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PubMedDate not supplied

Chemometric studies in the Lagoon of Venice, Italy. Annual evolution of sulphur species and relationship to biogeochemical cycles in lagoon water.

During the period March 1997-March 1998 dimethyl sulphide (DMS), dimethylsulphoniopropionate (DMSP) and carbon disulphide (CS2) were determined weekly in the water of the Lagoon of Venice, Italy (at three stations located in the Giudecca Canal, the San Secondo Canal and the Rio di San Nicolò). At the same time, the following hydrological and biological variables were also measured: tide height, temperature, transmittance, fluorescence, pH, salinity, chlorinity, sulphate, ammonia, nitrite, nitrate, phosphate, silicate, chlorophyll a, phaeopigments, phytoplankton (abundance and biomass). Principal component analysis (PCA), applied as a dimension reduction tool, made it possible to summarize multivariate information in a small number of components, which highlighted the relationships between the temporal evolutions of the sulphur compounds with hydrological and biological variables in the seasonal biogeochemical cycle of the lagoon. In particular the overall temporal cycle, which begins with the development of biological activity in late winter and spring, followed by the predominance of degradation processes during the late summer and the remineralization of nutrients in autumn, is clearly described in the plane of the first two principal components, together with the interrelationships between all the relevant variables.

Environmental Monitoring↗
PubMed2007

Polishing a diamond in the rough: "Cu--H" catalysis with silanes.

The value of a novel chemical transformation is often underappreciated at the time of its discovery. The reasons are doubtlessly manifold, but the "chemical zeitgeist" subtly determines how the new reaction will be received by the chemical community. The enantioselective reduction of carbonyls by copper-catalyzed hydrosilylation was certainly outshone by other asymmetric hydrogenation techniques. A seminal report at an early stage indicated the considerable potential of this catalytic process, yet it was disregarded for more than a decade. A refined mechanistic picture in connection with a plethora of new chiral ligands then led to copper-catalyzed 1,2- as well as 1,4-reductions of carbonyl compounds with excellent levels of enantioselection at high substrate-to-catalyst ratios and even more remarkable substrate-to-ligand ratios. The tide is turning for inexpensive copper catalysts in asymmetric hydride transfer reactions!

Journal Article↗
PubMed1979

Percutaneous transhepatic occlusion for bleeding oesophageal varices.

Using the technique described by Lunderquist et al. (1977), transhepatic injection of oesophageal varices has been performed under local anaesthesia in 9 patients with portal hypertension (11 procedures). On 2 occasions it was not possible to enter the left gastric vein. Bleeding resumed within 2 days of radiologically satisfactory occlusion in 2 patients and at 1, 3, 4 and 10 months after 4 procedures in 3 patients. Other complications included portal vein thrombosis, gross ascites and right pleural effusion. There were 2 hospital deaths, both in alcoholic patients with poor hepatic function. In spite of the apparently high morbidity we consider that there is a place for this technique in tiding over patients who are bleeding from oesophageal varices and are medically unsuitable for any surgical procedure.

Adult↗
PubMed1981

252Californium plasma desorption mass spectrometry.

The mass spectrometry of involatile molecules presents problems not encountered when the molecule can be volatilized and subsequently ionized in the gas phase. The production of ions from a condensed phase is sensitively dependent on the properties of the matrix. The presence of impurities in the sample can totally quench molecular ion formation even though the sample contains a high percentage of the molecule of interest. One of the methods used for the mass spectrometry of involatile molecules is 252Californium plasma desorption mass spectrometry. The basic principles of this method will be presented with examples of its application that include the identification of involatile marine toxins (including the red tide toxins). We shall also introduce a new variation in mass spectrometry, a study of time-dependent effects, a technique that can be used to follow dynamic changes as a result of chemical reactions occurring in the sample at room temperature. This is possible in 252Californium plasma desorption mass spectrometry because the sample is conserved during the analysis.

Californium↗
PubMed2006

A cadaveric investigation into the links between macroscopic and microscopic osteoarthritic changes at the hip.

