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H Hauser

Publications and source records attributed to H Hauser.

At least 181 records · Page 10Linked to original sources
PubMed1988

Posttranslational modification of interleukin-2 is a late event during activation of human T lymphocytes by ionophore A23187 and phorbol ester.

Human peripheral blood lymphocytes secrete high titers of interleukin-2 (IL-2) after stimulation by Ca2+-ionophore A23187/phorbol 12-myristate-13-acetate. During the first 30 hours of incubation cells secrete only the nonglycosylated IL-2 M form of the lymphokine, the glycosylated forms IL-2 N1,2 being detected only after prolonged culture times (30-48 h). After recultivation of cells for a second 48 h period (without additional mitogen), the glycosylated and nonglycosylated IL-2 forms are secreted at a constant ratio of 7:3 throughout. The detection of glycosylated IL-2 is parallelled by an increase in cellular glycosyltransferase activities involved in formation of sialylated oligosaccharides O-linked to proteins.

Calcimycin↗
PubMed1988

Human lysosomal acid phosphatase is transported as a transmembrane protein to lysosomes in transfected baby hamster kidney cells.

BHK cells transfected with human lysosomal acid phosphatase (LAP) cDNA (CT29) expressed 70-fold higher enzyme activities of acid phosphatase than non-transfected BHK cells. The CT29-LAP was synthesized in BHK cells as a heterogeneously glycosylated precursor that was tightly membrane associated. Transfer to the trans-Golgi was associated with a small increase in size (approximately 7 kd) and partial processing of the oligosaccharides to complex type structures. CT29-LAP was transferred into lysosomes as shown by subcellular fractionation, immunofluorescence and immunoelectron microscopy. Lack of mannose-6-phosphate residues suggested that transport does not involve mannose-6-phosphate receptors. Part of the membrane-associated CT29-LAP was processed to a soluble form. The mechanism that converts CT29-LAP into a soluble form was sensitive to NH4Cl, and reduced the size of the polypeptide by 7 kd. In vitro translation of CT29-derived cRNA in the presence of microsomal membranes yielded a CT29-LAP precursor that is protected from proteinase K except for a small peptide of approximately 2 kd. In combination with the sequence data available for LAP, these observations suggest that CT29-LAP is synthesized and transported to lysosomes as a transmembrane protein. In the lysosomes, CT29-LAP is released from the membrane by proteolytic cleavage, which removes a C-terminal peptide including the transmembrane domain and the cytosolic tail of 18 amino acids.

Acid Phosphatase↗
PubMed1988

Oncogene expression in endocrine pancreatic tumors.

The mRNA expression of the (proto)oncogenes Ha-ras, Ki-ras, fos, c-myc, N-myc, and sis was studied in five pancreatic endocrine tumors and two non-neoplastic pancreatic tissues. Compared with non-tumorous pancreatic tissue, Ha-ras and Ki-ras mRNA was overexpressed up to 42-fold in all the tumors; metastasizing tumors showed 2-6 times higher Ha-ras mRNA levels than benign neoplasias. In contrast, c-myc mRNA levels were higher in normal tissue than n tumors and fos mRNA levels did not differ significantly between tumors and normal tissue. The activities of Ki-ras, fos and c-myc mRNA expression did not correlate with any of the histological or biological properties of the tumors, nor with the clinical course of disease. Our results, although based on a limited number of cases, suggest tha Ha-ras and Ki-ras mRNA overexpression is associated with the development of pancreatic endocrine tumors. The measurement of Ha-ras mRNA levels may contribute to the assessment of tumor prognosis.

Adult↗
PubMed1988

Phase behaviour of lipid X.

The phase behaviour of aqueous dispersions of lipid X, a precursor of bacterial lipopolysaccharides has been investigated by a variety of physico-chemical techniques. The results are consistent with the presence of disk-shaped micelles with an average diameter of 13 +/- 1.8 nm. The critical micellar concentration in water and physiological saline is 4 x 10(-5) M. Consistent with the formation of micelles in water and physiological saline is the finding that lipid X is in the liquid-crystalline state at temperatures higher than 0 degrees C. The packing and the dynamics of lipid X are characteristic of micelles. Close to the polar group the hydrocarbon chains are significantly more mobile and disordered than in the corresponding region of lipid bilayers. From monolayer studies an estimate of the molecular area of lipid X is derived; under physiological conditions the area/molecule is about 0.50 nm2 at 30 mN/m indicating that lipid X has a wedge-like shape. The two pK values of the primary phosphate group of lipid X are pK1 approximately 1.3 and pK2 = 8.2. At pH values less than 7, the area/molecule decreases, i.e. the packing of the lipid X molecules becomes tighter, and there is also a decrease in the solubility of lipid X. As is characteristic of charged lipids, the state of aggregation (phase behaviour) of lipid X depends on pH, the ionic strength and the nature of the counterion.

