Engraftment and lineage potential of adult hematopoietic stem and progenitor cells is compromised following short-term culture in the presence of an aryl hydrocarbon receptor antagonist

Hematopoietic stem cell gene therapy for HIV/AIDS is a promising alternative to lifelong antiretroviral therapy. One of the limitations of this approach is the number and quality of stem cells available for transplant following in vitro manipulations associated with stem cell isolation and genetic modification. The development of methods to increase the number of autologous, gene-modified stem cells available for transplantation would overcome this barrier. Hematopoietic stem and progenitor cells (HSPC) from adult growth factor-mobilized peripheral blood were cultured in the presence of an aryl hydrocarbon receptor antagonist (AhRA) previously shown to expand HSPC from umbilical cord blood. Qualitative and quantitative assessment of the hematopoietic potential of minimally cultured (MC-HSPC) or expanded HSPC (Exp-HSPC) was performed using an immunodeficient mouse model of transplantation. Our results demonstrate robust, multilineage engraftment of both MC-HSPC and Exp-HSPC although estimates of expansion based on stem cell phenotype were not supported by a corresponding increase in in vivo engrafting units. Bone marrow of animals transplanted with either MC-HSPC or Exp-HSPC contained secondary engrafting cells verifying the presence of primitive stem cells in both populations. However, the frequency of in vivo engrafting units among the more primitive CD34+/CD90+ HSPC population was significantly lower in Exp-HSPC compared with MC-HSPC. Exp-HSPC also produced fewer lymphoid progeny and more myeloid progeny than MC-HSPC. These results reveal that in vitro culture of adult HSPC in AhRA maintains but does not increase the number of in vivo engrafting cells and that HSPC expanded in vitro contain defects in lymphopoiesis as assessed in this model system. Further investigation is required before implementation of this approach in the clinical setting.

Alcam regulates long-term hematopoietic stem cell engraftment and self-renewal

Hematopoietic stem cells (HSCs) reside in a specialized bone marrow (BM) microenvironment that supports the maintenance and functional integrity of long-term (LT)-HSCs throughout postnatal life. The objective of this work is to study the role of activated leukocyte cell adhesion molecule (Alcam) in HSC differentiation and self-renewal using an Alcam-null (Alcam(-/-) ) mouse model. We show here that Alcam is differentially regulated in adult hematopoiesis and is highly expressed in LT-HSCs where its level progressively increases with age. Young adult Alcam(-/-) mice had normal homeostatic hematopoiesis and normal numbers of phenotypic HSCs. However, Alcam(-/-) HSCs had reduced long-term replating capacity in vitro and reduced long-term engraftment potential upon transplantation. We show that Alcam(-/-) BM contain a markedly lower frequency of long-term repopulating cells than wild type. Further, the long-term repopulating potential and engraftment efficiency of Alcam(-/-) LT-HSCs was greatly compromised despite a progressive increase in phenotypic LT-HSC numbers during long-term serial transplantation. In addition, an age-associated increase in phenotypic LT-HSC cellularity was observed in Alcam(-/-) mice. This increase was predominately within the CD150(hi) fraction and was accompanied by significantly reduced leukocyte output. Consistent with an aging-like phenotype, older Alcam(-/-) LT-HSCs display myeloid-biased repopulation activity upon transplantation. Finally, Alcam(-/-) LT-HSCs display premature elevation of age-associated gene expression, including Selp, Clu, Cdc42, and Foxo3. Together, this study indicates that Alcam regulates functional integrity and self-renewal of LT-HSCs.

