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1.
BMJ Mil Health ; 2023 Jul 02.
Article in English | MEDLINE | ID: mdl-37400128

ABSTRACT

Advances in technology have improved the ability for real-time communication and enhanced awareness of medically related information on the battlefield. A government off-the-shelf platform, Team Awareness Kit (TAK), may enhance the ability for battlefield healthcare delivery, evacuation, telecommunication, and medical command and control. Integration of TAK into existing medical infrastructure provides a global view of resources, patient movement and direct communication, significantly reducing the 'fog of war' as it relates to battlefield injury and evacuation. Rapid integration and adoption are technically feasible with minimal resource investment. This technology can be rapidly scaled for the increasingly interconnected world of healthcare delivery.

2.
PLoS One ; 17(8): e0273370, 2022.
Article in English | MEDLINE | ID: mdl-36007072

ABSTRACT

Data substantiating the optimal patient body temperature during cooling procedures in cardiac operations are currently unavailable. To explore the optimal temperature strategy, we examined the association between temperature management and survival among patients during cardiopulmonary bypass assisted coronary artery bypass grafting (CABG) procedures on 30-days and 5-year postoperative survival. Adult patients (n = 5,672, 23.6% female and mean (SD) age of 66 (10) years) operated between 1997 and 2015 were included, with continuous measured intraoperative nasopharyngeal temperatures. The association between mortality and patient characteristics, laboratory parameters, the lowest intraoperative plateau temperature and intraoperative cooling/rewarming rates were examined by multivariate Cox regression analysis. Machine learning-based cluster analysis was used to identify patient subgroups based on pre-cooling parameters and explore whether specific subgroups benefitted from a particular temperature management. Mild hypothermia (32-35°C) was independently associated with improved 30-days and 5-year survival compared to patients in other temperature categories regardless of operation year. 30 days and 5-year survival were 98% and 88% in the mild hypothermia group, whereas it amounted 93% and 80% in the severe hypothermia (<30°C). Normothermia (35-37°C) showed the lowest survival after 30 days and 5 years amounting 93% and 72%, respectively. Cluster analysis identified 8 distinct patient subgroups principally defined by gender, age, kidney function and weight. The full cohort and all patient subgroups displayed the highest survival at a temperature of 32°C. Given these associations, further prospective randomized controlled trials are needed to ascertain optimal patient temperatures during CPB.


Subject(s)
Hypothermia, Induced , Hypothermia , Adult , Aged , Body Temperature , Cardiopulmonary Bypass/methods , Cohort Studies , Coronary Artery Bypass/adverse effects , Female , Humans , Hypothermia/etiology , Hypothermia, Induced/methods , Male
3.
Acta Psychiatr Scand ; 142(6): 486-495, 2020 12.
Article in English | MEDLINE | ID: mdl-32961606

ABSTRACT

OBJECTIVE: Physical exercise may serve as a protective factor for posttraumatic stress disorder (PTSD), but little is known about whether physical exercise is associated with PTSD in population-based samples of military veterans. METHODS: We analyzed cross-sectional data on the relation between self-reported physical exercise frequency and the prevalence of probable PTSD in a nationally representative sample of 2832 U.S. military veterans who participated in the National Health and Resilience in Veterans Study. RESULTS: A "U-shaped" association best explained the relation between self-reported exercise frequency and the prevalence of probable PTSD. Compared to veterans without probable PTSD, those with probable PTSD were nearly twice as likely to report no weekly exercise (52.3% vs. 29.3%) or daily (7 days/week) exercise (15.2% vs. 8.5%) and were nearly half as likely to report exercising a median of 3.5 days/week (32.6% vs. 62.1%). No exercise was associated with greater severity of emotional numbing and lower severity of anxious arousal symptoms, while daily exercise was associated with greater severity of re-experiencing symptoms. CONCLUSIONS: Results of this study suggest a "U-shaped" association between self-reported exercise frequency and the prevalence of probable PTSD among U.S. veterans. Veterans with probable PTSD were more likely than those without probable PTSD to report not exercising at all or exercising every day and were less likely to report exercising 1-6 days per week. Clinical implications of these findings are discussed.


