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Biomedical subjects

W Böhm

Publications and source records attributed to W Böhm.

At least 19 recordsLinked to original sources
PubMed2000

Axilloscopy and endoscopic sentinel node detection in breast cancer patients.

BACKGROUND: Sentinel node biopsy is a promising technique that allows the axillary status of breast cancer patients to be predicted with high accuracy. Reducing false negative results remains a major challenge for the improvement of this procedure. Furthermore, new techniques are required to achieve axillary clearing with less morbidity in cases of unsuccessful mapping or multicentric carcinoma. We analyzed whether axilloscopy and endoscopic sentinel node biopsy is a feasible procedure for visualization of the axillary space and resection of the sentinel node using endoscopic techniques. METHODS: Following blue dye-guided lymphography and liposuction of the axillary fat, endoscopic axillary sentinel node biopsy was performed in 35 breast cancer patients. We then assessed the exposure of anatomical landmarks, the detection rate of the sentinel node, the false negative rate, and the accuracy of consecutive axillary clearing. RESULTS: In almost every case, an excellent anatomical orientation was achieved. The detection rate for the sentinel node was 83.3%. In one case, the sentinel node did not reflect the status of the residual axilla. A mean number of 17.1 lymph nodes was harvested at consecutive axillary clearing. CONCLUSIONS: Axilloscopy and endoscopic sentinel node biopsy, following liposuction of the axillary fat, is a feasible procedure that allows identification and minimally invasive resection of the sentinel node with high accuracy. The endoscopic approach might help to minimize the pitfalls of sentinel node biopsy by visualizing the axillary space. In future, it may become a technique that enables minimally invasive axillary clearing when complete lymphadenectomy is required.

Adult↗
PubMed2000

Fluorescence diagnosis of endometriosis on the chorioallantoic membrane using 5-aminolaevulinic acid.

The chorioallantoic membrane (CAM) is a useful model for the fluorescence diagnosis of experimentally induced endometriosis. In our experimental setup 75.7% of the histologically examined tissue preparations were viable and only 24.3% showed signs of necrosis on the CAM after various periods of incubation. Best results were obtained when grafting to the CAM was performed between days 7 and 9 and when implants were left on the CAM for 3-5 days (P < 0.05). We were able to demonstrate that 5-aminolaevulinic acid (ALA) is stored selectively in ectopic endometrium. The subsequent fluorescence of the endometrium shows a rapid increase that reaches a peak after 10-14 h which can be clearly differentiated from the weaker fluorescence of grafted normal peritoneum and fimbriae (P < 0.01).

Adult↗
PubMed1999

SiMa, a new neuroblastoma cell line combining poor prognostic cytogenetic markers with high adrenergic differentiation.

We describe the establishment and characterization of a new neuroblastoma (Nb) cell line, SiMa, carrying the major recurrent chromosome changes associated with poor prognosis Nb, including amplification of N-MYC by formation of double minutes (dmin), der(1)t(1;17)(p35;q12) and der(22)t(17;22)(q22;p13), and loss of chromosome 11, documented at both initiation and late passage. In contrast to these cytogenetic stigmata of poor prognosis, analysis of catecholamine synthesis by high pressure liquid chromatography (HPLC) measurement revealed an advanced degree of adrenergic differentiation with high rates of 3,4-Dihydroxyphenylalanine (DOPA), noradrenaline, homovanillic acid (HVA), and vanillylmandelic acid (VMA) production. Contrastingly advanced differentiation and poor prognostic genetic markers combine to render SiMa a unique instrument for investigating the pathology and therapy of Nb.

Cell Differentiation↗
PubMed1999

[Endoscopic axillary lymph node excision--results of a pilot study].

OBJECTIVE: Assessment of axillary nodal status with reduced shoulder-arm-morbidity remains a major challenge for primary surgery of breast cancer patients. In a pilot study endoscopic axillary lymph node dissection was evaluated. MATERIAL AND METHODS: In 30 breast cancer patients axillary lymphadenectomy was performed after liposuction using an endoscopic approach. During a learning phase of 15 cases an open revision was routinely carried out. Later complete endoscopic lymph node dissection was performed. The exposition of anatomical landmarks, the number of resected lymph nodes, postoperative lymphorrhea, histopathological signs of traumatisation were assessed as well as intra and postoperative complications. RESULTS: In any case we found excellent exposure of anatomical landmarks. Following a learning curve of 15 cases the average number of resected lymph nodes was equal to the average number of lymph nodes resected with conventional techniques (18.2 vs. 18.4, median 17 vs 18). Minimal intraoperative complications were observed. Postoperative lymphorrhea and seroma rate were not remarkably reduced in comparison with open procedures. CONCLUSIONS: Our study demonstrates, that endoscopic lymph node dissection may be performed with a low complication rate and with identical accuracy as achieved by open techniques.

