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Biomedical subjects

H Hauser

Publications and source records attributed to H Hauser.

At least 235 records · Page 13Linked to original sources
PubMed1983

Sucrase-isomaltase: a stalked intrinsic protein of the brush border membrane.

The isolation and purification of sucrase-isomaltase from brush border membrane is described and the physicochemical properties of the pure enzyme are discussed. Our present understanding of the mode of association of the intrinsic membrane protein sucrase-isomaltase with the brush border membrane will be the central point of this contribution. The assembly of sucrase-isomaltase into phospholipid bilayers has been reported to result in a model membrane system which resembles the "native" brush border membrane as regards the mode of lipid-protein interaction. The physicochemical properties of this reconstituted model membrane will be compared to the in vivo situation as represented by brush border membrane vesicles routinely isolated from small intestinal brush borders. The biosynthetic mechanism will be discussed.

Amino Acids↗
PubMed1983

[Marfan's syndrome. Aortic complications studied by scanography].

Of all the pathological forms and variations of Marfan's syndrome, aortic aneurysm is one of the most important because of the high risk of medial dissection caused by cystic necrosis. The value of computerised axial tomography in the diagnosis of the aortic lesions of Marfan's syndrome was assessed in three clinical cases. Compared to angiography and echocardiography, computerised tomography avoids arterial catheterisation while demonstrating all anatomical changes of the aorta, coronary arteries, pericardium and mediastinum, with significantly less radiation. The point of entry of the dissection was not visualised in two of the cases presented. Therefore, computerised axial tomography should be considered in patients with Marfan's syndrome.

Adult↗
PubMed1983

[Value of computer tomography compared to angiography and echocardiography in the diagnosis of intracardiac thromboses].

Until recently the only means of diagnosing intracardiac thromboses were angiography and M mode and 2D echocardiography. The aim of this study was to assess the value of CAT scanning in this field and to compare it with angiography and ultrasonography. Twenty intracardiac thromboses were studied in 19 patients by CAT scanning: 14 in the left ventricle, 2 in the right ventricle, and 4 in the left atrium, one patient having both left and right ventricular intracavitary thrombosis. M mode and 2D echocardiography and angiography were carried out whenever possible. Although for different practical reasons all patients did not undergo all three investigations, CAT scanning appeared to be the most reliable diagnostic method in intracardiac thrombosis, being more specific than either angiography and ultrasonography. In addition, the therapeutic effects of anticoagulant therapy on the thrombus can be assessed and other associated pathology such as aneurysm, pericardial reaction, dilatation of the cardiac cavities, myocardial and valvular calcification can also be demonstrated.

Adult↗
PubMed1983

A Ga-68-labeled tetrabromophthalein (Ga-68 BP-IDA) for positron imaging of hepatobiliary function: concise communication.

We describe the chemical synthesis of an iminodiacetic-acid-substituted tetrabromo-o-cresolphthalein (BP-IDA), which complexes Ga-68 tightly. The liver uptake, bile excretion, and urinary excretion of the complex were examined in rats. Maximum liver uptake reached 60%, and 1-hr cumulative bile excretion was 75% of injected dose. Urinary excretion in rats with ligated common bile duct remained below 1%. Competitive action of exogenous bilirubin on hepatobiliary excretion of the Ga complex was less pronounced than that of bromosulfophthalein. The absolute activity determination of the positron emitter Ga-68, the high accumulation in the liver, the low urinary excretion, and the weak competition from exogenous bilirubin are promising features of this radiopharmaceutical for the quantitative study of hepatobiliary function.

Animals↗
PubMed1983

Myonecrosis induced by drug overdose: pathogenesis, clinical aspects and radiological manifestations.

The authors report five cases of myonecrosis varying in degree of severity and extent of the lesions, following drug overdose in young patients. The pathogenesis of this condition is discussed with reference both to the literature and the radiological findings of the present study. The clinical and radiological manifestations are described and a possible differential diagnosis is suggested, based on these data. Semeiologic data obtained by ultrasound and computerized tomography was found to give the most accurate information concerning the morphological characteristics of myonecrosis while ultrasound can reveal the extent of the involvement in the limbs.

