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Biomedical subjects

A Ziegler

Publications and source records attributed to A Ziegler.

At least 253 records · Page 14Linked to original sources
PubMed1991

Isolation of probes specific to human chromosomal region 6p21 from immunoselected irradiation-fusion gene transfer hybrids.

A hybrid cell line (R21/B1) containing a truncated human chromosome 6 (6pter-6q21) and a human Y chromosome on a hamster background was irradiated and fused to A23 (TK-) or W3GH (HPRT-) hamster cells. Clones containing expressed HLA class I genes (4/40) were selected using monoclonal antibodies. These clones were recloned and analyzed with a panel of probes from the HLA region. One hybrid (4G6) contained the entire HLA complex. Two other hybrids (4J4 and 4H2) contained only the HLA class I region, while the fourth hybrid (5P9) contained HLA class I and III genes in addition to other genes located in the 6p21 chromosomal region. In situ hybridization showed that the hybrid cells contained more than one fragment of human DNA. Alu and LINE PCR products were derived from these cells and compared to each other as well as to products from two somatic cell hybrids having the 6p21 region in common. The PCR fragments were then screened on conventional Southern blots of the somatic cell hybrids to select a panel of novel probes encompassing the 6p21 region. In addition, the origin of the human DNA fragments in hybrid 4J4 was determined by regional mapping of PCR products.

Animals↗
PubMed1991

Evaluation of the acrosome reaction using monoclonal antibodies against different acrosomal antigens--comparison with the triple stain technique.

The acrosome reaction of human sperm was evaluated in vitro with the aid of there monoclonal antibodies TüS-1, TüS-19 and TüS-20, which react with antigens in the anterior part of the acrosome. Data were compared with results obtained using the triple stain technique. Seminal smears were performed prior to, and following incubation for 5 and 24 h in Hams-F10 containing 3% human serum albumin. Using the triple stain technique, 15.2 +/- 7.1% of sperm exhibited acrosome activation after 5 h and 16.8 +/- 8.4% after incubation for 24 h. The corresponding values obtained using antibody TüS-1 were 12.9 +/- 5.8 and 13.2 +/- 2.2%, with TüS-19 10.1 +/- 3.8 and 10.8 +/- 1.4% and with TüS-20, 9.0 +/- 3.4 and 10.4 +/- 2.9%. When the same sperm smears were stained firstly with rose Bengal, and secondly with TüS-1 both methods stained the same cells and the same region of the cells, thus indicating that both methods stain the same substrate. Staining of the acrosome with monoclonal antibodies gives clearer results than the triple stain technique, and could be used in preference in future studies dealing with diagnosis of the acrosome reaction in vitro.

Acrosome↗
PubMed1991

Investigations into the pharmacodynamic effects of dermally administered microemulsions containing beta-blockers.

Water uptake from the skin changes dermally applied near-saturated solutions of beta-blockers in microemulsion-bases into supersaturated microemulsions. Due to an enhanced thermodynamic activity, high absorption rates are expected from these preparations. The pharmacodynamic effect after dermal administration of such preparations has been evaluated using rabbits as a suitable in-vivo model. The dose dependency, influence of lipophilicity and of the thermodynamic activity of the drug is described. Assessment of dermal doses which were therapeutically equivalent to i.v. doses as, for example, shown with carazolol is possible. Although not all observed pharmacodynamic effects were due to these influences but rather due to the numerous other skin-vehicle-drug interactions which could not be explained with this model, the presented in-vivo model is helpful in evaluation of beta-blockers which were suitable candidates for transdermal administration.

Administration, Cutaneous↗
PubMed1991

Pharmacodynamic effects of transdermal bupranolol and timolol in vivo: comparison of microemulsions and matrix patches as vehicle.

