Tregs are involved in VEGFA/ VASH1-related angiogenesis pathway in ovarian cancer

Vasohibin1 (VASH1) is a kind of vasopressor, produced by negative feedback from vascular endothelial growth factor A (VEGFA). Anti-angiogenic therapy targeting VEGFA is currently the first-line treatment for advanced ovarian cancer (OC), but there are still many adverse effects. Regulatory T cells (Tregs) are the main lymphocytes mediating immune escape function in the tumor microenvironment (TME) and have been reported to influence the function of VEGFA. However, whether Tregs are associated with VASH1 and angiogenesis in TME in OC is unclear. We aimed to explore the relationship between angiogenesis and immunosuppression in the TME of OC. We validated the relationship between VEGFA, VASH1, and angiogenesis in ovarian cancer and their prognostic implications. The infiltration level of Tregs and its marker forkhead box protein 3 (FOXP3) were explored in relation to angiogenesis-related molecules. The results showed that VEGFA and VASH1 were associated with clinicopathological stage, microvessel density and poor prognosis of ovarian cancer. Both VEGFA and VASH1 expression were associated with angiogenic pathways and there was a positive correlation between VEGFA and VASH1 expression. Tregs correlated with angiogenesis-related molecules and indicated that high FOXP3 expression is harmful to the prognosis. Gene set enrichment analysis (GSEA) predicted that angiogenesis, IL6/JAK/STAT3 signaling, PI3K/AKT/mTOR signaling, TGF-β signaling, and TNF-α signaling via NF-κB may be common pathways for VEGFA, VASH1, and Tregs to be involved in the development of OC. These findings suggest that Tregs may be involved in the regulation of tumor angiogenesis through VEGFA and VASH1, providing new ideas for synergistic anti-angiogenic therapy and immunotherapy in OC.

Development of Nomogram Models Based on Peripheral Blood Score and Clinicopathological Parameters to Predict Preoperative Advanced Stage and Prognosis for Epithelial Ovarian Cancer Patients

Purpose

Nutritional and inflammatory states are crucial in cancer development. The purpose of this study is to construct a scoring system grounded on peripheral blood parameters associated with nutrition and inflammation and explore its value in stage, overall survival (OS), and progression-free survival (PFS) prediction for epithelial ovarian cancer (EOC) patients.

Patients and Methods

Four hundred and fifty-three EOC patients were retrospectively identified and their clinical data and relevant peripheral blood parameters were collected. The ratio of neutrophil to lymphocyte, lymphocyte to monocyte, fibrinogen to lymphocyte, total cholesterol to lymphocyte and albumin level were calculated and dichotomized. A scoring system named peripheral blood score (PBS) was constructed. Univariate and multivariate Logistic or Cox regression analyses were used to select independent factors; these factors were then used to develop nomogram models of advanced stage and OS, PFS, respectively. The internal validation and DCA analysis were performed to evaluate models.

Results

Lower PBS indicated a better prognosis and higher PBS indicated inferior. High PBS is associated with advanced stage, high CA125, serous histological type, poor differentiation, and accompanied ascites. The logistic regression showed age, CA125, and PBS were independent factors for the FIGO III-IV stage. The nomogram models for advanced FIGO stage based on these factors showed good efficiency. FIGO stage, residual disease, and PBS were independent factors affecting OS and PFS, the nomogram models composed of these factors had good performance. DCA curves revealed the models augmented net benefits.

Conclusion

PBS can be a noninvasive biomarker for EOC patients' prognosis. The related nomogram models could be powerful, cost-effective tools to provide information of advanced stage, OS, and PFS for EOC patients.

A newborn with coronavirus (COVID-19) disease: A brief report

There are few neonates reported with COVID-19 disease. To date there is no clear evidence of vertical transmission of the virus before birth. We report a 4-day old infant born to an asymptomatic mother who developed infection with SARS-CoV-2, likely from contact with parents during the postnatal period.

