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M Sieber

Publications and source records attributed to M Sieber.

At least 91 records · Page 5Linked to original sources
PubMed1989

Calcium channels reconstituted from the skeletal muscle dihydropyridine receptor protein complex and its alpha 1 peptide subunit in lipid bilayers.

In the first part of this study, we show that sDHPR and pDHPR preparations reconstituted into lipid bilayers formed on the tips of patch pipettes exhibit two divalent cation-selective conductance levels of 9 and 20 pS, similar in single-channel conductance to VSCC reported in a variety of intact preparations (see Pelzer et al. and Tsien et al. for review). The larger conductance level is similar to the VSCC identified in intact rat t-tubule membranes and described in sDHPR and pDHPR preparations, and shares many properties in common with activity from L-type VSCC. It is sensitive to augmentation by the DHP agonist (+/-)-BAY K 8644 and cAMP-dependent phosphorylation, and to block by the phenylalkylamine (+/-)-D600 and the inorganic blocker CoCl2. Its open-state probability and open times are increased upon depolarization as expected for a voltage-dependent activation process. Upon depolarization beyond the reversal potential, however, open-state probability and open times decline again. A reasonable way to explain the bell-shaped dependence of open times and open-state probability on membrane potential is to assume voltage-dependent ion-pore interactions that produce closing of the channel at strong negative and positive membrane potentials. By contrast, the smaller conductance level may be similar to the 10.6-pS t-tubule VSCC described by Rosenberg et al. and may best be compared with T-type VSCC. It is largely resistant to augmentation by (+/-)-BAY K 8644 and cAMP-dependent phosphorylation or block by (+/-)-D600, but is sensitive to block by CoCl2. Its open times and open-state probability show a sole dependence on membrane potential where depolarization increases both parameters sigmoidally from close to zero up to a saturating level. Both elementary conductance levels do not exhibit significant inactivation over a wide potential range, which may suggest that skeletal muscle VSCC inactivation is either poorly or not voltage-dependent at all. This possibility seems in agreement with bilayer recordings on reconstituted intact t-tubule membranes and voltage-clamp recordings on intact fibers. It supports the idea that the decline of Ca2+ current in intact skeletal muscle fibers may be due to Ca2+ depletion from the t-tubule system and/or to inactivation induced by Ca2+ release from the sarcoplasmic reticulum. We consistently observe two conductance levels of 9 and 20 pS, either singly, or together in the same bilayer from solubilized DHPR samples and even highly purified DHPR preparations.(ABSTRACT TRUNCATED AT 400 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Effects of body measurements and weight on calf size and calving difficulty of Holsteins.

Body measurements (heart and paunch girths, wither height, chest depth, pelvic length and width, and body length), body weight, and calving evaluation data (calf birth weight, calf sex, calf presentation, and calving assistance needed) were collected from 1974 parities of 762 Holstein cows between 1968 and 1986. Degree of calving assistance was scored continuously from 1 (no assistance) to 10 (hard mechanical assistance). Phenotypic correlations of dam body traits with calf birth weight were all significantly positive when combined for all parities and ranged from .23 for paunch girth to .27 for body weight and heart girth. Correlations of dam body traits with calving assistance scores were all significantly negative across parities and ranged from -.24 to -.30. Correlations of calf birth weight with calving assistance were higher for first parity (.37) than for all parities (.20). Least squares analysis showed that cows with shorter wither height and shorter pelvises tended to require more calving assistance. Heavier calves, winter calvings, and earlier parity all were related to increased dystocia. Male calves were heavier than female calves and also were associated with greater calving difficulty.

Animals↗
PubMed1989

[The significance of somatic and psychosocial factors for coping with illness by patients with multiple sclerosis].

The coping behavior of 298 multiple sclerosis patients was assessed by means of a questionnaire. Despite more pronounced somatic complaints, women view their psychological situation more positively than men; they are more optimistic, less anxious, less depressed, and less preoccupied with their illness and its consequences. In the event of reduced working capacity due to the disease, men are more frequently disabled than housewives. However, there is evidence that early disability compensation may have a negative effect on the psychological well-being and the coping behavior. Careful thought should therefore be given to the timing when the question of a pension is discussed.

Adaptation, Psychological↗
PubMed1988

cAMP-dependent protein kinase rapidly phosphorylates serine- 687 of the skeletal muscle receptor for calcium channel blockers.

