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Biomedical subjects

H J Krüger

Publications and source records attributed to H J Krüger.

14 recordsLinked to original sources
PubMed1991

[MR imaging of a giant solitary trichoepithelioma of the skin].

Magnetic resonance images of a "giant solitary trichoepithelioma" (GST) are presented for the first time. Furthermore, to our knowledge this is the largest GST ever to be reported in the current literature. Magnetic resonance imaging gave information on the origin of the tumor and on the depth of invasion. The signal intensity is non-specific and does not allow histological classification. Preoperatively, the MR examination depicts the extent of the tumor and thus helps in the surgical management that follows.

Aged↗
PubMed1990

Flow cytometric determination of the time of metastasis during fractionated radiation therapy of the rat rhabdomyosarcoma R1H.

A technique is presented for determining the time of metastasis during fractionated radiation therapy of the rat rhabdomyosarcoma R1H by flow cytmetric DNA index measurements. The DNA index is the relative DNA content of the tumour cells compared with normal cells. The DNA index of the highly hyperploid R1H tumour decreases linearly during radiation therapy dependent on the total dose applied, with a rate of 0.22% per Gy. Since metastatic cells escape further irradiation, their DNA index should correspond to the DNA index at time of spread. If so, cells disseminated late during a course of fractionated irradiation are expected to produce symptoms later and to have a lower DNA index compared with cells that metastasized at the start of treatment. The results obtained fitted these expectations, showing that timing of metastases by DNA flow cytometry, in principle, is possible. A first application of this method indicates that the risk per clonogenic R1H tumour cell to matastasize increases during fractionated irradiation.

Animals↗
PubMed1990

Cell population kinetics of the rhabdomyosarcoma R1H of the rat after single doses of X-rays.

The kinetics of depopulation and repopulation of the solid transplantable rhabdomyosarcoma R1H of the rat following local irradiation with single subcurative X-ray doses of 7.5, 15 and 30 Gy was studied. Several parameters were sequentially measured over a time interval of 4 weeks after irradiation: the ratio of the number of tumour to host cells, and the cellular DNA content of tumour and host cells, were determined by flow cytometry; the amount of DNA per gram of tumour tissue was determined biochemically; the clonogenic fraction of tumour cells was obtained from in vitro colony assay; and the tumour volume was assessed by in situ caliper measurements. From the amount of DNA per gram and the average DNA content per cell, the total number of cells per gram of tumour tissue was obtained. From this and the other parameters measured, the number of clonogenic tumour cells, non-clonogenic tumour cells and nucleated host cells per tumour, as well as their variation with time and dose, could be derived. The results showed that there was a lag period prior to depopulation amounting to 3.8 +/- 1.4, 1.4 +/- 0.8 or 0 +/- 0.7 days for 7.5, 15 or 30 Gy, respectively. The rate of depopulation of non-clonogenic tumour cells increased with dose; the halving times of non-clonogens were 4.7 +/- 1.8, 2.6 +/- 0.7 or 2.1 +/- 0.4 days for the three doses applied. There were no indications that proliferation of doomed cells contributed significantly to tumour growth after irradiation. After lag periods that were similar in length to those prior to depopulation, a massive immigration of host cells was observed. Under certain conditions more than 97 per cent of the cells present in irradiated tumours were found to be of host origin. There was a lag period before the onset of repopulation by clonogenic tumour cells, the length of which increased from 2.7 +/- 0.7 to 5.0 +/- 0.8 or 6.3 +/- 1.0 days for 7.5, 15 or 30 Gy, respectively. The initial rate of repopulation increased with radiation dose; after the end of the lag period the doubling time of clonogenic tumour cells (in controls amounting to 3.7 +/- 0.2 days) was 3.1 +/- 0.1, 2.1 +/- 0.1 and 1.1 +/- 0.1 days for the three doses applied.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Haptoglobin subtyping by isoelectric focusing in ultrathin-layer polyacrylamide gels. Population genetic data for Hanover and Lower Saxony.

