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1.
Workplace Health Saf ; 61(3): 99-101, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23452129

ABSTRACT

Filtering facepiece respirators (FFRs) and surgical masks may appear similar in design, but are quite different. When worker protection from inhalation hazards is necessary, a respirator, not a surgical mask, must be selected. For FFRs to protect wearers, however, wearers must be trained in wearing and using them properly, determine they fit by being fit tested, perform a user seal check each time FFRs are put on, and be medically evaluated to ensure they are physically able to wear FFRs while working.


Subject(s)
Masks , Occupational Exposure/prevention & control , Occupational Health , Respiratory Protective Devices , Humans
2.
J Occup Environ Hyg ; 9(10): 563-71, 2012.
Article in English | MEDLINE | ID: mdl-22924959

ABSTRACT

Fit is an important but difficult-to-predict feature of respirator performance. This study examined a new approach to measuring respirator performance using two continuous direct-reading particle-counting instruments in a simulated health care workplace. A pilot test was conducted with eight experienced health care professionals who passed a traditional quantitative fit test before performing three randomized 10-min health care scenarios (patient assessment [PA], IV treatment [IV], and wound care [WC]). Two TSI Portacount Plus (Model 8020) with N95 Companion (Model 8095) instruments were used to continuously measure 1-sec ambient particle concentrations inside and outside the respirator facepiece. A simulated workplace protection factor (SWPF) was calculated by dividing outside by inside concentrations. Data were log transformed and examined using analysis of variance (ANOVA) between subjects, scenario types, and scenario order. The GM SWPF for the eight subjects, three scenarios per subject, ranged from 172 to 1073 (GSD 1.7 to 3.5) and was significantly different for each subject. A multi-way analysis of variance showed no difference between the three scenario types (PA, IV, WC). There were differences by the order in which scenarios were performed: the third scenario SWPF was significantly different and higher than that of the first and second scenarios. All subjects passed the initial quantitative fit test with a fit factor of at least 100. Five subjects had fit factors greater than 200 and GM scenario SWPFs greater than 400. Three participants with initial fit factors less than 200 had GM scenario SWPFs ranging from 132 to 326. This pilot test demonstrates that it is possible to evaluate instantaneous respirator fit using two quantitative fit test instruments in a simulated health care environment. Results suggest that an initial fit test may be predictive of fit during simulated tasks and that one scenario may be adequate for measuring a simulated workplace protection factor. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a video for subject D activities overlaid with simulated workplace protection factor data.].


Subject(s)
Masks/standards , Respiratory Protective Devices/standards , Adolescent , Adult , Aged , Air Pollutants, Occupational/analysis , Analysis of Variance , Equipment Safety , Feasibility Studies , Female , Health Personnel , Humans , Male , Middle Aged , Particulate Matter/analysis , Pilot Projects , Young Adult
3.
J Biol Chem ; 287(10): 7279-88, 2012 Mar 02.
Article in English | MEDLINE | ID: mdl-22184123

ABSTRACT

TRPV1 and TRPV3 are two heat-sensitive ion channels activated at distinct temperature ranges perceived by human as hot and warm, respectively. Compounds eliciting human sensations of heat or warmth can also potently activate these channels. In rodents, TRPV3 is expressed predominantly in skin keratinocytes, whereas in humans TRPV1 and TRPV3 are co-expressed in sensory neurons of dorsal root ganglia and trigeminal ganglion and are known to form heteromeric channels with distinct single channel conductances as well as sensitivities to TRPV1 activator capsaicin and inhibitor capsazepine. However, how heteromeric TRPV1/TRPV3 channels respond to heat and other stimuli remains unknown. In this study, we examined the behavior of heteromeric TRPV1/TRPV3 channels activated by heat, capsaicin, and voltage. Our results demonstrate that the heteromeric channels exhibit distinct temperature sensitivity, activation threshold, and heat-induced sensitization. Changes in gating properties apparently originate from interactions between TRPV1 and TRPV3 subunits. Our results suggest that heteromeric TRPV1/TRPV3 channels are unique heat sensors that may contribute to the fine-tuning of sensitivity to sensory inputs.


