Relief of hypoxia by angiogenesis promotes neural stem cell differentiation by targeting glycolysis

Blood vessels are part of the stem cell niche in the developing cerebral cortex, but their in vivo role in controlling the expansion and differentiation of neural stem cells (NSCs) in development has not been studied. Here, we report that relief of hypoxia in the developing cerebral cortex by ingrowth of blood vessels temporo‐spatially coincided with NSC differentiation. Selective perturbation of brain angiogenesis in vessel‐specific Gpr124 null embryos, which prevented the relief from hypoxia, increased NSC expansion at the expense of differentiation. Conversely, exposure to increased oxygen levels rescued NSC differentiation in Gpr124 null embryos and increased it further in WT embryos, suggesting that niche blood vessels regulate NSC differentiation at least in part by providing oxygen. Consistent herewith, hypoxia‐inducible factor (HIF)‐1α levels controlled the switch of NSC expansion to differentiation. Finally, we provide evidence that high glycolytic activity of NSCs is required to prevent their precocious differentiation in vivo. Thus, blood vessel function is required for efficient NSC differentiation in the developing cerebral cortex by providing oxygen and possibly regulating NSC metabolism.     

A reliability and validity study for Scolioscan: a radiation-free scoliosis assessment system using 3D ultrasound imaging

Background

Radiographic evaluation for patients with scoliosis using Cobb method is the current gold standard, but radiography has radiation hazards. Several groups have recently demonstrated the feasibility of using 3D ultrasound for the evaluation of scoliosis. Ultrasound imaging is radiation-free, comparatively more accessible, and inexpensive. However, a reliable and valid 3D ultrasound system ready for clinical scoliosis assessment has not yet been reported. Scolioscan is a newly developed system targeted for scoliosis assessment in clinics by using coronal images of spine generated by a 3D ultrasound volume projection imaging method. The aim of this study is to test the reliability of spine deformity measurement of Scolioscan and its validity compared to the gold standard Cobb angle measurements from radiography in adolescent idiopathic scoliosis (AIS) patients.

Methods

Prospective study divided into two stages: 1) Investigation of intra- and inter- reliability between two operators for acquiring images using Scolioscan and among three raters for measuring spinal curves from those images; 2) Correlation between the Cobb angle obtained from radiography by a medical doctor and the spine curve angle obtained using Scolioscan (Scolioscan angle). The raters for ultrasound images and the doctors for evaluating radiographic images were mutually blinded. The two stages of tests involved 20 (80 % females, total of 26 angles, age of 16.4?±?2.7 years, and Cobb angle of 27.6?±?11.8°) and 49 (69 % female, 73 angles, 15.8?±?2.7 years and 24.8?±?9.7°) AIS patients, respectively. Intra-class correlation coefficients (ICC) and Bland-Altman plots and root-mean-square differences (RMS) were employed to determine correlations, which interpreted based on defined criteria.

Results

We demonstrated a very good intra-rater and intra-operator reliability for Scolioscan angle measurement with ICC larger than 0.94 and 0.88, respectively. Very good inter-rater and inter-operator reliability was also demonstrated, with both ICC larger than 0.87. For the thoracic deformity measurement, the RMS were 2.5 and 3.3° in the intra- and inter-operator tests, and 1.5 and 3.6° in the intra- and inter-rater tests, respectively. The RMS differences were 3.1, 3.1, 1.6, 3.7° in the intra- and inter-operator and intra- and inter-rater tests, respectively, for the lumbar angle measurement. Moderate to strong correlations (R²?>?0.72) were observed between the Scolioscan angles and Cobb angles for both the thoracic and lumbar regions. It was noted that the Scolioscan angle slightly underestimated the spinal deformity in comparison with Cobb angle, and an overall regression equation y?=?1.1797x (R²?=?0.76) could be used to translate the Scolioscan angle (x) to Cobb angle (y) for this group of patients. The RMS difference between Scolioscan angle and Cobb angle was 4.7 and 6.2°, with and without the correlation using the overall regression equation.