W-GPCR Routing Method for Vehicular Ad Hoc Networks

The high-speed dynamics of nodes and rapid change of network topology in vehicular ad hoc networks (VANETs) pose significant challenges for the design of routing protocols. Because of the unpredictability of VANETs, selecting the appropriate next-hop relay node, which is related to the performance of the routing protocol, is a difficult task. As an effective solution for VANETs, geographic routing has received extensive attention in recent years. The Greedy Perimeter Coordinator Routing (GPCR) protocol is a widely adopted position-based routing protocol. In this paper, to improve the performance in sparse networks, the local optimum, and the routing loop in the GPCR protocol, the Weighted-GPCR (W-GPCR) protocol is proposed. Firstly, the relationship between vehicle node routing and other parameters, such as the Euclidean distance between node pairs, driving direction, and density, is analyzed. Secondly, the composite parameter weighted model is established and the calculation method is designed for the existing routing problems; the weighted parameter ratio is selected adaptively in different scenarios, so as to obtain the optimal next-hop relay node. In order to verify the performance of the W-GPCR method, the proposed method is compared with existing methods, such as the traditional Geographic Perimeter Stateless Routing (GPSR) protocol and GPCR. Results show that this method is superior in terms of the package delivery ratio, end-to-end delay, and average hop count.

Ammonia sensing by closely packed WO3 microspheres with oxygen vacancies

Ammonia (NH₃), is a precursor for the formation of atmospheric fine particulate matter (PM_2.5), and thus establishing efficient and cost-effective methods to detect ammonia emission is highly desired. Transition metal oxide semiconductors-based sensors for electrochemical gas sensing have been extensively explored. Among various types of semiconductors, tungsten oxide (WO₃) possesses an anisotropic layered crystalline structure and is recognized as a promising material for gas sensing. However, the performance of commercial WO₃ is unsatisfactory because of its high impedance and low charge transportation efficiency. Thus, the modification of commercial WO₃ is needed to make it an efficient ammonia sensor material. In this work, closely packed WO₃ microspheres with oxygen vacancies were synthesized successfully through a novel two-step hydrothermal route. Our WO₃ showed a good selectivity to ammonia sensing, and its response intensity was 2.6 times higher than that of commercial WO₃ because of its optimized conductivity. Moreover, the mechanism behind its robust ammonia sensing performance was elucidated. The effectiveness of the as-prepared WO₃ microspheres for ammonia sensing also suggests a new strategy for modifying transition metal oxide materials.

Porous ZnO-Coated Co3O4 Nanorod as a High-Energy-Density Supercapacitor Material

Co₃O₄ with a high theoretical capacitance has been widely recognized as a promising electrode material for supercapacitor, but its poor electrical conductivity and stability limit its practical applications. Here, we developed an effective synthetic route to synthesize one-dimensional (1D) porous ZnO/Co₃O₄ heterojunction composites. Benefiting from the heterostructure to promote the charge transfer and protect Co₃O₄ from corrosion and the 1D porous structure to improve ion diffusion and prevent structural collapse in charge and discharge process, the as-prepared ZnO/Co₃O₄ composites exhibited an excellent capacitive performance and good cycling stability. The specific capacitance of the ZnO/Co₃O₄-450 (1135 F g^-1 at 1 A g^-1) was 1.4 times higher than that of Co₃O₄ (814 F g^-1), and the high-rate performance for ZnO/Co₃O₄-450 was 4.9 times better than that of Co₃O₄. Also, approximately 83% of its specific capacitance was retained after 5000 cycles at 10 A g^-1. Most importantly, the as-fabricated asymmetric supercapacitor, with a ZnO/Co₃O₄-450 positive electrode and an activated carbon negative electrode, delivered a prominent energy density of 47.7 W h kg^-1 and a high power density of 7500 W kg^-1. Thus, the ZnO/Co₃O₄ composites could serve as a high-activity material for supercapacitor and the preparation method also offers an attractive strategy to enhance the capacitive performance of Co₃O₄.

Advanced three dimensional characterization of silica-based ultraporous materials

Whatever the field of application in building, transportation, packaging, etc., the energy losses must be reduced. In this context, the development of superinsulating materials is mandatory. Ultra-porous silica aerogels are good candidates.

