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Biomedical subjects

M Braun

Publications and source records attributed to M Braun.

At least 19 recordsLinked to original sources
PubMed1992

Changes in mononuclear peripheral blood cells in cattle with foot-and-mouth disease.

The percentages and absolute numbers of mononuclear peripheral blood cells (MNC) were studied in vaccinated (Vac) and non-vaccinated (control) cattle, challenged with foot-and-mouth disease virus (FMDV). All Vac cattle but none of the controls resisted challenge. Cell populations were studied immediately before and one week after challenge, by direct and indirect immunofluorescence, using polyclonal and monoclonal antibodies against different bovine markers. Total B-lymphocytes, as assessed with polyclonal anti-IgG (H + L) antisera, as well as total mononuclear cells, were normal before and after infection, and did not change in Vac or control groups. Before challenge Vac cattle had higher numbers of ILA-29+ (a putative marker for null cells or, alternatively, for gamma delta T-cells) than control cattle. After challenge, in control cattle, the number of total T-cells, BoT4-bearing (helper) T-cells and BoT8-bearing (cytotoxic/suppressor) T-cells were decreased, while IgM-bearing B-lymphocytes, as well as monocyte/macrophage cells were increased. The number of IL-A29-bearing T-cells did not change after infection in either group. After challenge, Vac cattle also showed increased numbers of IgM-bearing B-lymphocytes and monocyte/macrophage cells, whereas T-subpopulations did not change significantly.

Animals↗
PubMed1992

Antiatherosclerotic properties of oral cicaprost in hypercholesterolemic rabbits.

The effects of the orally active prostacyclin mimetic cicaprost on morphologic and functional alterations of rabbit aorta was investigated in experimental hypercholesterolemia. Oral cicaprost resulted in a significantly reduced aortic atheromatous plaque formation and partially prevented hypercholesterolemia-induced impairment of endothelium-dependent relaxations. It is concluded that long-term substitution with PGI2 may beneficially influence the progression of atherosclerosis.

Administration, Oral↗
PubMed1992

A comparative study of the anatomical, radiological and therapeutic features of the lumbar facet joints.

An anatomical study of the lumbar apophyseal joints was carried out to facilitate recognition of facet joint lesions, which we now examine routinely by percutaneous arthrography. Special attention was given to the configuration of the different compartments of the joint space and to its relationships with the contents of the intervertebral foramen. The abnormalities seen on lumbar facet joint arthrography are very varied; two major groups should be stressed: synovial fringe hypertrophy and pseudodiverticular synovial ectasia. The percutaneous approach to lumbar facet joint arthrography allows it to be used a therapeutic measure, with injection of anti-inflammatory drugs into the joint space, the beneficial effects of which were confirmed in our series. The precision, efficiency and cost-effectiveness of this outpatient technique justify and should encourage its more widespread application in the diagnosis and treatment of low back pain.

Adult↗
PubMed1992

Compression and reconstruction of MRI images using 2D DCT.

In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be compressed using the discrete cosine transform (DCT). We present here a method of treating the data that combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.

Fourier Analysis↗
PubMed1992

[Value of transcranial Doppler ultrasonography in patients with suspected brain death].

Transcranial Doppler ultrasonography (TCD) is a non invasive technique which assesses blood flow velocitics in basal cerebral arteries. Specific patterns have been observed in brain death. In a continuous series of 72 patients, the TCD recordings from the intracranial internal carotid and middle cerebral arteries were compared with the results from the usual investigations for brain death, such as electroencephalogramme (EEG), and arteriography. All the patients were clinically brain dead: Glasgow score of 3, apnoea, bilateral mydriasis, loss of cortical function and cerebral reflexes. This clinical diagnosis was confirmed by and isoelectric EEG with or without angiographic circulatory arrest. Two characteristic patterns were identified: an oscillating to and fro signal, with a positive sharp systolic peak and a negative diastolic reflux; and a systolic peak without any diastolic component. The absence of signal on both sides did not allow any conclusion, except when this pattern occurred during follow-up. The oscillating pattern was seen on both sides in 60 patients (83%), and, in 3 other patients, only on one side, always combined with a contralateral systolic peak pattern, in 3 other patients. A bilateral systolic peak pattern was identified in 7 patients (10%). The TCD results were compared with angiography in 37 cases. TCD circulatory arrest preceded angiographic arrest by six hours in three cases. Hypotension was the main limitation to this technique. n the other hand, TCD may be used in patients treated with sedative drugs. The non invasive character of TCD, its low cost, the possibility of repeating it at the patient's bedside make TCD a very interesting diagnostic tool.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Prostaglandin D2 relaxes bovine coronary arteries by endothelium-dependent nitric oxide-mediated cGMP formation.

