RUVBL1 accelerates tongue squamous cell carcinoma by mediating CRaf/MEK/ERK pathway

RAF/MEK/ERK pathway is frequently activated in tumor. Therefore, this study will investigate the function of RUVBL1 (RAF-binding protein) in tongue squamous cell carcinoma (TSCC). Bioinformatics was performed to identify differentially expressed mRNAs (DE-mRNAs) in TCGA-oral squamous cell carcinoma, GSE13601, and GSE34105 datasets. A total of 672 shared DE-mRNAs were identified in three datasets, and they are regulating metastasis and angiogenesis. Patients with RUVBL1 low expression had high overall survival. Overexpressing RUVBL1 enhanced the viability, wound healing percentage, invasion, sphere formation, angiogenesis, and resistance to cisplatin and 5-fluorouracil in CAL-27 and SCC-4 cells, and the opposite results were obtained by knocking down RUVBL1. Moreover, overexpression of RUVBL1 bolstered tumor growth in vivo. Strikingly, RUVBL1 diminished the phosphorylation of CRAF Ser259, which led to activation of the MEK/ERK pathway. In conclusion, RUVBL1 contributes to the malignant biological behavior of TSCC via activating the CRAF/MEK/ERK pathway. This provides molecular mechanisms and perspectives for targeted therapy of the CRAF/MEK/ERK pathway.

Osteogenically committed hUCMSCs-derived exosomes promote the recovery of critical-sized bone defects with enhanced osteogenic properties

Low viability of seed cells and the concern about biosafety restrict the application of cell-based tissue-engineered bone (TEB). Exosomes that bear similar bioactivities to donor cells display strong stability and low immunogenicity. Human umbilical cord mesenchymal stem cells-derived exosomes (hUCMSCs-Exos) show therapeutic efficacy in various diseases. However, little is known whether hUCMSCs-Exos can be used to construct TEB to repair bone defects. Herein, PM-Exos and OM-Exos were separately harvested from hUCMSCs which were cultured in proliferation medium (PM) or osteogenic induction medium (OM). A series of in-vitro studies were performed to evaluate the bioactivities of human bone marrow mesenchymal stem cells (hBMSCs) when co-cultured with PM-Exos or OM-Exos. Differential microRNAs (miRNAs) between PM-Exos and OM-Exos were sequenced and analyzed. Furthermore, PM-Exos and OM-Exos were incorporated in 3D printed tricalcium phosphate scaffolds to build TEBs for the repair of critical-sized calvarial bone defects in rats. Results showed that PM-Exos and OM-Exos bore similar morphology and size. They expressed representative surface markers of exosomes and could be internalized by hBMSCs to promote cellular migration and proliferation. OM-Exos outweighed PM-Exos in accelerating the osteogenic differentiation of hBMSCs, which might be attributed to the differentially expressed miRNAs. Furthermore, OM-Exos sustainably released from the scaffolds, and the resultant TEB showed a better reparative outcome than that of the PM-Exos group. Our study found that exosomes isolated from osteogenically committed hUCMSCs prominently facilitated the osteogenic differentiation of hBMSCs. TEB grafts functionalized by OM-Exos bear a promising application potential for the repair of large bone defects.

3D printed PCL/β-TCP cross-scale scaffold with high-precision fiber for providing cell growth and forming bones in the pores

