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M Schmidt

Publications and source records attributed to M Schmidt.

At least 163 records · Page 9Linked to original sources
PubMed2001

Synergistic interaction between an anti-p185HER-2 pseudomonas exotoxin fusion protein [scFv(FRP5)-ETA] and ionizing radiation for inhibiting growth of ovarian cancer cells that overexpress HER-2.

OBJECTIVES: The HER-2 proto-oncogene is overexpressed in 15-30% of ovarian cancers, providing a target for therapy in a fraction of patients. We previously described the ability of a recombinant single-chain anti-p185HER-2-Pseudomonas exotoxin A fusion protein, scFv(FRP5)-ETA, to inhibit growth of cancer cells in culture and tumor xenografts in vivo. We have also described synergistic interaction between an anti-p185HER-2-ricin A chain immunotoxin and ionizing radiation for inhibiting growth of ovarian and breast cancer cells that overexpress HER-2. Our objective in this report was to evaluate the in vitro and in vivo effects of scFv(FRP5)-ETA against SKOv3 ovarian cancer cells that have been transfected to express >10(6) p185HER-2 receptors per cell (clone-9002-18). METHODS: Inhibition of clonogenic growth was measured in vitro by limiting dilution analysis. Inhibition of tumor growth was measured in vivo using heterografts established with the same ovarian cancer cell lines. RESULTS: Clone-9002-18 cells were substantially more sensitive than parental SKOv3 cells to the cytotoxic effects of scFv(FRP5)-ETA. Exotoxin fusion protein induced apoptosis in clone-9002-18 cells, but did not affect parental SKOv3 cells. Treatment of clone-9002-18 cells with 200- to 2000-cGy external beam irradiation in combination with scFv(FRP5)-ETA produced synergistic elimination of clonogenic tumor cells in culture. In vivo, subcutaneous or intraperitoneal growth of tumor xenografts in nu/nu mice was significantly inhibited (P = 0.004) by treatment for 10 days with scFv(FRP5)-ETA or with 131I-labeled-520C9 anti-p185HER-2 radionuclide conjugate, but additive effects were not observed with combined treatment. CONCLUSION: ScFv(FRP5)-ETA deserves further evaluation for intraperitoneal therapy of ovarian cancers that overexpress p185HER-2.

ADP Ribose Transferases↗
PubMed2001

Novel technique to average breathing loops for infant respiratory function testing.

Breathing loops can be obtained by plotting two respiratory signals on an x-y diagram: the resulting loops represent a non-parametric description of the respiratory system. In infancy, loops are commonly measured during tidal breathing and their interpretation is hampered by high within-subject variability. Therefore a two-dimensional averaging technique for loops has been developed. The algorithm is based on segmentation of the loops and required two steps. First, the total length of the loop of every breathing cycle was divided into a specified number of equidistant intervals and the co-ordinates calculated by stepwise linear approximation of the curve. Second, averaged loops were calculated using the arithmetical mean (or the median if there were artifacts) of the x and y co-ordinates of the loops for all calculated points. To compare the new technique with averaging in the time domain a simulation study was performed using respiratory signals with a coefficient of variation (CV) of 5%, 10%, 15% and 20%. In contrast to the new technique, with increasing CV, averaging in the time domain led to increasing contortions in the averaged flow-volume loops. Mean errors of peak tidal expiratory flow were -3.3%, -13.9%, -21.3% and -34.2%, whereas errors with the new technique were considerably lower (0.5%, 0.4%, 0.5% and -0.1%) and independent of the level of CV.

Algorithms↗
PubMed2001

[A model for primary and secondary metastasis in breast cancer and the clinical consequences].

