Biomedical subjects

K Oberg

Publications and source records attributed to K Oberg.

4 recordsLinked to original sources

PubMed1992

Expression of platelet-derived growth factor and its receptors in neuroendocrine tumors of the digestive system.

Carcinoid tumors are slowly growing neuroendocrine neoplasms which often present pronounced fibrosis around the tumor cells. We have previously shown by immunohistochemistry that carcinoid tumors express platelet-derived growth factor (PDGF) beta-receptors on surrounding stromal cells. In this report, 22 midgut carcinoids and 5 endocrine pancreatic tumors were examined for the presence of PDGF with a monoclonal antibody raised against a peptide corresponding to a part of the B-chain of PDGF which reacts strongly with the B-chain and weakly with the A-chain. They were also examined for PDGF alpha-receptors with an affinity-purified polyclonal peptide antibody and for PDGF beta-receptor with the monoclonal antibody PDGFR-B2. PDGF was expressed on tumor cells and on adjacent stroma. PDGF alpha-receptor was seen on clusters of tumor cells and occasionally on adjacent stroma, whereas beta-receptors were seen only in the stroma. Tissue sections from some of these midgut carcinoids were also investigated by in situ hybridization for mRNA of PDGF A- and B-chains as well as alpha- and beta-receptors. By in situ hybridization, abundant expression of mRNA for PDGF beta-receptor and PDGF A-chain was observed in stromal cells adjacent to carcinoid tumor cell clusters, but the mRNA expression in the tumor cells themselves was at a low level. A few clustered tumor cells and stromal cells expressed mRNA for the PDGF alpha-receptor, thus consolidating the immunohistochemical findings. mRNA for the PDGF B-chain was detected in both tumor cells and stroma, but only at low levels. Our data suggest that PDGF is involved in the growth stimulation of the carcinoid tumor cells in an autocrine fashion and in the stimulation of stromal cell growth through paracrine and possibly autocrine mechanisms. Moreover, remarkably strong immunostaining of PDGF and the PDGF alpha-receptor was seen on peripheral nerve fibers.

Adult↗

PubMed1992

A study of biological behavior based on the expression of a proliferating antigen in neuroendocrine tumors of the digestive system.

The expression of a proliferating antigen by Ki-67 immunohistochemistry was evaluated in 32 gastrointestinal carcinoids and in 5 pancreatic islet cell tumors. In the tissue sections the number of labelled nuclei was calculated per tumor area. The tumors were classified as low proliferating (less than 0.3 labelled cells/mm2), medium proliferating (0.3-1 labelled cells/mm2), and high proliferating (greater than 1 labelled cell/mm2). In 26 tumors obtained from patients receiving antitumor therapy (alpha-interferon) the proliferative activity was decreased. In treated midgut carcinoids the proliferative activity in metastatic tissue was significantly reduced (p less than 0.05). Though not statistically significant, primary midgut carcinoids collected from untreated patients displayed a lower proliferative activity than liver metastases. A survival analysis revealed that patients with tumors displaying low proliferative activity had a better survival than those with high proliferative activity (p less than 0.05). Single cell cytofluorometric DNA analyses showed regular diploid stem cell lines in the majority of tumors from untreated patients (9/11 cases). No correlation was found between the calculated proliferative activity and the DNA profile. The obtained results indicate that the expression of a proliferation antigen by Ki-67 immunohistochemistry can be used to evaluate the biological behavior of neuroendocrine tumors of the digestive system and predict survival.

Adenoma, Islet Cell↗

PubMed1979

Streptozotocin treatment of a pancreatic tumour producing VIP and gastrin associated with Verner-Morrison syndrome.

A 57-year-old male patient with metastasizing non-beta islet cell carcinoma of the pancreas is described. Both gastrin and VIP levels were elevated and the patient suffered from a syndrome of pancreatic cholera and hyperacidity. The tumour contained gastrin and VIP as demonstrated by immunofluorescence. The patient also had a history of familial renal stone formation and parathyroid nodular hyperplasia. Resection of pancreatic tumour in 1973 resulted in four years without symptoms. In 1977 definite signs of multiple hepatic metastases appeared. These signs disappeared after streptozotocin given in a dosage of 2 g three times at weekly intervals. The patient had remained well for 20 months after this treatment. The causative agents for the clinical syndrome in this case are discussed in view of circulating hormone levels.

Acute Kidney Injury↗

PubMed1977

Effects of a new beta1-selective beta-blocker H 87/07 in angina pectoris.

The efficacy and toleration of a new beta1-selective beta-blocker, H 87/07, was compared with placebo in 33 patients with angina pectoris. The efficacy was evaluated using subjective assessments of attack rate and nitroglycerin consumption as well as objective assessments of exercise tolerance on a bicycle ergometer. H 87/07 significantly reduced the attack rate and the nitroglycerin consumption compared with placebo. The mean reduction amounted to 13 and 36% respectively. No significant differences were found between H 87/07 and placebo with regard to exercise tolerance. Due to high intrinsic stimulating activity (I.S.A.) H 87/07 altered the heart rate and blood pressure only slightly at rest but during exercise significant reductions were seen. Except for one patient who had cardiac decompensation on H 87/07 no side-effects of clinical importance were seen. No significant changes were seen with regard to the laboratory tests performed.

Adrenergic beta-Antagonists↗