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Biomedical subjects

P Schwartz

Publications and source records attributed to P Schwartz.

At least 19 recordsLinked to original sources
PubMed2006

Structural, biochemical and functional aspects of sperm-oocyte interactions in pigs.

Polyspermic fertilization is still a major issue in porcine IVF systems. New information is available to characterize the zona pellucida (ZP) at different developmental stages by scanning electron microscopy (SEM) and by confocal microscopy to show the distribution of ZP glycoproteins. SEM images indicated no differences between in vivo and in vitro matured oocytes; however a change in the surface structure between immature and matured oocytes, as well as between mature oocytes and preimplantation embryos was obvious. In addition, spermatozoa were more tightly fixed in the ZP of in vivo produced compared to the ZP of in vitro produced embryos. The ZP undergoes biochemical changes during maturation prior to fertilization. The acidity of the ZP increases during maturation as indicated by a shift of 1.3 pl units for ZPB/ZPC and 0.8 pl units for ZPA in 2D gel electrophoresis, which is based on increasing sulfation of the oligosaccharides during maturation. Mass spectrometry in combination with in-gel deglycosylation allowed the mapping of new glycosylation sites. Functionality of the ZP also depends on its maturation status. Induction of the acrosome reaction was delayed when capacitated spermatozoa were exposed to immature oocytes.

Animals↗
PubMed2005

[In-vitro study of the cellular response of human fibroblasts cultured on alloplastic hernia meshes. Influence of mesh material and structure].

BACKGROUND: The biocompatibility of meshes in hernia surgery seems to be influenced markedly by the amount of the selected material and its structure. Fibroblasts play a major key role during the process of mesh incorporation. This study was performed to investigate differences in cell morphology and proliferation of human fibroblasts cultured on different polypropylene meshes. METHODS: In the present in vitro study the cellular response of human fibroblasts was investigated by scanning electron microscopy (SEM), comparing three different polypropylene meshes: a newly constructed low-weight and microporous mesh (NK1), a low-weight and macroporous mesh with absorbable polyglactin filaments (Vypro), and a heavy-weight and microporous mesh (BiomeshP1). Human fibroblasts (1,5.10(5) cells) were incubated with the meshes (each 12 mm(2)) for 6 hours, 5 days, 2, 4, 6, and 12 weeks. Computer-assisted morphometry of the fibroblast/mesh surface ratio served to reflect the biological cell response. RESULTS: The Vypro mesh showed the significantly highest fibroblast density during the first 6 weeks, but cell growth was nearly exclusively limited to the polyglactin filaments. At 3 months, after reabsorption of the polyglactin, the fibroblast-coated polypropylene mesh surface was only 50% compared to NK1 and BiomeshP1. The morphologic aspect of the fibroblasts on the BiomeshP1 mesh was much more degenerative and unphysiological, compared to NK1 and Vypro, with isolated, single cells instead of a broad, connective growth. The BiomeshP1 showed a significantly higher fibroblast proliferation around the nodes of the mesh compared to the straight filaments. On the NK1 mesh fibroblasts exclusively proliferated on the filaments but not on the pressed mesh surface. CONCLUSIONS: The polymer surface and structure appears to be of major importance for the biocompatibility of meshes: human fibroblasts preferably grow on low-weight meshes, thin filaments, and mesh nodes. Heavy-weight meshes induce degenerative cell reactions. Polyglactin seems to further improve cell proliferation whereas a pressed mesh surface without pores hinders fibroblast growth.

Cell Count↗
PubMed2005

[Influence of different mixing fluids on mechanical and micromorphological in vitro qualities of hydroxyapatite cement].

AIM: In reconstructive craniofacial surgery a new synthetic hydroxyapatite cement has been used in the last few years. Tetra- and dicalcium phosphates react with either slow setting aqua bidest. or with faster setting sodium monophosphate solution to hydroxyapatite. The aim of this study was to investigate the two mixing fluids of hydroxyapatite for resulting micromorphology, pressure strength, and interactions with fibroblasts. MATERIAL AND METHODS: Pressure strength tests of hydroxyapatite cement test samples (n=80) were performed after a setting time of 3 and 24 h. The micromorphology of surfaces of the resulting particles was assessed under an electron microscope. In cell cultures L-929 and HEp2 cells were incubated with test samples and cell growth was assessed by light and electron microscopy. RESULTS: The test samples mixed with sodium monophosphate solution showed statistically significantly higher values of pressure strength. The resulting pressure strength depended on respective mixing fluids, setting time, and pressure of application. In general, test samples mixed with sodium monophosphate solution showed a more load-stable, homogeneous anorganic matrix whereas test samples mixed with aqua bidest. had a porous microarchitecture which was more fragile. In cell culture the porous structure showed disintegration in cell culture medium. CONCLUSION: To what extent the two mixing liquids of hydroxyapatite cement influence the resorption and bony substitution has to be shown in further studies.

