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Biomedical subjects

P Lenz

Publications and source records attributed to P Lenz.

At least 19 recordsLinked to original sources
PubMed2005

Mosaic status in lymphocytes of infertile men with or without Klinefelter syndrome.

BACKGROUND: Gonosomal aneuploidies such as Klinefelter syndrome (47,XXY) are the most frequent chromosomal aberration in infertile men. Normally the chromosomal status of patients is detected by karyotyping of up to 20 metaphase spreads of lymphocyte nuclei, whereby low grade mosaicism may be overlooked. To test whether Klinefelter patients with 47,XXY karyotype or infertile men with 46,XY karyotype represent gonosomal mosaicisms, we performed meta- and interphase fluorescence in situ hybridization (FISH) on 45 men. METHODS AND RESULTS: A total of 400 interphase and 40 metaphase lymphocyte nuclei per patient were scored after hybridization with DNA probes specific for chromosomes X and Y, and chromosome 9 as a control. On the basis of conventional karyotype, hormone levels and clinical appearance, patients were subdivided into 18 Klinefelter syndrome patients with 47,XXY (group I), 11 Klinefelter syndrome-like patients with normal karyotype, 46,XY (group II) and six non-Klinefelter-like infertile patients with normal 46,XY karyotype (group III). Ten normal men (group IV) served as controls. Testicular volume in the Klinefelter group I was smaller compared with group II (P = 0.016), group III (P < 0.001) and group IV (P < 0.001). In addition, testicular volumes in group II were lower compared with group III and group IV (P < 0.004). No significant differences between the aneuploidy rate analysed by FISH in interphase nuclei and metaphases were found in either single patients or groups. Patients with Klinefelter syndrome, 47,XXY (group I) or with symptoms similar to those in Klinefelter patients 46,XY (group II) showed a similar aneuploidy rate (group I 7.1 +/- 4.0% and group II 4.6 +/- 3.4%) and two 47,XXY patients with a high prevalence for normal 46,XY lymphocytes had sperm in their ejaculate. However, in general, no correlations between FISH mosaic status and serum hormone parameters, nor with ejaculate parameters were found. CONCLUSIONS: The results suggest that 47,XXY patients with an increased incidence of XY cells (average of 4.2 +/- 2.3) may have a higher probability of germ cells as we found sperm only in the ejaculate of Klinefelter syndrome patients with mosaic 46,XY cells (6.0 and 7.0%). On the other hand, 46,XY patients with mosaic sex chromosome aneuploidies detected by FISH analysis more often show symptoms of hypogonadism phenotypically resembling Klinefelter syndrome.

Adult↗
PubMed2004

Periodic adhesive fingers between contacting cells.

We study in detail the properties of fingers, a particular type of cell-cell adhesive structures appearing in adherens junctions. These periodic patterns break the symmetry of cell-cell contacts. We show that finger formation is driven by cadherin interactions and actin growth. A theoretical model is introduced in which the growth of fingers is limited by membrane tension. The steady shape and formation kinetics of fingers are experimentally measured and compared with the theoretical predictions.

Actin Cytoskeleton↗
PubMed2004

In vitro investigation of marginal accuracy of implant-supported screw-retained partial dentures.

