SEARCH · Search PubMed
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.
Vertical migration as an accumulation mechanism in the formation of red tide models is discussed with reference to extant mathematical models. Its relationship to other biological and physical factors such as population density changes, tidal rhythms, nutrient limitation and light intensity is evaluated in terms of its possible causal role in red tides.
Weather and tide variables were used to develop regression models with light trap counts of Aedes sollicitans (Walker) and Aedes taeniorhynchus (Wiedemann) from 1984 to 1995. Rains, tides, and temperatures, both during and preceding the sample period, all showed significant correlations with trap counts. These multiple regression models forecasted general population levels during 1996 and 1997, but not the size of the peaks. Therefore, weather alone can predict general trends but cannot be used to accurately predict population levels of Ae. sollicitans and Ae. taenio-rhynchus.
The parietal cell is capable of secreting high concentrations of hydrochloric acid into the lumen of the stomach. The apical membrane of this cell contains K+H+ ATPase, which is responsible for proton transport into the lumen. Potassium and chloride channels are also present. The basolateral membrane of the parietal cell possesses transporters that maintain intracellular homeostasis. Specifically, large amounts of bicarbonate that are generated by carbonic anhydrase must be removed from the cell to prevent alkalinization. Efflux of bicarbonate into the blood after acid secretion can be detected and is known as the alkaline tide. Determination of the alkaline tide has been used to measure acid secretion. In this review, we summarize the published data.
This report assesses the impact of the variability in environmental and vector factors on the transmission of Ross River virus (RRV) in Brisbane, Australia. Poisson time series regression analyses were conducted using monthly data on the counts of RRV cases, climate variables (Southern Oscillation Index and rainfall), high tides and mosquito density for the period of 1998-2001. The results indicate that increases in the high tide (relative risk (RR): 1.65; 95% confidence interval (CI): 1.20-2.26), rainfall (RR: 1.45; 95% CI: 1.21-1.73), mosquito density (RR: 1.17; 95% CI: 1.09-1.27), the density of Culex annulirostris (RR: 1.25; 95% CI: 1.13-1.37) and the density of Ochlerotatus vigilax (RR: 2.39; 95% CI: 2.30-2.48), each at a lag of 1 month, were statistically significantly associated with the rise of monthly RRV incidence. The results of the present study might facilitate the development of early warning systems for reducing the incidence of this wide-spread disease in Australia and other Pacific island nations.
We investigated growth rates, grazing rates, and prey selection of Polykrikos kofoidii when feeding on several species of red-tide and/or toxic dinoflagellates. Polykrikos kofoidii ingested all prey species used in this study, exhibiting positive growth on Lingulodinium polyedrum, Scrippsiella trochoidea, Ceratium furca, Gymnodinium catenatum, Gyrodinium impudicum, Prorocentrum micans, and the toxic dinoflagellate Amphidinium carterae, but not on P. minimum. Specific growth rates of P. kofoidii increased rapidly with increasing density of L. polyedrum, S. trochoidea, C. furca, and G. catenatum before saturating between 500-2,000 ng C ml(-1). Specific growth rates increased continuously when P. kofoidii was fed the other prey species. Maximum specific growth rates of P. kofoidii on G. catenatum (1.12 d(-1)), S. trochoidea (0.97 d(-1)), and L. polyedrum (0.83 d(-1)) were higher than those on C. furca (0.35 d(-1)), A. carterae (0.10 d(-1)), P. micans (0.06 d(-1)), G. impudicum (0.06 d(-1)), and P. minimum (-0.03 d(-1)). Threshold prey concentrations (where net growth = 0) were 54-288 ng C ml(-1). Maximum ingestion and clearance rates of P. kofoidii on these dinoflagellates were 5-24 ng C pseudocolony(-1) d(-1) and 1.0-5.9 microl pseudocolony(-1) h(-1), respectively. Polykrikos kofoidii strongly selected L. polyedrum over S. trochoidea in prey mixtures. Polykrikos kofoidii exhibited higher maximum growth, ingestion, and clearance rates than previously reported for the mixotrophic dinoflagellate Fragilidium cf. mexicanum or the heterotrophic dinoflagellates Protoperidinium cf. divergens and P. crassipes, when grown on the same prey species. Grazing coefficients calculated by combining field data on abundances of Polykrikos spp. and co-occurring red-tide dinoflagellate prey with laboratory data on ingestion rates obtained in the present study suggest that Polykrikos spp. sometimes have a considerable grazing impact on prey populations.