Optimized processing of growth factor mobilized peripheral blood CD34+ products by counterflow centrifugal elutriation

Cell separation by counterflow centrifugal elutriation has been described for the preparation of monocytes for vaccine applications, but its use in other current good manufacturing practice (cGMP) operations has been limited. In this study, growth factor-mobilized peripheral blood progenitor cell products were collected from healthy donors and processed by elutriation using a commercial cell washing device. Fractions were collected for each product as per the manufacturer's instructions or using a modified protocol developed in our laboratory. Each fraction was analyzed for cell count, viability, and blood cell differential. Our data demonstrate that, using standard elutriation procedures, >99% of red blood cells and platelets were removed from apheresis products with high recoveries of total white blood cells and enrichment of CD34+ cells in two of five fractions. With modification of the basic protocol, we were able to collect all of the CD34+ cells in a single fraction. The CD34-enriched fractions were formulated, labeled with a ferromagnetic antibody to CD34, washed using the Elutra device, and transferred directly to a magnetic bead selection device for further purification. CD34+ cell purities from the column were extremely high (98.7 ± 0.9%), and yields were typical for the device (55.7 ± 12.3%). The processes were highly automated and closed from receipt of the apheresis product through formulation of target-enriched cell fractions. Thus, elutriation is a feasible method for the initial manipulations associated with primary blood cell therapy products and supports cGMP and current good tissue practice-compliant cell processing.

Latitudinal variation in top-down and bottom-up control of a salt marsh food web

The shrub Iva frutescens, which occupies the terrestrial border of U.S. Atlantic Coast salt marshes, supports a food web that varies strongly across latitude. We tested whether latitudinal variation in plant quality (higher at high latitudes), consumption by omnivores (a crab, present only at low latitudes), consumption by mesopredators (ladybugs, present at all latitudes), or the life history stage of an herbivorous beetle could explain continental-scale field patterns of herbivore density. In a mesocosm experiment, crabs exerted strong top-down control on herbivorous beetles, ladybugs exerted strong top-down control on aphids, and both predators benefited plants through trophic cascades. Latitude of plant origin had no effect on consumers. Herbivorous beetle density was greater if mesocosms were stocked with beetle adults rather than larvae, and aphid densities were reduced in the "adult beetle" treatment. Treatment combinations representing high and low latitudes produced patterns of herbivore density similar to those in the field. We conclude that latitudinal variation in plant quality is less important than latitudinal variation in top consumers and competition in mediating food web structure. Climate may also play a strong role in structuring high-latitude salt marshes by limiting the number of herbivore generations per growing season and causing high overwintering mortality.

Glucose addiction of TSC null cells is caused by failed mTORC1-dependent balancing of metabolic demand with supply

The mTORC1-signaling pathway integrates environmental conditions into distinct signals for cell growth by balancing anabolic and catabolic processes. Accordingly, energetic stress inhibits mTORC1 signaling predominantly through AMPK-dependent activation of TSC1/2. Thus, TSC1/2-/- cells are hypersensitive to glucose deprivation, and this has been linked to increased p53 translation and activation of apoptosis. Herein, we show that mTORC1 inhibition during glucose deprivation prevented not only the execution of death, but also induction of energetic stress. mTORC1 inhibition during glucose deprivation decreased AMPK activation and allowed ATP to remain high, which was both necessary and sufficient for protection. This effect was not due to increased catabolic activities such as autophagy, but rather exclusively due to decreased anabolic processes, reducing energy consumption. Specifically, TSC1/2-/- cells become highly dependent on glutamate dehydrogenase-dependent glutamine metabolism via the TCA cycle for survival. Therefore, mTORC1 inhibition during energetic stress is primarily to balance metabolic demand with supply.

Does combined multichannel intraluminal esophageal impedance and manometry predict postoperative dysphagia after laparoscopic Nissen fundoplication?

