Ontogeny, differentiation and growth of the endocrine pancreas

The pancreas develops from the primitive foregut endoderm, which differentiates into ductal, acinar and endocrine cells. This complex process is probably replicated in the adult pancreas when endocrine cell renewal is required, as may be the case in diabetes mellitus. This review describes what is known about the morphogenesis of the endocrine pancreas during ontogeny and the mechanisms regulating its differentiation and growth. Received: 23 December 1999 / Accepted: 15 February 2000     

Moraxella catarrhalis--infected alveolar epithelium induced monocyte recruitment and oxidative burst

The recruitment of monocytes appears to be a crucial factor for inflammatory lung disease. Alveolar epithelial cells contribute to monocyte influx into the lung, but their impact on monocyte inflammatory capacity is not entirely clear. We thus analyzed the modulation of monocyte oxidative burst by A549 and isolated human alveolar epithelial cells. Epithelial infection with Moraxella catarrhalis induced monocyte adhesion, transepithelial migration, and superoxide generation, whereas stimulation with lipopolysaccharide, tumor necrosis factor-alpha, interleukin-1beta, or interferon-gamma induced adhesion or transmigration, but failed to initiate monocyte burst. The effect of microbial challenge was mimicked by phorbol myristate acetate and inhibited by the protein kinase C inhibitor bisindoylmaleimide. Furthermore, evidence for a role of platelet-activating factor-signaling in monocytes is presented. Monocyte burst was neither induced by supernatant nor affected by fixation of A549 cells, excluding the contribution of epithelium-derived soluble factors but emphasizing the mandatory role of intercellular contact. The employment of blocking antibodies, however, denied a role for the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, or CD11b/CD18 and CD49d/CD29. In essence, infection of alveolar epithelial cells with M. catarrhalis might amplify the inflammatory capacity of invading monocytes eliciting their superoxide production. The epithelial response to this microbial challenge thus clearly differed from that to proinflammatory cytokines.     

Polymere Aminoschutzgruppen. Synthese von neuen poly[2-(N-vinylpyridinio)ethoxycarbonyl]-,2-(N-pyridinio)ethoxycarbonyl- und 2-(N-4-picolinio)ethoxycarbonyl-geschützten Aminoderivaten und kinetische Untersuchungen zur basisch induzierten Aminosäurefreisetzung

2-Bromoethoxycarbonyl modified amino acids were reacted with pyridine, 4-picoline and poly(4-vinylpyridine) to yield the corresponding 2-(N-pyridinio)ethoxycarbonyl derivatives as water-soluble amino-protecting groups. The kinetics and activation energies of basicly induced cleavage of the amino acids were investigated by ¹H NMR spectroscopy in a D₂O/NaOD medium. The polymeric salts were found to be more reactive than the low molecular weight pyridinium bromides because of electrostatic polymeric effects. Additionally, the kinetic measurements confirmed a E1cB mechanism for the cleavage of the urethane function. The formation of peptide bonds was performed in the case of poly[2-(N-4-vinylpyridinioethoxycarbonyl)]-protected amino acids in aqueous medium by water-soluble carbodiimides.     

Chondroitin sulfate A released from platelets blocks RANTES presentation on cell surfaces and RANTES-dependent firm adhesion of leukocytes

The sequestration of chemokines on the surface of microvascular endothelium is an early event in the selective recruitment of leukocytes. The sequestration and presentation of chemokines must be tightly controlled to confine the extravasation of leukocytes and to prevent uncontrolled inflammation. We investigated whether soluble molecules released under physiological conditions could control chemokine immobilization on cell surfaces and function as regulatory chemokine binding molecules. We determined that human serum contains a molecule that suppresses RANTES (CCL5) binding to endothelial cells, PBMC and CHO cells. Using platelet-rich and platelet-free plasma, serum from patients with thrombocytopenia, and purified platelets, we identified platelets as the source of the chemokine-binding molecule and further identified it as chondroitin sulfate A. In contrast to platelet-derived fully-sulfated chondroitin sulfate A, low-sulfated chondroitin sulfate A present in plasma was almost inactive. Under physiological flow conditions chondroitin sulfate A was found to block RANTES-mediated firm adhesion of monocytes to endothelial cells. It also prevented RANTES-mediated influx of calcium in CCR5-transfected CHO cells while internalization of CCR5 was only marginally reduced. Taken together, chondroitin sulfate A released from platelets appears to act as an important regulatory molecule for cellular responses to chemokines.     

Protective effects of PJ34, a novel, potent inhibitor of poly(ADP-ribose) polymerase (PARP) in in vitro and in vivo models of stroke

Focal cerebral ischemia activates the nuclear protein poly(ADP-ribose) polymerase (PARP) by single DNA strand breaks which leads to energy depletion and cell necrosis. Deletion or inhibition of PARP protects against ischemic brain injury. Here we examined the neuroprotective effect of PJ34, a novel potent inhibitor of PARP in vitro and in vivo. Serum-free primary neuronal cultures derived from rat cortex (E15-17) and kept in culture for 10 days were exposed to oxygen glucose deprivation (OGD) in vitro. Neuronal injury was quantified by LDH release after 24 h. Pretreatment with 30-1000 nM PJ34 significantly protected from OGD-induced cell injury in a dose-dependent manner. For in vivo experiments SV/129 mice were treated with PJ34 (50 microg) by intraperitoneal injection 2 h before 1 h middle cerebral artery occlusion (MCAo) and again 6 h later. Twenty-three h after reperfusion ischemic injury was significantly decreased compared to vehicle-treated controls (infarct volume reduction of 40%, p<0.05). Similarly, in a rat model of MCAo (2 h occlusion followed by up to 22 h reperfusion), PJ34 administration (10 mg/kg i.v.) significantly reduced infarct size, and the effect of the drug was maintained even if it was given as late as 10 min prior to reperfusion time. PJ34 significantly protected in a 4 h, but not in a 24 h permanent occlusion model. In conclusion, PJ34, a novel, potent inhibitor of PARP exerts massive neuroprotective agents, with a significant therapeutic window of opportunity. The present work strengthens the concept that pharmacological PARP inhibition may be a suitable approach for the treatment of acute stroke in man.     