Two harvests of ocean-growing red tide, comprised mainly of Gonyaulax polyedra, were evaluated in limited trials of rat feeding. The protein of red tide (25 to 30 percent, dry basis) supported growth satisfactorily. The essential amino acid composition of the protein closely resembles that of casein, the major protein of milk. As a marine resource, plankton represents a challenge for research.
The growth characteristics of Heterosigma akashiwo virus clone 01 (HaV01) were examined by performing a one-step growth experiment. The virus had a latent period of 30 to 33 h and a burst size of 7.7 x 10(2) lysis-causing units in an infected cell. Transmission electron microscopy showed that the virus particles formed on the peripheries of viroplasms, as observed in a natural H. akashiwo cell. Inoculation of HaV01 into a mixed algal culture containing four phytoplankton species, H. akashiwo H93616, Chattonella antiqua (a member of the family Raphidophyceae), Heterocapsa triquetra (a member of the family Dinophyceae), and Ditylum brightwellii (a member of the family Bacillariophyceae), resulted in selective growth inhibition of H. akashiwo. Inoculation of HaV01 and H. akashiwo H93616 into a natural seawater sample produced similar results. However, a natural H. akashiwo red tide sample did not exhibit any conspicuous sensitivity to HaV01, presumably because of the great diversity of the host species with respect to virus infection. The growth characteristics of the lytic virus infecting the noxious harmful algal bloom-causing alga were considered, and the possibility of using this virus as a microbiological agent against H. akashiwo red tides is discussed.
A real-time reverse transcription-PCR method targeting the rbcL gene was developed for the detection and quantitation of the Florida red tide organism, Karenia brevis. The assay was sensitive to less than 1 cell per reaction, did not detect rbcL from 38 nontarget taxa, and accurately quantitated K. brevis organisms in red tide samples from around Florida. These studies have resulted in a sensitive and specific method for K. brevis detection in the marine environment.
The effect of the gastric alkaline tide on serum-ionized calcium levels was determined in human subjects. Gastric acid seretion was stimulated by a standard steak meal, human synthetic gastrin, and betazole hydrochloride. Ionized calcium levels fell to a similar extent after each stimulus. The mean decrease in calcium ion concentration in all experiments was 5.4% of the basal concentration. The fall in serum calcium ion concentration was highly correlated with the rise in serum pH. We speculate that increased formation of calcium bicarbonate complex in the serum as well as increased binding of ionized calcium by serum protein accounts for the surprisingly large effect of the alkaline tide on serumionized calcium levels.
The concept of an alkaline tide which compensates for gastric acid secretion suggests the possibility of indirect measurement of gastric acid secretion. This study was designed to determine whether postprandial changes in renal and respiratory function could be used to assess gastric secretion in healthy adults. Volunteers ate one of three standard (low, medium or high protein) breakfasts on separate days. A fall in urine acid output was observed during 2 h after the high protein meal, but not after the medium or low protein meal. Fasting subjects showed a similar fall in urine acid output over a 2-hour period. Pretreatment with ranitidine 150 mg b.i.d. had no effect on basal or postprandial urine acid output. We conclude that changes in urine acid output are not related to the gastric secretory response to food. In a separate study, treatment with omeprazole 20 mg daily had no effect on postprandial respiratory function (minute ventilation; mixed expired CO2; minute volume of CO2; respiratory exchange ratio; venous blood pH, pCO2 or bicarbonate; and end tidal CO2). Thus we were unable to detect a respiratory alkaline tide after a standard breakfast. These findings suggest that any respiratory or urinary compensation for gastric acid secretion is too small to be of physiological or clinical significance.
