Biomedical subjects

W Meier

Publications and source records attributed to W Meier.

At least 55 records · Page 3Linked to original sources

PubMed1997

Characterization of lymphotoxin-alpha beta complexes on the surface of mouse lymphocytes.

The lymphotoxin-alpha beta complex (LT alpha beta) is found on the surface of activated lymphocytes and binds to a specific receptor called the LT beta receptor (LT beta R). In the mouse, signaling through this pathway is important for lymph node development and splenic organization, yet the biochemical properties of murine LT alpha and LT beta are essentially unknown. Here we have used soluble receptor-Ig forms of LT beta R and TNF-R55 and mAbs specific for murine LT alpha, LT beta, and LT beta R to characterize the appearance of surface LT alpha beta complexes and LT beta R on several common murine cell lines. Cells that bound LT beta R also bound anti-LT alpha and anti-LT beta mAbs in a FACS analysis. The ability of these reagents to discriminate between surface TNF and LT was verified by analysis of surface TNF-positive, LPS-activated murine RAW 264.7 monocytic cells. Primary mouse leukocytes from spleen, thymus, lymph node, and peritoneum were activated in vitro, and CD4+ and CD8+ T cells as well as B cells expressed surface LT ligand but not the LT beta R. Conversely, elicited peritoneal monocytes/macrophages were surface LT negative yet LT beta R positive. This study shows that on mononuclear cells, surface LT complexes and receptor are expressed similarly in mice and man, and the tools described herein form the foundation for study of the functional roles of the LT system in the mouse.

Animals↗

PubMed1997

Cytotoxic activities of recombinant soluble murine lymphotoxin-alpha and lymphotoxin-alpha beta complexes.

Human lymphotoxin-alpha (LT alpha) is found in a secreted form and on the surface of lymphocytes as a complex with a second related protein called lymphotoxin-beta (LT beta). Both secreted human LT alpha and TNF have similar biological activities mediated via the TNF receptors, whereas the cell surface LT alpha beta complex binds to a separate receptor called the LT beta receptor (LT beta R). The murine LT alpha and LT beta (mLT alpha and mLT beta) proteins have never been characterized. When recombinant mLT alpha was produced by either of several methods, the protein had a very low specific activity relative to that of human LT alpha in the conventional WEHI 164 cytotoxicity bioassay. The weak activity observed was inhibited by a soluble murine TNF-R55 Ig fusion protein (mTNF-R55-Ig), but not by mLT beta R-Ig. Coexpression of both mLT alpha and a soluble version of mLT beta in insect cells led to an LT alpha beta form that was cytotoxic in the WEHI 164 assay via the LT beta R. To determine whether natural mLT alpha-like forms with cytotoxic activity comparable to that of secreted human LT alpha were secreted from primary spleen cells, splenic lymphocytes were activated in various ways, and their supernatants were analyzed for cytotoxic activity. Using specific Abs to distinguish between mTNF and mLT, a TNF component was readily detected; however, there was no evidence for a secreted mLT alpha cytotoxic activity using this assay. Combined, these observations suggest that secreted mLT alpha may not play a role in the mouse via interactions with TNF-R55, and the ramifications of this hypothesis are discussed.

Amino Acid Sequence↗

PubMed1997

CNS late effects after ALL therapy in childhood. Part I: Neuroradiological findings in long-term survivors of childhood ALL--an evaluation of the interferences between morphology and neuropsychological performance. The German Late Effects Working Group.