Subject(s)
Exercise , Stress Disorders, Post-Traumatic/epidemiology , Veterans/psychology , Adult , Aged , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Prevalence , Self Report , Stress Disorders, Post-Traumatic/psychology , United States/epidemiology , Veterans/statistics & numerical data
4.
AAPS PharmSciTech ; 20(2): 40, 2019 Jan 04.
Article in English | MEDLINE | ID: mdl-30610396

ABSTRACT

Polymer strip film is a promising dosage form for oral delivery of poorly water-soluble drugs. Drying is an important step in the production of polymer strip films with significant effects on critical quality attributes (CQAs). In this study, a custom-made batch drying setup was used to study convective drying kinetics of wet polymer strip films loaded with dry-coated micronized griseofulvin (GF) at various drying conditions. A rate-based semi-empirical model was formulated and parameters were estimated by integral method of analysis using a coupled optimizer-ordinary differential equation solver. Despite its simplicity with three parameters, the model could fit the experimental data very well for all drying conditions, which enabled us to examine the effects of air velocity, temperature, and initial wet film thickness on drying kinetics quantitatively. The modeling results clearly delineate a drying mechanism with constant-rate and falling-rate periods. One set of kinetic parameter estimates reasonably predicted the drying kinetics for two different wet film thicknesses in the selected process conditions, which demonstrates the predictive capability of the model. After reporting the limitations of the semi-empirical model, upon future modification and refinement, its potential use in drying process development and process control was highlighted.


Subject(s)
Desiccation/methods , Drug Delivery Systems , Polymers/chemistry , Griseofulvin/chemistry , Kinetics , Solubility , Temperature
6.
Arch Environ Contam Toxicol ; 70(2): 311-20, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26498942

ABSTRACT

Selenium (Se) is an essential micronutrient that can be found at toxic concentrations in surface waters contaminated by runoff from agriculture and coal mining. Zebrafish (Danio rerio) embryos were exposed to aqueous Se in the form of selenate, selenite, and l-selenomethionine (SeMet) in an attempt to determine if oxidative stress plays a role in selenium embryo toxicity. Selenate and selenite exposure did not induce embryo deformities (lordosis and craniofacial malformation). l-selenomethionine, however, induced significantly higher deformity rates at 100 µg/L compared with controls. SeMet exposure induced a dose-dependent increase in the catalytic subunit of glutamate-cysteine ligase (gclc) and reached an 11.7-fold increase at 100 µg/L. SeMet exposure also reduced concentrations of TGSH, RGSH, and the TGSH:GSSG ratio. Pretreatment with 100 µM N-acetylcysteine significantly reduced deformities in the zebrafish embryos secondarily treated with 400 µg/L SeMet from approximately 50­10 % as well as rescued all three of the significant glutathione level differences seen with SeMet alone. Selenite exposure induced a 6.6-fold increase in expression of the glutathione-S-transferase pi class 2 (gstp2) gene, which is involved in xenobiotic transformation and possibly oxidative stress. These results suggest that aqueous exposure to SeMet can induce significant embryonic teratogenesis in zebrafish that are at least partially attributed to oxidative stress.


Subject(s)
Embryo, Nonmammalian/drug effects , Selenomethionine/toxicity , Water Pollutants, Chemical/toxicity , Zebrafish/embryology , Acetylcysteine/metabolism , Animals , Glutamate-Cysteine Ligase/metabolism , Glutathione/metabolism , Teratogenesis
7.
Mar Pollut Bull ; 58(8): 1178-1186, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19394971

ABSTRACT

The present study aimed to establish potential indicators of fish farming pollution in muddy substrate, by means of meiofauna, and to test whether the effect of the fish farm is more important to determine the meiofauna community than the seasonal environmental conditions. Sampling was performed in spring, after several months of light feeding, and in summer, at high food supply. Samples were collected in three directions at various distances from the floating cages. Harpacticoid copepods and kinorhynchs, whose abundance decreased under the cages, were put forward as indicator taxa. However, harpacticoid copepods were sensitive to fish farm only, while kinorhynchs showed responsiveness to fish farm and to seasonal environmental conditions. Total meiofauna density was dependent on season sensu stricto. The nMDS clearly showed a 'cage community' and 'control community' in both sampling occasions; therefore it is a good tool for impact assessment.