Transdermal administration of drugs possesses several advantages in therapy, but is limited by generally poor penetration through the skin. The aim of this study was to assess whether in vivo transdermal absorption could be enhanced by using microemulsions (ME) as vehicles. Water uptake from the occluded skin changes the water-free microemulsion base (MEB) into a ME. The increasing content of water decreases the solubility of apolar drugs. This leads to in situ formation of a super-saturated ME that possesses a particularly high absorption rate due to the enhanced diffusion pressure of the drug. A saturated solution of the model drugs bupranolol (B) and timolol (T) in a water-free microemulsion base was applied to an clipped area of the dorsal skin of rabbits with an occlusive patch. Evaluations were made in comparison to matrix patches (M) containing 1.2 mg/cm2 B or 2.0 mg/cm2 T. The beta-blocker dose applied was 2.0 mg/kg body weight throughout the study. The measured parameter of the pharmacodynamic effect was the maximal heart rate (HR) after an i.v. bolus injection of a standard dose of isoproterenol. Observations were made in different intervals over a 10-h time period after application of the patches. The response to isoproterenol was calculated as beta-blocker effect. Faster increasing effects and higher maxima for both drugs was found after application in MEB compared to M. After administration of B and T in MEB the effects were found to be identical, with a maximum (85-90%) after 2 h. Application in M showed B to be less effective (34%, 10h no plateau) than T (74%, 10h). Therefore microemulsions represent an improved vehicle for transdermal administration of test drugs.

Administration, Cutaneous↗
PubMed1990

Ca2+ potentiates cAMP-dependent expression of urokinase-type plasminogen activator gene through a calmodulin- and protein kinase C-independent mechanism.

In the porcine renal epithelial cell line, LLC-PK1, activation of the cAMP-dependent signal transduction pathway induces the urokinase-type plasminogen activator (uPA) gene. We show here that the cAMP response is enhanced when the intracellular calcium concentration is increased. When LLC-PK1 cells were treated with the calcium ionophore ionomycin alone, there was no uPA mRNA accumulation. However, in the presence of ionomycin the dose-response of 8-bromo-cAMP (Br-cAMP) with respect to uPA mRNA accumulation was shifted toward the lower concentrations of Br-cAMP. A Northern blot analysis after the inhibition of RNA synthesis and nuclear run-on assays showed that the synergistic effect of Ca2+ could be attributed to increases in uPA gene transcription and mRNA stability. In the presence of cycloheximide, a protein synthesis inhibitor, uPA mRNA was stabilized, but the effect of ionomycin on Br-cAMP-induced mRNA accumulation was still maintained. The result suggests that the Ca2+, at least on transcription, does not require new protein synthesis. Ionomycin treatment did not modify the activity of the cAMP-dependent protein kinase, suggesting that Ca2+ either affects a step in the pathway between the kinase and the uPA gene, or acts independently of the cAMP-dependent protein kinase pathway. The effect of ionomycin was not suppressed by protein kinase C down-regulation nor by inhibitors of calmodulin. Synergism was also observed when Br-cAMP was replaced with calcitonin, a peptide hormone which is coupled to adenylate cyclase, and when ionomycin was replaced with another ionophore A23187, suggesting that the synergism is due to an interaction between cAMP-dependent and Ca2(+)-dependent signal transduction pathways.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1990

Evidence for light-induced release of Ca2+ from intracellular stores in bee photoreceptors.

In the drone retina light elicits an increase in the extracellular Ca2+ concentration ([Ca]o). After withdrawal of extracellular Ca2+ and addition of 1 mM EGTA (ethyleneglycol-bis (beta-aminoethyl ether) N,N,N',N'-tetraacetic acid) a short light flash still caused an increase in [Ca]o as measured with Ca2(+)-sensitive microelectrodes. This increase vanished after a few flashes. When [Ca]o was reduced to 10(-5) M Ca2+ (no EGTA) the rise in Cao disappeared after several light flashes. Subsequent stimulation with a dim steady light produced a decrease in [Ca]o and caused a recovery of the increase in [Ca]o elicited by a test flash. The results show that bee photoreceptors have a light-depletable intracellular Ca2+ store which can be reloaded by dim continuous lights.

Animals↗
PubMed1990

Immunoelectron microscopy of human spermatozoa.