Subject(s)
Ganglia, Spinal/metabolism , Ion Channel Gating/physiology , Sensory Receptor Cells/metabolism , TRPV Cation Channels/metabolism , Thermosensing/physiology , Animals , Capsaicin/analogs & derivatives , Capsaicin/pharmacology , HEK293 Cells , Hot Temperature , Humans , Ion Channel Gating/drug effects , Mice , Sensory System Agents/pharmacology , TRPV Cation Channels/antagonists & inhibitors , TRPV Cation Channels/genetics , TRPV Cation Channels/immunology , Thermosensing/drug effects
4.
Bioorg Med Chem Lett ; 21(19): 5774-7, 2011 Oct 01.
Article in English | MEDLINE | ID: mdl-21875806

ABSTRACT

Excitatory amino acid transporter 2 (EAAT2) is the major glutamate transporter and functions to remove glutamate from synapses. A thiopyridazine derivative has been found to increase EAAT2 protein levels in astrocytes. A structure-activity relationship study revealed that several components of the molecule were required for activity, such as the thioether and pyridazine. Modification of the benzylthioether resulted in several derivatives (7-13, 7-15 and 7-17) that enhanced EAAT2 levels by >6-fold at concentrations < 5 µM after 24h. In addition, one of the derivatives (7-22) enhanced EAAT2 levels 3.5-3.9-fold after 24h with an EC(50) of 0.5 µM.


Subject(s)
Excitatory Amino Acid Transporter 2/agonists , Pyridazines/chemical synthesis , Pyridazines/pharmacology , Astrocytes/drug effects , Astrocytes/metabolism , Biological Transport , Cells, Cultured , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical , Excitatory Amino Acid Transporter 2/metabolism , Glutamates/metabolism , Pyridazines/chemistry , Structure-Activity Relationship
5.
J Biomol Screen ; 15(6): 653-62, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20508255

ABSTRACT

Excitotoxicity has been implicated as the mechanism of neuronal damage resulting from acute insults such as stroke, epilepsy, and trauma, as well as during the progression of adult-onset neurodegenerative disorders such as Alzheimer's disease and amyotrophic lateral sclerosis (ALS). Excitotoxicity is defined as excessive exposure to the neurotransmitter glutamate or overstimulation of its membrane receptors, leading to neuronal injury or death. One potential approach to protect against excitotoxic neuronal damage is enhanced glutamate reuptake. The glial glutamate transporter EAAT2 is the quantitatively dominant glutamate transporter and plays a major role in clearance of glutamate. Expression of EAAT2 protein is highly regulated at the translational level. In an effort to identify compounds that can induce translation of EAAT2 transcripts, a cell-based enzyme-linked immunosorbent assay was developed using a primary astrocyte line stably transfected with a vector designed to identify modulators of EAAT2 translation. This assay was optimized for high-throughput screening, and a library of approximately 140,000 compounds was tested. In the initial screen, 293 compounds were identified as hits. These 293 hits were retested at 3 concentrations, and a total of 61 compounds showed a dose-dependent increase in EAAT2 protein levels. Selected compounds were tested in full 12-point dose-response experiments in the screening assay to assess potency as well as confirmed by Western blot, immunohistochemistry, and glutamate uptake assays to evaluate the localization and function of the elevated EAAT2 protein. These hits provide excellent starting points for developing therapeutic agents to prevent excitotoxicity.


Subject(s)
Excitatory Amino Acid Transporter 2/metabolism , High-Throughput Screening Assays/methods , Neuroglia/metabolism , Neurotoxins/toxicity , Protein Biosynthesis/drug effects , Small Molecule Libraries/analysis , Small Molecule Libraries/pharmacology , 5' Untranslated Regions/genetics , Enzyme-Linked Immunosorbent Assay , Excitatory Amino Acid Transporter 2/genetics , Gene Expression Regulation/drug effects , Humans , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reproducibility of Results
6.
J Biol Chem ; 283(10): 6162-74, 2008 Mar 07.
Article in English | MEDLINE | ID: mdl-18178557