Axilla↗
PubMed1998

T cell-mediated, IFN-gamma-facilitated rejection of murine B16 melanomas.

The murine melanoma cell line B16.F10 (H-2b) was used to study specific T cell responses that reject tumors. Stable B16 transfectants were established that express viral Ags, either the hepatitis B surface Ag (HBsAg) or the large tumor Ag (T-Ag) of SV40. B16 cells and their transfected sublines were CD40+ CD44+ but expressed no (or low levels of the) costimulator molecules CD154 (CD40L), CD48, CD54, CD80, and CD86. Surface expression of MHC class I (Kb, Db) and class II (I-Ab) molecules by B16 cells was low, but strikingly up-regulated by IFN-gamma. CD95 (Fas) and CD95 ligand (CD95L (FasL)) were "spontaneously" expressed by B16 cells growing in vitro in serum-free medium; these markers were strikingly up-regulated by IFN-gamma. B16 cells coexpressing CD95 and CD95L were irreversibly programmed for apoptosis. In vitro, noninduced B16 transfectants stimulated a specific IFN-gamma release response, but no cytolytic response (in a 4-h assay) in MHC class I-restricted CTL; in contrast, IFN-gamma-induced B16 targets were efficiently and specifically lysed by CTL. In vivo, B16 transfectants were specifically rejected by DNA-vaccinated syngeneic hosts through a T-dependent immune effector mechanism. The tumors showed evidence of massive apoptosis in vivo during the rejection process. The data suggest that CTL-derived IFN-gamma enhances an intrinsic suicide mechanism of these tumor cells in addition to facilitating lytic interactions of effectors with tumor targets.

Animals↗
PubMed1998

Ascorbic acid stimulates DOPA synthesis and tyrosine hydroxylase gene expression in the human neuroblastoma cell line SK-N-SH.

Ascorbic acid is well known to induce noradrenaline synthesis in sympathetic nervous cells. In a series of experiments we found that incubation of the neuroblastoma cell line SK-N-SH with ascorbic acid (100-500 microM) for 2 h results in a significantly enhanced synthesis of 3,4-dihydroxyphenylalanine (DOPA) and dopamine. Additionally, cDNA-polymerase chain reaction (cDNA-PCR) analysis of relative mRNA levels corresponding to the enzymes involved in catecholamine synthesis revealed a 3-fold increase of tyrosine hydroxylase gene expression after 5 days of incubation with ascorbic acid (200 microM), whereas expression of dopamine-beta-hydroxylase was found to be unaltered. In summary the data give evidence that ascorbic acid leads to enhanced DOPA production in SK-N-SH cells by two different mechanisms: at the metabolic level after short-term incubation and by increasing the tyrosine hydroxylase gene expression after long-term incubation. Based on these data we suppose that enhancement of DOPA synthesis by ascorbic acid may be useful in the treatment of early Parkinson's disease.

Ascorbic Acid↗
PubMed1998

Laparoscopic management of ovarian tumors.

BACKGROUND: Laparoscopy can be used with minimal operative morbidity to evaluate adnexal masses. We report our experience with the endoscopic approach to the diagnosis and treatment of ovarian tumors. In particular, we describe 11 patients who incidentally underwent laparoscopy and in whom the ovarian masses were found to be malignant. METHODS: Between September 1994 and September 1996, 292 patients with 316 ovarian tumors were treated laparoscopically in the Department of Obstetrics-Gynaecology, University of Ulm. We assessed vaginal ultrasonography, clinical assessment, the tumor marker CA 12-5, and the intraoperative low-power magnification for their value in predicting the final diagnosis in all laparoscopically treated ovarian tumors. RESULTS: From a total of 292 patients with ovarian tumors, 11 were diagnosed, intraoperatively or after final histologic examination, as having a malignant or borderline ovarian tumor. All applied pre- and intraoperative diagnostic procedures were by themselves too unreliable to exclude early stages of ovarian carcinoma exactly. CONCLUSIONS: On the basis of the present findings, we are tempted to conclude that laparoscopic surgery is justified in the management of ovarian tumors. Even with an accurate preoperative selection of suitable patients for laparoscopic surgery, the presence of an undetected ovarian carcinoma cannot be entirely excluded.