Calorimetry, Differential Scanning↗
PubMed1988

Value of contrast-enhanced computerized tomography in the early diagnosis and prognosis of acute pancreatitis. A prospective study of 202 patients.

Two hundred two patients admitted with the clinical suspicion of acute pancreatitis underwent computerized tomography scanning within 36 hours of admission. The diagnostic value of the computerized tomography findings was excellent, with a sensitivity of 92 percent and a specificity of 100 percent. One hundred seventy-six patients with acute pancreatitis defined according to the overall clinical course were included in the prognostic study. The pancreatitis was fatal in 21 patients, severe in 47 patients, and mild in 108 patients. The computerized tomography findings were classified into the following three groups on the basis of the extent of phlegmonous extrapancreatic spread: Group I, no phlegmonous extrapancreatic spread (100 patients, none died); Group II, phlegmonous extrapancreatic spread in one or two areas (28 patients, mortality rate 4 percent); and Group III, phlegmonous extrapancreatic spread in three or more areas (48 patients, mortality rate 42 percent) (p less than 0.0001). The following three scores from prognostic clinical and laboratory data were also obtained: Score 1, zero or one positive sign (82 patients, none died); Score 2, two to four positive signs (54 patients, mortality rate 13 percent); Score 3, five or more positive signs (40 patients, mortality rate 35 percent) (p less than 0.001). The combination of computerized tomography findings and prognostic signs had the best predictive value. Patients in Group III, Score 3 (24 patients) or Group III, Score 2 (19 patients) had mortality rates of 58 percent and 32 percent, respectively, and complications developed in all of the survivors. In addition, all except two acute pancreatitis patients in whom pancreatic abscess developed were found in Group III (p less than 0.0001). Furthermore, for Group III patients, the prediction of death associated with abscesses was enhanced by the number of prognostic signs. The mortality rate increased from 17 percent for Score 2 patients to 81 percent for Score 3 patients (p = 0.0078). As a result of this study, we recommend early computerized tomography for all Score 2 and Score 3 patients, since it allows prompt recognition of patients at high risk for systemic and local complications. Adequate therapy can then be directed to the group of patients to whom it is best suited. Serial computerized tomographies should be reserved for those patients presenting with phlegmonous extrapancreatic spread.

Acute Disease↗
PubMed1988

Factors influencing the in vitro stability of artificial red blood cells based on hemoglobin-containing liposomes.

The effects of membrane phospholipid composition, surface charge and cholesterol content on the deteriorating interactions between hemoglobin (Hb) and phospholipid bilayers were studied. Hb was either encapsulated in multilamellar liposomes (hemosomes), or incubated with small unilamellar vesicles (SUV). Negatively charged phospholipids increased the rate of oxyHb decay in unsaturated lipid hemosomes. This effect was not linked to Hb-induced lipid peroxidation, since the latter process was inhibited in hemosomes with negative surface charge. Cholesterol decreased both the negative-charge elicited fall in oxyHb-level, and Hb-induced lipid peroxidation. In hemosomes prepared from synthetic, saturated phospholipids, negative surface charge (phosphatidic acid) elicited drastic denaturation (bleaching) of Hb, which effect was completely prevented by cholesterol. The experiments with SUV prepared from unsaturated lipids indicated intercalation of Hb into the bilayer due to hydrophobic interaction. This process was decreased by membrane cholesterol. Negative surface charge of the vesicles, through an electrostatic interaction with the positively charged heme, resulted in the displacement of heme relative to globin. This process was also decreased by cholesterol. With saturated, negatively charged SUV, the penetration of Hb into the bilayer was smaller, but the ionic interaction between the acidic lipids and the heme led to the detachment of the letter from globin. Cholesterol in such membrane increased the intercalation of Hb into the membrane, and at the same time completely prevented the loss of heme. The latter observations suggest that the fluid phase of the membrane favours the hydrophobic interaction with the protein, whereas the gel state promotes the partition of the heme into the bilayer. It is suggested that the effects of cholesterol are indirect, mediated by changes in membrane fluidity. By highlighting potentially harmful reactions between Hb and phospholipid bilayers, our findings may help the design of in-vitro stable hemosomes.

Blood Substitutes↗
PubMed1988

Efficient expression system for human antithrombin III in baby hamster kidney cells.

