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PubMed2006

Algae-bacteria interactions and their effects on aggregation and organic matter flux in the sea.

Aggregation of algae, mainly of diatoms, is an important process in marine pelagic systems, often terminating phytoplankton blooms and leading to the sinking of particulate organic matter in the form of marine snow. This process has been studied extensively, but the specific role of heterotrophic bacteria has largely been neglected, mainly because field studies and most experimental work were performed under non-axenic conditions. We tested the hypothesis that algae-bacteria interactions are instrumental in aggregate dynamics and organic matter flux. A series of aggregation experiments has been carried out in rolling tanks with two marine diatoms typical of temperate regions (Skeletonema costatum and Thalassiosira rotula) in an axenic treatment and one inoculated with marine bacteria. Exponentially growing S. costatum and T. rotula exhibited distinctly different aggregation behavior. This was reflected by their strikingly different release of dissolved organic matter (DOM), transparent exopolymer particles (TEP) and protein-containing particles (CSP), as well as their bacterial biodegradability and recalcitrance. Cells of S. costatum aggregated only little and their bacterial colonization remained low. Dissolved organic matter, TEP and CSP released by this alga were largely consumed by free-living bacteria. In contrast, T. rotula aggregated rapidly and DOM, TEP and CSP released resisted bacterial consumption. Experiments conducted with T. rotula cultures in the stationary growth phase, however, showed rapid bacterial colonization and decomposition of algal cells. Our study highlights the importance of heterotrophic bacteria to control the development and aggregation of phytoplankton in marine systems.

Bacteria↗
PubMed2006

Whole genome analysis of the marine Bacteroidetes'Gramella forsetii' reveals adaptations to degradation of polymeric organic matter.

Members of the Bacteroidetes, formerly known as the Cytophaga-Flavobacteria-Bacteroides (CFB) phylum, are among the major taxa of marine heterotrophic bacterioplankton frequently found on macroscopic organic matter particles (marine snow). In addition, they have been shown to also represent a significant part of free-living microbial assemblages in nutrient-rich microenvironments. Their abundance and distribution pattern in combination with enzymatic activity studies has led to the notion that organisms of this group are specialists for degradation of high molecular weight compounds in both the dissolved and particulate fraction of the marine organic matter pool, implying a major role of Bacteroidetes in the marine carbon cycle. Despite their ecological importance, comprehensive molecular data on organisms of this group have been scarce so far. Here we report on the first whole genome analysis of a marine Bacteroidetes representative, 'Gramella forsetii' KT0803. Functional analysis of the predicted proteome disclosed several traits which in joint consideration suggest a clear adaptation of this marine Bacteroidetes representative to the degradation of high molecular weight organic matter, such as a substantial suite of genes encoding hydrolytic enzymes, a predicted preference for polymeric carbon sources and a distinct capability for surface adhesion.

Adaptation, Physiological↗
PubMed1975

Effects of dopamine on sinus rate and ventricular contractile force of the dog heart in vitro and in vivo.

1 Experiments were carried out on dog isolated papillary muscle and sinus node preparations perfused with arterial blood from a donor dog. The chronotropic and inotropic effects of dopamine were analysed by using reserpine, desmethylimipramine (DMI), cocaine and phenoxybenzamine, and the relative chronotropic and inotropic effects defined, the results being compared with those for noradrenaline (NA). 2 The effects of dopamine administered intra-arterially into the isolated preparations were reduced by pretreatment of animals with reserpine both in the papillary muscle and sinus node. The chronotropic effects, however, were affected less by pretreatment with reserpine than were the inotropic effects. 3 Desmethylimipramine (DMI) reduced the inotropic and chronotropic effects of dopamine, and enhanced the effects of NA and nerve stimulation; the chronotropic effects of the amines were less affected than the inotropic effects. 4 Cocaine enhanced considerably the inotropic and chronotropic effects of NA, and decreased the inotropic but not the chronotropic effect of dopamine. 5 Phenoxybenzamine enhanced the inotropic effects of dopamine, NA and nerve stimulation, but did not affect the chronotropic effects of the amines. 6 When dopamine (1 to 300 mug/kg) was administered intravenously to the donor dog, it increased preferentially the contractile force of the ventricular myocardium with a comparatively small change of the sinus rate in the isolated preparations as well as in the heart in vivo. NA (0.1 to 10 mug/kg) caused effects similar to those of dopamine. The maximal inotropic responses to these catecholamines were reached with lower doses than the chronotropic ones. 7 It is concluded that both the positive inotropic and the positive chronotropic responses to dopamine are mediated partially by a direct and partially by an indirect stimulant effect on beta-adrenoceptors in the dog heart. The present results suggest that the difference in activity of dopamine and NA between the ventricular myocardium and the sinus node may be ascribed to the unequal innervation with adrenergic nerve fibres of the atrium and the ventricle (Furnival, Linden & Snow, 1971). The sinus node which is densely innervated by adrenergic nerve fibres may inactivate noradrenaline and dopamine more effectively than the ventricular myocardium through the uptake into the nerve and thereby be less sensitive to the exogenous catecholamines.

