Trans-acting dosage effects on the expression of model gene systems in maize aneuploids

The reduction in vigor of aneuploids was classically thought to be due to the imbalance of gene products expressed from the varied chromosome relative to those from the remainder of the genome. In this study, the dosage of chromosomal segments was varied, but the transcript level of most genes encoded therein showed compensation for the number of copies of the gene. Genes whose dosage was not altered were affected by aneuploidy of unlinked chromosomal segments. The phenotypic effects of aneuploidy and of a substantial fraction of quantitative variation are hypothesized to be the consequence of an altered dosage-sensitive regulatory system.

Expansion of mouse sertoli cells on microcarriers

BACKGROUND

Sertoli cells (SCs) have been described as the 'nurse cells' of the testis whose primary function is to provide essential growth factors and create an appropriate environment for development of other cells [for example, germinal and nerve stem cells (NSCs), used here]. However, the greatest challenge at present is that it is difficult to obtain sufficient SCs of normal physiological function for cell transplantation and biological medicine, largely due to traditional static culture parameter difficult to be monitored and scaled up.

OBJECTIVE

Operational stirred culture conditions for in vitro expansion and differentiation of SCs need to be optimized for large-scale culture.

MATERIALS AND METHODS

In this study, the culturing process for primary SC expansion and maintaining lack of differentiation was optimized for the first time, by using microcarrier bead technology in spinner flask culture. Effects of various feeding/refreshing regimes, stirring speeds, seed inoculum levels of SCs, and concentrations of microcarrier used for expansion of mouse SCs were also explored. In addition, pH, osmotic pressure and metabolic variables including consumption rates of glucose, glutamine, amino acids, and formation rates of lactic acid and ammonia, were investigated in culture.

RESULTS

After 6 days, maximal cell densities achieved were 4.6 x 10(6) cells/ml for Cytodex-1 in DMEM/FBS compared to 4.8 x 10(5) cells/ml in static culture. Improved expansion was achieved using an inoculum of 1 x 10(5) cells/ml and microcarrier concentration of 3 mg/ml at stirring speed of 30 rpm. RESULTS indicated that medium replacement (50% changed everyday) resulted in supply of nutrients and removal of waste products inhibiting cell growth, that lead to maintenance of cultures in steady state for several days. These conditions favoured preservation of SCs in the undifferentiated state and significantly increased their physiological activity and trophic function, which were assessed by co-culturing with NSCs and immunostaining.

CONCLUSION

Data obtained in this study demonstrate the vast potential of this stirred culture system for efficient, reproducible and cost-effective expansion of SCs in vitro. The system has advantages over static culture, which has major obstacles such as lower cell density, is time-consuming and susceptible to contamination.

Ex-vivo expansion of CFU-GM and BFU-E in unselected PBMC cultures with Flt3L is enhanced by autologous plasma

BACKGROUND

Previous ex-vivo expansion studies in our laboratory, comparing unselected and CD34(+)-selected PBMC, have shown no advantage for CD34(+) cell selection, in terms of the expansion achieved. Our goal was to develop procedures for consistent generation of large numbers of hematopoietic progenitor and post-progenitor cells from unselected PBMC.

METHODS

Unselected PBMC, collected from cancer patients undergoing apheresis prior to high-dose chemotherapy and autologous stem cell rescue, were expanded ex vivo in static cultures, without a stromal layer, in the presence of Flt3 ligand (Flt3L), a recombinant GM-CSF/IL-3 fusion protein (PIXY321), G-CSF and GM-CSF for 10 days.

RESULTS

The addition of 2% autologous plasma to this cytokine combination enhanced expansion of total cell numbers (3.2 fold versus 1.9 fold; p < 0.01), colony-forming units granulocyte-macrophage (CFU-GM) (22.0 fold versus 8.1 fold, p < 0.01) and burst-forming units erythroid (BFU-E) (17.6 fold versus 7.0 fold, 0.01 < p < 0.02). The optimal seeding density for a given specimen was inversely related to the frequency of CD34(+) cells in the sample. CFU-GM expansion with the Flt3L-containing cytokine cocktail was equivalent to that obtained with IL-3, IL-6, G-CSF and SCF, whether or not the cultures were supplemented with autologous plasma. In plasma-free cultures, BFU-E expansion was significantly higher with IL-3, IL-6, G-CSF and SCF than with Flt3L, PIXY321, G-CSF and GM-CSF. In the presence of autologous plasma, however BFU-E expansion was higher in the Flt3L-containing media. In comparison studies, autologous plasma suppressed BFU-E expansion in SCF-containing cultures. Consistent with our colony assay results, dual-parameter flow cytometric analysis of the expanded cell population revealed that supplementation with autologous plasma yielded a significant increase in the numbers of myeloid progenitors in Flt3L-containing cultures.

