Search PubMed⌕ Search

Biomedical subjects

J Schütz

Publications and source records attributed to J Schütz.

At least 19 recordsLinked to original sources
PubMed2001

Isolation and spectroscopic characterization of the structural subunits of keyhole limpet hemocyanin.

Keyhole limpet hemocyanin is a respiratory glycoprotein of high molecular weight from the gastropod mollusc Megathura crenulata. Two subunits, KLH1 and KLH2, were isolated using ion exchange chromatography and their physical properties are compared with the parent molecule. The various proteins are characterized by fluorescence spectroscopy, combined with fluorescence quenching studies, using acrylamide, cesium chloride and potassium iodide as tryptophan quenchers. The conformational stability of the native aggregate and its isolated structural subunits are also studied by circular dichroism and fluorescence spectroscopy as a function of temperature, as well as in the presence of guanidinium hydrochloride and urea. The associated subunits in the hemocyanin aggregates increase considerably the melting temperature to 67 degrees C and the free energy of stabilization in water, DeltaG(H(2)O)(D), towards guanidinium hydrochloride is higher for the decamer as compared to the isolated subunits; this difference can be accounted for by the stabilizing effects of intra-subunit interactions exerted within the oligomer. The copper-dioxygen complex at the active site additionally stabilizes the molecule, and removing of the copper ions increases the tryptophan emission and the quantum yield of the fluorescence.

Animals↗
PubMed1999

Primary structure and unusual carbohydrate moiety of functional unit 2-c of keyhole limpet hemocyanin (KLH).

The complete amino acid sequence of the Megathura crenulata hemocyanin functional unit KLH2-c was determined by direct sequencing and matrix-assisted laser desorption ionization mass spectrometry of the protein, and of peptides obtained by cleavage with EndoLysC proteinase, chymotrypsin and cyanogen bromide. This is the first complete primary structure of a functional unit c from a gastropod hemocyanin. KLH2-c consists of 420 amino acid residues. Circular dichroism spectra indicated approx. 31% beta-sheet and 29% alpha-helix contents. A multiple sequence alignment with other molluscan hemocyanin functional units revealed average identities between 41 and 49%, but 55% in case of Octopus hemocyanin functional unit c which is the structural equivalent to KLH2-c. KLH2-c has a molecular mass of approx. 48 kDa as calculated from its sequence and a measured mass of approx. 56 kDa; the mass difference is attributed to the sugar side chains usually decorating molluscan hemocyanin. However, inspection of the sequence of KLH2-c revealed no potential N-linked carbohydrate attachment sites, and this was supported by its inability to bind concanavalin A. Also KLH1-c was unreactive, whereas most, if not all, other functional units of KLH1 and KLH2 reacted positively to this lectin. On the other hand, peanut agglutinin specifically binds KLH2-c, indicating the presence of O-glycosidically linked carbohydrates in this functional unit. This contrasts to all other KLH functional units (including KLH1-c), which lack O-linked glycosides. The present results are discussed in view of the recent X-ray structure of the functional unit g from Octopus hemocyanin, and a published record of the Thomsen Friedenreich tumor antigenic epitope in KLH.

Amino Acid Sequence↗
PubMed1999

Sea snake Hydrophis cyanocinctus venom. I. Purification, characterization and N-terminal sequence of two phospholipases A2.

Two phospholipases A2 (PLA2, H1 and H2) from sea snake Hydrophis cyanocinctus venom were purified to homogeneity in a single step using reversed-phase high performance liquid chromatography on a Nucleosil 7C18 column. The molecular weights of H1 and H2, as estimated by MALDI MS, were 13588.1 and 13247.2 Da, respectively. The N-terminal 60 amino acid residues were determined by direct automated Edman degradation analysis. Since both PLA2s show close sequence homologies to those of PLA2s from other Elapid snakes (60-84%) they have been tentatively classified as belonging to group-IA and Asp-49 phospholipases A2. Despite the sequence variation (18%) between H1 and H2, their general structural organization is very similar as shown by their clearly related CD spectra. Furthermore, both enzymes are quite thermostable (60-65 degrees C) as determined by temperature variable CD spectra, indicating that the enzymes contain compact folded structure, mainly based on the core structure of disulfide bridges. However, the major PLA2 (H1) shows higher toxicity to albino rats (LD50 i.p. 0.04 mg/kg) and purification resulted in 18-fold increase in toxicity over the crude or whole venom (LD50 i.p. 0.80 mg/kg). H1 also shows edema-inducing and indirect haemolytic but no haemorrhagic activity. Unlike the toxic PLA2-H1, enzyme H2 was not toxic to albino rats but showed edema-inducing and indirect haemolytic activities.

