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At least 1,279 records · Page 71Linked to original sources
PubMed1989

Forskolin sensitizes parathyroid hormone-induced cyclic AMP response, but not the bone resorptive effect, in mouse calvarial bones.

The effect of forskolin on parathyroid hormone (PTH) stimulated bone resorption, as assessed in vitro by the release of 45Ca from prelabelled neonatal mouse calvarial bones, and cyclic AMP formation in mouse calvarial bones and osteoblast-like cells was investigated. Much higher concentrations (100-300-times) of PTH were required to stimulate cyclic AMP accumulation than to stimulate mineral mobilization in murine calvarial bones. PTH, in the absence of phosphodiesterase inhibitor, stimulated cyclic AMP formation in mouse calvarial bones at and above concentrations of 3-10 nmol/l with EC50 at 10-15 nmol/l. In the presence of forskolin (1 or 10 mumol/l) the minimal concentration required to obtain a cyclic AMP response to PTH was decreased by a factor of 30-100 and the EC50 value was decreased to 1-2 nmol/l. Similar results were seen in osteoblast-enriched cells. In addition, the magnitude of the PTH-induced cyclic AMP response was substantially potentiated by forskolin, both in calvarial bones and in isolated osteoblasts. Forskolin, in the absence of PTH, stimulated cyclic AMP levels in mouse calvaria at and above 1 mumol/l. In the presence of PTH, the response to forskolin was potentiated over the whole dose-response curve with apparent EC50 value at 1-2 mumol/l of forskolin. Forskolin (1 mumol/l) did not affect the magnitude of the 45Ca release response to PTH in 24 or 48 h cultures. In 96 h cultures, forskolin, in an additive manner, potentiated the effect of PTH on calcium mobilization. These results show that forskolin, in mouse calvarial bones and in isolated osteoblasts, in addition to directly stimulating cyclic AMP, can enhance receptor-mediated activation of adenylate cyclase. The finding that forskolin did not synergistically potentiate PTH-induced bone resorption suggests that there is no simple relationship between PTH-induced cyclic AMP formation and stimulation of bone resorption.

Animals↗
PubMed2006

Metal mobility during in situ chemical oxidation of TCE by KMnO4.

The potential for trace-metal contamination of aquifers as a side effect of In Situ Chemical Oxidation (ISCO) of chlorinated solvent contamination by KMnO(4) is investigated with column experiments. The experiments investigate metal mobility during in situ chemical oxidation of TCE by KMnO(4) under conditions where pH, flow rate, KMnO(4), TCE, and trace-metal concentrations were controlled. During ISCO, the injection of MnO(4) creates oxidizing conditions, and acidity released by the reactions causes a tendency toward low pH in aquifers. In order to evaluate the role of pH buffering on metal mobility, duplicate columns were constructed, one packed with pure silica sand, and one with a mixture of silica sand and calcite. Aqueous solutions of TCE and KMnO(4) (with 1 mg/L Cu, Pb, Zn, Mo, Ni, and Cr(VI)) were allowed to mix at the inlet to the columns. After the completion of the experiments, samples of Mn oxide were removed from the columns and analyzed by analytical scanning and transmission electron microscopy. In order to relate the results of the laboratory experiments to field settings, the analyses of Mn-oxide samples from the lab experiments were compared to samples of Mn oxide collected from a field-scale chemical-oxidation experiment that were also analyzed by analytical electron microscopy as well as time-of-flight secondary-ion mass spectroscopy. The pH ranged from 2.40 in the silica sand column to 6.25 in the calcite-containing column. The data indicate that aqueous Mo, Pb, Cu and Ni concentrations are attenuated almost completely within the columns. In contrast, Zn concentrations are not significantly attenuated and Cr(VI) is transported conservatively. The results indicate that within the range 2.40 to 6.25, metal mobility is not affected by pH. Comparison of analyses of Mn-oxide from the lab and field demonstrate that a variety of metals are sequestered from solution by Mn oxide.

Geologic Sediments↗
PubMed2005

PKI-based secure mobile access to electronic health services and data.