Mismatch occurring during the fabrication of implant-supported dentures may induce stress to the peri-implant bone. The purpose of this study was to investigate the influence of two different alloys and the fabrication method on the marginal accuracy of cast partial dentures. Two laboratory implants were bonded into an aluminium block so that the distance between their longitudinal axes was 21 mm. Frameworks designed for screw-retained partial dentures were cast either with pure titanium (rematitan) or with a CoCr-alloy (remanium CD). Two groups of 10 frameworks were cast in a single piece. The first group was made of pure titanium, and the second group of a CoCr-alloy (remanium CD). A third group of 10 was cast in two pieces and then laser-welded onto a soldering model. This latter group was also made of the CoCr-alloy. All the frameworks were screwed to the original model with defined torque. Using light microscopy, marginal accuracy was determined by measuring vertical gaps at eight defined points around each implant. Titanium frameworks cast in a single piece demonstrated mean vertical gaps of 40 microm (s.d. = 11 microm) compared with 72 microm (s.d. = 40 microm) for CoCr-frameworks. These differences were not significant (U-test, P = 0.124) because of a considerable variation of the values for CoCr-frameworks (minimum: 8 microm and maximum: 216 microm). However, frameworks cast in two pieces and mated with a laser showed significantly better accuracy in comparison with the other experimental groups (mean: 17 microm +/- 6; P < 0.01). (i) The fit of implant-supported partial dentures cast with pure titanium in a single piece is preferable to that of those made with the CoCr-alloy and (ii) the highest accuracy can be achieved by using a two-piece casting technique combined with laser welding. Manufacturing the framework pieces separately and then welding them together provides the best marginal fit.

Bone Screws↗
PubMed2004

Membranes with rotating motors: microvortex assemblies.

We study collections of rotatory motors confined to 2-dimensional manifolds. The rotational motion induces a repulsive hydrodynamic interaction between motors leading to a non-trivial collective behavior. For high rotation speed, motors should arrange on a triangular lattice exhibiting crystalline order. At low speed, they form a disordered phase where diffusion is enhanced by velocity fluctuations. In confining geometries and under suitable boundary conditions, motor-generated flow might enhance left-right symmetry-breaking transport. All these effects should be experimentally observable for motors driven by external fields and for dipolar biological motors embedded into lipid membranes in a viscoelastic solvent.

Adenosine Triphosphatases↗
PubMed2001

Hexatic order and surface ripples in spherical geometries.

In flat geometries, two-dimensional hexatic order has only a minor effect on capillary waves on a liquid substrate and on undulation modes in lipid bilayers. However, extended bond-orientational order alters the long-wavelength spectrum of these ripples in spherical geometries. We calculate this frequency shift and suggest that it might be detectable in lipid bilayer vesicles, at the surface of liquid metals, and in multielectron bubbles in liquid helium at low temperatures. Hexatic order also leads to a shift in the threshold for the fission instability induced in the later two systems by an excess of electric charge.

Journal Article↗
PubMed2001

Papillomavirus-like particles induce acute activation of dendritic cells.

The role of viral structural proteins in the initiation of adaptive immune responses is poorly understood. To address this issue, we focused on the effect of noninfectious papillomavirus-like particles (VLPs) on dendritic cell (DC) activation. We found that murine bone marrow-derived dendritic cells (BMDCs) effectively bound and rapidly internalized bovine papillomavirus VLPS: Exposure to fully assembled VLPs of bovine papillomavirus, human papillomavirus (HPV)16 or HPV18, but not to predominately disordered HPV16 capsomers, induced acute phenotypic maturation of BMDCS: Structurally similar polyomavirus VLPs bound to the DC surface and were internalized, but failed to induce maturation. DCs that had incorporated HPV16 VLPs produced proinflammatory cytokines IL-6 and TNF-alpha; however, the release of these cytokines was delayed relative to LPS activation. Production of IL-12p70 by VLP-exposed DCs required the addition of syngeneic T cells or rIFN-gamma. Finally, BMDCs pulsed with HPV16 VLPs induced Th1-dominated primary T cell responses in vitro. Our data provide evidence that DCs respond to intact papillomavirus capsids and that they play a central role in VLP-induced immunity. These results offer a mechanistic explanation for the striking ability of papillomavirus VLP-based vaccines to induce potent T and B cell responses even in the absence of adjuvant.

Animals↗
PubMed2001

Color stability of highly filled composite resin materials for facings.