Effect of the Schneiderian membrane on the formation of bone after lifting the floor of the maxillary sinus: an experimental study in dogs

A titanium membrane was used to isolate the Schneiderian membrane of the bony walls of the sinus so that we could investigate their role on the formation of bone after sinus lifts compared with a control group (conventional raising of the sinus floor) in which we did not use a membrane to isolate any area. Three canine models of lifting the sinus floor using the lateral window technique were established: conventional lifting of the floor (control group), raising of the floor with the mucosa shielded (mucosal shielding group), and raising of the floor with the bony wall shielded (bony wall shielding group). The formation of bone one and three months after the sinus floor had been lifted was compared in each group both grossly and by histopathological examination. An appreciable amount of new bone had formed in the control group, with abundant areas near the inferior bony wall, and some near the raised Schneiderian membrane. Similarly, new bone had also formed in the mucosal shielding group, with abundant new bone near the inferior bony wall, but none near the raised Schneiderian membrane. However, there was considerably less new bone in the bony wall shielding group, with none in tissues adjacent to the inferior bony wall and little in tissues near the raised Schneiderian membrane. The Schneiderian membrane has osteogenic capability and participates in the formation of bone after the sinus floor has been lifted. However, its osteogenic role is weaker than that of the surrounding bony wall of the maxillary sinus.

Bone marrow-derived mesenchymal stem cells are capable of mediating hepatitis B virus infection in injured tissues

We have previously showed that endothelial progenitor cells (EPCs) through uptake of hepatitis B virus (HBV) may play a critical role in mediating extrahepatic HBV diseases. However, it remains to be elucidated whether mesenchymal stem cells (MSCs) are capable of mediating HBV trans-infection into extrahepatic tissues.

METHODS AND RESULTS

In this study, we showed that HBV antigens, HBV DNA and the viral particles were detected in MSCs after 3 days virus challenge. Neither HBV covalently closed circular DNA nor pregenomic RNA were detected in MSCs. Intravenously transplantation of HBV-exposed MSCs into myocardial infarction mouse model resulted in incorporation of HBV into injured heart and other damaged tissues.

CONCLUSION

These results indicate that MSCs could serve as an additional extrahepatic virus reservoir, which may play a role at least in part in mediating HBV trans-infection into the injured tissues through the process of MSCs recruitment.

A L.E.A.P.S. heteroconjugate vaccine containing a T cell epitope from HSV-1 glycoprotein D elicits Th1 responses and protection

The L.E.A.P.S. heteroconjugate vaccine antigen (JgD), composed of a T cell epitope from glycoprotein D (gD(8-23)) of herpes simplex virus (HSV) linked with a peptide sequence from beta-2-microglobulin (aa38-50), elicited protection against lethal intraperitoneal (IP) challenge and prevented disease signs in most, and limited disease progression, for the rest of BALB/c mice challenged in the epidermal abrasion-zosteriform spread mouse infection model. JgD elicited a Th1 response in vaccinated mice as indicated by delayed type hypersensitivity (DTH) responses to HSV antigen, and gD and virion specific antibodies with an IgG2a/IgG1 >1. Vaccination with the JgD peptide delayed the onset of disease signs, reduced severity of the disease and reduced mortality rates in mice with different MHC backgrounds as compared to their respective control mice. CD8 cells were demonstrated as important for initiation of the immune response to JgD and CD4 cells and interferon gamma (IFN-gamma) for delivering immune protection in BALB/c mice, as indicated in monoclonal antibody ablation studies. JgD, and other J-L.E.A.P.S. vaccine antigens, appear to prime T cells to initiate a Th1 response, which is subsequently boosted upon viral challenge to result in protection.

FE-simulation of bone modeling around an implant in the mandible in two-stage versus one-stage implantation

On the basis of a FE-model for bone modeling which takes into account bone apposition and resorption as well as revascularization, the ossification process of the repair zone around a dental implant in the mandible is studied for two alternatives. The conventional two-stage implantation method consists of a healing phase (no direct loading of the implant) and a functional phase (direct loading). In the recently applied one-stage method the healing phase is omitted (early loading). The presented simulations show that both processes finally lead to the same degree of ossification of the repair zone. However, the relative displacements and rotations of the implant are considerably larger in the one-stage process and might therefore possibly lead to a violation of the bond between implant and bone.

Multiple mechanisms for HSV-1 induction of interferon alpha production by peripheral blood mononuclear cells