Adult↗
PubMed1983

CT of the thoracic duct.

The ability of computed tomography to demonstrate the normal anatomy of the thoracic duct was investigated after lymphangiography in 20 patients without evidence of chest diseases on the plain films. The entire opacified thoracic duct can be easily imaged from its origin at the thoraco-abdominal level, up to its arch, which enters the venous blood stream, usually at the left subclavian-jugular confluent. Variations of the arch of the duct have been observed in our series. The ability to detect the non-opacified duct with CT was also assessed in 80 patients. Imaging of part or totality of the lower, mid and upper segments of the thoracic duct is possible respectively in 81, 54 and 69 per cent of subjects. The arch of the duct was displayed in 57 per cent. Knowledge of the normal anatomy of the thoracic duct is important since it can be involved in many diseases of the posterior mediastinum and of the thoracic outlet.

Adult↗
PubMed1982

Orientation and motion of spin-labels in rabbit small intestinal brush border vesicle membranes.

The temperature dependence of the packing (order) and fluidity (microviscosity) of rabbit small, intestinal brush border vesicle membranes and of liposomes made from their extracted lipids has been investigated by using a variety of lipid spin probes. The lipids in the brush border membrane are present essentially as a bilayer. Compared to other mammalian membranes, the brush border membrane appears to be characterized by a relatively high packing order as well as microviscosity. At body temperature, the lipid molecules undergo rapid, anisotropic motion, which is essentially a fast rotation about an axis approximately perpendicular to the bilayer normal. Both the order (motional anisotropy) and the microviscosity increase with decreasing temperature and with increasing distance from the center of the bilayer. Qualitatively similar motional or fluidity gradients have been reported for other mammalian and bacterial membranes. The liposomes made from the extracted lipids have a somewhat lower packing order and a slightly higher fluidity than brush border vesicle membranes. The differences are, however, small indicating that the packing and the fluidity (microviscosity) of the membrane are primarily determined by the lipid composition. Membrane-associated proteins and cytoskeleton cannot play a dominant role in determining the order and fluidity of the lipid bilayer. Discontinuities are observed in the temperature dependence of various spectral parameters, the order parameter S, the rotational correlation time tau, and 2,2,6,6-tetramethylpiperidinyloxy partitioning. They are assigned to phase transitions and/or phase separations of the membrane lipids. These discontinuities occur at about 30, 20, and 13 degrees C for 5-doxyl-, 12-doxyl-, and 16-doxylstearic acid, respectively. The apparent transition temperature depends on the location of the spin probe along the bilayer normal, being higher the closer the probe is to the membrane surface. This indicates the possibility that chain melting is progressive and spreads with increasing temperature from the center of the membrane outward.

Animals↗
PubMed1982

Inducibility of human beta-interferon gene in mouse L-cell clones.

Transfer of a 36-kilobase piece of human DNA containing the beta-interferon (IFN-beta) gene into mouse Ltk-cells leads to transient expression of human interferon even without an exogenous inducer. A low level of human interferon expression is also found in most stable clones containing the transferred DNA. With double-stranded RNA or Newcastle disease virus (NDV) as inducer, human interferon expression is greatly increased. The induced transcript is identical to normal human IFN-beta mRNA. Neighbouring genes contained on the transferred DNA are co-induced but are not essential for the production of human interferon in mouse L cells.

Clone Cells↗
PubMed1982

Lipid-protein interactions. Effect of apolipoprotein A-I on phosphatidylcholine polar group conformation as studied by proton nuclear magnetic resonance.

