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Biomedical subjects

J Meier

Publications and source records attributed to J Meier.

At least 73 records · Page 4Linked to original sources
PubMed1994

Type B lamins remain associated with the integral nuclear envelope protein p58 during mitosis: implications for nuclear reassembly.

p58 (also referred to as the lamin B receptor) is an integral membrane protein of the nuclear envelope known to form a multimeric complex with the lamins and other nuclear proteins during interphase. To examine the fate of this complex during mitosis, we have investigated the partitioning and the molecular interactions of p58 in dividing chicken hepatoma (DU249) cells. Using confocal microscopy and double immunolabelling, we show here that lamins B1 and B2 co-localize with p58 during all phases of mitosis and co-assemble around reforming nuclei. A close juxtaposition of p58/lamin B-containing vesicles and chromosomes is already detectable in metaphase; however, p58 and lamin reassembly proceeds slowly and is completed in late telophase--G1. Flotation of mitotic membranes in sucrose density gradients and analysis of mitotic vesicles by immunoelectron microscopy confirms that p58 and most of the type B lamins reside in the same compartment. Co-immunoprecipitation of both proteins by affinity-purified anti-p58 antibodies shows that they are physically associated in the context of a mitotic p58 'sub-complex'. This sub-assembly does not include the type A lamins which are fully solubilized during mitosis. Our data provide direct, in vivo and in vitro evidence that the majority of type B lamins remain connected to nuclear membrane 'receptors' during mitosis. The implications of these findings in nuclear envelope reassembly are discussed below.

Animals↗
PubMed1994

Studies on venom and venom apparatus of Fea's viper, Azemiops feae.

Enzyme activities tested in the venom gland extract of Azemiops feae snake are similar to those of viperine venoms, except that Azemiops venom has no blood clotting, haemorrhagic or myolytic activities. The venom gland exhibits the characteristic feature of a viperine gland, but the fangs possess a ridge at the tip laterally to the venom orifice and a blade-like structure on the back seen only in some opisthoglyphous and Atractaspidae snakes.

Amino Acid Oxidoreductases↗
PubMed1994

Lamins and lamin-associated proteins.

A variety of morphological and biochemical studies have established that the nuclear lamins play an important role in nuclear structure and dynamics. Recent work reveals the existence of specialized lamin isotypes and novel pathways of modulation of lamin import into the nucleus via phosphorylation by protein kinase C. Other studies also unveil a wide spectrum of molecular interactions between the lamin proteins and integral membrane components of the nuclear envelope.

Animals↗
PubMed1994

[Combined use of laparoscopic cholecystectomy and endoscopic retrograde cholangiography (ERC) and papillotomy (ERCP) in management of cholecysto-choledocholithiasis].

In a review of 328 cases the combination of laparoscopic cholecystectomy with specific use of endoscopic retrograde cholangiography (pre- and postoperatively) proved to be a riskless, secure and time-saving procedure. In our opinion this is a minimal invasive method of treatment for patients with cholecysto-/choledocholithiasis.

Adult↗
PubMed1993

NIH conference. Epstein-Barr virus infections: biology, pathogenesis, and management.

Epstein-Barr virus (EBV) encodes genes that ensure its persistence in human B lymphocytes. Some of the genes encourage B-cell proliferation; others are poised to evade or defeat immune recognition. Immune restraints on the virus, however, are typically so effective that most infections are never symptomatic. In contrast, acute infectious mononucleosis, a self-limited lymphoproliferative illness, is common in adolescents and young adults. Unbridled proliferative illnesses arise when cellular immunity is grossly defective. Treatment of EBV-associated syndromes is largely supportive. Antiviral drugs have no proven role except in patients with oral hairy leukoplakia. Vaccine development is technically feasible but is not considered a high priority for developed nations.

B-Lymphocytes↗
PubMed1993

Upper gastrointestinal hemorrhage preceding development of Bouveret's syndrome.

Gastric outlet obstruction by a gallstone is a very uncommon clinical entity; it was first reported by Bouveret in 1896. In the patient presented, we were able to show the development of formation of the bilioenteric fistula with massive arterial bleeding from the eroded cystic artery until duodenal occlusion. The process was endoscopically and radiologically observed and documented. Although the diagnosis was made immediately, the patient had to undergo surgery because the gallstone proved to be too large to be extracted endoscopically.

Aged↗
PubMed1992

Purification and characterization of an antithrombin III inactivating enzyme from the venom of the African night adder (Causus rhombeatus).