Laparoscopic Nissen fundoplication (LNF) is an effective treatment for gastroesophageal reflux disease; however, some patients develop dysphagia postoperatively. Manometry is used to evaluate disorders of peristalsis, but has not been proven useful to identify which patients may be at risk for postoperative dysphagia. Multichannel intraluminal impedance (MII) evaluates the effective clearance of a swallowed bolus through the esophagus. We hypothesized that MII combined with manometry may detect those patients most at risk of developing dysphagia after LNF. Between March 2003 and January 2007, 74 patients who agreed to participate in this study were prospectively enrolled. All patients completed a preoperative symptom questionnaire, MII/manometry, and 24-h pH monitoring. All patients underwent LNF. Symptom questionnaires were administered postoperatively at a median of 18 months (range: 6-46 months), and we defined dysphagia (both preoperatively and postoperatively) as occurring more than once a month with a severity >or=4 (0-10 Symptom Severity Index). Thirty-two patients (43%) reported preoperative dysphagia, but there was no significant difference in pH monitoring, lower esophageal sphincter pressure/relaxation, peristalsis, liquid or viscous bolus transit (MII), or bolus transit time (MII) between patients with and without preoperative dysphagia. In those patients reporting preoperative dysphagia, the severity of dysphagia improved significantly from 6.8 +/- 2 to 2.6 +/- 3.4 (P < 0.001) after LNF. Thirteen (17%) patients reported dysphagia postoperatively, 10 of whom (75%) reported some degree of preoperative dysphagia. The presence of postoperative dysphagia was significantly more common in patients with preoperative dysphagia (P= 0.01). Patients with postoperative dysphagia had similar lower esophageal sphincter pressure and relaxation, peristalsis, and esophageal clearance to those without dysphagia. Neither MII nor manometry predicts dysphagia in patients with gastroesophageal reflux disease or its occurrence after LNF. The presence of dysphagia preoperatively is the only predictor of dysphagia after LNF.

A diagnosis support system for capsule endoscopy

The diagnostic time required for a full, 8-hour video capsule endoscopy is usually between 45 and 120 min. The aim of this work is to evaluate the diagnostic time required when applying a method that adaptively controlls the image display rate. The advantage of the method is that the sequence can be played at high speed in stable smooth sequences to save time and then decreased at sequences where there are sudden rough changes, in order to assess suspicious findings detail. In this paper, this method is examined under real conditions: 10 sequences were independently evaluated by 4 medical doctors. The methods of evaluation include: 1) the time required for reading a sequence, 2) the percentage of abnormal regions accurately found, and 3) the manipulations of the evaluating physicians. The results indicate that the proposed method reduces diagnostic time to around 10 +/- 1.5% length of the sequence and is of valuable assistance to medical doctors.

RAS/ERK signaling promotes site-specific ribosomal protein S6 phosphorylation via RSK and stimulates cap-dependent translation

Converging signals from the mammalian target of rapamycin (mTOR) and phosphoinositide 3-kinase (PI3K) pathways are well established to modulate translation initiation. Less is known regarding the molecular basis of protein synthesis regulated by other inputs, such as agonists of the Ras/extracellular signal-regulated kinase (ERK) signaling cascade. Ribosomal protein (rp) S6 is a component of the 40S ribosomal subunit that becomes phosphorylated at several serine residues upon mitogen stimulation, but the exact molecular mechanisms regulating its phosphorylation and the function of phosphorylated rpS6 is poorly understood. Here, we provide evidence that activation of the p90 ribosomal S6 kinases (RSKs) by serum, growth factors, tumor promoting phorbol esters, and oncogenic Ras is required for rpS6 phosphorylation downstream of the Ras/ERK signaling cascade. We demonstrate that while ribosomal S6 kinase 1 (S6K1) phosphorylates rpS6 at all sites, RSK exclusively phosphorylates rpS6 at Ser(235/236) in vitro and in vivo using an mTOR-independent mechanism. Mutation of rpS6 at Ser(235/236) reveals that phosphorylation of these sites promotes its recruitment to the 7-methylguanosine cap complex, suggesting that Ras/ERK signaling regulates assembly of the translation preinitiation complex. These data demonstrate that RSK provides an mTOR-independent pathway linking the Ras/ERK signaling cascade to the translational machinery.

