Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 51
Filter
1.
Psychol Health ; : 1-18, 2022 Feb 14.
Article in English | MEDLINE | ID: mdl-35156467

ABSTRACT

OBJECTIVE: This study applied the theory of reasoned goal pursuit (TRGP) in predicting physical activity among Australian undergraduate students, providing the first empirical test of the model.Methods: The research comprised an elicitation study (N = 25; MAge= 25.76, SDAge= 11.33, 20 female, 5 male) to identify readily accessible procurement and approval goal beliefs and behavioural, normative, and control beliefs; and, a two-wave prospective online survey study (N = 109; MAge = 21.88, SDAge = 7.04, 63 female, 46 male) to test the tenets of the TRGP in relation to meeting World Health Organization physical activity guidelines during the COVID-19 pandemic among first year university students.Results: A linear PLS-SEM model displayed good fit-to-data, predicting 38%, 74%, and 48% of the variance in motivation, intention, and physical activity, respectively. The model supported the majority of hypothesised pattern of effects among theory constructs; in particular, the proposition that beliefs corresponding to procurement and approval goals would be more consequential to people's motivation and, thus, their intentions and behaviour, than other behavioural and normative beliefs, respectively.Conclusions: Results lend support for the TRGP and sets the agenda for future research to systematically test the proposed direct, indirect, and moderation effects for different health behaviours, populations, and contexts.Supplemental data for this article is available online at https://doi.org/10.1080/08870446.2022.2026946 .

2.
Br J Anaesth ; 112(1): 171-2, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24318702
3.
Rev Sci Instrum ; 83(10): 10E110, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23126932

ABSTRACT

Close to an x-ray filter's K-edge the transmission depends strongly on the photon energy. For a few atom pairs, the K-edge of one is only a few tens of eV higher than a K-line energy of another, so that a small change in the line's energy becomes a measurable change in intensity behind such a matching filter. Lutetium's K-edge is ≃27 eV above iridium's Kα(2) line, ≃63.287 keV for cold Ir. A Lu filter reduces this line's intensity by ≃10 % when it is emitted by a plasma, indicating an ionization shift Δε≃10±1 eV.

4.
Br J Anaesth ; 102(6): 768-74, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19398453

ABSTRACT

BACKGROUND: With the proliferation of practice guidelines in anaesthesia comes the possibility that anaesthetists may, during the course of their work, commit 'violations' (actions that are not intended to cause harm to patients, but that deviate from guidelines). These may have a long-term impact on patient safety, and so there is a need to understand what makes anaesthetists decide to follow or deviate from guidelines. METHODS: A questionnaire on the use of guidelines was completed by 629 College Fellows. This presented three anaesthetic scenarios, each of which involved a deviation from a guideline, and asked respondents to rate their beliefs about the likely outcome of the violation, the level of social approval they would have for violating, the amount of control they would have over violating, and the practice of their peers with regard to violating. RESULTS: In all three scenarios, beliefs about the outcome of violating and the amount of control over violating predicted respondents' self-reported likelihood that they would commit the violation. In two scenarios, beliefs about the practice of peers predicted violating. Level of social approval predicted violating in one scenario only. CONCLUSIONS: Anaesthetists' decisions to follow or deviate from guidelines are influenced by the beliefs they hold about the consequences of their actions, the direct or indirect influence of others, and the presence of factors that encourage or facilitate particular courses of action.


Subject(s)
Anesthesia/standards , Anesthesiology/standards , Attitude of Health Personnel , Guideline Adherence/statistics & numerical data , Motivation , Practice Guidelines as Topic , Adult , Aged , Decision Making , Female , Humans , Male , Medical Staff, Hospital/psychology , Medical Staff, Hospital/standards , Middle Aged , United Kingdom
5.
Rev Sci Instrum ; 79(10): 10E306, 2008 Oct.
Article in English | MEDLINE | ID: mdl-19044468

ABSTRACT

A vacuum-voltmeter (VVM) was fielded on the Saturn pulsed power generator during a series of argon gas-puff Z-pinch shots. Time-resolved voltage and separately measured load current are used to determine several dynamic properties as the load implodes, namely, the inductance, L(t), net energy coupled to the load, E(coupled)(t), and the load radius, r(t). The VVM is a two-stage voltage divider, designed to operate at voltages up to 2 MV. The VVM is presently being modified to operate at voltages up to 6 MV for eventual use on the Z generator.