A serine proteinase was isolated from the venom of the night adder (Causus rhombeatus) by fast protein liquid chromatography (anion-exchange, gel filtration and hydrophobic interaction). The protein (termed CR-serpinase) had an estimated mol. wt of 45,500 as determined by SDS-PAGE, pI of 4.7 and a carbohydrate content of 18.9%. Incubation of CR-serpinase with purified human antithrombin III at a molar ratio of 1:66 resulted in a loss of more than 90% of the initial AT III activity within 10 min. The reaction was dependent on heparin. In SDS-PAGE inactivation of human antithrombin III was correlated with the occurrence of two cleavage products. The cleavage site in the antithrombin III molecule was determined to be Arg 393-Ser 394 by amino-terminal sequencing. CR-Serpinase had no thrombin-like activity since no fibrinogen conversion was induced and had no procoagulant activity. CR-Serpinase activity was not inhibited by antithrombin III-heparin and was not decreased by a 10-min preincubation in normal human plasma. Inactivation of antithrombin III by CR-serpinase appeared to be very specific.

Amino Acid Sequence↗
PubMed1991

Inhibition of the protein C activator Protac, a serine proteinase from the venom of the southern copperhead snake Agkistrodon contortrix contortrix.

ProtacR, the single chain glycoprotein in the venom of Agkistrodon contortrix snake subspecies and related pit vipers has found broad application as a protein C activator in blood coagulation research and diagnosis. Inhibition studies were performed to further elucidate the nature of this serine proteinase. Benzamidine derivatives are poor inhibitors of ProtacR. Only a few 4-amidinoanilides of N alpha-substituted omega-phenyl-alpha-aminoalkylcarboxylic acids exert potent inhibitory activities. The active site of ProtacR appears to be accessible only for inhibitors with well-fitting structural features.

Anilides↗
PubMed1991

Mycoplasma phocarhinis sp. nov. and Mycoplasma phocacerebrale sp. nov., two new species from harbor seals (Phoca vitulina L.).

A total of 120 mycoplasma strains were recovered from 97 of 265 diseased seals investigated during the seal epidemic in the North Sea and in the Baltic Sea in 1988. Mycoplasmas were isolated from the respiratory tracts (including lungs), hearts, brains, and eyes of the seals. Thirty strains were filter cloned and investigated for their morphological, biochemical, and serological characteristics compared with the characteristics of previously described species. The results of an indirect immunofluorescence test, a growth inhibition test, and an immunobinding assay showed that these strains belong to two new species, for which the names Mycoplasma phocarhinis and Mycoplasma phocacerebrale are proposed. M. phocarhinis (17 strains) did not ferment glucose or hydrolyze arginine but did reduce tetrazolium chloride and potassium tellurite and produced films and spots. M. phocacerebrale (13 strains) metabolized arginine but not glucose and produced phosphatase but did not reduce tetrazolium chloride and potassium tellurite. Both species lysed sheep erythrocytes but did not absorb sheep or guinea pig erythrocytes. The type strain of M. phocarhinis is strain 852 (= ATCC 49639), and the type strain of M. phocacerebrale is strain 1049 (= ATCC 49640).

Animals↗
PubMed1991

The role of lamin LIII in nuclear assembly and DNA replication, in cell-free extracts of Xenopus eggs.

Xenopus egg extracts, which support nuclear assembly and DNA replication, were functionally depleted of lamin LIII by inoculating them with monoclonal anti-lamin antibodies. Phase-contrast microscopy and electron-microscopy studies indicated that lamin-depleted extracts supported efficient chromatin decondensation, and assembly of double membrane structures and nuclear pores on demembranated sperm heads. Immunofluorescence microscopy suggests that lamin-antibody complexes are transported across the nuclear membrane but do not assemble into a lamina. These findings were confirmed by immunoblotting analysis of isolated nuclei. Metabolic labelling studies with either biotin-11-dUTP or [32P]dCTP, revealed that nuclei lacking a lamina were unable to initiate DNA replication and that, although such nuclei could import proteins required for DNA replication (e.g. PCNA), these proteins were apparently not organized into replicon clusters.

Animals↗
PubMed1991

Effects of snake venoms on hemostasis.

Proteins found in venoms, especially of the Viperidae snake family, exert, often with a narrow specificity, activating, inactivating, or other converting effects on different components of the hemostatic and fibrinolytic systems, respectively. Some purified snake venom proteins have become valuable tools in basic research and in diagnostic procedures in hemostaseology. "Procoagulant" as well as "anticoagulant" venom components have been identified in in vitro test systems. "Procoagulant" snake venom components may cause in vivo, upon massive application as in the case of snake-bite of small prey animals, intravascular coagulation leading to circulatory arrest and rapid death. Smaller doses of procoagulant venom components applied to large organisms as in the case of snake-bite accidents in humans, may cause a consumption coagulopathy with localized or generalized bleeding. Highly purified, specific fibrinogen coagulant venom proteinases are used in human medicine to produce therapeutic defibrinogenation. These practically nontoxic venom enzymes may act synergistically with other components aggravating their toxic effects.

Animals↗
PubMed1991

Piezoelectric shock wave lithotripsy of salivary gland stones: an in vitro feasibility study.

