Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2005

Initial evaluation of the effects of aerosolized Florida red tide toxins (brevetoxins) in persons with asthma.

Florida red tides annually occur in the Gulf of Mexico, resulting from blooms of the marine dinoflagellate Karenia brevis. K. brevis produces highly potent natural polyether toxins, known as brevetoxins, that activate voltage-sensitive sodium channels. In experimental animals, brevetoxins cause significant bronchoconstriction. A study of persons who visited the beach recreationally found a significant increase in self-reported respiratory symptoms after exposure to aerosolized Florida red tides. Anecdotal reports indicate that persons with underlying respiratory diseases may be particularly susceptible to adverse health effects from these aerosolized toxins. Fifty-nine persons with physician-diagnosed asthma were evaluated for 1 hr before and after going to the beach on days with and without Florida red tide. Study participants were evaluated with a brief symptom questionnaire, nose and throat swabs, and spirometry approved by the National Institute for Occupational Safety and Health. Environmental monitoring, water and air sampling (i.e., K. brevis, brevetoxins, and particulate size distribution), and personal monitoring (for toxins) were performed. Brevetoxin concentrations were measured by liquid chromatography mass spectrometry, high-performance liquid chromatography, and a newly developed brevetoxin enzyme-linked immunosorbent assay. Participants were significantly more likely to report respiratory symptoms after Florida red tide exposure. Participants demonstrated small but statistically significant decreases in forced expiratory volume in 1 sec, forced expiratory flow between 25 and 75%, and peak expiratory flow after exposure, particularly those regularly using asthma medications. Similar evaluation during nonexposure periods did not significantly differ. This is the first study to show objectively measurable adverse health effects from exposure to aerosolized Florida red tide toxins in persons with asthma. Future studies will examine the possible chronic effects of these toxins among persons with asthma and other chronic respiratory impairment.

Adolescent↗
PubMed2005

Occupational exposure to aerosolized brevetoxins during Florida red tide events: effects on a healthy worker population.

Karenia brevis (formerly Gymnodinium breve) is a marine dinoflagellate responsible for red tides that form in the Gulf of Mexico. K. brevis produces brevetoxins, the potent toxins that cause neurotoxic shellfish poisoning. There is also limited information describing human health effects from environmental exposures to brevetoxins. Our objective was to examine the impact of inhaling aerosolized brevetoxins during red tide events on self-reported symptoms and pulmonary function. We recruited a group of 28 healthy lifeguards who are occupationally exposed to red tide toxins during their daily work-related activities. They performed spirometry tests and reported symptoms before and after their 8-hr shifts during a time when there was no red tide (unexposed period) and again when there was a red tide (exposed period). We also examined how mild exercise affected the reported symptoms and spirometry tests during unexposed and exposed periods with a subgroup of the same lifeguards. Environmental sampling (K. brevis cell concentrations in seawater and brevetoxin concentrations in seawater and air) was used to confirm unexposed/exposed status. Compared with unexposed periods, the group of lifeguards reported more upper respiratory symptoms during the exposed periods. We did not observe any impact of exposure to aerosolized brevetoxins, with or without mild exercise, on pulmonary function.

Adolescent↗
PubMed2006

[Study of red tide spectral characteristics and its mechanism].

In situ spectral data of different red tide, whose dominant species are leptocylindrus danicus, chattonella marina, skeletonema costatum, and mesodinium rubrum, were acquired by above water method utilizing spectrometer manufactured by FieldSpec Dual VNIR (USA). It is emphasized that the characteristic reflectance peak lying between 687 and 728 nm can be used to distinguish between red tide and normal sea water. Also the spectral discrepancy between different dominant species of red tide is pointed out, which could be utilized to identify certain red tide species by remote sensing technique. Mechanisms of phytoplankton red tide spectra peaks and vales are given. Spectral characteristics of mesodinium rubrum, a kind of protozoan, may be related to its symbiotic alga in its body and phytoplankton pigment crumb. So, research on ingestion preference, symbiotic property with algae, and fluorescence emission character of such symbiotic algae under normal temperature may be helpful for the deep understanding of mechanism of mesodinium rubrum spectra.

Ciliophora↗
PubMed1986

Red tide (Ptychodiscus brevis) toxin aerosols: a review.