Animals↗
PubMed1983

Partial hydatidiform mole: ultrasonographic features.

Four patients with partial hyatidiform mole managed at the Queen Mary Hospital, Hong Kong, are described. The diagnosis of blighted ovum or missed abortion was made on the sonographic findings prior to suction evacuation. The dominant features in these cases consisted of a relatively large central transonic area bearing the appearance of an empty gestational sac and surrounded by a thick rim of low-level placenta-like echoes; in contrast with the case of the blighted ovum, a well-defined echogenic sac wall is absent. In another 9 patients with molar pregnancy managed during the same period, the more typical 'snow-storm' vesicular appearance was present. It was concluded that the anembryonic appearance described should alert the sonologist and clinician to the possible diagnosis of partial hydatitiform mole. The evacuated material from the uterine cavity should be examined morphologically and if possible cytogenetically.

Adult↗
PubMedDate not supplied

Cryotherapy with solid carbon dioxide in the treatment of nevus flammeus.

Thirty-five infants with nevus flammeus were treated with carbon dioxide snow at intervals of two weeks. The treatment was initiated between the first and eleventh week, and improvement was found to be best when started between the age of 3 and 6 weeks. The result was excellent in 8 cases, good in 11, fair in 12, and poor in 4.

Age Factors↗
PubMed2006

Weather and emergency room visits for migraine headaches in Ottawa, Canada.

BACKGROUND: Self-reported surveys have indicated that weather can trigger migraine headaches. However, to date, we know of no previous study that has examined the relationship between weather and emergency room (ER) visits for this condition. OBJECTIVE: To examine associations between ER visits for migraines and selected meteorological conditions within the 24 hours preceding the visit. DESIGN AND METHODS: A case-crossover design was used to study 4039 visits for migraines (ICD-9: 346) that occurred at an Ottawa hospital between 1993 and 2000. Meteorological conditions were defined using hourly readings from a fixed-site monitoring station. Conditional logistic regression was used to compare the occurrence of meteorological conditions during the 24 hours leading up to the time of the visit to control periods occurring 1 week before and after. RESULTS: Precipitation-related weather events (fog, snow, rain, thunder) were not associated with migraine visits. Similarly, no associations were observed with changes in atmospheric pressure, wind speed, and relative humidity during the 24 hours preceding presentation. No statistically significant differences in the frequency distribution of clusters defined by relative humidity, atmospheric pressure, and temperature were found between case and control intervals. Conversely, a mean wind speed in excess of 19 km per hour was associated with a reduction in ER visits 8 to 12 hours later. CONCLUSIONS: Our findings provide little support for the hypothesis that ER visits for migraines are related to weather conditions occurring within the 24 hours preceding presentation. These results should be interpreted cautiously as some comparisons are based on a small number of cases, and ER visits for migraine may represent a highly selective group of patients who suffer from this condition.

Adult↗
PubMed1990

Initiating ethanol drinking in a simian social group in a naturalistic setting.