Scaffolds prepared by 3D printing are increasingly used in the field of bone tissue repair. However, on traditional 3D printed bone tissue engineering scaffolds, cells can only grow on the fiber surface and form bone. We designed a scaffold with a cross-scale structure of PCL/β-TCP, which contains thick fibers with a diameter of 500 μm printed by FDM. And in the pores of the coarse fiber, the ultra-high precision fine fiber grid with a diameter of about 10 μm is filled by MEW mode. In cell experiments, cells can not only grow on the thick fiber surface of the cross-scale scaffold. At the same time, the mesh structure of fine fibers provides a bridge for cell growth, allowing cells to pass through the pores of thick fibers and grow in the pores and gradually cover the pores of the scaffold. In the osteoinduction experiment, β-TCP in the PCL/β-TCP composite provides Ca²⁺ and PO₄^3- to the scaffold, which effectively promotes the osteogenic differentiation of cells on the scaffold. Compared with traditional scaffolds, the osteogenic performance of cross-scale scaffolds is greatly improved. Not only did bone form on the surface of the scaffold, but also obvious ALP expression and effective calcium precipitation appeared in the pores of the scaffold. This can effectively speed up the repair of bone defects. We believe that the 3D printed PCL/β-TCP cross-scale scaffold with high-precision fibers has great application prospects in the field of bone tissue engineering.

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.

A novel method to improve the osteogenesis capacity of hUCMSCs with dual-directional pre-induction under screened co-culture conditions

OBJECTIVES

Mesenchymal stem cells (MSCs) based therapy for bone regeneration has been regarded as a promising method in the clinic. However, hBMSCs with invasive harvesting process and undesirable proliferation rate hinder the extensive usage. HUCMSCs of easier access and excellent performances provide an alternative for the fabrication of tissue-engineered bone construct. Evidence suggested the osteogenesis ability of hUCMSCs was weaker than that of hBMSCs. To address this issue, a co-culture strategy of osteogenically and angiogenically induced hUCMSCs has been proposed since thorough vascularization facilitates the blood-borne nutrition and oxygen to transport in the scaffold, synergistically expediting the process of ossification.

MATERIALS AND METHODS

Herein, we used osteogenic- and angiogenic-differentiated hUCMSCs for co-culture in screened culture medium to elevate the osteogenic capacity with in vitro studies and finally coupled with 3D TCP scaffold to repair rat's critical-sized calvarial bone defect. By dual-directional induction, hUCMSCs could differentiate into osteoblasts and endothelial cells, respectively. To optimize the co-culture condition, gradient ratios of dual-directional differentiated hUCMSCs co-cultured under different medium were studied to determine the appropriate condition.

RESULTS

It revealed that the osteogenic- and angiogenic-induced hUCMSCs mixed with the ratio of 3:1 co-cultured in the mixed medium of osteogenic induction medium to endothelial cell induction medium of 3:1 possessed more mineralization nodules. Similarly, ALP and osteogenesis/angiogenesis-related genes expressions were relatively higher. Further evidence of bone defect repair with 3D printed TCP of 3:1 group exhibited better restoration outcomes.

CONCLUSIONS

Our work demonstrated a favourable and convenient approach of dual-directional differentiated hUCMSCs co-culture to improve the osteogenesis, establishing a novel way to fabricate tissue-engineered bone graft with 3D TCP for large bone defect augmentation.

Hsa_circRNA_33287 promotes the osteogenic differentiation of maxillary sinus membrane stem cells via miR-214-3p/Runx3

BACKGROUND

Circular RNAs (circRNAs) comprise a novel class of noncoding RNAs that play important roles in a variety of diseases. However, the mechanism by which circRNAs regulate the osteogenic differentiation of maxillary sinus membrane stem cells (MSMSCs) remains largely unclear.

METHODS

Microarray analysis was used to explore the expression profiles of circRNAs during the osteogenic differentiation of normal and BMP2 induced-MSMSCs. CircRNA_33287 was identified by agarose electrophoresis, quantitative real-time PCR (qRT-PCR), and western blotting. The function of circRNA_33287 was assessed by loss- and gain-of-function techniques and Alizarin red staining. Potential miRNA binding sites for circRNA_33287, and the target genes of miR-214-3p, were predicted by using online bioinformatics analysis tools. The relationships among the regulatory roles played by circRNA_33287, miR-214-3p, and Runt-related transcription factor 3 (Runx3), during the osteogenic differentiation of MSMSCs were verified by use of the dual luciferase reporter assay, qRT-PCR, and western blotting techniques, respectively. In addition, the molecular sponge potential of circRNA_33287 for miRNA was assessed via in vivo ectopic bone formation and a histological analysis performed after hematoxylin and eosin staining.