Conclusions

We showed that Scolioscan is reliable for measuring coronal deformity for patients with AIS and appears promising in screening large numbers of patients, for progress monitoring, and evaluation of treatment outcomes. Due to it being radiation-free and relatively low-cost, Scolioscan has potential to be widely implemented and may contribute to reducing radiation dose during serial monitoring.

     

Serum IgG response to Burkholderia cepacia outer membrane antigens in cystic fibrosis: Assessment of cross-reactivity with Pseudomonas aeruginosa

Abstract Burkholderia cepacia (Pseudomonas cepacia) is now recognised as an important pathogen in cystic fibrosis patients, and several reports have suggested that sputum-culture-proven colonisation occurs despite the presence of specific antibody. In an attempt to establish the use of antibody studies as diagnostic and prognostic indicators of B. cepacia infection, we have examined the IgG response to B. cepacia outer membrane proteins and lipopolysaccharide in patients also colonised with P. aeruginosa . The B. cepacia strains were grown in a modified iron-depleted chemically defined medium and outer membrane components examined by SDS-PAGE and immunoblotting. IgG antibodies were detected against B. cepacia outer membrane antigens, which were not diminished by extensive preadsorption with P. aeruginosa . The response to B. cepacia O-antigen could be readily removed by adsorption of serum either with B. cepacia whole cells or purified LPS, whereas we were unable to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells. The inability to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells maybe due to non-exposed surface epitopes. Several B. cepacia sputum-culture negative patients colonised with P. aeruginosa had antibodies directed against B. cepacia outer membrane protein. This study suggests that there is a specific anti- B. cepacia LPS IgG response, which is not due to antibodies cross-reactive with P. aeruginosa . Our studies indicate that much of the B. cepacia anti-outer membrane protein response is specific and not attributable to reactivity against co-migrating LPS.     

Concentration of plasminogen activators and inhibitor in the human endometrium at different phases of the menstrual cycle.

The concentrations of tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA) and plasminogen activator inhibitor (PAI-1) have been determined in endometrial curettings obtained from 46 subfertile women during proliferative, early or late secretory phases of the menstrual cycle. t-PA activity and antigen concentrations was significantly higher (P < 0.001) in late secretory endometrium than in proliferative or early secretory endometrium. Higher concentrations of PAI-1 antigen (P < 0.05) were also noted in late secretory phase than in proliferative and early secretory endometrium. However, u-PA concentration was not significantly different and no PAI activity could be demonstrated in the menstrual phases studied. Zymography studies confirmed the presence of both t-PA and u-PA in the endometrium. Ovarian hormonal patterns may therefore influence the activity of plasminogen activators especially of t-PA in the endometrium during various phases of the menstrual cycle.     

Geographical variation in dormancy in a copepod: evidence from population crosses

Populations of the freshwater copepod Mesocyclops edax inhabiting Michigan lakes are dormant during winter, whereas populations inhabiting Florida lakes develop and reproduce continuously throughout the year. A Michigan and a Florida population were exposed to dormancy inducing conditions (low temperature and short photoperiod) in the laboratory and observed for indications of dormancy. All Michigan individuals and a small percentage of the Florida individuals entered dormancy as indicated by prolonged duration of the fourth copepodid instar and cessation of feeding. I suggest that in these population these observations represent diapause, rather than quiescence. The two populations were crossbred to examine the nature of inheritance of dormancy. The F₁ hybrids exhibited an incidence of diapause approximately intermediate between the Florida and Michigan parental stocks. The backcrosses of F₁ individuals to the Michigan and Florida stocks, respectively, exhibited a high and an intermediate incidence of diapause. Survival of the F₂ crosses was very low. The present study presents evidence of genetic differentiation between the Michigan and Florida populations of M. edax with respect to ability to diapause.     