OBJECTIVES: The aim of the investigation was to examine the color stability of seven resin-based facing composites with a high content of inorganic filling material (Colombus, Artglass, Sinfony, Targis, Zeta LC, Zeta HC, BelleGlass HP/dentine, BelleGlass HP/enamel). METHODS: Changes in color of test samples were determined after UV irradiation in a fast-action UV instrument, Sunset CPS+, and after storage in a mouthrinse, tea, coffee, red wine and a 0.1% turmeric (curcuma) solution. Color differences were measured by using a Castor colorimeter and the total amount of color difference represented as DeltaE. RESULTS: Red wine and the turmeric solution caused the most severe cases of discoloration (DeltaE>10). Tea, coffee, the mouthrinse and UV irradiation caused invisible (DeltaE<1) or visible (DeltaE>1), and to some extent clinically unacceptable (DeltaE>3.3), discoloration. SIGNIFICANCE: It is apparent from the results that it remains essential to improve the color stability of the composite resin materials used for facings.

Color↗
PubMed2001

Enhancement of delta aminolevulinic acid-photodynamic therapy in vivo by decreasing tumor pH with glucose and amiloride.

OBJECTIVES/HYPOTHESIS: Delta aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) is a fluorescent sensitizer that permits detection and treatment of squamous cell carcinoma of the oral cavity. An exogenously induced decrease in tissue pH was evaluated for its effect in enhancing cellular uptake of ALA and facilitating its transformation into PpIX. STUDY DESIGN: Mice grafted with HT29 colonic cancers had been given glucose and amiloride to modify the pH of tissues. Influence of pH changes has been evaluated on ALA-induced PPIX fluorescence by optic fiber spectrofluorimetry as well as on tumor growth. METHODS RESULTS: The pH in HT 29 tumor decreased from 7.1 to 6.67 (P < .05) after intraperitoneal injection of glucose and amiloride. The PpIX fluorescence ratios in tumor or muscle before, between, and 2 hours after glucose and amiloride injection were not higher than control ratios. Aminolevulinic acid-photodynamic therapy was more efficient on HT 29 tumor-bearing mice when the pH value was decreased with glucose and amiloride, showing a difference in the tumor growth index ratio from the 1st to 14th day of 22% between amiloride-glucose aminolevulinic acid-photodynamic therapy and aminolevulinic acid-photodynamic therapy alone (P < .05). CONCLUSIONS: Glucose and amiloride did not change PpIX fluorescence in HT 29 tumor after intraperitoneal injection of aminolevulinic acid but enhanced aminolevulinic acid-photodynamic therapy efficacy. This was probably a result of mechanisms other than an increase in aminolevulinic acid cellular penetration and PpIX production, such as susceptibility to free radical toxicity or alteration of cellular repair enzymes under acidotic conditions. If a decrease of pH induces a more efficient photodynamic therapy as suggested by our results, an easier way to obtain this decrease than glucose and amiloride would be necessary for clinical applications.

Acid-Base Equilibrium↗
PubMed2001

Highly active antiretroviral therapy responders exhibit a phenotypic lymphocyte pattern comparable to that of long-term nonprogressors.

BACKGROUND: The implementation of highly active antiretroviral therapy (HAART) in patients with progressive HIV-1 disease has resulted in a marked reduction of HIV-1-associated morbidity and mortality. In fact, the risk of HAART responders to develop opportunistic infections becomes similar to that of long-term nonprogressors (LTNPs). METHODS: Reasoning that HAART may ultimately have consequences on both the quantity and quality of immune responses of a HIV-1-infected person, we assessed CD4+ and CD8+ T cell subsets in HAART recipients over a time period of 15 months and compared them to the lymphocyte phenotype of LTNPs and healthy controls. Evaluations included quantitative determinations of memory (CD45RO+CD62L-), naive (CD45RO-CD62L+), effector (CD27-, CD28-) and activated (HLA-DR+, CD38+, CD95+) CD4+ and CD8+ lymphocytes. The T cell function was assayed by skin tests. RESULTS: Compared to healthy persons, treatment-naive patients with progressive disease exhibited a considerable reduction of CD4+ T cells with many of the remaining T cells showing signs of activation at baseline. CD8+ T cells were greatly increased in number, mainly because of an expansion of CD28- effector and memory CD8+ T cells. LTNPs, in contrast, had stable CD4+ and elevated CD8+ T cell counts, the latter being mainly due to a marked increase in CD27- effector cells. Essentially, the same immunophenotype was seen in HAART responders after 15 months of treatment when compared to LTNPs. CONCLUSIONS: It is tempting to speculate that a HAART-induced reduction in viral load may influence the immune system's capacity to mount protective responses to pathogenic microorganisms.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Liquid morphologies on structured surfaces: from microchannels to microchips

