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Biomedical subjects

H Schulz

Publications and source records attributed to H Schulz.

At least 109 records · Page 6Linked to original sources
PubMed1999

Development of the osteoblast phenotype in primary human osteoblasts in culture: comparison with rat calvarial cells in osteoblast differentiation.

In rat osteoblast-like cells, a time-dependent sequence of growth and differentiation-dependent genes has been identified and a model of osteoblast differentiation in culture suggested. We investigated the expression of the bone matrix-associated proteins osteonectin and procollagen I and of the bone cell phenotype-related proteins alkaline phosphatase and osteocalcin during cell culture in primary human osteoblast like cells. Primary human explant cultures from nine young healthy donors were established under highly standardized conditions. Cells in the second passage were analyzed on different days from day 1 to 32, comparing cells growing under the influence of ascorbate with controls. Gene expression was determined by Northern blot analysis or polymerase chain reaction. Osteocalcin expression was also investigated after 1,25-(OH)(2)D(3) stimulation. On the protein level, newly synthesized collagen I, alkaline phosphatase activity, and secretion of osteocalcin were analyzed at all time points. On comparing our findings to the pattern of gene expression suggested for the rat calvarial osteoblast system, we found a similar developmental sequence for the so-called "proliferation" as well as a similar, but lengthened, sequence for the "matrix maturation stage." During "matrix maturation," we found an ongoing proliferation despite increased alkaline phosphatase and decreased procollagen I gene expression. Our study, therefore, shows that in pHOB the gene expression profile proceeded to the "matrix maturation stage," as defined by Owen and colleagues, independent of ongoing proliferation. We were unable to observe the mineralization period as demonstrated by the missing increase of osteocalcin expression and lack of nodule formation in our human osteoblast model. In contrast to the rat system, we found a proliferation stimulating influence of ascorbate, suggesting species-specific differences in response to differentiation factors. From these data, we conclude that general considerations on physiology and pathophysiology of bone cell differentiation have to be confirmed in the human osteoblastic cell system.

Adult↗
PubMed1999

Cytokine-release syndrome in patients with B-cell chronic lymphocytic leukemia and high lymphocyte counts after treatment with an anti-CD20 monoclonal antibody (rituximab, IDEC-C2B8).

Eleven patients with relapsed fludarabine-resistant B-cell chronic lymphocytic leukemia (CLL) or leukemic variants of low-grade B-cell non-Hodgkin's lymphoma (NHL) were treated with the chimeric monoclonal anti-CD20 antibody rituximab (IDEC-C2B8). Peripheral lymphocyte counts at baseline varied from 0.2 to 294.3 x 10(9)/L. During the first rituximab infusion, patients with lymphocyte counts exceeding 50.0 x 10(9)/L experienced a severe cytokine-release syndrome. Ninety minutes after onset of the infusion, serum levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) peaked in all patients. Elevated cytokine levels during treatment were associated with clinical symptoms, including fever, chills, nausea, vomiting, hypotension, and dyspnea. Lymphocyte and platelet counts dropped to 50% to 75% of baseline values within 12 hours after the onset of the infusion. Simultaneously, there was a 5-fold to 10-fold increase of liver enzymes, d-dimers, and lactate dehydrogenase (LDH), as well as a prolongation of the prothrombin time. Frequency and severity of first-dose adverse events were dependent on the number of circulating tumor cells at baseline: patients with lymphocyte counts greater than 50.0 x 10(9)/L experienced significantly more adverse events of National Cancer Institute (NCI) grade III/IV toxicity than patients with less than 50.0 x 10(9)/L peripheral tumor cells (P = .0017). Due to massive side effects in the first patient treated with 375 mg/m(2) in 1 day, a fractionated dosing schedule was used in all subsequent patients with application of 50 mg rituximab on day 1, 150 mg on day 2, and the rest of the 375 mg/m(2) dose on day 3. While the patient with the leukemic variant of the mantle-cell NHL achieved a complete remission (9 months+) after treatment with 4 x 375 mg/m(2) rituximab, efficacy in patients with relapsed fludarabine-resistant B-CLL was poor: 1 partial remission, 7 cases of stable disease, and 1 progressive disease were observed in 9 evaluable patients with CLL. On the basis of these data, different infusion schedules and/or combination regimens with chemotherapeutic drugs to reduce tumor burden before treatment with rituximab will have to be evaluated.