Animals↗
PubMed2004

Echogenicity of breast cancer: is it of prognostic value?

Echogenicity of colorectal metastases to the liver has been shown to correlate with prognosis. While there have been many studies looking at the echogenicity of breast cancer, there has been no study relating the issue of echogenicity to prognosis of breast cancer. In this study, we found that hyperechoic and mixed echogenicity breast cancers are rare compared to hypoechoic breast cancers. There was, however, no difference in the groups with respect to histological size, grade, axillary metastases, hormone receptor status and lymphovascular invasion.

Adenocarcinoma↗
PubMed2003

Oocyte-sperm interaction in the course of IVF: a scanning electron microscopy analysis.

Interaction between the spermatozoon and the zona pellucida during the first steps of fertilization was analysed on approximately 500 polyploid and unfertilized IVF oocytes by scanning electron microscopy (SEM). Oocytes demonstrate high inter- and intra-individual variations in size and morphology which do not correlate either with the maturity of the oocytes or with the age of the women. During gamete interaction, corona radiata cells are widely dispersed around the zona but are still in contact with it through cytoplasmic filaments. Channels between granulosa cells guide spermatozoa towards the zona. In the course of fertilization, different types of attachment of the spermatozoon to the oocyte occur. Most commonly, a flat, tangential attachment of the sperm head to the surface of the zona appears, which is then followed by intrusion into the zona in precisely this horizontal position. However, vertical binding with penetration by the tip of the head first also occurs. In oocytes where large, cluster-like numbers of bound spermatozoa are visible, vertical binding and penetration is the most usual position. In the process of gamete interaction, both spermatozoa and zona pellucida are actively involved. Spermatozoa, including their tails, which are attached to the zona, are overgrown by filaments of zona material. These filaments of the zona are made of granules, which are the basic components of zona material. After the removal of the zona pellucida by laser, the oolemma becomes visible. It is covered by microvilli of highly variable numbers. Between these microvilli, cortical granules are evident, and appear even before sperm penetration.

Female↗
PubMed2003

Ultrastructural changes of cardiac valves in bacterial endocarditis.

AIM: The principal objective of this study was to document morphological changes in valves with acute endocarditis in order to gain further knowledge of the pathogenesis of these diseases. METHODS: Scanning and transmission electron microscopic investigations were carried out on explanted human heart valves to reveal ultrastructural changes due to bacterial endocarditis. RESULTS: Bacterial inflammation endocarditis initially induced metaplasia of the endothelial cells which then lose contact with each other. In the 2nd phase of the disease, the collagen fibres are systematically removed whereby large cavities appear. In the 3rd phase, localised hyperplasia of collagen fibres was observed often resulting in the development of vegetation. The ultrastructural changes are uniform and independent of the bacterial species. CONCLUSION: Bacterial endocarditis is therefore a set of complex interactions between endothelial cells and bacteria which should be taken into consideration for the development of new therapeutic approaches.

Adult↗
PubMed2002

Luteal phase support using either Crinone 8% or Utrogest: results of a prospective, randomized study.

The Crinone 8% preparation makes it possible to administer natural progesterone (90 mg) vaginally once daily for luteal phase support (LPS). Until now, no prospective, randomized studies have directly compared this new preparation with widely used Utrogest capsules, which were originally designed for oral administration but are used routinely as a vaginal preparation. A prospective, randomized study investigated 126 patients undergoing cycles of in vitro fertilization (IVF) and IVF/intracytoplasmic sperm injection (ICSI). Patients received either Crinone 8% (n = 73) vaginally once daily or two Utrogest capsules (n=53) vaginally three times daily (600 mg). Clinical pregnancy rates were comparable (28.8 versus 18.9%), as were clinical abortion rates until 12 weeks of gestation (14.3 versus 10.0%) and clinical ongoing pregnancy rates (24.7 versus 17.0%) in the Crinone 8% and Utrogest groups, respectively. Forty-seven non-pregnant patients were randomly selected to answer questions regarding comfort during LPS. Crinone 8% had a clear advantage over Utrogest as it resulted in less vaginal discharge (P < 0.01) and fewer application difficulties (P<0.05). Twenty patients familiar with the alternative preparation from a previous cycle also noted that Crinone 8% was easier to apply (P < 0.01) and less time consuming (P < 0.05) to use than Utrogest.