Adult↗
PubMed1997

Stress protein (hsp73)-mediated, TAP-independent processing of endogenous, truncated SV40 large T antigen for Db-restricted peptide presentation.

Transporter associated with antigen processing (TAP)-competent and TAP-deficient cell lines were transfected with expression plasmids encoding either the wild-type (wt) large tumor antigen (T-Ag) of SV40, or a truncated cytoplasmic variant (cT-Ag) of this viral protein. Stable expression of comparable levels of both forms of the viral protein was observed in different transfectants. The truncated cT-Ag variant, but not the wtT-Ag was stably associated with the constitutively expressed, cytosolic heat shock protein (hsp)73 chaperone. Two Db-binding peptides and one Kb-binding peptide of T-Ag were presented to cytotoxic T lymphocyte lines (CTLL) by TAP-competent transfectants expressing either wtT-Ag or cT-Ag. TAP-deficient transfectants expressing the wtT-Ag did not present any of these epitopes to CTLL. In contrast, TAP-deficient transfectants expressing the truncated hsp73-associated cT-Ag, presented the two Db-binding epitopes, but not the Kb-binding T-Ag epitope to CTLL. Regurgitation of peptides by transfectants was not detectable. The described data indicate that a pool of post-Golgi Db molecules is available for 2-3 h in TAP-deficient transfectants for loading with peptides released during endolysosomal processing of hsp73-associated, endogenous antigen.

Animals↗
PubMed1997

Targeting an anti-viral CD8+ T cell response to a growing tumor facilitates its rejection.

We demonstrate in a murine model that targeting an anti-viral T cell response to a growing tumor facilitates priming of a tumor-associated antigen (TAA)-specific, rejecting T cell response. Murine P815 mastocytoma cells grow aggressively in a syngeneic host. Transfected P815/S cells (expressing the hepatitis B surface antigen, HBsAg) also grow as subcutaneous tumors, but occasional 'spontaneous' rejections after transient growth are observed. Growth of P815/S tumors (but not of P815 tumors) is efficiently suppressed by a CD8+ cytotoxic T lymphocyte (CTL)-dependent immune mechanism in mice primed to HBsAg by DNA-immunization. In hosts immunized against HBsAg by DNA vaccination, HBsAg-specific CTL are generated. This specific CTL reactivity was targeted to s.c.-growing P815 tumors by intra tumor injections of either HBsAg-encoding plasmid DNA or viable P815/S cells; this treatment led to tumor rejection in 70-80% of the tumor-bearing animals. All rejecting animals showed a CD8+ CTL-dependent resistance to subsequent challenges by native, non-transfected P815 tumors. Targeting an established anti-viral ('strong') CTL response to a growing tumor hence is an efficient strategy to facilitate priming of a rejecting CTL response against ('weak') TAA in this system.

Animals↗
PubMed1996

DNA vaccination primes MHC class I-restricted, simian virus 40 large tumor antigen-specific CTL in H-2d mice that reject syngeneic tumors.

We investigated the stimulation of a MHC class I-restricted response of CTL to the SV40 large tumor Ag (T-Ag) by different vaccination strategies in H-2d and H-2b mice. Immunization with plasmid DNA or exogenous T-Ag, or infection with SV40, primed CTL to T-Ag in H-2b mice; these three different types of Ag delivery primed T-Ag-specific CTL populations with similar epitope/restriction specificities. In H-2d mice, i.m. immunization with plasmid DNA, but neither immunization with exogenous protein Ag nor SV40 infection, primed CTL to T-Ag. T-Ag-specific H-2d CTL were primed by DNA-based immunization in vivo, expressed the CD4-CD8+ phenotype, and were L(d)-restricted. In H-2d (DBA/2) mice, T-Ag-specific immune responses primed by plasmid DNA injection, but not those primed by exogenous T-Ag or SV40 infection, mediated CD8+ CTL-dependent rejection of T-Ag-expressing P815/T tumor grafts. The data indicate that immunization by plasmid DNA injection is an efficient strategy to induce class I-restricted CTL responses against oncogene-encoded Ags of low immunogenicity that mediate tumor rejection.