Adult↗
PubMed1999

Experimental analysis of flow calculations based on HRCT imaging of individual bifurcations.

Flow simulations in airways and arteries allow the non-invasive study of transport and deposition processes in these vessel systems. Individual vessel geometries as input for such simulations are highly desirable. Computed tomography (CT) permits the acquisition of binary data to reconstruct such geometries. To prove the suitability of this reconstruction method, we compared measured with simulated velocities within model bifurcations. Particle image velocimetry was applied to measure flow velocities. Numerical simulations of these velocities were carried out by using the CT data of the same models as input to flow calculations (CFD). Within the resolution limits good agreement between measured and simulated velocities was found. For the smallest bifurcation (tube diameter: 2 mm) the agreement was less, indicating a methodical limitation by the actual resolution of the CT-scan technique. The study showed that a combination of CT and CFD can be considered as an appropriate step towards realistic simulations of particle transportation and deposition in individual geometries of the respiratory or cardiovascular systems.

Algorithms↗
PubMed1999

The mouse gene PDCR encodes a peroxisomal delta(2), delta(4)-dienoyl-CoA reductase.

Here we describe the identification and characterization of a novel mouse gene, PDCR, that encodes a peroxisomal Delta(2), Delta(4)-dienoyl-CoA reductase. The mouse PDCR cDNA contains an 892-base pair open reading frame and is predicted to encode a 292-amino acid protein with a deduced molecular mass of 31,298 Da that terminates in a consensus type-1 peroxisomal targeting signal. Purified recombinant PDCR protein was generated from Escherichia coli and catalyzed the NADPH-dependent reduction of Delta(2)-trans, Delta(4)-trans-decadienoyl-CoA with a specific activity of 20 units/mg. Enzymatic characterization followed by high pressure liquid chromatography analysis of the products revealed that PDCR converted Delta(2)-trans,Delta(4)-trans-decadienoyl-CoA to a Delta(3)-enoyl-CoA but not to a Delta(2)-enoyl-CoA. Kinetic analyses demonstrated that PDCR is active on a broad range of Delta(2), Delta(4)-dienoyl-CoAs. Although the observed substrate preference was to Delta(2)-trans,Delta(4)-trans-decadienoyl-CoA, PDCR was also active on a C(22) substrate with multiple unsaturations, a result consistent with the role of peroxisomes in the oxidation of complex, very long chain, polyunsaturated fatty acids. The presence of a type-1 peroxisomal targeting signal Ala-Lys-Leu-COOH at the C terminus of PDCR suggested that this protein may be peroxisomal. We observed that tagged PDCR was efficiently transported to the peroxisome lumen in normal human fibroblasts but not in cells derived from a Zellweger syndrome patient with a specific defect in peroxisomal matrix protein import. We conclude that this protein resides within the peroxisome matrix and therefore represents the first mammalian peroxisomal Delta(2),Delta(4)-dienoyl-CoA reductase to be characterized at the molecular level.

Amino Acid Sequence↗
PubMed1999

Characterization of PECI, a novel monofunctional Delta(3), Delta(2)-enoyl-CoA isomerase of mammalian peroxisomes.

We report here the identification and characterization of human and mouse PECI, a novel gene that encodes a monofunctional peroxisomal Delta(3),Delta(2)-enoyl-CoA isomerase. Human and mouse PECI were identified on the basis of their sequence similarity to Eci1p, a recently characterized peroxisomal Delta(3),Delta(2)-enoyl-CoA isomerase from the yeast Saccharomyces cerevisiae. Cloning and sequencing of the human PECI cDNA revealed the presence of a 1077-base pair open reading frame predicted to encode a 359-amino acid protein with a mass of 39.6 kDa. The corresponding mouse cDNA contains a 1074-base pair open reading frame that encodes a 358-amino acid-long protein with a deduced mass of 39.4 kDa. Northern blot analysis demonstrated human PECI mRNA is expressed in all tissues. A bacterially expressed form of human PECI catalyzed the isomerization of 3-cis-octenoyl-CoA to 2-trans-octenoyl-CoA with a specific activity of 27 units/mg of protein. The human and mouse PECI proteins contain type-1 peroxisomal targeting signals, and human PECI was localized to peroxisomes by both subcellular fractionation and immunofluorescence microscopy techniques. The potential roles for this monofunctional Delta(3),Delta(2)-enoyl-CoA isomerase in peroxisomal metabolism are discussed.