A number of immunocytochemical methods using various markers for electron microscopy have been developed in recent years. The immunogold technique has been especially effective in histotopochemical studies. The value of this technique for demonstrating sperm antigens results from the high electron density of gold, which makes it easily detectable under the electron microscope. The high resolution of the electron microscope permits precise localization of immunologic reactions in the sperm cell. Light microscopy findings can thus be elucidated. We tested a number of monoclonal antibodies that react with sperm antigens. Of three techniques for preparing the spermatozoa, the pre-embedding method and marking of cryoultra-microtome sections proved best.

Fluorescent Antibody Technique↗
PubMed1990

Monoclonal antibodies against antigens expressed by human sperm.

The production and characterization of 21 mouse monoclonal antibodies (TüS1-TüS21) with specificity predominantly for human spermatozoa antigens is described. Reactivity of cells from human ejaculates, peripheral blood and several organs was determined using the alkaline phosphatase-anti-alkaline phosphatase (APAAP)-technique as well as the indirect immunofluorescence test. 15 of the monoclonal antibodies reacted with various regions of human sperm and often also with their precursor cells in the testis. Cross-reactivity with animal spermatozoa was frequently observed.

Acrosome↗
PubMed1990

Morphometry and function of islet cells after different forms of drainage at pancreatic transplantation in rats.

The survival of endocrine cells of the islets is crucial for a successful transplantation of the pancreas in the treatment of diabetes mellitus. In the present investigation, we compared the effect of four techniques of whole pancreas transplantation in rats on the endocrine cells of islets of Langerhans. Impairment of the endocrine function of the pancreas with a decrease in the k value was seen after 6 months in the group with duct ligation, and after 12 months in the groups with latex and ethibloc occlusion. An open pancreatic duct maintains a more stable endocrine function than in duct-ligated or occluded grafts. Fasting plasma insulin and somatostatin were elevated in transplanted rats. Whichever method of transplantation we chose, the cell ratio remained unchanged compared with the control group, even after 12 months. Therefore, only intact islet architecture enables a normal endocrine pancreatic function.

Animals↗
PubMed1990

[Sperm detection using monoclonal antibodies].

Monoclonal antibodies against sperm antigens detect specifically seminal stains in forensic casework. Different monoclonal antibodies resulting from the hybridoma technique allow by means of peroxidase test-system a direct marking of the trace.

Antibodies, Monoclonal↗
PubMed1990

[Risk profile and macroangiopathy in type II diabetics in medical practice].

The risk profile and the macro-vascular complications of patients with type II diabetes mellitus (NIDDM) was investigated in general practice patients for the first time in the FRG. It was the aim of the study to evaluate the efficacy of the therapy and possible improvements after detailed instructions in a random sample of well defined NIDDM in the greater Munich area. 290 NIDDM (187 female, 103 male) out of a total of 1500 patients treated by 22 general practitioners were randomly recruited for the study. First results indicated an excess morbidity of the NIDDM, e.g. 43.5% with HbA1c greater than 8%, hypertension in 73.8%, hypertriglyceridemia in 75%, hypercholesterolemia in 36.3% adipositas in 78%, and a micro/macro-albuminuria in 44.5%. A similar risk profile could be determined in cases with recently diagnosed NIDDM. The remarkable risk profile documents itself in the incidence of macro-vascular complications: 40.8% of the male and 43.2% of the female showed a peripheral arterial disease (pAVD), in 8% of all patients a carotid artery stenoses could be detected by means of doppler ultrasound technique; 46.6% of the male and 59.3% of the female patients showed symptoms of CHD. With the exception of the incidence of CHD in patients less than 64 years the duration of NIDDM had no influence on the macro-vascular complications as demonstrated in previous studies. The age however always had a significant influence on all three vascular regions examined. Albuminuria correlated as such with a number of risk factors showed a significant correlation with the incidence of pAVD and occurred more often in males with carotid artery stenoses. Other correlations established were: Hypercholesterolemia and FVIII ass. Ag respectively, and the incidence of carotid artery stenoses; blood pressure, F VIII ass. Ag and pAVD. In the female a negative correlation could be seen between the pAVD and the HDL-level. In patients with CHD sex specific correlations could be determined to blood pressure, HbA1c, c-peptide and triglyceride levels.