ABSTRACT

Transient receptor potential channels are involved in sensing chemical and physical changes inside and outside of cells. TRPV3 is highly expressed in skin keratinocytes, where it forms a nonselective cation channel activated by hot temperatures in the innocuous and noxious range. The channel has also been implicated in flavor sensation in oral and nasal cavities as well as being a molecular target of some allergens and skin sensitizers. TRPV3 is unique in that its activity is sensitized upon repetitive stimulations. Here we investigated the role of calcium ions in the sensitization of TRPV3 to repetitive stimulations. We show that the sensitization is accompanied by a decrease of Ca(2+)-dependent channel inhibition mediated by calmodulin acting at an N-terminal site (amino acids 108-130) and by an acidic residue (Asp(641)) at the pore loop of TRPV3. These sites also contribute to the voltage dependence of TRPV3. During sensitization, the channel displayed a gradual shift of the voltage dependence to more negative potentials as well as uncoupling from voltage sensing. The initial response to ligand stimulation was increased and sensitization to repetitive stimulations was decreased by increasing the intracellular Ca(2+)-buffering strength, inhibiting calmodulin, or disrupting the calmodulin-binding site. Mutation of Asp(641) to Asn abolished the high affinity extracellular Ca(2+)-mediated inhibition and greatly facilitated the activation of TRPV3. We conclude that Ca(2+) inhibits TRPV3 from both the extracellular and intracellular sides. The inhibition is sequentially reduced, appearing as sensitization to repetitive stimulations.


Subject(s)
Calcium/metabolism , Calmodulin/metabolism , Keratinocytes/metabolism , Skin/metabolism , TRPV Cation Channels/metabolism , Allergens/metabolism , Amino Acid Substitution , Animals , Binding Sites/genetics , Calmodulin/genetics , Cell Line , Hot Temperature , Humans , Keratinocytes/cytology , Mice , Mouth/metabolism , Mutation, Missense , Nasal Cavity/metabolism , Skin/cytology , TRPV Cation Channels/antagonists & inhibitors , TRPV Cation Channels/genetics
7.
Prev Chronic Dis ; 3(2): A42, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16539783

ABSTRACT

INTRODUCTION: Mortality rates are used as global measures of a population's health status and as indicators for public health efforts and medical treatments. Elevated mortality rates among individuals with mental illness have been reported in various studies, but very little focus has been placed on interstate comparisons and congruency of mortality and causes of death among public mental health clients. METHODS: Using age-adjusted death rates, standardized mortality ratios, and years of potential life lost, we compared the mortality of public mental health clients in eight states with the mortality of their state general populations. The data used in our study were submitted by public mental health agencies in eight states (Arizona, Missouri, Oklahoma, Rhode Island, Texas, Utah, Vermont, and Virginia) for 1997 through 2000 during the Sixteen-State Study on Mental Health Performance Measures, a multistate study federally funded by the Center for Mental Health Services in collaboration with the National Association of State Mental Health Program Directors. RESULTS: In all eight states, we found that public mental health clients had a higher relative risk of death than the general populations of their states. Deceased public mental health clients had died at much younger ages and lost decades of potential life when compared with their living cohorts nationwide. Clients with major mental illness diagnoses died at younger ages and lost more years of life than people with non-major mental illness diagnoses. Most mental health clients died of natural causes similar to the leading causes of death found nationwide, including heart disease, cancer, and cerebrovascular, respiratory, and lung diseases. CONCLUSION: Mental health and physical health are intertwined; both types of care should be provided and linked together within health care delivery systems. Research to track mortality and primary care should be increased to provide information for additional action, treatment modification, diagnosis-specific risk, and evidence-based practices.


Subject(s)
Cause of Death , Community Health Services , Mental Disorders/complications , Accidents/statistics & numerical data , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Heart Diseases/complications , Heart Diseases/mortality , Humans , Infant , Longevity , Mental Disorders/mortality , Middle Aged , Suicide/statistics & numerical data , United States
8.
J Cell Physiol ; 208(1): 201-12, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16557504