Amino Acid Sequence↗
PubMed1999

Biomonitoring of airborne inorganic and organic pollutants by means of pine tree barks. I. Temporal and spatial variations.

Scots pine (Pinus sylvestris L.) bark samples were collected at two field sites (Neuglobsow, Rösa) and in different years between 1987 and 1996 in the east of Germany. The barks were analyzed with respect to the following inorganic and organic substances: Al, As, B, Ca, Cd, Ce, Cr, Cu, Fe, Hg, Mo, NH4+, Ni, NO3-, PO4(3)-, Pb, Sr, SO4(2)-, Ti, V, W, Zr, Zn, benzo[a]pyrene, fluoranthene, pyrene, alpha-hexachlorocyclohexane (alpha-HCH) and dichlorodiphenyltrichloroethane (DDT). In addition to bark samples from the site Rösa, 53 test sites were investigated in the Nature Park Dübener Heide. Here, the analysis of the barks aimed at discovering spatial patterns of the above-mentioned substances. Since 1991, most of the determined substances (e.g. sulfate, nitrate, calcium, lead, benzo[a]pyrene, alpha-HCH) show decreased concentration values in bark samples from both sites. Temporal variations reflect substantial infra-structural changes in eastern Germany, especially at Rösa and in the industrial region around the cities Leipzig, Halle, and Bitterfeld. Moreover, nitrate concentrations in barks are increasing since 1995. The trend can be explained with increased nitrogen emissions from motor traffic and livestock farms. Spatial patterns of sulphate and ammonia reflect inputs from power plants and agriculture in pine stands of the Nature Park Dübener Heide. The results show that barks of pine trees can be used as biomonitoring tools to indicate and characterize depositions of airborne organic and inorganic pollutants.

Agriculture↗
PubMed1999

Preliminary characterization of Yor180Cp: identification of a novel peroxisomal protein of saccharomyces cerevisiae involved in fatty acid metabolism.

Here we report the preliminary characterization of Yor180Cp, a novel peroxisomal protein involved in fatty acid metabolism in the yeast Saccharomyces cerevisiae. A computer-based screen identified Yor180Cp as a putative peroxisomal protein, and Yor180Cp targeted GFP to peroxisomes in a PEX8-dependent manner. Yor180Cp was also detected by mass spectrometric analysis of an HPLC-separated extract of yeast peroxisomal matrix proteins. YOR180C is upregulated during growth on oleic acid, and deletion of YOR180C from the yeast genome resulted in a mild but significant growth defect on oleic acid, indicating a role for Yor180Cp in fatty acid metabolism. In addition, we observed that yor180cDelta cells fail to efficiently import the enzyme Delta3,Delta2-enoyl-CoA isomerase (Eci1p) to peroxisomes. This result suggested that Yor180Cp might associate with Eci1p in vivo, and a Yor180Cp-Eci1p interaction was detected using the yeast two-hybrid system. Potential roles for Yor180Cp in peroxisomal fatty acid metabolism are discussed.

Amino Acid Sequence↗
PubMed1999

Crystal lattice and phase transitions in Na4TiP2O9 (NTP) and Na4.5FeP2O8(O,F) (NFP) superionic conductors as a function of high pressures and temperatures.

The lattice dynamics of Na(4)TiP(2)O(9) (tetrasodium titanium diphosphorus nonaoxide, NTP) and Na(4.5)FeP(2)O(8)(O,F) (nonasodium diiron tetraphosphorus difluoride octadecaoxide, NFP) crystals, which are superionic conductors with Na(+)-ion conductivity, were studied under high pressures. Lattice constants as a function of hydrostatic pressure were measured on a four-circle diffractometer using a high-pressure cell with diamond anvils. At 1.78 +/- 0.15 GPa NTP undergoes a reversible phase transition from the modulated monoclinic (pseudo-orthorhombic) modification which is stable under atmospheric conditions. A similar phase transition in NTP is observed at 523 K. For NFP, it may be assumed that at least three phase transitions occur when the pressure increases from atmospheric to 12 GPa, at 1.39 +/- 0.08, 4.52 +/- 0.32, and 6.02 +/- 0.02 GPa, as concluded from the change in the unit-cell parameters and in the color of the crystals: the color changes from ginger (dark orange) to pink at ~1.5-2.0 GPa pressure and to violet at ~6.0 GPa.

