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H Hauser

Publications and source records attributed to H Hauser.

At least 127 records · Page 7Linked to original sources
PubMed1993

Dicistronic transcription units for gene expression in mammalian cells.

Dicistronic vectors utilizing the internal ribosomal entry site sequence of poliovirus as the intercistronic region were constructed for gene expression in mammalian cells. We have developed two monocistronic expression vectors which facilitate the creation of dicistronic expression plasmids. The dicistronic expression plasmids encode transcription units which allow the coordinated translation of the two genes. Using internal luciferase and secreted alkaline phosphatase, we show the correlated expression of both reporter genes and expression levels comparable to those achieved by the respective monocistronic expression vectors.

Alkaline Phosphatase↗
PubMed1993

Interferon regulatory factor 1 (IRF-1) mediates cell growth inhibition by transactivation of downstream target genes.

Interferon regulatory factor 1 (IRF-1) is a DNA-binding factor which recognizes regulatory elements in the promoters of interferon (IFN)-beta and some IFN-inducible genes. We observed that expression of transfected murine IRF-1 in different mammalian cell lines leads to down-regulation or stop of proliferation depending on the extent of expression. Expression of fusion proteins composed of IRF-1 and the hormone binding domain of the human estrogen receptor does not exhibit IRF-1 activity in the absence of estrogen. However, after estrogen treatment of the cells IFN-beta promoters are activated and the cells stop growing. As shown by expression of IRF-1 mutants both functions of the IRF-1-protein require DNA-binding and transcriptional activation. Since secreted factors including IFNs are not responsible for the anti-proliferative effect of IRF-1 we suggest that IRF-1 may be regarded as a negative regulator of cell growth which acts by activation of down-stream effector genes.

Animals↗
PubMed1993

The effect of positive and negative pH-gradients on the stability of small unilamellar vesicles of negatively charged phospholipids.

The stability of small unilamellar vesicles (SUV) made from negatively-charged phosphatidate by ultrasonication or pH-jump has been investigated. As criteria for the vesicle stability are used: (I) the bilayer integrity as judged from the permeability of the fluorescent probe carboxyfluorescein (CF) and (II) the susceptibility of the phospholipid vesicles to fusion as judged by gel filtration and freeze-fracture electron microscopy. Egg phosphatidate SUV (PA-SUV) whose internal cavity is in equilibrium with the dispersion medium are strictly speaking thermodynamically unstable by these criteria. They may, however, be regarded as stable from a practical point of view. CF-release is observed with a half-time of 14 days and also some vesicle fusion, particularly at low temperature (4 degrees C). The small effects observed, e.g., the small tendency of the vesicles to undergo fusion is probably due to the high surface charge density of PA bilayers. A main finding of this work is that the same positive pH-gradient which is used in the pH-jump method to drive the formation of SUV from large phosphatidic acid bilayer sheets has a stabilizing effect on the resulting PA-SUV. Stabilization is achieved by positive pH-gradients of about two pH-units or more with the pH of the external medium exceeding the pH of the vesicle cavity. Under these conditions, up to about 8 weeks no significant loss of entrapped CF and no fusion of SUV was observed both at 4 degrees C and room temperature. In contrast, a reverse or negative pH-gradient of several pH units applied to PA-SUV (with the external pH being lower than that of the vesicle cavity) destabilizes PA-SUV. Such a gradient can be shown to lead to a dramatic perturbation of the lipid bilayer packing as evident from a significant increase in CF permeability. The local perturbation of the phospholipid bilayer is accompanied by massive vesicle fusion which is prominent at low temperature (4 degrees C).

Drug Stability↗
PubMed1993

Computed tomography and fine-needle aspiration cytology for preoperative evaluation of cystic tumours of the pancreas.

