Crystal Structure and Molecular Conformation of the Cyclic Hexapeptide cyclo-(Gly-Aib-Gly)2

We have synthesized and crystallized the cyclic peptide (Gly-Aib-Gly) ₂. Its structure has been determined by conventional X-ray diffracti on methods. In the crystal it adopts a conformation with one β-turn (type I) and its mirror image at the other side of the ring. All conformation al angles are similar to those reported for these amino acid residues. In particular the Aib residue has a conformation intermediate between α- and 3₁₀-helical conformations. The ring is an adequate model for the β-turn conformation. A molecule of formic acid is found in the crystal which shows a very short hydrogen bond with one of the glycine carbonyl groups.     

Sprouty1 induces a senescence-associated secretory phenotype by regulating NFκB activity: implications for tumorigenesis

Genes of the Sprouty family (Spry1–4) are feedback inhibitors of receptor tyrosine kinase (RTK) signaling. As such, they restrain proliferation of many cell types and have been proposed as tumor-suppressor genes. Although their most widely accepted target is the Extracellular-regulated kinases (ERK) pathway, the mechanisms by which Spry proteins inhibit RTK signaling are poorly understood. In the present work, we describe a novel mechanism by which Spry1 restricts proliferation, independently of the ERK pathway. In vivo analysis of thyroid glands from Spry1 knockout mice reveals that Spry1 induces a senescence-associated secretory phenotype via activation of the NFκB pathway. Consistently, thyroids from Spry1 knockout mice are bigger and exhibit decreased markers of senescence including Ki67 labeling and senescence-associated β-galactosidase. Although such ‘escape'' from senescence is not sufficient to promote thyroid tumorigenesis in adult mice up to 5 months, the onset of Phosphatase and tensin homolog (Pten)-induced tumor formation is accelerated when Spry1 is concomitantly eliminated. Accordingly, we observe a reduction of SPRY1 levels in human thyroid malignancies when compared with non-tumoral tissue. We propose that Spry1 acts as a sensor of mitogenic activity that not only attenuates RTK signaling but also induces a cellular senescence response to avoid uncontrolled proliferation.     

Perilesional intrathecal administration of autologous bone marrow stromal cells achieves functional improvement in pigs with chronic paraplegia

Background aimsAt present, on the basis of the great number of preclinical studies and preliminary clinical trials in humans, bone marrow stromal cell (BMSC) transplantation offers promise in the treatment of paraplegia. Nevertheless, there is not enough experience in humans about the best candidates for this type of cell therapy or details about the best parameters or best route of administration.MethodsTwo adult paraplegic pigs with chronic paraplegia were treated only with perilesional intrathecal administration of 40 × 10⁶ autologous BMSC suspended in autologous plasma and followed for 1 year after cell transplantation.ResultsOur study showed clinical improvement, starting at 2 mo after BMSC administration and reaching stabilization at 10 mo. This was associated with recovery of previously abolished somatosensory-evoked potentials. At the end of the study, histological images suggested spinal cord regeneration.ConclusionsOur present findings suggest the possible utility of perilesional intrathecal administration of autologous BMSC in patients with chronic paraplegia.     

Charge heterogeneity of heat-labile enterotoxins from human enterotoxigenic Escherichia coli

Abstract We purified heat-labile enterotoxins (LThs) from YT3, H-10407 and YT240 strains isolated from human diarrheal patients. These LThs were immunologically identical to each other. The molecular weights of their A and B subunits were also the same by means of SDS-polyacrylamide gel electrophoresis. However, the ionic charges of the molecular surfaces of these LThs were different as shown by polyacrylamide gel isoelectric focusing. Though the p I points of B subunits of the LThs were identical to each other, the p I points of A subunits were found to be different. These data suggest that the ionic charge differences among A subunits cause differences in holo LThs in their charge, and that there is heterogeneity among A subunits produced by strains of human enterotoxigenic Escherichia coli .     

Connections of the cerebellar grains with neuroglial and vascular structures. Interpretation of the grain as a modified neuroglial element.

Using the slightly modified method of Golgi-Valenzuela we studied the cerebellum of 2-week-old dogs. We noted a close anatomical relationship between the cerebellar grains and blood vessels. We found this similar to those of other neuroglial elements. We have described contacts between dendrites of the grains, similar to those of known synaptic junctions. We consider the cerebellar grains as a possible evolutionary form of astrocytes. In this respect, the author would like to interpret them as a possible basis for pathogenetic interpretation of neurological disorders such as ataxia-telangiectasia syndrome, an ontogenic bond between undifferentiated blood elements, astroglia, oligodendroglia and cerebellar grains.     

Late transplantation of allogeneic bone marrow stromal cells improves neurologic deficits subsequent to intracerebral hemorrhage

Background aimsStem cell therapy seems to be a promising therapeutic tool for treating central nervous system (CNS) injuries. Bone marrow stromal cell (BMSC) transplantation influences functional outcome subsequent to intracerebral hemorrhage (ICH), and enhances endogenous neurogenesis in acute condition studies. We investigated whether late administration of BMSC improves functional deficits subsequent to ICH.MethodsExperimental ICH was induced by stereotactic injection of 0.5 IU collagenase type IV in the striatum of adult female Wistar rats, and 2 months later intralesional administration of 5 × 10⁶ allogeneic BMSC from male donors rats in saline (n = 10), or saline only (n = 10), was performed. In the following 6 months, functional outcome was evaluated in each animal by rotarod, modified neurologic severity score (mNSS) and video-tracking box (VTB) tests. To study the behavior of BMSC after transplantation, in situ hybridization studies were performed, with double labeling of the chromosome Y-linked SrY-gene, and neuronal nuclei (NeuN) protein or gliofibrillary acidic protein (GFAP).ResultsThe assessment test revealed significant improvements in functional outcome for the BMSC-treated animals after 2 months of follow-up. Histologic results showed that functional outcome was associated with strong reactivation of endogenous neurogenesis. Furthermore, intralesional BMSC not only integrated in the injured tissue but also showed phenotypic expression of GFAP and NeuN.ConclusionsLate intracerebral transplantation of allogeneic BMSC induces functional recovery after ICH. The possibility of using this type of cell therapy to reverse the consequences of hemorrhagic stroke in humans should be considered.