like growth factor-binding proteins), and Kazal-type inhibitor domains were identified. Alignment of sequenced fragments to their precursor proteins and the analysis of their cleavage sites revealed that there are different processing pathways of plasma proteins in vivo.

Amino Acid Sequence↗
PubMed1990

Immunobiotherapy with Uro-Vaxom in recurrent urinary tract infection. The German Urinary Tract Infection Study Group.

A series of 120 patients with recurrent urinary tract infection (UTI), all in acute recurrence at the start of the trial, were treated for 3 months under double-blind conditions with 1 capsule daily of either the immunobiotherapeutic product Uro-Vaxom (UV) or a placebo. They were then observed for 3 months without treatment. During the 6 months of the trial a significant decrease was noted in the UV group compared with the placebo group with respect to the number of recurrences of UTI, total consumption of antibiotics and chemotherapeutic agents, bacteriuria and dysuria. By the sixth month the UV patients were receiving no antibiotics. The final assessment was that UV was significantly more effective than the placebo. UV was well tolerated, with possible mild side effects in only 4 patients. During a further observation period of 5 months, patients who had received UV during the first period had fewer recurrences of UTI than those who had received placebo, confirming the long-term protective action of UV.

Adjuvants, Immunologic↗