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J Schumann

Publications and source records attributed to J Schumann.

At least 55 records · Page 3Linked to original sources
PubMed1985

Partial proteolysis as a probe of the conformation of the gamma subunit in activated soluble and membrane-bound chloroplast coupling factor 1.

Treatments that enhance the latent ATPase activity of the chloroplast coupling factor (CF1) also induce hypersensitivity of the gamma subunit toward trypsin. A number of different gamma subunit cleavage products are formed (Moroney, J. V., and McCarty, R. E. (1982) J. Biol. Chem. 257, 5910-5914). We have compared the gamma cleavage products of membrane-bound and isolated CF1, activated either by reduction of the gamma disulfide bond or by removal of the epsilon subunit. The gamma subunit of isolated CF1 lacking the epsilon subunit was cleaved to a 27,000-Da species. The same cleavage site became exposed following energy-dependent conformational changes in the membrane-bound enzyme. Activation by reduction of the gamma disulfide bond also exposed this site. However, the gamma subunit of reduced CF1 was cleaved rapidly at an additional site and trypsin treatment gave rise to a 25,000-Da gamma species. The small peptide generated by the second cleavage contains one of the cysteinyl residues of the reduced disulfide bridge of gamma. This peptide dissociates from the enzyme and can be isolated by gel filtration. The close proximity of the trypsin cleavage sites to the disulfide bond of gamma is discussed with respect to the effects of tryptic cleavage on the ATPase activity of CF1. The data indicate that structural changes in a limited region of the gamma subunit strongly influence the catalytic properties of both soluble and membrane-bound CF1.

2-Naphthylamine↗
PubMed1985

Differential pattern of DNA-aneuploidy in human malignancies.

The differential pattern of DNA-aneuploidy, detected by flow cytometry (FCM) regarding its frequency, grade and multiclonality, was investigated and correlated to tumor type, malignancy grade, tumor stage and prognosis in a multi-institutional study at the University of Münster. High resolution measurements using admixed normal blood reference cells were undertaken in 2413 cases of 13 different malignant diseases and in 776 benign lesions or samples. The incidence of DNA-aneuploidy was highest in melanomas, carcinomas, testicular tumors, sarcomas (75%-95%) and myelomas (65%). Acute leukemias showed an intermediate DNA-aneuploidy rate of 40% with special subgroups represented by common ALL (44%), p less than 0.05) and myelomonocytic/monocytic AML (47%, p less than 0.01). The lowest DNA-aneuploidy-rate was found in basal cell skin carcinomas (19%) and congenital melanocytic nevi (9%). No case of DNA-aneuploidy was observed in the 776 benign lesions or samples.--DNA-indices giving the grade of DNA-aneuploidy with 1.0 for normal diploid G1/0 cells were found distributed predominantly between 1.0 and 2.0 in the solid tumors, except testicular tumors, clustering around a triploid maximum at 1.5. DNA-indices of myelomas and acute leukemias generally ranged below 1.25 with lower DNA-aneuploidy grades in AML than in ALL (p less than 0.01).--In melanomas the aneuploidy rate was higher (86%) in metastases than in the primary tumors (54%, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Convention on nomenclature for DNA cytometry. Committee on Nomenclature, Society for Analytical Cytology.

Analysis of cellular DNA content by cytometry is important in clinical and biological research. Measurements are used widely to assess the relative DNA content of tumor stemlines and to assist in the detection and evaluation of malignant diseases. A review of the literature on DNA measurements in solid tumor and leukemias reveals a confusing variety of terms applied for the description of similar results. In order to facilitate the understanding of data and to standardize the terminology for DNA analyses, a questionnaire was distributed to more than 500 investigators. Subsequently, a workshop on terminology was held at the Combined Conference on Analytical Cytology and Cytometry IX and VIth International Symposium on Flow Cytometry, Schloss Elmau, West Germany, 18-23 October, 1982. The workshop nominated a nine-member committee to develop guidelines for nomenclature to be used in reporting results from analyses by DNA cytometry. The committee was charged by the Council of the Society for Analytical Cytology to complete this task and to publish its recommendations in Cytometry and in Cancer Genetics and Cytogenetics. The following guidelines are based on the questionnaires returned and the discussion at the workshop; they represent the unanimous recommendations of the committee. The five guidelines given herein apply to measurements of relative DNA content of cells that have been stained appropriately and analyzed by cytometry.

Animals↗
PubMed1984

DNA aneuploidy in congenital melanocytic nevi: suggestive evidence for premalignant changes.