DISCUSSION

Unselected PBMC from cancer patients can be effectively expanded ex vivo in Flt3L, PIXY321, G-CSF and GM-CSF, supplemented with autologous plasma, yielding high numbers of myeloid and erythroid progenitors.

The radiation protection and therapy effects of mesenchymal stem cells in mice with acute radiation injury

The aim of this study was to investigate the effects and mechanisms of mesenchymal stem cells (MSCs) on haematopoietic reconstitution in reducing bone marrow cell apoptosis effects in irradiated mice, and to research the safe and effective dosage of MSCs in mice with total body irradiation (TBI). After BALB/c mice were irradiated with 5.5 Gy cobalt-60 gamma-rays, the following were observed: peripheral blood cell count, apoptosis rate, cell cycle, colony-forming unit-granulocyte macrophage (CFU-GM) and colony-forming unit-fibroblast (CFU-F) counts of bone marrow cells and pathological changes in the medulla. The survival of mice infused with three doses of MSCs after 8.0 Gy or 10 Gy TBI was examined. The blood cells recovered rapidly in the MSC groups. The apoptotic ratio of bone marrow cells in the control group was higher at 24 h after radiation. A lower ratio of G0/G1 cell cycle phases and a higher ratio of G2/M and S phases, as well as a greater number of haematopoietic islands and megalokaryocytes in the bone marrow, were observed in the MSC-treated groups. MSCs induced recovery of CFU-GM and CFU-GM and improved the survival of mice after 8 Gy TBI, but 1.5 x 10(8) kg(-1) of MSCs increased mortality. These results indicate that MSCs protected and treated irradiated mice by inducing haematopoiesis and reducing apoptosis. MSCs may be a succedaneous or intensive method of haematopoietic stem cell transplantation under certain radiation dosages, and could provide a valuable strategy for acute radiation syndrome.

Spatially encoded multibeam laser Doppler vibrometry using a single photodetector

A laser Doppler vibrometer with single photodetector is introduced to measure the vibration on multiple points of target simultaneously. A 2 x 5 beam array with various frequency shifts is generated by three acousto-optic devices, illuminating different points on a vibrating object. The reflected beams interfere with a reference beam on a high-speed photodetector, and the signal is amplified and digitized with a rate of 500 megasamples/s. To extract vibration information of different points, the carrier frequencies of each beam are elaborately designed so that they can be separated from cross-talk regions in the spectrum. The experimental results are compared with that from a commercial single-point vibrometer, and the comparison shows that it is possible to do a precise measurement on multiple points simultaneously using a single photodetector.

Expression analysis of Notch-related molecules in peripheral blood T helper cells of patients with rheumatoid arthritis

OBJECTIVE

Expression of Notch homologues in local tissue inflammation in rheumatoid arthritis (RA) and cultured synoviocytes has been reported, but the expression profile of Notch-related molecules in peripheral lymphocytes in RA remains unclear. In this study, we measured the expression of Notch receptors and downstream molecules in peripheral lymphocytes from RA patients.

METHODS

Expression of Notch receptors in peripheral lymphocytes of RA patients was assessed by both flow cytometry and real-time polymerase chain reaction (PCR). Expression of the representative Notch target gene HES-1 and the regulatory gene NUMB in purified T helper cells from RA patients was determined by real-time PCR, and expression of Notch intracellular domain (ICD) was determined by immunoblot analysis.

RESULTS

There was an increased expression of Notch 2, Notch 3, and Notch 4 in T helper cells from active RA patients, among which increased expression of Notch 3 was mainly by activated T cells. Notably, expression of Notch 3 in T cells decreased in inactive RA patients and the level was similar to that of healthy controls (HC). Notch receptors were rarely observed on B cells and no difference in expression was found between RA patients and HC. T helper cells from RA patients exhibited increased expression of the target gene HES-1 but decreased expression of the negative modulation gene NUMB of Notch signalling. There was also an increased nuclear translocation of Notch-ICD in T helper cells from active RA disease.

