Biomedical subjects

M A Schwarz

Publications and source records attributed to M A Schwarz.

At least 19 recordsLinked to original sources

PubMed2002

Pro-EMAP II is not primarily cleaved by caspase-3 and -7.

Endothelial monocyte-activating polypeptide (EMAP) II is a unique cytokine, also known as p43, the active mature form of which exhibits antiangiogenic properties in vivo and in vitro. The proteolytic enzymes associated with the cleavage and release of the active mature form, however, remain unclear. Here we show that, in contrast to prior observations, purified pro-EMAP II is not cleaved by either caspase-3 or -7 in vivo or in vitro. Thus other proteolytic processes, which allow it to induce apoptosis via caspase-3 activation in migrating and dividing endothelium, may be involved in the release of the active mature EMAP II.

Animals↗

PubMed2001

Rapid chiral on-chip separation with simplified amperometric detection.

The enantiomers of adrenaline, noradrenaline, ephedrine and pseudoephedrine were separated by capillary electrophoresis on a micromachined device. Detection was carried out with a new two-electrode amperometric detector, eliminating the need for individual counter and reference electrodes. Separation of the isomers was achieved by employing carboxymethyl-beta-cyclodextrin as chiral selector in the buffer, partly with the additional inclusion of the crown ether 18-crown-6. Plate numbers of up to 20,000, chiral resolutions of 2.5 and detection limits of the order of 10(-7) M were achieved. All separations were completed in less then 3 min.

Electrochemistry↗

PubMed2001

Recent developments in detection methods for microfabricated analytical devices.

Sensitive detection in microfluidic analytical devices is a challenge because of the extremely small detection volumes available. Considerable efforts have been made lately to further address this aspect and to investigate techniques other than fluorescence. Among the newly introduced techniques are the optical methods of chemiluminescence, refraction and thermooptics, as well as the electrochemical methods of amperometry, conductimetry and potentiometry. Developments are also in progress to create miniaturized plasma-emission spectrometers and sensitive detectors for gas-chromatographic separations.

Journal Article↗

PubMed2001

The management of testicular cancer in Victoria, 1988-1993. Urology Study Committee of the Victorian Co-operative Oncology Group.

OBJECTIVES: To evaluate the patterns of care and management of testicular cancer in Victoria. DESIGN AND SETTING: Retrospective analysis of all cases of testicular cancer in Victoria from 1988 to 1993 identified through the Victorian Cancer Registry. MAIN OUTCOME MEASURES: Description of patient characteristics, staging investigations, initial management, and outcome. RESULTS: 667 eligible cases of testicular cancer were identified and questionnaires were returned for 633 of these patients (94.9% response rate). There were 357 (56.4%) patients with pure seminoma; 271 (42.8%) with non-seminomatous germ cell tumours, 3 (0.5%) with stromal tumours, and 2 (0.3%) with other tumours. The median age was 32 years (range, 0-80 years). Preoperative marker levels were not available for 8% of patients, and initial staging was considered inadequate in 6%. Surveillance programs used for patients with Stage I disease were considered inadequate in most. Relative survival at five years was 99% for patients with seminoma and 91% for non-seminoma. CONCLUSIONS: There was considerable variation in the investigation, treatment, and follow-up of these patients, which is likely to have resulted in unnecessary morbidity. Clinical practice guidelines should be developed and implemented to promote optimal management.

Adolescent↗

PubMed2001

Control of stromal keratitis by inhibition of neovascularization.

Stromal keratitis resulting from ocular infection with herpes simplex virus is a common cause of blindness. This report investigates the role of neovascularization in the pathogenesis of stromal keratitis by measuring the outcome of treatment with the potent anti-angiogenesis cytokine endothelial monocyte-activating polypeptide II (EMAP II). We show that systemic and topical administration of EMAP II from the outset of infection resulted in markedly diminished levels of herpes simplex virus-induced angiogenesis and significantly reduced the severity of stromal keratitis lesions. EMAP II treatment had no demonstrable pro-inflammatory or toxic effects and failed to express antiviral activity. The mechanism of action of EMAP II was shown to proceed by causing apoptosis in vascular endothelial cells. Our data document for the first time the essential role of angiogenesis in the pathogenesis of stromal keratitis and also indicate that the therapy of herpetic stromal keratitis could benefit by procedures that diminish angiogenesis.

