Produce: The Active News for You to Consume, November/December 2009.

Monthly news about the Iowans Fit for Life initiative for promoting physical activity and nutrition.

Produce: The Active News for You to Consume, January 2010.

Monthly news about the Iowans Fit for Life initiative for promoting physical activity and nutrition.

Produce: The Active News for You to Consume, February 2010.

Monthly news about the Iowans Fit for Life initiative for promoting physical activity and nutrition.

HCFC1 is a common component of active human CpG-island promoters and coincides with ZNF143, THAP11, YY1, and GABP transcription factor occupancy.

In human transcriptional regulation, DNA-sequence-specific factors can associate with intermediaries that orchestrate interactions with a diverse set of chromatin-modifying enzymes. One such intermediary is HCFC1 (also known as HCF-1). HCFC1, first identified in herpes simplex virus transcription, has a poorly defined role in cellular transcriptional regulation. We show here that, in HeLa cells, HCFC1 is observed bound to 5400 generally active CpG-island promoters. Examination of the DNA sequences underlying the HCFC1-binding sites revealed three sequence motifs associated with the binding of (1) ZNF143 and THAP11 (also known as Ronin), (2) GABP, and (3) YY1 sequence-specific transcription factors. Subsequent analysis revealed colocalization of HCFC1 with these four transcription factors at ∼90% of the 5400 HCFC1-bound promoters. These studies suggest that a relatively small number of transcription factors play a major role in HeLa-cell transcriptional regulation in association with HCFC1.

Restoration of anti-tetanus toxoid responses in patients initiating highly active antiretroviral therapy with or without a boost immunization: an INITIO substudy.

INITIO is an open-labelled randomized trial evaluating first-line therapeutic strategies for human immunodeficiency virus-1 (HIV-1) infection. In an immunology substudy a tetanus toxoid booster (TTB) immunization was planned for 24 weeks after initiation of highly active antiretroviral therapy (HAART). All patients had received tetanus toxoid immunization in childhood. Generation of proliferative responses to tetanus toxoid was compared in two groups of patients, those receiving a protease inhibitor (PI)-sparing regimen (n = 21) and those receiving a PI-containing (n = 54) regimen. Fifty-two participants received a TTB immunization [PI-sparing (n = 15), PI-containing (n = 37)] and 23 participants did not [PI-sparing (n = 6) or PI-containing (n = 17)]. Cellular responses to tetanus antigen were monitored by lymphoproliferation at time of immunization and every 24 weeks to week 156. Proportions with a positive response (defined as stimulation index > or = 3 and Delta counts per minute > or = 3000) were compared at weeks 96 and 156. All analyses were intent-to-treat. Fifty-two participants had a TTB immunization at median 25 weeks; 23 patients did not. At weeks 96 and 156 there was no evidence of a difference in tetanus-specific responses, between those with or without TTB immunization (P = 0.2, P = 0.4). There was no difference in the proportion with response between those with PI-sparing or PI-containing regimens at both time-points (P = 0.8, P = 0.7). The proliferative response to tetanus toxoid was unaffected by initial HAART regimen. Anti-tetanus responses appear to reconstitute eventually in most patients over 156 weeks when treated successfully with HAART, irrespective of whether or not a TTB immunization has been administered.

Human alveolar macrophages infected by virulent bacteria expressing SipB are a major source of active interleukin-18.

Recent publications have demonstrated that the protease caspase-1 is responsible for the processing of pro-interleukin 18 (IL-18) into the active form. Studies on cell lines and murine macrophages have shown that the bacterial invasion factor SipB activates caspase-1, triggering cell death. Thus, we investigated the role of SipB in the activation and release of IL-18 in human alveolar macrophages (AM), which are the first line of defense against inhaled pathogens. Under steady-state conditions, AM are a more important source of IL-18 than are dendritic cells (DC) and monocytes. Cytokine production by AM and DC was compared after both types of cells had been infected with a virulent strain of Salmonella enterica serovar Typhimurium and an isogenic sipB mutant, which were used as an infection model. Infection with virulent Salmonella led to marked cell death with features of apoptosis while both intracellular activation and release of IL-18 were demonstrated. In contrast, the sipB mutant did not induce such cell death or the release of active IL-18. The specific caspase-1 inhibitor Ac-YVAD-CMK blocked the early IL-18 release in AM infected with the virulent strain. However, the type of Salmonella infection did not differentially regulate IL-18 gene expression. We concluded that the bacterial virulence factor SipB plays an essential posttranslational role in the intracellular activation of IL-18 and the release of the cytokine in human AM.