Advances in knowledge concerning red tide toxin aerosols (airborne) of the Florida red tide organism, Ptychodiscus brevis, have not kept pace with information about waterborne toxins. This review provides a summary of current knowledge regarding the characterization, effect and production of red tide toxin aerosols. Insight into the chemical characterization and toxic effects of aerosolized toxins is provided from investigations of toxins extracted from natural blooms, as well as from laboratory cultures, of P. brevis. This information is used in conjunction with the few studies that have been performed on toxin aerosols to consider toxic effects. The production of aerosolized toxins is considered through studies of jet drop aerosol formation from bursting bubbles. Existing information suggests that aerosolized red tide toxins may be the same chemicals as those extracted from laboratory cultures, with one of the toxins having a greater respiratory effect than others.

Aerosols↗
PubMed1996

A review of radionuclides in tide-washed pastures on the Irish Sea coast in England and Wales and their transfer to food products.

Close to the Sellafield Reprocessing Plant activity concentrations of many radionuclides including the long-lived 137Cs and actinides on tide-washed pastures bordering the Irish Sea are high compared with other terrestrial ecosystems in the United Kingdom. Despite the comparatively high deposition of radionuclides, contamination of agricultural products from tide-washed pastures is lower than would be predicted from studies in terrestrial ecosystems. This is because the main source of contamination in tide-washed pasture, radionuclides associated with sedimentary particles, has low availability for uptake by plant roots and in the gut of ruminants. Generalised Derived Limits (GDLs), published by the National Radiological Protection Board (NRPB) are estimates of environmental radioactivity concentrations which would potentially be radiologically significant. These provide a benchmark against which environmental measurements can be assessed. In the past, several comparisons of radioactivity concentrations in tide-washed pastures with GDLs have been made, but only some of these comparisons are valid since current approaches used to assess doses are not always strictly appropriate to these ecosystems. Directly applicable GDLs are needed, and are currently being developed by the NRPB.

Journal Article↗
PubMed2001

Standing stock and production rate of phytoplankton and a red tide outbreak in a heavily eutrophic embayment, Dokai Bay, Japan.

The seasonal variation of phytoplankton biomass and primary productivity in a heavily eutrophic embayment, Dokai Bay, Japan, was determined. Dokai Bay was characterized by high phytoplankton biomass and productivity during summer and low phytoplankton biomass and productivity during other seasons. The results suggested that phytoplankton growth was limited by only irradiance and water temperature under the high nutrient concentrations available for phytoplankton growth in the entire year. Moreover, in spite of sufficient nutrient for phytoplankton growth in the entire year, a red tide occurred only in the summer period in this bay. Our results suggested that a red tide occurred by the high phytoplankton growth rate in the summer season, but in other periods surface phytoplankton was flushed out of the bay before forming the red tide, because phytoplankton growth rate was low and could not form the red tide due to low irradiance and low water temperature.

Animals↗
PubMed2005

Child dermal sediment loads following play in a tide flat.

Dermal contact with sediment is sometimes identified as a pathway of concern in risk assessments. Dermal exposure to sediment is poorly characterized and exposure assessors may rely on default soil adherence values. The purpose of this study was to obtain sediment adherence data for a genuine exposure scenario, child play in a tide flat. This study reports direct measurements of sediment loadings on five body parts (face, forearms, hands, lower legs and feet) after play in a tide flat. Each of nine subjects participated in two timed sessions and pre- and post-activity sediment loading data were collected. Geometric mean (geometric standard deviation) dermal loadings (mg/cm(2)) on the face, forearm, hands, lower legs and feet for the combined sessions were 0.04 (2.9), 0.17 (3.1), 0.49 (8.2), 0.70 (3.6) and 21 (1.9), respectively. Participants' parents completed questionnaires regarding their child's typical activity patterns during tide flat play, exposure frequency and duration, clothing choices, bathing practices and clothes laundering. Data presented in this paper supplement very limited prior adherence data for sediment contact scenarios. Results will be useful to risk assessors considering exposure scenarios involving child activities at a coastal shoreline or tide flat.

Administration, Cutaneous↗
PubMed1990

Changes in bacterial populations during red tides caused by Mesodinium rubrum and Gymnodinium catenatum in North West Coast of Spain.

