SNAP-25 deficit and hippocampal connectivity in schizophrenia

Regional abnormalities of brain connectivity may be an important substrate for the expression of schizophrenia, a severe form of mental illness. Brain imaging and postmortem morphometric studies indicate hippocampal structure is abnormal in schizophrenia. To study molecular components of hippocampal connectivity the presynaptic proteins SNAP-25 and synaptophysin were assayed in postmortem samples. Immunocytochemical studies indicated reduced SNAP-25 immunoreactivity in schizophrenia compared to controls, particularly in the terminal fields of entorhinal cortex projections. Although there were no overall changes in synaptophysin immunoreactivity, in the granule cell layer of the dentate gyrus synaptophysin immunoreactivity was increased in schizophrenia. These results indicate that disconnection of a subset of hippocampal circuitry from the entorhinal cortex, as well as intrinsic changes in hippocampal connectivity, may contribute to the mechanism of illness in schizophrenia.      

Manipulation of liver regeneration with macrophages to influence the hepatic progenitor cell niche

Insufficient regeneration of the adult liver is believed to cause failure to recover from severe liver disease. An undifferentiated cell population with stem-cell-like qualities known as hepatic progenitor cells (HPCs) is hypothesised to have a central role in regeneration of the adult liver during massive or chronic liver disease. Stem cells in other organ systems are believed to reside in a specialised microenvironment or niche that supports their maintenance and function. The existence of a hepatic stem cell niche might provide a means of therapeutically manipulating endogenous HPCs in vivo as a regenerative therapy.To investigate the physiological potential of HPCs to regenerate the mammalian liver, we have established a novel model of hepatocellular injury and HPC activation using genetic manipulation of hepatocytes. After hepatocyte senescence and death in this model (AhCre Mdm2^flox), HPCs expand and bring about the complete regeneration of the liver parenchyma.We demonstrate that a stereotypical niche, consisting partly of macrophages, exists in both animal models and correlating human disease. Using cell tracking, we show active recruitment of extrahepatic macrophages into this niche during injury. In health, intravenous injection of macrophages results in macrophage engraftment to the liver niche, with subsequent HPC activation and changes to liver structure and function.Within the niche, macrophages use paracrine signalling to control both HPC proliferation and cell fate via TWEAK (tumour-necrosis-factor-like weak inducer of apoptosis) and the Wnt signalling pathway, respectively. After hepatocellular injury, macrophages ingest hepatocyte debris, and release Wnt which promotes HPC differentiation into hepatocytes. TWEAK is vital for HPC proliferation in the AhCre Mdm2^flox model of regeneration. Here, the absence of TWEAK signalling results in liver failure and mortality.This work has demonstrated for the first time the ability of a solid organ to fully regenerate in the adult mammal from progenitor cells, and additionally highlights mechanisms by which this process can be modulated by either small molecule or cell therapy.FundingUniversity of Edinburgh.     

Gene expression changes linked to antimicrobial resistance, oxidative stress, iron depletion and retained motility are observed when Burkholderia cenocepacia grows in cystic fibrosis sputum

Background

Effective prophylaxis and treatment for infections caused by biological threat agents (BTA) rely upon early diagnosis and rapid initiation of therapy. Most methods for identifying pathogens in body fluids and tissues require that the pathogen proliferate to detectable and dangerous levels, thereby delaying diagnosis and treatment, especially during the prelatent stages when symptoms for most BTA are indistinguishable flu-like signs.

Methods

To detect exposures to the various pathogens more rapidly, especially during these early stages, we evaluated a suite of host responses to biological threat agents using global gene expression profiling on complementary DNA arrays.

Results

We found that certain gene expression patterns were unique to each pathogen and that other gene changes occurred in response to multiple agents, perhaps relating to the eventual course of illness. Nonhuman primates were exposed to some pathogens and the in vitro and in vivo findings were compared. We found major gene expression changes at the earliest times tested post exposure to aerosolized B. anthracis spores and 30 min post exposure to a bacterial toxin.

Conclusion

Host gene expression patterns have the potential to serve as diagnostic markers or predict the course of impending illness and may lead to new stage-appropriate therapeutic strategies to ameliorate the devastating effects of exposure to biothreat agents.     