Amino Acid Sequence↗
PubMed1998

Capillary electrophoresis in biochemical and clinical laboratoriesp selected attractive examples.

As demonstrated by selected examples from our laboratories, CE is a unique methodology for purity control of synthetic as well as natural tissue-isolated biopolymers, a prerequisite before reliable biotestings should be performed. A combination of rapid matrix-assisted laser desorption ionization mass and CE electrophoretic mobility determinations facilitates primary sequence determinations of enzymatic peptide digest mixtures often making costly Edman degradations unnecessary. The enormous separation efficiency and large variety of different possible separation modes in CE, allow detection of single components in complex mixtures which is demonstrated by the apolipoprotein A-I determination in human blood serum in this communication.

Algorithms↗
PubMed1998

Purification and primary structure of low molecular mass peptides from scorpion (Buthus sindicus) venom.

The primary structures of four low molecular mass peptides (Bs 6, 8, 10 and 14) from scorpion Buthus sindicus were elucidated via combination of Edman degradation and matrix-assisted laser desorption ionization mass spectrometry. Bs 8 and 14 are cysteine-rich, thermostable peptides composed of 35-36 residues with molecular weights of 3.7 and 3.4 kDa, respectively. These peptides show close sequence homologies (55-78%) with other scorpion chlorotoxin-like short-chain neurotoxins (SCNs) containing four intramolecular disulfide bridges. Despite the sequence variation between these two peptides (37% heterogeneity) their general structural organization is very similar as shown by their clearly related circular dichroism spectra. Furthermore, Bs6 is a minor component, composed of 38 residues (4.1 kDa) containing six half-cystine residues and having close sequence identities (40-80%) with charybdotoxin-like SCNs containing three disulfide bridges. The non-cysteinic, bacic and thermolabile Bs10 is composed of 34 amino acid residues (3.7 kDa), and belongs to a new class of peptides, with no sequence resemblance to any other so far reported sequence isolated from scorpions. Surprisingly, Bs10 shows some limited sequence analogy with oocyte zinc finger proteins. Results of these studies are discussed with respect to their structural similarities within the scorpion LCNs, SCNs and other biologically active peptides.

Animals↗
PubMed1994

[The modification of programmable pacemakers by therapeutic irradiation].

BACKGROUND: More than 300,000 pacemakers are implanted worldwide. During radiation therapy a damage of the pacemaker electronic is possible. METHODS: Twenty pacemakers have been irradiated with photons or electrons experimentally in three different situations: a) pacemaker and pacemaker electrode outside of the irradiation field: b) pacemaker outside, pacemaker electrode inside the irradiation field; c) all things inside the irradiation field. RESULTS: The voltage in the pacemaker electrode produced by the electric field of the accelerator did not exceed 0.8 mV if the electrode was outside the irradiation field. Induced voltage was up to 1.2 mV during irradiation with electrons (18 MeV) and the electrode being inside the treatment field with more than two thirds of its length. After delivering of not more than 10 Gy (photons) to the pacemaker, a decreasing amplitude of the pacemaker pulse occurred. The pulse frequency did not show any deviation. This seems to signal a severe early irreversible damage of the pacemaker that may cause sudden breakdown days or weeks after radiation. Two pacemakers showed a complete breakdown after irradiation with not more than 10 Gy. The others had a complete breakdown beyond doses of 50 Gy. CONCLUSIONS: It is recommended to keep CMOS pacemakers outside the treatment field and to explant if the dose to it was higher than 10 Gy.

Electrons↗
PubMed1989

[How safe are older x-ray generators].