The cAMP-dependent phosphorylation of the 165-kDa subunit of the receptor for organic calcium channel blockers (CaCB-receptors) was studied. Tryptic peptide analysis showed that cAMP-dependent protein kinase phosphorylates rapidly a serine in one peptide. Up to three peptides containing phosphoserine and -threonine are phosphorylated in a 2-h incubation. The isolated 165-kDa subunit was digested with trypsin and the endoproteinase Lys-C and Glu-C. The rapidly phosphorylated peptide was isolated from each digest. The amino acid sequence was determined by Edman degradation and compared with the deduced amino acid sequence of the CaCB-receptor from rabbit skeletal muscle (Tanabe, T., Takeshima, H., Mikami, A., Flockerzi, V., Takahashi, H., Kangawa, K., Kojima, M., Matsuo, H., Hirose, T., and Numa, S. (1987) Nature 238, 313-318). Phosphoserine was determined as the phenylthiohydantoin-derivative of dithiothreitol-dehydroalanine. The phosphorylated serine was identified as Ser-687 which is localized between the transmembrane regions II and III. A second phosphopeptide was isolated into which phosphate was incorporated into Ser-1617 with a slow time course. This peptide is located in the COOH-terminal cytoplasmic domain of the 165-kDa subunit. It is anticipated that phosphorylation of serine 687 affects the opening probability of the calcium channel.

Animals↗
PubMed1988

Rabbit skeletal muscle microsomes contain two distinct phenylalkylamine-binding sites.

Lu49888, a photoaffinity analog of verapamil, was used to identify specific binding sites for phenylalkylamines of calcium channels present in rabbit skeletal muscle microsomes. Direct binding equilibrium measurements and displacement curves of Lu49888 by its non-radioactive analog yielded an apparent single class of binding sites with Kd and Bmax values of 16.5 nM and 7.5 pmol/mg respectively. Lu49888 was specifically incorporated into three proteins of apparently 165 kDa, and 33 kDa. Incorporation into the 55-kDa protein was blocked by 10--50-fold higher concentrations of unlabeled phenylalkylamines compared to incorporation into the 165-kDa protein, suggesting that the 165-kDa and 55-kDa proteins contain a high and a low-affinity verapamil-binding site respectively. The photoaffinity-labeled proteins were solubilized by 1% digitonin or 1% Chaps in roughly equal amounts. The 165-kDa protein bound to wheat-germ-agglutinin(WGA)--Sepharose and sedimented in sucrose density gradients with the same constant as the purified dihydropyridine receptor, which has been reconstituted to a functional calcium channel. The 55-kDa membrane protein did not bind to the WGA-Sepharose column and sedimented in sucrose density gradients with a lower s value than the 165-kDa protein. The 165-kDa but not the 55-kDa membrane protein was specifically labeled by azidopine, the photoaffinity analogue of dihydropyridines. The 55-kDa protein of the purified dihydropyridine receptor was not significantly labeled by Lu49888 showing that the 55-kDa protein of the membrane is unrelated to the purified high-affinity dihydropyridine receptor.

Affinity Labels↗
PubMed1988

The biochemical properties of L-type calcium channels.

Activation of the cardiac beta-adrenergic receptor stimulates cAMP levels and activates cAMP-dependent protein kinase. The kinase phosphorylates the calcium channel and enhances thereby the availability and the number of channels that are opened during depolarization. The increased calcium influx leads then to a positive inotropic response. The calcium channel can be identified in vitro by organic calcium channel blockers, which bind stereoselectively to a high affinity, low capacity site localized in sarcolemma and junctional sarcoplasmic reticulum. This binding site has been purified from skeletal muscle microsomes. The purified receptor contains three peptides of Mr 165, 55, and 32 kDa in stoichiometric amounts. The high affinity binding sites for dihydropyridines and phenylalkylamines are localized on the 165 kDa peptide. This peptide is phosphorylated up to 2 mol/mol by cAMP-dependent protein kinase. Reconstitution of the purified receptor yields a calcium channel that has many properties of the cardiac L-type calcium channel. It is suggested that these properties are confined to a 165 kDa peptide in skeletal muscle and to a 183 kDa peptide in cardiac muscle.

Animals↗
PubMed1988

Comparison between factor analysis from a phenotypic and genetic correlation matrix using linear type traits of Holstein dairy cows.

Data on 18 linear type scores and production data for 43,428 records by 228 sires were used to compare two different factor-analyses procedures. Using a genetic correlation matrix to obtain a genetic factor matrix showed that the number of derived factors could be reduced to seven genetic factors vs. eight phenotypic factors. Genetic factors provided a good summary of the data and accounted for 79.3% of the total variation vs. 69.1% expressed by eight phenotypic factors. A comparison between the use of a genetic and phenotypic multiple regression analysis showed some difference for the basic rank of factor influence on production and herdlife.