BACKGROUND: An adjuvant locoregional radiotherapy after radical surgery results in a survival advantage for breast cancer patients. The advantage starts with a delay and reaches about 10% 15 years after diagnosis. What could explain such a delayed efficacy? METHODS: A population-based cohort from 1996 to 1998 and the Munich Cancer Registry with courses of breast cancer disease since 1977 are the empirical basis. The analysis concerns survival rates and survival times in respect to metastases, local and lymph node recurrencies. A metastatic model is derived from the data. RESULTS: A cohort of 9,347 patients with a mean follow-up of 6.5 years and 2,587 courses with metastases and/or local recurrencies were registered. The overall survival after 15 years was for pT1 57.6%, pT2 37.9%, pT3 24.4% and for pT4 10.5%. Five years after metastasization 20.1 to 12.4% survived, 10 years 6% independent on pT. Ten years after local recurrencies the survival was dependent on pT of the primary tumor: pT1 36.3%, pT2 21.0%, pT3 13.1% und pT4 4.6%. A local recurrency is a prognostic factor for metastasization of the primary tumor, but local recurrencies can also cause metastases. The mean survival time after metastasization of the primary pT1 tumor is estimated about 61 months, after metastasization by local recurrencies about 99 months with a mean time to local recurrencies of 38 months. Further results of the metastatic model are: the development of metastasization is homogeneous and independent on pT-category, the metastatic initiation starts up to 5 years before diagnosis, metastatic-free survival time and progression survival time are independent and an impact of lymph node recurrencies on survival could not be detected. CONCLUSIONS: The reduction of local recurrencies by high-quality primary therapy with radiotherapy and also the early detection of local recurrencies may reduce secondary metastasization and therefore improve survival. The metastasization model also explains the limitation of the therapeutical strategies and the almost mandatory chance of early detection programs of breast cancer.

Aged↗
PubMed2001

[Selection of subjects: a problem of clinical trials in traumatology. Selection effects and the problem of representation as exemplified by a prospective randomized trial on whiplash injuries].

INTRODUCTION: The internal and external validity of studies is endangered by many factors, such as selection of subjects for inclusion. Selection bias itself is a major problem, but remains unmentioned and probably unexamined in the majority of published clinical trials in traumatology. AIM OF THE STUDY: The aim of this investigation was to detect effects of subject selection which occurred during our own prospective intervention study. The clinical trial compared subjects with whiplash injury who were either treated by early mobilization or immobilization (soft collar). MATERIAL AND METHODS: Source population, eligible subjects, study participants and final study participants were compared for differences on various items like age, gender and further sociodemographic as well as crash related factors and clinical findings. RESULTS: Between 21.08.1997 and 30.04.1999 a total of 732 patients was examined and treated after whiplash in our trauma department. The options for inclusion were met by 453 patients. While 346 escaped from the study, 107 agreed to participate. Of these another 39 patients dropped out of the study. Selection effects were detected on two different levels, leading to distinct statistical procedures from those proposed in the study protocol. CONCLUSIONS: Uncontrolled selection effects could undermine the interpretability of the results of clinical trials. Awareness of selection effects is mandatory regarding the applicability of these results to subjects, other than those in the group of the final study participants.

Humans↗
PubMed2001

Characterization of pretectal-nuclear-complex afferents to the pulvinar in the cat.

We investigated anatomical and physiological properties of the projection from the pretectal nuclear complex (PNC) to the ipsilateral lateral posterior-pulvinar complex in the cat. After Phaseolus vulgaris leucoagglutinin injections into the PNC, the majority (70%) of anterogradely labeled terminals was localized in the pulvinar proper, the remaining 30% were scattered in the lateral and medial portions of the LP. No PNC neuron retrogradely labeled from the pulvinar was found to also express glutamic acid decarboxylase (GAD) mRNA, although a large number of neurons carrying the GAD label were found in close vicinity. In contrast, 69% of retrogradely labeled PNC cells also displayed glutamate-like immunoreactivity. Twenty-six out of 96 (27%) visually responsive pulvinar neurons were orthodromically activated by electrical stimulation of the ipsilateral PNC at latencies between 1 and 10 ms (median 1.9 ms). All orthodromically activated neurons responded well to the onset and offset of large visual stimuli and to sudden stimulus shifts. Whenever a saccadic eye movement was executed, these neurons were also activated, except during saccades in darkness. The comparison of saccade-evoked response with responses to visual stimuli that elicit similar retinal image shifts revealed that pretectorecipient pulvinar neurons also seem to receive a saccade-related non-visual input. All response properties correspond to those of a specific class of pulvinar neurons that have been termed "SV" neurons because they respond to visual stimulation as well as during saccades. They also closely resemble response properties of PNC neurons that project to the ipsilateral pulvinar. The results support the proposal that PNC cells not only directly activate their postsynaptic target neurons in the pulvinar, but that they also provide a visual input to these neurons that greatly contributes to their response characteristics.