CONCLUSION

The present study demonstrated that T helper cells from RA patients display a significantly altered expression profile of Notch receptors and enhanced activation of Notch signalling compared with HC.

Exercise preconditioning reduces neuronal apoptosis in stroke by up-regulating heat shock protein-70 (heat shock protein-72) and extracellular-signal-regulated-kinase 1/2

Exercise preconditioning induces neuroprotection after stroke. We investigated the beneficial role of heat shock protein-70 (HSP-70) and phosphorylated extracellular-signal-regulated-kinase 1/2 (pERK 1/2), as they pertain to reducing apoptosis and their influence on Bcl-x(L), Bax, and apoptosis-inducing factor (AIF) in rats subjected to ischemia and reperfusion. Adult male Sprague-Dawley rats were subjected to 30 min of exercise on a treadmill for 1, 2, or 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Protein levels of HSP-70, pERK 1/2, Bcl-x(L), Bax, and AIF were analyzed using Western blot. Neuroprotection was based on levels of apoptosis (TUNEL) and infarct volume (Nissl staining). Immunocytochemistry was used for cellular expression of HSP-70 and pERK 1/2. Significant (P<0.05) up-regulation of HSP-70 and pERK 1/2 after 3 weeks of exercise coincided with significant (P<0.05) reduction in neuronal apoptosis and brain infarct volume. Inhibition of either one of these two factors showed a significant (P<0.05) reversal in the neuroprotection. Bax and AIF were down-regulated, while levels of Bcl-x(L) were up-regulated in response to stroke after exercise. Inhibiting HSP-70 or pERK 1/2 reversed this resultant increase or decrease. Our results indicate that exercise diminishes neuronal injury in stroke by up-regulating HSP-70 and ERK 1/2.

Exploratory analysis describing ultrasonic (US) evaluation of spleen size during peripheral blood progenitor cell (PBPC) mobilization by filgrastim in normal donors

7102

Background: Filgrastim is used to mobilize CD34+ cells into the peripheral blood that are collected by apheresis for allogeneic transplantation. We prospectively evaluated spleen size during PBPC mobilization Methods: Donors ≥18 yrs eligible to be PBPC donors per institutional guidelines enrolled. Splenic assessments were done before, during, and after PBPC mobilization. Filgrastim dose and schedule and leukapheresis (LK) procedures were per local practice. Spleen size by US was measured in 3 dimensions: longitudinal (craniocaudal), transverse, and diagonal (perpendicular to transverse). Splenic volume was estimated by taking the cross-product of 3 dimensions and multiplying by 0.52, approximating an ellipse volume. Stiff (ASH 2007) reported the primary endpoint, fold change from baseline in splenic volume during mobilization. Exploratory analyses, including a linear regression evaluating the effect of age and baseline spleen size on fold-change, were performed. Results: 309 enrolled, median age 44yrs, 56% male. Median fold volume change from baseline to first LK was 1.47, resolving to near baseline 1 week after last LK. No significant clinical sequelae, including splenic rupture, were reported. Older donors appeared to have the smallest baseline spleen volume and the largest fold change (table). Linear regression analyses indicated age was a significant predictor for both baseline spleen volume (p=0.0031) and spleen volume fold change from baseline at first LK (p=0.0499). Conclusions: During mobilization, spleen volume transiently increased from baseline to day of 1st LK and returned to near baseline 1 week after last LK. Older donors tended to have smaller baseline splenic volume and greater fold changes in spleen size. Preclinical models suggest decreasing hematopoietic stem cell homing after mobilization with aging (Morrison 1996; Wagers 2002), which could result in splenic accumulation of progenitor and stem cells.

[Table: see text]

[Table: see text]

Efficient generation of multi-copy strains for optimizing secretory expression of porcine insulin precursor in yeast Pichia pastoris

AIMS

This study attempted to fully explore the expression potentials of Pichia pastoris for producing porcine insulin precursor (PIP) through PIP copy number optimization.