UV-inactivated, infectious, and other forms of herpes simplex virus 1 (HSV-1) induced interferon (IFN) production by different routes in myeloid origin mononuclear cells (MOMC) (consisting predominantly of monocytes). GM-CSF activated the MOMC (G-MOMC) to produce greater amounts of interferon while differentiation to DC, by the addition of granulocyte macrophage colony stimulating factor (GM-CSF) and calcium ionophore (GA-MOMC), reduced the levels of interferon production upon challenge with some HSV strains. UV-inactivated virus induced more interferon than infectious virus. L-fucose, an antagonist of the mannose receptor, inhibited the induction of IFN-alpha by UV-inactivated virus and gB(-) virus (defective in penetration) in MOMC and GA-MOMC but not G-MOMC. L-fucose had little effect on interferon induction by infectious HSV-1. The insensitivity of the G-MOMC to fucose inhibition distinguishes these interferon producing cells from the pDC2 cells previously described as natural interferon producing cells. The mannose receptor appears to be involved in the response to non-infectious forms of HSV but infectious virus appears to use a different pathway. These studies suggest that non-infectious virions and HSV infected cell debris effectively stimulate monocytes and pre-dendritic cells to produce IFN-alpha to initiate host protection against HSV infection.

An improved method to evaluate secretory activity of isolated gastric glands and cells

The accumulation of [14C]aminopyrine (AP) is a valuable and widely used method to probe acid secretion of gastric glands and parietal cells. Usually, the dry weight of glands is used to normalize the AP accumulation ratio, and since the nonhomogeneity of the suspension makes it impossible to evenly distribute glands by simple pipetting, it is necessary to scrupulously dry and weigh each and every experimental sample. Thus, massive, time-consuming procedures of tube drying and weighing are involved. Moreover, the weighing of approximately 1 mg dried gland samples in a 1-g Eppendorf tube introduces considerable sample variance. Here, we present a modified protocol to simplify the AP accumulation method by introducing a generic 3H labeling of protein for normalization. Freshly isolated glands were treated with high specific activity 3H-labeled succinimidyl propionate (3H-succ, 60 Ci/mmol) for 10 min at room temperature during the normal isolation/washing procedure. This reagent reacts with primary amines, and even at normal cell pH the efficiency of reaction (25-30%) is more than adequate. The 3H-labeled glands are then processed normally with simultaneous monitoring of 3H (representing gland amount) and AP (representing the extent of acid accumulation) in separate energy windows of a liquid scintillation counter. Dose- and time-dependent efficiency of 3H labeling were evaluated. The relations between labeling and gland protein and dry weight were linear. No detrimental effects of reagent were noted in the useful range of 1-3 nM 3H-succ. Although some limited sample weighing or protein determination must be made for each batch of 3H-labeled glands, this method avoids massive tube weighings and provides the convenience of double label counting with a highly reproducible method for normalizing data.

The ability of an HSV strain to initiate zosteriform spread correlates with its neuroinvasive disease potential

The requirements for disease development in the mouse epidermal scarification-zosteriform model of HSV infection are likely to parallel those required for primary HSV disease of humans. HSV-1 strains, which are neuroinvasive in the mouse footpad model of HSV encephalitis, caused local site lesions within 3 days and secondary zosteriform lesions along the dermatome within approximately 5 days. HSV-1 strains, which are not neuroinvasive, failed to progress to zosteriform lesion development and local site lesions were mild or absent. Relative differences in the rate and extent of zosteriform lesion development paralleled the behavior of the viruses in the mouse footpad model of neuroinvasion. In conclusion, the viral properties which are important for neuroinvasiveness appear to also determine the ability of an HSV strain to cause zosteriform disease.

Characterization of the inhibitory effect of PEG-lipid conjugates on the intracellular delivery of plasmid and antisense DNA mediated by cationic lipid liposomes

Poly(ethylene glycol)-lipid (PEG-lipid) conjugates are widely used in the field of liposomal drug delivery to provide a polymer coat that can confer favorable pharmacokinetic characteristics on particles in the circulation. More recently these lipids have been employed as an essential component in the self-assembly of cationic and neutral lipids with polynucleic acids to form small, stable lipid/DNA complexes that exhibit long circulation times in vivo and accumulate at sites of disease. However, the presence of a steric barrier lipid might be expected to inhibit the transfection activity of lipid/DNA complexes by reducing particle-membrane contact. In this study we examine what effect varying the size of the hydrophobic anchor and hydrophilic head group of PEG-lipids has on both gene and antisense delivery into cells in culture. Lipid/DNA complexes were made using unilamellar vesicles composed of 5 mole% PEG-lipids in combination with equimolar dioleoylphosphatidylethanolamine and the cationic lipid dioleyldimethylammonium chloride. Using HeLa and HepG2 cells we show that under the conditions employed PEG-lipids had a minimal effect on the binding and subsequent endocytosis of lipid/DNA complexes but they severely inhibited active gene transfer and the endosomal release of antisense oligodeoxynucleotides into the cytoplasm. Decreasing the size of the hydrophobic anchor or the size of the grafted hydrophilic PEG moiety enhanced DNA transfer by the complexes.