Regular wave propagation out of noise in chemical active media

A pacemaker, regularly emitting chemical waves, is created out of noise when an excitable photosensitive Belousov-Zhabotinsky medium, strictly unable to autonomously initiate autowaves, is forced with a spatiotemporal patterned random illumination. These experimental observations are also reproduced numerically by using a set of reaction-diffusion equations for an activator-inhibitor model, and further analytically interpreted in terms of genuine coupling effects arising from parametric fluctuations. Within the same framework we also address situations of noise-sustained propagation in subexcitable media.

Transolecranon anterior fracture dislocation.

Between January 1996 and July 2003, 93 consecutive patients operated on with a diagnosis of olecranon fractures were identified from our trauma unit files. Fourteen transolecranon fracture-dislocations were found after a retrospective X-radiographic evaluation. Eight patients were women and six were men, with a mean age of 54 years. There were 4 noncomminuted olecranon fractures, treated with K-wires and single tension-band wiring. The remaining 10 fractures were complex fractures, treated in 3 cases with multiple K-wires and single tension-band wiring, in 2 by use of one-third tubular plates, in 1 with a 3.5-mm dynamic compression plate, and in the remaining 4 with 3.5-mm reconstruction plates. Ligament repair was not performed in any case. Three patients needed reoperation because of early failure of primary fixation. Patients were reviewed at a mean follow-up of 3.6 years. Two reported difficulties in daily activities, none with any symptoms of elbow instability. According to the Broberg and Morrey score, 4 patients had excellent results, 6 had good results, 2 had fair results, and 2 had poor results. Four patients showed signs of degenerative arthritis on the radiographs obtained at follow-up. We conclude that transolecranon fracture-dislocation is an underreported and misdiagnosed injury. Various fixation techniques can restore the anatomic relationships and contour of the trochlear notch; the imperative goal is to obtain a good stable primary fixation and allow early active mobilization.

Tobramycin exposure from active calcium sulfate bone graft substitute.

BACKGROUND: Bone graft substitute such as calcium sulfate are frequently used as carrier material for local antimicrobial therapy in orthopedic surgery. This study aimed to assess the systemic absorption and disposition of tobramycin in patients treated with a tobramycin-laden bone graft substitute (Osteoset® T). METHODS: Nine blood samples were taken from 12 patients over 10 days after Osteoset® T surgical implantation. Tobramycin concentration was measured by fluorescence polarization. Population pharmacokinetic analysis was performed using NONMEM to assess the average value and variability (CV) of pharmacokinetic parameters. Bioavailability (F) was assessed by equating clearance (CL) with creatinine clearance (Cockcroft CLCr). Based on the final model, simulations with various doses and renal function levels were performed. (ClinicalTrials.gov number, NCT01938417). RESULTS: The patients were 52 +/- 20 years old, their mean body weight was 73 +/- 17 kg and their mean CLCr was 119 +/- 55 mL/min. Either 10 g or 20 g Osteoset® T with 4% tobramycin sulfate was implanted in various sites. Concentration profiles remained low and consistent with absorption rate-limited first-order release, while showing important variability. With CL equated to CLCr, mean absorption rate constant (ka) was 0.06 h-1, F was 63% or 32% (CV 74%) for 10 and 20 g Osteoset® T respectively, and volume of distribution (V) was 16.6 L (CV 89%). Simulations predicted sustained high, potentially toxic concentrations with 10 g, 30 g and 50 g Osteoset® T for CLCr values below 10, 20 and 30 mL/min, respectively. CONCLUSIONS: Osteoset® T does not raise toxicity concerns in subjects without significant renal failure. The risk/benefit ratio might turn unfavorable in case of severe renal failure, even after standard dose implantation.

Neurogenic subventricular zone stem/progenitor cells are notch1-dependent in their active but not quiescent state.