Animals↗
PubMed1988

Phosphorylation of the purified CaCB-receptor.

The purified receptor for calcium channel blockers (CaCB-receptor) from rabbit skeletal muscle contains three polypeptides within a molecular mass of 165, 55, and 32 kDa. cAMP-dependent protein kinase was shown to phosphorylate preferentially the 165-kDa protein. The major phosphorylation site was identified and compared with the recently published primary sequence of the CaCB-receptor. It is concluded that serine 687 is the phosphorylation site. Phosphorylation of serine 687 may regulate the open-state probability of the CaCB-receptor.

Animals↗
PubMed1987

Phosphorylation of the purified receptor for calcium channel blockers by cAMP kinase and protein kinase C.

The dihydropyridine receptor purified from rabbit skeletal muscle contains three proteins of 165, 55 and 32 kDa. cAMP kinase and protein kinase C phosphorylate the 165-kDa and the 55-kDa proteins. At identical concentrations of each protein kinase, cAMP kinase phosphorylates the 165-kDa protein faster than the 55-kDa protein. Protein kinase C phosphorylates preferentially the 55-kDa protein. cAMP kinase incorporates up to 1.6 mol phosphate/mol protein into the 165-kDa protein and 1 mol/mol into the 55-kDa protein upon prolonged incubation. At a physiological concentration of cAMP kinase 1 mol phosphate is incorporated/mol 165-kDa protein within 10 min, suggesting a physiological role of this phosphorylation. Protein kinase C incorporates up to 1 mol phosphate/mol into the 55-kDa protein and less than 1 mol/mol into the 165-kDa protein. Tryptic phosphopeptide analysis reveals that cAMP kinase phosphorylates two distinct peptides in the 165-kDa protein, whereas protein kinase C phosphorylates a single peptide in the 165-kDa protein. cAMP kinase and protein kinase C phosphorylate three and two peptides in the 55-kDa protein, respectively. Mixtures of the tryptic phosphopeptides derived from the 165-kDa and 55-kDa proteins elute according to the composite of the two elution profiles. These results suggest that the 165-kDa protein, which contains the binding sites for each class of calcium channel blockers and the basic calcium-conducting structure, is a specific substrate for cAMP kinase. The 55-kDa protein apparently contains sites preferentially phosphorylated by protein kinase C.

Animals↗
PubMed1987

The 165-kDa peptide of the purified skeletal muscle dihydropyridine receptor contains the known regulatory sites of the calcium channel.

The dihydropyridine receptor purified from rabbit skeletal muscle yields in the presence of dithiothreitol and sodium dodecyl sulfate on polyacrylamide gels bands of apparent molecular mass 165 +/- 5, 130 +/- 5, 55 +/- 3, 32 +/- 2 and 28 +/- 1 kDa (chi +/- SEM, n = 12). Under nonreducing conditions, the 130 kDa and 28-kDa peptides migrate as a single peptide of 165 kDa. These peptides were separated on a HPLC size-exclusion column. The specific absorption coefficients of the isolated peptides were determined. From these a stoichiometry of 1:1.7 +/- 0.2:1.4 +/- 0.3 (chi +/- SEM of 12 experiments with three different preparations) was calculated for the 165-kDa, 55-kDa and 32-kDa peptides. The relative amount of the 130/28-kDa peptide varied with different preparations. Tryptic, chymotryptic and V-8 protease peptides of the isolated proteins suggested that the 130/28-kDa peptide was not related to the 165-kDa peptide. The dihydropyridine photoaffinity analog (+/-)-azidopine was specifically incorporated only into the 165-kDa peptide with an efficiency of about 2.4%. The azido analog of desmethoxyverapamil, LU 49888, was specifically incorporated into the same peptide with an efficiency of 1.5%. These results suggest that only the 165-kDa peptide contains the regulatory sites detected so far in the voltage-operated L-type calcium channel. They suggest further that the 130/28-kDa peptide, which migrates as a 165-kDa peptide under nonreducing conditions, does not contain high-affinity binding sites for the calcium channel blockers.

Affinity Labels↗
PubMed1987

Factor analysis for evaluating relationships between first lactation type scores and production data of Holstein dairy cows.