On the role of the starved codon and the takeoff site in ribosome bypassing in Escherichia coli

Translating ribosomes can skip over stretches of messenger RNA and resume protein chain elongation after a "bypassed" region. We have previously shown that limitation for isoleucyl-tRNA can initiate a ribosome bypass when an AUA codon is in the ribosomal A-site. We have now generalized this effect to other "hungry" codons calling for four different limiting aminoacyl-tRNA species, suggesting that a pause at any A-site will have this effect. We have assessed bypassing in a large family of reporters with nearly every different triplet in the "takeoff site", i.e. the P-site on the 5' side of the hungry codon, and an identical "landing site" codon 16 nucleotides downstream. The different takeoff sites vary over a factor of 50 in bypassing proficiency. At least part of this variation appears to reflect stability of the codon Colon, two colons anticodon interaction at the takeoff site, as indicated by the following: (a) the bypassing proficiency of different tRNAs shows a rough correlation with the frequency of A Colon, two colons U as opposed to G Colon, two colons C pairs in the codon Colon, two colons anticodon association; (b) specific tRNAs bypass more frequently from codons ending in U than from their synonym ending in C; (c) an arginine tRNA with Inosine in the wobble position which reads CGU, CGC, and CGA bypasses much more frequently from the last codon than the first two synonyms.

Recombinant prostate specific antigen inhibits angiogenesis in vitro and in vivo

BACKGROUND

Prostate specific antigen (PSA) is a kallikrein family member with serine protease activity commonly used as a diagnostic marker for prostate cancer. We recently described anti-angiogenic properties of PSA [Fortier et al.: JNCI 91:1635-1640].

METHODS

Two forms of PSA were cloned and expressed in Pichia pastoris: one, an intact PSA with an N-terminus of IVGGVS em leader; the second, an N-1 PSA variant. The recombinant proteins were tested for serine protease activity and for anti-angiogenic activity in vitro and in vivo.

RESULTS

The rate of substrate hydrolysis by the intact recombinant PSA was similar to that of PSA isolated and purified from human seminal plasma. In contrast, the N-1 PSA variant lacked serine protease activity. In an endothelial cell migration assay, the concentration that resulted in 50% inhibition (IC(50)) was: 0.5 microM for native PSA, 0.5 microM for intact recombinant protein, and 0.1 microM for the N-1 variant PSA. Both the intact recombinant and the N-1 recombinant PSA inhibited angiogenesis in vivo.

CONCLUSIONS

Purified recombinant PSA inhibits angiogenesis, proving the concept that PSA is an anti-angiogenic, and serine protease activity, as determined by synthetic substrate hydrolysis, is distinct from the anti-angiogenic properties of PSA.

Diagnosis of malignant granular cell tumor by fine needle aspiration cytology:

BACKGROUND

Malignant granular cell tumors (GCT) are the rarest of all sarcomas, and the histologic differentiation from their benign counterpart may be extremely difficult or impossible unless metastatic disease is demonstrated. To our knowledge, this is the first report of a malignant GCT diagnosed by fine needle aspiration (FNA) cytology.

CASE

A 70-year-old, Caucasian female presented with a progressively enlarging left supraclavicular mass. FNA of the mass revealed a metastatic tumor cytologically consistent with GCT. With this diagnosis, a search for other metastatic sites was initiated. Computed tomography (CT) scan revealed several tumor nodules in the lungs and liver. CT-guided FNA and tru-cut needle biopsy of a liver mass confirmed the diagnosis of metastatic GCT. In searching for a primary site, the patient revealed a clinical history of having had a tumor removed from her back two months before; it was reported to be an atypical GCT. Comparison of the three tumors revealed similar histologic, cytologic and immunohistochemical features.

CONCLUSION

Evidence of mild to moderate cytologic atypia; increased mitotic activity; locally aggressive growth; increased proliferative activity as demonstrated by immunohistochemical evaluation of proliferation markers; and DNA ploidy analysis, as reported for this case, may be helpful in predicting malignant behavior of GCTs.

