HTLV-II-specific antisera raised in rabbits immunized with a synthetic peptide of HTLV-II envelope protein.

In order to discriminate HTLV-II from HTLV-I, HTLV-II-specific polyclonal antibodies against a synthetic peptide of HTLV-II envelope sequence were raised in rabbits. We immunized two adult rabbits with a KLH-conjugated synthetic peptide corresponding to the amino acid sequence 171-196 of the HTLV-II envelope sequence, which is a specific region for HTLV-II as evaluated with an ELISA method. The resulting rabbit antisera to the synthetic peptide reacted with gp46 of HTLV-II lysates in Western blot analysis but not with that of HTLV-I. Flow cytometric analysis and immunohistochemical study revealed that these affinity purified antisera recognized some HTLV-II-producing cell lines examined, but not HTLV-I-producing cell lines or other cell lines uninfected by HTLV. These findings indicate that these antisera specifically recognized the envelope glycoprotein (gp46) of HTLV-II and suggest the specificity of this region in the immune response to HTLV-II. Such antisera are useful in distinguishing between HTLV-I and HTLV-II infection and in determining the presence of individual HTLV-II-infected cells both in vivo and in vitro, including non-lymphoid cells. They may also assist in the elucidation of the pathogenesis of HTLV-II.     

Removal of catalytic activity by EDTA from antibody light chain

Gp41 peptide antigen of the HIV-1 envelope (TP41-1:TPRGPDRPEGIEEEGGERDR, a highly conserved region) was enzymatically degraded by the antibody light chain 41S-2-L after an induction period. The peptide bond between Glu¹⁴ and Gly¹⁵ was cleaved early in the reaction. When EDTA was added in the induction period, it inhibited the degradation of TP41-1 thus ceasing the catalytic activity of 41S-2-L. In contrast, when EDTA was added after the induction period, only a small reduction in the catalytic activity was observed. These observations suggest that metal ions are important in stimulating catalytic activity early in the reaction.     

Effects of fasting on mucus glycoprotein biosynthesis in rat stomach

Biosynthetic activity of gastrin mucus glycoprotein in rats after fasting for 24 and 72 hr was studied by the organ culture technique. Fasting produced a slight reduction in gastric mucus glycoprotein biosynthesis in the corpus and antrum (about 70-90% of fed rats). Sulfation of gastric mucus glycoprotein was restrained in the corpus (18% in control for 72 hr).     

Estimation of rat thermoregulatory ability based on body temperature response to heat

A new simple but general estimation method for survival time in a hot environment is presented in this study. Even in heat-tolerant rats showing a triphasic heat response, an accurate estimation of survival time (ST) is possible. Rat groups, which included some heat-tolerant individuals, were exposed to 42.5 degrees C, 40% rh. Colonic temperature (Tco) was measured continuously by copper-constantan thermocouple. The ST (Y) of male and female rats were expressed as a linear function of time (X) until the Tco of 42.5 degrees C was reached: Y = 0.976X + 30.6 and Y = 0.968X + 31.6, respectively. A Tco of 42.5 degrees C at rest was just below the maximum survivable body temperature and above the steady-state equilibrium Tco levels during the second phase of the triphasic heat-response curve. Heat-tolerant individuals showed lower equilibrium temperatures than heat-intolerant rats. All 140 rats survived the Tco of 42.5 degrees C and lived for more than 8 wk, thus enabling them to be used for future experiments on thermoregulation. The heat survivors were able to reproduce, and their genetically controlled offspring could be used for thermoregulatory experiments.     

A molecular dynamics study on the thermal rectification effect at the solid–liquid interfaces between the face-centred cubic (FCC) of gold (Au) with the surfaces of (100), (110) and (111) crystal planes facing the liquid methane (CH4)

A molecular dynamics study on the solid–liquid (S-L) interfaces for solid wall of gold having the face-centred cubic of (100), (110) and (111) crystal planes contacting liquid methane was examined using non-equilibrium molecular dynamics simulations. An investigation on the thermal rectification effect was performed by measuring the thermal boundary conductance (TBC) at the S-L interface. Thermal rectification can be defined as the differences in the TBC at the interface between the two opposite heat flow directions; one is from the liquid to solid and vice versa. The thermal rectifications are up to 13% for (110) crystal plane, followed by 6% and 0.3% for (111) and (100) crystal planes, respectively. It was found that the TBC at the S-L interface was influenced by the magnitude of the adsorption of liquid molecules at the vicinity of the interface. The results show that due to the different temperature distribution, different magnitude of the adsorption of liquid molecules is generated for the two opposite heat flow directions. On the surface of the solid walls for (110) crystal plane, where lattice-scale corrugation exists, it was found that there exists difference in distance between the surface layers of the solid and liquid across the interface between the cases of the two opposite heat flow directions, which affects the TBC at the interface. The present results suggest that the factors that influence the thermal rectification at the S-L interface are the magnitude of the adsorption of liquid molecules and the surface structure of the solid walls that differ significantly among the three types of crystal planes.     

Inverse and reciprocal regulation of p53/p21 and Bmi-1 modulates vasculogenic differentiation of dental pulp stem cells

Dental pulp stem cells (DPSC) are capable of differentiating into vascular endothelial cells. Although the capacity of vascular endothelial growth factor (VEGF) to induce endothelial differentiation of stem cells is well established, mechanisms that maintain stemness and prevent vasculogenic differentiation remain unclear. Here, we tested the hypothesis that p53 signaling through p21 and Bmi-1 maintains stemness and inhibits vasculogenic differentiation. To address this hypothesis, we used primary human DPSC from permanent teeth and Stem cells from Human Exfoliated Deciduous (SHED) teeth as models of postnatal mesenchymal stem cells. DPSC seeded in biodegradable scaffolds and transplanted into immunodeficient mice generated mature human blood vessels invested with smooth muscle actin-positive mural cells. Knockdown of p53 was sufficient to induce vasculogenic differentiation of DPSC (without vasculogenic differentiation medium containing VEGF), as shown by increased expression of endothelial markers (VEGFR2, Tie-2, CD31, VE-cadherin), increased capillary sprouting in vitro; and increased DPSC-derived blood vessel density in vivo. Conversely, induction of p53 expression with small molecule inhibitors of the p53-MDM2 binding (MI-773, APG-115) was sufficient to inhibit VEGF-induced vasculogenic differentiation. Considering that p21 is a major downstream effector of p53, we knocked down p21 in DPSC and observed an increase in capillary sprouting that mimicked results observed when p53 was knocked down. Stabilization of ubiquitin activity was sufficient to induce p53 and p21 expression and reduce capillary sprouting. Interestingly, we observed an inverse and reciprocal correlation between p53/p21 and the expression of Bmi-1, a major regulator of stem cell self-renewal. Further, direct inhibition of Bmi-1 with PTC-209 resulted in blockade of capillary-like sprout formation. Collectively, these data demonstrate that p53/p21 functions through Bmi-1 to prevent the vasculogenic differentiation of DPSC.Subject terms: Morphogen signalling, Mesenchymal stem cells, Stem-cell differentiation