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Biomedical subjects

A Schulz

Publications and source records attributed to A Schulz.

At least 37 records · Page 2Linked to original sources
PubMed2003

Elimination costs for different wastewater compounds.

The present report presents the system and discusses the results of the cost calculation for the reduction/elimination of different wastewater and sludge compounds. These costs were calculated for different types of processes at 102 wastewater treatment plants of Emschergenossenschaft/Lippeverband and Aggerverband. Comparing enhanced biological phosphorus removal and precipitation, one of the results indicates that in general the costs for elimination of one kilogram of phosphorus are lower in the plants in which only chemical precipitation is used for P reduction. Further results of the cost calculation will be presented with a discussion of their possible influence on planning decisions.

Benchmarking↗
PubMed2002

[Fibrous dysplasia: differential diagnosis from Paget's disease].

HISTORY AND CLINICAL FINDINGS: A 27-year-old woman presented with chronic diffuse bone pain and skeletal deformities. Since the age of 3 years she had occipital hyperostosis. Since aged 13 years she had symptoms indicating spinal root involvement due to hyperkyphosis. For the last 6 years there was evidence of destructive and hyperplastic changes in the region of the middle ribs. Alkaline phosphatase (APL) had been elevated (> 250 U/l) for several years. Three years before the present admission the patient had been hospitalized elsewhere because of bone pain and had received intermittent infusions of pamindronate to a total of 600 mg. INVESTIGATIONS: Laboratory tests showed moderate rise in bone-specific APL and osteocalcin. Conventional x-ray examinations and computed tomography showed lesions in the occipital bone, sella turcica and ethmoid air cells. Several thoracic vertebral fractures were demonstrated. Skeletal scintigraphy indicated enrichment in the occipital and supraorbital regions, as well as in vertebrae and ribs. Dual energy x-ray absorptiometry (DEXA) showed osteopenia. Bone biopsy from the occipital lesion revealed fibrous dysplasia. TREATMENT AND COURSE: The diagnosis of fibrous dysplasia having been confirmed, cyclical treatment with i.v. pamidronate was given for 6 months. It was well tolerated and lessened the pain without changing the objective findings. CONCLUSION: In case of uncertain radiological and scintigraphic findings in the differential diagnosis of fibrous dysplasia, Paget's disease or bone tumor, it is essential to obtain a biopsy and, if available, perform gene analysis.

Absorptiometry, Photon↗
PubMed2002

Chemical synthesis of beta-defensins and LEAP-1/hepcidin.

A large and steadily growing subfamily of antimicrobially active peptides of animals and plants is formed by the defensins, which are highly disulfide-bonded, cationic peptides with a molecular mass of about 4 kDa. The synthesis of the human beta-defensins 1 and 2 (hBD-1, hBD-2) as well as of the novel murine beta-defensins 7 and 8 (mBD-7 and mBD-8) is reported. The peptides were synthesized by solid-phase peptide synthesis using fluorenylmethoxycarbonyl chemistry. The linear products were oxidized in the presence of the cysteine/cystine redox system to the biologically active molecules. The correct disulfide connectivity of the resulting cyclic products was partly verified by mass spectrometry and sequence analysis of the fragments obtained after tryptic cleavage. In addition, the recently discovered antimicrobially active human peptide LEAP-1/hepcidin, which contains four disulfide bonds, was successfully synthesized and subsequently oxidized. For Liver-expressed anti microbial peptide (LEAP)-1/hepcidin and hBD-1, the identity of native and synthetic peptides was demonstrated by high-pressure liquid chromatography and capillary electrophoretic analysis. The general synthetic procedure is suitable to rapidly perform the total chemical synthesis of novel fully bioactive defensins, which are expected to be identified soon, as well as of structurally modified analogs.

Amino Acid Sequence↗
PubMed2002

High-dose chemotherapy with autologous stem cell rescue in children with nephroblastoma.