Angiogenesis Inhibitors↗

PubMed2001

A two-electrode configuration for simplified amperometric detection in a microfabricated electrophoretic separation device.

The simplified amperometric detection scheme demonstrated is based on the amperometric working and electrophoretic ground electrodes only. The latter serves as counter and pseudo-reference as well. It is shown via the successful determination of neurotransmitters, ascorbic acid and phenols on gold or platinum working electrodes that this approach is feasible for detection on a channel based electrophoretic separation device. Also presented is the detection of carbohydrates and amino acids with copper electrodes. The results were found to be similar to those obtained with conventional capillary systems with amperometric detection, albeit at much reduced analysis times.

Journal Article↗

PubMed2001

Acute lung injury: cellular mechanisms and derangements.

The clinical course of acute lung injury (ALI) is a complex and variable process accompanied by severe lung dysfunction, which persists for a long period of time with variable recovery of pulmonary function. The extent and severity of the lung disease associated with ALI varies with those patients having the most severe manifestations of lung disease being grouped as acute respiratory distress syndrome (ARDS). The pathological injury associated with this disease process, termed diffuse alveolar damage (DAD), has three overlapping phases (exudative, proliferative and fibrotic) which are the consequences of severe injury to the alveolar-capillary unit. There is no uniformity to the progression and length of each stage. This review explores those cellular mechanisms and derangements involved in the progression of ARDS. Those areas that demonstrate the major advances within the field are highlighted because of the diverse and vast nature of the cellular components involved in the process of ALI. We are beginning to identify those processes that contribute to the cellular derangements which are the hallmark of ALI. By expanding our understanding of those factors, we should in the future be able to construct therapeutic interventions that address the aetiology of ALI.

Child↗

PubMed2000

Antiangiogenic treatment enhances photodynamic therapy responsiveness in a mouse mammary carcinoma.

Photodynamic therapy (PDT) is a promising cancer treatment that induces localized tumor destruction via the photochemical generation of cytotoxic singlet oxygen. PDT-mediated oxidative stress elicits direct tumor cell damage as well as microvascular injury within exposed tumors. Reduction in vascular perfusion associated with PDT-mediated microvascular injury produces tumor tissue hypoxia. Using a transplantable BA mouse mammary carcinoma, we show that Photofrin-mediated PDT induced expression of the hypoxia-inducible factor-1alpha (HIF-1alpha) subunit of the heterodimeric HIF-1 transcription factor and also increased protein levels of the HIF-1 target gene, vascular endothelial growth factor (VEGF), within treated tumors. HIF-1alpha and VEGF expression were also observed following tumor clamping, which was used as a positive control for inducing tissue hypoxia. PDT treatment of BA tumor cells grown in culture resulted in a small increase in VEGF expression above basal levels, indicating that PDT-mediated hypoxia and oxidative stress could both be involved in the overexpression of VEGF. Tumor-bearing mice treated with combined antiangiogenic therapy (IM862 or EMAP-II) and PDT had improved tumoricidal responses compared with individual treatments. We also demonstrated that PDT-induced VEGF expression in tumors decreased when either IM862 or EMAP-II was included in the PDT treatment protocol. Our results indicate that combination procedures using antiangiogenic treatments can improve the therapeutic effectiveness of PDT.

Angiogenesis Inhibitors↗

PubMed2000

Temporo-spatial distribution of endothelial-monocyte activating polypeptide II, an anti-angiogenic protein, in the mouse embryo.