Our objective was to investigate the frequency and distribution of osteoarthritic changes at the hip, including the relationship between osteoarthritic lesions on the femoral head surface and histological changes in articular cartilage, in 12 cadavers. Twelve embalmed cadavers (five males and seven females) were dissected, and the femoral head was removed from both sides (24 femoral heads). Any gross osteoarthritic changes were noted and graded (on a scale of 1-3). A circular disc was then removed from the equator of the femoral head and divided into nine regions. Out of 192 segments, 54 underwent sectioning and staining with haematoxylin and eosin to assess histological changes in cartilage. Osteoarthritis of the hip was present in all cadavers, with all males having bilateral OA and 50% having grade 2 or higher lesions (50% were grade 1), and four of the seven female specimens having bilateral OA and only 7% with grade 2 lesions (with 71% grade 1 and 21% normal). Chondrocyte clustering was most commonly observed in the deep layer of cartilage followed by the intermediate and superficial layers respectively, as the grade of the macroscopic lesion increased. Cartilage injury at the histological level precedes any visible denudation of the femoral head articular cartilage. This study supports the hypothesis that early osteoarthritic changes occur in the deep layer of cartilage near the tide mark and progress superficially concomitant with an overall increase in the osteoarthritic lesion size on the femoral head surface.

Aged↗
PubMed1997

Analysis of brevetoxins by micellar electrokinetic capillary chromatography and laser-induced fluorescence detection.

Micellar electrokinetic capillary chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used to measure four red tide brevetoxins at sub-attomole levels. The separation of four brevetoxins by MEKC was achieved with a sodium borate/sodium dodecyl sulfate buffer at pH 9.3 Brevetoxins with a terminal alcohol group were derivatized with an acyl azide coumarin to form stable, highly fluorescent products. Brevetoxins with a terminal aldehyde group were reduced to the alcohol with sodium borohydride prior to derivatization with the coumarin. Three derivatized brevetoxins (PbTx-3, PbTx- 5, and PbTx-9) were separated by MEKC and detected using He/Cd laser excitation at 354 nm and fluorescence emission at 410 nm. A fourth brevetoxin (PbTx-2) was converted to PbTx-3 prior to derivatization and was then determined by subtraction. Instrumental detection limits for all four toxins were approximately 0.10 fg or about 10(6)-fold more sensitive than existing liquid chromatographic methods. Brevetoxins were isolated from cell cultures and fish tissue using an alumina column/gel-permeation chromatography procedure. Method detection limits for the brevetoxins in fish tissue were approximately 4 pg/g. These method detection limits are at least 100-fold better than previous chromatographic and/or electrophoretic methods. The MEKC-LIF method reported here allows measurement of brevetoxins at the trace levels considered critical for understanding toxin metabolism and mode of action.

Animals↗
PubMed2003

Peroxisome proliferation as a biomarker in environmental pollution assessment.

Peroxisome proliferators comprise a heterogeneous group of compounds known for their ability to cause massive proliferation of peroxisomes and liver carcinogenesis in rodents. In recent years it has become evident that other animals may be threatened by peroxisome proliferators, in particular aquatic organisms living in coastal and estuarine areas. These animals are exposed to a variety of pollutants of industrial, agricultural and urban origin which are potential peroxisome proliferators. Both laboratory and field studies have shown that phthalate ester plasticizers, PAHs and oil derivatives, PCBs, certain pesticides, bleached kraft pulp and paper mill effluents, alkylphenols and estrogens provoke peroxisome proliferation in different fish or bivalve mollusc species. The response appears to be mediated by peroxisome-proliferator activated receptors, members of the nuclear receptor family, recently cloned in fish. Based on these results it is proposed that peroxisome proliferation could be used as a biomarker of exposure to a variety of pollutants in environmental pollution assessment. This is illustrated by a case study in which mussels, used worldwide as sentinels of environmental pollution, were transplanted from reference to contaminated areas and vice versa. In mussels native to an area polluted with PAHs and PCBs, peroxisomal acyl-CoA oxidase (AOX) activity and peroxisomal volume density were 2-3 fold and 5-fold higher, respectively, compared to the reference site. When animals were transplanted to the polluted station, with increased concentration of organic xenobiotics, a concomitant significant increase of AOX was recorded. Conversely, in animals transplanted to the cleaner station, AOX activity and peroxisomal volume density decreased significantly. These results indicate that peroxisome proliferation is a rapid (i.e., two days) and reversible response to pollution in mussels. Before peroxisome proliferation can be implemented as a biomarker in biomonitoring programs, a well-defined protocol should be established and validated in intercalibration and quality assurance programmes. Furthermore, the influence of biotic and abiotic factors, some of which are known to affect peroxisome proliferation (season, tide level, interpopulation and interindividual variability), should be taken into consideration. The possible hepatocarcinogenic effects as well as the potential adverse effects on reproduction, development, and growth of peroxisome proliferators are unknown in aquatic organisms, thus providing a challenge for future investigations.