Reduced pulmonary function and its associations in type 2 diabetes: the Fremantle Diabetes Study

To determine whether diabetes is associated with reduced lung function, we studied 421 Anglo-Celt/European subjects, representing 20.5% of all patients with type 2 diabetes identified in an urban Australian catchment area of 120097 people. In addition to collection of detailed demographic and diabetes-specific data, spirometry was performed and forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), vital capacity (VC) and peak expiratory flow (PEF) measured. When expressed as a percentage of those predicted (%pred) for age, sex and height, the means of all spirometric measures were reduced by > or =9.5%. After controlling for smoking, age and gender in a linear regression model, HbA(1c) was not associated with any measure of lung function (P>0.13) but diabetes duration was significantly associated with FEV1(%pred) and PEF(%pred) (P< or =0.04) and had borderline associations with FVC(%pred) and VC(%pred) (P< or =0.064). In separate analyses controlling for smoking alone, age, body mass index (BMI), coronary heart disease (CHD) and retinopathy were independently and inversely associated with FVC(%pred), FEV1(%pred) and VC(%pred) (P<0.05). In sub-group analyses, these three spirometric measures were associated with BMI, CHD and diabetes duration in males, and age and BMI in females. Pulmonary function is reduced in type 2 diabetes. Diabetes duration seems a more important influence than glycaemic control, but obesity and vascular disease may also contribute.

The influence of global discourse on lexical ambiguity resolution

The influence of global discourse on the resolution of lexical ambiguity was examined in a series of naming experiments. Two-sentence passages were constructed to bias either the dominant or the subordinate meaning of a homonym that was embedded in a locally ambiguous sentence. The results provided evidence for the immediate (0-msec interstimulus interval) resolution of lexical ambiguity and were subsequently replicated in Experiment 2, in which an 80-msec stimulus onset asynchrony exposure duration was employed for the homonyms. Strong dominant and subordinate biased discourse contexts activated only the contextually appropriate sense of a homonym. In Experiment 3, each sentence of the discourse was presented in isolation. The pattern of activation obtained in Experiments 1 and 2 was found to be contingent on the integration of the two sentences to construct an overall global discourse representation of the text. The results support a context-sensitive model of lexical ambiguity resolution.

Strength of discourse context as a determinant of the subordinate bias effect

Two experiments examined the influence of strength of discourse bias on lexical ambiguity resolution. Short passages were constructed to bias polarized ambiguous words (homonymous) strongly or weakly toward the dominant or subordinate meanings. Using a self-paced reading task in Experiment 1, it was demonstrated that in strongly biased discourse, reading times for homonyms in dominant discourse did not differ from those in subordinate discourse. However, when the discourse was weakly biased, homonyms were read faster in dominant discourse than in subordinate discourse. Experiment 2 combined the reading paradigm with a naming task in order to provide an assessment of specific word-meaning activation. Reading times on ambiguous words replicated the results of Experiment 1. In addition, naming latencies for probe words revealed that only the contextually appropriate sense of a homonym was activated in strongly biased discourse. In contrast, both contextually appropriate and inappropriate senses were activated following a weakly biased subordinate discourse, whereas only the dominant sense was activated following weakly biased dominant discourse. The results demonstrate (1) an immediate influence of prior discourse information on lexical processing; and (2) that the strength of discourse constraints can play a governing role in lexical ambiguity resolution. The results were interpreted within the framework of a context-sensitive model of lexical ambiguity resolution.

Strength of context does modulate the subordinate bias effect: a reply to Binder and Rayner

Using a self-paced reading task, Kellas, Martin, Yehling, Herman, and Vu (1995) demonstrated that strength of context can modulate the effects of meaning frequency. Binder and Rayner (1998) initially replicated the results, using eye-tracking methodology. On further examination of the stimuli, Binder and Rayner eliminated 43% of the stimulus set and found that context strength failed to modulate meaning frequency. Binder and Rayner's initial replication of Kellas et al. and the convergence of results between their two main experiments established the validity of self-paced reading as a measure of on-line reading, when compared with eye-tracking methodology. However, their central conclusion, that context strength cannot modulate the subordinate bias effect, is open to question. In this commentary, we examine the criteria adopted to exclude items from our homonym set and discuss the issue of local versus published norms. We also discuss the issue of context strength, as related to the specific rating procedures employed. Finally, we conclude that strong context can, in fact, eliminate the subordinate bias effect and that the context-sensitive model can more fully account for the available data on lexical ambiguity resolution.