Action Potentials↗
PubMed2001

X-ray photoelectron spectroscopy studies on adsorption of amino acids from aqueous solutions onto oxidised titanium surfaces.

Osseointegration is concerned with processes at the cellular level. However, the titanium surface is also capable of interactions with organic structures at the molecular level. These properties of titanium are presented from a physicochemical viewpoint. Adsorption experiments are described that should simulate molecular processes in the organism. The selected model substances, amino acids, were adsorbed from aqueous saline solutions with various pH values onto evaporated titanium layers. The evidence of adsorbates was determined by photoelectron spectroscopy. The pH values at which adsorption occurred, the binding energies and signal intensities according to curve fit allow conclusions to be drawn from the adsorption reactions. Thus, the titanium surface preferentially forms a surface complex with the carboxyl groups of the amino acids in an acidic solution. The resulting positions of the adsorbed molecules can be confirmed through evaluation of the line intensities. The results show clearly that there is chemical bonding between the titanium surface and the organic substances. Assuming that a comparable situation occurs in the organism, such processes or similar ones can be viewed as preliminary stages of osseointegration.

Adsorption↗
PubMed2001

Up-regulation of matrix metalloprotease-9 in middle ear cholesteatoma--correlations with growth factor expression in vivo?

The role of matrix metalloproteases and their regulation in the pathology of middle ear cholesteatoma is still unclear. Recently we have demonstrated that incubation of keratinocytes with cholesteatoma debris and granulation tissue extracts causes induction of gelatinase B (matrix metalloproteinase-9, MMP-9) secretion in vitro. Antibodies against a variety of growth factors revealed some inhibitory effect on MMP-9 induction, caused by debris or granulation tissue extracts. In order to investigate the coherence of growth factor expression and matrix metalloproteinase activity in vivo in middle ear cholesteatoma, we performed quantitative gelatin zymographic analysis with tissue homogenates of 37 cholesteatoma and nine external ear canal skin (EACS) samples. Furthermore we quantified levels of the cytokines IL-1alpha, IL-1beta, TNF-alpha, TGF-beta and EGF present in tissue extracts, using enzyme-linked immunosorbent assays (ELISA), and correlated cytokine concentrations with gelatinolytic activities. Zymographic analysis revealed a highly heterogeneous expression of gelatinase A and B in cholesteatoma specimens. As shown previously, MMP-9, but not MMP-2, was increased in cholesteatoma when compared to EACS samples. ELISA studies revealed a significantly elevated IL-1alpha level in cholesteatoma. Regression analysis involving gelatinolytic activity and cytokine concentrations in tissue homogenates showed no statistically significant correlation between expression of gelatinases and the cytokines IL1-alpha, IL1-beta, TNF-alpha, TGF-beta or EGF. The discrepancy between in vitro observations and the situation in vivo is discussed critically.

Cholesteatoma, Middle Ear↗
PubMed2001

Immunohistochemical localization of estrogen receptor-alpha in sex ducts and gonads of newborn piglets.

Estrogen receptor-alpha (ER-alpha) expression in piglet uteri has previously been reported from day 15 after birth. Nevertheless, uterine tissue has been reported to be estrogen sensitive from the day of birth. Since estrogen action in the uterine tissue is suggested to be mediated principally by ER-alpha, the present study aimed to evaluate the presence of ER-alpha in uteri of 1- to 2-day-old piglets by means of immunohistochemistry. In addition, sex ducts and gonads of both sexes were examined. The results clearly demonstrate the presence of ER-alpha immunopositive cells in uterine tissue, which explains its estrogen responsiveness. Immunostaining was most intense in the glandular epithelial cells and is suggested to indicate participation of ER-alpha in adenogenesis. In oviducts, almost all epithelial cells were immunostained moderately positive, while the stroma cells were stained comparably more positive. The functional significance of this intensity difference is uncertain but could indicate that part of the estrogen action on the epithelium is mediated through the stroma cells, as is known for the uterus. In ovaries, the surface epithelium and stroma cells were immunostained, whereas germ and granulosa cells were immunonegative. It is speculated that ER-alpha might be involved in yet unknown intraovarian mechanisms. In male sex ducts, immunostaining was virtually confined to the epithelium of efferent ducts. All cells in the epididymis as well as in vas deferens were immunonegative. The unique presence of ER-alpha in efferent ducts corresponds with localization in other species, where it has been shown to be involved in fluid reabsorption. The obtained data on localization of ER-alpha correspond with the present knowledge, obtained in ER-alpha knockout mice, of the biological function of ER-alpha within male and female gonads and sex ducts.