Subject(s)
Biodiversity , Fisheries , Seasons , Animals , Chlorophyll , Population Density , Salinity , Seawater/chemistry
8.
Am J Physiol Gastrointest Liver Physiol ; 293(3): G532-43, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17569740

ABSTRACT

The gastric parietal cell is responsible for the secretion of HCl into the lumen of the stomach mainly due to stimulation by histamine via the cAMP pathway. However, the participation of several other receptors and pathways have been discovered to influence both stimulation and inhibition of acid secretion (e.g., cholinergic). Here we examine the role of phosphoinositide 3-kinase (PI3K) in the modulation of acid secretion. Treatment of isolated gastric glands and parietal cells with the PI3K inhibitor, LY294002 (LY), potentiated acid secretion in response to histamine to nearly the maximal secretion obtained with histamine plus phosphodiesterase inhibitors. As cAMP levels were elevated in response to histamine plus LY, but other means of elevating cAMP (e.g., forskolin, dbcAMP) were not influenced by LY, we posited that the effect might require activation of G-protein-coupled histamine H(2) receptors, possibly through the protein kinase B pathway (also known as Akt). Study of downstream effectors of PI3K showed that histaminergic stimulation increased Akt phosphorylation, which in turn was blocked by inhibition of PI3K. Expression studies showed that high expression of active Akt decreased acid secretion, whereas dominant-negative Akt increased acid secretion. Taken together, these data suggest stimulation with histamine increases the activity of PI3K leading to increased activity of Akt and decreased levels of cAMP in the parietal cell.


Subject(s)
Gastric Acid/metabolism , Gastric Mucosa/metabolism , Histamine/metabolism , Parietal Cells, Gastric/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Receptors, Histamine H2/metabolism , Signal Transduction , 1-Methyl-3-isobutylxanthine/pharmacology , Aminopyrine , Androstadienes/pharmacology , Animals , Carbachol/pharmacology , Cell Shape , Cells, Cultured , Cholinergic Agonists/pharmacology , Chromones/pharmacology , Cyclic AMP/metabolism , Dose-Response Relationship, Drug , Epidermal Growth Factor/metabolism , Gastric Mucosa/cytology , Gastric Mucosa/drug effects , Gastric Mucosa/enzymology , Histamine H2 Antagonists/pharmacology , Morpholines/pharmacology , Mutation , Organ Culture Techniques , Parietal Cells, Gastric/drug effects , Parietal Cells, Gastric/enzymology , Phosphodiesterase Inhibitors/pharmacology , Phosphoinositide-3 Kinase Inhibitors , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Pyrimidinones/pharmacology , Rabbits , Receptors, Histamine H2/drug effects , Time Factors , Transduction, Genetic , Wortmannin
9.
J Physiol ; 579(Pt 1): 29-51, 2007 Feb 15.
Article in English | MEDLINE | ID: mdl-17124265

ABSTRACT

This study concerns the properties of neurons carrying signals for colour vision in primates. We investigated the variability of responses of individual parvocellular lateral geniculate neurons of dichromatic and trichromatic marmosets to drifting sinusoidal luminance and chromatic gratings. Response variability was quantified by the cycle-to-cycle variation in Fourier components of the response. Averaged across the population, the variability at low contrasts was greater than predicted by a Poisson process, and at high contrasts the responses were approximately 40% more variable than responses at low contrasts. The contrast-dependent increase in variability was nevertheless below that expected from the increase in firing rate. Variability falls below the Poisson prediction at high contrast, and intrinsic variability of the spike train decreases as contrast increases. Thus, while deeply modulated responses in parvocellular cells have a larger absolute variability than weakly modulated ones, they have a more favourable signal: noise ratio than predicted by a Poisson process. Similar results were obtained from a small sample of magnocellular and koniocellular ('blue-on') neurons. For parvocellular neurons with pronounced colour opponency, chromatic responses were, on average, less variable (10-15%, p<0.01) than luminance responses of equal magnitude. Conversely, non-opponent parvocellular neurons showed the opposite tendency. This is consistent with a supra-additive noise source prior to combination of cone signals. In summary, though variability of parvocellular neurons is largely independent of the way in which they combine cone signals, the noise characteristics of retinal circuitry may augment specialization of parvocellular neurons to signal luminance or chromatic contrast.