Nuclei with abnormal (aneuploid) DNA content were detected by flow cytometric analysis in 4 of 39 congenital melanocytic nevi and in 0 of 62 acquired nevi. Three of the 4 nevi with DNA-aneuploidy were greater than 20 cm in their largest diameter. We suggest that DNA aneuploidy is an indicator of a premalignant condition in congenital nevi in cases where histologic examination does not reveal any evidence for malignant melanoma. Cells with abnormal DNA content (aneuploid cells) are not uniformly distributed in giant congenital nevi: in one lesion we observed an area with a high percentage of cells with DNA aneuploidy, areas with a low percentage of aneuploid cells, and parts that were found to be normal by flow cytometric analysis. Nuclear pleomorphism was found histologically in the area with the high percentage of aneuploid cells while the areas with the low percentage of aneuploid cells were histologically normal. Thus, flow cytometry seems to be an additional sensitive method for the detection of nuclear abnormalities that are not always apparent by conventional histology. Increase in the relative amount of growth phase (S-phase cells), indicating elevated proliferative activity, was detected in 6 of 39 congenital pigmented nevi and in 6 of 62 acquired nevi.

Adult↗
PubMed1983

[Multiple endocrine adenopathy type IIb. 15-years' observation of a case].

MEA IIb is a combination of C-cell carcinoma of the thyroid, phaeochromocytoma, multiple neuromas and a marfanoid habitus. A hyperplasia of the parathyroid cannot be found in most of the patients with this variant of Sipple's syndrome. In a 30-year-old woman, a MEA IIb could be observed over 15 years. Although primary surgery of the C-cell-carcinoma was insufficient, metastases were not found following two more surgical interventions in spite of elevated serum calcitonin. A phaeochromocytoma was not found, too. The reported case is compared with the literature.

Adult↗
PubMed1983

[Functional relations between the adrenal cortex, thyroid gland and pineal body. I. Reactions of the adrenal cortex following interference with the thyroid regulatory cycle].

Histologic-cytological and morphometrical changes were investigated in the adrenal cortex of male Wistar-rats in experimental hypo- and hyperthyroid situation. Under hypothyroid metabolism's situation (methylthiouracil-application or thyroidectomy) a regressive transformation was found: It is a decrease of secretion of the fascicular zone. The glomerular zone was activated. After long-time application of high dosis of thyroxin, the histological findings show some criteria of an increasing function and also of a beginning exhaustion, too. It is evident, that the duration of the hyperthyroid situation is important. Thyroxin is an unspecific stressor. The long-time application of high thyroxin dosis induced a regressive transformation and atrophic changes in the adrenal cortex. The nuclei of the fascicular and the glomerular zone were diminuated significantly.

Adrenal Cortex↗
PubMed1983

[Functional relations of the adrenal cortex, thyroid and pineal body. II. Adrenal cortex reaction following epiphysectomy and administration of melatonin].

Histologic-cytological and morphometrical changes were investigated in the adrenal cortex of male Wistar-rats following pinealectomy and application of melatonin in eu-, hypo-, and hyperthyroid situations. A rat experiment (at an average of 45 d) to find a possible functional connection between the pineal gland and the adrenal cortex was carried out. In the literature, there are only a few of informations about the role of the pineal in regulating ACTH secretion. The results are very contrarily. We found that pinealectomy is connected with a progressive transformation and melatonin with a little regressive transformation in the adrenal cortex. But, it is not evident, that the glomerular zone is activated after both pinealectomy and application of melatonin. In our opinion, the glomerular zone and the secretion of aldosterone increased after as well pinealectomy as melatonin. Application of melatonin diminishes the function of the pineal gland (see group 4-pinealectomy plus melatonin-where was found a progressive transformation). Under these experimental conditions, one can speak of a "pharmacological pinealectomy" after application of melatonin alone. However, the effect of melatonin on the fascicular zone and the glomerular zone is different. The effects of pinealectomy or application of melatonin in combination with methylthiouracil or thyroxin are relatively unimportant.

Adrenal Cortex↗
PubMed1982

Enhanced cell killing through the use of cell kinetics-directed treatment schedules for two-drug combinations in vitro.