Cystic neoplasms of the pancreas are rare. They may present as a mucinous (malignant or potentially malignant) tumour or as benign serous cystadenoma. Accurate preoperative diagnosis is therefore essential, as an asymptomatic serous tumour may safely be followed clinically for years, whereas mucinous tumours require aggressive surgery. Thirteen patients with cystadenoma and cystadenocarcinoma of the pancreas were reviewed and how best to improve the rate of preoperative diagnosis was considered. Fine-needle aspiration cytology and computed tomography enable accurate preoperative distinction between mucinous and serous cystic tumours of the pancreas.

Adult↗
PubMed1993

Interferon-beta promoters contain a DNA element that acts as a position-independent silencer on the NF-kappa B site.

The human interferon-beta (IFN-beta) promoter contains several functional domains that contribute to its virus-inducible regulation. One of them, PRDII, and NF-kappa B-binding sequence, can function as a constitutively activating element. Due to the presence of a negative regulatory domain that mediates a constitutive repression the natural IFN-beta promoter is silent in the non-induced state. Within this domain we have delimited an 11 bp element that acts as a negative regulatory element (NRE) of PRDII. Although the NRE is physically overlapping with PRDII in the IFN-beta promoter, it acts as a position-independent silencer of PRDII. Virus infection, which leads to the transcriptional activation of the IFN-beta promoter, does not alter the negative activity of the NRE on an isolated PRDII. It is the cooperative effect of PRDI and PRDII that is able to overcome the NRE function after virus infection. By UV cross-linking analysis using uninduced and virus-induced nuclear extracts, we show that two factors with molecular masses of approximately 95 and 100 kDa bind to the NRE.

Base Sequence↗
PubMed1993

Mycoplasma detection by PCR analysis.

The polymerase chain reaction (PCR) method was used to detect mycoplasma contamination in a panel of 42 continuous cell lines. According to the microbiological cultivation assay on agar, 29 cell lines were chronically infected and 13 cell lines were negative. Sets of outer and inner primers (nested double-step PCR) were applied which anneal to DNA sequences coding for conserved regions of the 16S rRNA. These oligonucleotides allow for the amplification of DNA regions found in at least 25 mycoplasma species (including the ones most commonly found in cell cultures), but do not cross-hybridize with DNA from eukaryotic cells. Mycoplasma-positive cell lines showed distinctive bands in ethidium bromide-stained gels, both after the first round of amplification as well as after the second PCR; all agar-negative cell lines were also unambiguously negative in the PCR assay. Thus, neither false-positive nor false-negative results occurred. Provided that the proper PCR working conditions are scrupulously observed, the PCR amplification has several outstanding advantages: high sensitivity, specificity, reliability, objectivity, speed, and simplicity.

Animals↗
PubMed1993

A heptanucleotide sequence mediates ribosomal frameshifting in mammalian cells.

Ribosomal frameshifting is an essential requirement for replication of many viruses and retrovirus-like elements. It is regarded as a potential target for antiretroviral therapy. It has been shown that the frameshifting event takes place in the -1 direction within a sequence, the slippery sequence, which is usually followed by structured RNA. To distinguish between the basic sequence requirements and the modulating elements in intact cells, we have established a sensitive assay system for quantitative determination of ribosomal frameshifting in mammalian cell culture. In this assay system, the gag and pol genes of human immunodeficiency virus type 1 are replaced by the genes for the functional enzymes beta-galactosidase and luciferase, respectively. The sensitivity of the test system allows us to demonstrate for the first time that the slippery sequence, a heptanucleotide, is sufficient to mediate a basal level of ribosomal frameshifting independent of its position within a gene. The stem-loop sequence serves only as a positive modulator. These data indicate that frameshifting could also occur during translation of cellular genes in which a slippery sequence is present within the reading frame. The resulting putative transframe proteins might have a functional importance for cellular processes.

Animals↗
PubMed1993

Malignant fibrous histiocytoma of the mesentery--a rare cause of abdominal pain. Case report with a review of literature.

Malignant fibrous histiocytoma (MFH) is a tumor most frequently occurring in lower and upper extremities and in retroperitoneum. This paper presents the extremely rare case of a 55-year-old male patient with a MFH of storiform pleomorphic subtype originating from the mesentery. Sonography, computed tomography as well as endoscopy and ERCP did not reveal the diagnosis. Finally the tumor was diagnosed by laparoscopy with biopsy and histological examination. Two months after diagnosis of the tumor the patient died of bronchopneumony and heart failure contracted during a generalisation of MFH.