The effect of cranial irradiation on possible therapy-induced morphological central nervous system (CNS) side effects of children cured from acute lymphoblastic leukemia (ALL) is controversially discussed. In a retrospective multicenter study, 118 former ALL patients in first continuous remission were investigated using cranial computerised tomography (CCT) or magnetic resonance imaging (MRI) scans to evaluate CNS related impairments. Corresponding to the different kinds of CNS prophylaxis, the patient sample was divided: group A (n = 39) receiving intrathecal methotrexate (ITMTX) and systemical medium-high-dose methotrexate (SMHDMTX), group B (n = 41) cranial irradiated (in mean 16.8 Gy) and administering ITMTX and SMHDMTX, group C (n = 38) irradiated (in mean 17.1 Gy) and getting ITMTX. Pathologic scans showed atrophy, leukoencephalopathy, calcifications or grey matter changes. These findings were compared with the neuropsychological test results. Abnormal MRI or CCI scans were found in 61/118 patients (51.7%). Fifteen belonged to group A (38.5%), 23 to B (56.1%) and 23 to C (60.5%). Patients with definite CNS changes show reduced neuropsychological test results. The prevalence of brain alterations seems to appear twice increased after lengthening the posttherapeutic interval in irradiated patients as in nonirradiated patients. Irradiated patients as an age younger than 2 years at diagnosis may show a lower prevalence for developing CNS alterations. CNS alterations are not sex-related. Children treated with cranial irradiation in combination with SMHDMTX and/or ITMTX were at greater risk of developing morphological brain alterations than patients with chemotherapy alone. These alterations are partly correlated with reduced neuropsychological performances and seem to stay with a longer posttherapeutic interval.

Adolescent↗

PubMed1997

CNS late effects after ALL therapy in childhood. Part II: Conventional EEG recordings in asymptomatic long-term survivors of childhood ALL--an evaluation of the interferences between neurophysiology, neurology, psychology, and CNS morphology. German Late Effects Working Group.

Monitoring of therapy-related late effects after acute lymphoblastic leukemia (ALL) therapy in childhood has become an increasingly important area in posttherapeutic patient surveillance. The usefulness of conventional electro-encephalographic (EEG) investigations as part of these attempts is controversially discussed. However, EEG recordings have become a popular approach for judgement on the functional integrity of the central nervous system in this subject group. The present report focuses on this problem and discusses the question whether and to what extent conventional EEG recordings were correlated with further measures of central nervous system (CNS) integrity and therapeutic differences. EEGs were recorded in 110 subjects, asymptomatic long-term survivors of ALL in childhood, during a large retrospective multicenter study evaluating CNS late sequelae following antileukemic therapy in Germany and Austria. EEG findings were correlated with demographic data, illness- and treatment-related parameters, as well as with data on the morphological, neurological and psychological status of the participating subjects. At the time of follow-up the EEG was abnormal in 47 cases (42.7%). The most frequent EEG abnormalities observed were disturbances of the background activity (n = 45, 95.8%), followed by hypersynchrone activities (n = 1.0, 21.3%) and interhemispheric differences/focal slowing (n = 6, 12.8%). With exception of age at diagnosis, none of the observed EEG abnormalities showed a correlation with any of the aforementioned illness- or treatment-related parameters. Eighty percent of the observed EEG abnormalities were found in children younger than 5 years at diagnosis. Children less than 2 years of age as well as those above 5 years at onset of disease showed a significantly reduced prevalence of EEG disturbances compared to subjects between 2 and 5 years at diagnosis. Neither the degree of illness nor therapy-specific differences showed any relationship to EEG outcome. There was no specific EEG finding for a specific morphological substrate, neurological or psychological deficiency and vice versa. Overall, there was no beneficial effect of routine EEG testing in children following therapy for ALL. According to our data, the evaluation of conventional EEG recordings of otherwise asymptomatic ALL long-term survivors is not a very helpful measure for predicting the degree of behavioral deficiencies, neurological disturbances, or morphological CNS abnormalities, which may be present or will develop in this special subject group.

Adolescent↗

PubMed1997

Neurophysiological findings in long-term survivors of acute lymphoblastic leukaemia in childhood treated with the BFM protocol 81 SR-A/B.