Data on linear type scores for 18 traits from evaluations from Twenty-First Century Genetics from September 1979 to December 1983 were matched against the DHIA production records. Data for production were 43,428 records by 228 sires, each with at least 20 progeny in at least nine herds. Data were randomly split to analyze and validate the investigation of factor analyses to relate type scores and production. Type scores (1 to 50 points) were adjusted for days in milk and age at first calving. Means of the adjusted type scores ranged from 25.2 to 31.7 (+/- 5.39 to 9.09 SD). A principal component analysis showed that the first eight components accounted for more than 69% of the total variance in type scores. A principal factor analysis followed by a factor rotation was used to define new factors. Multiple linear regression on these factors indicated that herdmate deviation milk and fat are more closely related to characteristics of the mammary system than they are to body traits. For herdlife analyses, using 17,288 records, cows with well-attached udders stayed in herds longer.

Animal Husbandry↗
PubMed1987

Reconstitution of the purified receptor for calcium channel blockers.

The purified receptor for calcium channel blockers from rabbit skeletal muscle was reconstituted into phospholipid vesicles. The reconstitution did not alter the stoichiometry of the peptide chains. [3H]PN 200-110 bound to one site with apparent KD and Bmax values of 9.8 nM and 980 pmol/mg protein, respectively. The binding was stereospecific. D-cis-diltiazem and (-) desmethoxyverapamil affected allosterically the binding of dihydropyridines. This demonstrates the coinsertion of specific binding sites for the three calcium channel blocker into phospholipid vesicles.

Allosteric Regulation↗
PubMed1985

[Increase of alcohol, tobacco and drug consumption by 19-year-old men. A cross-sectional comparison 1971-1978-1982].

The consumption of alcohol, tobacco, hypnotics and pain killers has been compared in three populations of 19-year-old men drawn from the Canton of Zurich in 1971 (6315), 1978 (3802) and 1982 (7341). The percentage of non-consumers in all substances had risen in 1982 above earlier values. The (mean) consumption of tobacco fell from 9.4 g in 1971 to 6.4 g tobacco/day in 1982, though the average cigarette consumption (of the cigarette smokers) only fell from 15.7 to 15.2 cigarettes/day. Alcohol consumption (beer, wine, spirits) decreased slightly from 5.3 glasses/week (mean 1978) to 5.0 glasses/week (mean 1982). These results are compared with investigations in other Swiss populations.

Adult↗
PubMed1983

A rapid procedure for the preparation of highly purified pyruvate decarboxylase from brewer's yeast.

A rapid purification procedure for pyruvate decarboxylase (E.C. 4.1.1.1.) from fresh cells of brewer's yeast (Saccharomyces carlsb.) is reported. The preparation of a crude enzyme (30-45 U/mg) by the use of fractionation steps with protamine sulfate, acetone, and ammonium sulfate takes about 6-7 h. A stable pyruvate decarboxylase (70-85 U/mg) was obtained from such preparations after purification on CM Sephadex C 50 after another 2-3 h. Stability and structural properties are compared for enzymes prepared from fresh and dried yeast.

Carboxy-Lyases↗
PubMed1982

[Conditions of metastatic spread of endometrial cancer: analysis of autopsy findings and clinical data].

Among 263 patients who suffered from endometrial carcinoma and died of their disease or unrelated causes autopsies showed metastases or recurrences in 165 cases. The conditions for metastatic spread were analysed from the morphological parameters of the tumour. The incidence and localization of above all the lymph node metastases are closely correlated to the grading and the depth of invasion (I 0 to I 3/3) of the primary tumour. The incidence of pelvic lymph node metastases is 8.7% at an invasion depth I 1/3,33% at an invasion depth of I 3/3 of the myometrium. Tumours with the invasion depth I 1/3 show metastases in the para-aortic lymph nodes in 17.3% and at the invasion depth I 3/3 in 50% of the cases. At an invasion depth of I 3/3 17% had exclusively para-aortic lymph node metastases. Pelvic lymph node metastases were found in tumours of the grading G 1 in 5.7% of the cases, in grading G3 in 26% of the cases. The tumour grading and primary extent of the endometrial carcinoma area are closely correlated. At a grading G1 90% of the cases were in stage I/II and only 10% in stage III/or IV. At a grading G3 23.8% of the cases were stage I/II and 76.2% of the cases stage III/IV. Based on the presented analysis it is recommended to supplement the conventional treatment at an invasion depth I 2/3 of I 3/3 with radiotherapy of the para-aortic lymph nodes since 27.3 to 50% of these cases show para-aortic metastases. In 17% of the endometrial carcinomas with an invasion depth I 3/3 exclusively para-aortic lymph node metastases were found which do not respond to conventional treatment.

Adult↗