Subject(s)
Color Perception/physiology , Geniculate Bodies/physiology , Models, Neurological , Retinal Cone Photoreceptor Cells/physiology , Animals , Callithrix , Contrast Sensitivity/physiology , Electroencephalography , Fourier Analysis , Geniculate Bodies/cytology , Photic Stimulation , Poisson Distribution , Retinal Cone Photoreceptor Cells/cytology , Visual Pathways
10.
Biochemistry ; 43(24): 7924-39, 2004 Jun 22.
Article in English | MEDLINE | ID: mdl-15196037

ABSTRACT

Stimulation of gastric parietal cells results in exocytic recruitment of the proton pump (H(+),K(+)-ATPase) from a pool of intracellular membranes (tubulovesicles) to the apical plasma membrane. We have previously reconstituted a step in this process, the homotypic fusion of tubulovesicles, and shown that they also fuse with liposomes in a protein-dependent manner [Duman, J. G., Singh, G., Lee, G. Y., Machen, T. E., and Forte, J. G. (2002) Traffic 3, 203-17]. Further, the lipid composition of the liposomes affects their ability to undergo fusion with tubulovesicles. In the present study, we investigated the lipid requirements for tubulovesicular membrane fusion using a fluorescent probe relaxation assay as well as transfer of protein between tubulovesicles and liposomes of defined composition. Initially, we tested the ability of tubulovesicles to undergo fusion with a panel of synthetic phosphatidylcholine-based liposomes containing a variety of common membrane lipids of various shapes and charges. We found that anionic lipids such as phosphatidylserine, phosphatidic acid, and phosphoinositides were best able to enhance tubulovesicle-liposome fusion and that they did it in a dose-dependent, apparently saturable manner. Next, we altered the lipid compositions of actual tubulovesicles and observed that addition of anionic lipids was able to enhance tubulovesicle-tubulovesicle fusion in vitro; thus, we hypothesized that the charge imparted by the lipids, per se, was responsible for the enhancement of membrane fusion. Accordingly, addition of negative charges to one of two pools of tubulovesicles in a fusion assay using anionic detergents increased membrane fusion; whereas, addition of positively charged cationic detergent decreased membrane fusion and could be used to back-titrate the anionic effects. Surprisingly, when both pools of fusing membranes were loaded with anionic detergents, fusion was markedly increased. The ability of anionic charges to enhance fusion was diminished as the ionic strength of the fusion medium was increased, suggesting that the mechanism of fusion enhancement depends on the surface charge of the membranes. Finally, the fusion reaction was highly dependent on temperature, and anionic charge appears to lower the activation energy of the fusion reaction. Taken together, these data suggest that (1) tubulovesicular fusion is enhanced by an increase in membrane surface negative charge associated with a lower activation energy and (2) neutralization or reversal of the surface charge prevents tubulovesicular fusion.


Subject(s)
Exocytosis , Membrane Fusion , Animals , Fluorescent Dyes , H(+)-K(+)-Exchanging ATPase/metabolism , H(+)-K(+)-Exchanging ATPase/ultrastructure , Liposomes , Microscopy, Electron , Rabbits , Stomach/enzymology
11.
J Microsc ; 212(Pt 1): 13-20, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14516357

ABSTRACT

We describe a procedure for high-pressure freezing (HPF) of cultured cells using the HPF aluminium planchettes as a substrate. Cells are either grown directly on planchettes covered with Matrigel or allowed to attach to poly-l-lysine-coated planchettes. This method allows for rapid transfer of the cells into the HPF and minimizes physical and physiological trauma to the cells. Furthermore, the yield of well-frozen cells approaches 100% for every cell type we have tried so far. In this report, we show well-preserved ultrastructure in mitotic and interphase HeLa cells, isolated gastric parietal cells and isolated gastric glands. Immunogold labelling of H+/K+-ATPase is shown in parietal cells of isolated gastric glands embedded in LR White resin. The aluminium planchettes appear to have little effect on cell physiology, as demonstrated by the fact that parietal cells cultured for 24-28 h on the planchettes retain their responsiveness to stimulation with histamine.


