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J Bammert

Publications and source records attributed to J Bammert.

10 recordsLinked to original sources
PubMed2005

Stripe-hexagon competition in forced pattern-forming systems with broken up-down symmetry.

We investigate the response of two-dimensional pattern-forming systems with a broken up-down symmetry, such as chemical reactions, to spatially resonant forcing and propose related experiments. The nonlinear behavior immediately above threshold is analyzed in terms of amplitude equations suggested for a 1:2 and 1:1 ratio between the wavelength of the spatial periodic forcing and the wavelength of the pattern of the respective system. Both sets of coupled amplitude equations are derived by a perturbative method from the Lengyel-Epstein model describing a chemical reaction showing Turing patterns, which gives us the opportunity to relate the generic response scenarios to a specific pattern-forming system. The nonlinear competition between stripe patterns and distorted hexagons is explored and their range of existence, stability, and coexistence is determined. Whereas without modulations hexagonal patterns are always preferred near onset of pattern formation, single-mode solutions (stripes) are favored close to threshold for modulation amplitudes beyond some critical value. Hence distorted hexagons only occur in a finite range of the control parameter and their interval of existence shrinks to zero with increasing values of the modulation amplitude. Furthermore, depending on the modulation amplitude, the transition between stripes and distorted hexagons is either subcritical or supercritical.

Journal Article↗
PubMed1987

Endogenous agonists may change the concentration-response curves of exogenous agonists: source of quantitative information about the endogenous tone.

The "pharmacological dogma" that competitive antagonists cause parallel shifts to the right with sustained maximum effect of semi-logarithmic concentration-response curves of exogenous agonists may not be true if an endogenous agonist is present in the preparation. In this case, the antagonist and the exogenous agonist interfere in a complex way with an existing circuit of regulation between the response and the endogenous agonist. In consequence, it is difficult to determine the true shift in the concentration-response curves as induced by the antagonist, since a deviation of the curves in a non-parallel manner can be observed. The extent of this deviation may be used to learn more about the variables involved. The present paper discusses this phenomenon: The regulatory circuit of the (auto)receptor modulated release of neutrotransmitters is used as an example. Paired samples of data are analysed in this example. Since the extent of the non-parallel deviation also depends on the manner in which the paired samples are mathematically linked, two different ways of data evaluation have been used. A theoretical model of the relation between receptor activation and response is proposed which allows to evaluate experimental concentration-response curves by means of non-linear regression analysis. This evaluation yields quantitative information on the parameters of the regulatory circuit: the concentration of the endogenous agonist, its KD value and the true shift of the concentration-response curve caused by the applied antagonist.

Animals↗
PubMed1985

[Diagnosis and therapy of Hodgkin's disease in Freiburg in Breisgau 1964 to 1976. 1. Report of the complete collective].

Between May 1964 and December 1976, 370 patients with Hodgkin's disease (CS/PSIn = 41 [11.2%], CS/PSIIn = 148 [40.2%], CS/PSIII n = 148 [40.2%], CS/PSIV n = 31 [8.4%] with different diagnoses were treated by different therapies, 250 out of them (67.5%) only by radiotherapy (local, extended, and total lymphoid irradiation), 115 (31%) by radiotherapy and chemotherapy, and five patients in stage IV (1.5%) only by chemotherapy. The first treatment divides the patients into three subgroups with significantly different prognoses: 1. a subgroup with complete remission assessed half a year after the end of therapy (n = 206 [58%]) and a healing rate of 96.2%; 2. a subgroup with partial remission (n = 62 [17.5%]) and a healing rate of 51.6%; 3. a subgroup without remission (n = 87 [24.5%]) and a healing rate of 4.2%. In case of recurrence after complete or partial remission, another complete and durable remission is achieved by subsequent therapy in about 85% of patients with preceding complete remission and statistically about 50% of patients with preceding partial remission. The overall five-year survival rate is 73.1%; a constant level of 67.3% (statistical healing rate) is observed after seven years. The following risk factors for remission have been found: the histologic manifestation lymphocytic depletion, parts of stage III, especially of type B, stage IV, and an age above 40 years and even more above 50 years.

Adolescent↗
PubMed1985

[Diagnosis and therapy of Hodgkin's disease in Freiburg in Breisgau 1964 to 1976. 2. Results during the treatment period 1972-1976 compared with the period 1964-1971].