Liquid microchannels on structured surfaces are built up using a wettability pattern consisting of hydrophilic stripes on a hydrophobic substrate. These channels undergo a shape instability at a certain amount of adsorbed volume, from a homogeneous state with a spatially constant cross section to a state with a single bulge. This instability is quite different from the classical Rayleigh Plateau instability and represents a bifurcation between two different morphologies of constant mean curvature. The bulge state can be used to construct channel networks that could be used as fluid microchips or microreactors.

Journal Article↗
PubMed1999

Desmoglein 3-ELISA: a pemphigus vulgaris-specific diagnostic tool.

BACKGROUND: Pemphigus vulgaris (PV) is an autoimmune-blistering disease of the skin and mucous membranes caused by autoantibodies against desmoglein 3 (Dsg3), an epidermal desmosomal adhesion protein of the cadherin family. Cloning of the Dsg3 gene and expression of the protein in a native conformation enabled the recent development of a specific and sensitive enzyme-linked immunosorbent assay (ELISA) for the detection of PV autoantibodies. OBJECTIVES: To evaluate serum samples from patients with PV and other dermatologic diseases for anti-Dsg3 antibodies. To compare ELISA values with autoantibody titers obtained by classic indirect immunofluorescence (IIF). DESIGN: Serum samples from patients with PV and various other bullous and nonbullous skin diseases were tested for anti-Dsg3 reactivity by ELISA. SETTING: Ambulatory and hospitalized patients from a university hospital. PATIENTS: Fifty-two serum samples from 11 patients with PV, and serum samples from 11 patients with bullous pemphigoid, 12 patients with other bullous diseases, 22 patients with various nonbullous skin disorders, and 10 healthy individuals were tested. RESULTS: Forty-seven (98%) of 48 serum samples from patients with PV that were positive by IIF on monkey esophagus were also reactive by Dsg3-ELISA, whereas 4 of 4 IIF-negative PV serum samples showed no reactivity by ELISA. In addition, negative ELISA results were obtained from 11 of 11 serum samples from patients with bullous pemphigoid, 10 of 12 serum samples from patients with other bullous skin disorders, 7 of 9 serum samples from patients with autoimmune-connective tissue diseases, and 13 of 13 serum samples from patients with other nonbullous skin diseases. Interestingly, 1 patient with paraneoplastic pemphigus had positive ELISA results. There was a positive correlation (r = 0.654) between ELISA values and IIF titers within the whole population with PV. In addition, when multiple serum samples from 1 patient with PV sampled over a 2-year period were tested, ELISA reactivity paralleled both the IIF titers and the clinical course. CONCLUSION: The Dsg3-ELISA is a sensitive, objective, and PV-specific test that should be considered as an adjunct test for the management of patients with PV.

Adult↗
PubMed1998

[Cicatricial pemphigoid with autoantibodies to laminin 5 (epiligrin) in a patient with metastatic endometrial carcinoma].