UNLABELLED: Monitoring of therapy-related late effects after acute lymphoblastic leukaemia (ALL) therapy in childhood has become an increasingly important field in posttherapeutic patient surveillance. The usefulness of neurophysiological investigations (e.g. EEG, evoked potentials (EP)) as part of these attempts is controversial. The present report focuses on this problem and the question whether and to what extent routinely performed EEG recordings and visual evoked potentials (VEP) were correlated with further measures of CNS integrity. EEGs and VEPs were recorded in 163 asymptomatic long-term survivors of ALL in childhood during a large retrospective multicentre study evaluating CNS late sequelae following antileukaemic therapy. Fifty-two ALL long-term survivors (4.5-10.6 years after end of therapy, median: 8.8 years), who had been treated according to BFM-81 SR-A (n = 30) or SR-B (n = 22) were selected for this analysis focusing on therapy-related CNS late effects. Therapy protocols differed with regard to the mode for CNS prophylaxis: SR-A, cranial irradiation with intrathecal methotrexate; SR-B, intrathecal and iv methotrexate. Neurophysiological findings were correlated with illness- and treatment-related parameters, as well as with data on the morphological, neurological and psychological status of the CNS. At the time of follow-up neurophysiological measures were abnormal in 28/52 cases (53.8%). Neither illness- nor therapy-specific differences in CNS prophylaxis showed any relationship to EEG/VEP outcome any relationship to EEG/VEP outcome in this reduced group of the whole study population. Children with EEG/VEP abnormalities showed a significantly higher incidence of structural CNS disturbances compared to those with inconspicuous neurophysiological recordings (60.9% vs 31.8%). However, in this special subject group there was no specific neurophysiological finding for a specific morphological substrate, neurological or psychological deficiency and vice versa. CONCLUSION: Routinely performed EEG/VEP investigations are not very helpful measures to predict the presence or degree of behavioural deficiencies, neurological disturbances, or morphological CNS abnormalities. Patients who received cranial irradiation or systemic methotrexate applications showed the same incidence of neurophysiological disturbances without evidence for specific neurotoxic correlates.

Adolescent↗

PubMed1997

Lesions associated with infectious keratoconjunctivitis in alpine ibex.

Following a severe infectious keratoconjunctivitis (IKC) epizootic in free-ranging alpine ibex (Capra ibex ibex) in Switzerland in 1993, 19 animals were examined from six different populations. Mucopurulent exudates, reddened conjunctiva and mononuclear inflammatory cell infiltration in the conjunctiva and the limbic area were observed in mild cases. In more severe cases, lesions ranged from perilimbic neovascularization to corneal edema, erosion, ulceration and neovascularization accompanied by infiltration of neutrophils. Sometimes an iridocyclitis was observed. In the most advanced stages, the cornea was perforated and an anterior synechia was present. Lesions found in ibex affected with IKC indicated a non-generalized, specific ocular disease. The other organs investigated did not show alterations suggestive of changes induced by agents which might cause IKC, including Chlamydia spp. and Mycoplasma. spp. The microbiological findings indicate that Mycoplasma conjunctivae is the primary pathogenic agent causing IKC in this species in Switzerland.

Animals↗

PubMed1997

Interphase cytogenetic analysis of mucinous ovarian neoplasms.

Extending our previous efforts to characterize ovarian neoplasms by interphase cytogenetics, we analyzed a series of 32 mucinous tumors by nonisotopic in situ hybridization with seven different centromere-specific probes as well as by flow and image DNA cytometry; we then compared the data with results of p53 and Ki67 immunohistochemistry and MYC DNA-PCR analysis and of the clinical follow-ups. Of the tumors studied, 11 of 14 (78.6%) mucinous carcinomas, 7 of 7 (100%) mucinous tumors of low malignant potential (LMP), and 7 of 11 (63.6%) mucinous cystadenomas demonstrated chromosomal aberrations. The mean number of chromosomal aberrations (+/- SD) was slightly higher in DNA cytometrically nondiploid cases than in diploid cases (2.0 +/- 1.6 versus 1.6 +/- 1.2, not significant) but did not differ significantly among the study groups (carcinomas: 1.7 +/- 1.4; tumors of LMP; 1.9 +/- 0.7; adenomas: 1.4 +/- 1.4). Aberrations affected chromosomes 1 (14 of 27 cases) and 6 (12 of 31) most frequently, followed by chromosomes 17 (7 of 28), 7 (6 of 29), and X (6 of 28). Signal gain for centromere 1, which was the most prevalent finding (13 of 27), was observed in 3 of 10 mucinous cystadenomas, 2 of 4 mucinous tumors of LMP, and 8 of 13 mucinous carcinomas. All six moderately and poorly differentiated carcinomas demonstrated this aberration. Signal gain of centromere 6 (3 of 13) and centromere 7 (4 of 13) were found only in carcinomas (p < 0.05 and p < 0.025, respectively). The interphase cytogenetic results correlated neither with proliferative activity, immunohistochemical p53 accumulation, MYC DNA amplification, nor postoperative outcome. Compared with serous ovarian neoplasms (Lab Invest 1996, 75:473-485), mucinous tumors demonstrated signal gain for chromosome 1 (p < 0.0001) and signal loss for chromosomes 6 (p < 0.001) and X (p < 0.01) significantly more often. Loss of centromere 17 was more characteristic for serous than for mucinous carcinomas (p < 0.05). Our observations show that chromosomal aberrations in mucinous ovarian neoplasms are apparently not random. These results support the notion that the molecular genetic changes in mucinous neoplasms differ from those in serous tumors.