Heterotrophic bacterial communities associated with four red tides caused by Mesodinium rubrum and Gymnodinium catenatum in two Galician Rias (North West Spain) were examined. Three of these were produced by the Mesodinium rubrum and the causative organism of a toxic bloom was Gymnodinium catenatum. In early stages of all the blooms, the diversity decreased but the total marine bacterial counts increased by one or two logs. Vibrio numbers were also incremented by two logs in two blooms of M. rubrum, while in the other bloom of this organism and in the red tide caused by G. catenatum a decrease in number of these bacteria was observed. A total of 116 bacterial strains were identified at the genus level and grouped into 12 phena. During the decomposition processes of two blooms of M. rubrum a zooplanktonic-type bacterial succession was observed (Vibrio, pseudomonads and Moraxella-Acinetobacter). On the other hand, during decomposition of the other red tide of M. rubrum and the bloom of G. catenatum, a typical phytoplanktonic-type succession occurred, as Pseudomonas and Moraxella groups became dominant for all the process. These results support the conflicting taxonomical position of M. rubrum. After the blooms, the changes in the community point towards the restablishment of the normal bacterial flora of the estuary (increase in diversity and decreases of bacterial numbers). Only the Vibrio strains, isolated from the non-toxic first and second red tides, displayed cytotoxic activities. A relationship among bacterial cytotoxicity and toxic effects of blooms cannot therefore be established.

Animals↗
PubMed1990

Vibrios associated with red tides caused by Mesodinium rubrum.

Vibrios were isolated from red tides caused by Mesodinium rubrum and also throughout the year in the Ria de Pontevedra, Spain. The isolates were grouped into 14 phena by numerical toxonomy. Strains associated with red tides were restricted to four phena: phena I and II were Vibrio alginolyticus, and phena III and IV were Vibrio tubiashii and Vibrio anguillarum, respectively. V. anguillarum-like strains (phena V through XI) predominated throughout the year outside the red tide areas. Cytotoxicity assays conducted in different poikilothermic and homoiothermic cell lines showed that cytotoxin production was not necessarily associated with the species selected during the red tides.

Animals↗
PubMed2005

Overview of aerosolized Florida red tide toxins: exposures and effects.

Florida red tide is caused by Karenia brevis, a dinoflagellate that periodically blooms, releasing its potent neurotoxin, brevetoxin, into the surrounding waters and air along the coast of the Gulf of Mexico. Exposure to Florida red tide toxins has been associated with adverse human health effects and massive fish and marine mammal deaths. The articles in this mini-monograph describe the ongoing interdisciplinary and interagency research program that characterizes the exposures and health effects of aerosolized Florida red tide toxins (brevetoxins). The interdisciplinary research program uses animal models and laboratory studies to develop hypotheses and apply these findings to in situ human exposures. Our ultimate goal is to develop appropriate prevention measures and medical interventions to mitigate or prevent adverse health effects from exposure to complex mixtures of aerosolized red tide toxins.

Aerosols↗
PubMed2000

Comparison of arterial blood gases and acid-base balance in young and aged beagle dogs, with regard to postprandial alkaline tide.

Arterial blood pH and blood gas tensions were measured before and after feeding in seven young (1-year-old) and 6 aged (10 to 12 year-old) conscious beagle dogs with a portable "i-STAT" blood gas analyzer to obtain the fundamental physiological data on the laboratory dogs. Before feeding, arterial blood pH, HCO3- and base excess (BE) were 7.395 +/- 0.022, 20 +/- 1.0 mmol/L and -4 +/- 1.1 mmol/L in young dogs, and 7.408 +/- 0.031, 23 +/- 1.5 mmol/L and -2 +/- 1.8 mmol/L in aged ones. After feeding, the above values changed to 7.449 +/- 0.021, 25 +/- 1.1 and 1 +/- 1.3 in young dogs, and 7.456 +/- 0.022, 28 +/- 1.7 and 4 +/- 1.9 in aged ones. After feeding, each of the values for pH, HCO3- and BE was increased in comparison with those before feeding in both young and aged dogs, and alkalinization of blood, the alkaline tide, was observed in all healthy dogs. The values for PCO2 also rose from 33.6 +/- 1.91 to 36.7 +/- 1.95 (mmHg) in young dogs, and 36.4 +/- 2.97 to 40.3 +/- 3.06 (mmHg) in aged ones, and in 3 of 6 aged dogs slight hypoxia (PO2 < 80 mmHg) was noted. These changes in PCO2 and PO2 were considered to be due to compensatory hypoventilation for the alkalinization of blood. To confirm the cause of the alkaline tide phenomenon, we investigated the association of the alkaline tide with gastric acid secretion by cimetidine, an H2-blocker; and found that it was effective to inhibit postprandial alkaline tide in dogs. After feeding, ionized Ca concentration (iCa) was decreased inversely with an arterial blood pH increase in both young and aged dogs. The mean values of iCa in aged dogs after feeding was lower than those in young dogs. In the present experiments, it was demonstrated that in beagle dogs the acid-base balance and blood gas values were largely affected by feeding, especially in aged dogs. In case blood gases would be evaluated in toxicity studies, we should consider the influence of feeding and aging.

