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Biomedical subjects

B Müller

Publications and source records attributed to B Müller.

At least 361 records · Page 20Linked to original sources
PubMed1990

Quantitative Determination of Allicin and Alliin from Garlic by HPLC*.

The procedure for allicin synthesis could be improved. The time for HPLC analysis of allicin was shortened by the application of different isocratic elution systems. Calibration was performed by use of an allicin/silica gel adsorbate as external standard and its allicin content could be confirmed by different methods. L-(+)-Alliin was synthesized and applied as external standard for the quantitative determination of alliin by HPLC. Diastereoisomers had been separated by repeated recrystallization. Fresh ALLIUM SATIVUM bulbs from different origins were analyzed with respect to allicin content after complete enzymatic conversion of alliin; allicin contents found were in the range of 0.4%. The corresponding alliin contents were in the range of 0.9%. For a comparative evaluation of the alliin- and the allicin-HPLC determination methods, commercially available garlic preparations were analyzed, demonstrating that both methods are appropriate. However, the application of the HPLC system for allicin determination, in addition to providing information on the alliin-dependent allicin-generating capacity, enables the simultaneous quantification of allicin transformation products, such as ajoenes, dithiins, and alkyl sulfides. It was found that, for quantitative GLC analysis of allicin, allicin has to be used as an external standard.

Journal Article↗
PubMed1990

Theoretical considerations on germline mosaicism in Duchenne muscular dystrophy.

A newly formulated mutation selection equilibrium for lethal X linked recessive traits such as Duchenne muscular dystrophy is presented, which allows for both male and female germline mosaicism. Estimates of the additional parameters used are given, thus allowing the incorporation of germline mosaicism into the calculation of genetic risks.

Female↗
PubMed1990

In vitro experiments on axonal guidance and growth-cone collapse.

In the retinotectal projection, nasal retinal axons project to posterior tectum, while temporal axons project to the anterior part of the tectum. In in vitro experiments, a similar specificity can be observed: the nasal and temporal retinal axons can be guided by tectal membrane components so that, for example, temporal retinal axons, when growing on a striped substratum consisting of anterior and posterior tectal membranes, express a very strong preference for the anterior stripes. This preference is not due to attractivity of anterior membranes but rather to avoidance of posterior material, although the pure posterior membranes are a very good substratum for growth of temporal axons. The repellent guidance molecule has been identified. Interestingly, besides guidance this molecule causes another reaction: when growing temporal axons are exposed to medium containing either posterior membranes or artificial lipid vesicles containing the repellent guidance molecule, the axonal growth cones collapse. As in guidance, there is a clear regional specificity: e.g. the repellent guidance molecule derived from posterior tectum induces collapse of temporal but not of nasal axons. Since the guiding and the collapse-inducing activity are expressed by one and the same glycoprotein molecule (Mr 33 x 10(3), linked to the membrane by phosphatidylinositol) and since another molecule has been identified by Keynes' group which also expresses both guiding and collapse-inducing activity, one might speculate that axonal guidance and axonal collapse have something in common. Models of axonal guidance will be discussed.

Animals↗
PubMed1990

Iloprost antagonizes endothelin-induced vasoconstriction in macro- and microcirculation.

In conscious Wistar rats, endothelin (ET-I) caused a dose-dependent long-lasting blood pressure increase, which was more pronounced after indomethacin pretreatment. The initial blood pressure drop was also enhanced after indomethacin. The stable prostacyclin analogue iloprost completely reversed the pressor effect of endothelin. In the hamster cheek pouch, ET-I caused a rapidly developing, long-lasting constriction of arterioles, which could be completely reversed by iloprost. The results demonstrate that prostacyclin can act as a potent functional antagonist of endothelin-induced systemic and local pressor responses.

Animals↗
PubMed1990

[Multifocal bronchial cancer].

Since the entire surface of the bronchial mucosa is exposed to carcinogenic stimuli, the possibility of developing multiple primary lung carcinomas must be discussed. Multiple primary lung carcinomas do not necessarily occur simultaneously (synchronous), they can also develop successively (metachronous). They can be localized ipsilateral as well as contralateral, and histologically they have an identical or different character. In our study of 612 patients with bronchogenic carcinoma we found 18 patients (2.9%) to have a synchronous multiple primary carcinoma. The growing clinical relevance of the diagnosis of the multiple primary bronchogenic carcinoma--which is certainly diagnosed to rarely--and the distinction from metastases will be discussed.

Adult↗
PubMed1990

[What is the place of "selective thyroid gland resection" in surgery of benign nodular struma].

Remnants after "classic" Subtotal Thyroidectomy are of constant size in constant position. "Selective" thyroidectomy intends to remove all nodules, but to save normal tissue--irrespective of their localization. From July 1985 to Dec. 1989 in 48.5% of 1124 thyroid lobes sel. surgery was performed, in 27.8% subtotal, in 23.8% total lobectomy. Primary postop. recurrent lar. palsy occurred in 1.3% after sel., 1.0% after subt. and 2.7% after total lobectomy. 90% of primary r.l.n.p.'s were transient--after sel. lobectomy only one persistend (0.2%). Hypocalcemia: 0.7% after sel., 1.4% after subt. thyroidectomy. Besides better quality and quantity of remnants selective thyroidectomy is supported by low rate of complications.

Goiter, Nodular↗
PubMed1990

Axonal guidance by an avoidance mechanism.