Abortion, Spontaneous↗
PubMed2001

New surface biopolymers for oxygenators: an in vitro hemocompatibility test of poly(2-methoxyethylacrylate).

BACKGROUND/OBJECTIVE: The continuous interaction of blood with artificial contact surfaces under cardiopulmonary bypass can lead to a substantial damage of blood cells and plasma factors. Surface biopolymers in oxygenation systems can help increasing the hemocompatibility, often combined with anticoagulative agents such as heparin. The poly(2-methoxyethylacrylate) [PMEA] is a new heparin-free polymer. The objective of this experimental study was to evaluate the hemocompatibility of a PMEA-coated oxygenator (Terumo Capiox RX-25) (PTX) under standardized in vitro conditions compared to two ionic-bound and one covalent-bound heparin-coated models. METHOD: Each oxygenator was mounted in a separate standardized closed circulation system. Heparinized (5 IE/mL) fresh human blood from the same donor (hemodilution: Ringer's solution) was used. Circulation time: 120 - 180 min with a flow rate of 4.0 L/min. Blood samplings: at the beginning, 5. min and every 30 min of the circulation. PARAMETERS: platelets, granulocytes, plasma factors (p-selectin, alpha-granulomeres expression, and TAT(III)-complex). After the experiment, oxygenators were dismantled and examined by scanning electron microscopy. RESULTS: All of the oxygenators led to an initial reduction of platelets and granulocytes. PTX had the lowest platelet and granulocyte reduction rates. With a lower p-selectin release compared to covalent-bound heparin-coated oxygenator and higher expression of alpha-granulomeres compared to ionic-bound heparin-coated oxygenators, the results of PTX indicated that a high number of circulating platelets were intact on the PMEA surface. TAT(III)-complex showed a steady increase in all of the oxygenators during the tests, more remarkably in PTX. In contrast to ionic-bound heparin-coated oxygenators, the electron microscopy displayed virtually no cellular accumulation on hollow fiber and housing surfaces of PTX and covalent-bound heparin-coated oxygenator. CONCLUSIONS: 1. The hemocompatibility characteristics of PTX were remarkably better than ionic-bound heparin-coated oxygenators and slightly better than the covalent-bound heparin-coated model under in vitro conditions. 2. The PMEA coating can be a useful alternative for patients with heparin-associated disorders. 3. The clinical feasibility of PTX should be evaluated under in vivo conditions.

Acrylates↗
PubMed2001

The use of the L-plastin promoter for adenoviral-mediated, tumor-specific gene expression in ovarian and bladder cancer cell lines.

A 2.4-kb truncated L-plastin promoter was inserted either 5' to the LacZ gene (Ad-Lp-LacZ) or 5' to the cytosine deaminase (CD) gene (Ad-Lp-CD) in a replication-incompetent adenoviral vector backbone. Infectivity and cytotoxicity experiments with the LacZ and CD vectors suggested that the L-plastin promoter-driven transcriptional units were expressed at much higher levels in explants of ovarian cancer cells from patients and in established ovarian or bladder cancer cell lines than they were in normal peritoneal mesothelial cells from surgical specimens, in organ cultures of normal ovarian cells, or in the established CCD minimal deviation fibroblast cell line. Control experiments showed that this difference was not attributable to the lack of infectivity of the normal peritoneal cells, the normal ovarian cells, or the minimal deviation CCD fibroblast cell line, because these cells showed expression of the LacZ reporter gene when exposed to the replication-incompetent adenoviral vector carrying the cytomegalovirus (CMV)-driven LacZ gene (Ad-CMV-LacZ). The Ovcar-5 and Skov-3 ovarian cancer cell lines exposed to the Ad-Lp-CD adenoviral vector were much more sensitive to the prodrug 5-fluorocytosine (5FC), which is converted from the 5FC prodrug into the toxic chemical 5-fluorouracil, than was the CCD minimal deviation fibroblast cell line after exposure to the same vector. A mouse xenograft model was used to show that the Ad-Lp-CD vector/5FC system could prevent engraftment of ovarian cancer cells in nude mice. Finally, injection of the Ad-Lp-CD vector into s.c. tumor nodules generated a greater reduction of the size of the tumor nodules than did injection of the Ad-CMV-LacZ vectors into tumor nodules. The Ad-Lp-CD vectors were as suppressive to tumor growth as the Ad-CMV-CD vectors. These results suggest that an adenoviral vector carrying the CD gene controlled by the L-plastin promoter (Ad-Lp-CD) may be of potential value for the i.p. therapy of ovarian cancer.