Abdominal Pain↗
PubMed1992

Human-immunodeficiency-virus-type-1-encoded Vpu protein is phosphorylated by casein kinase II.

Vpu as a human-immunodeficiency-virus-type-1-encoded 81-amino-acid integral-membrane protein was expressed in Escherichia coli using the inducible ptrc promoter of an ATG fusion vector. Recombinant Vpu is associated with membranes of E. coli and could be partially solubilized by detergents. Recombinant Vpu was phosphorylated in vitro with purified porcine casein kinase II (CKII) as well as with a CKII-related protein kinase found in cytoplasmic extracts of human and hamster cells. Recombinant Vpu associated with E. coli membranes has turned out to be the best substrate for in vitro phosphorylation with CKII. This reaction can be inhibited by heparin and the ATP analogue 5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole (DRB), both known to be potent inhibitors of CKII. Radiolabelled gamma ATP and gamma GTP were used as phosphate donors in vitro phosphorylation of recombinant Vpu. In vivo phosphorylation of Vpu in HIV-1-infected H9 cells was also inhibited by DRB. We concluded therefrom that the Vpu protein is phosphorylated by the ubiquitous CKII in HIV-1-infected human host cells. Two seryl residues in the sequence of Vpu (position 52 and 56) correspond to the consensus S/TXXD/E for CKII. These potential phosphorylation sites are located within a well-conserved dodecapeptide of Vpu (residues 47-58), which is found in different HIV-1 strains as well as in a Vpu-like protein of SIVCPZ. Monoclonal and polyclonal antibodies directed against two different epitopes of Vpu were used for immunoprecipitation of Vpu from HIV-1-infected cells and for detection of Vpu in Western blot analyses. Vpu from HIV-1-infected cells as well as recombinant Vpu expressed in E. coli were determined by SDS/PAGE using 6 M urea to be 9 kDa, which corresponds to the calculated molecular mass of Vpu.

Adenosine Triphosphate↗
PubMed1992

A bifunctional HBED-derivative for labeling of antibodies with 67Ga, 111In and 59Fe. Comparative biodistribution with 111In-DPTA and 131I-labeled antibodies in mice bearing antibody internalizing and non-internalizing tumors.

To investigate whether bifunctional ligands containing chelating structures other than EDTA and DTPA and metallic radiotracers other than 111In will reduce the non-specific radioactivity uptake in the liver during immunoscintigraphy, we synthetized an isothiocyanato-substituted phenolic polyaminocarboxylic acid (HBED-CI) for labeling of MAbs with 67Ga, 111In and 59Fe. Biodistribution of HBED-CI-labeled MAbs was compared to that of 131I and 111In-DTPA labeled MAbs in nude mice bearing tumors, which differ with regard to intracellular internalization and catabolism of the corresponding MAb-antigen complex. In the liver a continuous radioactivity excretion for 67Ga-HBED-CI-labeled MAbs was observed with kinetics that parallel 131I clearance after administration of 131I-MAbs, while 111In-HBED-CI-labeling led to a constant 111In liver level quite similar to that of 111In-DTPA-MAbs. In tumors, 67Ga-HBED-CI-MAb uptake again paralleled that of 131I-MAbs, showing continuous accumulation in tumor tissues when internalization of the MAb-antigen complex was not involved. A much lower uptake, which peaked between 24 and 48 h, was found in the case of MAb-antigen internalization. 111In of 111In-HBED-CI- and 111In-DTPA-labeled MAbs continuously accumulated in both types of tumors. Compared with 111In-DTPA-MAbs, an improvement in tumor-to-liver ratios, due to the reduced liver radioactivity associated with 67Ga-HBED-CI-labeled MAbs, could only be obtained with non-internalizing tumors. The time course of radioactivity distribution in the liver and in MAb-internalizing tumors after administration of 67Ga-HBED-CI-, 111In-HBED-CI- and 111In-DTPA-labeled MAbs further indicates a dominating influence of the metallic radiotracer rather than the ligand on retention or excretion of radioactivity in MAb-catabolizing tissues.