Comparison of fluorescence, (31)P NMR, and (7)Li NMR spectroscopic methods for investigating Li(+)/Mg(2+) competition for biomolecules

The biochemical action of lithium in the treatment of manic-depressive illness is still unknown. One hypothesis is that Li(+) competes for Mg(2+)-binding sites in biomolecules. We report here our studies on metal ion competition by three distinct methods: fluorescence, (31)P NMR, and (7)Li NMR spectroscopy, using ATP as a model ligand. By fluorescence spectroscopy, we used the dye, furaptra, by measuring the increases in Mg(2+) levels in an ATP solution as Li(+) levels were increased in the solution. This increase in Mg(2+) levels was indicated by increases in the fluorescence intensity ratio (335/370) of furaptra. By (31)P NMR spectroscopy, this competition was demonstrated by changes in the (31)P NMR spectrum of ATP. The Li(+)/Mg(2+) competition was indicated by predictable changes in the separation between the alpha and beta resonances of the phosphates of ATP. For (7)Li NMR spectroscopy, spin-lattice relaxation measurements were used, which provided free Li(+) concentrations that could be used for determining the free Mg(2+) values in ATP solutions. The values of the free Mg(2+) concentrations obtained by all three methods were in good agreement. The fluorescence and (7)Li NMR methods, however, proved to be more sensitive to low concentrations of Li(+) than the (31)P NMR method.

Competition between Li+ and Mg2+ in neuroblastoma SH-SY5Y cells: a fluorescence and 31P NMR study

Because Mg2+ and Li+ ions have similar chemical properties, we have hypothesized that Li+/Mg2+ competition for Mg2+ binding sites is the molecular basis for the therapeutic action of lithium in manic-depressive illness. By fluorescence spectroscopy with furaptra-loaded cells, the free intracellular Mg2+ concentration within the intact neuroblastoma cells was found to increase from 0. 39 +/- 0.04 mM to 0.60 +/- 0.04 mM during a 40-min Li+ incubation in which the total intracellular Li+ concentration increased from 0 to 5.5 mM. Our fluorescence microscopy observations of Li+-free and Li+-loaded cells also indicate an increase in free Mg2+ concentration upon Li+ incubation. By 31P NMR, the free intracellular Mg2+ concentrations for Li+-free cells was 0.35 +/- 0. 03 mM and 0.80 +/- 0.04 mM for Li+-loaded cells (final total intracellular Li+ concentration of 16 mM). If a Li+/Mg2+ competition mechanism is present in neuroblastoma cells, an increase in the total intracellular Li+ concentration is expected to result in an increase in the free intracellular Mg2+ concentration, because Li+ displaces Mg2+ from its binding sites within the nerve cell. The fluorescence spectroscopy, fluorescence microscopy, and 31P NMR spectroscopy studies presented here have shown this to be the case.

Nucleotide metabolism by gastric glands and H(+)-K(+)-ATPase-enriched membranes

alpha-Toxin-permeabilized gastric glands represent a functional model in which acid secretion can be elicited by either adenosine 3',5'-cyclic monophosphate (cAMP) or ATP, with proven morphological and functional transition between resting and secretory states [X. Yao, S. M. Karam, M. Ramilo, Q. Rong, A. Thibodeau, and J. G. Forte. Am. J. Physiol. 271 (Cell Physiol. 40): C61-C73, 1996.] In this study we use alpha-toxin-permeabilized rabbit gastric glands to study energy metabolism and the interplay between nucleotides to support acid secretion, as indicated by the accumulation of aminopyrine (AP). When permeabilized glands were treated with a phosphodiesterase inhibitor, the secretory response to cAMP was inhibited, whereas the secretory response to ATP was potentiated. This implied that 1) ATP provided support not only as an energy source but also as substrate for adenylate cyclase, 2) activation of acid secretion by cAMP needed ATP, and 3) ATP and cAMP exchanged rapidly inside parietal cells. To address these issues, we tested the action of adenine nucleotides in the presence and absence of oxidizable substrates. All adenine nucleotides, including AMP, ADP, ATP, and cAMP, could individually enhance the glandular AP accumulation in the presence of substrates, whereas only a high concentration of ATP (5 mM) was able to support secretory activity in substrate-free buffer. Moreover, ATP could maintain 75-80% of maximal secretory activity in phosphate-free buffer; cAMP alone could not support secretion in phosphate-free buffer. In glands and in H(+)-K(+)-adenosinetriphosphatase-rich gastric microsomes, we showed the operation of adenylate kinase, creatine kinase, and ATP/ADP exchange activities. These enzymes, together with endogenous adenylate cyclase and phosphodiesterase, provide the recycling of nucleotides essential for the viability of alpha-toxin-permeabilized gastric glands and imply the importance of nucleotide recycling for energy metabolism in intact parietal cells.