A DNA fragment carrying the enhancer of an immediate early gene of human cytomegalovirus (hCMV) was tested as a transcriptional control element by fusion downstream of a transcription unit for human antithrombin III (AT III) driven by the Simian virus (SV40) enhancer and promoter. Measurement of transient AT III expression in baby hamster kidney cells (BHK) shows that by the presence of the hCMV enhancer the synthesis of AT III is increased considerably (three to fourfold). The AT III expression vectors carrying the hCMV enhancer were used to establish stable BHK cell-lines by a new and fast G418/methotrexate selection protocol, which express up to 12 micrograms AT III/10(6) cells/24h after 40-50 days. The given system might be generally useful for the fast expression of recombinant proteins in mammalian cells, e.g. the screening of altered AT III molecules obtained by site directed mutagenesis.

Animals↗
PubMed1987

Monolayer characteristics and thermal behavior of natural and synthetic phosphatidylserines.

The monolayer properties and thermal behavior of different phosphatidylserines are presented. At neutral pH and 22 degrees C, saturated phosphatidylserines form condensed monolayers while unsaturated phosphatidylserines form liquid-expanded films. Under similar conditions, dimyristoylphosphatidylserine undergoes a transition from the liquid-expanded to the condensed state. At pH 4 and 22 degrees C, the surface pressure-area isotherms are shifted to smaller areas relative to the monolayers recorded at neutral pH. The condensation observed at pH 4 is close to that produced at pH 7.4 by the addition of 10 mM CaCl2. As regards the molecular packing in monolayers and the thermal behavior, 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS) and its ether analogue are similar, albeit not identical. Below 30 mN/m, monolayers of the ether analogue are even more condensed than those of DPPS. The order-disorder transition of the ether analogue occurs usually at higher temperatures than that of the diacyl compound. Sonicated phosphatidylserine dispersions consisting of small unilamellar vesicles show anomalous thermal properties compared to sonicated phosphatidylcholine dispersions. They exhibit sharp order-disorder transitions at similar or even slightly elevated temperatures compared to unsonicated phosphatidylserine dispersions. This anomaly is explained in terms of a pH gradient across the bilayer membrane of the small unilamellar phosphatidylserine vesicle. The internal surface pH is more acidic than the external pH, leading to some protonation of phosphatidylserine molecules. This in turn leads to a condensation of phosphatidylserine molecules on the inner bilayer surface. Such a gradient is proposed to be responsible for the thermodynamic stability of highly curved negatively charged bilayer vesicles.

Hydrogen-Ion Concentration↗
PubMed1987

Infrared studies of fully hydrated unsaturated phosphatidylserine bilayers. Effect of Li+ and Ca2+.

Infrared spectroscopy has been used to characterize the thermal-phase behavior of fully hydrated 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) as well as their interaction with Li+ and Ca2+. The order-disorder transition of POPS-NH4+ is at 17 degrees C; in the presence of Li+ a POPS-Li+ complex is formed, and the transition temperature of this complex is 40 degrees C. DOPS-NH4+ has an order-disorder transition at -11 degrees C, and unlike POPS the addition of Li+ has no effect on the thermal behavior of DOPS-NH4+. This indicates that the binding of Li+ to DOPS is negligible or very weak. Li+ binds to the phosphate and carboxylate groups of POPS, and as a result these groups lose their water of hydration. Li+ binding induces a conformational change, probably in the glycerol backbone of POPS; however, the conformation of the two P-O ester bonds remains gauche-gauche as in POPS-NH4+. Both POPS and DOPS form crystalline complexes with Ca2+. As a result of Ca2+ binding to the phosphate, this group loses its water of hydration and there is a conformational change in the P-O ester bonds from gauche-gauche to antiplanar-antiplanar. In contrast to the POPS-Li+ complex, the carboxylate group remains hydrated in the Ca2+ complexes. Furthermore, in these PS-Ca2+ complexes a new hydrogen bond is formed between one of the ester C=O groups and probably water. Such a situation is not found in the NH4+ and Li+ salts of phosphatidylserine.

Calcium↗
PubMed1987

Infrared studies of fully hydrated saturated phosphatidylserine bilayers. Effect of Li+ and Ca2+.