This study investigates the vasomotor activities of prostaglandin (PG) D2 in bovine coronary arteries in relation to endothelial function. Isolated segments of bovine coronary arteries with intact endothelium were concentration-dependently relaxed by PGD2 (0.01-1 microM), a reaction that was blocked by a selective PGD receptor antagonist (BW A868C). There was a tight correlation between PGD2- and acetylcholine-induced relaxations (r = 0.894, n = 96, p < 0.001). Removal of endothelium abolished the PGD2-induced relaxation and unmasked a contractile activity of the compound. Inhibition of endogenous PGI2 formation by indomethacin did not modify these responses, whereas inhibition of endogenous nitric oxide generation by NG-nitro-L-arginine and NG-monomethyl L-arginine (10 or 100 microM) or scavenging of released nitric oxide by oxyhemoglobin (3 microM) considerably (> 50%) antagonized the PGD2-induced relaxation. The vessel relaxation by PGD2 was associated with a threefold to fourfold increase in vascular cGMP. A considerable reduction in vascular cGMP was measured after removal of the endothelium (by 53%) and inhibition of endogenous nitric oxide generation by NG-nitro-L-arginine (by 70%). This also resulted in a complete inhibition of PGD2-induced cGMP accumulation. Similar results were obtained with the stable PGD2 mimetic ZK 110.841, suggesting that these biological activities of PGD2 were due to the compound itself and not caused by any PGD2 metabolite. A slight but significant increase in cAMP was observed in arteries with intact endothelium as well as after removal of endothelium. Because the relaxing effect of PGD2 was strictly endothelium dependent, the observed relaxation cannot be explained by cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[MRI exploration of the hypothalamo-hypophyseal axis].

MR Imaging has become the procedure of choice for the exploration of the pituitary region. MR contrast resolution is far better than the finest CT examination, especially concerning the microadenomas and the neurohypophysis. The present paper concerns, at first the major principles of magnetic resonance imaging, its application for the study of the pituitary region including the use of contrast agent (Gadolinium). Lastly, MR anatomy and physiological variations are presented.

Adolescent↗
PubMed1992

An efficient algorithm for MR image reconstruction and compression.

In magnetic resonance imaging (MRI), the original data are sampled in the spatial frequency domain. The sampled data thus constitute a set of discrete Fourier transform (DFT) coefficients. The image is usually reconstructed by taking inverse DFT. The image data may then be efficiently compressed using the discrete cosine transform (DCT). We present here a method of using DCT to treat the sampled data, which combines two procedures, image reconstruction and data compression. This method may be particularly useful in medical picture archiving and communication systems (PACS) where both image reconstruction and compression are important issues.

Algorithms↗
PubMed1992

Brain tissue heterotopia in the nasopharynx. Contribution of MRI to assessment of extension.

The authors report two cases of brain tissue heterotopia in the nasopharynx, without other malformations and, in one of the cases, with a persistent craniopharyngeal canal opening onto the heterotopia. This exceptional malformation is very similar to brain heterotopia in the nose, or "nasal glioma", which is more frequent and less diversified at histology. The malformation is revealed by obstruction of the pharynx with respiratory distress immediately after birth or during the first weeks of life. Total surgical excision provides cure without sequelae. The diagnosis is based on histology. MRI is essential to the diagnostic and pretherapeutic evaluation, notably to avoid missing an ectopic hypophysis, but it is insufficient to diagnose a sphenoidal meningoencephalocele.

Brain↗
PubMed1992

Crohn's disease of the duodenum complicated by pancreatitis and common bile duct obstruction.

It is well known that Crohn's disease can involve the duodenum, but isolated secondary complications such as pancreatitis or common bile duct obstruction have only rarely been reported, and never in the same patient. Herein, we describe a patient with duodenal Crohn's disease and both pancreatitis and calculous common bile obstruction. This unusual constellation of findings was managed with percutaneous techniques in which transhepatic catheterization of the bile duct permitted balloon dilatation of the ampulla of Vater, as well as a duodenal stricture. These maneuvers resulted in passage of the biliary stone and relief of the patient's symptoms. The management of this patient may serve as a guide possibly to delay or even prevent surgical intervention in similar cases of benign enteric strictures.