The increased metabolic rate during digestion is associated with changes in arterial acid-base parameters that are caused by gastric acid secretion (the 'alkaline tide'). Net transfer of HCl to the stomach lumen causes an increase in plasma HCO3- levels, but arterial pH does not change because of a ventilatory compensation that counters the metabolic alkalosis. It seems, therefore, that ventilation is controlled to preserve pH and not PCO2 during the postprandial period. To investigate this possibility, we determined arterial acid-base parameters and the metabolic response to digestion in the snake Boa constrictor, where gastric acid secretion was inhibited pharmacologically by oral administration of omeprazole. The increase in oxygen consumption of omeprazole-treated snakes after ingestion of 30% of their own body mass was quantitatively similar to the response in untreated snakes, although the peak of the metabolic response occurred later (36 h versus 24 h). Untreated control animals exhibited a large increase in arterial plasma HCO3- concentration of approximately 12 mmol l(-1), but arterial pH only increased by 0.12 pH units because of a simultaneous increase in arterial PCO2 by about 10 mmHg. Omeprazole virtually abolished the changes in arterial pH and plasma HCO3- concentration during digestion and there was no increase in arterial PCO2. The increased arterial PCO2 during digestion is not caused, therefore, by the increased metabolism during digestion or a lower ventilatory responsiveness to ventilatory stimuli during a presumably relaxed state in digestion. Furthermore, the constant arterial PCO2, in the absence of an alkaline tide, of omeprazole-treated snakes strongly suggests that pH rather than PCO2 normally affects chemoreceptor activity and ventilatory drive.
Brevetoxins are lipophilic polyether toxins produced by the red tide dinoflagellate Gymnodinium breve, and their neurotoxic effects on adult animals have been documented. In this study, we characterized adverse developmental effects of brevetoxin-1 (PbTx-1) using an exposure paradigm that parallels the maternal oocyte transfer of toxin. Medaka fish (Oryzias latipes) embryos were exposed to PbTx-1 via microinjection of toxin reconstituted in a triolein oil droplet. Embryos microinjected with doses of 0.1-8.0 ng/egg (ppm) of brevetoxin-1 exhibited pronounced muscular activity (hyperkinesis) after embryonic day 4. Upon hatching, morphologic abnormalities were commonly found in embryos at the following lowest adverse effect levels: 1.0-3.0 ppm, lateral curvature of the spinal column; 3.1-3.4 ppm, herniation of brain meninges through defects in the skull; and 3.4-4.0 ppm, malpositioned eye. Hatching abnormalities were also commonly observed at brevetoxin doses of 2.0 ppm and higher with head-first, as opposed to the normal tail-first, hatching, and doses > 4.1 ng/egg produced embryos that developed but failed to hatch. Given the similarity of developmental processes found between higher and lower vertebrates, teratogenic effects of brevetoxins have the potential to occur among different phylogenetic classes. The observation of developmental abnormalities after PbTx-1 exposure identifies a new spectrum of adverse effects that may be expected to occur following exposure to G. breve red tide events.
The 21st century promises to usher in an era of Internet based healthcare services--Tele-Healthcare. Such services augur well with the on-going paradigm shift in healthcare delivery patterns, i.e. patient centred services as opposed to provider centred services and wellness maintenance as opposed to illness management. This paper presents a Tele-Healthcare info-structure TIDE--an 'intelligent' wellness-oriented healthcare delivery environment. TIDE incorporates two WWW-based healthcare systems: (1) AIMS (Automated Health Monitoring System) for wellness maintenance and (2) IDEAS (Illness Diagnostic & Advisory System) for illness management. Our proposal comes from an attempt to rethink the sources of possible leverage in improving healthcare; vis-à-vis the provision of a continuum of personalised home-based healthcare services that emphasise the role of the individual in self health maintenance.