Animals↗
PubMed1992

Role of imaging technics in the classification of acute pancreatitis.

This paper is a review of some aspects of acute pancreatitis (AP) (definition criteria, outcome, and prognostic factors) and a reminder of the invaluable contribution of computed tomography (CT) in confirming the diagnosis of AP, distinguishing between edematous and necrotizing forms, and in providing prognostic information via detection of possible extrapancreatic spreads (EPS). The Geneva experience (510 cases of AP over a 9-year period) has shown that no fatalities occurred when no EPS were found on CT performed within 48 h of admission; mortality was 1.5% in the case of 1 or 2 EPS and 19% in the case of 3 EPS or more.

Acute Disease↗
PubMed1992

[Breast cancer in the catchment area of the Graz Institute of Pathology. Evaluation of morphologic parameters based on 1,510 cases].

The patient's age, tumour size, histological type and degree of differentiation as well as involvement of axillary lymph nodes are decisive for prognosis and therapy of breast cancer. Moreover these parameters reflect the achievement of early diagnosis and the surgical standard of treatment of breast carcinomas. Therefore we retrospectively reviewed 1510 cases diagnosed from 1984-1987. Non-invasive carcinomas were diagnosed in 4%. 75% of them were classified as intraductal carcinoma and 25% as lobular carcinoma in situ. 96% of the tumours were invasive at time of diagnosis. Invasive ductal carcinoma (NOS-type) was found in 70.2%, invasive lobular carcinoma in 12.3%. 3.2% of the tumours showed both ductal and lobular differentiation and 2.3% corresponded to invasive ductal carcinoma with a predominantly intraductal component. Medullary and mucinous carcinomas were detected in 2.1% and 2% of cases, respectively. Papillary carcinomas were observed in 0.9%, the frequency of other histological types was less than 1%. 44% of the tumours corresponded to UICC-category pT1, 38% to pT2, 6% to pT3 and 8% to pT4. A meaningful correlation of tumour size and axillary lymph node involvement was possible in only 906 cases, in which 10 or more lymph nodes were verified histologically. Lymph node metastases were detected in 23% of tumour category pT1 and in 47% of category pT2. PT3- and pT4-tumours metastasized to axillary lymph nodes in 77 and 86% of cases, respectively.

Adult↗
PubMed1992

[Acute pancreatitis: radiologic evaluation].

In the acute pancreatitis computerized tomography (CT) is within all radiological technics the method with the highest diagnostic rate. CT allows a detailed analysis of the extent and nature of lesions related to acute pancreatitis, and that from the thorax to the pelvis. It is possible to grade the severity of pancreatitis on the base of its morphological changes within the gland itself and in the extraglandular spread. The differentiation between edema and necrosis is discussed as well as their evolution and the complications appearing during this disease. Percutaneous diagnostic and therapeutic procedures under CT guidance are quite helpful. The prognostic value of CT in the early stage of acute pancreatitis is demonstrated with a clinical-radiological study including 202 patients.

Acute Disease↗
PubMed1991

Lipid asymmetry in rabbit small intestinal brush border membrane as probed by an intrinsic phospholipid exchange protein.