Animals↗
PubMed2001

Sequential chemo- and radiochemotherapy with weekly paclitaxel (Taxol) and 3D-conformal radiotherapy of stage III inoperable non-small cell lung cancer. Results of a dose escalation study.

The purpose of this study was the determination of the maximum tolerable dose (MTD) of weekly paclitaxel (PX) in combination with 3D-conformal radiotherapy in non-small cell lung cancer (NSCLC) and the evaluation of side effects, patient outcome and tumor response. Thirty-eight patients with inoperable NSCLC, UICC-stage IIIA (n=14)/IIIB (n=24) received two cycles of induction chemotherapy with PX/carboplatin followed by combined radiochemotherapy (60 Gy/6 weeks) with weekly PX which was escalated in cohorts of four patients until dose limiting toxicity (DLT) was reached. Starting level was 40 mg/m(2). 3D-conformal radiotherapy was applied in all patients. Toxicity was determined by WHO criteria. Patients were followed-up 3-monthly. Thirty eight patients have entered the study, 34 patients are evaluable. DLT was esophagitis III degrees, requiring interruption of radiotherapy and was reached at the PX 70 mg/m(2). Two hypersensitivity reactions (50 mg/m(2)) and one leucopenia III degrees (60 mg/m(2)) were observed. Only one patient (60 mg/m(2), 50 Gy) completely aborted treatment. The pneumonitis rate was between 21 and 36% but showed no clear correlation with PX dose. Tumor response (PR and CR) defined by CT-scan 6 weeks following radiotherapy was 88% (30/34). The 1- and 2-year survival rate is 73% and 34%. We conclude that the MTD of weekly PX with 60 Gy normofractionated radiotherapy is 60 mg/m(2). The DLT is esophagitis. Response and survival data of this sequential/combined approach are promising. A minor increase of pulmonary toxicity of irradiation is suspected.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Intratype HPV16 sequence variation within LCR of isolates from asymptomatic carriers and cervical cancers.

BACKGROUND: HPV16 is a predominant type of virus identified in genital lesions and strongly associated with the development of genital cancers. Infection with the virus is considered to be the main risk factor in the development of cervical cancer. Based on HPV16 DNA isolated from invasive cancers, a classification of intratype genetic variants was established and the strains were designated according to geographical regions. The HPV16 variants classification was based on isolates derived from cancers. OBJECTIVES: Analysis of HPV16 LCR variants isolated from asymptomatic carriers for comparison with cervical cancer isolates to examine whether a correlation can be found between cervical epithelium state and variant of HPV16 it carries. MATERIALS AND METHODS: The HPV16 LCR fragments were amplified by PCR using DNA isolated from cervical swabs and tissue sections then screened for nucleotide changes by SSCP. Polymorphic sites were analysed for regulatory protein binding properties by EMSA. RESULTS: Comparison of the two groups revealed that isolates from cervical cancers predominantly carry changes in sequences of YY1 binding sites (especially at nucleotide 7519), while variants from asymptomatic carriers contained nucleotide changes within or close to transcription binding sites for AP-1, Oct-1, NF1, Tef-1, Tef-2, Sp1, YY1 and viral E2. EMSA study showed that sequence changes in the segment alter binding and formation of transcriptional complexes in quantitative and/or qualitative manner and so they may inflict viral activity. CONCLUSION: The results of our study show that there might be HPV16 variants of decreased oncogenic potential therefore infection with such variants can recede.

Binding Sites↗
PubMed2001

Interactions between esterified whey proteins (alpha-lactalbumin and beta-lactoglobulin) and DNA studied by differential spectroscopy.