The total group of patients with Hodgkin's disease submitted to primary treatment from May 1964 till December 1976 is divided with respect to diagnostics and therapy into a preponderantly clinically assessed group (CS) treated during the years of 1964 to 1971 (n = 190) and a preponderantly surgically assessed group (PS) treated during the years of 1972 to 1976 (n = 180). The first subgroup was treated with differently large irradiation fields and, in case of combined therapy, mostly with cyclophosphamide. The second subgroup was treated with extended fields, even until total lymphoid irradiation and, in case of drug administration, with primary combined chemotherapy (MOPP). The overall five-year remission rates of both subgroups (stages I to IV) have improved from 35.4% to 54.8% (P less than or equal to 0.001) and the five-year survival rates from 67.2% to 78.2% (P less than or equal to 0.001). If a complete remission was achieved, this was obtained, as far as judgeable, already at an earlier moment in the individual groups: e.g., in stage I with 95.5% after one year as against 94.1% after five years and in stage II with 91.3% after four years as against 72.9% after seven years. The prognostic differences of stages I and II and the histologic manifestations: lymphocytic predominance, nodular sclerosis, and mixed cellularity were equalized under the therapeutic measures of the intensive treatment period.

Adolescent↗
PubMed1984

Cytology of prostatic carcinoma. Quantification and validation of diagnostic criteria.

The validity of diagnostic criteria for the cytologic differentiation between benign and malignant cases and between normal (hyperplastic) and inflammation-activated (prostatitis) prostatic cells was tested by means of semiautomated image analysis and cytophotometry. The following criteria were found to have significant differences between benign and malignant prostatic cells: nucleoli (number, size and size variability), regularity of nuclear arrangement, anisonucleosis, nuclear size, nuclear polymorphism and dissociation of cells. The following criteria were found to be invalid for the detection of prostatic cancer cells: nuclear-cytoplasmic ratio, hyperchromasia and anisochromasia. the cytologic diagnosis of prostatic cancer was achieved by observing a variable constellation of at least three of six pathognomically altered diagnostic criteria. No fixed pattern of diagnostic criteria was found either for prostatic cancer cells in general or for the different malignancy grades.

Analysis of Variance↗
PubMed1977

[Morphometric differentiation of tumor and inflammation in angiography (author's transl)].

The angiographic differential diagnosis of malignant, benign and inflammatory lesions should be facilitated by mathematical analysis of the underlying vascular structure. A rotating screen with parallel lines -- especially developed for this purpose -- is used for the first time to verify statistically essential criteria in tumor diagnosis. Random samples are taken from 2 kidneys with severe inflammatory lesions and 1 hypernephroma in order to extract mathematical indices for fluctuation of caliber, vascular avulsion, change of direction and diameter. The index for the flucutation of caliber is the single most important criterion to differentiate the vascular structure of tumor and inflammation.

Adenocarcinoma↗
PubMed1976

Neutrophil marrow release. A system analysis.

Neutrophil marrow egress is governed by several processes. The most important are cell maturation, functional behavior of marrow sinusoids and humoral or neuro-vascular factors. Neutrophil release cannot be observed directly but is reflected in the size, cellular composition and kinetics of the nonproliferating pool of granulocytopoiesis in bone marrow and of blood neutrophil pool. These experimentally determined parameters were used as the basis of a mathematical model study. The model describes two catenated compartments, the nonproliferating pool of granulocytopoiesis in marrow and the total blood granulocyte pool. Cell transit from one pool to the other was assumed to be age-dependent. It was expressed by a positive sloping sigmoidal function that defines the egress potential fo the cells that increases with cell maturation. During maturation granulocytopoietic cells develop intense motility which determines the morphology of the cells on smears. Relationship between cell motility and its morphology was defined by functions determining the age-dependent probabilities of cell fixation as metamyelocytes, band- and segmented forms, respectively. The parameters of this model could be so adjusted that all experimental data were matched within experimental errors. Thus, qualitative and quantitative information on neutrophil marrow egress was obtained for normal and pathological states of granulocytopoiesis.

Age Factors↗
PubMedDate not supplied

Angiomorphometry in malignant tumors and inflammatory disease.

Angiographic differentiation of malignant and inflammatory lesions is occasionally impossible, since certain criteria for malignancy also apply to benign lesions. The authors analyzed samples of microangiographic specimens of kidneys with inflammation, tumor, and normal control organs to define mathematically the frequency of such angiographic parameters as caliber fluctuation, vascular avulsion, change of direction and diameter, and change in predominant vascular structure. The described method is transferred to clinical angiograms, and results of both groups are compared. In this preliminary analysis, caliber fluctuation appears to be the single most important criterion for differentiation of malignant and benign angiographic alterations.

Adenocarcinoma↗