Pollution of heavy metal from industrial wastewater is a worldwide environmental problem. Biosorption is an effective technology for the treatment of low concentration industrial wastewater. The purpose of this study was to evaluate the heavy metal uptake capacities of the biomass of marine red tide Prorocentrum micans. All red tide biomass used in this study were obtained from cultivation in our lab. Batch experimental results showed that living and non-living biomass of P. micans killed by CH2O were similar setting property for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+. This study indicated that biomass of P. micans has a high capacities for above six heavy metal and the kinetics under the conditions studied were relatively fast. About 90% of the biosorption occurred within 10 min and an equilibrium was reached in 30 min. The Biosorption capacities for heavy metal ions were strongly dependent on pH of the solution, and higher capacities were obtained at pH around 5 and higher. Bonding and FIR of P. micans polysaccharide obtained by the hot water method for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+ was also studied. The study indicated that -OH and -CONH2 groups were active center of biosorption.
Zooplankton was surveyed in a tropical lagoon system of the northern coast of the Yucatan Peninsula in high tide, December (1998) and low tide, March 1999 (northerlies season). Zooplankton biomass was measured, zooplankters were counted, and copepods were identified and quantified. Despite the fact that both months were influenced by winds from the North, they showed a different salinity gradient which developed a particular structure of the zooplankton community. Biomass tended to be accumulated in certain areas apparently because of the high residence time of water in Chelem, the forcing effect of the northerlies, and of the tidal current. Biomass values suggest a relatively high secondary production when compared with other systems of the Yucatan Peninsula. The distribution of the copepods Acartia lilljeborgii and A. tonsa is related to saline conditions and tidal flow. The overall faunistic and hydrologic data suggest that even during a single climatic season, the zooplankton community shows strong changes due to mesoscale hydrological processes.
Five typical stations in the Changjiang River estuary and adjacent waters of the East China Sea, were chosen as the sites to study phytoplankton growth and microzooplankton ingestion by on-deck-incubation dilution experiment from 25th April to 25th May 2002. The results showed that microzooplankton ingestion was a key process for controlling red tide event. Strombidium sulcatum, Noctiluca scintillans and Mesodinium robudium were dominant microzooplankton species. In this study, the ingestion rate of microzooplankton ranged from 0.28 to 1.13 d-1; ingestion pressure on percentage of phytoplankton standing crop ranged from 35.14% to 811.69%; ingestion pressure on percentage of potential production ranged from 74.04% to 203.25%; and ingestion rate of phytoplankton carbon ranged from 9.58 to 97.91 C.L-1.d-1. The microzooplankton grazing rate, ingestion pressure on percentage of phytoplankton standing crop, and ingestion rate of phytoplankton carbon were higher near coastal area, but lower at open sea, and the microzooplankton ingestion pressure on percentage of phytoplankton potential production was no the contrary. Compared with the similar studies around the world, the ingestion pressure of microzooplankton in the East China Sea was at a higher level. The primary deduction was that Strombidium was the key microzooplankton species on controlling Prorocentrum dentatum, the most important red tide species in the East China Sea.
The spectral characteristics of the coastal waters in East China Sea was studied using in situ measurements, and the multiband algorithms of remote sensing for bloom waters was discussed and developed. Examples of red tide detection using the algorithms in the East China Sea were presented. The results showed that the algorithms could provide information about the location and the area coverage of the red tide events.
The ecotoxicological and biochemical study with Heterosigma akashiwo, Alexandrium tamarense and Skeletonema costatum showed that the test three species of red-tide microalgae had different sensitivities to UV-B radiation enhancement, and the order from high to low was Heterosigma akashiwo, Alexandrium tamarense and Skeletonema costatum. The DNA damage of algal cells increased with UV-B radiation enhancement, being more notable in Heterosigma akashiwo than in Alexandrium tamarense and Skeletonema costatum, and in Alexandrium tamarense than in Skeletonema costatum. The DNA damage of Heterosigma akashiwo and Alexandrium tamarense could be significantly repaired (P < 0.05) after 6 days of UV-B radiation removal, and that of Skeletonema costatum could be significantly repaired (P < 0.05) after 3 days, which illustrated that the DNA damage of three red-tide microalgae species could not indicate the damaged degree of marine microalgae resulted from UV-B radiation enhancement.