Recent research works examine the potential employment of public-key cryptography schemes in e-health environments. In such systems, where a Public Key Infrastructure (PKI) is established beforehand, Attribute Certificates (ACs) and public key enabled protocols like TLS, can provide the appropriate mechanisms to effectively support authentication, authorization and confidentiality services. In other words, mutual trust and secure communications between all the stakeholders, namely physicians, patients and e-health service providers, can be successfully established and maintained. Furthermore, as the recently introduced mobile devices with access to computer-based patient record systems are expanding, the need of physicians and nurses to interact increasingly with such systems arises. Considering public key infrastructure requirements for mobile online health networks, this paper discusses the potential use of Attribute Certificates (ACs) in an anticipated trust model. Typical trust interactions among doctors, patients and e-health providers are presented, indicating that resourceful security mechanisms and trust control can be obtained and implemented. The application of attribute certificates to support medical mobile service provision along with the utilization of the de-facto TLS protocol to offer competent confidentiality and authorization services is also presented and evaluated through experimentation, using both the 802.11 WLAN and General Packet Radio Service (GPRS) networks.

Certification↗
PubMed1997

Phosphatidic acid elicits calcium mobilization and actin polymerization through a tyrosine kinase-dependent process in human neutrophils: a mechanism for induction of chemotaxis.

Phospholipids mediate important effects as extracellular messengers in diverse biological systems. We investigated the effects of phosphatidic acid, a biologically active phospholipid potentially involved in the inflammatory process, on calcium mobilization and actin polymerization in human neutrophils and correlated these effects with induction of chemotactic migration. Intermediate-chain length phosphatidic acid (DiC10-PA) induced a biphasic increase in intracellular Ca2+ characterized by a rapid rise commencing immediately upon addition of stimulus followed by a secondary increase which, unlike the initial response, was eliminated by chelation of extracellular Ca2+. Neither of these responses were induced by C10-lysophosphatidic acid or diacylglycerol. The tyrosine kinase inhibitor herbimycin-A (5-10 microg/ml) completely blunted the initial but not the delayed response effected by DiC10-PA. Long-chain phosphatidic acid (DiC18:1) induced only an initial rapid increase in intracellular Ca2+ and this response was similarly markedly attenuated by herbimycin-A. Among several physiologically relevant phospholipids, only phosphatidic acid was able to induce Ca2+ mobilization; phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol -- used individually or in mixed liposomes -- were without effect. Phosphatidic acid conferred calcium-mobilizing activity upon inactive liposome preparations and phosphatidic acid-enriched cellular plasma membranes possessed similar calcium-mobilizing activity. Both DiC10-PA and DiC18:1-PA induced actin polymerization in neutrophils at rates which mirrored the influence of each agent on Ca2+ mobilization. Herbimycin-A blunted the initial increase in actin polymerization effected by phosphatidic acid but had no effect on the delayed, EGTA-sensitive phase. DiC10-PA and DiC18:1-PA also induced neutrophil migration along a concentration gradient. Phospholipids that failed to induce a calcium transient, including phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and phosphatidylinositol, likewise failed to induce either actin polymerization or chemotactic migration. Unlike chemotaxis induced by zymosan-activated human serum, phosphatidate-induced chemotaxis was strongly inhibited by pretreatment of cells with herbimycin-A. Consistent with these observations, phosphatidic acid induced the tyrosine phosphorylation of several proteins as early as 10 s after stimulation. Phosphorylation of two distinct proteins with approximate molecular sizes of 72 and 82 kDa was inhibited by levels of herbimycin A used to effectively inhibit calcium mobilization, actin polymerization and chemotaxis. Thus, in neutrophilic leukocytes, extracellular phosphatidic acid induces a unique tyrosine kinase-based signalling pathway that results in calcium mobilization and actin polymerization. These processes may promote directed cellular migration as a consequence of the interaction of phosphatidic acid with neutrophil plasma membranes.

Actins↗
PubMed2000

Immunobiology of allogeneic peripheral blood mononuclear cells mobilized with granulocyte-colony stimulating factor.

The use of mobilized peripheral blood (PB) stem cells for autologous transplantation initially generated much enthusiasm because of enhanced engraftment in comparison to marrow stem cells and avoidance of general anesthesia for the donor. Its application to the allogeneic setting seemed inevitable. For obvious ethical reasons, allogeneic donors are mobilized with cytokines only, mainly granulocyte colony-stimulating factor (G-CSF). Results from preliminary studies suggest that in comparison to standard bone marrow transplants, outcomes such as engraftment, host-versus-graft reaction, graft-versus-host disease, graft-versus-leukemia and immunological reconstitution may be different. Surprisingly, G-CSF, previously recognized as a late acting lineage-specific factor for neutrophil production, not only disrupts homeostasis between stem cells and their microenvironment, but also induces significant quantitative and qualitative changes in the accessory cell compartment, affecting lymphocytes, monocytes, natural killer, dendritic, and stromal cells. Furthermore, mobilization of huge numbers of non-professional antigen presenting cells (CD34+ stem cells) amplifies the tolerizing potential of PB stem cell grafts. Thus, G-CSF mobilization provides PB transplants with different immunobiologic properties in comparison to standard bone marrow grafts. Whether these immunobiologic differences will lead to better transplant outcomes remains to be shown through much awaited results of large randomized clinical trials.