Spin-spin coupling constants derived from high-resolution 1H NMR spectra of pure 1-myristoyl-sn-glycero-3-phosphocholine (MLPC) micelles and 60:1 mol/mol been analyzed in order to determine the effects of apoprotein on phosphatidylcholine (PC) polar group conformation. The shift ratios of the polar group proton resonances after addition of the paramagnetic shift reagent Fe(CN)6(3-) to the above MLPC systems, egg PC small unilamellar vesicles, and human HDL3 have been used to compare the PC polar group conformations in all systems. The location of the largely alpha-helical apo A-I molecules in the complex with MLPC was deduced from its effects on the chemical shifts and spin-lattice relaxation times (T1) of the well-resolved 1H resonances from the various parts of the lipid molecules. The data are consistent with the apo A-I molecules lying in the surface fo the MLPC micelle with their amphipathic, alpha-helical segments intercalated among the glycerophosphocholine groups of the lipid molecules so that aromatic amino acid side chains are interspersed among the lipid hydrocarbon chains. This leads to a spacing out of the glycerol backbones and immediately adjacent methylene groups of the MLPC molecules, thereby causing an enhancement of the motions affecting T1. The presence of apo A-I at the lipid-water interface apparently does no perturb the PC polar group conformation, indicating that this conformation is determined by intramolecular effects. The preferred conformation of the phosphocholine group (Hauser, H., Pascher, I., Pearson, R. H., & Sundell, S. (1981) Biochim. Biophys, Acta 650, 21-51] is characterized by an almost exclusively gauche conformation of the choline group and predominantly antiperiplanar conformations about the C-C-O-P and P-O-C-C bonds. The PC molecules in MLPC micelles, MLPC-apo A-I complexes, egg PC vesicles, and HDL3 all have this polar group conformation.

Apolipoprotein A-I↗
PubMed1982

Structure and thermotropic behavior of phosphatidylserine bilayer membranes.

The structure and thermotropic properties of a homologous series of diacylphosphatidylserines (PS) in the anhydrous and hydrated states have been examined with low-angle X-ray diffraction and differential scanning calorimetry. In the anhydrous state at low temperatures both acidic PS and its NH4+ salts exhibit lamellar bilayer crystal forms that transform to liquid-crystalline hexagonal (type II) structures at higher temperatures. The crystal leads to liquid-crystal transition temperature increases with increasing chain length, the transition temperature of an NH4+-PS being higher than that of its corresponding acidic form. In contrast, the transition enthalpies of the acidic PS are higher than those of the NH4+ salt forms. Hydrated cyclic PS and NH4+-PS exhibit reversible lamellar gel leads to liquid-crystal transitions. In this case the acidic form undergoes this chain length dependent transition at a higher temperature, but with a lower enthalpy change, than the NH4+-PS. Both below and above the hydrocarbon chain melting transition, hydrated lamellar bilayer structures are present. The temperature-composition phase diagram of the NH4+-dimyristoyl-PS/H2O system has been studied in detail. The chain melting transition decreases with increasing hydration, reaching a limiting value of 39 degrees C. X-ray diffraction shows that both the bilayer gel structure and the bilayer liquid-crystal form take up water continuously (i.e., no hydration limit), a characteristic of lipid bilayers with a net charge. Electron-density profiles a NH4+-dimyristoyl-PS at different hydration levels permit detailed analysis of the structural parameters of the PS bilayer.

Calorimetry↗
PubMed1982

Gene shuttling: moving of cloned DNA into and out of eukaryotic cells.

Successful shuttling of cloned DNA in eukaryotic cells should allow isolation of expressed genes. We tested the utility of cosmids for moving DNA into and out of eukaryotic cells. The unique cleavage of DNA at the cos site by the terminase function of lambda was exploited to maintain the linkage between the vector and inserted gene sequences, a prerequisite for successful rescue of the transforming DNA from high molecular weight DNA of the eukaryotic transformant. A cosmid recombinant containing the HSV thymidine kinase gene and a lambda recombinant containing the chicken thymidine kinase gene were used to test the feasability of this method. It was found that these recombinants can be rescued with high efficiency from DNA of HAT-resistant cells.

Animals↗
PubMed1982

[Validity of computed tomography for the demonstration of patent or occluded aortocoronary vein grafts. A multicenter study].