Spectroscopic study of interactions between esterified whey proteins and nucleic acids, at neutral pH, showed positive differential spectra over a range of wavelength between 210 and 340 nm. In contrast, native forms of whey proteins added to DNA did not produce any differential spectra. The positive difference in UV absorption was observed after addition of amounts of proteins as low as 138 molar ratio (MR) of protein/DNA, indicating high sensitivity of the applied method to detect interactions between basic proteins and DNA. UV-absorption differences increased with MR of added whey protein up to saturation. The saturation points were reached at relatively lower MR in the case of methylated forms of the esterified protein as compared to its ethylated form. Saturation of nucleic acid (2996 bp long) was achieved using 850 and 1100 MR of methylated beta-lactoglobulin and of methylated alpha-lactalbumin, respectively. Saturation with ethylated forms of the proteins was reached at MR of 3160 and 2750. Lysozyme, a native basic protein, showed a behavior similar to what was observed in the case of methylated forms of the dairy proteins studied. However, in the case of lysozyme, saturation was achieved at relatively lower MR (700). Methylated ,-casein failed to give positive spectra at pH 7 in the presence of DNA. It interacted with DNA only when the pH of the medium was lowered to 6.5, below its pI. Generally, amounts of proteins needed to saturate nucleic acid were much higher than those needed to neutralize it only electrostatically, demonstrating the presence on DNA of protein-binding sites other than the negative charges on the sugar-phosphate DNA backbones. Addition of 0.1% SDS to the medium suppressed totally all spectral differences between 210-340 nm. The presence of 5 M urea in the medium reduced only the spectral differences between 210-340 nm, pointing to the role played by hydrophobic interactions. Peptic hydrolysates of esterified and native proteins or their cationic fractions (pH > 7) produced negative differential spectra when mixed with DNA. The negative differences in UV absorption spectra were the most important in the case of peptic hydrolysates of methylated derivatives of whey proteins.

DNA↗
PubMed2001

Synthesis and biological evaluation of destruxin A and related analogs.

This report describes the development of an efficient solid-phase synthesis protocol and adaptation of reported solution phase procedures for the synthesis of the cyclic depsihexapeptide destruxin A and related analogs. The solid-phase method described is based on standard Fmoc peptide chemistry, including a new synthetic method for the assembly of the depsi bond-containing unit. In order to select analogs of destruxin A for synthesis and evaluation of insecticidal activity, the work of Hellberg et al., describing a set of Z-descriptors for amino acid side-chains comparing their physicochemical properties, was utilized. Destruxin A and 27 different analogs with structural variations in four residues were synthesized and insecticidal activity was evaluated via injections into tobacco budworm (Heliothis virescens) larvae. Several destruxin A analogs were found to be at least as potent as the native compound.

Animals↗
PubMed2001

Prognostic relevance of hMLH1, hMSH2, and BAX protein expression in endometrial carcinoma.

Endometrial carcinoma is the most common gynecologic malignancy in perimenopausal and postmenopausal women. A role of mismatch repair genes, like hMLH1 and hMSH2 in their pathogenesis, has been suggested. Loss of their function leads to the accumulation of replication errors (mutator phenotype), which are responsible for further mutations in genes with microsatellite sequences in their coding region, such as Bax. We analyzed the expression of hMLH1, hMSH2, and Bax genes in 89 formalin-fixed paraffin-embedded endometrial carcinomas. The immunostains were scored with regard to percentage of positive tumor cells (0%, <10%, 10 to 50%, >50%), and relative staining intensity (1+, 2+, 3+). The staining results were correlated with clinicopathologic features and survival. Loss of hMSH2 expression (0% positive cells) was observed in 1.1% (1/89) of the tumors; loss of hMLH1 was seen in 12.4% (11/89) of the cases, particularly in endometrioid tumors with mucinous differentation (5/11; 45%; P =.03). No significant association was found between the immunoscores and grade, stage criteria of the International Federation of Obstetrics and Gynecology (FIGO), or age of the patients. Among 11 tumors with loss of Bax expression (12.4%), 4 had also loss of hMLH1 (4/11; 36.4%; P =.017). In multivariate analysis (Cox model), significantly longer survival was found for patients with tumors in FIGO Stage I-II (P <.0001), endometrioid type (P =.001), low grade (P =.001), and absence of hMLH1 expression (P =.027). Our results suggest that loss of function of hMLH1 and Bax occur in a subgroup of endometrial carcinoma. In addition to the classical prognostic factors, absence of hMLH1 expression is associated with better outcome of patients.