The adult mammalian forebrain contains neural stem/progenitor cells (NSCs) that generate neurons throughout life. As in other somatic stem cell systems, NSCs are proposed to be predominantly quiescent and proliferate only sporadically to produce more committed progeny. However, quiescence has recently been shown not to be an essential criterion for stem cells. It is not known whether NSCs show differences in molecular dependence based on their proliferation state. The subventricular zone (SVZ) of the adult mouse brain has a remarkable capacity for repair by activation of NSCs. The molecular interplay controlling adult NSCs during neurogenesis or regeneration is not clear but resolving these interactions is critical in order to understand brain homeostasis and repair. Using conditional genetics and fate mapping, we show that Notch signaling is essential for neurogenesis in the SVZ. By mosaic analysis, we uncovered a surprising difference in Notch dependence between active neurogenic and regenerative NSCs. While both active and regenerative NSCs depend upon canonical Notch signaling, Notch1-deletion results in a selective loss of active NSCs (aNSCs). In sharp contrast, quiescent NSCs (qNSCs) remain after Notch1 ablation until induced during regeneration or aging, whereupon they become Notch1-dependent and fail to fully reinstate neurogenesis. Our results suggest that Notch1 is a key component of the adult SVZ niche, promoting maintenance of aNSCs, and that this function is compensated in qNSCs. Therefore, we confirm the importance of Notch signaling for maintaining NSCs and neurogenesis in the adult SVZ and reveal that NSCs display a selective reliance on Notch1 that may be dictated by mitotic state.

Towards a resolution of conflicting models of illusory contour processing in humans.

Despite myriad studies, neurophysiologic mechanisms mediating illusory contour (IC) sensitivity remain controversial. Among the competing models one favors feed-forward effects within lower-tier cortices (V1/V2). Another situates IC sensitivity first within higher-tier cortices, principally lateral-occipital cortices (LOC), with later feedback effects in V1/V2. Still others postulate that LOC are sensitive to salient regions demarcated by the inducing stimuli, whereas V1/V2 effects specifically support IC sensitivity. We resolved these discordances by using misaligned line gratings, oriented either horizontally or vertically, to induce ICs. Line orientation provides an established assay of V1/V2 modulations independently of IC presence, and gratings lack salient regions. Electrical neuroimaging analyses of visual evoked potentials (VEPs) disambiguated the relative timing and localization of IC sensitivity with respect to that for grating orientation. Millisecond-by-millisecond analyses of VEPs and distributed source estimations revealed a main effect of grating orientation beginning at 65 ms post-stimulus onset within the calcarine sulcus that was followed by a main effect of IC presence beginning at 85 ms post-stimulus onset within the LOC. There was no evidence for differential processing of ICs as a function of the orientation of the grating. These results support models wherein IC sensitivity occurs first within the LOC.

Estimating dormant and active hematopoietic stem cell kinetics through extensive modeling of bromodeoxyuridine label-retaining cell dynamics.

Bone marrow hematopoietic stem cells (HSCs) are responsible for both lifelong daily maintenance of all blood cells and for repair after cell loss. Until recently the cellular mechanisms by which HSCs accomplish these two very different tasks remained an open question. Biological evidence has now been found for the existence of two related mouse HSC populations. First, a dormant HSC (d-HSC) population which harbors the highest self-renewal potential of all blood cells but is only induced into active self-renewal in response to hematopoietic stress. And second, an active HSC (a-HSC) subset that by and large produces the progenitors and mature cells required for maintenance of day-to-day hematopoiesis. Here we present computational analyses further supporting the d-HSC concept through extensive modeling of experimental DNA label-retaining cell (LRC) data. Our conclusion that the presence of a slowly dividing subpopulation of HSCs is the most likely explanation (amongst the various possible causes including stochastic cellular variation) of the observed long term Bromodeoxyuridine (BrdU) retention, is confirmed by the deterministic and stochastic models presented here. Moreover, modeling both HSC BrdU uptake and dilution in three stages and careful treatment of the BrdU detection sensitivity permitted improved estimates of HSC turnover rates. This analysis predicts that d-HSCs cycle about once every 149-193 days and a-HSCs about once every 28-36 days. We further predict that, using LRC assays, a 75%-92.5% purification of d-HSCs can be achieved after 59-130 days of chase. Interestingly, the d-HSC proportion is now estimated to be around 30-45% of total HSCs - more than twice that of our previous estimate.