6.
Rev Sci Instrum ; 79(10): 10E717, 2008 Oct.
Article in English | MEDLINE | ID: mdl-19044535

ABSTRACT

The distribution of argon gas injected by a 12-cm-diameter triple-shell nozzle was characterized using both planar, laser-induced fluorescence (PLIF) and high-sensitivity interferometry. PLIF is used to measure the density distribution at a given time by detecting fluorescence from an acetone tracer added to the gas. Interferometry involves making time-dependent, line-integrated gas density measurements at a series of chordal locations that are then Abel inverted to obtain the gas density distribution. Measurements were made on nominally identical nozzles later used for gas-puff Z-pinch experiments on the Saturn pulsed-power generator. Significant differences in the mass distributions obtained by the two techniques are presented and discussed, along with the strengths and weaknesses of each method.

7.
Br J Anaesth ; 100(3): 333-43, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18238839

ABSTRACT

BACKGROUND: Despite a growing recognition of the role of human error in anaesthesia, it remains unclear what should be done to mitigate its effects. We addressed this issue by using task analysis to create a systematic description of the behaviours that are involved during anaesthesia, which can be used as a framework for promoting good practice and highlight areas of concern. METHODS: The task steps involved in preparing and delivering anaesthesia were identified using hierarchical task analysis (HTA). The systematic human error reduction and prediction approach (SHERPA) was then used to identify potential human errors at each task step and suggest ways of preventing these errors. RESULTS: The number and type of behaviours involved vary according to the 'phase' of anaesthesia, with tasks in the induction room, including induction of anaesthesia itself, being the most demanding. Errors during preoperative planning and perioperative maintenance could be avoided by measures to support information handling and decision-making. Errors during machine checking, induction, and emergence could be reduced by streamlining or automating task steps, or by making changes to the physical design of the work environment. CONCLUSIONS: We have demonstrated the value of task analysis in improving anaesthetic practice. Task analysis facilitates the identification of relevant human factors issues and suggests ways in which these issues can be addressed. The output of the task analysis will be of use in focusing future interventions and research in this area.


Subject(s)
Anesthesia/methods , Clinical Competence , Task Performance and Analysis , Anesthesia/standards , Anesthesia Recovery Period , England , Humans , Intraoperative Care/methods , Intraoperative Care/standards , Medical Errors/prevention & control , Preoperative Care/methods , Preoperative Care/standards , Risk Management/methods
8.
Domest Anim Endocrinol ; 34(3): 269-77, 2008 Apr.
Article in English | MEDLINE | ID: mdl-17897805

ABSTRACT

In this study the hypothesis that irreversible glucose loss results in an 'uncoupling' of the somatotrophic axis (increasing plasma GH levels and decreasing plasma IGF-I) was tested. During periods of negative energy balance the somatotrophic axis respond by increasing plasma GH and decreasing plasma IGF-I levels. In turn, elevated GH repartitions nutrient by increasing lipolysis and protein synthesis, and decreases protein degradation. Irreversible glucose loss was induced using sub-cutaneous injections of phloridizin. Seven non-lactating cows were treated with 8g/day phloridizin (PHZ) and seven control animals (CTRL, 0g/day), while being restricted to a diet of 80% maintenance. PHZ treatment increased urinary glucose excretion (P<0.001), resulting in hypoglycemia (P<0.001). As a response to this glucose loss, the PHZ treated animals had elevated plasma NEFA (P<0.005) and BHBA (P<0.001) levels. Average plasma insulin concentrations were not altered with PHZ treatment (P=0.059). Plasma GH was not different between the two groups (P>0.1), whereas plasma IGF-I levels decreased significantly (P<0.001) with PHZ treatment. The decline in plasma IGF-I concentrations was mirrored by a decrease in the abundance of hepatic IGF-I mRNA (P=0.005), in addition the abundance of hepatic mRNA for both growth hormone receptors (GHR(tot) and GHR(1A)) was also decreased (P<0.05). Therefore, the irreversible glucose loss resulted in a partial 'uncoupling' of the somatotrophic axis, as no increase in plasma GH levels occurred although plasma IGF-I levels, hepatic IGF-I mRNA declined, and the abundance of liver GH receptor mRNA declined.