ABSTRACT

Transient receptor potential vanilloid (TRPV) channels are polymodal detectors of multiple environmental factors, including temperature, pH, and pressure. Inflammatory mediators enhance TRPV function through multiple signaling pathways. The lipoxygenase and epoxygenase products of arachidonic acid (AA) metabolism have been shown to directly activate TRPV1 and TRPV4, respectively. TRPV3 is a thermosensitive channel with an intermediate temperature threshold of 31-39 degrees C. We have previously shown that TRPV3 is activated by 2-aminoethoxydiphenyl borate (2APB). Here we show that AA and other unsaturated fatty acids directly potentiate 2APB-induced responses of TRPV3 expressed in HEK293 cells, Xenopus oocytes, and mouse keratinocytes. The AA-induced potentiation is observed in intracellular Ca2+ measurement, whole-cell and two-electrode voltage clamp studies, as well as single channel recordings of excised inside-out and outside-out patches. The fatty acid-induced potentiation is not blocked by inhibitors of protein kinase C and thus differs from that induced by the kinase. The potentiation does not require AA metabolism but is rather mimicked by non-metabolizable analogs of AA. These results suggest a novel mechanism regulating the TRPV3 response to inflammation, which differs from TRPV1 and TRPV4, and involves a direct action of free fatty acids on the channel.


Subject(s)
Fatty Acids, Unsaturated/pharmacology , TRPV Cation Channels/drug effects , TRPV Cation Channels/physiology , Animals , Arachidonic Acid/pharmacology , Boron Compounds/pharmacology , Calcium/analysis , Cell Line , Cells, Cultured , Electrophysiology , Enzyme Activation/physiology , Humans , Inflammation/physiopathology , Keratinocytes/chemistry , Keratinocytes/drug effects , Keratinocytes/physiology , Kidney/chemistry , Kidney/drug effects , Kidney/embryology , Kidney/physiology , Linoleic Acid/pharmacology , Mice , Oleic Acid/pharmacology , Oleic Acids , Oocytes/chemistry , Oocytes/drug effects , Oocytes/physiology , Patch-Clamp Techniques , Protein Kinase C/antagonists & inhibitors , Protein Kinase C/physiology , Signal Transduction/physiology , TRPV Cation Channels/analysis , Xenopus Proteins/analysis , Xenopus Proteins/physiology
9.
J Biol Chem ; 279(36): 37423-30, 2004 Sep 03.
Article in English | MEDLINE | ID: mdl-15234965

ABSTRACT

Transient receptor potential vanilloid 1 (TRPV1), or vanilloid receptor 1, is the founding member of the vanilloid type of TRP superfamily of nonselective cation channels. TRPV1 is activated by noxious heat, acid, and alkaloid irritants as well as several endogenous ligands and is sensitized by inflammatory factors, thereby serving important functions in detecting noxious stimuli in the sensory system and pathological states in different parts of the body. Whereas numerous studies have been carried out using the rat and human TRPV1 cDNA, the mouse TRPV1 cDNA has not been characterized. Here, we report molecular cloning of two TRPV1 cDNA variants from dorsal root ganglia of C57BL/6 mice. The deduced proteins are designated TRPV1alpha and TRPV1beta and contain 839 and 829 amino acids, respectively. TRPV1beta arises from an alternative intron recognition signal within exon 7 of the trpv1 gene. We found a predominant expression of TRPV1alpha in many tissues and significant expression of TRPV1beta in dorsal root ganglia, skin, stomach, and tongue. When expressed in HEK 293 cells or Xenopus oocytes, TRPV1alpha formed a Ca(2+)-permeable channel activated by ligands known to stimulate TRPV1. TRPV1beta was not functional by itself but its co-expression inhibited the function of TRPV1alpha. Furthermore, although both isoforms were synthesized at a similar rate, less TRPV1beta than TRPV1alpha protein was found in cells and on the cell surface, indicating that the beta isoform is highly unstable. Our data suggest that TRPV1beta is a naturally occurring dominant-negative regulator of the responses of sensory neurons to noxious stimuli.