Acyl-CoA Oxidase↗
PubMed2006

Induction of hatching by chemical signals secreted by the ovigerous female of an estuarine crab Sesarma haematocheir.

Hatching of embryos in the estuarine crab Sesarma haematocheir is highly synchronized with nocturnal high tide and completes within 1 hr among all embryos incubated by the female. This highly synchronized hatching is induced by a "Hatching-Program Inducing Factor (HPIF)" released from the female. To further define the cues involved in synchronized hatching, experiments were designed to characterize this factor and to determine possible sites of release and temporal release patterns using strategies involving isolation of egg masses, perfusion, and ablation experiments on fully developed embryos that had not yet entered the hatching program. Embryo transplantations indicate that not only HPIF may be released from the branchial chamber, but that it is extraordinarily unstable, and loses activity within 15 min, which frustrates further attempts at characterization. Nevertheless, with regard to temporal release patterns, it was established that HPIF activity was detected during short periods over three consecutive nights prior to release of larvae. This activity did not explain the gated response of embryo release in this crab, which might correspond with circatidal larval release events in the field.

Animals↗
PubMed1979

Short-term effects on Artemia salina of aponin and Gomphosphaeria aponina in unialgal cultures and in mixed cultures with gymnodinium breve.

Previous investigations showed that the natural marine substance aponin, produced by the blue-gree alga Gomphosphaeria sponina, was cytolytic towards Florida's red tide organism, Gymnodinium breve. As part of a study of the aponin-alga biological interactions, the effects of unialgal (G. aponina) and mixed cultures (G. aponina + G. breve) on the viability of artemia salina were investigated. Two contrasting effects were observed in mixed cultures: survival of A. salina was promoted in low G. aponina populations, while enhanced toxicity of G. breve to A. salina occurred at higher culture populations. Unialgal G. aponina cultures exerted no adverse effects on A. salina. The apparent protective effect is thought to result from the observed change in G. breve morphology (motile to sessile); toxicity was the result of enhanced toxin release by cytolyzed G. breve cells. In dose-response studies, aponin exhibited no adverse effect on A. salina at concentrations (1 unit) that were deleterious to G. breve. However, at higher applied levels (4--6 units), mortality was substantial (greater than 70%) after 48 hr of incubation. Probit analysis yielded an apparent LD50 of 2.3 units, where 1 unit was that amount required to cytolyze 50% of the G. breve cells (2000 cells/ml) after 20 hr of incubation.

Animals↗
PubMed2005

High-resolution diffusion tensor imaging of human patellar cartilage: feasibility and preliminary findings.