Adenocarcinoma, Mucinous↗

PubMed1997

Carboplatin plus paclitaxel as first-line chemotherapy in previously untreated advanced ovarian cancer. German AGO Study Group Ovarian Cancer. Arbeitsgemeinschaft Gynäkologische Onkologie.

Since publication of the results of the Gynecologic Oncology Group (GOG) III study, the combination of cisplatin and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has been adopted widely as the new standard for treating advanced ovarian cancer. Further attempts to optimize first-line chemotherapy with platinum and taxanes include substituting carboplatin for cisplatin, individualizing the carboplatin dose by calculating it according to the area under the concentration-time curve, and reducing the length of the paclitaxel infusion. Attempts to optimize platinum/paclitaxel combinations have led to the initiation of several small phase I/II trials evaluating the carboplatin/paclitaxel combination. The promising results of these studies have prompted the initiation of three phase III trials comparing carboplatin/paclitaxel with the standard combination of cisplatin/paclitaxel. An interim analysis after 1 year's accrual to the prospectively randomized German Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) study is presented. Treatment consists of paclitaxel 185 mg/m2 infused over 3 hours on day 1 followed directly by either cisplatin 75 mg/m2 (arm B) or carboplatin dosed to an area under the curve of 6 (arm A). Treatment is repeated every 3 weeks for six courses. Eligibility criteria are epithelial ovarian cancer International Federation of Gynecology and Obstetrics stage IIB through IV, age of consent, written informed consent, Eastern Cooperative Oncology Group performance status < or =2, life expectancy of more than 12 weeks, adequate bone marrow function defined as neutrophil count 1.5 x 10(9)/L and platelet count > or =100 x 10(9)/L, adequate renal function defined as glomerular filtration rate (GFR) > or =60 mL/min, and adequate liver function defined as serum bilirubin levels within 1.25 x upper limit of normal. From October 1995 to December 1996, 442 of 660 planned patients were recruited to the AGO study. The interim analysis is based on data from 353 patients who were enrolled within the first study year. These preliminary data indicate that hematologic toxicity occurred more frequently in arm A (carboplatin/paclitaxel), while nonhematologic toxicity occurred slightly more frequently in arm B. Dose-intensity analysis did not reveal cumulative dose reductions or increasing use of colony-stimulating factors over subsequent courses in either arm. In all, 44 patients with measurable disease following surgery completed chemotherapy and were evaluable for response. The data remain blinded at this time, and results are reported for the group as a whole. So far, there have been 18 (41%) complete responses and 15 (34%) partial responses, for an overall response rate of 75%. Retrospective comparison with the GOG results reveals no significant difference in response rates between patients in the cisplatin/paclitaxel arm of GOG III and those in the AGO study: the GOG study reported a 73% response rate, compared with a preliminary 75% response rate in the AGO study, resulting in a relative risk of 1.03 (95% confidence interval, 0.83 to 1.27). Overall, this interim analysis did not reveal any reason to terminate this study early. Accrual is ongoing and is expected to be completed in 1997.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Carboplatin/paclitaxel versus cisplatin/paclitaxel as first-line chemotherapy in advanced ovarian cancer: an interim analysis of a randomized phase III trial of the Arbeitsgemeinschaft Gynäkologische Onkologie Ovarian Cancer Study Group.