Amino Acid Sequence↗
PubMed1996

DNA vector constructs that prime hepatitis B surface antigen-specific cytotoxic T lymphocyte and antibody responses in mice after intramuscular injection.

We tested the efficiency of induction of immune responses to the small hepatitis B surface antigen (HBsAg) in mice by intramuscular DNA immunization using different vector constructs that allow high levels of HBsAg expression in mouse cells. The HBsAg-specific responses of class I-restricted cytotoxic T lymphocytes (CTL) and of B cells (serum antibody titers) were measured. Following the intramuscular inoculation of 'naked' DNA, five different vector constructs of 4-8 kb, that contained or did not contain an intron and/or the neo gene, in which HBsAg expression was driven by promoter sequences derived from the immediate early region of HCMV, the SV40 enhancer/promoter region, or a retroviral 3' LTR efficiently primed responses of class I-restricted CD8+ CTL precursors. In contrast, the constructs in which HBsAg expression was driven by HCMV-derived promoter sequences stimulated significantly higher levels of HBsAg-specific serum antibody titers after intramuscular DNA injection than the SV40 or MPSV vector constructs. Large (15 kb) episomal vector constructs did not stimulate CTL or antibody responses. The data demonstrate that: (i) intramuscular DNA immunization represents an efficient technique for priming CTL and antibody responses to HBsAg; (ii) many vectors can be constructed that express an immunogenic product after intramuscular inoculation of 'naked' DNA; (iii) the efficiency of the tested vector constructs to prime after DNA immunization, either a CTL response, or an antibody response, differs.

Animals↗
PubMed1996

Intraperitoneal regional chemotherapy with mitroxantrone.

Pharmacokinetic considerations and tests with cell lines and individual cell suspensions from metastatic human solid tumor biopsies suggested testing the efficacy of mitoxantrone (NOV) in intraperitoneal regional chemotherapy (IPRC). Twenty-seven patients with intraperitoneal metastatic disease of various solid tumors received cyclic IPRC with NOV for treatment of malignant ascites (N = 16) or of peritoneal carcinomatosis (N = 11) at a NOV instillate concentration of 10 micrograms/ml. A total of 125 cycles (1-5 per patient) were applied. Response and toxicity were registered according to WHO criteria. The response rate (CR+PR) was 56 percent in malignant ascites, 45 percent in peritoneal carcinomatosis, and 52 percent overall. There were no systemic toxicities. Regional side effects were bacteriemia (4 of 125 cycles), pain (2 of 125 cycles), small bowel stricture (1 of 27 patients), and small bowel perforation (1 of 27 patients). From these results we can conclude that NOV appears to be effective in IPRC for malignant ascites and peritoneal carcinomatosis at tolerable toxicities.

Antineoplastic Agents↗
PubMed1996

Virus-like particles induce MHC class I-restricted T-cell responses. Lessons learned from the hepatitis B small surface antigen.

H-2d mice generated a major histocompatibility complex (MHC) class I (Ld)-restricted T-cell response of defined restriction and epitope specificity to the hepatitis B virus small surface antigen (HBsAg). Here, we compare different vaccination techniques that prime in vivo class I-restricted, murine cytotoxic T lymphocyte (CTL) precursors and specific serum antibody responses. CTL were efficiently primed by the injection of low doses of recombinant native HBsAg particles without adjuvants, by the injection of low doses of denatured HBsAg monomers without adjuvants, by infection with recombinant vaccinia virus carrying a HBsAg-encoding gene, or by intramuscular transfer of plasmid DNA encoding HBsAg under appropriate promoter control. The observation that the injection of 100 ng to 1 microgram of native HBsAg "virus-like particles' (VLP) without adjuvants is an exogenous antigen preparation that efficiently primes class I-restricted CTL responses was unexpected. It reveals a novel aspect of the immunogenicity of VLP for T cells.

Animals↗
PubMed1995

Processing of exogenous heat-aggregated (denatured) and particulate (native) hepatitis B surface antigen for class I-restricted epitope presentation.