Adenoviridae↗
PubMed2001

Migration of human granulocytes through reconstituted basement membrane is not dependent on matrix metalloproteinase-9 (MMP-9).

Transmigration of human granulocytes across a basal lamina equivalent was studied in vitro. Transwell inserts were coated with Matrigel, a reconstituted basement membrane. Granulocytes (2x10(6)) were applied to the upper chamber. As chemoattractant interleukin-8 (IL-8; 25 ng/ml) was added to the lower chamber. After 1 h of migration, cells were counted in the lower chamber. Specific hydroxamate inhibitors of MMPs (BB-3103, Ro 31-9790) or of serine proteases (Pefabloc, leupeptin) were added at various concentrations to both chambers before the start of migration. Additional experiments were performed with alpha(2)-macroglobulin, a natural inhibitor of MMPs and a monoclonal antibody which specifically blocks the activity of MMP-9. Migration of granulocytes through Matrigel could not be reduced significantly by any of the MMP inhibitors. A dose-dependent impairment of transmigration was only found with Pefabloc, however, this substance also induced severe morphological changes of the cells. The other inhibitor of serine proteases, leupeptin, did not influence migration at all.

Basement Membrane↗
PubMed2001

[Black nails caused by Proteus mirabilis].

Black nails caused by Proteus mirabilis were seen in a motor mechanic and in a petrol pump attendant. Proteus mirabilis is a gram-negative bacillus that generates hydrogen sulfide. This compound reacts with traces of metals in the nail plate such as zinc, nickel, cobalt, iron, manganese, tin, copper and lead. Metal sulfides blacken the nail plate. The protracted course of the discoloration over months corresponds to the slow reactions of metals with hydrogen sulfide. The disappearance of the blackening after topical treatment with chinosol, tincture of iodine and chloramphenicol solution supports the etiologic connection between black nails and Proteus mirabilis. Wet and dirty work encourages the colonisation of Proteus mirabilis between nail fold and nail plate.

Administration, Topical↗
PubMed2001

Lymphopenia in occupational pulmonary silicosis with or without autoimmune disease.

An increased prevalence of autoimmune diseases such as rheumatoid arthritis has been demonstrated in silica-exposed patients. The aim of this study was to determine the peripheral blood lymphocyte phenotype in a population of silicotic workers employed in the slate mines of the district. Silicosis was assessed in 58 patients according to the International Labor Office's criteria. Clinical and biological data including flow cytometric evaluation of the lymphocyte subsets were compared with those from 41 healthy volunteers. The silicotic patients had a higher prevalence of autoimmune diseases (6/58 versus 0/41: P < 0.05) and of elevated antinuclear antibody titres compared to the control group. A very significant decrease of total lymphocyte count (P < 0.001) involving B, T and Natural Killer cells was found in silicotic patients as compared with matched healthy volunteers. A significant increase in the percentage of activated T cells (12.3%) was observed in the silicotic group as compared to 6.5% in the control group (P = 5 x 10(-5)). Our results show that in silicotic patients, the absolute number of circulating lymphocytes is diminished with an increased proportion of activated T cells. Whether these findings could predispose to the development of autoimmune disorders is discussed.

Adult↗
PubMed2001

Use of microbeads for the detection of binding sites on the human zona pellucida: a scanning electron microscopy (SEM) assay.

One prerequisite for fertilization is the specific binding of spermatozoa to the zona pellucida. However, the factors and mechanisms involved in this gamete contact are not well understood. Gamete recognition and binding are species-specific and are controlled by oligosaccharides of the zona and their corresponding carbohydrates on the spermatozoon. By using a specific lectin we developed a technique to detect those oligosaccharides on the human zona pellucida that might be involved in the binding process. Microbeads (Ø = 2.8 microm), used as artificial spermatozoa, were coated with lectin Con A and cultured together with 75 unfertilized oocytes (group A) remaining after intracytoplasmic sperm injection. Con A binds specifically to alpha-d-mannose and alpha-d-glucose. As a control, 75 unfertilized oocytes after intracytoplasmic sperm injection (group B) were also cultured together with Con A-covered microbeads, but in a medium containing a binding inhibiting sugar (alpha-methyl-mannopyrasosid). The number and distribution of the microbeads on human oocytes of both groups were analysed on scanning electron microscopy images. Beads on oocytes of group A had binding patterns similar to those of spermatozoa. They were distributed in an extremely heterogeneous way with various numbers of bound beads both on individual and different oocytes. Most of the group A oocytes (85%) had more than 50 beads bound to the zona, in contrast to the control oocytes of group B, where 68% had less than 10 bound beads. The use of an inhibiting sugar abolished the binding capacity of the microbeads nearly completely. This technique is a powerful tool for the detection of binding sites on the zona pellucida, i.e. those sugars that are responsible for contact between spermatozoa and the zona pellucida.