Bone Marrow Transplantation↗
PubMed1983

[Effects of poly-L-lysine, poly-L-glycine and poly-L-glutamic acid on ANS fluorescence and electrokinetic potential of splenic lymphocytes in the mouse].

The in vivo effect of either poly-L-Lysine, poly-L-Glutamic acid or poly-L-Glycine on mouse spleen cell populations was investigated. The membrane fluorescence changes of activated splenic lymphocytes were studied. Experiments were performed with the hydrophobic fluorescent probe: 1-anilino-8-naphthalene sulphonate (ANS). Kinetic studies further indicated that the course of fluorescence changes may vary considerably depending upon homopolymers. These fluorescence intensity changes would be in direct or inverse relation to the electrokinetic surface potential changes of activated lymphocytes, as assessed by the electrophoretic mobility analysis. It could be concluded that the relation (direct or inverse) between ANS fluorescence and electrokinetic potential depends upon the net electrical charge of the homopolymer used. In further experiments, the determination of the net electrical charge of some tumour antigens could be considered without hard purifications.

Action Potentials↗
PubMed1992

Compensation for mobility inequalities between lanes computed from band signals in on-line fluorescence DNA sequencing.

Among on-line fluorescence DNA sequencing systems, the four-lane method exhibits the potential for reporting an erroneous sequence due to nonuniform mobility of the DNA fragments migrating among the four lanes. This error is manifest in phenomenon commonly called smiling. This paper presents a computational algorithm which compensates for the mobility inequalities between lanes using signal data obtained from the shorter DNA fragments forming the faster migrating bands. The program mainly consists of two routines: (i) calculation of calibration coefficients (mobility ratios between lanes), and (ii) examination of the coefficients by applying them to a later domain of the same signals. Both routines are connected with several feed-back branches for recalculation. Homology analysis of final sequences has shown that the accuracy rate is maximized with this algorithm and any ambiguous result can be assigned to the residual error inherent in the band identification method used.

Algorithms↗
PubMed2000

New method for standardization of electropherograms obtained in capillary zone electrophoresis.

A new method for standardization of electropherograms obtained by capillary zone electrophoresis was proposed, where the migration time axis was replaced by the effective mobility axis. The mobility increase due to temperature increase by Joule heating and the relaxation effect of the potential gradient were eliminated successfully by introducing a temperature coefficient for mobility expression and a delay time, respectively. The precision of the mobility evaluated by the proposed conversion methods was evaluated for a model sample. By using the conversion method, almost the same electropherograms could be obtained even from the electropherograms originally obtained by using different hardware conditions.

Electrophoresis, Capillary↗
PubMed1999

Dynamic cell cycle kinetics of normal CD34+ cells and CD38+/- subsets of haemopoietic progenitor cells in G-CSF-mobilized peripheral blood.

Using a recently developed flow cytometric assay for the simultaneous measurement of cell surface antigens, DNA content and bromodeoxyuridine incorporation, we have for the first time determined the labelling index (LI), the duration of the S-phase (Ts) and the potential doubling time (Tpot) of purified CD34+ cells mobilized by G-CSF from 10 normal donors. Although CD34+ cells were not actively cycling immediately following purification, up to 5% could nevertheless traverse cell cycle without exogenous stimulation during the first 24 h of culture. In addition, it was possible to induce CD34+ cells to enter cycling by stimulation with haemopoietic growth factors (IL-3, IL-6 and SCF), resulting in median Tpot values of 18.2 d at 21 h, 7.7 d at 29 h, and 4.5 d at 37 h. Importantly, stimulation of CD34+ cells was seen almost exclusively within the CD38+ subset (mean Tpot value 2.8 d), whereas CD38- cells were not recruited into cycle (mean Tpot value 35.9 d). In conclusion, although cell cycle entry and progression can easily be induced in differentiated CD34+/CD38+ cells, immature CD34+/CD38- cells will remain dormant in most of the clinical and laboratory stimulation protocols hitherto employed. This assay can be used to obtain detailed cell cycle kinetics in leucocyte subsets in health and disease.