1. On a substrate consisting of alternating lanes of anterior and posterior tectal membranes, temporal retinal axons have a strong tendency to grow on the lanes of anterior membranes and to avoid the lanes of posterior membranes. 2. Temporal axons do extend neurites on posterior material, and in equivalent numbers and lengths to that of anterior membranes if the substrate consists of pure anterior or posterior membranes. 3. Inactivation of posterior membranes by heat or the enzyme phosphatidylinositol-specific phospholipase C (PI-PLC) abolishes their ability to induce the avoidance reaction of temporal axons. It is concluded that the posterior membranes contain a repulsive component for temporal retinal axons. 4. Growth cones growing on anterior membranes, which encounter posterior membranes at the strip boundary, in general do not become reduced in their growth rate. 5. These results are most easily explained by a "gradient-reading model" similar to chemotaxis where the steering of a growth cone is independent on the growth rate. 6. According to the model, a gradient of a guiding component outside the growth cone is transformed into an internal gradient which gives the growth cone its directionality. 7. Other models like growth inhibition cannot be ruled out but need at least two additional assumptions like habituation for growth on the putative posterior inhibitory substrate and a strong local restriction of the inhibitory effect within the growth cone which contacts the posterior material.

Animals↗
PubMed1990

[Resorption of iron in steady-state conditions following administration of Vitaferro to females with anemia in pregnancy and evaluation of hematologic and biochemical iron parameters].

Determination of ferritin is suitable for estimation of iron stores as well as for diagnosis of iron deficiency during pregnancy. It shall be used preventively in the 20th gestational week and to control treatment. Determinations of serum iron concentration, iron binding capacity and partial transferrin saturation are less suitable. Substitution of iron should start when a sufficient compensation of the iron deficiency is still possible. For this purpose Vitaferro is a suitable drug.

Administration, Oral↗
PubMed1990

Ultrastructural pathology of skeletal muscle in systemic lupus erythematosus.

Muscle biopsies from 12 patients with systemic lupus erythematosus (SLE) who presented with muscle weakness and myalgias were studied ultrastructurally. Two different alterations were present, myositis (11 cases), and vacuolar myopathy (1 case). The myositis exhibited muscle atrophy, microtubular inclusions, and a mononuclear cell infiltration. In one case, with increased serum creatine phosphokinase, fiber necrosis was evident. Capillary abnormalities included thickening and reduplication of basement membrane, alterations of endothelium and microtubular inclusions. The vacuolar myopathy also showed vacuolated muscle fibers and occasional zebra bodies. The different associations between muscle diseases and SLE are grouped. Our data suggest that SLE myositis is a distinct clinical and pathological entity. The SLE vacuolar myopathy is a pathological entity clinically undistinguishable from SLE myositis.

Capillaries↗
PubMed1990

[Effects of various oxygen concentrations on metabolic performance of in vitro perfused human placentas].

The aim of the experiments was the in vitro-investigation of metabolic reactions of human placentae under different oxygen supply, particularly when oxygenation followed a period of hypoxia. A perfusion system was used with both circuits of a whole placenta being recirculated over 2 hours with blood-containing perfusate. In group A 17 placentae were perfused under normoxic conditions; in group B 10 perfusions were carried out under hypoxia. In group C 8 placentae were oxygenated after 60 minutes of hypoxic perfusion. (All results are given in mumol/g wet weight/h). In group B glucose uptake (2.95 +/- 1.11) was slightly increased compared to group A (2.59 +/- 1.68), while lactate production was markedly higher (7.69 +/- 1.04 versus 3.56 +/- 1.53 in group A). Oxygen consumption was smaller under hypoxia. Pyruvate showed no significant changes over the 2 hours in all groups. In group C the results of the first hour resembled those of group B. After reoxygenation these placentae showed a smaller oxygen consumption compared to group A, but the highest glucose uptake (4.35 +/- 0.72), whereas lactate production (5.26 +/- 1.86) was lowered compared to group B. The smaller oxygen consumption could be explained by a deterioration of mitochondriae and hence a decreased capacity of oxydative metabolism. The higher glucose uptake could reflect the ability of placental tissue to restore other energy-sources (e.g. proteins) which were affected under the previous hypoxia. Further investigations are required to answer questions of placental function and its disturbances.

Blood Glucose↗
PubMed1989

Co-expression of the subunits of the heterodimer of HIV-1 reverse transcriptase in Escherichia coli.

Expression of the 66-kDa form of human immunodeficiency virus, type 1 reverse transcriptase in Escherichia coli leads to isolation of small amounts of a 2 x 66-kDa homodimer and larger amounts of a heterodimer form of the enzyme in which the 66-kDa protein is complexed with its carboxyl-terminally truncated is complexed with its carboxyl-terminally truncated 51-kDa form. The latter arises via proteolysis by contaminating proteases. The heterodimer, which was characterized by gel filtration (apparent native molecular mass of 120-130 kDa), was the most active form of the enzyme (specific activity, 5000 units/mg, cf. less than 2000 for the 66-kDa fragment). The 66-kDa fragment alone was shown to be only partially dimerized, with the activity residing mainly in the dimer fraction. Proteolysis of the 66-kDa form resulting partially in the 51-kDa form led to an increase in reverse transcriptase activity. Expression of a truncated version of the protein containing the first 428 amino acids of the reverse transcriptase coding region led to a protein which had low but measurable reverse transcriptase activity (400-500 units/mg). Co-expression of the two proteins on a single plasmid led to expression in a 1:1 ratio. The 1:1 mixture behaved as a heterodimer, as shown by its chromatographic properties. It is likely that the mechanism for the production of heterodimers in vivo involves cleavage of 66-kDa monomers followed by rapid dimerization of the 51- and 66-kDa forms to give the heterodimeric form, which is stable toward further proteolysis.

Catalysis↗