Journal Article↗
PubMed1999

Heme transfer to the heme chaperone CcmE during cytochrome c maturation requires the CcmC protein, which may function independently of the ABC-transporter CcmAB.

Cytochrome c maturation in Escherichia coli requires the ccm operon, which encodes eight membrane proteins (CcmABCDEFGH). CcmE is a periplasmic heme chaperone that binds heme covalently and transfers it onto apocytochrome c in the presence of CcmF, CcmG, and CcmH. In this work we addressed the functions of the ccmABCD gene products with respect to holo-CcmE formation and the subsequent ligation of heme to apocytochrome c. In the absence of the ccmABCD genes, heme is not bound to CcmE. We report that CcmC is functionally uncoupled from the ABC transporter subunits CcmA and CcmB, because it is the only Ccm protein that is strictly required for heme transfer and attachment to CcmE. Site-directed mutagenesis of conserved histidines inactivates the CcmC protein, which is in agreement with the hypothesis that this protein interacts directly with heme. We also present evidence that questions the role of CcmAB as a heme exporter; yet, the transported substrate remains unknown. CcmD was found to be involved in stabilizing the heme chaperone CcmE in the membrane. We propose a heme-trafficking pathway as part of a substantially revised model for cytochrome c maturation in E. coli.

ATP-Binding Cassette Transporters↗
PubMed1999

Human brain short chain L-3-hydroxyacyl coenzyme A dehydrogenase is a single-domain multifunctional enzyme. Characterization of a novel 17beta-hydroxysteroid dehydrogenase.

Human brain short chain L-3-hydroxyacyl-CoA dehydrogenase (SCHAD) was found to catalyze the oxidation of 17beta-estradiol and dihydroandrosterone as well as alcohols. Mitochondria have been demonstrated to be the proper location of this NAD+-dependent dehydrogenase in cells, although its primary structure is identical to an amyloid beta-peptide binding protein reportedly associated with the endoplasmic reticulum (ERAB). This fatty acid beta-oxidation enzyme was identified as a novel 17beta-hydroxysteroid dehydrogenase responsible for the inactivation of sex steroid hormones. The catalytic rate constant of the purified enzyme was estimated to be 0.66 min-1 with apparent Km values of 43 and 50 microM for 17beta-estradiol and NAD+, respectively. The catalytic efficiency of this enzyme for the oxidation of 17beta-estradiol was comparable with that of peroxisomal 17beta-hydroxysteroid dehydrogenase type 4. As a result, the human SCHAD gene product, a single-domain multifunctional enzyme, appears to function in two different pathways of lipid metabolism. Because the catalytic functions of human brain short chain L-3-hydroxyacyl-CoA dehydrogenase could weaken the protective effects of estrogen and generate aldehydes in neurons, it is proposed that a high concentration of this enzyme in brain is a potential risk factor for Alzheimer's disease.

17-Hydroxysteroid Dehydrogenases↗
PubMed1999

Delta3,5,7,Delta2,4,6-trienoyl-CoA isomerase, a novel enzyme that functions in the beta-oxidation of polyunsaturated fatty acids with conjugated double bonds.