Since publication of the results of the Gynecologic Oncology Group III study, the combination of cisplatin/paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has been widely adopted as standard treatment for advanced ovarian cancer. Further attempts to optimize first-line chemotherapy with platinum and taxanes include the substitution of cisplatin with carboplatin, individualization of the carboplatin dose by calculating it according to the area under the concentration-time curve, and reduction of paclitaxel infusion duration. These attempts have led to the initiation of several phase I/II trials evaluating the combination of carboplatin/paclitaxel. The promising results of these small studies have prompted the initiation of three phase III trials comparing carboplatin/paclitaxel with the standard combination of cisplatin/paclitaxel. The interim analysis after 15 months' accrual of the prospectively randomized German Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) study is presented here. As of January 1997, 518 of 660 planned patients have been recruited. The interim analysis is based on data from 449 evaluable patients. The preliminary data indicate that hematologic toxicity occurred more frequently in arm A (carboplatin/paclitaxel), whereas nonhematologic toxicity occurred slightly more frequently in arm B (cisplatin/paclitaxel). Dose-intensity analysis did not reveal cumulative dose reductions or an increased need for colony-stimulating factors over subsequent courses in both arms. Forty-four patients with measurable disease following surgery completed chemotherapy and were evaluable for response, which remains blinded at this time and is reported for the group as a whole. So far, there have been 18 complete responses (41%) and 15 partial responses (34%), for an overall response rate of 75%. Retrospective comparison reveals no significant difference in response rates between patients in the cisplatin/paclitaxel arm of Gynecologic Oncology Group III and those in the Arbeitsgemeinschaft Gynäkologische Onkologie study. Overall, this interim analysis did not reveal any reason for an early termination of this study. Accrual is ongoing and is expected to be completed this year.

Antineoplastic Agents↗

PubMed1996

Clinical significance of the tumour markers CA 125 II and CA 72-4 in ovarian carcinoma.

In a retrospective study we compared the usefulness of the tumour marker CA 72-4 with the established marker CA 125 II (both EIA on Cobas-Core, Hoffmann LaRoche, Basel Switzerland) at the time of primary diagnosis of ovarian carcinoma (n = 123) in order to discriminate between ovarian carcinomas of different histological type. We compared their diagnostic value, behaviour in follow-up care and evaluated possible combinations. Fixing specificity at 95% vs. benign gynaecological diseases (n = 37) as the clinically relevant reference group, we found cut-off values of 160 U/mL for CA 125 II and 3.0 U/mL for CA 72-4. On the basis of this specificity, we found comparable sensitivity for CA 125 II and CA 72-4 for all kinds of ovarian carcinoma at the time of primary diagnosis. With regard to histology, we found best sensitivity for CA 125 II in serous ovarian cancer and for CA 72-4 in mucinous ovarian cancer. Additional sensitivities were found in ovarian carcinoma in general but little in serous ones. No additive sensitivity was found in mucinous ovarian carcinomas with CA 72-4 as leading marker. In follow-up care, CA 72-4 was the leading marker in II cases and CA 125 II in 16, while in one case both markers were negative. In 6 cases the change of values reflecting clinical follow-up-care was within the so-called reference range. According to our results, at the time of primary diagnosis because of lack of histological findings the combined determination of CA 125 II and CA 72-4 can be recommended. In follow-up care and control of efficacy of therapy the preoperative positive or leading marker is generally sufficient. The determination of both markers in follow-up care is indicated only if they both are negative at primary diagnosis and until one of them becomes clearly positive.

Adenocarcinoma, Mucinous↗

PubMed1996

Preparation and characterization of soluble recombinant heterotrimeric complexes of human lymphotoxins alpha and beta.