State of actin in gastric parietal cells

Remodeling of the apical membrane-cytoskeleton has been suggested to occur when gastric parietal cells are stimulated to secrete HCl. The present experiments assayed the relative amounts of F-actin and G-actin in gastric glands and parietal cells, as well as the changes in the state of actin on stimulation. Glands and cells were treated with a Nonidet P-40 extraction buffer for separation into detergent-soluble (supernatant) and detergent-insoluble (pellet) pools. Two actin assays were used to quantitate actin the deoxyribonuclease I binding assay to measure G-actin and F-actin content in the two pools and a simple Western blot assay to quantitate the relative amount of actin in the pools. Functional secretory responsiveness was assayed by aminopyrine accumulation. About 5% of the total parietal cell protein is actin, with about 90% of the actin present as F-actin. Stimulation of acid secretion resulted in no measurable change in the relative amounts of G-actin and cytoskeletal F-actin. Treatment of gastric glands with cytochalasin D inhibited acid secretion and resulted in a decrease in F-actin and an increase in G-actin. No inhibition of parietal cell secretion was observed when phalloidin was used to stabilize actin filaments. These data are consistent with the hypothesis that microfilamentous actin is essential for membrane recruitment underlying parietal cell secretion. Although the experiments do not eliminate the importance of rapid exchange between G- and F-actin for the secretory process, the parietal cell maintains actin in a highly polymerized state, and no measurable changes in the steady-state ratio of G-actin to F-actin are associated with stimulation to secrete acid.

Stimulation of gastric acid secretion by cAMP in a novel alpha-toxin-permeabilized gland model

It is generally believed that histamine-stimulated gastric acid secretion involves a transient elevation of intracellular Ca2+ and the adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) cascade through phosphorylation, whose actions ultimately effect the fusion of H(+)-K(+)-adenosinetriphosphatase (ATPase)-containing vesicles to the apical plasma membrane of parietal cells. To dissect the signaling events underlying gastric acid secretion, we have developed a permeabilized gastric gland model using Staphylococcus alpha-toxin. The advantage of this model is its ability to retain cytosolic components that are required for the secretory machinery. Here we show that acid secretion in alpha-toxin-permeabilized glands is a cAMP-dependent process, reaching a maximal stimulation at 100 microM cAMP. The cAMP-elicited acid secretion, as monitored by the accumulation of the weak base aminopyrine (AP), required functional mitochondria or exogenously supplied ATP. Maximal stimulation elicited by cAMP for AP uptake by permeabilized glands was 51-85% of intact glands. Moreover, secretory activity was potentiated by 0.1 mM ATP. The recruitment of H(+)-K(+)-ATPase-rich tubulovesicles into the apical plasma membrane was measured using biochemical and morphological assays, thus validating the cell activation processes in response to cAMP. From this permeabilized model, [gamma-32P]ATP was used to directly phosphorylate target proteins. A number of proteins whose phosphorylation-dephosphorylation is specifically modulated by cAMP were found. These studies establish the first permeabilized gland model in which the resting-to-secreting transition can be triggered and show that cAMP-mediated phosphorylation is correlated with secretory activity.