Adaptor Proteins, Signal Transducing↗
PubMed2001

A new phospholipase-C-calcium signalling pathway mediated by cyclic AMP and a Rap GTPase.

Stimulation of phosphoinositide-hydrolysing phospholipase C (PLC) generating inositol-1,4,5-trisphosphate is a major calcium signalling pathway used by a wide variety of membrane receptors, activating distinct PLC-beta or PLC-gamma isoforms. Here we report a new PLC and calcium signalling pathway that is triggered by cyclic AMP (cAMP) and mediated by a small GTPase of the Rap family. Activation of the adenylyl cyclase-coupled beta2-adrenoceptor expressed in HEK-293 cells or the endogenous receptor for prostaglandin E1 in N1E-115 neuroblastoma cells induced calcium mobilization and PLC stimulation, seemingly caused by cAMP formation, but was independent of protein kinase A (PKA). We provide evidence that these receptor responses are mediated by a Rap GTPase, specifically Rap2B, activated by a guanine-nucleotide-exchange factor (Epac) regulated by cAMP, and involve the recently identified PLC-epsilon isoform.

Adenylyl Cyclases↗
PubMed2001

Postnatal maturation of GABA(A) and GABA(C) receptor function in the mammalian superior colliculus.

In the stratum griseum superficiale (SGS) of the mammalian superior colliculus, GABA(C) receptors seem to control the excitability of projection neurons by selective inactivation of local GABAergic interneurons. As the onset of visual responses to SC begins well after birth in the rat, it is possible to study developmental changes in GABAergic mechanisms that are linked to the onset of visual information processing. In order to analyse postnatal changes in inhibitory mechanisms that involve GABA receptor function, we used extracellular field potential (FP) recordings and single cell patch-clamp techniques in slices from postnatal day 4 (P4) to P32 and examined the effects of GABA and muscimol on electrically evoked SGS cell activity. While GABA(A) receptor activation affected FP amplitudes throughout postnatal development, GABA(C) receptor activation did not significantly change FP amplitudes until the third postnatal week. Results from patch-clamping single cells, however, clearly demonstrate that GABA(C) receptors are already functional at P4--similar to GABA(A) receptors. Throughout postnatal development, activation of GABA(C) receptors leads to a strong inhibition of inhibitory postsynaptic activity, indicating that GABA(C) receptors are expressed by inhibitory interneurons. Furthermore, the proportion of neurons that show decreased excitatory postsynaptic activity during GABA(C) receptor activation correlates with the proportion of GABAergic interneurons in SGS. Our patch-clamp results indicate that the functional expression of GABA(C) receptors by GABAergic interneurons does not change significantly during postnatal development. However, our measurements of FP amplitudes indicate that the maturation of the efferent connections of these GABAergic neurons within SGS during the third postnatal week strongly changes GABA(C) receptor function.

Aging↗
PubMed2001

Xenon expenditure and nitrogen accumulation in closed-circuit anaesthesia.

The high price of xenon has prevented its use in routine, clinic anaesthetic practice. Xenon therefore has to be delivered by closed-circuit anaesthesia. The accumulation of nitrogen is a significant problem within the closed circuit and necessitates flushing, which in turn increases gas expenditure and costs. In previous investigations, nitrogen concentrations between 12% and 16% have been reported in closed-circuit anaesthesia. In order to avoid such nitrogen accumulation, we denitrogenised seven pigs using a non-rebreathing system and connected the animals to a system primed with a xenon/oxygen mixture. In comparison, seven pigs were anaesthetised with xenon using a standard low-flow anaesthetic procedure. Anaesthesia time was 2 h. Nitrogen concentrations in the closed system ranged from 0.08 to 7.04% and were not significantly different from those observed during low-flow anaesthesia. Closed-circuit anaesthesia reduced the xenon expenditure 10-fold compared with low-flow anaesthesia.

Anesthesia, Closed-Circuit↗