Die Wirkungen von Eserin, Cholin und Glucose auf die Synthese und die Freisetzung von Acetylcholin im Darm

Zusammenfassung Die Wirkungen von Eserin, Cholin und Glucose auf die Freisetzung und die Synthese von Acetylcholin (ACh) wurden im isolierten Dünndarm des Meerschweinchens durch Bestimmungen des ACh-Gehaltes des Gewebes und der ACh-Freisetzung in die Badelösung untersucht.In Lösungen, die Eserin, Cholin und Glucose enthielten, nahm der ACh-Gehalt des Gewebes zu, und es erfolgte eine Freisetzung von ACh in die Badelösung. Die Zunahme des ACh-Gehaltes des Gewebes, welche nur in Eserin-haltigen Lösungen auftrat, konnte auf intracelluläre Anhäufung von ACh zurückgeführt werden.ACh wurde auch in Cholin-freien Lösungen synthetisiert, doch war die ACh-Synthese geringer als in Gegenwart von Cholin. Aus der ACh-Synthese in Cholinfreier Lösung und dem Anteil des Nervengewebes am Darmvolumen wurde die Cholinkonzentration im Nervengewebe berechnet. Es zeigte sich, daß die intracelluläre Cholinkonzentration viel größer als die Cholinkonzentration im Plasma war. Die Cholinaufnahme in das Nervengewebe scheint deshalb in vivo durch aktiven Transport zu erfolgen.Bei Fehlen von Glucose trat keine Synthese von ACh auf, die Freisetzung von ACh hingegen war etwa doppelt so groß wie in Glucose-haltiger Lösung. Die Erhöhung der ACh-Freisetzung nach Glucose-Entzug könnte eine Anzahl der Symptome des hypoglykämischen Schockes erklären.

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Summary The effects of eserine, choline, and glucose on the liberation and the synthesis of acetylcholine (ACh) were studied in the guinea pig's small intestine by measuring the ACh content of the tissue and the amount of ACh liberated in the bath.Incubation in solutions containing eserine, choline, and glucose caused an increase in the ACh content of the tissue and the liberation of ACh. The increase in tissue content, which was only found when eserine was present, appears to result from intracellular accumulation of ACh.ACh was also synthezised in choline free solution, but the amounts were smaller than in the presence of choline. Estimation of the choline concentration in the nervous tissue, from the ACh synthesis in choline free solution and the amount of nervous tissue in the intestine, shows that the choline concentration in nerve is much higher than in plasma. It is suggested that uptake of choline in vivo necessitates an active transport process.No synthesis of ACh was found in the absence of glucose; the liberation of ACh was increased and occured entirely on account of the initial ACh content. The increase in ACh liberation after glucose withdrawal might explain some symptoms of hypoglycemic shock.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Separation and mapping of multiple genes that control IgE level in Leishmania major infected mice

The strain BALB/cHeA (BALB/c) is a high producer, and STS/A (STS) a low producer of IgE after Leishmania major infection. We analyzed this strain difference using 20 recombinant congenic (RC) BALB/c-c-STS/Dem (CcS/Dem) strains that carry different random subsets of 12.5% of genes of the strain STS on the BALB/c background. Strains CcS-16 and -20 exhibit a high and a low IgE level, respectively. In their F(2) hybrids with BALB/c we mapped nine Leishmania major response (Lmr) loci. Two of them we previously found to influence IgE level in CcS-5. IgE production in CcS-16 is controlled by loci on chromosomes 2, 10, 16 and 18 and in CcS-20 by loci on chromosomes 1, 3, 4, 5 and 8. The STS alleles of loci on chromosomes 1, 4, 5, 8 and 10 were associated with a low, whereas the STS alleles on chromosomes 16 and 18 with a high IgE production. The loci on chromosomes 2 and 3 have no apparent individual effect, but interact with the loci on chromosomes 10 and 1, respectively. The loci on chromosomes 10 and 18 were mapped in the regions homologous with the human regions containing genes that control total serum IgE and intensity of infection by Schistosoma mansoni, suggesting that some Lmr loci may participate in the pathways influencing atopic reactions and responses to several parasites. The definition of genes controlling anti-parasite responses will permit a better understanding of pathways and genetic diversity underlying the disease phenotypes.     

HLA-DPB1 typing by polymerase chain reaction amplification with sequence-specific primers

DPB1 is the second most polymorphic class II locus with currently 84 recognized alleles, i.e. DPB1*0101 to DPB1*8101. Most of the alleles have been described during the last few years using oligonucleotide and sequencing techniques and relatively little is known about the role and importance of the polymorphic residues as regards to the function of DP molecules. In the present study, polymerase chain reaction (PCR) primers were designed for identification of all the phenotypically different DPB1 alleles by PCR amplification with sequence-specific primers. Forty-eight standard genomic PCR reactions per sample were performed in order to achieve this resolution. Unique amplification patterns were obtained in 2983 of 3160 (94.4%) possible genotypes. The primers were combined so that only very rare genotypes gave rise to ambiguous patterns. Sixty-four Histocompatibility Workshop cell lines and 150 DNAs provided by the UCLA DNA exchange were investigated by the DPB1 primer set. All typing results were conclusive. Analysis of the distribution of DPB1 alleles was performed in 200 Caucasian samples, 100 African samples and 40 Oriental samples. The population study by the DPB1 PCR-SSP method showed a characteristic distribution of HLA-DPB1 alleles. Each ethnic group had one, or two, frequent DPB1 allele(s) and the frequency of homozygotes was high, suggesting that balancing selection does not appear to be affecting the evolution of the DPB1 locus.     

