Quantitative 125J-Autoradiographie einzelner Zellen

Zusammenfassung Das nach der Energie seiner -Zerfälle zwischen Tritium und Kohlenstoff-14 liegende Isotop ¹²⁵J wurde auf seine Eignung zur quantitativen Autoradiographie geprüft. Absorption und Geometrie-Faktoren der radioaktiven Strahlung wurden untersucht. Hieraus ließen sich geeignete Meßbedingungen entwickeln. Durch gleichzeitige Exposition von radioaktiven Referenzquellen können absolute Radioaktivitätsmengen ermittelt werden. Als Referenzquellen sind membranmarkierte Standardzellen geeignet, die den physikalischen Eigenschaften des Isotopes Rechnung tragen. Hierzu wurden enzymatisch radiojodinierte Schaferythrozyten auf ihre Eignung geprüft. Die absolute Zahl von antigenen Stoffen auf den Oberflächen einzelner Zellen erhält man, wenn man die spezifische Aktivität der markierten Antikörpermoleküle bestimmt und die Silberkorndichte der zu untersuchenden Zellen und der Standardzellen mißt. Die Radioaktivität pro Standardzelle wird in herkömmlicher Weise ermittelt.Die neue Methode wurde zur Quantifizierung membrangebundener Immunglobulinmoleküle vom IgG-Typ auf einzelnen menschlichen Lymphozyten angewendet. Hierbei ist die Ermittlung einer immunologischen Sättigung des markierten Antikörpers wesentlich. Auf Lymphozyten von Normalpersonen und von chronisch-lymphatischen Leukämiepatienten konnten sehr unterschiedliche absolute Immunglobulinmengen bestimmt werden.

---

Quantitative ¹²⁵I-autoradiography of individual cells

Summary Iodine 125, an emitter of -radiation with an energy lying between that of tritium and carbon-14, is investigated for its applicability in quantitative autoradiography. Absorption and geometric factors of radiation are elucidated. From this, appropriate measuring conditions are derived. The simultaneous exposure of radioactive standard sources permits the evaluation of absolute amounts of radioactivity. Standard cells with labelled membranes are a suitable source of reference taking into account the physical properties of the isotope. Sheep red blood cells are examined for their suitability as standard cells after enzymatic radioiodination. The absolute number of antigenic substances on the surface of single cells is obtained by determining the specific activity of the labelled antibody molecules, and by measuring the silver grain densities of the cells under investigation and of the standard cells. The radioactivity per standard cell can be assessed by conventional procedures.The new method is applied to the quantification of membrane-bound immunoglobulin molecules of the IgG-type on single human lymphocytes. The determination of an immunologic saturation of the labelled antibody is essential for this purpose. On the lymphocytes of a normal person and of a patient with chronic lymphatic leukaemia quite different amounts of immunoglobulins have been evaluated.

---

---

Assoziation mit EURATOM 031-64 I BIAD.     

Nomenclatural adjustments in some European monocotyledons

New nomenclatural combinations are validated for fifteen taxa belonging to the generaDanthonia, Stipa, Lolium, Phippsia, Elymus, Schoenoplectus andAllium.     

Metabolic engineering of plant secondary metabolite pathways for the production of fine chemicals

The technology of large-scale plant cell culture is feasible for the industrial production of plant-derived fine chemicals. Due to low or no productivity of the desired compounds the economy is only in a few cases favorable. Various approaches are studied to increase yields, these encompass screening and selection of high producing cell lines, media optimization, elicitation, culturing of differentiated cells (organ cultures), immobilization. In recent years metabolic engineering has opened a new promising perspectives for improved production in a plant or plant cell culture.     

Gap junction remodeling and altered connexin43 expression in the failing human heart

Gap junctions (GJ) are important determinants of cardiac conduction and the evidence has recently emerged that altered distribution of these junctions and changes in the expression of their constituent connexins (Cx) may lead to abnormal coupling between cardiomyocytes and likely contribute to arrhythmogenesis. However, it is largely unknown whether changes in the expression and distribution of the major cardiac GJ protein, Cx43, is a general feature of diverse chronic myocardial diseases or is confined to some particular pathophysiological settings. In the present study, we therefore set out to investigate qualitatively and quantitatively the distribution and expression of Cx43 in normal human myocardium and in patients with dilated (DCM), ischemic (ICM), and inflammatory cardiomyopathies (MYO). Left ventricular tissue samples were obtained at the time of cardiac transplantation and investigated with immunoconfocal and electron microscopy. As compared with the control group, Cx43 labeling in myocytes bordering regions of healed myocardial infarction (ICM), small areas of replacement fibrosis (DCM) and myocardial inflammation (MYO) was found to be highly disrupted instead of being confined to the intercalated discs. In all groups, myocardium distant from these regions showed an apparently normal Cx43 distribution at the intercalated discs. Quantitative immunoconfocal analyis of Cx43 in the latter myocytes revealed that the Cx43 area per myocyte area or per myocyte volume is significantly decreased by respectively 30 and 55% in DCM, 23 and 48% in ICM, and by 21 and 40% in MYO as compared with normal human myocardium. In conclusion, focal disorganization of GJ distribution and down-regulation of Cx43 are typical features of myocardial remodeling that may play an important role in the development of an arrhythmogenic substrate in human cardiomyopathies.