Binding Sites↗
PubMed2001

Nonwoven fiber barriers for control of cabbage maggot and onion maggot (Diptera: Anthomyiidae).

We investigated the use of nonwoven fiber barriers for control of cabbage maggot, Delia radicum (L.), and onion maggot, D. antiqua (Meigen). The barriers consist of arrangements of minute fibers loosely intertwined in "web" form. Results from a greenhouse experiment showed that manually applied graphite fibers placed at the base of broccoli plants reduced the number of D. radicum eggs by 64-98%, and that efficacy increased with greater fiber density. Using a melt extrusion process, we devised a method for on-site creation of nonwoven fibers of ethylene vinyl acetate (EVA). In field trials with broccoli and onion plants, EVA fibers significantly reduced the number of cabbage and onion maggots infesting plants. Fiber barriers provided comparable control to standard insecticide applications. The addition of blue, yellow, red, or black pigments, as well as optical brighteners that absorb UV light did not enhance fiber efficacy. Incorporation of capsaicin olfactory repellent to EVA also did not enhance fiber efficacy. Nonwoven fiber barriers may offer an alternative to insecticides for control of cabbage maggot and onion maggot and possibly other insect pests. Additional research is needed to improve the application process and to identify economically feasible and biodegradable compounds for fibers.

Animals↗
PubMed2001

Prospective, randomized study to evaluate the success rates using hCG, vaginal progesterone or a combination of both for luteal phase support.

BACKGROUND: A prospective study was done to compare the efficacy of luteal phase support (LPS) using either three times hCG (group I, n=77), hCG on the day of embryo transfer (ET) in combination with daily vaginal progesterone (group II, n=62) or vaginal progesterone only (group III, n=70). METHOD: All patients were treated using the long luteal protocol for controlled ovarian stimulation in an IVF (in vitro fertilization) cycle. Patients were randomized to one of these groups when estradiol was <2500 pg/ml and less than 12 oocytes were retrieved (low risk groups). If estradiol was > or = 2500 pg/ml and/or at least 12 oocytes were retrieved (high risk groups), patients were randomized to receive either hCG in combination with daily vaginal progesterone (group IV, n=83) or progesterone only (group V, n=121). For vaginal progesterone Utrogest was used (three times daily two capsules containing 100 mg progesterone, 600 mg/d). RESULTS: Demographic data were comparable within the high risk and low risk groups. However, for unknown reasons the fertilization rate was significantly higher in group V (48%) compared to group IV (40%) (p<0.05), leading to a significantly higher cumulative embryo score. There were no statistically significant differences with regard to the main outcome parameter, the clinical ongoing pregnancy rate in the low risk groups (14.3%, 14.5%, 11.4%) and the high risk groups (21.0%, 21.5%), respectively. Using a standardized discomfort scale, there were more complaints towards the end of the luteal phase in the groups receiving hCG only or an additional injection of hCG, when compared to the progesterone only groups. CONCLUSION: Progesterone only for luteal phase support leads to the same clinical ongoing pregnancy rate as hCG, but has no impact on the comfort of the patient.

Administration, Intravaginal↗
PubMed2000

Myelin basic protein induces cell death of mature pig oligodendrocytes in vitro and produces demyelination in vivo.

Two methods prevail at present in producing demyelinated areas in the central nervous system. One uses the detergent-like effect of lysolecithin, the other is based on a cell killing effect of ethidium bromide plus x-irradiation. Unwanted side-effects are inherent in both methods. Based on the fact that myelin basic protein (MBP) kills adult pig oligodendrocytes but almost no astrocytes in vitro, we have used MBP for creating demyelinated areas in the centrum semiovale of the pig brain. These lesions are characterized by a loss of oligodendrocytes and myelin, a preservation of axons and astrocytes, and by the presence of macrophages. Thus, this type of lesion might present an alternative option for studying the fate of transplanted myelinating cells.

Animals↗