Reinforcement context and resistance to change

Eight pigeons responded in a multiple variable-interval (VI) schedule in which a constant component always delivered 40rft/h, and an alternated component was either rich (200rft/h) or lean (6.67rft/h) in different conditions. Four tests of resistance to change were conducted in each condition: prefeeding, full extinction, constant-component-only extinction, and response-independent food. Resistance to both prefeeding and full extinction in the constant component varied inversely with the reinforcement rate in the alternated component, but resistance to response-independent food did not. The extinction and response-independent food results were consistent with [J. Exp. Psychol.: Anim. Behav. Proc. 25 (1999) 256] behavioral momentum model. Maintaining reinforcement in the alternated component increased resistance to extinction in the constant component, as predicted by the behavioral momentum model but not accounts of multiple-schedule performance based on [J. Exp. Anal. Behav. 13 (1970) 243] equation. Overall, the momentum model gave a good account of the results with the exception of the prefeeding data. Possible ways to reconcile the prefeeding results with behavioral momentum theory are considered.     

Comparative evaluation of different cell disruption methods for the release of recombinant hepatitis B core antigen from <Emphasis Type="Italic">Escherichia coli</Emphasis>

A comparative evaluation of five different cell-disruption methods for the release of recombinant hepatitis B core antigen (HBcAg) from Escherichia coli was investigated. The cell disruption techniques evaluated in this study were high-pressure homogenization, batch-mode bead milling, continuous-recycling bead milling, ultrasonication, and enzymatic lysis. Continuous-recycling bead milling was found to be the most effective method in terms of operating cost and time. However, the highest degree of cell disruption and amounts of HBcAg were obtained from the high-pressure homogenization process. The direct purification of HBcAg from the unclarified cell disruptate derived from high-pressure homogenization and bead milling techniques, using batch anion-exchange adsorption methods, showed that the conditions of cell disruption have a substantial effect on subsequent protein recovery steps.     

Isolation and characterisation of an equol-producing mixed microbial culture from a human faecal sample and its activity under gastrointestinal conditions

Only about one third of humans possess a microbiota capable of transforming the dietary isoflavone daidzein into equol. Little is known about the dietary and physiological factors determining this ecological feature. In this study, the in vitro metabolism of daidzein by faecal samples from four human individuals was investigated. One culture produced the metabolites dihydrodaidzein and O-desmethylangolensin, another produced dihydrodaidzein and equol. From the latter, a stable and transferable mixed culture transforming daidzein into equol was obtained. Molecular fingerprinting analysis (denaturing gradient gel electrophoresis) showed the presence of four bacterial species of which only the first three strains could be brought into pure culture. These strains were identified as Lactobacillus mucosae EPI2, Enterococcus faecium EPI1 and Finegoldia magna EPI3, and did not produce equol in pure culture. The fourth species was tentatively identified as Veillonella sp strain EP. It was found that hydrogen gas in particular, but also butyrate and propionate, which are all colonic fermentation products from poorly digestible carbohydrates, stimulated equol production by the mixed culture. However, when fructo-oligosaccharides were added, equol production was inhibited. Furthermore, the equol-producing capacity of the isolated culture was maintained upon its addition to a faecal culture originating from a non-equol-producing individual.     

Modeling and simulation of the swelling behavior of pH-stimulus-responsive hydrogels

The modulation of the swelling ability of the hydrogel matrix by pH-stimulus enables the dynamic control of the swelling forces, thereby obtaining effective diffusivity and permeability of the solutes, or mechanical energy from the hydrogel. In this work, a chemo-electro-mechanical model describing hydrogel behavior, based on multi-field effects, is developed to simulate the swelling and shrinking of these fascinating bio-materials, and it is termed the multi-effect-coupling pH-stimulus (MECpH) model. This model accounts for the ionic fluxes within both the hydrogel and solution, the coupling between the electric field, ionic fluxes, and mechanical deformations of the hydrogel. The main contribution of this model is to incorporate the relationship between the concentrations of the ionized fixed-charge groups and the diffusive hydrogen ion, which follows a Langmuir isotherm, into the Poisson-Nernst-Planck system. To validate this MECpH model, one-dimensional steady-state simulations under varying pH solution are carried out via a meshless Hermite-Cloud methodology, and the numerical results are compared with available experimental data. It is shown that the presently developed MECpH model is accurate, efficient, and numerically stable.