Adult↗
PubMed1989

Selective loss of HLA-A or HLA-B antigen expression in colon carcinoma.

A panel of colorectal carcinomas has been examined immunohistologically with mAb specific for allodeterminants of HLA-A or HLA-B, and with mAb reactive with HLA-A,B,C framework determinants or beta 2-microglobulin. Out of 85 carcinomas, 5 cases were completely negative for all class I Ag in the tumor cell population. Fifteen cases exhibited a differential expression of HLA-A and HLA-B products in all tumor cells or in a subset. Such tumor cells showed strong staining with monomorphic HLA antibodies but failed to stain with certain allospecific mAb. Negativity of tumor cells was scored only when normal stromal cells within the tumor mass were clearly labeled, indicating expression of the particular allodeterminant(s) in the given tissue. Four carcinomas showed a selective loss of HLA-A2 or a non-A2 HLA-A allospecificity in all tumor cells or a major subset, whereas HLA-B Ag were expressed. Seven cases showed a selective loss of the HLA-Bw6 superspecificity in the tumor cell population; HLA-Bw4 and HLA-A Ag were present. Three cases exhibited a combined loss of HLA-A2 and HLA-Bw6 Ag, with non-A2 HLA-A and HLA-Bw4 Ag being expressed. A further case was HLA-Bw6/Bw4 negative in a major tumor cell subset and HLA-A negative in the complementary minor subset. The results show that a considerable proportion of colorectal carcinomas is heterogeneous with regard to HLA-A and HLA-B expression. The reasons for the appearance of tumor subsets with complete loss of class I Ag or selective loss of only HLA-A or HLA-B Ag are not clear, but it is conceivable that some of them arose because they have escaped immunoselection.

Alleles↗
PubMed1989

A physical map including a new class I gene (cda12) of the human major histocompatibility complex (A2/B13 haplotype) derived from a monosomy 6 mutant cell line.

To avoid interpretative problems due to restriction fragment length polymorphisms, the monosomy 6 mutant cell line BM19.7 was employed to establish a molecular map of the human major histocompatibility (HLA) complex in the A2,B13,Bw4,DRw6,DRw52,DQw1,DPw2 haplotype. Results were obtained mainly by field-inversion gel electrophoresis and Southern blotting techniques. The map extends to 4800 kb and includes the HLA complex with a length of 4200 kb. Five HTF islands could be positioned on the map. The class I region has a size of about 2000 kb and includes nonclassical HLA class I genes, some of which must be localized within 200 kb telomeric of HLA-A. A new class I gene, cda12, distinct from HLA-A, HLA-B, or HLA-C, has been localized within 50 kb from HLA-A. The class I region contains a gap of about 500 kb, just telomeric of HLA-C, in which further class I genes could not be detected. The class II region has a size of 1000 kb, which is separated from the class I region by about 1200 kb. The 5' end of the HLA-B gene is situated centromeric, giving an orientation opposite to that of the TNFA and TNFB loci. The estimated length of the HLA complex correlates well with its size determined cytogenetically using mutant cell lines with interstitial deletions.

Cell Line↗
PubMed1988

Lack of HLA class I and class II antigens on human preimplantation embryos.

The expression of HLA Ag on polyploid early human embryonic stages, obtained in an in vitro fertilization and embryo transfer program, was investigated by indirect immunofluorescence tests using a panel of mAb. Neither HLA class I Ag, beta 2-microglobulin, nor HLA class II molecules could be detected on blastomers. The zona pellucida also lacked these Ag, but granulosa cells expressed HLA class I Ag, beta 2-microglobulin, and HLA class II Ag. These results make it likely that the absence of HLA Ag is one of the mechanisms involved in protecting the implanting embryo from rejection by the immunocompetent mother.

Antibodies, Monoclonal↗