METHODS AND RESULTS

Multi-copy strains were screened employing a highly efficient improved in vivo method and their copy numbers were quantified by real-time qPCR. A range of Mut(+)P. pastoris strains harbouring 0, 1, 3, 6, 12, 18, 29, 52 copies of PIP were obtained. After 96 h methanol induction, a bell-shaped correlation curve was observed between gene dosage and protein yield, and the maximum PIP expression level of 181 mg l(-1) was achieved by a 12-copy strain. Specific growth rate and methanol utilization capacity were found to decrease remarkably for high copy strains (>12 copies). Transcriptional analysis of KAR2 suggested higher copy strains were suffering more from ER stress.

CONCLUSIONS

A copy number around 12 is optimal for secretory expression of PIP in P. pastoris. Excess PIP gene dosage (>12 copies) significantly impaired the growth of P. pastoris hosts.

SIGNIFICANCE AND IMPACT OF THE STUDY

The methods developed and the discoveries made by this systematical investigation will be helpful to the application and understanding of Pichia pastoris expression system for heterologous overexpression.

Pre-ischemic exercise reduces matrix metalloproteinase-9 expression and ameliorates blood-brain barrier dysfunction in stroke

Exercise reduces ischemia and reperfusion (I/R) injury in the rat stroke model. We investigated whether pre-ischemic exercise ameliorates blood-brain barrier (BBB) dysfunction in stroke by reducing matrix metalloproteinase (MMP)-9 expression and strengthening basal lamina. Adult male Sprague-Dawley rats were subjected to a 30 min exercise program on a treadmill 5 days a week for 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament in the exercised and non-exercised groups. Brain infarction was measured and neurological deficits were scored. BBB dysfunction was determined by examining brain edema and Evans Blue extravasation. Expression of collagen IV, the major component of basal lamina essential for maintenance of the endothelial permeability barrier, was quantitatively detected by Western blot and immunocytochemistry. Ex vivo techniques were used to compare collagen IV-labeled vessels in response to ischemic insult. Temporal relationship of expression of MMP-9 and its endogenous inhibitor, the tissue inhibitors of metalloproteinase-1 (TIMP-1), was determined by real-time PCR for mRNA and Western blot for protein during reperfusion. Brain edema and Evans Blue leakage were both significantly (P<0.01) reduced after stroke in the exercised group, in association with reduced brain infarct volume and neurological deficits. Western blot analysis indicated that exercise enhanced collagen IV expression and reduced the collagen loss after stroke. Immunocytochemistry demonstrated that collagen IV-labeled vessels were significantly (P<0.01) increased in exercised rats. In the ex vivo study, after exercised brains were incubated with ischemic brain tissue, a significantly (P<0.01) higher level of collagen IV-labeled vessels was observed as compared with non-exercised brains following the same treatment. The ex vivo study also revealed a key role of MMP-9 in exercise-strengthened collagen IV expression against I/R injury. TIMP-1 protein levels were significantly (P<0.01) increased by exercise. Our results indicate that pre-ischemic exercise reduces brain injury by improving BBB function and enhancing basal lamina integrity in stroke. This study suggests that the neuroprotective effect of physical exercise is associated with an imbalance of MMP-9 and TIMP-1 expression.

Meniscus-climbing behavior and its minimum free-energy mechanism

Some insects can climb up the top of the meniscus surface generated by a hydrophilic wall by fixing their posture without moving their appendages [Baudoin, R. Bull. Biol. Fr. Belg. 1955, 89, 16. Hu, D. L.; Bush, J. W. M. Nature 2005, 437, 733]. To better understand this interesting phenomenon, we did meniscus-climbing experiments of bent copper sheets. It was found that the sheets do not always climb up the top of the meniscus surface but may stop and stably stay at various positions on the meniscus surface, depending upon their curvatures and masses, and that bent copper sheets can self-assemble into an oriented array (or an anisotropic form) through self-rotating on the water surface. The minimum energy mechanism of meniscus-climbing and self-rotating was then numerically studied. It was further shown that the meniscus-climbing and the rotating behavior is not only a general phenomenon for floating objects with hydrophilic surfaces, even those with fairly large sizes and weights (e.g., a metal bottle cap), but is also conditionally realizable for floating objects with hydrophobic surfaces.