Children with Wilms tumor who have a particular risk of failure at relapse or at primary diagnosis were treated with high-dose chemotherapy (HDC) and autologous peripheral blood stem cell rescue in order to improve their probability of survival. From April 1992 to December 1998, 23 evaluable patients received HDC within the German Cooperative Wilms Tumor Studies. Nineteen were given melphalan, etoposide and carboplatin (MEC); the others received different regimens. The dose of carboplatin was adjusted according to renal function. Indications for HDC were high-risk relapse in 20 patients, bone metastases in two patients and no response in one patient. Fourteen of 23 patients are alive after a median observation time of 41 months, 11 of 14 in continuous complete remission, three in CR after relapse post HDC. The estimated survival and event-free survival for these patients are 60.9% and 48.2%. Twelve children relapsed after HDC; nine of them died within 12 months and three are surviving from 20 to 33 months after relapse. The main toxicities were hematologic, mucositis and renal (tubular dysfunction; intermittent hemodialysis in one patient). There were no toxic deaths. About half of the children suffering from Wilms tumor with very unfavorable prognostic factors survive disease-free after HDC for over 3 years. Besides hematological toxicity, mucositis and infections, renal function is at risk during HDC. With dose adjustment on glomerular filtration rate, however, no permanent renal failure was observed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

[Kurt Goldstein's understanding of amnesic aphasia and its underlying disorder - an early model of the pensée opératoire of the French psychosomatic school?].

Kurt Goldstein's understanding of amnesic aphasia in some regards anticipated the model of the pensée opératoire, a concept developed during the 60's and 70's by the French psychoanalytical school of psychosomatics. Goldstein interpreted amnesic aphasia within the framework of a "basic disorder". Closely following the philosopher Ernst Cassirer, Goldstein described amnesic aphasia as an expression of a general alteration following localized or generalised brain damage. Due to various historical events (world war, fascism, the holocaust) as well as developments during the 20(th) century (dominance of the English language in many areas of science), these connections were forgotten or were no longer recognised as such. Without wanting to determine the extent to which the concept of pensée opératoire possesses validity, one can interpret Goldstein's reflections on aphasia as a heretofore unreceived preliminary model of the psychosomatic concept of the French School.

Anomia↗
PubMed2001

[Me3SiN(PPh3)-ICN]: a new labile donor-acceptor complex.

The reaction behavior of trimethylsilyl phosphanimine, Me3SiNPPh3, toward the pseudohalogen species XCN (X = Cl, Br, and I), especially the intermediate formation of [Me3SiN(PPh3)-XCN] adduct complexes, was investigated in solution. Only the ICN adduct was shown to be metastable in solution, with respect to further reaction into Ph3PNCN and Me3SiX, and can be intercepted. Raman and X-ray data of the ICN adduct revealed a very labile donor-acceptor complex with the iodine atom of the ICN moiety loosely bound to the nitrogen atom of Me3SiNPPh3. There are two distinct rather long N...I bonds with bond lengths of 2.634(1) and 2.739(14) A. The structure and bonding are discussed on the basis of natural bond orbital analysis and valence bond considerations.

Journal Article↗
PubMed2001

A theoretical and experimental study on the Lewis acid-base adducts (P(4)E(3)).(BX(3)) (E = S, Se; X = Br, I) and (P(4)Se(3)).(NbCl(5)).

The Lewis acid-base adducts (P(4)E(3)).(BX(3)) (E = S, Se; X = Br, I) and (P(4)Se(3)).(NbCl(5)) have been prepared and characterized by Raman, IR, and solid-state (31)P MAS NMR spectroscopy. Hybrid density functional calculations (B3LYP) have been carried out for both the apical and the basal (P(4)E(3)).(BX(3)) (E = S, Se; X = Br, I) adducts. The thermodynamics of all considered species has been discussed. In accordance with solid-state (31)P MAS NMR and vibrational data, the X-ray powder diffraction structures of (P(4)S(3)).(BBr(3)) [monoclinic, space group P2(1)/m (No. 11), a = 8.8854(1) A, b = 10.6164(2) A, c = 6.3682(1) A, beta = 108.912(1) degrees, V = 568.29(2) A(3), Z = 2] and (P(4)S(3)).(BI(3)) [orthorhombic, space group Pnma (No. 62), a = 12.5039(5) A, b = 11.3388(5) A, c = 8.9298(4) A, V = 1266.09(9) A(3), Z = 4] indicate the formation of an apical P(4)S(3) complex in the reaction of P(4)S(3) with BX(3) (X = Br, I). Basal adducts are formed when P(4)Se(3) is used as the donor species. Vibrational assignment for the normal modes of these adducts has been made on the basis of comparison between theoretically obtained and experimentally observed vibrational data.