MR diffusion tensor imaging (DTI) was used to analyze the microstructural properties of articular cartilage. Human patellar cartilage-on-bone samples were imaged at 9.4T using a diffusion-weighted SE sequence (12 gradient directions, resolution = 39 x 78 x 1500 microm(3)). Voxel-based maps of the mean diffusivity, fractional anisotropy (FA), and eigenvectors were calculated. The mean diffusivity decreased from the surface (1.45 x 10(-3) mm(2)/s) to the tide mark (0.68 x 10(-3) mm(2)/s). The FA was low (0.04-0.28) and had local maxima near the surface and in the portion of the cartilage corresponding to the radial layer. The eigenvector corresponding to the largest eigenvalue showed a distinct zonal pattern, being oriented tangentially and radially in the upper and lower portions of the cartilage, respectively. The findings correspond to current scanning electron microscopy (SEM) data on the zonal architecture of cartilage. The eigenvector maps appear to reflect the alignment of the collagenous fibers in cartilage. In view of current efforts to develop and evaluate structure-modifying therapeutic approaches in osteoarthritis (OA), DTI may offer a tool to assess the structural properties of cartilage.

Anisotropy↗
PubMed1994

Characteristics of paralytic shellfish poisoning toxins derived from short-necked clams (Tapes japonica) in Mikawa Bay.

A "red tide" bloom of Alexandrium tamarense occurred in Mikawa Bay in April 1991. In association with this, paralytic shellfish poisoning toxin was detected in short-necked clams by mouse bioassay. High performance liquid chromatography analysis demonstrated large quantities of the N-sulfocarbamoyl toxins, C1, and C2 (approximately 90% of the total toxins), whose latent potency was confirmed by treatment with boiling at low pH.

Animals↗
PubMed1994

Growth and toxin production of the toxic dinoflagellate Pyrodinium bahamense var. compressum in laboratory cultures.

Toxin production of a Malaysian isolate of the toxic red tide dinoflagellate Pyrodinium bahamense var. compressum was investigated at various stages of the batch culture growth cycle and under growth conditions affected by temperature, salinity, and light intensity variations. In all the experiments conducted, only 5 toxins were ever detected. Neosaxitoxin (NEO) and gonyautoxin V (GTX5) made up 80 mole percent or more of the cellular toxin content and saxitoxin (STX), GTX6 and decarbamoylsaxitoxin (dcSTX) made up the remainder. No gonyautoxins I-IV or C toxins were ever detected. In nutrient-replete batch cultures, toxin content rapidly peaked during early exponential phase and just as rapidly declined prior to the onset of plateau phase. Temperature had a marked effect on toxin content, which increased 3-fold as the temperature decreased from the optimum of 28 degrees C to 22 degrees C. Toxin content was constant at salinities of 24% or higher, but increased 3-fold at 20%. Toxin content decreased 2-fold and chlorophyll content increased 3-fold when light intensity was reduced from 90 to 15 microE m-2 s-1. This accompanied a 30% decrease in growth rate. Toxin composition (mole % individual toxin cell-1) remained constant throughout the course of the nutrient-replete culture and during growth at various salinities, but varied significantly with temperature and light intensity changes. At 22 degrees C, GTX5 was 25 mole % and NEO was 65 mole %, while at 34 degrees C, GTX5 increased to 55 mole % and NEO decreased proportionally to 40 mole %. When light intensity was reduced from 90 to 15 microE m-2 s-1, NEO decreased from 55 to 38 mole %, while GTX5 increased from 40 to 58 mole %. These data suggest that low light and high temperature both somehow enhance sulfo-transferase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Complex behavior of marine animal tissue extracts in the competitive binding assay of brevetoxins with rat brain synaptosomes.

Brevetoxins are produced by the marine dinoflagellate Ptychodiscus brevis, an organism linked to red tide outbreaks, and the accompanying toxicity to marine animals and to neurotoxic shellfish poisoning in humans. Brevetoxins bind with high affinity to voltage-sensitive sodium channels and cause increased sodium ion conductance and nerve cell depolarization. The brevetoxin competitive binding assay with tritium-labeled brevetoxin 3 (3H-PbTx-3) and rat brain synaptosomes is a sensitive and specific assay for pure brevetoxins. Here we report that extracts of manatee, turtle, fish, and clam tissues contain components that interfere with the assay by cooperative, noncompetitive inhibition of 3H-PbTx-3 specific binding and increased nonspecific binding to synaptosomes. By determining the "apparent" toxin concentration ("[Toxin]") in the extract at several assay concentrations, a reasonable correction for the complex inhibition could be made using a semilog plot to extrapolate [Toxin] to zero extract concentration to obtain [Toxin]0. Spiking 4 extracts with 60 nM PbTx-3 caused [Toxin]0 to increase by 41 +/- 8 nM, indicating that the noncompetitive components did not prevent the assay of toxin but did reduce the accuracy of the result. Fourfold repetition of the assay of 4 samples gave standard deviations of 25 to 60% of the value of [Toxin]0, so the error can be fairly large, especially for samples with little toxin. Purification of an extract with a 1 g sample prep column of C-18 decreased the complex inhibition by about 3-fold but did not eliminate interference in the assay.