Correlation of pathogenicity and gene constellation of an influenza a virus (fowl plague) I. Exchange of a single gene

Recombinants of fowl plague virus (FPV) with other influenza A prototype strains of human and animal origin in which only a single gene (RNA segment) is not derived from FPV were tested for their pathogenicity in chickens. Most of these recombinants had a lowered pathogenicity, while some were completely apathogenic. The apathogenic recombinants induced high titers of antibodies against the surface components of FPV in the infected chickens which were protected against a challenge infection with wild type FPV. Loss of pathogenicity depended on the gene which was exchanged as well as on the influenza A strain of which the foreign gene was derived, but no specific gene constellation could be detected for apathogenic recombinants. There is no clear correlation between growth rate and pathogenicity, indicating that other factors such as organ tropism might also play an important role in pathogenicity of influenza viruses.     

First confirmed case with paternal uniparental disomy of chromosome 16

The existence of paternal uniparental disomy of chromosome 16 [upd(16)pat] has previously been suspected but has not been proven. We report prenatal detection and follow-up of isodisomic upd(16)pat in a child with minimal defects but otherwise normal development. Our results indicate that isodisomic upd(16)pat is associated with a normal outcome if no recessive mutation is reduced to homozygosity.     

Melanotic Neuroectodermal Tumor of Infancy Occurring in the Left Thigh of a 6-Month-Old Female Infant

We report an exceptional case of melanotic neuro-ectodermal tumor of infancy (MNTI) occurring in the soft tissue of the left thigh of a 6-month-old female infant. The tumor consisted mainly of small round cells (neuroblasts) arranged in cords and nests that were separated by broad fibrovascular areas. In addition, there were a few medium-sized tumor cells containing melanin pigment (melano-cytic cells) that in electron microscopy contained melanosomes as well as tonofilaments. Both tumor cell types immunostained for neuron-specific enolase (NSE) and vimentin, and the melanocytic cells reacted additionally with the antikeratin antibody KL1. Within the tumor stroma, neurofilament- and S-100-protein-positive neural cells and vimentin- and desmin-positive myofibroblasts were seen. Although densecore granules were demonstrated ultrastructurally in some neuroblasts, no immunostaining for chromogranin A, Leu-7, serotonin, or regulatory peptides was found. MNTI located in an extremity can be confused with malignant small round and blue cell tumors of childhood. The distinction between MNTI and these tumors is of clinical significance because MNTI, in most cases, is a benign tumor that, in contrast to the latter, can be cured by complete excision. The presence of a biphasic cell population with neuroblasts and melanocytic cells must be considered the main diagnostic feature of MNTI.     

Epithelioid sarcoma in children and adolescents

Summary Six cases of epithelioid sarcoma were studied by conventional light microscopy and immunohistochemistry. The six cases account for 1.4% of the 417 cases of soft tissue sarcoma collected at the Paediatric Tumor Registry, Kiel. The average age of the five male and one female patient was 10.8 years (median: 13 years). Particular clinical findings included the location of the tumours; three were found in the pelvis, two in the head and neck, and one in the hand. Four patients are living without disease, and one patient died of disease three years after diagnosis.Histologically, four of the six tumours revealed multinucleated giant cells. Immunohistochemically using a panel of mono- and polyclonal antibodies all cases stained positively for vimentin, cytokeratin, epithelial membrane antigen (EMA), and human milk fat globulin (HMFG-2). Five cases were positive for neuron specific enolase (NSE), and three stained positively for protein S-100. A positive reaction for alpha-1-antichymotrypsin was noted in two cases. These immunohistochemical findings attest to the multidirectional differentiating capabilities of epithelioid sarcoma and support the concept of derivation from a multipotent mesenchymal stem cell.This study was supported in part by a grant from the Bundesminister für Arbeit und Sozialordnung and the Deutsche Forschungsgemeinschaft (Schm 613/1-1)     

Organization and expression of genes involved in the production of the K88ab antigen

Escherichia coli K-12 minicells were used to study the expression of the genes located on plasmid pFM205, which contains the genetic determinant of the K88ab antigen. Plasmid pFM205 is composed of a 4,3-megadalton large deoxyribonucleic acid fragment derived from the wild-type K88ab plasmid pRI8801 (51 megadaltons) and the cloning vehicle pBR322. The K88ab deoxyribonucleic acid of pFM205 appeared to express six polypeptides with apparent molecular masses of 81, 30, 29, 27, 26, and 17 kilodaltons, respectively. These polypeptides account for approximately 85% of the coding capacity of the cloned deoxyribonucleic acid. The 26-kilodalton polypeptide was found to react with specific anti-K88ab antibodies and therefore represents the K88ab subunit. The K88ab subunit and at least two other polypeptides (81 and 17 kilodaltons) were translated into precursors which were about 2 kilodaltons larger than the mature proteins. Plasmid pFM205 was used to construct deletion mutants. By analyzing these mutants in minicells the genes of the six polypeptides could be located on the physical map of pFM205. It appeared that deletion of the gene of the 81-kilodalton polypeptide resulted in an altered conformation of the K88ab antigen.