An incident with a high-voltage generator more than 25 years old was the occasion for a discussion of the safety of such generators. A control timer broke down during the exposure period, and before the radiographer was able to react the X-ray tube imploded. The young patient suffered increased exposure and partial grade 3 burns. If such a breakdown occurs during exposure the radiographer has to turn off the generator by hand. This is the only way of preventing injury to the patient. Owners of such units must be aware of their particular responsibility and should train their personnel accordingly. In case of a breakdown only well-trained staff can act immediately, in the knowledge that only a few seconds are available before the patient suffers physical injuries. The fault mentioned should have been expected and it could happen again any time with such an old installation.

Germany, West↗
PubMed1988

[High-contrast radiographs for field control and field documentation in radiotherapy with high-energy photons].

In ambitious radiotherapy with individually shaped irradiation fields, high-contrast field radiography is necessary for fine adjustment, control and field documentation. If intensification foils made of materials with medium or high atomic numbers such as copper, iron and lead are used, the film lying between the foils is mainly darkened by the secondary electrons released from the material of the front foil. Within the range of 1 MeV to 15 MeV, high-contrast radiographs are produced by means of copper or steel foils which are clearly superior to lead foils. Steel foils are to be preferred to copper foils because of their rigidity and the firmness of the polished surface. Usual X-ray diagnosis films with steep graduation can be used as film material for field control radiography performed in double exposure technique. A new insensitive film not applied hitherto in X-ray diagnosis allows to prepare field documentation images of high quality which are exposed during the whole irradiation time. This is also important for perpetuation of evidence.

Humans↗
PubMed1988

[The new x-ray ordinance].

The new ordinance on X-ray irradiation, which was passed on 8 January 1987 and comes into force on 1 January 1988, is designed to keep radiation exposure during X-ray examinations to the minimum absolutely necessary. This is to be achieved not only by improving the specialist qualifications of the personnel concerned, but also by improved quality control. Substantial changes in X-ray diagnosis procedures will be introduced with the expected guidelines on implementation of the new decree.

Germany, West↗
PubMed1983

[Side effects of the treatment of cervix cancer].

Between 1962 and 1980, 237 patients with carcinomas of the cervix have been treated at the Radiologic Hospital of the University of Münster. With respect to the year of the treatment, six groups were formed depending on the observation period which was one year, two years, three years, four years, five years or more than five years. 68 women (29%) out of these groups had vesical reactions and 116 (49%) intestinal reactions. Most of the bladder reactions were early reactions appearing during the first three months, and the rate of vesical and intestinal troubles was higher after combined therapy with operation and irradiation than after primary radiotherapy. The therapy effects to bladder and intestine were classified by a method proposed by Holstein and Hess according to which even insignificant troubles are taken into consideration. 15 patients had stases concerning the ureters or kidneys. In five cases a rectovaginal fistula and in four cases a vesicovaginal fistula was demonstrated as a therapy effect. Furthermore, the following reactions were observed: radiation sickness, cutaneous reactions, marked vaginal fluor, heavy lumbago, general abdominal troubles, vaginal bleedings, fever after the insertion of radium as well as thrombosis and embolism.

Female↗
PubMed1979

[Diabetes mellitus and coronary disease--common problems in long-term care].

With the help of a comparative analysis of the cardiovascular risk profile of 150 patients with diabetes mellitus, 62 patients with condition after myocardial infarction and 50 control patients of a rural district with 30,000 inhabitants was established that the spectre of the risk factors widely corresponds. According to a point valuation the diabetics on an average reached 3.36 points and the patients with a condition after myocardial infarction reached 2.66 points. In comparison of the curves a nearly identical course with "a shift to the right" of the patients with diabetes mellitus about the factor of the disturbance of the glucose metabolism could be proved. Concluding from this a general conception of the treatment was described. In this case the aim is a balanced therapy of the factors of risk and a preventive physical conditioning of diabetics with a high risk of infarction. In our investigations was furthermore conspicuous, deviating from literature, a very large proportion of patients with a hyperuricaemia (33.3% of the diabetics, 41.9% of the patients with infarction).

Adult↗