ADP-ribosyl Cyclase↗
PubMed2006

Wear-simulation analysis of rotating-platform mobile-bearing knees.

The wear and wear debris from rotating-platform mobile-bearing knees and fixed-bearing knees were compared in knee joint-simulator studies. The wear rate of the fixed-bearing knees was found to increase as the kinematics were increased because of an increase in internal-external rotation and an increase in anterorposterior (AP) translation. The wear rate of the rotating-platform mobile-bearing knees was found to be significantly lower than that of the fixed-bearing knees. The rotating-platform mobile-bearing knee was able to decouple the complex kinematics to pure rotation at the inferior tibial articulating surface and linear flexion-extension and AP sliding at the superior femoral articulating interface, substantially reducing cross-shear and wear. No difference was found in the wear debris between the rotating-platform and fixed-bearing knees. This resulted in a substantially reduced functional biological activity or osteolytic potential for the rotating-platform mobile-bearing knees due to the lower wear rates.

Knee Prosthesis↗
PubMed2000

Biomechanical investigations on chondromalacia of the knee after meniscal flap lesion and partial meniscal resection: an experimental model.

Meniscal tears and resections may cause chondral lesions of the knee. To eliminate muscular control during investigation of this problem, we designed a biomechanical setup based on a knee-joint simulator, ensuring physiological, free-motion mobility of the joint. Fresh human knee specimens with intact cartilage were exposed to loads to 2,000 N at a frequency of 0.85 Hz during 48 hours of gait. After a preliminary test series, 18 specimens were divided into three groups: group I was tested with unchanged meniscal status, group II with arthroscopically induced mobile flap tears at the posterior horns of the menisci, and group III after partial resection of the posterior horns. Motion patterns between the groups changed after as little as a few hours due to increased translation in group III. Macroscopic and histological examination and scanning electron microscopy revealed severe chondromalacic changes after meniscal resection. We conclude that meniscal resection-however partial-may have considerable joint-damaging potential if muscle control is lacking whereas mobile flap tears maintain stability. Our findings might explain the differences in clinical reports on cartilage status after partial meniscal resection. This study underlines the importance of muscle training when active stabilisation of the knee is reduced after partial meniscal resection.

Adult↗
PubMedDate not supplied

Career mobility in nursing for paramedics.

A largely untapped source of potential nurses are paramedics and emergency technicians. The author reports the results of a testing program to assess advanced placement options for paramedics. Interestingly, the paramedics scored higher in seven of nine categories compared with the scores of sophomore nursing students.

Adult↗
PubMed1989

Changes induced in adrenergic lipolysis by the administration of diethylstilboestrol, oestradiol and clomiphene.

The authors studied changes in adrenergic lipolysis in the epididymal adipose tissue of rats to which diethylstilboestrol and oestradiol combined with the anti-oestrogen clomiphene were administered. The maximum lipid-mobilizing effect of isoprenaline was increased not only by subcutaneously administered diethylstilboestrol, but also by the highest dose of the antioestrogen clomiphene used (p.o., 200 micrograms.kg-1 b.w.). Under the given experimental conditions, with 4 1/2 h incubation of adipose tissue, clomiphene was also effective when added in vitro. Its own oestrogenic effect probably stimulated the lipid-mobilizing action of isoprenaline. On combining the administration of increasing doses of clomiphene (p.o., 1-5 days) with a constant dose of oestradiol (200 micrograms.kg-1, s.c. on the 8th day, i.e. 24 h before the actual experiment), changes in isoprenaline lipolysis depended on the dose of clomiphene. In low doses clomiphene inhibited the stimulating effect of subsequently administered oestradiol on isoprenaline-induced lipolysis, but in large doses (100 and 200 micrograms.kg-1 daily) it potentiated, together with oestradiol, the lipid-mobilizing effect of isoprenaline. The results show that the non-steroid oestrogen diethylstilboestrol and the antioestrogen clomiphene may be included among the hormones capable of altering the response of adipose tissue to sympathomimetics (isoprenaline). We attribute the fact that clomiphene acted either as an antagonist or as an agonist of oestradiol to its combined oestrogenic and anti-oestrogenic effects.

Adipose Tissue↗
PubMed2005

Expression and functional evaluation of transient receptor potential channel 4 in bovine corneal endothelial cells.