Kinetics-directed drug treatment schedules were tested in Chinese hamster ovary cells. Ten hr after treatment with 1,2:5,6-dianhydrogalactitol (DAG) (at a dose lethal to less than 5% of the cells), a 150% enrichment of cells into the S phase of the cell cycle was observed. This blockade in S phase was reversible and was followed at 18 hr after an exposure to DAG by a 200% increase in the fraction of cells in the G2-M phases of the cell cycle. Bleomycin, known to be most effective against G2 + M cells, had the greatest effect on cell killing when administered at that time. Rapid analysis by flow microfluorometry techniques was used to determine the DAG-induced kinetics changes, thus allowing treatment with the second drugs at the most opportune time. The DAG-induced kinetics changes were also demonstrated in a line of human adenocarcinoma of the stomach in vitro and in Ehrlich ascites tumor cells in vivo. In all cases, the enrichment of cells into S phase was reversible at the doses used and was followed by a reversible blockade in G2-M.

Adenocarcinoma↗
PubMed1981

[TSH-secretion after surgery of decompensated autonomous thyroid adenomas].

The postoperative secretion rate of TSH before and after stimulation by TRF was studied in 43 patients with hyperfunctioning thyroid adenomas. TSH secretion is reduced and not at all or insufficiently stimulated by TRF preoperatively. This condition normalizes six weeks after operation. Mainly in those patients, who needed extensive resections of thyroid parenchyma basal TSH concentration and stimulation by TRF were elevated postoperatively. Following enucleations of adenomas or small resections we do not perform a substitution therapy, but control TSH-secretion rates in yearly intervals.

Adenoma↗
PubMed1981

[Conservative treatment of hyperthyroidism (author's transl)].

Antithyroid medication was given to 158 patients with hyperthyroidism over a period of 3 to 60 months. After cessation of therapy patients were followed up for 18 to 90 months. Permanent euthyroidism was seen in 70 patients (44.3%) after stopping treatment, however, 88 patients (55.7%) showed recurrence of hyperthyroidism occurring 1 to 56 months after ceasing treatment. In more than 50% recurrence of hyperthyroidism was within the first 3 months and in almost 80% within the first year after end of treatment. There was no connection either between the length of thyrostatic treatment and the recurrence rate or between the length of treatment and recurrence time. Comparison of patients with and without recurrence according to various parameters prior, during and after thyrostatic treatment indicates that there is a high risk of recurrence in patients with 1) nodular and (or) large goitres, 2) marked clinical symptomatology and delayed attainment of a euthyroid state after starting conservative treatment, and 3) the symptom of sweating remaining uninfluenced by antithyroid treatment.

Antithyroid Agents↗
PubMed1981

Mammalian spermatogenesis as a biologic dosimeter for radiation.

Mouse spermatogenesis was used as an in vivo test system obviously suitable as a biologic dosimeter. Ionizing irradiation induced changes in the frequency distribution of the cellular DNA content of whole testis preparations. These changes can be analysed by flow cytometry. Such measurements deliver information on: (1) an increase of the coefficient of variation of the DNA histograms of some spermatogenic cells, (2) induction of diploid mature sperm, and (3) the dose-depending inactivation of the highly sensitive differentiated spermatogonia. In this model especially No. 3 delivers quantitative information on the cytotoxic action of ionizing irradiation and chemical noxae as well, whereas Nos 1 and 2 may be used as qualitative criteria of mutagenic action of physical and chemical agents. No. 2 obviously being more sensitive than No. 1.

Animals↗
PubMed1981

[Morphological studies on the adrenal cortex of Wistar rats following lead poisoning and experimental hypothyroidism].

In a chronic experiment, male Wistar-rats were treated alone and in combination with methylthiouracil and lead acetate. Additionally, the animals of 2 groups were thyroidectomised. The suprarenal organs were investigated gravimetrically. Histologic-cytological and caryometrical investigations were made on the suprarenal cortex. After lead acetate application in the cortex, strong histologic-cytological alterations were obtained. There are marked damages especially in the zona fasciculata; a great number of pycnotic nuclei, a small subcapsular blastem, and a spreading out of the zona reticularis are observed. The size of nuclei is significantly diminished. These results indicated a regressive transformation and a toxic effect is discussed. After application of methylthiouracil or thyroidectomy, a regression transformation is found too. Cellular degenerations in all zones of the cortex are rarely or not obtained. As well methylthiourail as thyroidectomy diminish the weights of suprarenal organs high significantly. These results are not found after combined application of methylthiouracil and lead acetate. Methylthiouracil reduced the effect of lead acetate. The results allow to draw the following conclusion: In our opinion, a hypothetic methylthiouracil-lead-compound is built. This interpretation is supported by the persistent effect of lead acetate whenever lead acetate is combined with thyroidectomy.

Adrenal Cortex↗