Subject(s)
Alternative Splicing , Genes, Dominant , Receptors, Drug/genetics , Amino Acid Sequence , Animals , Base Sequence , Cell Line , Cloning, Molecular , DNA Primers , Humans , Mice , Mice, Inbred C57BL , Molecular Sequence Data
10.
J Biol Chem ; 279(34): 35741-8, 2004 Aug 20.
Article in English | MEDLINE | ID: mdl-15194687

ABSTRACT

The transient receptor potential (TRP) superfamily contains a large number of proteins encoding cation permeable channels that are further divided into TRPC (canonical), TRPM (melastatin), and TRPV (vanilloid) subfamilies. Among the six TRPV members, TRPV1, TRPV2, TRPV3, and TRPV4 form heat-activated cation channels, which serve diverse functions ranging from nociception to osmolality regulation. Although chemical activators for TRPV1 and TRPV4 are well documented, those for TRPV2 and TRPV3 are lacking. Here we show that in the absence of other stimuli, 2-aminoethoxydiphenyl borate (2APB) activates TRPV1, TRPV2, and TRPV3, but not TRPV4, TRPV5, and TRPV6 expressed in HEK293 cells. In contrast, 2APB inhibits the activity of TRPC6 and TRPM8 evoked by 1-oleolyl-2-acetyl-sn-glycerol and menthol, respectively. In addition, low levels of 2APB strongly potentiate the effect of capsaicin, protons, and heat on TRPV1 as well as that of heat on TRPV3 expressed in Xenopus oocytes. In dorsal root ganglia neurons, supra-additive stimulations were evoked by 2APB and capsaicin or 2APB and acid. Our data suggest the existence of a common activation mechanism for TRPV1, TRPV2, and TRPV3 that may serve as a therapeutic target for pain management and treatment for diseases caused by hypersensitivity and temperature misregulation.


Subject(s)
Boron Compounds/pharmacology , Calcium Channels/drug effects , Capsaicin/pharmacology , Cation Transport Proteins/agonists , Ion Channels/agonists , Signal Transduction/drug effects , Animals , Calcium/metabolism , Cell Line , Dose-Response Relationship, Drug , Drug Synergism , Ganglia, Spinal/metabolism , Humans , Mice , Neurons/metabolism , Rats , TRPV Cation Channels , Temperature , Xenopus
11.
Biochemistry ; 42(33): 9952-8, 2003 Aug 26.
Article in English | MEDLINE | ID: mdl-12924944

ABSTRACT

Ribosomal protein synthesis in eubacteria and eukaryotic organelles initiates with an N-formylmethionyl-tRNA(i), resulting in N-terminal formylation of all nascent polypeptides. Peptide deformylase (PDF) catalyzes the subsequent removal of the N-terminal formyl group from the majority of bacterial proteins. Deformylation was for a long time thought to be a feature unique to the prokaryotes, making PDF an attractive target for designing novel antibiotics. However, recent genomic sequencing has revealed PDF-like sequences in many eukaryotes, including man. In this work, the cDNA encoding Homo sapiens PDF (HsPDF) has been cloned and a truncated form that lacks the N-terminal 58-amino-acid targeting sequence was overexpressed in Escherichia coli. The recombinant, Co(2+)-substituted protein is catalytically active in deformylating N-formylated peptides, shares many of the properties of bacterial PDF, and is strongly inhibited by specific PDF inhibitors. Expression of HsPDF fused to the enhanced green fluorescence protein in human embryonic kidney cells revealed its location in the mitochondrion. However, HsPDF is much less active than its bacterial counterpart, providing a possible explanation for the apparent lack of deformylation in the mammalian mitochondria. The lower catalytic activity is at least partially due to mutation of a highly conserved residue (Leu-91 in E. coli PDF) in mammalian PDF. PDF inhibitors had no detectable effect on two different human cell lines. These results suggest that HsPDF is likely an evolutional remnant without any functional role in protein formylation/deformylation and validates PDF as an excellent target for antibacterial drug design.


Subject(s)
Amidohydrolases , Aminopeptidases/chemistry , Drug Design , Escherichia coli/enzymology , Amino Acid Sequence , Aminopeptidases/genetics , Aminopeptidases/metabolism , Anti-Bacterial Agents/pharmacology , Cell Division/drug effects , Cells, Cultured , Cloning, Molecular , DNA, Complementary/metabolism , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Green Fluorescent Proteins , Humans , Kidney/enzymology , Kinetics , Leucine/chemistry , Luminescent Proteins/metabolism , Mitochondria/enzymology , Molecular Sequence Data , Mutagenesis, Site-Directed , Peptides/chemistry , Protein Binding , Protein Transport , Recombinant Fusion Proteins/metabolism , Sequence Homology, Amino Acid
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