Subject(s)
Cell Adhesion , Cryopreservation/instrumentation , Cryopreservation/methods , Aluminum , Animals , Cells, Cultured , Freeze Substitution , Gastric Mucosa/cytology , Gastric Mucosa/ultrastructure , H(+)-K(+)-Exchanging ATPase/metabolism , HeLa Cells , Humans , Lysine/metabolism , Microscopy, Electron , Parietal Cells, Gastric/ultrastructure , Pressure , Rabbits
12.
J Microsc ; 208(Pt 3): 158-66, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12460447

ABSTRACT

A newly designated procedure for high-pressure freezing of primary culture cells provided excellent ultrastructure of rabbit gastric parietal cells. The isolated parietal cells were cultivated on Matrigel-coated aluminium plates for conventional subsequential cryoimmobilization by high-pressure freezing. The ultrastructure of different organelles (Golgi apparatus, mitochondria, multivesicular bodies, etc.) was well preserved compared to conventional chemical fixation. In detail, actin filaments were clearly shown within the microvilli and the subapical cytoplasm. Another striking finding on the cytoskeleton system is the abundance of microtubules among the tubulovesicles. Interestingly, some microtubules appeared to be associating with tubulovesicles. A large number of electron-dense coated pits and vesicles were observed around the apical membrane vacuoles in cimetidine-treated resting parietal cells, consistent with an active membrane uptake in the resting state. Immunogold labelling of H+/K+-ATPase was seen on the tubulovesicular membranes. When stimulated with histamine, the cultured parietal cells undergo morphological transformation, resulting in great expansion of apical membrane vacuoles. Immunogold labelling of H+/K+-ATPase was present not only on the microvilli of expanded apical plasma membrane vacuoles but also in the electron-dense coated pits. The present findings provide a clue to vesicular membrane trafficking in cultured gastric parietal cells, and assure the utility of the new procedure for high-pressure freezing of primary culture cells.


Subject(s)
Freeze Substitution , Parietal Cells, Gastric/ultrastructure , Animals , Cells, Cultured , Cimetidine/pharmacology , H(+)-K(+)-Exchanging ATPase/metabolism , Histamine/pharmacology , Immunohistochemistry , Microscopy, Electron/methods , Parietal Cells, Gastric/drug effects , Rabbits
13.
Dig Dis Sci ; 47(5): 1001-7, 2002 May.
Article in English | MEDLINE | ID: mdl-12018894

ABSTRACT

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.


Subject(s)
Aminopyrine , Gastric Acid/metabolism , Gastric Mucosa/metabolism , Parietal Cells, Gastric/metabolism , Animals , Carbon Radioisotopes , In Vitro Techniques , Propionates , Proteins/analysis , Rabbits , Radiopharmaceuticals , Tritium
15.
Int J Pediatr Otorhinolaryngol ; 60(2): 123-30, 2001 Aug 20.
Article in English | MEDLINE | ID: mdl-11518589

ABSTRACT

OBJECTIVE: To evaluate efficacy and costs of a volunteer-based universal newborn hearing screening program. METHODS: The Lucile Packard Children's Hospital at Stanford newborn hearing screening program database was reviewed. Results and costs of the hearing screens were analyzed. RESULTS: Hearing screens were performed on 5771 newborns treated in the well-baby nursery and nine infants from this population were identified with hearing loss, seven of whom had no risks factors for hearing loss. Using volunteers to perform the first-line screen with the automated auditory brainstem response (AABR) technology, 91% of infants registered for screening were evaluated prior to discharge. An additional 4% of infants were screened as outpatients. If an infant failed the AABR on two occasions, he or she was rescreened with the AABR or transient evoked otoacoustic emissions by a licensed audiologist, often while the infant was still in the hospital. Using this algorithm, 5% of infants tested in the well-baby nursery needed additional follow-up as an outpatient. Cost analysis of this volunteer-based program reveals a per/baby screening cost of $27.41. CONCLUSIONS: A volunteer-based hearing screening program is a viable option for hearing screening in well-baby nurseries but does not result in significant cost savings during the first 2 years of the program.