The lymphotoxin (LT) protein complex is a heteromer of alpha (LT-alpha, also called tumor necrosis factor (TNF)-beta) and beta (LT-beta) chains anchored to the membrane surface by the transmembrane domain of the LT-beta portion. Both proteins belong to the TNF family of ligands and receptors that regulate aspects of the immune and inflammatory systems. The LT complex is found on activated lymphocytes and binds to the lymphotoxin-beta receptor, which is generally present on nonlymphoid cells. The signaling function of this receptor-ligand pair is not precisely known but is believed to be involved in the development of the peripheral lymphoid organs. To analyze the properties of this complex, a soluble, biologically active form of the surface complex was desired. The LT-beta molecule was engineered into a secreted form and co-expressed with LT-alpha using baculovirus/insect cell technology. By exploiting receptor affinity columns, the LT-alpha3, LT-alpha2/beta1, and LT-alpha1/beta2 forms were purified. All three molecules were trimers, and their biochemical properties are described. The level of LT-alpha3-like components in the LT-alpha1/beta2 preparation was found to be 0.02% by following the activity of the preparation in a WEHI 164 cytotoxicity assay. LT-alpha3 with an asparagine 50 mutation (D50N) cannot bind the TNF receptors. Heteromeric LT complexes were prepared with this mutant LT- alpha form, allowing a precise delineation of the extent of biological activity mediated by the TNF receptors. A LT-alpha3 based cytotoxic activity was used to show that the LT-alpha1/beta2 form cannot readily scramble into a mixture of forms following various treatments and storage periods. This biochemical characterization of the LT heteromeric ligands and the demonstration of their stability provides a solid foundation for both biological studies and an analysis of the specificity of the LT-bet a and TNF receptors for the various LT forms.

Amino Acid Sequence↗

PubMed1996

Signaling through the lymphotoxin beta receptor induces the death of some adenocarcinoma tumor lines.

Surface lymphotoxin (LT) is a heteromeric complex of LT-alpha and LT-beta chains that binds to the LT-beta receptor (LT-beta-R), a member of the tumor necrosis factor (TNF) family of receptors. The biological function of this receptor-ligand system is poorly characterized. Since signaling through other members of this receptor family can induce cell death, e.g., the TNF and Fas receptors, it is important to determine if similar signaling events can be communicated via the LT-beta-R. A soluble form of the surface complex was produced by coexpression of LT-alpha and a converted form of LT-beta wherein the normally type II LT-beta membrane protein was changed to a type I secreted form. Recombinant LT-alpha 1/beta 2 was cytotoxic to the human adenocarcinoma cell lines HT-29, WiDr, MDA-MB-468, and HT-3 when added with the synergizing agent interferon (IFN) gamma. When immobilized on a plastic surface, anti-LT-beta-R monoclonal antibodies (mAbs) induced the death of these cells, demonstrating direct signaling via the LT-beta-R. Anti-LT-beta-R mAbs were also identified that inhibited ligand-induced cell death, whereas others were found to potentiate the activity of the ligand when added in solution. The human WiDr adenocarcinoma line forms solid tumors in immunocompromised mice, and treatment with an anti-LT-beta-R antibody combined with human IFN-gamma arrested tumor growth. The delineation of a biological signaling event mediated by the LT-beta-R opens a window for further studies on its immunological role, and furthermore, activation of the LT-beta-R may have an application in tumor therapy.

Adenocarcinoma↗

PubMed1996

Short course single agent therapy with an LFA-3-IgG1 fusion protein prolongs primate cardiac allograft survival.

The interaction of T cell costimulatory molecules with their ligands is required for optimal T cell activation. Interference with such interactions can induce antigen unresponsiveness and delay xeno- and allograft rejection. We have previously shown that LFA3TIP, a soluble human lymphocyte function-associated antigen (LFA)-3 construct, binds CD2 and inhibits responses of human T cells in vitro. This study reports the first use of a human fusion protein, LFA3TIP, to significantly prolong primate cardiac allograft survival. Based on our observations that LFA3TIP inhibits baboon allogeneic mixed lymphocyte reactions, we gave baboon recipients of heterotopic cardiac allografts injections of LFA3TIP, 3 mg/kg i.v., for 12 consecutive days, starting 2 days before transplantation. This regimen delayed graft rejection from an average of 10.6 +/- 2.3 days for human IgG-treated controls (n = 5) to an average of 18.0 +/- 5.3 days for LFA3TIP-injected animals (n = 7; P < or = 0.01). Grafts from LFA3TIP-treated animals showed markedly diminished coronary endothelialitis as compared with control animals. LFA3TIP reached peak serum levels of approximately 100 micrograms/ml after 7-9 injections and persisted in the 10-micrograms/ml range for 1 to 2 weeks after the final injection. Despite these blood levels, circulating antibodies to LFA3TIP were not detected in the serum. No renal or hepatic toxicity was noted. The possible mechanism by which LFA3TIP acts to inhibit graft rejection is discussed; success in prolonging graft survival when LFA3TIP is used as a single-agent therapy suggests great potential for this novel therapeutic agent.