The feasibility of fragmentation of salivary stones by a new extracorporeal piezoelectric lithotripter was investigated. A total of 40 salivary stones were submitted to piezoelectric shock wave treatment. The diameter, weight, and volume of all the stones were determined prior to shock wave administration. After shock wave administration the chemical composition of the stones was investigated by X-ray diffractometry. Fragmentation was achieved in 35 out of the 40 (87.5%) stones. Twenty-five of the 40 (62.5%) stones were disintegrated "therapeutically adequate" (residual fragments less than 1.5 mm). A statistically significant correlation was not observed between the number of discharges required for disintegration and the diameter, weight, volume, or the chemical composition of the stones.

Feasibility Studies↗
PubMed1990

Quantitative effects of allogeneic small-bowel transplantation on nutrient digestion and on body protein balance as determined in vivo in rats.

Heterotopic and orthotopic small-bowel allotransplantation was carried out in Wistar rats using grafts reduced to one-half of the original length. Portocaval venous anastomoses and intestinal end-to-end anastomoses were performed. Animals either with complete or with partially reduced native small-bowel served as control. In a total of 51 rats, 88 quantitative in vivo measurements of apparent digestion and absorption of dietary dry matter, organic matter, energy, protein, fat, total ash, and glucose were carried out. Body protein retention was calculated from intake and losses with feces and urine. The digestion trials comprised 8 days of adaptation and 10 days of continual recording of nutrient balance data. In experiments 1 and 2, digestibility coefficients were obtained before and after transplantation within the same animals, untreated or initially treated with cyclosporine A after surgery. Similar groups of rats untreated, with partial resection and with transplantation of the small-bowel, followed by temporary cyclosporine treatment, were used in experiment 3. In experiment 4, rats with transplanted intestines from experiments 1 and 2 were subjected to a further digestion trial 4 to 6 months after the respective first trial. With transplantation of the small intestine, apparent digestion and absorption of nutrients, as well as protein retention, tended to be lower. Significant depression occurred in the digestion of fat and ash. In long-term survivors all parameters decreased further. The adverse effects on fat and ash digestion seemed to be pronounced when rejection occurred. Fecal fat excretion might therefore be an indication of dysfunction of small-bowel grafts. Digestion was less imparied if cyclosporine was applied, and part of the effects on digestion and protein balance could be attributed to the shortened bowel.

Animals↗
PubMed1990

Antigenic relationship between the venom of the night adder Causus maculatus and venoms of other viperids.

Monovalent antivenoms were raised in mice against the venoms of Causus maculatus, Vipera ammodytes, Echis carinatus, Cerastes cerastes, Bitis arietans, Agkistrodon rhodostoma and Bothrops atrox. These antivenoms as well as four commercially available antivenoms were tested against the venoms of 15 viperid species by means of immunoelectrophoresis and/or ELISA. Cross-reactive protein bands were determined by immunoblot. ELISA cross-reactions of C. maculatus antivenom were low with all heterologous venoms. When investigating the other viperine antivenoms in ELISA stronger cross-reactions were observed with several heterologous venoms. In immunoblot, two heterologous antivenoms cross-reacted with one or two protein bands of C. maculatus venom whereas there were at least four heterologous antivenoms cross-reacting with each of the other venoms. The findings indicate that there is little antigenic affinity between C. maculatus venom and the other venoms investigated. Broad in vitro cross-reactions between viperine antivenoms and Causus venom which were reported in literature seem to be attributable to the use of antivenoms of commercial grade. Specificity of commercially produced, mono- or polyvalent antivenoms may not be strictly limited to those venoms, against which potency is claimed on the label of the product.

Animals↗
PubMed1990

Epitope-sharing between Mycoplasma arthritidis and chondrocytes demonstrated by monoclonal antibodies.

Polyclonal and monoclonal antibodies against Mycoplasma (M.) arthritidis membranes were investigated in the indirect immunofluorescence test (IIFT) and enzyme immunoassay (EIA) for their reactivity with rat and human chondrocytes as well as with rat skin fibroblasts. The monoclonal antibody A 79 gave positive reactions with rat chondrocytes in the IIFT up to a dilution off 1: 128 and in EIA up to a dilution of 1:16. In the EIA, the monoclonal antibodies A 31, A 32 and A 58 recognized M. arthritidis as well as rat and human chondrocyte membrane antigens up to dilutions of 1:128 and 1:256 and rat skin fibroblasts up to dilutions of 1:32/64. In the IIFT, the whole surfaces of the rat and human chondrocytes were strongly fluorescing after the treatment with the polyclonal antiserum against M. arthritidis. The monoclonal antibody A 79 caused weak fluorescence (rat chondrocytes) or no fluorescence (human chondrocytes) on the surface of the chondrocytes but a stronger fluorescence on areas around and between them. From these results it can be concluded that A 79 probably reacts with antigens of the chondrocyte matrix.

Animals↗