Subject(s)
Hearing Disorders/diagnosis , Neonatal Screening/organization & administration , Audiometry/economics , Audiometry/methods , California , Costs and Cost Analysis , Evoked Potentials, Auditory, Brain Stem , Female , Follow-Up Studies , Hospital Volunteers , Hospitals, Pediatric , Humans , Infant, Newborn , Male , Program Development , Program Evaluation , Sensitivity and Specificity
16.
Am J Physiol Cell Physiol ; 281(2): C407-17, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11443040

ABSTRACT

Acid secretion by the gastric parietal cell is controlled through movement of vesicles containing the proton pump, the H(+)-K(+)-ATPase (HK). We have used latrunculin B (Lat B), which binds to monomeric actin, to investigate actin turnover in the stimulated parietal cell. In isolated gastric glands, relatively high concentrations of Lat B were required to inhibit acid accumulation (ED(50) approximately 70 microM). Cultured parietal cells stimulated in the presence of low Lat B (0.1--1 microM) have reduced lamellipodia formation and some aberrant punctate phalloidin-stained structures, but translocation of HK and vacuolar swelling appeared unaffected. High Lat B (10--50 microM) resulted in gross changes in actin organization (punctate phalloidin-stained structures throughout the cell and nucleus) and reduced translocation of HK and vacuolar swelling. Resting parietal cells treated with high Lat B showed minor effects on morphology and F-actin staining. If resting cells treated with high Lat B were washed immediately before stimulation, they exhibited a normal stimulated morphology. These data suggest distinct pools of parietal cell actin: a pool highly susceptible to Lat B primarily involved in motile function of cultured cells; and a Lat B-resistant pool, most likely microvillar filaments, that is essential for secretion. Furthermore, the stimulation process appears to accentuate the effects of Lat B, most likely through Lat B binding to monomer actin liberated by the turnover of the motile actin filament pool.


Subject(s)
Actins/metabolism , Parietal Cells, Gastric/metabolism , Acids/antagonists & inhibitors , Animals , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Cells, Cultured , Dose-Response Relationship, Drug , Fibroblasts/drug effects , Fibroblasts/metabolism , Gastric Mucosa/cytology , Gastric Mucosa/drug effects , Gastric Mucosa/metabolism , Homeostasis , In Vitro Techniques , Parietal Cells, Gastric/cytology , Parietal Cells, Gastric/drug effects , Rabbits , Stimulation, Chemical , Thiazoles/pharmacology , Thiazolidines
17.
J Physiol ; 532(Pt 2): 287-96, 2001 Apr 15.
Article in English | MEDLINE | ID: mdl-11306650

ABSTRACT

Gastric HCl secretion by the parietal cell involves the secretagogue-regulated re-cycling of the H+-K+-ATPase at the apical membrane. The trafficking of the H+-K+-ATPase and the remodelling of the apical membrane during this process are likely to involve the co-ordination of the function of vesicular trafficking machinery and the cytoskeleton. This review summarizes the progress made in the identification and characterization of components of the vesicular trafficking machinery that are associated with the H+-K+-ATPase and of components of the actin-based cytoskeleton that are associated with the apical membrane of the parietal cell. Since many of these proteins are also expressed at the apical pole of other epithelial cells, the parietal cell may represent a model system to characterize the protein- protein interactions that regulate apical membrane trafficking in many other epithelial cells.