Subject(s)
Adaptation, Physiological/physiology , Cattle Diseases/metabolism , Glucose/metabolism , Malnutrition/veterinary , 3-Hydroxybutyric Acid/blood , Animals , Cattle , Fatty Acids, Nonesterified/blood , Female , Glycosuria/veterinary , Growth Hormone/blood , Hypoglycemia/veterinary , Insulin-Like Growth Factor I/analysis , Insulin-Like Growth Factor I/genetics , Lipolysis/physiology , Liver/chemistry , Malnutrition/metabolism , Phlorhizin/administration & dosage , Protein Biosynthesis/physiology , RNA, Messenger/analysis
9.
Water Sci Technol ; 52(3): 29-36, 2005.
Article in English | MEDLINE | ID: mdl-16206841

ABSTRACT

A Hydrodynamic Vortex Separator (HDVS) has been modelled using Computational Fluid Dynamics (CFD) in order to predict the residence time of the fluid at the overflow and underflow outlets. A technique which was developed for use in Heating, Ventilation and Air Conditioning (HVAC) was used to determine the residence time and the results have been compared with those determined experimentally. It is shown that in using CFD, it is possible to predict the mean residence time of the fluid and to study the response to a pulse injection of tracer. It is also shown that it is possible to apply these techniques to predict the mean survival rate of bacteria in a combined separation and disinfection process.


Subject(s)
Computer Simulation , Disinfection/methods , Bacteria/growth & development , Rheology , Time Factors
10.
Radiat Prot Dosimetry ; 95(4): 295-308, 2001.
Article in English | MEDLINE | ID: mdl-11707028

ABSTRACT

Data on the gastrointestinal absorption of 12 elements have been reviewed. In each case, absorption is expressed as the fraction of the ingested element absorbed to blood, referred to as the f1 value, applying to intakes of unspecified chemical form by average population groups. The level of confidence in individual absorption values has been estimated in terms of lower and upper bounds, A and B, such that there is judged to be roughly a 90% probability that the true central value is no less than A and no greater than B. Ranges are proposed for intakes by adults, 10-year-old children and 3-month-old infants. Uncertainty in f1 values (B/A) ranged from 10% to factors of 100-400. The lowest uncertainties were for the well absorbed elements, H, I and Cs, for which there are good data, and the greatest uncertainties were for less well absorbed elements for which few data are available, particularly Zr and Sb. Ranges were generally wider for children and infants than for adults because of the need to allow for the likelihood of increased absorption with only limited data in support of the proposed values. The largest ranges were for 3-month-old infants, reflective lack of knowledge on the time-course and magnitude of possible increased absorption in the first few months of life. For each age group, ICRP values of absorption tend towards the upper bound of the ranges, indicating a degree of conservatism in th calculation of ingestion dose coefficients. Examination of the effect of the proposed confidence intervals for f1 values on uncertainties in dose coefficients for ingested radionuclides showed that there was no direct relationship. For some radionuclides, uncertainties in effective dose were small despite large uncertainties in f1 values while for others the uncertainties in effective doses approached the corresponding values for uncertainty in f1 values. These differences reflect the relative contributions to effective dose from cumulative activity in the contents of the alimentary tract, which in many cases is insensitive to uncertainties in f1, and cumulative activity of the absorbed radionuclide in systemic tissues, which is proportional to f1. In general, uncertainties in effective close for children and infants exceeded those in adults as a result of greater uncertainties in f1 values for the younger age groups. However, this effect was reduced in some cases by shorter retention times of absorbed nuclides in body tissues and organs.