RESULTS

Expression of circRNA_33287 was confirmed to be up-regulated during the osteogenic differentiation of MSMSCS. Overexpression and silencing of circRNA_33287 increased and decreased the expression levels of key markers of osteogenesis, respectively, including Runx2, OSX, and ALP. Furthermore, circRNA_33287 acted as a molecular sponge for miR-214-3p, which regulated Runx3 expression by targeting its 3'UTR. Moreover, circRNA_33287 protected Runx3 from miR-214-3p-mediated suppression. In addition, circRNA_33287 was shown to increase ectopic bone formation in vivo and displayed the strongest ability to stimulate bone formation when co-transfected with a miR-214-3p inhibitor.

CONCLUSION

The novel pathway circRNA_33287/miR-214-3p/Runx3 was found to play a role in regulating the osteoblastic differentiation of MSMSCs in the posterior maxilla.

Long noncoding RNA ANCR suppresses bone formation of periodontal ligament stem cells via sponging miRNA-758

Long noncoding RNAs (lncRNAs) were proposed to be important regulators influencing various differentiation processes. Yet, the molecular mechanisms of lncRNAs governing osteogenic differentiation of Periodontal Ligament Stem Cells (PDLSCs) remain unclear. Here, PDLSCs were isolated from normal periodontal ligament of human (PDL) whereas P-PDLSCs were isolated from periodontitis affected PDL. Quantitative real-time PCR (qRT-PCR) was performed to examine the relative expression level of lncRNA-ANCR and of Osterix (OSX), Alkaline Phosphatase (ALP) as well as Runt-related transcription factor 2 (RUNX2) in PDLSCs. Gain- and loss-of- function experiments was performed to study the role of lncRNA-ANCR. Alizarin Red staining was used to evaluate the function of lncRNA-ANCR and miRNA-758 on osteogenic differentiation. In addition, via dual luciferase reporter assay and RNA immunoprecipitation the microRNA sponge potential of lncRNA-ANCR was assessed. A luciferase reporter assay identified the correlation between miR-758 and Notch2. Our results showed that the expression of ALP, RUNX2 and OSX were increased whereas lncRNA-ANCR was decreased during the process of differentiation in PDLSCs. Overexpression of lncRNA-ANCR decreased the expression of ALP, RUNX2 and OSX as confirmed by Alizarin red staining. Overexpression of lncRNA-ANCR resulted in reduction of the miR-758 expression level. Furthermore, RNA immunoprecipitation proved that lncRNA-ANCR targets miR-758 directly. The results of dual luciferase reporter assay also demonstrated that miR-758 regulated Notch2 expression by targeting 3'-UTR of Notch2. In conclusion, the novel pathway lncRNA-ANCR/miR-758/Notch2 plays an important role in the process of regulating osteogenic differentiation of PDLSCs.

Development and application of a perioral force measurement system for infants with cleft lip and palate

BACKGROUND

Muscles converge or intertweave around the perioral area, and this can be treated with sequential therapy in infants with cleft lip and palate (CLP). The force of perioral muscles has a great influence on maxillary development and morphology. Perioral force in infants with CLP has not been well studied, and accurate and reliable measurement of perioral force in infants remains a challenge. This study aimed to investigate a new way to accurately and reliably measure perioral force in infants with unilateral CLP (UCLP) and explore the change before and after cheiloplasty.

STUDY DESIGN

A perioral force measurement system was developed and applied to measure perioral force at labial frenum area and the commissures on both the normal and the cleft sides of four infants with UCLP before and after cheiloplasty. The results were analyzed using the SPSS 19.0 software.

RESULTS

The perioral force measurement system appears to produce valid results in infants with UCLP. Before cheiloplasty, the perioral force of labial frenum area was 1.79 ± 0.94 g/cm² and that of commissure on the normal and cleft sides was 5.41 ± 1.01 g/cm² and 3.12 ± 1.55 g/cm², respectively (P < 0.05). After cheiloplasty, perioral force of labial frenum area was 12.73 ± 3.51 g/cm² and that of commissure on the normal and cleft sides was 7.64 ± 1.64 g/cm² and 7.27 ± 1.89 g/cm², respectively (P > 0.05).