We examined in nine group-living, male Japanese Snow monkeys the initiation of alcohol-drinking behavior in an enriched environment where both social and nonsocial stimuli could influence drinking. The monkeys usually could move freely between an indoor shelter and a large outdoor corral, which contained three drinkometers. During daily 2-hr sessions in pre- and post-training periods (with food and water available ad libitum), the drinkometers held (on different days) Koolaid-saccharin, water, water with 5% ethanol, Koolaid-saccharin with 5% ethanol, or Koolaid-sucrose with acetic acid (matched in calories and palatability to Koolaid-saccharin with 5% ethanol). Between pre- and post-training periods was a long training period, in which Koolaid-saccharin with various ethanol concentrations was presented with the daily food ration in 2-hr drinking sessions. On other selected training days, water with 5% ethanol was presented. During training sessions some monkeys drank high doses; others did not. During the period of peak drinking, the daily mean ethanol consumption ranged among animals from 0.54-1.99 ml/kg. Blood ethanol concentrations then sometimes exceeded 100 mg/dl. During the post-training period, with return to ad libitum food and water, consumption declined from these peaks, but remained significantly higher than pretraining consumption; the ethanol solution was established as a reinforcer. Monkeys differed significantly in the extent of this pre/post increase. In both pre- and post-training periods, consumption was significantly greater when all three drinkometers operated, compared with only one. On pretraining days when only one drinkometer operated, more dominant animals drank significantly more than less dominant animals; this difference disappeared by the post-training period, as less dominant animals learned to use the drinkometers at times when the dominant animals eschewed the machines. Pretraining consumption did not predict (among animals) post-training consumption. Before, during, and after training, these animals drank less of both alcohol and control solutions than did members of another species, which we had studied in smaller indoor pens. We discuss possible explanations and implications.

Alcohol Drinking↗
PubMed2006

Semiparametric regression in capture-recapture modeling.

Capture-recapture models were developed to estimate survival using data arising from marking and monitoring wild animals over time. Variation in survival may be explained by incorporating relevant covariates. We propose nonparametric and semiparametric regression methods for estimating survival in capture-recapture models. A fully Bayesian approach using Markov chain Monte Carlo simulations was employed to estimate the model parameters. The work is illustrated by a study of Snow petrels, in which survival probabilities are expressed as nonlinear functions of a climate covariate, using data from a 40-year study on marked individuals, nesting at Petrels Island, Terre Adélie.

Animals↗
PubMed1977

N-methyl-N'-nitro-N-nitrosoguanidine and UV induced mutants of the dinoflagellate Crypthecodinium cohnii.

Mutant strains were chemically induced by treatment with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) and UV irradiation. UV and NTG mutation rates were obtained that were both consistent with the organism being haploid. Three types of mutants were produced: (a) strains deficient in both beta- and gamma-carotene, the only carotenoids found in the wild type; phenotypes include albinos (translucent, dull white, "snow white") and cream-colored on agar as compared to the yellow-orange color of wild type colonies; (b) strains requiring adenine, guanine or cytosine in addition to the minimal medium for growth; (c) mutants that grow at a rate less than 40% of the wild type in minimal medium.

Animals↗
PubMedDate not supplied

Controlling harmful algal blooms through clay flocculation.

The potential use of clays to control harmful algal blooms (HABs) has been explored in East Asia, Australia, the United States, and Sweden. In Japan and South Korea, minerals such as montmorillonite, kaolinite, and yellow loess, have already been used in the field effectively, to protect fish mariculture from Cochlodinium spp. and other blooms. Cell removal occurs through the flocculation of algal and mineral particles, leading to the formation of larger aggregates (i.e. marine snow), which rapidly settle and further entrain cells during their descent. In the U.S., several clays and clay-rich sediments have shown high removal abilities (e.g. > 80% cell removal efficiency) against Karenia brevis, Heterosigma akashiwo, Pfiesteria piscicida and Aureococcus anophagefferens. In some cases, the removal ability of certain clays was further enhanced with chemical flocculants, such as polyaluminum chloride (PAC), to increase their adhesiveness. However, cell removal was also affected by bloom concentration, salinity, and mixing. Cell mortality was observed after clay addition, and increased with increasing clay concentration, and prolonged exposure to clays in the settled layer. Mesocosm, field enclosure, and flume experiments were also conducted to address cell removal with increasing scale and flow, water-column impacts, and the possible benthic effects from clay addition. Results from these studies will be presented, especially those in regards to water quality, seawater chemistry, bottom erodibility and faunal impacts in the benthos. At this time, clay dispersal continues to be a promising method for controlling HABs and mitigating their impacts based on existing information and experimental data.

Aluminum Hydroxide↗
PubMed1997

Detection and in situ identification of representatives of a widely distributed new bacterial phylum.