Subject(s)
Elements , Intestinal Absorption/radiation effects , Radioisotopes/pharmacokinetics , Adult , Child , Dose-Response Relationship, Radiation , Humans , Infant , Radiation Dosage , Radiation Protection , Tissue Distribution
11.
Appl Opt ; 40(15): 2535-45, 2001 May 20.
Article in English | MEDLINE | ID: mdl-18357267

ABSTRACT

We measured the supernumerary spacing parameter of the first- and second-order rainbows of two glass rods, each having an approximately elliptical cross section, as a function of the rod's rotation angle. We attribute large fluctuations in the supernumerary spacing parameter to small local inhomogeneities in the rod's refractive index. The low-pass filtered first-order rainbow experimental data agree with the prediction of ray-tracing-wave-front modeling to within a few percent, and the second-order rainbow data exhibit additional effects that are due to rod nonellipticity.

12.
Teratology ; 61(4): 273-6, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10716745

ABSTRACT

A critical component in the conduct of a prenatal developmental toxicity study is the evaluation of fetal skeletal development. As the developing rodent fetus is typically evaluated at gestation day 20, at a time when ossification of the skeleton is incomplete, a thorough assessment of skeletal development would include both ossified and cartilaginous structures. Current methods to double-stain the fetal skeleton using Alizarin Red S and Alcian Blue are typically described for small sample sizes or using time allotments for each processing step that are unsuitable for industry. In an industrial setting, there is a need for an effective means to double-stain fetal skeletons on a large scale (i.e., hundreds of fetuses simultaneously). This article describes a method used in our laboratory to stain both fetal bone and cartilage using solutions and procedures on an industrial scale.


Subject(s)
Bone and Bones/embryology , Osteogenesis , Alcian Blue , Animals , Anthraquinones , Bone and Bones/cytology , Coloring Agents , Embryonic and Fetal Development , Female , Gestational Age , Male , Pregnancy , Rats , Rats, Sprague-Dawley
13.
Environ Microbiol ; 2(6): 611-9, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11214794

ABSTRACT

A Gram-negative bacterium (CRB5) was isolated from a chromium-contaminated site that was capable of reducing hexavalent chromium to an insoluble precipitate, thereby removing this toxic chromium species from solution. Analysis of the 16S rRNA from the isolate revealed that it was a pseudomonad with high similarity to Pseudomaonas synxantha. CRB5 was tolerant to high concentrations of chromate (500 mg l(-1)) and can reduce Cr(VI) under aerobic and anaerobic conditions. It also exhibited a broad range of reduction efficiencies under minimal nutrient conditions at temperatures between 4 degrees C and 37 degrees C and at pH levels from 4 to 9. As reduction increased, so did total cellular protein, indicating that cell growth was a requirement for reduction. Under low nutrient conditions with CRB5 or when using non-sterile contaminated groundwater from the site, reduction of Cr(VI) was followed by a increase in solution turbidity as a result of the formation of fine-grained Cr(III) precipitates, most probably chromium hydroxide mineral phases such as Cr(OH)3. Chromium adsorption and precipitation, as observed by transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM/EDS), revealed that the surfaces of the cells were uniformly stained with bound Cr(III) and amorphous precipitates (as determined by selected area electron diffraction; SAED). A mass balance of chromium in a batch bioreactor revealed that up to 30% of the total Cr was as settable precipitates or bound to cells.