The mitochondrial metabolism of unsaturated fatty acids with conjugated double bonds at odd-numbered positions, e.g. 9-cis, 11-trans-octadecadienoic acid, was investigated. These fatty acids are substrates of beta-oxidation in isolated rat liver mitochondria and hence are expected to yield 5,7-dienoyl-CoA intermediates. 5, 7-Decadienoyl-CoA was used to study the degradation of these intermediates. After introduction of a 2-trans-double bond by acyl-CoA dehydrogenase or acyl-CoA oxidase, the resultant 2,5, 7-decatrienoyl-CoA can either continue its pass through the beta-oxidation cycle or be converted by Delta3,Delta2-enoyl-CoA isomerase to 3,5,7-decatrienoyl-CoA. The latter compound was isomerized by a novel enzyme, named Delta3,5,7,Delta2,4, 6-trienoyl-CoA isomerase, to 2,4,6-decatrienoyl-CoA, which is a substrate of 2,4-dienoyl-CoA reductase (Wang, H.-Y. and Schulz, H. (1989) Biochem. J. 264, 47-52) and hence can be completely degraded via beta-oxidation. Delta3,5,7,Delta2,4,6-Trienoyl-CoA isomerase was purified from pig heart to apparent homogeneity and found to be a component enzyme of Delta3,5,Delta2,4-dienoyl-CoA isomerase. Although the direct beta-oxidation of 2,5,7-decatrienoyl-CoA seems to be the major pathway, the degradation via 2,4,6-trienoyl-CoA makes a significant contribution to the total beta-oxidation of this intermediate.

Acyl Coenzyme A↗
PubMed1999

Evaluation of a putative major susceptibility locus for juvenile myoclonic epilepsy on chromosome 15q14.

Juvenile myoclonic epilepsy (JME) is a genetically determined common subtype of idiopathic generalized epilepsy (IGE). Significant evidence for linkage has been reported for a susceptibility locus for JME in the chromosomal region 15q14 that harbors the gene encoding the alpha7 subunit of the neuronal nicotinic acetylcholine receptor (CHRNA7). The present study was designed to test the earlier linkage finding and to explore whether this susceptibility locus is involved in the epileptogenesis of a broader spectrum of IGE syndromes. Multipoint parametric and nonparametric linkage analyses with seven microsatellite polymorphisms encompassing the region of the CHRNA7 gene were performed using two diagnostic schemes of JME-related traits in two groups of multiplex families ascertained through probands with either JME (n = 27) or idiopathic absence epilepsy (n = 30). The present linkage study failed to replicate evidence for a major susceptibility locus for JME in the region encompassing the CHRNA7 gene. In addition, we found no hint in favor of linkage to 15q14 under the broad diagnostic scheme in any of the sets of families. If genetic variation in this region confers susceptibility to JME, then its effect size might be too small or its occurrence too rare to be detected in the investigated families.

Adolescent↗
PubMed1999

1,25 dihydroxyvitamin-D3 attenuates the confluence-dependent differences in the osteoblast characteristic proteins alkaline phosphatase, procollagen I peptide, and osteocalcin.

In the present study a cell culture model of primary human osteoblasts based on degrees of confluence was investigated by measuring basal and 1,25(OH)2D3stimulated levels of the osteoblast characteristic proteins alkaline phosphatase (AP), procollagen I-peptide (PICP), and osteocalcin (OC), as well as the corresponding gene expression. Primary osteoblast-like cell cultures from seven donors were treated in the second passage with 1,25(OH)2D3 (5 x 10(-8) M for 48 hours) and investigated at four stages of confluence (stage I 50%, stage II 75%, stage III 100%, and stage IV 7 days postconfluence). In untreated cultures passing through the different stages of confluence, we saw a 1.8-fold increase of AP activity, a 2. 3-fold increase of OC secretion, but a decrease of PICP levels to 0. 36-fold. Gene expression showed only minor variation between the different confluence stages. 1,25(OH)2D3 did not significantly affect PICP production. Alkaline phosphatase protein was stimulated during proliferation until confluence, with no effect thereafter. Surprisingly, OC secretion and mRNA expression were stimulated in all four stages to the same absolute level independent of basal values. We conclude that our results correspond to other studies showing differentiation-stage dependent changes of basal levels of osteoblast-specific proteins. However, 1,25(OH)2D3 stimulation decreased the confluence-dependent difference for AP and abolished it for osteocalcin, thus leading to a more differentiated phenotype of the osteoblast. Therefore, 1,25(OH)2D3 stimulation might improve the reproducibility of results obtained at different confluence stages from cultures of clinical samples.

Alkaline Phosphatase↗
PubMed1999

[Skull and mandible. On Joseph Beuys' "ancient sled." Medical art history observation].

