The evolving art of hematopoietic stem cell transplantation: translational research in post-transplant immune reconstitution and immunosuppression

Immunologic Research - Allogeneic hematopoietic stem cell transplantation (SCT) offers the best chance for cure and/or long-term survival for a broad range of diseases, including many high-risk...     

PERCEPTUALLY BASED FALSE RECOGNITION OF NOVEL OBJECTS IN AMNESIA: EFFECTS OF CATEGORY SIZE AND SIMILARITY TO CATEGORY PROTOTYPES

Previous research suggests that amnesics may show impaired semantically based false recognition under conditions where control participants show high levels of gist-based errors, but little or no impairment when controls show less robust false recognition. Using abstract novel objects, we examined perceptually based false recognition in amnesics under conditions designed to induce differing levels of false recognition in controls. Whereas amnesics showed significantly impaired false recognition for category prototypes, and numerically impaired false recognition when many perceptually similar exemplars were studied-conditions where controls showed high rates of illusory recognition-amnesics and controls showed lower, and comparable, levels of false recognition when few related exemplars were studied, or lures were at a far transformational distance from the prototype. Although amnesics may be able to extract some information regarding the perceptual “gist” of studied items, they appear to do so less efficiently than controls.     

Latent learning of spatial information is impaired in middle‐aged rats

The present study determined if the middle age related impairment that occurs with nonspatial latent learning also occurs in spatial latent learning. Thirty young (3‐months‐old) and 30 middle‐aged (12‐months‐old) male Sprague–Dawley rats were given either pre‐exposure to spatial cues surrounding a Barnes maze (SpatialPX), or pre‐exposure to just the maze (MazePX). They were then given 10 training trials in which they had to find a hidden escape box while experiencing an aversive environment produced by bright lights and wind. Results showed that young rats given the SpatialPX condition demonstrated faster escape latencies and fewer errors than young rats given the MazePX condition. However, middle‐aged rats given the SpatialPX condition did not show this improved performance. These findings indicate that the middle age learning deficit is not task specific, but rather is a general impairment in latent learning, possibly due to the early degeneration of the entorhinal cortex. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 309–315, 2013     

Intestinal Microbiota Containing Barnesiella Species Cures Vancomycin-Resistant Enterococcus faecium Colonization

Bacteria causing infections in hospitalized patients are increasingly antibiotic resistant. Classical infection control practices are only partially effective at preventing spread of antibiotic-resistant bacteria within hospitals. Because the density of intestinal colonization by the highly antibiotic-resistant bacterium vancomycin-resistant Enterococcus (VRE) can exceed 10⁹ organisms per gram of feces, even optimally implemented hygiene protocols often fail. Decreasing the density of intestinal colonization, therefore, represents an important approach to limit VRE transmission. We demonstrate that reintroduction of a diverse intestinal microbiota to densely VRE-colonized mice eliminates VRE from the intestinal tract. While oxygen-tolerant members of the microbiota are ineffective at eliminating VRE, administration of obligate anaerobic commensal bacteria to mice results in a billionfold reduction in the density of intestinal VRE colonization. 16S rRNA gene sequence analysis of intestinal bacterial populations isolated from mice that cleared VRE following microbiota reconstitution revealed that recolonization with a microbiota that contains Barnesiella correlates with VRE elimination. Characterization of the fecal microbiota of patients undergoing allogeneic hematopoietic stem cell transplantation demonstrated that intestinal colonization with Barnesiella confers resistance to intestinal domination and bloodstream infection with VRE. Our studies indicate that obligate anaerobic bacteria belonging to the Barnesiella genus enable clearance of intestinal VRE colonization and may provide novel approaches to prevent the spread of highly antibiotic-resistant bacteria.     

KRAS (but not BRAF) mutations in ovarian serous borderline tumour are associated with recurrent low‐grade serous carcinoma

BRAF and KRAS mutations in ovarian serous borderline tumours (OSBTs) and ovarian low‐grade serous carcinomas (LGSCs) have been previously described. However, whether those OSBTs would progress to LGSCs or whether those LGSCs were developed from OSBT precursors in previous studies is unknown. Therefore, we assessed KRAS and BRAF mutations in tumour samples from 23 recurrent LGSC patients with a known initial diagnosis of OSBT. Paraffin blocks from both OSBT and LGSC samples were available for five patients, and either OSBTs or LGSCs were available for another 18 patients. Tumour cells from paraffin‐embedded tissues were dissected out for mutation analysis by conventional polymerase chain reaction (PCR) and Sanger sequencing. Tumours that appeared to have wild‐type KRAS by conventional PCR–Sanger sequencing were further analysed by full COLD (co‐amplification at lower denaturation temperature)‐PCR and deep sequencing. Full COLD‐PCR was able to enrich the amplification of mutated alleles. Deep sequencing was performed with the Ion Torrent personal genome machine (PGM). By conventional PCR–Sanger sequencing, BRAF mutation was detected only in one patient and KRAS mutations were detected in ten patients. Full COLD‐PCR deep sequencing detected low‐abundance KRAS mutations in eight additional patients. Three of the five patients with both OSBT and LGSC samples available had the same KRAS mutations detected in both OSBT and LGSC samples. The remaining two patients had only KRAS mutations detected in their LGSC samples. For patients with either OSBT or LGSC samples available, KRAS mutations were detected in seven OSBT samples and six LGSC samples. Surprisingly, patients with the KRAS G12V mutation have shorter survival times. In summary, KRAS mutations are very common in recurrent LGSC, while BRAF mutations are rare. The findings indicate that recurrent LGSC can arise from proliferation of OSBT tumour cells with or without detectable KRAS mutations. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Single-channel biophysical and pharmacological characterizations of native human large-conductance calcium-activated potassium channels in freshly isolated detrusor smooth muscle cells

Recent studies have demonstrated the importance of large-conductance Ca²⁺-activated K⁺ (BK) channels in detrusor smooth muscle (DSM) function in vitro and in vivo. However, in-depth characterization of human native DSM single BK channels has not yet been provided. Here, we conducted single-channel recordings from excised patches from native human DSM cells. Inside-out and outside-out recordings in high K⁺ symmetrical solution (containing 140 mM KCl and ~300 nM free Ca²⁺) showed single-channel conductance of 215–220 pS, half-maximum constant for activation of ~+75 to +80 mV, and low probability of opening (P _o) at +20 mV that increased ~10-fold at +40 mV and ~60-fold at +60 mV. Using the inside-out configuration at +30 mV, reduction of intracellular [Ca²⁺] from ~300 nM to Ca²⁺-free decreased the P _o by ~85 %, whereas elevation to ~800 nM increased P _o by ~50-fold. The BK channel activator NS1619 (10 μM) enhanced the P _o by ~10-fold at +30 mV; subsequent application of the selective BK channel inhibitor paxilline (500 nM) blocked the activity. Changes in intracellular [Ca²⁺] or the addition of NS1619 did not significantly alter the current amplitude or single-channel conductance. This is the first report to provide biophysical and pharmacological profiles of native human DSM single BK channels highlighting their importance in regulating human DSM excitability.