We describe the temporo-spatial distribution of Endothelial-Monocyte Activating Polypeptide (EMAP) II in order to better understand what role this anti-angiogenic proteins may play in fetal development. In situ hybridization, immunohistochemistry, and Western analysis were performed on fetal, neonatal, and adult tissue. EMAP II was first detected only within the central nervous system on 9 days postcoitum (dpc). Subsequently, at 11 through 18 dpc, EMAP II expression was detected in the respiratory, central nervous, cardiovascular, urogenital systems, sense organs, and digestive tract. EMAP II mRNA and protein was localized to the epithelium, with its highest expression in neurons, blood vessels, and at sites of epithelial-mesenchymal interaction. The temporo-spatial distribution of EMAP II suggests that it could play an important role in morphogenesis of the vertebrate embryo.

Angiogenesis Inhibitors↗

PubMed2000

Endothelial monocyte activating polypeptide II inhibits lung neovascularization and airway epithelial morphogenesis.

Neovascularization is crucial to lung development and is mediated through a variety of angiogenic and anti-angiogenic factors. Herein, we show that excess Endothelial Monocyte Activating Polypeptide (EMAP) II, an anti-angiogenic protein, not only inhibits fetal lung neovascularization, but also significantly alters airway epithelial morphogenesis. In a murine allograft model of lung neovascularization and morphogenesis, embryonic lungs transplanted under the skin of immunocompromised mice receiving intraperitoneal EMAP II, had a 56% reduction in vessel density (P<0.0001) compared to control. EMAP II treated lung transplants also exhibited a marked alteration in lung morphogenesis, including lack of type II alveolar cell formation, determined by markedly decreased expression of surfactant protein C, and increased apoptosis. In contrast, lung implants in animals receiving an EMAP II blocking antibody had an increase in vessel density of 50% (P<0.0001) and increased expression of surfactant protein C mRNA in distal epithelium. These studies demonstrate that EMAP II negatively modulates lung neovascularization as well as leading to the arrest of lung airway epithelial morphogenesis and apoptosis.

Angiogenesis Inhibitors↗

PubMed2000

Angiogenesis and morphogenesis of murine fetal distal lung in an allograft model.

Neovascularization is crucial to lung morphogenesis; however, factors determining vessel growth and formation are poorly understood. The goal of our study was to develop an allograft model that would include maturation of the distal lung, thereby ultimately allowing us to study alveolar development, including microvascular formation. We transplanted 14-day gestational age embryonic mouse lung primordia subcutaneously into the back of nude mice for 3.5-14 days. Lung morphogenesis and neovascularization were evaluated by light microscopy, in situ hybridization, and immunohistochemical techniques. Embryonic 14-day gestational age control lungs had immature structural features consistent with pseudoglandular stage of lung development. In contrast, 14 days after subcutaneous transplantation of a 14-day gestational age lung, the allograft underwent significant structural morphogenesis and neovascularization. This was demonstrated by continued neovascularization and cellular differentiation, resulting in mature alveoli similar to those noted in the 2-day postnatal neonatal lung. Confirmation of maturation of the allograft was provided by progressive type II epithelial cell differentiation as evidenced by enhanced local expression of mRNA for surfactant protein C and a threefold (P < 0.008) increase in vessel formation as determined by immunocytochemical detection of platelet endothelial cell adhesion molecule-1 expression. Using the tyrosine kinase Flk-1 receptor (flk-1) LacZ transgene embryos, we determined that the neovascularization within the allograft was from the committed embryonic lung endothelium. Therefore, we have developed a defined murine allograft model that can be used to study distal lung development, including neovascularization. The model may be useful when used in conjunction with an altered genetic background (knockout or knock in) of the allograft and has the further decided advantage of bypassing placental barriers for introduction of pharmacological agents or DNA directly into the lung itself.