Competition between Li+ and Mg2+ for the phosphate groups in the human erythrocyte membrane and ATP: an NMR and fluorescence study

We investigated the mechanism of competition between Li+ and Mg2+ in Li(+)-loaded human red blood cells (RBCs) by making 7Li and 31P NMR and fluorescence measurements. We used 7Li NMR relaxation times to probe Li+ binding to the human RBC membrane and ATP; an increase in Mg2+ concentration caused an increase in both 7Li T1 and T2 values in packed Li(+)-loaded RBCs, in suspensions of Li(+)-loaded RBC ghosts, in suspensions of Li(+)-containing RBC membrane, and in aqueous solutions of ATP, indicating competition between Li+ and Mg2+ for binding sites in the membrane and ATP. We found that increasing concentrations of either Li+ or Mg2+ in the presence of human RBC membrane caused an increase in the 31P NMR chemical shift anisotropy parameter, which describes the observed axially symmetric powder pattern, indicating metal ion binding to the phosphate groups in the membrane. Competition between Li+ and Mg2+ for phosphate groups in ATP and in the RBC membrane was also observed by both fluorescence measurements and 31P NMR spectroscopy at low temperature. The ratio of the stoichiometric binding constants of Mg2+ to Li+ to the RBC membrane was approximately 20; the ratio of the conditional binding constants in the presence of a free intracellular ATP concentration of 0.2 mM was approximately 4, indicating that Li+ competes for approximately 20% of the Mg(2+)-binding sites in the RBC membrane. Our results indicate that, regardless of the spectroscopic method used, Li+ competes with Mg2+ for phosphate groups in both ATP and the RBC membrane; the extent of metal ion competition for the phosphate head groups of the phospholipids in the RBC membrane is enhanced by the presence of ATP. Competition between Li+ and Mg2+ for anionic phospholipids or Mg(2+)-activated proteins present in cell membranes may constitute the basis of a general molecular mechanism for Li+ action in human tissues.

7Li NMR relaxation study of Li+ binding in human erythrocytes

We used 7Li NMR spin-lattice (T1) and spin-spin (T2) relaxation time measurements to investigate the binding of Li+ in human red blood cell (RBC) suspensions. In RBCs containing 1.4 mM Li+, the intracellular 7Li NMR T2 relaxation value (0.30 +/- 0.03 s) was much smaller than the corresponding T1 value (6.0 +/- 0.1 s), yielding a ratio of T1 to T2 of 20. For 1.5 mM LiCl solutions whose viscosities were adjusted to 5 cP with glycerol, the values of the T1/T2 ratios were as follows: 49 for unsealed RBC membrane (2.0 mg of protein/mL); 4.4 for spectrin (1.9 mg/mL); 1.5 for 5.4 mM 2,3-bisphosphoglycerate (BPG); 2.2 for 2.7 mM carbonmonoxyhemoglobin (COHb); 1.6 for 2.0 mM ATP; and 1.2 for a 50/50% (v/v) glycerol-water mixture. Intracellular viscosity and the electric field gradients experienced by Li+ when traversing the spectrin-actin network therefore are not responsible for the large values of the T1/T2 ratios observed in Li(+)-loaded RBCs. We conclude that the RBC membrane is the major Li+ binding site in Li(+)-loaded RBCs (Kb = 215 +/- 36 M-1) and that the binding of Li+ to COHb, BPG, spectrin-actin, or ATP is weak. Partially relaxed 7Li NMR spectra of Li(+)-containing RBC membrane suspensions indicated the presence of two relaxation components, one broad and one narrow.(ABSTRACT TRUNCATED AT 250 WORDS)

[The increase in endocytosis of mouse skeletal muscle after denervation and the proliferation of satellite cells]

The relationship between increase of endocytosis and proliferation of satellite cells in mouse skeletal muscle was studied by biochemical and culture methods in vitro. The results indicated that: (1) 4 d or 6 d after denervation, increase of endocytosis and proliferation of satellite cells in denervated muscle were induced. (2) Actinomycin D inhibited activation of satellite cells and endocytosis in normal muscle. (3) While in denervated muscle, actinomycin D inhibited proliferation of satellite cells as well as increase of endocytosis, but could not prevent muscle atrophy after denervation. These results imply that proliferation of satellite cells and increase of endocytosis in the muscle may concur to the appearance of some factors after denervation, or increase in endocytosis is a mere result of proliferation of satellite cells.

Reinvestigation of the transmembrane difference in 7Li NMR T1 values in Li(+)-loaded human erythrocyte suspensions

In contrast to the findings in a recent study (R. P. Gullapalli, R. M. Hawk, R. A. Komoroski, Magn. Reson. Med. 20, 240 (1991)), we found that, even at high hematocrits, the T1 values for extracellular 7Li were at least three times longer than those for intracellular Li+. We conclude that a transmembrane difference in T1 values can be used for separate observation of intracellular and extracellular Li+ in human red blood cell suspensions.