Subject(s)
Actins/physiology , Cytoskeleton/physiology , H(+)-K(+)-Exchanging ATPase/metabolism , Parietal Cells, Gastric/physiology , Animals , Cell Membrane/physiology , Humans
18.
Am J Physiol Cell Physiol ; 279(3): C833-51, 2000 Sep.
Article in English | MEDLINE | ID: mdl-10942733

ABSTRACT

Clathrin from H-K-ATPase-rich membranes derived from the tubulovesicular compartment of rabbit and hog gastric acid secretory (parietal) cells was characterized biochemically, and the subcellular localization of membrane-associated clathrin in parietal cells was characterized by immunofluorescence, electron microscopy, and immunoelectron microscopy. Clathrin from H-K- ATPase-rich membranes was determined to be comprised of conventional clathrin heavy chain and a predominance of clathrin light chain A. Clathrin and adaptors could be induced to polymerize quantitatively in vitro, forming 120-nm-diameter basketlike structures. In digitonin-permeabilized resting parietal cells, the intracellular distribution of immunofluorescently labeled clathrin was suggestive of labeling of the tubulovesicular compartment. Clathrin was also unexpectedly localized to canalicular (apical) membranes, as were alpha-adaptin and dynamin, suggesting that this membrane domain of resting parietal cells is endocytotically active. At the ultrastructural level, clathrin was immunolocalized to canalicular and tubulovesicular membranes. H-K-ATPase was immunolocalized to the same membrane domains as clathrin but did not appear to be enriched at the specific subdomains that were enriched in clathrin. Finally, in immunofluorescently labeled primary cultures of parietal cells, in contrast to the H-K-ATPase, intracellular clathrin was found not to translocate to the apical membrane on secretagogue stimulation. Taken together, these biochemical and morphological data provide a framework for characterizing the role of clathrin in the regulation of membrane trafficking from tubulovesicles and at the canalicular membrane in parietal cells.


Subject(s)
Clathrin/metabolism , Gastric Acid/metabolism , Parietal Cells, Gastric/metabolism , Animals , Blotting, Western , Cells, Cultured , Chemical Fractionation , Chromatography , Clathrin/chemistry , Coated Pits, Cell-Membrane/metabolism , Durapatite , Freezing , Gastric Mucosa/metabolism , H(+)-K(+)-Exchanging ATPase/metabolism , Immunologic Techniques , Mass Spectrometry , Microsomes/metabolism , Polymers/metabolism , Rabbits , Subcellular Fractions/metabolism , Tissue Distribution
19.
J Med Food ; 3(1): 23-39, 2000.
Article in English | MEDLINE | ID: mdl-19281341

ABSTRACT

ABSTRACT The increased public awareness about herbal products has led to a growth of the botanicals market and attracted the interest of the pharmaceutical industry. The laws that regulate the sale of manufactured herbal products differ between regions and countries of the Western world. The European Union favors the classification of the remedies as medicinal products. However, differences in the interpretation of European law by the Member States have meant that herbal products have been assigned to various sale categories across the European market. The European Agency for the Evaluation of Medicinal Products is working to introduce changes to achieve harmonization within the market. Canada and Australia have embarked on similar reforms to improve product regulation without imposing undue restrictions on marketing. In these countries, herbal products have been assigned a status that respects their therapeutic role. Changes introduced in the United States of America in 1994 led to a deregulation of the market with herbal products being classified as dietary supplements and excluded from the stricter regulatory requirements applicable to drugs and foods. However, a United States Presidential Commission has advised that a study is needed regarding an alternative system for botanical products that are not used solely as dietary supplements but that cannot meet the requirements applicable for conventional over-the-counter drugs.

20.
J Med Food ; 3(1): 41-57, 2000.
Article in English | MEDLINE | ID: mdl-19281342

ABSTRACT

ABSTRACT A significant proportion of the general public has the misconception that herbal products are safe because they are of natural origin. Toxicity may arise from inherent properties of the herbal ingredients that result in adverse reactions, which may be serious, or from interactions with conventional drug substances. Toxicity may also be caused by misuse, abuse, and overuse of products and by adulteration of products or misidentification of plants. Regulatory authorities are undertaking to provide a reasonable assurance of efficacy and improved safety of herbal products through monitoring programs and control of herbs that are known to be toxic. Action is taken by the authorities to protect public health when herbal preparations are shown or suspected to cause harm. Case reports of toxicity due to herbal products and actions taken by regulatory authorities are summarized in this article. In the European Union, applicants for marketing authorizations may be required to provide scientific proof of safety and efficacy by reference to bibliographic data, where available. The relevance and credibility of published data needs to be assessed against recommended criteria in order to avoid unnecessary repetition of tests on animals or humans.

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