Acid-Base Equilibrium↗
PubMed2003

[Nutrient distribution and its relationship with occurrence of red tide in coastal area of East China Sea].

Nutrient (NO3(-)-N, PO4(3-)-P, Sio3(2-)-Si, NH4(+)-N, etc.) concentrations in coastal area of East China Sea were measured during April 25 to May 2, 2002, and the relationship between the spatial distribution of the nutrients and the red tide occurrence in the studied area was analyzed. The results showed that compared to the 1st class seawater quality of the national standard, the concentrations of dissolved inorganic nitrogen (DIN) and PO4(-)-P were 46% and 60% higher, respectively, showing that the studied area, especially the Changjiang River estuary and the Hangzhou Bay, was at a disadvantage of eutrophication. Furthermore, the nutrient concentrations inshore were much higher than those offshore, and the isolines nearly paralleled with the coastline, meaning that the nutrient distributions were mainly influenced by terrestrial discharges. It also showed that the relatively high concentrations of nutrients, especially DIN and PO4(3-)-P, might result in the red-tide occurrence. However, the red tide did not occur in the area with the highest concentrations of the nutrients, further demonstrating that the eutrophication was not the unique environmental factor inducing red-tide occurrence.

China↗
PubMed2003

[Temporal dynamics of phytoplankton and nutrients during red tides].

The relationships between temporal dynamics of phytoplankton density and nutrients (NO3-, NH4+, PO4(3-), SiO3(2-), Fe) contents in the water body at Aotou waters of Daya Bay during red tide were comprehensively analysed based on the fixed position investigation of red tide in the summer of 2000 and the several years investigation data by using grey linear regression model. The relationships between phytoplankton cell density and chlorophyll a content were also analysed. The results showed that the predicted values were well consistent with the measurement values, and their correlation coefficients were between 0.51-0.83. Red tide might break out if chlorophyll a contents in water body were larger than 5.8 micrograms.dm-3. The study could provide a simple effective method to forecast red tide by sampling water samples to analyse chlorophyll a concentration, or using SeaWiFS data, and then, to calculating phytoplankton density. In addition, the primary productivity of the water areas was controlled by phosphorus.

Chlorophyll↗
PubMed2003

[Removal of different species of red tide organisms with an effective clay-complex system].

An effective clay-complex system was composed on the base of clay by added other two components A and B. Different red tide species, such as Scrippsiella trochoidea, Amphidinium carterae and Heterosigma akashiwo, were coagulated by this clay-complex system, and the optimum conditions for removal red tide organisms were obtained by means of orthogonal test. The results showed that clay was the most important factors in this complex system to coagulate these three organisms. The removal efficiency on three species was in order of Scrippsiella trochoidea > Amphidinium carterae > Heterosigma akashiwo. At the same time, a preliminary study of mortality rate on Penaeus japonicus (length between 1.0 to 1.5 cm) was conducted with this system, and the result of toxic test revealed that the mortality of aquaculture shrimp in control group (nothing added) reached to 80% after 96 h, however, while that of other three groups which added clay and other two components A and B, was below 40%. Thus, it implied that the addition of clay would be harmless to Penaeus japonicas. Furthermore, suitable concentration of components A and B was not harmful for the aquaculture shrimp, but increased the removal efficiency of red tide organisms. The preliminary results showed that this clay-complex system would be available in the removal of red tide organisms in filed.