16S rRNA gene libraries were prepared by polymerase chain reaction amplification and cloning from soil samples taken periodically from a field with genetically modified plants. Sequence analyses of the cloned rDNAs indicated that 140 of them clustered apart from known bacterial phyla. Based on 31 full sequences a new phylum could be defined. It includes Holophaga foetida, 'Geothrix fermentans' and Acidobacterium capsulatum as the only cultured species so far. Therefore, this line of descent was named the Holophagal Acidobacterium phylum. About 50 published partial sequences of cloned rDNAs retrieved from soil, freshwater sediments or activated sludge from different continents indicate the occurrence of further representatives of this phylum. Two specific hybridization probes were constructed for members of one of four subclusters. A careful data analysis revealed the importance and problems of identifying and dealing with artefacts such as chimeric structure when defining new phylogenetic groups based mainly upon cloned amplified rDNAs. For the first time, the presence of bacterial cells representing this group could be shown in soil, sediment, activated sludge and lake snow by in situ hybridization.

Bacteria↗
PubMed1984

Epidemiological investigations into multiple sclerosis in southern Hesse. II. The distribution of cases in relation to exogenous features.

In order to discover possible exogenous variables associated with a higher multiple sclerosis risk, the distribution of cases with definite and probable multiple sclerosis ascertained in the course of a micro-epidemiologic study in Southern Hesse was evaluated and compared with some environmental factors. The prevalence in 1980, the prevalence of cases with disease-onset within the region according to locality of onset and the rate of native Southern Hesse patients according to childhood residence all showed a similar geographical distribution, with the highest values in the south-eastern, mountainous part of the region. This district has a lower annual mean temperature, more annual snow-days and a higher annual precipitation compared to the remaining area. A statistical comparison revealed no association with industrial or agricultural activities, with a particular type of land use, with cattle, pig- or horse-breeding, or with sanitary or housing standards. On the other hand, a slight association with the soil type could be demonstrated, with higher rates on loam and clay subsoils when compared to predominantly sandy regions. Whether this finding has any significance or not remains to be clarified.

Agriculture↗
PubMed2004

HVAC--the importance of clean intake section and dry air filter in cold climate.

UNLABELLED: HVAC systems, if properly designed, installed, operated and maintained, will improve thermal conditions and air quality indoors. However, the success strongly depends on the design of the system and the quality of the components we use in our HVAC installations. Regrettably, several investigations have revealed that many HVAC installations have a lot of operational and maintenance problems, especially related to moisture, rain and snow entrainment. In short, it seems that too little attention is placed on the design of the intake section, despite the fact that there exists a large number of national and international guidelines and recommendations. This is a serious problem because the air intake is the initial component of the ventilation plant and as such the first line of defense against debris and other outdoor air pollutants. Unfortunately, the design is often an argued compromise between the architect, the civil engineer and the HVAC engineer. In the future, the technical, hygienic and microbiological feature of air intakes must be better ensured in order to avoid the air intake becoming a risk component as regards contamination and indoor air quality. Further, it seems that the magnitude of the problem is not well known, or recognized, by the building designers, engineers and professionals involved in the construction and operation of buildings. This fact needs to be addressed more seriously, because obviously there is a big difference between the idealistic architectonic design, engineering intentions and the real life situation. PRACTICAL IMPLICATIONS: Several practical recommendations for design and operation of HVAC systems are presented. Following the recommendations will result in less pollution from the HVAC-system and increased indoor environmental quality.

Air Conditioning↗
PubMed1976

Influence of maturation status and tooth type of permanent teeth upon electrometric and thermal pulp testing.

The threshold values of developing teeth were determined for two commonly used electrometric pulp testers (Siemens Sirotest and Bofors Pulp Tester) and a new thermal test based on carbon dioxide snow (Odontotest). The teeth examined were divided into 7 stages according to maturation status. This study showed that teeth in Stages 3-5, i.e. until completion of root formation, show an increased electrometric threshold value. The Siemens tester appeared to be equal to the Bofors tester with regard to reliability. The Odontotest was the most reliable method examined, giving a consistent positive response in all examined teeth.

Adolescent↗
PubMed1998

Health aspects of Antarctic tourism.