Animals↗
PubMed1993

Solid-phase radioreceptor assay for paralytic shellfish toxins.

Sodium channels obtained from rat brain membrane preparations were coated onto microtiter plates and used to develop a direct solid-phase binding assay. The tritiated sodium channel blocker saxitoxin ([3H]-saxitoxin; STX) was used to detect toxins in paralytic shellfish poisoning (PSP) by measuring the competitive displacement of other toxins. With this assay the amount of STX and tetrodotoxin needed to displace 50% of bound [3H]STX was 1.7 and 1.76 ng/ml for buffer samples, respectively. In the direct solid-phase binding assays, the PSP toxins were effectively bound to the rat brain membranes. The IC50 of this assay for different PSP toxin solutions obtained from mussels contaminated in red tides ranged from 0.03 to 0.30 ng/ml. Therefore, this assay represents a potentially useful method for the detection of toxin-contaminated mussels.

Animals↗
PubMed1999

Evaluation of the contamination of marine algae (Seaweed) from the St. Lawrence River and likely to be consumed by humans.

The goal of the study was to assess the contamination of marine algae (seaweeds) growing in the St. Lawrence River estuary and Gulf of St. Lawrence and to evaluate the risks to human health from the consumption of these algae. Algae were collected by hand at low tide. A total of 10 sites on the north and south shores of the St. Lawrence as well as in Baie des Chaleurs were sampled. The most frequently collected species of algae were Fucus vesiculosus, Ascophyllum nodosum, Laminaria longicruris, Palmaria palmata, Ulva lactuca, and Fucus distichus. Alga samples were analyzed for metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn), iodine, and organochlorines. A risk assessment was performed using risk factors (e.g., RfD of the U.S. EPA, ADI of Health Canada, etc.). In general, concentrations in St. Lawrence algae were not very high. This was especially true for mercury and the organochlorines, concentrations of which were very low or below detection limits. Consequently, health risks associated with these compounds in St. Lawrence algae were very low. Iodine concentration, on the other hand, could be of concern with regard to human health. Regular consumption of algae, especially of Laminaria sp., could result in levels of iodine sufficient to cause thyroid problems. For regular consumers, it would be preferable to choose species with low iodine concentrations, such as U. lactuca and P. palmata, in order to prevent potential problems. Furthermore, it would also be important to assess whether preparation for consumption or cooking affects the iodine content of algae. Algae consumption may also have beneficial health effects. Scientific literature has shown that it is a good source of fiber and vitamins, especially vitamin B12.

Environmental Exposure↗
PubMed1998

Effects of thyrotropin-releasing hormone and its metabolites, Cyclo(His-Pro) and TRH-OH, on growth hormone and prolactin synthesis in primary cultured pituitary cells of the common carp, Cyprinus carpio.