Journal Article↗
PubMed2001

Structural variations and bonding in gold halides: a quantum chemical study of monomeric and dimeric gold monohalide and gold trihalide molecules, AuX, Au2X2, AuX3, and Au2X6 (X = F, Cl, Br, I).

The molecular structures of all gold mono- and trihalides and of their dimers have been calculated at the B3LYP, MP2, and CCSD(T) levels of theory by using relativistic pseudopotentials for all atoms except fluorine. Our computations support the experimental observation that the relative stability of the monohalides increases from the fluoride toward the iodide, while the stability trend of the trihalides is the opposite. The potential energy surface (PES) of all gold trihalides has been investigated. These molecules are typical Jahn-Teller systems; the trigonal planar D3h-symmetry geometry does not correspond to the minimum energy structure for any of them. At the same time, the amount and character of their Jahn-Teller distortion changes gradually from AuF3 to AuI3. The minimum energy geometry is a T-shaped structure for AuF3 and AuCl3, with a Y-shaped transition-state structure. For AuI3, the Y-shaped structure lies lower than the T-shaped structure on the PES. For AuBr3 and AuI3, neither of them is the global minimum but instead an L-shaped structure, which lies outside the Jahn-Teller PES. This structure can be considered to be a donor-acceptor system, or a closed-shell interaction, with I2 acting as donor and AuI as acceptor. The dimers of gold monohalides have very short gold-gold distances and demonstrate the aurophilic interaction. The dimers of the trihalides are planar molecules with two bridging halogen atoms.

Journal Article↗
PubMed2001

Self-assembled organometallic [12]metallacrown-3 complexes.

The reaction of [(arene)RuCl2]2 (arene = C6H6, cymene, C6H3Et3, or C6Me6) or [Cp*RhCl2]2 with 3-hydroxy-2-pyridone in the presence of Cs2CO3 gives trinuclear metallamacrocyclic complexes. The self-assembly process was shown to be completely diastereoselective, and a racemic mixture of complexes with M(R)M(R)M(R) or MsMsMs (M=Ru, Rh) configuration was obtained. Plausible mononuclear intermediates of the formula [(arene)RuCl(C5H4NO2)] (arene = cymene, C6Me6) have been isolated and characterized. A structurally related trimer was synthesized by using [(cymene)RuCl2]2 and 3-acetamido-2-pyridone instead of 3-hydroxy-2-pyridone. The macrocycles were shown to be highly potent ionophores for Na+ and/or Li+ with negligible affinities for the larger cation K+. The selectivities of the receptors depend on the pi-ligand present: whereas the (C6H6)Ru- and (cymene)Ru complexes bind both Li+ and Na+, the (C6Me6)Ru-, (C6H3Et3)Ru-, and Cp*Rh complexes bind exclusively Li+. For all receptors, the presence of alkali metal ions can be detected electrochemically: the peak potential is shifted by > 300 mV toward anionic potential upon binding. This behavior was utilized to detect Li+ and Na+ colorimetrically. Single crystal X-ray analyses have been carried out on eight complexes, four of which are bound to an alkali metal halide ion pair. Structural parameters, which affect the affinity and selectivity are discussed. A computational study on [[MX][12]crown-3] complexes (M =Li, Na; X=Cl, Br, I) was performed in order to compare relevant bond lengths and angles of the energy-minimized structures with those of the organometallic receptors.

Journal Article↗
PubMed2001

[Thrombotic-thrombocytopenic purpura (Moschcowitz syndrome)].

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP), in 1924 first described by Moschcowitz, is a clinically heterogeneous syndrome associated with thrombocytopenia, Coombs-negative hemolytic anemia, neurologic changes, renal impairment, and fever. TTP is found after various bacterial or viral infectious diseases, autoimmune diseases and also in association with different drugs. PATHOGENESIS: After initial endothelial cell injury unusually large von Willebrand factors (vWF) are found in plasma of patients with thrombotic thrombocytopenic purpura. Because of impaired proteolysis these large forms lead to thrombosis of the small vessels. The microangiopathy is followed by mechanical destruction of red cells. In peripheral blood smears these fragmentocytes are important for diagnosis and clinical course. THERAPY: The therapy of choice is plasma exchange against fresh frozen plasma, whereupon the mortality could be dramatically reduced in the past decades. In case of treatment resistance to plasma exchange there exists no common treatment schedule. One therapy option is immunosuppressive treatment with corticosteroids and vincristine. In case of chronic relapsing TTP splenectomy should be discussed. In spite of severe thrombocytopenia substitution of thrombocytes is contraindicated.