We previously found that activation of purinergic receptors mobilizes Ca2+ and enhances bicarbonate transport in bovine corneal endothelial cells (BCEC). Since transient receptor potential channel 4 (TRPC) has been reported to be a candidate for capacitative calcium entry (CCE) and receptor operated calcium entry (ROC), we examined the expression of TRPC4 and evaluated the potential involvement of TRPC4 in CCE or ROC in BCEC. The C-terminus of TRPC4 was fused into the glutathione S-transferase (GST) expression vector. The fusion protein GST-TRPC4c was induced in bacteria and purified by affinity chromatography. An antibody was raised in rabbit by using the purified GST-TRPC4c antigen. In Western blotting, the TRPC4 antibody recognized the fusion protein while the pre-immune IgG did not. The TRPC4 antibody recognized a band at around 80 kD for membrane proteins from both the fresh and cultured BCEC. The pre-immune IgG could not detect bands at the same size. Incubation with the TRPC4c antigen abolished the 80 kD band. Immunofluorescence using the TRPC4 antibody stained both fresh and cultured BCEC, while pre-immune IgG did not. RNAi knocked down the expression of TRPC4 in cultured BCEC. Ca2+ entry induced by the purinergic receptor agonist ATP, was increased in TRPC4-siRNA transfected cells compared with the scrambled siRNA control, while Ca2+ entry induced by store depletion through blocking the endoplasmic reticulum Ca2+ pump, did not differ between the siRNA and scrambled siRNA-treated cells. Taken together, these results show that TRPC4 protein is expressed in the bovine corneal endothelial cells and may be a negative regulator in ROC stimulated by purinergic activation, but not by store depletion itself.

Animals↗
PubMed2004

Admission and discharge mobility of frail hospitalized older adults.

Functional decline during hospitalization is an important clinical problem with potential longlasting undesirable outcomes in frail elders. However, little is known about the change in mobility during hospitalization and the association with discharge status. A Mobility Classification Tool has been developed that categorizes progression of patients' in-hospital mobility using a 5-point scale. The validity and clinical usefulness of this tool was evaluated in a sample of 60 frail older adults hospitalized for medical illness. The tool allows nurses to assess, quantify, and communicate mobility levels and changes in mobility more accurately.

Academic Medical Centers↗
PubMed2002

Reversible phosphatidylserine expression on blood granulocytes related to membrane perturbation but not DNA strand breaks.

Exposure of phosphatidylserine (PS) on the outer leaflet of the cell membrane is recognized as an early indicator of programmed cell death (apoptosis) in plant and mammalian cells. Currently, there is no literature describing that PS expression on the surface of white blood cells is reversible. We found that a hypotonic 0.2% NaCl or NH(4)Cl lysing solution used to separate white blood cells from red blood cells induced a reversible PS expression on the cell surface of granulocytes and monocytes but not lymphocytes. This reversible PS expression was associated with change of plasma membrane potential but not degranulation-associated membrane mobilization or DNA fragmentation. In contrast, TNF-alpha induced an irreversible PS expression, associated with apoptotic DNA fragmentation shown on gel electrophoresis. The fact that hypotonic shock induced a reversible PS expression on granulocytes, and TNF-alpha induced an irreversible PS expression associated with apoptotic DNA fragmentation indicate the new insight that expression of PS on the outer cell surface does not always represent cell apoptosis. Also, the reversible PS expression was associated with altered plasma-membrane potential but not DNA strand breaks, indicating that early PS expression may be related to the membrane perturbation but not directly related to DNA fragmentation in certain types of cells.

Adult↗
PubMed1996

The leucine zipper may induce electrophoretic mobility anomalies without DNA bending.

Numerous proteins bend DNA upon binding, a phenomenon of potential significance for regulation of gene expression and chromatin. DNA bending is commonly predicted from the presence of electrophoretic mobility anomalies in protein-DNA complexes. However, as compared with electrophoretic methods, several DNA binding oncoprotein families do not display comparable evidence of DNA bends in x-ray structural studies. Herein, circularization kinetics and affinity measurements with prebent DNA templates were employed to assess bending and DNA structural preferences for Max and other basic helix-loop-helix/leucine zipper proteins. In this way, proteins in the Myc/Max basic helix-loop-helix/ leucine zipper family were found not to bend DNA in solution but to actually stabilize DNA in an unbent configuration that resists circularization. The mobility anomaly was found to be induced by the leucine zipper protein motif, rather than structural distortions of DNA. Thus rigid protein domain structures may induce anomalous electrophoretic mobility. Moreover, the energetic preference of non-DNA bending proteins for unbent templates suggests mechanisms whereby chromatin structure may regulate transcription.

Binding Sites↗