Evolutionary tree reconstruction using structural expectation maximization and homotopy

The evolutionary tree reconstruction algorithm called SEMPHY using structural expectation maximization (SEM) is an efficient approach but has local optimality problem. To improve SEMPHY, a new algorithm named HSEMPHY based on the homotopy continuation principle is proposed in the present study for reconstructing evolutionary trees. The HSEMPHY algorithm computes the condition probability of hidden variables in the structural through maximum entropy principle. It can reduce the influence of the initial value of the final resolution by simulating the process of the homotopy principle and by introducing the homotopy parameter beta. HSEMPHY is tested on real datasets and simulated dataset to compare with SEMPHY and the two most popular reconstruction approaches PHYML and RAXML. Experimental results show that HSEMPHY is at least as good as PHYML and RAXML and is very robust to poor starting trees.

Hypoxia-mimetic agents desferrioxamine and cobalt chloride induce leukemic cell apoptosis through different hypoxia-inducible factor-1alpha independent mechanisms

Hypoxia presents pro-apoptotic and anti-apoptotic biphasic effects that appear to be dependent upon cell types and conditions around cells. The substantial reports demonstrated that commonly used hypoxia-mimetic agents cobalt chloride (CoCl(2)) and desferrioxamine (DFO) could also induce apoptosis in many different kinds of cells, but the mechanism was poorly understood. In this work, we compare the apoptosis-inducing effects of these two hypoxia-mimetic agents with acute myeloid leukemic cell lines NB4 and U937 as in vitro models. The results show that both of them induce these leukemic cells to undergo apoptosis with a loss of mitochondrial transmembrane potentials (DeltaPsi m), the activation of caspase-3/8 and the cleavage of anti-apoptotic protein Mcl-1, together with the accumulation of hypoxia-inducible factor-1 alpha (HIF-1alpha) protein, a critical regulator for the cellular response to hypoxia. Metavanadate and sodium nitroprusside significantly abrogate DFO rather than CoCl(2)-induced mitochondrial Delta Psi m collapse, caspase-3/8 activation, Mcl-1 cleavage and apoptosis, but they fail to influence DFO and CoCl(2)-induced HIF-1alpha protein accumulation. Moreover, inducible expression of HIF-1alpha gene dose not alter DFO and CoCl(2)-induced apoptosis in U937 cells. In conclusion, these results propose that although both DFO and CoCl(2)-induced leukemic cell apoptosis by mitochondrial pathway-dependent and HIF-1alpha-independent mechanisms, DFO and CoCl(2)-induced apoptosis involves different initiating signal pathways that remain to be investigated.

HbA(1c) as a screening tool for detection of Type 2 diabetes: a systematic review

AIM

To assess the validity of glycated haemoglobin A(1c) (HbA(1c)) as a screening tool for early detection of Type 2 diabetes.

METHODS

Systematic review of primary cross-sectional studies of the accuracy of HbA(1c) for the detection of Type 2 diabetes using the oral glucose tolerance test as the reference standard and fasting plasma glucose as a comparison. RESULTS Nine studies met the inclusion criteria. At certain cut-off points, HbA(1c) has slightly lower sensitivity than fasting plasma glucose (FPG) in detecting diabetes, but slightly higher specificity. For HbA(1c) at a Diabetes Control and Complications Trial and UK Prospective Diabetes Study comparable cut-off point of > or = 6.1%, the sensitivity ranged from 78 to 81% and specificity 79 to 84%. For FPG at a cut-off point of > or = 6.1 mmol/l, the sensitivity ranged from 48 to 64% and specificity from 94 to 98%. Both HbA(1c) and FPG have low sensitivity for the detection of impaired glucose tolerance (around 50%). CONCLUSIONS HbA(1c) and FPG are equally effective screening tools for the detection of Type 2 diabetes. The HbA(1c) cut-off point of > 6.1% was the recommended optimum cut-off point for HbA(1c) in most reviewed studies; however, there is an argument for population-specific cut-off points as optimum cut-offs vary by ethnic group, age, gender and population prevalence of diabetes. Previous studies have demonstrated that HbA(1c) has less intra-individual variation and better predicts both micro- and macrovascular complications. Although the current cost of HbA(1c) is higher than FPG, the additional benefits in predicting costly preventable clinical complications may make this a cost-effective choice.