Adult↗
PubMed1991

12 alpha-hydroxysteroid dehydrogenase from Clostridium group P, strain C 48-50. Production, purification and characterization.

NADP(H)-dependent 12 alpha-hydroxysteroid dehydrogenase (HSDH) from Clostridium group P, strain C 48-50, is still expressed at unusual high level (approximately 1% of total protein) under cultivation conditions where the usual expensive brain/heart infusion complex medium is replaced by inexpensive technical grade yeast autolysate. An inexpensive anaerobic bioprocess for the production of HSDH was developed provisionally up to 900-1 scale (9000 U/l, 7 g HSDH, specific activity 1.0 U/mg crude protein, 55 U/g wet cells). By a simple two-step affinity chromatography procedure, easily adaptable to a large-scale operation, using columns of small dimensions of Sephacryl-S-400-Procion-orange-P-2R (5 cm x 28 cm) and Sephacryl-S-400-Procion-red-HE-7B (2.6 cm x 14 cm) approximately 140 mg (1.8 x 10(4) U), HSDH was purified to apparent homogeneity and concentrated directly from a crude cell extract (overall yield 53%, specific activity 128 U/mg). As confirmed by fast native and SDS/PAGE, isoelectric focussing and electron microscopy, HSDH has a molecular mass of approximately 105 kDa and consists of four flattened tetrahedrically arranged identical subunits (26 kDa). The enzyme exhibits a rather low isoelectric point of 4.6, a pH optimum of 8.5-9.5 and a temperature optimum of approximately 55 C for the oxidation of cholic acid. Inhibition by SH reagents and pyridoxal 5'-phosphate has been observed. Chelating agents have no inhibitory effect. The presence of NADP increases considerably the thermostability (t 1/2 4-10 d, 25 C; 2-5 d, 37 C). Steady-state kinetic analysis for both reaction directions indicated that the reaction proceeds through an ordered bi bi mechanism with NADP(H) binding first to the free enzyme. Km, Vmax [forward (Vf) and reverse reactions (Vr)] and the dissociation constants Kd for the binary complexes with NADP and NADPH were as follows. NADP, Km = 35 microns, Kd = 35 microns; cholic acid, Km = 72 microns, deoxycholic acid, Km = 45 microns, Vf = 160 U mg; NAPDH, Kd = 16 microns; 12-oxochenodeoxylic acid, Km = 12 microns, 66 U/mg (conditions, 0.1 M potassium phosphate, pH 8.0, 25 degrees C). N6-functionalized NADP derivatives, e.g. N6-(2-aminoethyl)NADP (Km = 4.5 mM) are poorly accepted as coenzyme by HSDH.

Amino Acid Sequence↗
PubMed1991

Image reconstruction from Fourier domain data sampled along a zig-zag trajectory.

When the conventional Fourier transform (FT) algorithm is applied to reconstruct a magnetic resonance (MR) image from data sampled along a zig-zag trajectory in the Fourier space, the nonuniform sampling in the spatial frequency direction may give rise to artifacts. In this paper the nature of the artifacts is analyzed and an alternative reconstruction algorithm is developed to produce artifact-free images. Methods for reducing noise level in the reconstructed image are discussed. Our approach is compared with another method based on the interlace sampling theorem.

Algorithms↗
PubMed1991

Animal experiments with a new dura graft (polytetrafluorethylene)--results.

A comparative animal experiment study on rabbits was performed to test a synthetic dura (expanded polytetrafluorethylene = ePTFE = Gore-Tex Surgical Membrane). For the purpose of comparison with the ePTFE implanted in the left hemisphere, lyophilized natural dura (Lyodura) was used and removed from the subjects after two, eight and twelve weeks. There were no rejection reactions. The lyophilized dura showed pronounced environmental reaction, with cellular permeation and indications of revitalization. The ePTFE manifested only slight reaction and remained inert in an enclosing sheath of connective tissue. The biocompatibility and other properties, such as simple handling and resteriliziability, of ePTFE can thus be assessed as positive.

Animals↗
PubMed1991

Increased plasma viscosity and erythrocyte aggregation: indicators of an unfavourable clinical outcome in patients with unstable angina pectoris.

