Biomedical subjects

Heinz-Herbert Homann

Publications and source records attributed to Heinz-Herbert Homann.

4 recordsLinked to original sources

PubMed2005

Inhibition of early steps in the lentiviral replication cycle by cathelicidin host defense peptides.

BACKGROUND: The antibacterial activity of host defense peptides (HDP) is largely mediated by permeabilization of bacterial membranes. The lipid membrane of enveloped viruses might also be a target of antimicrobial peptides. Therefore, we screened a panel of naturally occurring HDPs representing different classes for inhibition of early, Env-independent steps in the HIV replication cycle. A lentiviral vector-based screening assay was used to determine the inhibitory effect of HDPs on early steps in the replication cycle and on cell metabolism. RESULTS: Human LL37 and porcine Protegrin-1 specifically reduced lentiviral vector infectivity, whereas the reduction of luciferase activities observed at high concentrations of the other HDPs is primarily due to modulation of cellular activity and/ or cytotoxicity rather than antiviral activity. A retroviral vector was inhibited by LL37 and Protegrin-1 to similar extent, while no specific inhibition of adenoviral vector mediated gene transfer was observed. Specific inhibitory effects of Protegrin-1 were confirmed for wild type HIV-1. CONCLUSION: Although Protegrin-1 apparently inhibits an early step in the HIV-replication cycle, cytotoxic effects might limit its use as an antiviral agent unless the specificity for the virus can be improved.

Animals↗

PubMed2005

Dedifferentiated liposarcoma with extensive lymphoid component.

An unusual variant of dedifferentiated liposarcoma with extensive lymphocytic component is described. A 71-year-old patient suffered from a relapse of an atypical lipomatous tumor/well-differentiated liposarcoma with early micronodular (low-grade) dedifferentiation, which had been resected 4 years before. The relapse revealed features of a dedifferentiated liposarcoma with spindle-cell, partly pleomorphic dedifferentiation and osseous metaplasia. Clearly separated from the spindle-cell areas, an extensive homogeneously dense lymphoid (lymphocytic) tumor-component was evident, with relative abrupt transition to the well-differentiated liposarcoma component. Using immunohistochemistry and PCR, the lymphoid ("lymphoma-like") infiltrate proved to be a polyclonal lymphocytic proliferation. Fluorescence in situ hybridization (FISII) analysis revealed no signs of MDM2- and CDK4-gene amplification in the lymphoid areas, although within this mononuclear lymphoid population, large polymorphic nuclei displayed an amplified number of MDM2/CDK4 gene copies, indicating the presence of truly dedifferentiated tumor cells within the lymphoid component. The results favor a reactive lymphocytic infiltration versus a neoplastic one, which might be caused for example by chemoattractive agents. An extensive lymphoid "overgrowth" must be considered within the spectrum of unusual variants and in the differential diagnosis of dedifferentiated liposarcoma.

Aged↗

PubMed2002

Pigmented (melanotic) neurofibroma. Report of an unusual case with immunohistochemical, ultrastructural and cytogenetic analyses.

In the spectrum of neurofibromas, pigmented tumors are rare variants usually showing only faint, macroscopically obvious pigmentation. We report a case of a huge pigmented neurofibroma with extended, macroscopically striking pigmentation in a patient with stigmata of neurofibromatosis. The immunohistochemical and ultrastructural findings support a melanotic line of differentiation besides schwann cell differentiation and indicate a phenotypic neoplastic spectrum between tumorous schwann cells and melanocytes. Using comparative genomic hybridization, striking chromosomal aberrations were not detected. High level amplifications of the known chromosomal regions, including genes of major enzymes responsible for melanin synthesis, appear to be unlikely. However, smaller chromosomal defects might have been overlooked by the limited resolution of this screening method. Therefore, other mechanisms up-regulating melanogenesis, such as mutations in regulatory genes, have to be considered.

Adult↗

PubMedDate not supplied

Preoperative oral supplementation with long-chain Omega-3 fatty acids beneficially alters phospholipid fatty acid patterns in liver, gut mucosa, and tumor tissue.

BACKGROUND: The uptake of omega-3 polyunsaturated fatty acids (PUFAs) into the liver, gut mucosa, and tumor tissue and plasma levels after preoperative administration of supplemented enteral nutrition was investigated in patients with malignancies of the upper gastrointestinal tract. The objective of the study was to evaluate the incorporation of preoperatively administrated PUFAs, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) into cell phospholipids. METHODS: Patients undergoing major gastrointestinal surgery (n = 40) were prospectively randomized to receive a PUFA-supplemented liquid oral diet 5 days preoperatively or an isocaloric control diet. The planned diet intake was 1000 mL/d providing 3.7 g of PUFA. The diet was given in addition to the usual hospital diet. The phospholipid fractions in plasma were analyzed on the day of surgery. Tissue samples of liver, gut mucosa (small intestine), and tumor were taken during surgery and homogenized. EPA and DHA content was analyzed using liquid gas chromatography. RESULTS: Both patient groups (PUFA group: n = 20; control group: n = 20) were similar in age, weight, and surgical procedures. As compared with the control group, the PUFA group had significantly increased levels of EPA in liver tissue (0.4 vs 1.3 weight %), gut mucosa (0.3 vs 1.0 weight %), and tumor tissue (0.3 vs 0.8 weight %). Also, the DHA levels in the PUFA group were significantly higher than the control group: liver tissue (4.1 vs 7.5 weight %), gut mucosa (2.1 vs 3.7 weight %) and tumor tissue (1.9 vs 4.2 weight %). CONCLUSIONS: This study suggests that administration of PUFA-enriched diets leads to increased incorporation of EPA and DHA not only in liver and gut mucosa tissue, but also in tumor tissue in patients with solid gastrointestinal tumors. Thus, preoperative administration of oral PUFA-enriched diets could have an impact on the postoperative inflammatory response after major abdominal surgery.

Administration, Oral↗