Subject(s)
Arsenates/metabolism , Chromium/metabolism , Copper/metabolism , Pseudomonas/isolation & purification , Soil Microbiology , Soil Pollutants/metabolism , Biodegradation, Environmental , Biomass , Bioreactors , Hydrogen-Ion Concentration , Microscopy, Electron , Oxidation-Reduction , Pseudomonas/metabolism , Pseudomonas/ultrastructure , Spectrometry, X-Ray Emission , Temperature
15.
Biotechnol Bioeng ; 64(5): 527-44, 1999 Sep 05.
Article in English | MEDLINE | ID: mdl-10404233

ABSTRACT

A series of 23 neutral, anionic, and zwitterionic surfactants were tested at a concentration of 0.1% wt/vol for their influence on attachment of a Mycobacterium sp. to cellulose acetate (CA) and polyamide (PA) reverse osmosis (RO) membranes. Four cell attachment bioassays were used: (1) semiconcurrent addition of surfactant and bacteria to RO coupons (standard assay); (2) surfactant pretreatment of RO membranes (membrane pretreatment assay); (3) surfactant treatment of adsorbed cells (detachment assay); and (4) surfactant pretreatment of mycobacteria (cell pretreatment assay). Seventeen surfactants inhibited attachment to PA membranes, whereas 15 inhibited attachment to CA in standard assays and, in 13 cases, the same surfactant inhibited attachment to both PA and CA. Despite greater cell attachment to PA than CA, surfactants were typically more effective in the former membrane system. More surfactants were effective in impairing cell attachment than in promoting detachment and a number enhanced attachment in membrane pretreatment assays, suggesting surface modification of RO membranes. Cell pretreatment inhibited attachment to CA membranes, suggesting the bacterial surface was also a target for detergent activity. Multivariate regression and cluster analyses indicated that critical micellar concentration (CMC) was positively correlated with Mycobacterium attachment in CA and PA standard assays. Surfactant dipole moment and octanol/water partitioning (LogP) also contributed to detergent activity in the PA system, whereas dipole moment, molecular topology (i.e., connectivity indices), and charge properties influenced activity in the CA system. Influential variables in membrane pretreatment assays included the LogP, topology indices, and charge properties, whereas CMC played a diminished role. Surfactant dipole moment was most influential in CA membrane detachment assays. Increasing system ionic strength by LiBr addition strengthened inhibition of cell attachment to CA membranes by dodecylbenzene sulfonic acid (DBSA) and promoted DBSA adsorption to CA surfaces as indicated by attenuated total reflection Fourier-transform infrared spectrometry. Results indicate that inhibition of bacterial attachment to RO membranes may be maximized by manipulating surfactant molecular structure to optimize surface adsorption behavior.


Subject(s)
Bacterial Adhesion/drug effects , Mycobacterium/drug effects , Surface-Active Agents/pharmacology , Cellulose/analogs & derivatives , Cluster Analysis , Membranes, Artificial , Microscopy, Atomic Force , Mycobacterium/cytology , Nylons , Osmosis , Spectroscopy, Fourier Transform Infrared , Structure-Activity Relationship , Surface Properties , Surface-Active Agents/chemistry
16.
Blood ; 90(9): 3603-12, 1997 Nov 01.
Article in English | MEDLINE | ID: mdl-9345044

ABSTRACT

The immune system of patients infected with human immunodeficiency virus (HIV) is in a state of chronic activation; however, the nature of HIV-related immune activation is unknown. As normal T-cell activation involves early tyrosine phosphorylation induced by the T-cell antigen receptor-associated src-family protein tyrosine kinase p59(fyn(T)) (Fyn), we examined a potential role for this kinase in HIV-related immune dysfunction. We determined the relative specific kinase activity of Fyn in lysates of peripheral blood mononuclear cells from 47 normal control individuals tested negative for HIV-1 and -2, human T-cell lymphotropic virus Type I, hepatitis B virus (HBV), hepatitis C virus (HCV), and syphilis; 14 asymptomatic HIV-infected patients having near-normal CD4+ T-cell counts (350 to 980 CD4+ cells/microL); 4 patients with symptomatic acquired immunodeficiency syndrome (AIDS) (<30 CD4+ cells/microL); 13 patients having chronic infection with HBV (6 patients) or HCV (7 patients); and 6 patients with systemic lupus erythematosis (SLE). All patients with asymptomatic HIV disease were shown to have a profound increase (mean increase of 19-fold; range threefold to 56-fold increase; p = 1.33 x 10(-9)) in the relative specific kinase activity of Fyn compared to uninfected controls or patients with hepatitis or SLE. In contrast, patients with AIDS had an Fyn-specific kinase activity that was much less affected (mean increase of threefold; range onefold to sevenfold increase; p = 1.30 x 10(-5)). It was further shown that HIV infection affects the Fyn-specific kinase activity in CD8+-enriched cells, suggesting abnormal Fyn activity in both CD8+ as well as CD4+ T lymphocytes. Initial results implicate a role for the CSK protein tyrosine kinase as responsible for the abnormal Fyn kinase activity observed in HIV-infected patients. These data indicate early and chronic activation of Fyn as a unique HIV-related effect that has the potential to be diagnostic for early HIV infection and/or may serve as a prognostic indicator for advancement to full-blown AIDS. More importantly, sustained activation of the protein tyrosine kinase associated with T-cell antigen receptor function may result in, or contribute to, the immunopathogenic effects associated with HIV infection.