Local environmental factors determine hematopoietic differentiation of neural stem cells

Stem cells exhibit unique properties and hold high therapeutic promise, but factors influencing their differentiation after transplantation need to be recognized and defined for this promise to be fully met. Here, we demonstrate that endogenous colony-forming unit spleen (CFU-S) colonies are not generated in lethally irradiated mice transplanted with neural stem cells obtained from brain tissue of syngeneic donors. We investigated the proportion of transplanted neural stem cells that contributed to hematopoietic reconstitution and compared the distribution of transplanted cells in nonsplenectomized to that of splenectomized mice following sublethal whole-body irradiation. We also used clonogenic assays, colony assays, and histochemical analyses to explore conditions under which transplanted, beta-galactosidase-tagged neural stem cells underwent hematopoietic differentiation. Our results suggest that neural stem cells do undergo extramedullary hematopoiesis, even while no endogenous hematopoietic colonies develop in the spleen. Furthermore, we found that neural stem cells effectively colonized the bone marrow of splectomized recipients. We conclude that the hematopoietic differentiation of neural stem cells is highly dependent on the extramedullary environment. We also conclude that the bone marrow does not provide an environment supportive of hematopoietic differentiation by neural stem cells.     

Structure of synovial lymphatic capillaries in rheumatoid arthritis and juvenile idiopathic arthritis

The structure of lymphatic capillaries (LC) of the synovial membrane (SM) from patients with rheumatoid arthritis and juvenile idiopathic arthritis obtained by synovectomy was investigated by transmission electron microscopy. This method allows comparison of the structure of the same vessel under light and electron microscope and clear differentiation between lymphatic and blood capillaries and venules. Synovial LC were localized in the subintimal connective tissue of the SM in the vicinity of venules. The shape of some LC was irregular, suggesting edema of the interstitium. Lymphatic endothelium has extremely attenuated cytoplasm with the exception of the perinuclear region. Many nuclei of endothelial cells had distinct nucleoli. The basal lamina was discontinuous. The walls of LC showed close connection with the interstitium represented by anchoring filaments that were attached to the endothelial cells and to the surrounding connective tissue. In some LC connective tissue appeared to be disconnected from endothelium and gaps between their walls and the interstitium were seen. Mononuclear cells were accumulated adjacent to some LC. Specialized interendothelial junctions (endothelial microvalves) were observed in the LC walls. Their structure and function in the migration of cells and debris from synovial interstitium into LC lumina in rheumatoid arthritic synovium deserves further investigation. In the lumina of some of the LC lymphocytes, monocytes, macrophages, cell debris and enlarged endothelium were observed. Accumulation of such material may cause obstruction of tiny LC. We suggest that reported alterations of the fine synovial lymphatic vessels can contribute to the progression of the inflammatory process to chronicity.     

The influence of obesity on the frequency and distribution of medication

Obesity is a serious health problem in industrialized countries and is associated with a significant increase in total health care costs. Only few data are available about the costs of drug therapies in patients with an increased body weight treated under clinical routine procedures. Such data could support efforts to intensify obesity prevention and treatment programmes in order to reduce comorbidities and costs. We have evaluated body mass index (BMI), diagnosis, and medication in 3360 outpatients (2175 women and 1185 men; mean age: 56.7 +/- 17.5 years). All patients underwent physical examinations, including BMI determination, and provided a detailed record concerning medication. In 1809 patients, the percentage of body fat content was measured with a bioimpedance method (OMRON BF 302 body fat monitor). Continuous variables were compared using the t-test or Wilcoxon U-test. Frequency distributions were compared using chi-squared tests. With respect to BMI, most of the patients (n = 1793; 53 %) were overweight or obese, 1349 (40 %) showed a normal BMI and 218 (7 %) a low BMI. The majority of cardiovascular (61 %), rheumatological (61.1 %) and metabolic (60.4 %) medication was administered to overweight and obese patients. Parallel findings could be obtained by analysing the percentage of body fat and the frequency of medication. Overall, 82.5 % of all medication was given to patients with a body fat content >20 %. Our results support the importance of weight-reduction programmes in order to prevent an overall increase in the costs of medication as a consequence of overweight and obesity.     