Diagnosis, Differential↗
PubMed2001

Single molecule DNA sequencing in submicrometer channels: state of the art and future prospects.

We demonstrate a new method for single molecule DNA sequencing which is based upon detection and identification of single fluorescently labeled mononucleotide molecules degraded from DNA-strands in a cone shaped microcapillary with an inner diameter of 0.5 microm. The DNA was attached at an optical fiber via streptavidin/biotin binding and placed approximately 50 microm in front of the detection area inside of the microcapillary. The 5'-biotinylated 218-mer model DNA sequence used in the experiments contained 6 fluorescently labeled cytosine and uridine residues, respectively, at well defined positions. The negatively charged mononucleotide molecules were released by addition of exonuclease I and moved towards the detection area by electrokinetic forces. Adsorption of mononucleotide molecules onto the capillary walls as well as the electroosmotic (EOF) flow was prevented by the use of a 3% polyvinyl pyrrolidone (PVP) matrix containing 0.1% Tween 20. For efficient excitation of the labeled mononucleotide molecules a short-pulse diode laser emitting at 638 nm with a repetition rate of 57 MHz was applied. We report on experiments where single-stranded model DNA molecules each containing 6 fluorescently labeled dCTP and dUTP residues were attached at the tip of a fiber, transferred into the microcapillary and degraded by addition of exonuclease I solution. In one experiment, the exonucleolytic cleavage of 5-6 model DNA molecules was observed. 86 photon bursts were detected (43 Cy5-dCMP and 43 MR121-dUMP) during 400 s and identified due to the characteristic fluorescence decay time of the labels of 1.43+/-0.19 ns (Cy5-dCMP), and 2.35+/-0.29 ns (MR121-dUMP). The cleavage rate of exonuclease I on single-stranded labeled DNA molecules was determined to 3-24 Hz under the applied experimental conditions. In addition, the observed burst count rate (signals/s) indicates nonprocessive behavior of exonuclease I on single-stranded labeled DNA.

Base Sequence↗
PubMed2001

Reaction of 2,4,6-triazido-1,3,5-triazine with triphenylphosphane. syntheses and characterization of the novel 2-triphenylphosphanimino-4-azidotetrazolo[5,1-a]-[1,3,5]triazine and 2,4,6,-tris(triphenylphosphanimino)-1,3,5-triazine.

2-Triphenylphosphanimino-4-azidotetrazolo[5,1-a]-[1,3,5]triazine (6) was obtained by reaction of 2,4,6-triazido-1,3,5-triazine (1) with 1 equiv of triphenylphosphane. Raman and X-ray data revealed that only one azide group formed a tetrazole ring system whereas the second azide group did not undergo ring closure. To investigate the equilibrium between the tetrazole isomer and the open-chain azide structure for these and related species, (31)P NMR studies were carried out. The obtained spectra displayed an equilibrium between the tetrazole and the open-chain azide isomers. 2,4,6-Tris(triphenylphosphanimino)-1,3,5-triazine (4) was prepared by treatment of 1 with 3 equiv of triphenylphosphane, and its X-ray structure is discussed. On the basis of PM3 semiempirical and density functional calculations, the reaction of 1 with triphenylphosphane was studied. The thermodynamics of different isomerization reactions and the activation barriers to cyclization were estimated.

Journal Article↗
PubMed2001

Loss of the ClC-7 chloride channel leads to osteopetrosis in mice and man.

Chloride channels play important roles in the plasma membrane and in intracellular organelles. Mice deficient for the ubiquitously expressed ClC-7 Cl(-) channel show severe osteopetrosis and retinal degeneration. Although osteoclasts are present in normal numbers, they fail to resorb bone because they cannot acidify the extracellular resorption lacuna. ClC-7 resides in late endosomal and lysosomal compartments. In osteoclasts, it is highly expressed in the ruffled membrane, formed by the fusion of H(+)-ATPase-containing vesicles, that secretes protons into the lacuna. We also identified CLCN7 mutations in a patient with human infantile malignant osteopetrosis. We conclude that ClC-7 provides the chloride conductance required for an efficient proton pumping by the H(+)-ATPase of the osteoclast ruffled membrane.