In 328 patients with 611 aortocoronary bypass grafts CT was performed and 96 of them with 199 grafts were additionally studied by angiography. The results showed a sensitivity of 92,6%, a specificity of 78,1% and an overall accuracy of 87,9% for CT, which proved to be a reliable method for non-invasive direct visualization of aortocoronary bypass grafts. It can be performed within few days after surgery and also in out-patients as a follow-up study. Graft occlusion demonstrated in CT should be verified by angiography, whenever it results in a therapeutic consequence. Conversely if CT reveals patency of the graft, an angiographic control study is not necessary.

Adult↗
PubMed1982

Spontaneous vesiculation of phospholipids: a simple and quick method of forming unilamellar vesicles.

Phosphatidic acid dispersions in H2O vesiculate when the pH is increased transiently (less than 2 min) from approximately 3 to 10.5-11. The same phenomenon is observed in mixed dispersions of phosphatidylcholine and phosphatidic acid in H2O when the pH is increased from approximately 3 to 7 to 8. With phosphatidic acid, this treatment produces small closed unilamellar vesicles (200-600 A) from 50-60% of the total phospholipid, with the remainder present as large unilamellar vesicles and multilamellar structures. The extent of vesiculation depends on the pH that the dispersion is exposed to. With mixed phospholipid dispersions, similar vesicles are obtained; in addition to pH, the extent of vesiculation depends on the phosphatidylcholine/phosphatidic acid (wt/wt) ratio; as this ratio increases, the percentage of small unilamellar vesicles formed decreases. The short exposure of the phospholipids to high pH does not cause lipid degradation, as assessed by thin-layer chromatography; hence, the formation of degradation products can be ruled out as being responsible for the spontaneous vesiculation. Ionization of the phosphate group, resulting in a high surface charge density, may be an important factor in the spontaneous vesiculation. The proportion of phospholipid present as small unilamellar vesicles was determined by gel filtration on Sepharose 4B and by 1H NMR. The small vesicles gave rise to a reasonably well resolved high-resolution NMR spectrum. A good correlation was found between the proportion of phospholipid giving rise to the high resolution spectrum, as derived from spectral intensity measurements, and the proportion present as small unilamellar vesicles, as derived from gel filtration.

Freeze Fracturing↗
PubMed1982

Computed tomography of intramural hematoma of the small intestine: a report of 3 cases.

CT findings in 3 cases of intramural hematoma of the small intestine are described. One patient needed surgery. CT characteristics were specific and included a region of increased density (50-80 H) representing the hematoma. The differential diagnosis includes tumor (lymphoma or melanoma) and inflammatory disease (Crohn disease or pancreatic cyst).

Adult↗
PubMed1982

[Value of echocardiography in the diagnosis of Uhl's disease. Apropos of a case in an adult].

Uhl's anomaly, or paper thin right ventricle is a rare congenital malformation which may present with variable degrees of hypoplasia. The most severe forms are encountered in infants and children, but a less serious form occurs in adolescents and adults which, clinically. There are a number of echocardiographic features common to both diseases but paper-thin right ventricle may be distinguished by the finding of premature opening of the pulmonary value. The increased atrial contraction in these patients with right ventricles of reduced compliance is directly transmitted to the pulmonary artery, leading to end diastolic opening of the pulmonary value before tricuspid closure. The case presented underlines the value of M mode echocardiography in the diagnosis of Uhl's anomaly and in the differential diagnosis with Ebstein's anomaly.

Diagnosis, Differential↗
PubMed1982

Diagnosis of alimentary tract perforation by CT.

The roentgenologic diagnosis of digestive tract perforation is based primarily on evidence of free air shown on a standard abdominal film. However, this finding may not be present, especially during the first hours following trauma. This retrospective study of 10 patients shows that the anatomical precision of computed tomography can help greatly in detecting small collections of free air, in addition to other abdominal changes. Although CT is commonly requested for a cause of acute abdomen other than suspected perforation, the radiologist must also look carefully for a small collection of free air or other signs that may indicate free air.

Abdomen, Acute↗