Subject(s)
HIV Infections/enzymology , HIV Infections/immunology , HIV-1 , Protein-Tyrosine Kinases/immunology , Proto-Oncogene Proteins/immunology , T-Lymphocytes/enzymology , Enzyme Activation/immunology , Humans , Proto-Oncogene Proteins c-fyn , Receptors, Antigen, T-Cell/immunology , T-Lymphocytes/immunology
17.
AIDS ; 10(11): 1191-8, 1996 Sep.
Article in English | MEDLINE | ID: mdl-8883579

ABSTRACT

OBJECTIVE: We examined the effect of HIV infection on src-family protein tyrosine kinase (PTK) activity to determine if alterations in src-family PTK activity could contribute to the HIV-related chronic immune system activation observed in patients infected with HIV. METHODS: Jurkat, a CD4+ human T lymphocyte cell line was infected with HIV IIIB. Kinase activity was determined by in vitro immune complex kinase assays using antibodies specific for the src-family PTKs, p56lck, p59fyn and p60c-src expressed in T lymphocytes. PTK protein and total phosphotyrosine levels were assessed by Western blotting. The role of the gp120-CD4-Lck interaction in HIV-related PTK activation was determined using gp 120-treated Jurkat cells and HIV-infection of JCaM 1.6 cells, a Jurkat-derived cell line that lacks p56lck. RESULTS: Cells infected with HIV for 24 h exhibited increased levels of total tyrosine phosphorylation and enhanced src-family PTK activity without altered levels of expression of src-family kinases. The activity of Lck and Fyn was enhanced within 30 min of infection. HIV-related src-family PTK activation was not a function of the gp120-CD4-Lck interaction and occurred in the presence of 10 mmol/l zidovudine indicating that reverse transcriptase and activation of the HIV genome is not required. CONCLUSIONS: HIV-related activation of src-family PTK is a response of the cell to early stages of the virus life cycle, possibly either membrane fusion or viral uncoating. These results indicate that endogenous src-family PTKs may play a role in HIV-related immune activation and dysfunction. Moreover, activation of src-family PTK may be a mechanism used by the virus to facilitate some aspect of its own life cycle.


Subject(s)
HIV-1/physiology , src-Family Kinases/metabolism , Catalysis , Enzyme Activation , HIV Envelope Protein gp120/metabolism , HIV Reverse Transcriptase/metabolism , Humans , Jurkat Cells , Kinetics , Phosphotyrosine/metabolism
19.
Glia ; 17(3): 225-36, 1996 Jul.
Article in English | MEDLINE | ID: mdl-8840164