The effects of thyrotropin-releasing hormone (TRH) and its metabolites, cyclo(His-Pro) and TRH-OH, on growth hormone (GH) and prolactin (PRL) synthesis were investigated using primary cultured pituitary cells of the common carp, Cyprinus carpio. The effects of these pep tides on GH and PRL were compared to those of human GH-releasing hormone (hGHRH) and somatostatin (somatotropin-releasing inhibiting factor; SRIF). GH and PRL synthesis were determined by measuring the incorporation of [3H]leucine into GH and PRL. TRH stimulated the release of newly synthesized GH and PRL, but not thyroid-stimulating hormone. In addition, TRH stimulated a dose-related increase in the release of newly synthesized GH and PRL at 10(-9) to 10(-7) M. Cyclo(His-Pro) stimulated the release of newly synthesized GH dose- dependently. TRH, cyclo(His-Pro), and hGHRH stimulated GH synthesis, while SRIF inhibited this at 10(-7) M. The release of newly synthesized PRL into culture medium was also stimulated by TRH and hGHRH, but inhibited by SRIF. PRL synthesis was not affected by TRH-OH and cyclo(His-Pro). Intracellular contents of GH and PRL in the pituitary did not change significantly. The present study demonstrates that TRH plays an important role in both GH and PRL synthesis and release. This is the first report in which the effects of cyclo(His-Pro) on GH synthesis in teleosts are demonstrated.

Animals↗
PubMed2002

Ranking the benefits of biodiversity: an exploration of relative values.

Public concern about the alarmingly high rate of biodiversity loss has not been matched by public willingness to bear boundless costs to stem the tide of extinction. Because resources for conservation are limited, setting conservation priorities to use those resources effectively is crucial. To do so in a way that addresses people's most pressing concerns about biodiversity loss, managers and policy makers must understand those concerns. This study investigates preferences for an array of benefits associated with biodiversity and wildlife and the relative importance to people of each. A survey was administered to a sample of the US population to explore public preferences for types of benefits often associated with biodiversity: utilitarian (commodity and recreation), ecological (certain and uncertain), aesthetic, symbolic, and humanistic. Respondents were asked to rank hypothetical species presented in choice sets of three species, each described simply in terms of one type of benefit. A rank-ordered multinomial logit model was estimated to establish a ranking of the benefits and evaluate the sensitivity of the ranking to socio-demographic variables. The means of the sample predictions indicated the relative importance of each type of benefit. Confidence intervals were constructed to evaluate the extent to which the ranks could be distinguished from one another. Ecological functions were most important to survey respondents; commodity-based benefits and human attributes were of moderate importance; and recreation, aesthetics, and symbolic references in literature and art appeared to be least important.

Animals↗
PubMed2001

An early bone tool industry from the Middle Stone Age at Blombos Cave, South Africa: implications for the origins of modern human behaviour, symbolism and language.

Twenty-eight bone tools were recovered in situ from ca. 70 ka year old Middle Stone Age levels at Blombos Cave between 1992 and 2000. These tools are securely provenienced and are the largest collection to come from a single African Middle Stone Age site. Detailed analyses show that tool production methods follow a sequence of deliberate technical choices starting with blank production, the use of various shaping methods and the final finishing of the artefact to produce "awls" and "projectile points". Tool production processes in the Middle Stone Age at Blombos Cave conform to generally accepted descriptions of "formal" techniques of bone tool manufacture. Comparisons with similar bone tools from the Later Stone Age at Blombos Cave, other Cape sites and ethnographic collections show that although shaping methods are different, the planning and execution of bone tool manufacture in the Middle Stone Age is consistent with that in the late Holocene. The bone tool collection from Blombos Cave is remarkable because bone tools are rarely found in African Middle or Later Stone Age sites before ca. 25 ka. Scarcity of early bone tools is cited as one strand of evidence supporting models for nonmodern behaviour linked to a lack of modern technological or cognitive capacity before ca. 50 ka. Bone artefacts are a regular feature in European sites after ca. 40 ka, are closely associated with the arrival of anatomically modern humans and are a key behavioural marker of the Upper Palaeolithic "symbolic explosion" linked to the evolution of modern behaviour. Taken together with recent finds from Klasies River, Katanda and other African Middle Stone Age sites the Blombos Cave evidence for formal bone working, deliberate engraving on ochre, production of finely made bifacial points and sophisticated subsistence strategies is turning the tide in favour of models positing behavioural modernity in Africa at a time far earlier than previously accepted.

Anthropology, Physical↗