OBJECTIVE: To determine the prognostic significance of altered plasma viscosity and erythrocyte aggregation in unstable angina. DESIGN: A prospective study of 96 consecutive patients with unstable angina allocated to one of two groups according to predefined threshold values for plasma viscosity and erythrocyte aggregation at study entry. The patients received a standardised treatment and were followed up for six months or until angioplasty or bypass surgery. MAIN OUTCOME MEASURE: Frequency of myocardial infarction. RESULTS: Myocardial infarctions occurred in 7/26 patients with a plasma viscosity greater than or equal to 1.38 mPa s and in 8/35 with a rate constant of erythrocyte aggregate formation greater than or equal to 0.5 mPa (corrected for plasma viscosity) but in only 4/70 with a plasma viscosity less than 1.38 mPa s and in 3/61 with an erythrocyte aggregation less than 0.5 mPa (odds ratios: 6.1 (95% confidence interval 1.3 to 31), p = 0.008, and 5.7 (95% CI 1.2 to 35), p = 0.016). Plasma viscosity and erythrocyte aggregation were more predictive of myocardial infarction than age, male gender, fibrinogen concentration, ST segment abnormalities, or coronary score. Furthermore, Holter monitoring with ST segment analysis showed that ischaemic episodes were more common in patients in whom the rate constant of erythrocyte aggregate formation was greater than 0.5 mPa (15/27 v 17/50, p = 0.029). Cardiac troponin T release was increased in patients with a plasma viscosity of greater than 1.38 mPa s (10/26 v 9/70, p = 0.010). CONCLUSIONS: In patients with unstable angina a considerable increase in plasma viscosity and erythrocyte aggregation identified a subgroup of patients at a high risk of acute myocardial infarction in whom medical treatment was likely to be unsuccessful.

Aged↗
PubMed1991

Arachidonic acid and early human growth: is there a relation?

Growth failure is a classical sign of essential fatty acid deficiency. We investigated whether birth weight correlates with the postnatal essential fatty acid status in a group of 29 premature infants. A significant and positive correlation between body weight and plasma triglyceride content of arachidonic acid (20:4n-6) (r = 0.47, p = 0.01) and total omega-6 long-chain polyunsaturated fatty acids (r = 0.49, p less than 0.01) was found. In contrast, there was no positive relation to linoleic acid (18:2n-6) or any omega-3 fatty acid but a significant inverse correlation to alpha-linolenic acid (18:3n-3). We propose that during early life arachidonic acid may have a growth-promoting effect which could be related to its role as an eicosanoid precursor or to its structural function in membrane lipids.

Arachidonic Acid↗
PubMed1991

Antiplatelet, antineutrophil and vasodilating properties of 13,14-dihydro-PGE1 (PGE0)--an in vivo metabolite of PGE1 in man.

The actions of the in vivo metabolite of PGE1, 13,14-dihydro-PGE1 (PGE0), on platelet and neutrophil (PMN) function and vessel tone were studied in vitro. PGE0 inhibited aggregation, ATP release and thromboxane generation by human platelets (IC50 10-100 nmoles/l). The compound also inhibited superoxide anion generation and lysosomal enzyme release from human PMN. PGE0 was equipotent to PGE1 in both systems, while 15-keto-PGE1 was ineffective in platelets but produced some inhibition in PMN. These inhibitory effects of PGE0 and PGE1 were paralleled by concentration-dependent increases in cyclic AMP in platelets and PMN. Both compounds were also potent relaxants of several arterial preparations in the rabbit at comparable concentrations. In general, the vasorelaxing properties of PGE0 were somewhat lower and the contractile effects somewhat stronger in comparison to PGE1. These data demonstrate a significant and concentration-dependent inhibition of receptor-mediated activation of human platelets and PMN by PGE0. The molar potency of the compound is comparable to that of PGE1. Generation of PGE0 from infused PGE1 may contribute to the clinical efficacy of PGE1 in treatment of severe peripheral arterial occlusive disease.

Alprostadil↗
PubMed1991

[The pharmacology of 13,14-dihydro-PGE1 in comparison with PGE1].

This study investigates the effects of 13,14-Dihydro-PGE1 (PGE0) in comparison to PGE1 on human platelets, human polymorphonuclear granulocytes (PMN) and a number of vessel preparations of different species. The potency of PGE0 in inhibition of platelet and neutrophil activation is similar to PGE1. The vascular action differs. At a comparable molar potency, PGE0 showed stronger contractile and less relaxing effects than PGE1. The biological activities of PGE0 may contribute to the in vivo effects of PGE1 in treatment of peripheral arterial occlusive disease, in particular at high-dose i.v. administration.

Alprostadil↗