A 71-year-old female patient presented with erosions of the oral, genital and ocular mucosa, but without skin lesions. One year prior to the onset of lesions, a metastatic adenocarcinoma of the endometrium had been diagnosed. In perilesional skin, direct immunofluorescence showed linear deposits of C3 and IgG along the basement membrane zone. Indirect immunofluorescence demonstrated anti-basement membrane zone antibodies which bound exclusively to the dermal side of 1M NaCl-split skin. In immunoprecipitation studies, the autoantibodies bound a set of proteins characteristic of epiligrin/laminin-5, and they specifically immunoblotted the alpha-subunit of this protein. These results confirmed our presumed diagnosis of anti-epiligrin cicatricial pemphigoid. Combined treatment with methylprednisolone and dapsone resulted in prompt remission, despite progression of her malignancy. So far, only eight patients with anti-epiligrin cicatricial pemphigoid have been reported worldwide. Our patient represents the first case from Austria and is clinically and immunopathologically similar to previously reported cases.

Adenocarcinoma↗
PubMed1997

In vitro and in vivo spectrofluorometry of a water-soluble meta-(tetrahydroxyphenyl)chlorin (m-THPC) derivative.

The pharmacokinetics of a water-soluble derivative obtained from meta-(tetrahydroxyphenyl)chlorin (m-THPC) was evaluated in in vitro and in vivo studies. Cytoplasm fluorescence was measured in two cell models (L1210 and HT29) using a flow cytometer and a confocal microspectrofluorometer. Cells were incubated with the compound at several doses (0-150 micrograms ml-1 for flow cytometry) and for several time periods (0-6 h for microspectrofluorometry). For in vivo studies, nude mice were grafted with human adenocarcinoma 15 days before intraperitoneal injection of polyethylene glycol-m-THPC (PEG-m-THPC). Fluorescence was recorded through an optical fibre spectrofluorometer using the 660 nm peak for detection. In in vitro studies, the fluorescence was found to be proportional to the dose. Maximum fluorescence was recorded in L1210 cells earlier and more intensely than in HT29 cells (3 h at 202 +/- 14 counts s-1 and 5 h at 43 +/- 2.15 counts s-1 respectively). Concerning in vivo studies, maximum tumour fluorescence was observed 24 h after injection (3568 +/- 178 counts s-1). Selectivity was expressed by the calculated tumour-to-skin and tumour-to-muscle ratios. The time taken to observe the maximum ratios (2.95 +/- 0.16 for tumour-to-skin and 6.61 +/- 0.3 for tumour-to-muscle) was almost the same as the time taken to observe the maximum fluorescence in the tumour. Studies are in progress to correlate these results with photodynamic effects.

Animals↗
PubMed1996

A portable absorption-fluorometer for detection of organic substances in fluids.

Using the method of multipath-saturation fluorescence, which considers both fluorescent as well as nonfluorescent substances, the total absorption coefficient can be determined with high sensitivity. This new fluorescence method is appropriate, e.g. for in-situ applications. Thus a portable absorption-fluorometer has been constructed. The main part of the device is a multireflection cell based on a design of Herriott with a 1 cm quartz-cuvette. Two pairs of spherical dielectric mirrors are used to realize the multireflection of the excitation radiation in the UV and blue spectral range. The combination of a cylindrical and a convace mirror leads to a long pathway of the excitation radiation and, thus, to a full absorption by the fluid. A first experiment has been performed with drinking water samples defined polluted by non-fluorescent p-nitrophenol and 2-nitroaniline. Based on the method of multipath-saturation fluorescence a good correlation to the substance concentration was achieved, whereas the conventional absorption failed.

Journal Article↗
PubMed1996

Fc gamma-receptor III (CD 16) is involved in NK-B cell interaction.