All classes of phospholipids present in brush border membrane are exchanged in a 1:1 ratio for egg phosphatidylcholine when brush border membrane vesicles from rabbit small intestine are incubated with small unilamellar vesicles of egg phosphatidylcholine. The exchange reaction exhibits biphasic kinetics similar to those of the hydrolysis of brush border membrane phospholipids by phospholipase A2 and sphingomyelinase C. In both reactions there is an initial fast phase followed by a markedly slower one. The phospholipid exchange appears to be catalyzed by intrinsic brush border membrane protein(s), while the digestion by phospholipases is mediated by externally added enzymes. From a comparison of the kinetics of phospholipid exchange and phospholipid hydrolysis, the following conclusions can be drawn: Both sets of experiments indicate the presence of two phospholipid pools differing in the rate of phospholipid exchange and hydrolysis. Except for sphingomyelin, the size of the two phospholipid pools derived from phospholipid exchange is in good agreement with that derived from phospholipid hydrolysis. This is the main finding of this work, and on the basis of this result the two lipid pools are tentatively assigned to phospholipid molecules located on the outer and inner layer of the brush border membrane. The slow rate of phospholipid exchange reflects the rate of transverse or flip-flop movement of phospholipids. The half-time of this motion is approximately 8 h for isoelectric (neutral) phospholipids such as phosphatidylethanolamine and approximately 80 h for negatively charged phosphatidylserine and phosphatidylinositol. Isoelectric phospholipids (phosphatidylcholine, phosphatidylethanolamine) are preferentially located on the inner (cytoplasmic) side (to about 70%) while the negatively charged phospholipids are more evenly distributed: 55-60% are located on the inner side.

Animals↗
PubMed1991

The effect of monoacylglycerol on the phase behavior of egg phosphatidylcholine.

Phosphatidylcholine bilayers can accommodate large quantities of monoacylglycerol. Incorporating up to 40% monoacylglycerol has little effect on the orientation and motion of the phosphatidylcholine polar group. Briefly heating mixed dispersions of 1-monooleoylglycerol/egg phosphatidylcholine (1:1, weight ratio; 2.1:1, mole ratio) to 50-60 degrees C induced spontaneous vesiculation: unilamellar and some oligolamellar vesicles bud off the large multilamellar particles. The size of the resulting vesicles ranges from 100 to 1000 nm, with the bulk of the vesicles having diameters between 100 and 500 nm. The spontaneous vesiculation process is reflected in the visual clearance of the mixed lipid dispersion and in the collapse of the 31P powder NMR spectrum to a sharp, asymmetric peak. The narrowing of the 31P-NMR spectrum is explained in terms of additional molecular and/or segmental motion of the lipid polar groups. In mixed dispersions of 1-monooleoylglycerol/egg phosphatidylcholine containing an excess of 1-monooleoylglycerol (greater than or equal to 50%) domain formation takes place, i.e., the formation of local clusters enriched in either of the two lipids. As a result the mechanical properties of these mixed lipid bilayers seem to be quite different from those of pure egg phosphatidylcholine.

Chromatography, Gel↗
PubMed1991

Membrane proteins exposed on the external side of the intestinal brush-border membrane have fusogenic properties.

The intestinal brush-border membrane contains one or several membrane proteins that mediate fusion and/or aggregation of small unilamellar egg phosphatidylcholine vesicles. The fusion is accompanied by a partial loss of vesicle contents. Proteolytic treatment of the brush-border membrane with proteinase K abolishes the fusogenic property. This finding suggests that the fusogenic activity is associated with a membrane protein exposed on the external or luminal side of the brush-border membrane. Activation of intrinsic proteinases of the brush-border membrane liberates water-soluble proteins (supernate proteins). These proteins behave in an analogous way to intact brush-border membrane vesicles; they induce fusion of egg phosphatidylcholine vesicles and render the egg phosphatidylcholine bilayer permeable to ions and small molecules (Mr less than or equal to 5000). Furthermore, supernate proteins mediate phosphatidylcholine and cholesterol exchange between two populations of small, unilamellar phospholipid vesicles. Supernate proteins are fractionated on Sephadex G-75 SF yielding three protein peaks of apparent Mr greater than or equal to 70,000, Mr = 22,000 and Mr = 11,500. All three protein fractions show similar phosphatidylcholine-exchange activity, but they differ in their effects on the stability of egg phosphatidylcholine vesicles. The protein fraction with an apparent Mr greater than or equal to 70,000 has the highest fusogenic activity while the protein fraction of apparent Mr = 11,500 appears to be most effective in rendering the egg phosphatidylcholine bilayer permeable.

Animals↗