Animals↗

PubMed1999

Endothelial-monocyte activating polypeptide II, a novel antitumor cytokine that suppresses primary and metastatic tumor growth and induces apoptosis in growing endothelial cells.

Neovascularization is essential for growth and spread of primary and metastatic tumors. We have identified a novel cytokine, endothelial-monocyte activating polypeptide (EMAP) II, that potently inhibits tumor growth, and appears to have antiangiogenic activity. Mice implanted with Matrigel showed an intense local angiogenic response, which EMAP II blocked by 76% (P < 0.001). Neovascularization of the mouse cornea was similarly prevented by EMAP II (P < 0.003). Intraperitoneally administered EMAP II suppressed the growth of primary Lewis lung carcinomas, with a reduction in tumor volume of 65% versus controls (P < 0.003). Tumors from human breast carcinoma-derived MDA-MB 468 cells were suppressed by >80% in EMAP II-treated animals (P < 0.005). In a lung metastasis model, EMAP II blocked outgrowth of Lewis lung carcinoma macrometastases; total surface metastases were diminished by 65%, and of the 35% metastases present, approximately 80% were inhibited with maximum diameter <2 mm (P < 0.002 vs. controls). In growing capillary endothelial cultures, EMAP II induced apoptosis in a time- and dose-dependent manner, whereas other cell types were unaffected. These data suggest that EMAP II is a tumor-suppressive mediator with antiangiogenic properties allowing it to target growing endothelium and limit establishment of neovasculature.

Animals↗

PubMed1999

Metastasis correlates with production of vascular endothelial growth factor in a murine model of human Wilms' tumor.

BACKGROUND/PURPOSE: The growth and spread of solid tumors are critically dependent on the induction of angiogenesis. We hypothesized that vascular endothelial growth factor (VEGF) would be detected in Wilms' tumors, and that both growth and metastasis would parallel VEGF levels in a murine model. METHODS: Primary tumors were established in the right kidneys of nude mice (n = 21). Mice were killed at 3, 4.5, or 6 weeks. Tumor-bearing and control kidneys were subjected to enzyme-linked immunosorbent assay (ELISA) for VEGF. Representative sections were assessed by histology and immunohistochemistry. Lungs were examined for metastases. Clinical specimens of Wilms' tumor (n = 12) also were assayed for VEGF. RESULTS: The authors detected VEGF by ELISA with increasing frequency, and in increasing quantity, as experimental Wilms' tumors were grown over time. Immunohistochemistry demonstrated accumulation of VEGF in areas of viable tumor. Lung metastases occurred in 8 of 10 animals with VEGF-positive tumors, but in only 3 of 11 animals with VEGF-negative tumors, an association that was statistically significant. VEGF was found in 10 of 12 clinical Wilms' tumor specimens tested. CONCLUSIONS: VEGF is present in both clinical and experimental Wilms' tumors. In a murine model, absolute VEGF levels increase as primary tumors grow, and VEGF production is significantly associated with tumor metastasis.

Animals↗

PubMed1999

Wheatgerm agglutinin-mediated toxicity in pancreatic cancer cells.

Lectin binding specificities for carbohydrate allow phenotypic and functional characterization of membrane-associated glycoproteins expressed on cancer cells. This analysis examined wheatgerm agglutinin binding to pancreatic cancer cells in vitro and the resulting toxicity. Membrane preparations of nine human pancreatic carcinoma cell lines were studied for lectin binding using wheatgerm agglutinin (WGA), concanavalin A (ConA) and phytohaemagglutinin-L (PHA-L) in a lectin blot analysis. Cell proliferation in vitro was measured by thymidine incorporation in the absence or presence of lectins at various concentrations. Sialic acid binding lectins or succinyl-WGA (succWGA) served as controls. WGA toxicity was tested after swainsonine or neuraminidase pretreatment. Binding and uptake of fluorescein-labelled lectins was studied under fluorescence microscopy. All pancreatic cell lines displayed high WGA membrane binding, primarily to sialic acid residues. Other lectins were bound with weak to moderate intensity only. Lectin toxicity corresponded to membrane binding intensity, and was profound in case of WGA (ID50 at 2.5-5 microg ml(-1)). WGA exposure induced chromatin condensation, nuclear fragmentation and DNA release consistent with apoptosis. Important steps for WGA toxicity included binding to sialic acid on swainsonine-sensitive carbohydrate and lectin internalization. There was rapid cellular uptake and subsequent nuclear relocalization of WGA. In contradistinction to the other lectins studied, WGA proved highly toxic to human pancreatic carcinoma cells in vitro. WGA binding to sialic acid residues of N-linked carbohydrate, cellular uptake and subsequent affinity to N-acetyl glucosamine appear to be necessary steps. Further analysis of this mechanism of profound toxicity may provide insight relevant to the treatment of pancreatic cancer.