This report describes a method for subtyping haptoglobin by means of isoelectric focusing in 0.2-mm ultrathin-layer polyacrylamide gels. Haptoglobin (Hp) is purified by ion-exchange chromatography and reduced. The well-known advantages of ultrathin-layer gels combine high isoelectrophoretic resolution of the Hp subtypes with less demands for time and material and make sequential visualization by fixation and protein staining possible. The distribution of the Hp subtypes in 1500 unrelated adults from Hanover and Lower Saxony is presented. Allelic frequencies are calculated to be: Hp*2FF = 0.0030; *2FS = 0.5620; *2SS = 0.0290; *1F = 0.1537; *1S = 0.2523. Segregation analysis for 68 matings shows an autosomal codominant mode of transmission in all cases. For the population investigated the chance of isolated paternity exclusion with the subtyped Hp system amounts to 33.91%.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

[A new Y-endoprosthesis for drainage of bile duct obstruction of the hepatic bifurcation].

Biliary decompression in cases of central tumorous biliary obstruction requires surgical or internal/external catheter bypass techniques. The development of a 14-F Y-shaped-polyurethane endoprosthesis stent provides the possibility to drain the left and right biliary system simultaneously. The endoprosthesis is placed by a combination of external transhepatic and endoscopic approach. The tip of the singular choledochal stent segment is placed within the choledochus or duodenum.

Cholestasis, Intrahepatic↗
PubMed1984

Desulfovibrio vulgaris hydrogenase: a nonheme iron enzyme lacking nickel that exhibits anomalous EPR and Mössbauer spectra.

A purification procedure for the periplasmic hydrogenase from Desulfovibrio vulgaris ( Hildenborough , National Collection of Industrial Bacteria 8303) is reported. The purified hydrogenase has a specific activity of 4800 units per mg of protein. Plasma emission studies reveal that this highly active hydrogenase is free of nickel and contains 11 (+/- 1) nonheme iron atoms per molecule. A combined EPR and Mössbauer study indicates that the majority of the iron atoms are bound in the form of iron- sulfur clusters. Two ferredoxin-type [4Fe-4S] clusters have been identified that exhibit normal EPR and Mössbauer parameters; however, no trace of 3Fe cluster is detected by the Mössbauer measurement. In the presence of oxidants, cytochrome c3, and CO, anomalous EPR and Mössbauer spectra indicative of atypical nonheme iron centers are observed.

Carbon Monoxide↗
PubMed1982

Evidence for nickel and a three-iron center in the hydrogenase of Desulfovibrio desulfuricans.

Hydrogenase from Desulfovibrio desulfuricans (ATCC No. 27774) grown in unenriched and in enriched 61Ni and 57Fe media has been purified to apparent homogeneity. Two fractions of enzymes with hydrogenase activity were separated and were termed hydrogenase I and hydrogenase II. they were shown to have similar molecular weights (77,600 for hydrogenase I and 75,500 for hydrogenase II), to be composed of two polypeptide chains, and to contain Ni and non-heme iron. Because of its higher specific activity (152 versus 97) hydrogenase II was selected for EPR and Mössbauer studies. As isolated, hydrogenase II exhibits an "isotropic" EPR signal at g = 2.02 and a rhombic EPR signal at g = 2.3, 2.2, and 2.0. Isotopic substitution of 61Ni proves that the rhombic signal is due to Ni. Combining the Mössbauer and EPR data, the isotropic g = 2.02 EPR signal was shown to originate from a 3Fe cluster which may have oxygenous or nitrogenous ligands. In addition, the Mössbauer data also revealed two [4Fe-4S]2+ clusters iun each molecule of hydrogenase II. The EPR and Mössbauer data of hydrogenase I were found to be identical to those of hydrogenase II, indicating that both enzymes have common metallic centers.

Desulfovibrio↗
PubMed1982

[Inhibition of nocturnal acid secretion by pirenzepine (author's transl)].

The effect of 50 and 100 mg of 5,11-dihydro-11-[(4-methyl-piperazin-1-yl)acetyl]-6H-pyrido]2,3-b][1,4]benzodiazepin-6-one dihydrochloride (pirenzepine), respectively, given p.o. at 6 p.m. on nocturnal acid secretion was tested in 6 healthy volunteers. Pirenzepine showed a long-lasting antisecretory activity. The total acid output between 0 a.m. and 6 a.m. was reduced with 50 mg of pirenzepine by about 32% and with 100 mg of pirenzepine by about 41%. It is assumed that pirenzepine (100 mg at bedtime) should be tested in the prevention of relapse in chronic duodenal ulcer disease.

Benzodiazepinones↗