Adenosine Triphosphatases↗
PubMed2001

News on the Maillard reaction of oligomeric carbohydrates: a survey.

The reaction behaviour of monosaccharides in the Maillard reaction is well investigated. Amadori compounds, for instance, form deoxyhexosuloses which are responsible for the formation of volatile flavour substances and melanoidins. These intermediates can be quantified by a trapping reaction with o-phenylendiamine as stable quinoxalines. However the reaction behaviour of oligo and polymeric carbohydrates in non-enzymatic browning reactions are hardly known. Therefore maltooligosaccharides and in some cases starch were used together with glycine as model substances to investigate the Maillard reaction mechanism of oligo and polysaccharides. In quasi waterfree reaction systems oligosaccharides form alpha-dicarbonyl compounds via a "peeling off" mechanism. The Maillard reaction with the amino compound starts at the reducing end of an alpha-glucane residue and results in the formation of 1,4-dideoxyhexosulose. This is the main alpha-dicarbonyl compound found by trapping reaction with o-phenylendiamine during thermally induced degradation of maltooligosaccharides. The thermal reaction of maltooligosaccharides is accompanied by transglycosylations leading to formation of branched carbohydrate structures and by dehydrations forming anhydrosugars. The reaction mechanism which is responsible for degradation of oligomeric carbohydrates in aqueous model systems differs significantly from pathways mentioned above for water free reaction conditions. As the main alpha-dicarbonyl compound 3-deoxypentosulose is formed which can be proved also by trapping reactions. Under aqueous reaction conditions the formation of other alpha-dicarbonyls plays only a marginal role in the Maillard reaction of oligomeric carbohydrates. In an aqueous system transglycosylation and dehydration of maltooligosaccharides are not important.

Hot Temperature↗
PubMed2001

Accurate disulfide formation in Escherichia coli: overexpression and characterization of the first domain (HF6478) of the multiple Kazal-type inhibitor LEKTI.

The human hemofiltrate peptide HF6478, a putative serine proteinase inhibitor, which is part of the precursor protein LEKTI, was cloned, overexpressed, and purified. HF6478 contains two disulfide bridges with 1-4, 2-3 connectivity, sharing partial homology to Kazal-type domains and other serine proteinase inhibitors. It was expressed as thioredoxin (Trx) fusion protein, and disulfide formation occurred in the oxidative cytoplasm of Escherichia coli Origami (DE3) strain which carries a trxB(-)/gor522(-) double mutation. The soluble fusion protein was purified using metal-chelating affinity chromatography. Cleavage of the Trx fusion protein with factor Xa and subsequent purification yielded the final product in amounts sufficient for structural studies. Characterization of recombinant HF6478 was done by amino acid sequencing, mass spectrometry, capillary zone electrophoresis, and CD spectroscopy. Taking the blood filtrate peptide HF6478 as example, we present a strategy which should facilitate the expression of different extracellular proteins in the E. coli cytoplasm.

Carrier Proteins↗
PubMed2001

[Cellular senescence: a mechanism of the development of osteoporosis?].

Osteoporosis is one of the most common diseases of the elderly. This leads to the hypothesis that the ageing of the organism is reflected as a cytogerontological effect in a specific loss of bone cell function. Three underlying pathogenetic mechanisms need to be considered: (1) cellular aging in general, (2) impairment of the systemic stimulation of bone formation by e.g. decreasing hormone levels, and (3) lower cellular effectiveness of cytokines and growth factors. Cellular aging consists of replicative and postmitotic senescence. While the replicative senescence limits only the number of cell cycles, the postmitotic aging is influenced by endo- and exogenous factors. These lead to genetic alterations known as delayed persistent genomic instability and to an increasing impairment of specific cellular functions. In the postmitotic phase, osteopenia caused by the decrease of systemically available sexual hormones is a major field of research. Osteopenia caused by a decreased activity of locally effective cytokines and growth factors is becoming increasingly understood. New therapeutic strategies, which modulate the local osteoblast activity, e.g. in bone defect healing, are under development. In conclusion, cellular senescence is considered to be one element in the development of bone loss. Potential therapeutic targets may open up an additional path in the treatment of local and systemic osteopenias.

Adult↗