CD16, the low affinity receptor for monomeric IgG (Fc gamma RIIIA), is a well characterized activation molecule on NK cells. In this study we investigated the role of CD16 in NK cell-mediated regulation of immunoglobulin production. Cocultures of the CD16+ human NK clone CNK6 and highly purified SAC/IL-2-activated B lymphocytes with various CD16 antibodies showed significantly diminished NK-enhanced immunoglobulin production in a dose-dependent manner, indicating that CD16 is relevant in NK-B cell interaction. Similarly, recombinant soluble CD16 incubated with B cells before cultures, suppressed the NK cell-stimulated B cell antibody response. Enhanced immunoglobulin production was also inhibited by Fc-specific F(ab')2 anti-body fragments. Coculture of NK cells with B lymphocytes resulted in induction of mRNA for IFN-gamma and TNF-alpha. The accumulation of mRNA for these cytokines was prevented by addition of CD16 and Fc-specific antibodies. It is proposed that interaction of CD16 on NK cells with B cell bound immunoglobulin leads to induction of cytokines in NK cells which stimulate immunoglobulin production by B cells.

Antibodies, Monoclonal↗
PubMed1996

MHC class I expression on dendritic cells is sufficient to sensitize for transplantation immunity.

The immunogenicity of an allograft correlates with the number of MHC class II+ antigen-presenting cells (dendritic cells) that it contains. To determine whether these antigen-presenting cells induce not only MHC class II-mediated immune responses, but also physiologically relevant levels of MHC class I immunity, we took advantage of a unique MHC class I+/class II-/CD80+ dendritic cell line (80/1 DC) derived from murine (C3H, H-2k) fetal skin. The 80/1 DC sensitized H-2-disparate recipients for specific transplantation immunity, as evidenced by significantly accelerated rejection (second set) of skin allografts from C3H mice, but not of third-party allografts. As few as 10(2) 80/1 DC, administered by the subcutaneous route, were effective, indicating their high potency as stimulator cells. Several lines of evidence support the hypothesis that the immunization observed was mediated primarily by direct presentation of allo-class I: (i) Blockage of the co-stimulatory molecule CD80 on 80/1 DC abrogated their sensitizing capacity; (ii) equal numbers of a nonprofessional antigen-presenting cell line (L929, C3H origin) as well as dead 80/1 DC failed to accelerate graft rejection; and (iii) injection of syngeneic (BALB/c) Langerhans cells pulsed with 80/1 DC fragments induced a delayed-type hypersensitivity reaction to these fragments but failed to accelerate rejection of C3H skin grafts. We conclude that direct allo-class I immunity can occur in the absence of class II expression when induced by a professional antigen-presenting cell and that this mechanism has biologic relevance in transplantation immunity.

Animals↗
PubMed1995

Correlation between meta(tetrahydroxyphenyl)chlorin (m-THPC) biodistribution and photodynamic effects in mice.

Analysis of sensitizer kinetics is essential for the performance of light irradiation when tumour concentration and tumour-to-normal tissue ratios are optimal. In this study nude mice were grafted with human adenocarcinoma 15 days before meta(tetrahydroxyphenyl)chlorin (m-THPC) intra-peritoneal (IP) injection. Fluorescence was recorded through an optic fibre spectrofluorometer at 650 (the most intense) and 714 nm, with intensity being proportional to injected dose. In tumour, skin and muscle the maximum fluorescence was obtained with 1.6 mg kg-1 72 h after injection (44 counts per second). Tumour-to-skin and tumour-to-muscle ratios obtained by high performance liquid chromatography (HPLC) analysis and spectrofluorometric measurements decreased between 12 and 72 h (from 15 to 1.5), indicating that tumour selectivity decreases with time. This contrast between selectivity and fluorescence levels was also observed with photodynamic therapy (PDT) results, for which no differences were observed when 10 J cm-2 were delivered at 100 or 200 mW. PDT results were better 24 h after drug administration than at 72 h. Tumour growth decrease (-40%) was found when 1.6 mg kg-1 were injected 24 h before irradiation. For other groups a slower increase (12% vs. 23%) was noted in the first few days after PDT. The paradoxal correlation between fluorometric or HPLC measurements and PDT effects suggests that m-THPC localizes differently with time in tumour components.

Adenocarcinoma↗