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.

Investigation of multipotent postnatal stem cells from human maxillary sinus membrane

Maxillary sinus membrane (MSM) elevation is a common surgical technique for increasing bone height in the posterior maxilla prior to dental implant placement. However, the biological nature of bone regeneration in MSM remains largely unidentified. In this study, MSM tissue was obtained from 16 individuals during orthognathic surgery and used to isolate MSM stem cells (MSMSCs) by single-colony selection and STRO-1 cell sorting. The cell characteristics in terms of colony-forming ability, cell surface antigens, multi-differentiation potential and in vivo implantation were all evaluated. It was found that MSMSCs were of mesenchymal origin and positive for mesenchymal stem cell (MSC) markers such as STRO-1, CD146, CD29 and CD44; furthermore, under defined culture conditions, MSMSCs were able to form mineral deposits and differentiate into adipocytes and chondrocytes. When transplanted into immunocompromised rodents, MSMSCs showed the capacity to generate bone-like tissue and, importantly, maintain their MSC characteristics after in vivo implantation. These findings provide cellular and molecular evidence that MSM contains stem cells that show functional potential in bone regeneration for dental implant.

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.

Treatment of a subtype of trigeminal neuralgia with descending palatine neurotomy in the pterygopalatine fossa via the greater palatine foramen-pterygopalatine canal approach

PURPOSE

To discuss an effective surgical treatment of a subtype of trigeminal neuralgia with descending palatine neuralgia of the maxillary division.

METHOD

Nine patients, who suffered from trigeminal neuralgia with descending palatine neuralgia of the maxillary division, received neurotomy and avulsion of the descending palatine nerve in the pterygopalatine fossa via the greater palatine foramen-pterygopalatine canal approach. Seven of the patients had a recurrence of descending palatine neuralgia after they received treatment of maxillary neuralgia with neurotomy and avulsion of the infraorbital nerve; two patients were diagnosed with descending palatine neuralgia of the maxillary division in our department. Postoperative follow-up was conducted.

RESULTS

Pain in the palate disappeared; all patients felt numb and paresthetic in the area innervated by the trigeminal nerve, with no pain. During the 3-36 months of follow-up, no recurrence occurred.

CONCLUSIONS

Descending palatine neurotomy in the pterygopalatine fossa via the greater palatine foramen-pterygopalatine canal approach is a simple, safe and effective way to treat a subtype of trigeminal neuralgia--descending palatine neuralgia.

Pterygopalatine fossa segment neurectomy of maxillary nerve through maxillary sinus route in treating trigeminal neuralgia

PURPOSE

To explore an effective surgical treatment for pain in the distribution area of the maxillary branch of trigeminal nerve (TN).

MATERIALS AND METHODS

Twenty-six patients with pain in the distribution of the maxillary branch of TN were followed up after they had undergone pterygopalatine fossa segment neurectomy of maxillary nerve through maxillary sinus route.

RESULTS

In all cases, the pain initially resolved after operation, with anaesthesia or paraesthesia in the operated side of the maxillary nerve-distributed area. After a mean follow-up period of 24 (range 3-36) months, 19 (73.08%) of the 26 patients had an excellent response, 5 (19.23%) had a good response, 2 (7.69%) had a fair response, and none (0%) had a poor response. One patient had a recurrence with palatal pain 3 months after the operation.

CONCLUSIONS

The maxillary sinus route can provide a clear vision for sectioning of the maxillary nerve. This new surgical technique has proven to be safe and effective. It provides another option for the weak elderly who are intolerant of craniotomy or patients who have contraindications for craniotomy when radiofrequency thermocoagulation (RFT) and percutaneous glycerol neurolysis (PGR) treatment is not possible.

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.