Few people are aware that Joseph Beuys (1921-1986), one of the most important artists at the end of the twentieth century, studied various aspects of the human skull. Beuys used teeth (especially molars), antlers, and horns as organically differentiated formations of solid substances of the viscerocranium, associating them in a very visual way with the "streaming circulation" principle. In addition, in his early drawings, in particular, Beuys replaced the lower jaw with a sledge. The artist has thus created interesting and strange constructions concerned with the structure of the jaw and the craniovertebral transition. Certain characteristic structural elements of sledges show a remarkable formal analogy to the ramus of mandible. The base of the body of mandible becomes a sliding surface, the iron runners of the sledge. Replacing the lower jaw with a sledge raises questions concerning movement and the effect of energy on the skull and on the earth. The artist's understanding of anatomy goes for beyond than that of normal medicine. It is formed by his thinking, his energy plan, and by his own theory of metamorphosis. With his skull and Urschlitten motif, Beuys makes us aware of the transitory layers of consciousness between life and death. "Head" and "sledge" are early forms of sculptural thinking in the work of Joseph Beuys.

Germany↗
PubMed1999

[Correlation between epiluminescence microscopy characteristics of malignant melanomas and Clark's level of invasion].

Many epiluminescence microscopy (ELM) characteristics of malignant melanoma support the differential diagnosis of pigmented skin tumors. A preinvasive evaluation of level of invasion would be valuable for planning the excision margins. Since sonography for tumor thickness measurement is rarely available in a practice we searched for specific ELM criteria correlating with Clark's level of invasion. In our retrospective study of 120 malignant melanomas of 30 ELM features were studied for their correlation and the association was significant for 15 features.The following criteria were found only in level III-IV melanomas: intralesional horizontally elongated blood vessels, spontaneous microhemorrhages, plaster-of-Paris-like lacunae, grey-blue/yellowish-brown/reddish saccular pattern and eccentric nodes (reddish, livid, blue). 7 characteristics were predominantly found in level III-IV melanomas and seldom in "thin" melanomas (level I-II): deeply localized gray-blue/-brown fragmentary network, whitish-opaque septa, whitish- or bluish-opaque veil, negative pigmented network, areola with evenly arranged capillaries, polymorphic capillaries. Perivascular melanophages, eccentric dark blotches, pseudotrabeculae of melanophages and greyish-blue annular perifollicular pigmentations were the most significant association of ELM criteria in "thin" melanomas (level I-II). Epiluminescence microscopy is not only a tool for the differentiation of melanocytic lesions but also for a preinvasive evaluation of Clark's level of invasion.

Adult↗
PubMed1999

The PBX-regulating protein PREP1 is present in different PBX-complexed forms in mouse.

Human PREP1, a novel homeodomain protein of the TALE super-family, forms a stable DNA-binding complex with PBX proteins in solution, a ternary complex with PBX and HOXB1 on DNA, and is able to act as a co-activator in the transcription of PBX-HOXB1 activated promoters (Berthelsen, J., Zappavigna, V., Ferretti, E., Mavilio, F., Blasi, F. , 1998b. The novel homeoprotein Prep1 modulates Pbx-Hox protein cooperatity. EMBO J. 17, 1434-1445; Berthelsen, J., Zappavigna, V., Mavilio, F., Blasi, F., 1998c. Prep1, a novel functional partner of Pbx proteins. EMBO J. 17, 1423-1433). Here we demonstrate the presence of DNA-binding PREP1-PBX complexes also in murine cells. In vivo, PREP1 is a predominant partner of PBX proteins in various murine tissues. However, the choice of PBX family member associated with PREP1 is largely tissue-type specific. We report the cloning and expression domain of murine Prep1 gene. Murine PREP1 shares 100% identity with human PREP1 in the homeodomain and 95% similarity throughout the whole protein. In the adult mouse, PREP1 is expressed ubiquitously, with peaks in testis and thymus. We further demonstrate the presence of murine Prep1 mRNA and protein, and of different DNA-binding PREP1-PBX complexes, in mouse embryos from at least 9.5 days p.c. Moreover, we show that PREP1 is present in all embryonic tissues from at least 7.5-17.5 days p.c with a predominantly nuclear staining. PREP1 is able to super-activate the PBX-HOXB-1 autoregulated Hoxb-1 promoter, and we show that all three proteins, PREP1, PBX and HOXB-1, are present together in the mouse rhombomere 4 domain in vivo, compatible with a role of PREP1 as a regulator of PBX and HOXB-1 proteins activity during development.

3T3 Cells↗