Aluminum Silicates↗
PubMed2006

[Mechanisms of removing red tide organisms by organo-clays].

We tested the influence of the preparation conditions of the quaternary ammonium compounds (QACs) modified clays on their capacities to remove red tide organisms, then discussed the mechanisms of the organo-clays removing red tide organisms. Hexadecyltrimethylammonium (HDTMA) improved the capacity of clays to flocculate red tide algae, and the HDTMA in metastable state enhanced the toxicity of the clay complexes to algae. The capacities of the organo-clays correlated with the toxicity and the adsorbed amount of the QACs used in clays modification, but as the incubation time was prolonged the stability of the organo-clays was improved and the algal removal efficiencies of the clay complexes decreased. When the adsorbed HDTMA was arranged in different clays in which the spatial resistance was different, there was more HDTMA in metastable state in the three-layer montmorillonite. Because of the homo-ion effect the bivalent or trivalent metal ions induced more HDTMA in metastable state and the corresponding organo-clays had high capacities to remove red tide organisms. When the reaction temperature was 60 degrees C the adsorbed HDTMA was easily arranged on cation exchange sites, if the temperature rose or fell the metastable HDTMA would increase so that the capacity of the clays was improved.

Adsorption↗
PubMed1980

Preservation of urinary postprandial alkaline tide despite inhibition of gastric acid secretion.

Ingestion of food leads to a rise in urinary pH. This phenomenon is commonly known as "postprandial alkaline tide" and is generally attributed to acid secretion in the stomach. To examine this hypothesis, we studied the changes of urinary pH, H+ concentration, PCO2, and bicarbonate in nine healthy volunteers with and without histamine H2 receptor blockade, using cimetidine and placebo medication. Postprandial alkaline tide persisted and was even exaggerated during treatment with cimetidine. Preservation of postprandial urinary alkaline tide, despite the expected inhibition of gastric acid secretion by cimetidine, tends to exclude a causal relation between alkaline tide and gastric acid secretion.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Red tides in México: a review].

With the purpose to make a review on the red tides occurence at mexican coasts, previous studies were analyzed. Dinoflagellates seem to be the main cause of toxic events mainly Gonyaulax polygramma, Gymnodinium catenatum, Pyrodinium bahamense var. compressum and Ptychodiscus brevis. There are other species which cause red tides but are not toxic. They are: Mesodinium rubrum, Gonyaulax triacantha, Noctiluca scintillans, Prorocentrum dentatum, Gymnodinium splendens, G. sanguineum, Ceratium tripos var. ponticum, C. furca, Scrippsiella trocoidea and Oscillatoria erythraea. The first of these is the most common cilliate of the Pacific coastlines and the last one is the most common cyanophyceae during the strong events of "El Niño". The magnitude is quite variable, from small stains of a hundred square meters to several square kilometers and its density ranges from 0.5 to 36 million cells/l. Their residence time goes from 1 or 2 days to as long as 5 months. The great densities are due to Prorocentrum dentatum and P. minimum, the latter is only observed in estuarine ponds for shrimp cultivation, they have not been related to poisoning episodes. New areas of the red tide occurrence have been recorded during the last decades, such as Acapulco Bay, Huatulco, Salinacruz and Puerto Madero. These localities and also Mazatlán, are the only regions in which paralytic shellfish poisoning (PSP) have registered fatal cases and in the Gulf of Mexico a great mortality of fishes has been noted due to ictiotoxin produced by Ptychodiscus brevis. On the other hand, at Yucatan and west coast of the Peninsula of California red tide events are little known.

Animals↗
PubMed1991

Free radical production by the red tide alga, Chattonella antiqua.

The red tide alga, Chattonella antiqua, was found to show a strong chemiluminescence, using luminol as the reagent, when exposed to ultraviolet irradiation. This luminescence was completely inhibited by ascorbate or catalase, suggesting that hydrogen peroxide was generated by the plankton. Red tide cells exposed to fish gill mucus from young yellowtail resulted in the release of a large number of mucocysts and a weak luminosity, and showed a strong reduction of cytochrome c in the medium. Therefore, the discharge of mucocysts from the red tide, induced by the presence of gill mucus, may be accompanied by the release of active oxygen species. The active oxygen may be involved in depolymerization of mucus glycoproteins from the gill lamellae.

Animals↗