The thermotropic phase behavior of fully hydrated Na+ and/or NH4+ salts of 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS) was determined by temperature-dependent infrared spectra. The molecular level properties and thermal phase behavior of DMPS-Li+ complexes were also characterized by infrared spectroscopy. With increasing concentrations of Li+, the infrared spectra reveal the appearance of a second, more ordered, lipid phase which shows a gel to liquid-crystal transition at significantly higher temperatures (75-95 degrees C) than the Na+ or NH4+ salts of DMPS (39 degrees C). Li+ binds to the phosphate and carboxylate groups of DMPS, resulting in the following changes: (1) water of hydration is lost from both the carboxylate and phosphate groups; (2) there are changes in the conformation of the glycerol backbone but not in the P-O ester bonds of the phosphate group which remain in the gauche-gauche conformation; and (3) the packing of the fatty acyl chains becomes more ordered. In addition, the properties of the DMPS-Ca2+ complex were studied by infrared spectroscopy. While the DMPS-Ca2+ complex is also characterized by rigidly packed, well-ordered fatty acyl chains, the mode of Ca2+ binding to the DMPS head groups differs significantly from that of Li+ binding. By comparison, with dry DMPS-Ca2+ [Casal, H. L., Mantsch, H. H., Paltauf, F., & Hauser, H. (1987) Biochim. Biophys. Acta (in press)], the phosphate group undergoes a conformational change, probably to the antiplanar-antiplanar conformation, and loses its water of hydration.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1987

Cooperative interaction of multiple DNA elements in the human interferon-beta promoter.

Analysis of promoter mutants and hybrids in permanently transformed murine L cells reveals several regulatory DNA sequence elements in the 5' flanking region of the human interferon-beta gene, which together constitute the inducible promoter. The elements consist almost exclusively of purine runs in the region -111 to -1. Deletion of single elements reduces the expression capacity drastically, whereas duplication leads to a synergism of inducible expression. These elements act together in a cooperative way to achieve high inducibility. Natural and mutant promoter fragments containing these elements impose inducibility on a heterologous promoter. However, typical enhancer activity in this system is not observed.

Animals↗
PubMed1987

Infrared and 31P-NMR studies of the effect of Li+ and Ca2+ on phosphatidylserines.

Infrared and 31P-NMR spectra of solid samples of 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) have been recorded. Comparison of the spectra of the Na+ salts of these phospholipids with those of complexes formed with Li+ and Ca2+ ions allows the characterization of conformational changes induced by complexation with Li+ and Ca2+. Ca2+ forms tight, crystalline complexes with these phosphatidylserines (PS), irrespective of the degree of unsaturation in the hydrocarbon chains. In these PS-Ca2+ complexes the torsion angles of the two P-O ester bonds exhibit the antiplanar-antiplanar conformation which is significantly different from the standard gauche-gauche conformation commonly found in phosphodiesters. In contrast, complexation with Li+ does not induce this conformational change in the phosphodiester group. It is shown that the degree of unsaturation in the hydrocarbon chains, and related to it, the cross-sectional area of the phospholipid or the surface charge density, determine the affinity of the phosphatidylserine for the metal ion. In general, the affinity of phosphatidylserines for both Li+ and Ca2+ decreases with increasing unsaturation in the hydrocarbon chains or decreasing surface charge density; it is in the order DMPS greater than POPS greater than DOPS.

Ammonia↗
PubMed1987

Superinduction of the human interferon-beta promoter.

Superinduction, that is induction with simultaneous blocking of mRNA translation, enhances the induction of interferon-beta in response to virus or double-stranded RNA in human fibroblasts. Expression of the cloned IFN-beta gene upon transfer into heterologous cells reflects the endogeneous interferon expression with respect to induction or superinduction indicating the involvement of cellular mediators in this mode of gene regulation. Expression from gene hybrids in mouse Mo57/2 cells reveals that 5' flanking DNA sequences from the human IFN-beta gene are responsible for induction and superinduction. Superinduction of the human IFN-beta promoter is demonstrated in several rodent and primate cell lines. In addition, expression from promoter mutants in mouse cells indicates that DNA sequences responsible for induction and superinduction are identical.

Animals↗
PubMed1987

NMR relaxation times T1 and T2 of water in plasma from patients with lung carcinoma: correlation of T2 with blood sedimentation rate.

The T1 and T2 NMR relaxation times of water protons in plasma, obtained from patients with lung carcinoma, healthy volunteers, and patients with nontumor diseases were measured at a resonance frequency of 20 MHz. Additionally hematologic parameters were determined. In tumor patients the mean plasma T2 was shortened by about 20%, and an increase in the blood sedimentation rate (BSR) was noted. Similar but less pronounced results were found for the nontumor group of patients, indicating that the shortening of T2 in plasma is a secondary host response. However, a plot of plasma 1/T2 versus BSR from tumor patients showed a significant correlation between these two parameters. No such correlation could be detected in the nontumor group of patients. The correlation of 1/T2 with BSR, found solely in the tumor patient group, increased the diagnostic sensitivity of T2 measurements and may help to differentiate between malignant and nonmalignant disease. No significant variation in the T1 spin-lattice relaxation time was observed.

Adult↗