The epidemic wave of meningococcal disease in Spain in 1996-1997: probably a consequence of strain displacement

During 1996 and 1997 an epidemic wave of meningococcal disease took place in Spain. Initial studies described the antigenic expression of the epidemic strain as C:2b:P1.2,5 and proposed that it was a variant of the previously identified Spanish C:2b:non-subtypable epidemic strain. To clarify this hypothesis, 1036 C:2b:P1.2(5) and 76 C:2b:NST isolates obtained during 1992-1999 were analysed by pulsed-field gel electrophoresis. The majority of the C:2b:P1.2,5 and C:2b:P1.2 isolates showed one of two very closely related profiles. During the epidemic period, 80% of the C:2b:NST strains showed these two pulsotypes. However, before the epidemic wave, most of these C:2b:NST strains (60%) showed a profile that was found infrequently among C:2b:P1.2,5 and C:2b:P1.2 isolates. A similar evolution was observed in C:2b:P1.5 isolates. Thirty-four C:2b:P1.2(5) and 10 C:2b:NST isolates, exhibiting representative pulsotypes, were subjected to multi-locus sequence typing. Isolates belonging to both A4 and ET-37 lineages were identified. These data point to the possibility that the A4 cluster has displaced the ET-37 complex among serogroup C meningococci in Spain.     

Cell-cell and cell-matrix interactions during initial enamel organ histomorphogenesis in the mouse

Relationships between cell-cell/cell-matrix interactions and enamel organ histomorphogenesis were examined by immunostaining and electron microscopy. During the cap-bell transition in the mouse molar, laminin-5 (LN5) disappeared from the basement membrane (BM) associated with the inner dental epithelium (IDE), and nondividing IDE cells from the enamel knot (EK) underwent a tooth-specific segregation in as many subpopulations as cusps develop. In the incisor, the basement membrane (BM) in contact with EK cells showed strong staining for LN5 and integrin alpha 6 beta 4. LN5 seems to provide stable adhesion, while its proteolytic processing might facilitate cell segregation. In both teeth, immunostaining for antigens associated with desmosomes or adherens junctions was similar for EK cells and neighboring IDE cells. Outside the EK, IDE cell-BM interactions changed locally during the initial molar cusp delimitation and on the labial part of the incisor cervical loop. Conversely, cell-cell junctions stabilized the anterior part of the incisor during completion of morphogenesis. Time and space regulation of cell-matrix and cell-cell interactions might thus play complementary roles in allowing plasticity during tooth morphogenesis and stabilization at later stages of epithelial histogenesis.     

Is factor V Leiden a risk factor for fetal loss?

A successful pregnancy is dependent on the development of adequate placental circulation. The abnormalities of placental vasculature may result in a number of gestational pathologies, including fetal loss. The aim of our study was to determine whether women with f V Leiden are at an increased risk of pregnancy loss. For this purpose we assessed three groups of women. In a prospective group we examined 30 females with spontaneous abortions for f V Leiden. In a retrospective group we assessed the frequency of abortions in 80 women (172 pregnancies) with f V Leiden (72 heterozygous, 8 homozygous) from 57 unrelated families. In a control group we evaluated the frequency of abortions in 45 women without f V Leiden. Factor V Leiden was found in 3% of women in the 1st group. Fetal loss occurred in 10% of women in the 2nd group and in 9% in the 3rd group. Factor V Leiden was not found to be a risk factor for fetal loss in our study group.     

The myelin basic protein-specific T cell repertoire in (transgenic) Lewis rat/SCID mouse chimeras: preferential Vβ8.2 T cell receptor usage depends on an intact Lewis thymic microenvironment

In the Lewis rat, myelin basic protein (MBP)-specific, encephalitogenic T cells preferentially recognize sequence 68–88, and use the Vβ8.2 gene to encode their T cell receptors. To analyze the structural prerequisites for the development of the MBP-specific T cell repertoire, we reconstituted severe-combined immunodeficient (SCID) mice with fetal (embryonic day 15–16) Lewis rat lymphoid tissue, and then isolated MBP-specific T cell lines from the adult chimeras after immunization. Two types of chimera were constructed: SCID mice reconstituted with rat fetal liver cells only, allowing T cell maturation within a chimeric SCID thymus consisting of mouse thymic epithelium and rat interdigitating dendritic cells, and SCID mice reconstituted with rat fetal liver cells and rat fetal thymus grafts, allowing T cell maturation within the chimeric SCID and the intact Lewis rat thymic microenvironment. Without exception, the T cell lines isolated from MBP-immunized SCID chimeras were restricted by MHC class II of the Lewis rat (RT1.B¹), and none by I-A^d of the SCID mouse. Most of the T cell lines recognized the immunodominant MBP epitope 68–88. In striking contrast to intact Lewis rats, in SCID mice reconstituted by rat fetal liver only, MBP-specific T cell clones used a seemingly random repertoire of Vβ genes without a bias for Vβ8.2. In chimeras containing fetal Lewis liver plus fetal thymus grafted under the kidney capsule, however, dominant utilization of Vβ8.2 was restored. The migration of liver-derived stem cells through rat thymus grafts was documented by combining fetal tissues from wild-type and transgenic Lewis rats. The results confirm that the recognition of the immunodominant epitope 68–88 by MBP-specific encephalitogenic T cells is a genetically determined feature of the Lewis rat T cell repertoire. They further suggest that the formation of the repertoire requires T cell differentiation in a syngeneic thymic microenvironment.