Animals↗

PubMed1996

Interfacial charge transport in water-in-oil microemulsions stabilized by ionic-non-ionic surfactant mixtures.

Interfacial charge transport and mobility have been studied in system-spanning nanodroplet clusters formed in water-in-oil microemulsions stabilized by non-ionic-ionic surfactant mixtures. An unexpectedly large reduction in the counterion mobility was derived from a two-step adsorption process which described the Langmuir-plot-like conductivity isotherm remarkably well. It also conformed very satisfactorily to mobility data of the sodium bis-2-ethylhexylsulfosuccinate (AOT) counterion derived from frequency-dependent dielectric dispersion measurements with singly dispersed nanodroplets of the same system as used with the cluster studies. The activation energy attributed to the counterion mobility allowed one to calculate approximately the minimum distance between the (positive) counterion in the bulk and the surfactant anion in the interface.

Journal Article↗

PubMed1996

DNA ploidy and MYC DNA amplification in ovarian carcinomas. Correlation with p53 and bcl-2 expression, proliferative activity and prognosis.

There is increasing evidence that DNA ploidy is a prognostic factor in ovarian carcinomas, but it is uncertain whether MYC DNA amplification is an epiphenomenon of DNA nondiploidy or a distinct biological change with an impact on the clinical course of the disease. To clarify these issues we analysed DNA ploidy by flow and image cytometry and MYC copy number by polymerase chain reaction in archival material from ovarian carcinomas with known follow up. The results were compared with proliferative activity (Ki67 index) and p53 and bcl-2 expression. DNA cytometry revealed nondiploidy in 84 of 144 cases (58.3%). Nondiploidy was statistically significantly correlated with histological tumour type, histological grade, Ki67 index > 10%, FIGO stage, presence of residual tumour after debulking surgery and adverse postoperative outcome. Furthermore, DNA nondiploidy was associated with p53 accumulation. We found that 84.9% of the p53-positive cases were nondiploid. This points to the paramount importance of wild type p53 for the maintenance of genome integrity in this tumour type. MYC DNA amplification was seen in 33.8% (26/77 cases) of ovarian carcinoma. There was no correlation between MYC DNA amplification and histological tumour type, histological grade, FIGO stage, DNA ploidy, proliferative activity or prognosis. However, when p53 and bcl-2 expression was taken into account, a statistically significant correlation between gene alteration or expression patterns and histological tumour type was revealed. The group of mucinous carcinomas demonstrated both MYC DNA amplification and strong bcl-2 expression in 50% and contained the largest fraction of cases without aberration (37.5%). Endometrioid carcinomas were characterized by strong bcl-2 expression in 85%, whereas serous and undifferentiated carcinomas predominantly exhibited p53 alterations, frequently accompanied by bcl-2 overexpression or MYC DNA amplification. Thus, in interaction with other genes MYC DNA amplification may play a role in the determination of the varying differentiation patterns of ovarian carcinomas.

Aged↗

PubMed1996

Quantitative EEG in long-term survivors of acute lymphoblastic leukemia.

Conventional and quantitative aspects of electroencephalographic recordings obtained during a follow-up surveillance study in long-term survivors of acute lymphoblastic leukemia in childhood were investigated with respect to differences in central nervous system prophylaxis given during antileukemic therapy and compared with data derived from healthy controls. Central nervous system prophylaxis consisted either of cranial irradiation (18 Gray, group A, n = 8) or intermediate high-dose methotrexate (2000 mg/m2; group B, n = 5), each combined with intrathecal methotrexate. Conventional electroencephalographic analysis revealed comparable results in all three study groups. However, quantitative electroencephalography showed significantly increased absolute power scores for all frequency bands in both long-term survivor groups. Relative power estimates revealed a significant increase in delta/tau activities in both prophylaxis groups compared to healthy controls, which were countered by decreased percentage power scores in the alpha-range. Quantitative electroencephalographic comparisons between both central nervous system prophylaxis groups revealed only small differences in quantity, not quality, of the observed power disturbances with slightly higher deviations in irradiated long-term survivors than in nonirradiated ones. Topographical distributions of spectral band power were comparable between all three study groups without evidence for therapy-related topographical differences.