Function of wild-type or mutant Rac2 and Rap1a GTPases in differentiated HL60 cell NADPH oxidase activation

Studies of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation in a cell-free system showed that the low molecular-weight guanosine triphosphatase (GTPase) Rac was required, and that Rap1a may participate in activation of the catalytic complex. Full-length posttranslationally modified Rac2 was active, whereas only the 1-166 truncated form of Rap1a was functional in the cell-free system, and thus, clarification of the function of Rap1a and Rac2 in intact human phagocytes is needed to provide further insight into their roles as signal transducers from plasma membrane receptors. In the present studies, oligonucleotide-directed mutagenesis was used to introduce a series of mutations into human rap1a or rac2 in the mammalian expression vector pSR alpha neo. HL60 cells transfected with wild-type or mutated rac2 or rap1a cDNA constructs and control HL60 cells transfected with the pSR alpha neo vector containing no inserted cDNA were selected in G418-containing media, then subclones were isolated. Compared with the parent HL60 cells, each of the stable transfected cell lines differentiated similarly into neutrophil-like cells and expressed comparable levels of NADPH oxidase components p47- phox, p67-phox and gp91-phox. The differentiated vector control cell line produced O2. in response to receptor stimulation at rates that were not significantly different from parent HL60 cells. O2-. production by differentiated cell lines expressing mutated N17 Rap1a or N17 Rac2 dominant-negative proteins was inhibited, whereas O2-. production by the subline overexpressing wild-type Rap1a was increased by fourfold. O2-. production by the differentiated cell line expressing GTPase-defective V12 Rap1a was also significantly inhibited, a finding that is consistent with a requirement for cycling between guanosine diphosphate- and GTP-bound forms of Rap1a for continuous NADPH oxidase activation in intact neutrophils. A model is proposed in which Rac2 mediates assembly of the p47 and p67 oxidase components on the cytosolic face of the plasma membrane via cytoskeletal reorganization, whereas Rap1a functions downstream as the final activation switch involving direct physical interaction with the transmembrane flavocytochrome component of the NADPH oxidase.     

The behavior of epididymis, processus vaginalis and testicular descent in cryptorchid boys treated with buserelin

This randomized double-blind placebo-controlled study was initiated to analyze the behavior of epididymis, processus vaginalis and testicular descent in cryptorchid boys treated with a low dose (20 g) of a luteinizing hormone-releasing hormone analogue (Buserelin), administered daily, as a nasal spray, for a short period (28 days). Fifty-nine true cryptorchid boys were randomly assigned to 3 groups: buserelin, treatment [22], surgical treatment [18] or placebo control group [19]. The 3 groups of patients were similar before treatment in regard to testicular position, chronological and bone age, height and weight, luteinizing hormone, follicle-stimulating hormone, testosterone, penile size and the volume of the contralateral descended testis. None of the patients had retractile testes. Buserelin significantly induced testicular descent compared to the boys treated with a placebo (P<0.01). A normal epididymis was found more often in boys with successful descent (P<0.003). A closed processus vaginalis was also more frequently observed in the group treated with buserelin than in surgically treated one (P<0.05). In conclusion, buserelin was capable of inducing testicular descent besides provoking further development of the epididymis and closing the processus vaginalis.     

Nitric oxide production during the early neonatal period in small-for-gestational-age infants

In a study of endogenous nitric oxide production in growth-retarded, very preterm newborns (<32 wk GA), urinary NOx/creatinine ratio and plasma guanosine 3',5'-cyclic monophosphate levels were determined during the early neonatal period. Newborns were divided into three groups: appropriate-for-gestational-age (AGA, n = 19), moderately small-for-gestational-age (SGA, n = 13) and severely SGA (n = 6) infants. Severely SGA infants showed significant higher values of nitric oxide derivatives during the first 24 h of life compared with the other groups. CONCLUSION: An increased NO production is found in SGA infants during the first 24 h after birth. This may reflect an increased intrauterine nitric oxide production in the feto-placental circulation found in cases with intrauterine growth retardation,