Antineoplastic Agents↗

PubMed1999

Affinity capillary electrophoresis in pharmaceutics.

The technique of Affinity capillary electrophoresis (ACE) is a useful tool to characterize complexation and partition equilibria. A wide range of applications in pharmaceutics has been presented: the determination of pKA values, of association constants between drugs and cyclodextrins or amphiphilic compounds as well as the characterization of drug affinities to several vehicle systems, such as micelles, microemulsions and liposomes. Due to the widespread use of capillary electrophoresis in drug analysis, the technical equipment is quite common. ACE is advantageous as a rapid and simple screening method which provides quantitative results about various interactions with a minimum of substance consumption and time spent.

Chemistry, Pharmaceutical↗

PubMed1998

Characterization of micelles by capillary electrophoresis.

A practical approach for the characterization of pure micelles, and binary or ternary mixed micelles by capillary electrophoretic methods is presented. Interest is focused on the determination of mobility and composition of the micelles. The investigations are performed with bile salts, phosphatidylcholines and fatty acids. Pure bile salt micelles are characterized with the help of marking and displacement methods. Binary bile salt/phospholipid and ternary bile salt/phospholipid/fatty acid micelles are analyzed using capillary electrophoresis (CE) techniques with standard and improved UV detection, laser-induced fluorescence and electrospray ionization-mass spectrometry (ESI-MS). For both the binary and the ternary systems, only one stable mixed micellar phase is found with a high negative mobility.

Bile Acids and Salts↗

PubMed1998

Interaction between food components and drugs. Part 6: Influence of starch degradation products on propranolol transport.

Interactions between different starch degradation products and propranolol (P) were studies using permeation experiments and affinity capillary electrophoresis (ACE). In the presence of maltooligosaccharides (MO), the transport of P across artificial lipid membranes was retarded. The most intensive interaction with the drug was found in the presence of the not-debranched MO from maize starch. The electrophoretic mobility mu of the drug was decreased in dependence of the MO concentration. However calculation of equilibrium binding constants from the ACE experiments was not possible because of the relatively weak influence of starch degradation products on the electrophoretic behaviour of the drug. With both methods the same tendency in strength of interactions between the different MO and P was found. Molecular parameters of the MO and their viscosity play a role in the interactions and in the decreased permeation of the drug.

Biological Transport↗

PubMed1996

Application of capillary electrophoresis of characterizing interactions between drugs and bile salts. Part I.

Capillary electrophoresis offers a new way of characterizing interactions between different bile salts and drugs. The observed interactions were characterized with modified model functions known from affinity capillary electrophoresis (ACE) an micellar electrokinetic capillary electrophoresis (MECC). The methodical background of both methods is the change of the ionic mobility of the drug caused by partition between phases and aggregation with the bile salt molecules, respectively. This phenomenon is described by two different physicochemical models. A parameter estimation was carried out in order to obtain the partition coefficients KP as well as constants for the aggregate formation KA. Furthermore, an expression about the specific molar volume of the micelles and stoichiometric coefficients can be given.

Atenolol↗