Increasing numbers of seaborne tourists are visiting Antarctica, with most coming from the United States (3503 in 1996-97), Germany (777), and Australia (680; cf. 356 in 1994-95 and 410 in 1995-96). The impression among travel medicine clinicians is that, each year, more prospective travelers seek advice about the health demands of this type of adventure, mostly relating to fitness for travel, exposure to extreme cold, hazards in ice and snow, and other potential health risks. This is a recent phenomenon. While a regular shipping service had been established between the Falklands and the subantarctic islands of South Georgia and the South Shetlands by 1924, the first documented tourists accompanied an Argentine expedition to the South Orkneys in 1933.1 Commercial airline flights over these islands and the Antarctic Peninsula began in 1956, from Chile, and recreational cruises to the Peninsula began in 1958. Tourist numbers subsequently grew slowly, for what was clearly an exclusive and very expensive undertaking, with few ships available for these hazardous voyages. From 1957 to 1993, 37,000 tourists visited by sea, most seeing only the Peninsula.2 The dramatic recent growth in numbers is a consequence of the collapse of the Soviet Union. The small fleet of ice-strengthened research vessels and working icebreakers, which was made redundant by withdrawal of central government support from isolated communities and military activities along the northern coast of Siberia (and from Antarctic research bases), now accounts for the bulk of charter-cruise tourism to Antarctica, at competitive prices. According to the International Association of Antarctica Tour Operators,3 7322 people traveled to Antarctica on commercially organized voyages in the 1996-97 season, and a record 10,000 shipborne visitors were expected for the 1997-98 season (November-March), traveling mainly from South America to the Peninsula on 15 ice-reinforced vessels, each carrying between 36 and 180 passengers. Most tours embark from Ushuaia in southern Argentina, or Punta Arenas in Chile, although occasional cruises leave from Australia, New Zealand, or even South Africa.

Adolescent↗
PubMedDate not supplied

Noble gas and major element constraints on the water dynamics in an alpine floodplain.

The hydrogeological system of an ecologically sensitive alpine floodplain in the Valle di Blenio, Switzerland, was investigated using hydrochemical and 3H-3He dating methods. Water samples from six wells and from different surface locations were analyzed. The analysis of the concentrations of major ions in conjunction with age determination by the 3H-3He-method allowed the main hydrological properties of the system to be consistently characterized. Two geochemically distinct water zones can be distinguished: Ca-SO4-dominated water from the main river and Ca-HCO3-dominated floodplain water. The floodplain water component characterizes the whole floodplain including the surficial hillslope drainage system. Within the ground water samples, two spatially and temporally different types of water can be determined. A younger (age < 1.5 years), less mineralized water is found in the upper part of the aquifer during the summer season. The underlying aquifer zone contains older and more highly mineralized water. However, the general hydrochemical characterization of both types of ground water is similar. In winter, the water ages increase with decreasing ground water levels. Because precipitation is stored temporarily in the snow cover, the contribution of the younger near-surface ground water decreases, resulting in higher apparent water ages and higher mineralization in the upper zone of the aquifer. Water exchange between the main river and the ground water system is limited to ground water exfiltration from the shallow aquifer zone, whereas the hydrochemical separation of the deeper aquifer zone indicates the isolation of the deeper ground water from the main river.

Geological Phenomena↗
PubMedDate not supplied

Numerical investigation of road salt impact on an urban wellfield.

The impact of road salt on a wellfield in a complex glacial moraine aquifer system is studied by numerical simulation. The moraine underlies an extensive urban and industrial landscape, which draws its water supply from >20 wellfields, several of which are approaching or have exceeded the drinking water limit for chloride. The study investigates the mechanisms of road salt infiltration, storage, and transport in the subsurface and assesses the effectiveness of mitigation measures designed to reduce the impact. The three-dimensional transport model accounts for increases in salt loading, as well as growth of the urbanized area and road network over the past 50 years. The simulations, which focus on one impacted wellfield, show chloride plumes originating mainly at arterial roads and migrating through aquitard windows into the water supply aquifers. The results suggest that the aquifer system contains a large and heterogeneously distributed mass of chloride and that concentrations in the aquifer can be substantially higher than the concentrations in the well water. Future impact scenarios indicate that although the system responds rapidly to reductions in salt loading, the residual chloride mass may take decades to flush out, even if road salting were discontinued. The implications with respect to urban wellfields in typical snow-belt areas are discussed.

Chlorides↗
PubMed1989

The biological effects of UV-B on the eye.

The adverse effects of ultraviolet-B (UV-B) radiation on the eye have been suspected but only recently have they been quantified by epidemiologic studies in humans. These studies became possible as methods to qualify individual ocular UV-B exposure were developed. A consistent dose-dependent association between ocular UV-B exposure and two common types of cataract (cortical and posterior subcapsular) has been shown. Although suggested by experimental studies, at present, evidence does not exist to link UV-B exposure to senile macular degeneration. Ocular exposure to UV-B is also associated with several corneal changes, pterygium, climatic droplet keratopathy, and acute photokeratitis (snow blindness). Significant reduction in ocular UV-B exposure results from the use of eyeglasses and hats.

Cataract↗