Adolescent↗

PubMed1996

[13-cis retinoic acid and interferon-alfa-2a as palliative therapy in pretreated, recurrent squamous epithelial carcinoma of the cervix uteri and vulva].

Patients with metastasising carcinoma of the uterine cervix or recurrent disease, in whom local treatment as surgery or radiotherapy has failed, are still an unsolved problem. Platinum-based multi-agent chemotherapies achieve overall response rates up to 60%, but side effects are serious and so far no survival benefit has been proven. Recent publications report on a synergistic effect of combination therapy using 13-cis-retinoic acid and interferon alpha-2 a in the treatment of squamous cell carcinoma of the cervix. In a pilot study we include 6 patients with locally recurrent or metastasising squamous cell carcinomas, five of the uterine cervix, one of the vulva. The systemic therapy consisted of-orally administered 13-cis-retinoic acid (80 mg q. d.) and subcutaneously injected interferon alpha-2 a (6 x 10(6) I.E. q. d.). All patients were primarily treated by surgical and/or radiation therapy. In each case chemotherapy had been either already performed or rejected by the patient. Median duration of treatment was 52 days, median survival time 107 days. Out of 6 patients 3 experienced progression of disease uninfluenced by therapy. One patient with multiple subcutaneous lymph node metastases showed mixed response for a short period of 3 weeks before progression and eventual death. One patient had no change or disease for 13 months with subsequent progression and eventual death after 22 months. One patient could not be evaluated for an allergic reaction after only 15 days of treatment. Other side effects were "flu-like symptoms", skin irritations, conjunctivitis sicca and chileitis, all WHO 1-2. Overall toxicity must be rated low compared to standard chemotherapy, but is not negligible. In our study the positive reports in literature concerning the treatment of primary advanced cervical cancer and recurrent advanced carcinoma of the skin could not be reproduced. This might be due to the small number of cases, which is a common problem in immunotherapeutic studies. Moreover, very unfavourable patient selection criteria in our study compared to primarily untreated patients may also have contributed to different response rates. However, in our opinion the tested regimen cannot be considered sufficiently effective in patients suffering from pretreated, recurrent squamous cell carcinoma of the cervix or vulva.

Administration, Oral↗

PubMed1996

P300 abnormalities in long-time survivors of acute lymphoblastic leukemia in childhood--side effects of CNS prophylaxis?

The incidence and the degree of P300 abnormalities in relation to psychometric findings was assessed in two groups of long-term survivors of acute lymphoblastic leukemia (ALL) in childhood. The study was performed as part of a follow-up trial, evaluating CNS late-effects after antileukemic therapy, 7.1 +/- 1.6 years after cessation of antileukemic therapy. Subject groups differed primarily in terms of antileukemic CNS prophylaxis: combined radio- and chemotherapy (n = 8) vs. chemotherapy alone (n = 5). Results were compared with those of a third group of healthy controls (n = 13) matched for age and gender. P300 recordings were obtained during a visual oddball-paradigm using checkerboard reversal stimuli of different pattern sizes as target and background events. Neurophysiological data were correlated with the results of a psychological test battery, which measured general intelligence, non-verbal visual memory functioning and concentration. ERP analysis showed a significant prolongation of the P300 latency in irradiated subjects when compared to healthy controls and non-irradiated long-term survivors. Topographical data comparisons revealed substantial P300 differences in both ALL long-term survivor groups when compared with healthy controls. This demonstrated significantly lower amplitudes over the left frontal derivations, associated with lowered concentration abilities, in the irradiated subject group. Higher amplitudes over the parieto-temporal derivations of the right hemisphere, associated with significantly impaired visual memory capabilities, were seen in both long-term survivor groups.

Adolescent↗