ABSTRACT

Essentially pure (>95%) cultures of microglia were established from neopallia of newborn rats and used for whole-cell patch-clamp recording of electrophysiological properties and for proliferation studies. Two types of cultures were examined: 1) "Primary" cultures were grown in culture medium with serum and used within 3 weeks of isolation; 2) and "Colony-stimulating factor (CSF)-1-stimulated" cultures were derived from 3-week-old "primary" cultures by passaging and culturing them for several weeks longer in the presence of conditioned medium enriched in CSF-1. Microglia in the "primary" cultures expressed: 1) an inwardly rectifying K+ current (Kir) that was inhibited by Ba2+; 2) an outwardly rectifying K+ current (Kv) with many similarities to the cloned Kv1.3 channel of lymphocytes, including block by nanomolar concentrations of charybdotoxin (ChTX) and margatoxin (MgTX); and 3) an outwardly rectifying anion current with time- and voltage-independent gating. The anion current is activated reversibly under cell swelling conditions, i.e., after exposure to a hypo-osmotic bathing medium. The anion channels are highly permeable to Cl-, measurably permeable to gluconate (P(gluconate)/ PCl = 0.34), and blocked by flufenamic acid, 4-nitro-2-(3-phenylpropylamino)- benzoic acid (NPPB), and 6, 7-dichloro-2-cyclopentyl-2, 3-dihydro-2-methyl-1-oxo-1H-inden-5-yl (oxy) acetic acid (IAA-94). Microglia in the "CSF-1-stimulated" cultures expressed Kir and Cl- current, but not Kv current. Proliferation in the latter type of cultures could be slowed by omission of the CSF-1 enriched supernatant for 2 days and stimulated by adding back the conditioned medium. This "CSF-1-stimulated" proliferation was inhibited by Ba2+ (Kir blocker), and the Cl(-)-channel blockers flufenamic acid, NPPB, and IAA-94, whereas the Kv blockers ChTX and MgTX had no effect. Thus, Kir and Cl- channels appear to be necessary for "CSF-1-stimulated" proliferation of rat microglia, and there is no evidence that even a transient activation of Kv is necessary.


Subject(s)
Cell Division/physiology , Chloride Channels/physiology , Microglia/metabolism , Microglia/physiology , Potassium Channels/physiology , Animals , Cells, Cultured , Patch-Clamp Techniques , Rats , Rats, Wistar
20.
Cell Signal ; 8(2): 141-9, 1996 Feb.
Article in English | MEDLINE | ID: mdl-8730516

ABSTRACT

Both large- and small-conductance chloride (Cl-) channels have been found in human T lymphocytes; however, apart from possible roles in mediating regulatory volume decrease, their functions are not understood. We have used patch-clamp electrophysiology, Ca2+ spectrofluorometry, and Western blot assay for phosphotyrosine to investigate the effects of blocking Cl- channels on proliferation and on specific events in the activation of normal human T cells. Four chemically distinct Cl- channel blockers inhibited both the small-conductance Cl- channels and phytohemagglutinin (PHA)-induced lymphocyte proliferation in a similar dose-dependent manner; their order of potency was 5-nitro-2(3-phenylpropylamino)-benzoic acid (NPPB) > 4,4'-diisothiocyano-2,2'-disulfonic acid (DIDS) > flufenamic acid >> IAA-94. The Cl- channel blockers inhibited both the PHA-induced mobilization of Ca2+ and the rapid tyrosine phosphorylation of several polypeptides. Cell proliferation was not rescued by the Ca+ ionophore ionomycin or by addition of exogenous interleukin-2 (IL-2). Moreover, the blockers also inhibited phosphotyrosine expression in IL-2-treated, activated lymphoblasts. Thus, our results support a role for Cl- channels in early, PHA-evoked signalling and in later, II-2-dependent stages of lymphocyte activation and proliferation.


Subject(s)
Chloride Channels/antagonists & inhibitors , Lymphocyte Activation/physiology , Signal Transduction/immunology , T-Lymphocytes/physiology , Blotting, Western , Calcium/physiology , Cell Division/drug effects , Cell Division/immunology , Dose-Response Relationship, Immunologic , Humans , Immunosuppressive Agents/pharmacology , Interleukin-2/pharmacology , Patch-Clamp Techniques , Phosphorylation , Spectrometry, Fluorescence , T-Lymphocytes/chemistry , T-Lymphocytes/cytology , Tyrosine/metabolism
SELECTION OF CITATIONS
SEARCH DETAIL
...