Many cell types efficiently present an epitope of the hepatitis B surface Ag (HBsAg) to murine class I-restricted CTL following an in vitro pulse with native 22-nm HBsAg particles. Processing of exogenous HBsAg particles required its cytochalasin B-insensitive uptake and acid proteolysis in an endocytic compartment, was insensitive to brefeldin A and cycloheximide, and did not involve regurgitation of antigenic peptides. In contrast, after an in vitro pulse of cells with exogenous, heat-denatured 1-micron HBsAg aggregates, only macrophages (but not other cell types tested) presented the Ld-restricted HBsAg epitope efficiently to CTL. Processing of exogenous HBsAg aggregates required its cytochalasin B-sensitive uptake, was insensitive to brefeldin A, and involved regurgitation of antigenic peptides. Processing of the two different, exogenous HBsAg preparations for class I-restricted epitope presentation thus involved alternative pathways: an "endocytic pathway" for native 22-nm particles, and a "phagocytic pathway" for denatured 1-microns aggregates. Both HBsAg preparations displayed different immunogenicity for class I-restricted CTL in vivo when delivered without adjuvants: native HBsAg particles were of high immunogenicity, and denatured HBsAg aggregates were of low immunogenicity. Class I-restricted CTL are thus primed in vivo after "endocytic processing" of native HBsAg particles as well as "phagocytic processing" of denatured HBsAg aggregates.

Animals↗
PubMed1995

Exogenous hepatitis B surface antigen particles processed by dendritic cells or macrophages prime murine MHC class I-restricted cytotoxic T lymphocytes in vivo.

Injection of low doses of particulate hepatitis B surface Ag (HBsAg) into H-2d mice without adjuvants primes an Ld-restricted, S28-39-specific T cell response. This study indicates that dendritic cells (DC) and macrophages (M phi) both serve as APCs that support priming of CD8+ CTL precursors in vivo to exogenous HBsAg particles. After transfer into a syngeneic, naive host, HBsAg particle-pulsed DC, either freshly purified from skin or derived from a cloned DC line, efficiently primed class I-restricted, HBsAg-specific CTL precursors. M phi, either harvested from the peritoneal cavity or generated in macrophage-CSF-stimulated bone marrow cell cultures in vitro or derived from established, cloned M phi lines (PU5-1.8, J774A.1), pulsed with HBsAg particles in vivo or in vitro, elicited a class I-restricted, HBsAg-specific CTL response after adoptive transfer into naive hosts. The class I-restricted CTL response induced by HBsAg particle immunization was suppressed in carrageenan-treated mice, but was restored when carrageenan-treated mice were immunized with syngeneic, HBsAg-pulsed M phi. Selective elimination of M phi by liposome-incorporated dichloromethylene-diphosphonat did not suppress the induction of a CTL response of H-2d mice by HBsAg particle immunization. HBsAg-pulsed, freshly prepared DC are more potent than pulsed M phi in priming class I-restricted CTL in vivo. The relative importance of both types of APC in priming CTL remains to be resolved.

Animals↗
PubMed1995

Nucleic acid vaccination primes hepatitis B virus surface antigen-specific cytotoxic T lymphocytes in nonresponder mice.

The efficiency of different vaccination techniques to prime in vivo major histocompatibility complex class I-restricted murine cytotoxic T-lymphocyte (CTL) precursors to hepatitis B virus small surface antigen (HBsAg) was investigated. Mice were immunized either by injection of a low dose of recombinant HBsAg protein preparations (native HBsAg particles or denatured HBsAg monomers) without adjuvants, by infection with recombinant vaccinia virus carrying an HBsAg-encoding gene, or by intramuscular transfer of plasmid DNA encoding HBsAg under appropriate promoter control. In H-2d mice, an Ld-restricted, S28-39-specific CTL response was efficiently primed by all alternative vaccination techniques tested, but the most potent priming of class I-restricted CTL to HBsAg in vivo was observed with DNA immunization. Priming of anti-HBsAg CTL in H-2b mice was not detectable after infection with a recombinant vaccinia virus or after injection with exogenous recombinant HBsAg preparations. After DNA immunization, however, both Kb- and Db-restricted CTL reactivity to HBsAg emerged in H-2b mice. Hence, nucleic acid immunization revealed class I-restricted CTL responsiveness to HBsAg in a mouse strain previously considered to be a nonresponder at the CTL level. These results demonstrate that the simple technique of nucleic acid immunization not only is extremely efficient but also reveals an extended spectrum of potentially immunogenic epitopes of protein antigens.

Animals↗