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At least 19 recordsLinked to original sources

PubMed1976

Fecal indicator bacteria persistence under natural conditions in an ice-covered river.

Total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) survival characteristics, under natural conditions at 0 degrees C in an ice-covered river, were examined during February and March 1975. The membrane filter (MF) technique was used throughout the study, and the multiple-tube (MPN) method was used in parallel on three preselected days for comparative recovery of these bacteria. Survival was studied at seven sample stations downstream from all domestic pollution sources in a 317-km reach of the river having 7.1 days mean flow time (range of 6.0 to 9.1 days). The mean indicator bacteria densities decreased continuously at successive stations in this reach and, after adjustment for dilution, the most rapid die-off was found to occur during the first 1.9 days, followed by a slower decrease. After 7.1 days, the relative survival was TC less than FC less than FS, with 8.4%, 15.7%, and 32.8% of the initial populations remaining viable, respectively. These rates are higher than previously reported and suggest that the highest survival rates for these bacteria in receiving streams can be expected at 0 degree C under ice cover. Additionally, the FC-FS ratio was greater than 5 at all stations, indicating that this ratio may be useable for determining the source of fecal pollution in receiving streams for greater than 7 days flow time at low water temperatures. The MPN and MF methods gave comparable results for the TC and FS at all seven sample stations, with both the direct and verified MF counts within the 95% confidence limits of the respective MPNs in most samples, but generally lower than the MPN index. Although FC recovery on membrane filters was comparable results at stations near the pollution source. However, the results became more comparable with increasing flow time. The results of this study indicate that heat shock is a major factor in suppression of the FC counts on the membrane filters at 44.5 degree C. Heat shock may be minimized by extended incubation at 35 degrees C before exposure to the higher temperature.

Alaska↗

PubMed1992

Winter transport of Chernobyl radionuclides from a montane catchment to an ice-covered lake.

The amounts of 137Cs and 90Sr have been determined in the inflows and outflows of the Norwegian sub-alpine lake, Ovre Heimdalsvatn, in March/April during the period of ice-cover, when discharge is extremely stable. The lake is situated in an area contaminated by Chernobyl fallout. The transported course particulate plant material has been collected in traps; the particles and colloids have been removed from water samples by cross-flow ultrafiltration. On the basis of radionuclide inputs and outputs, lake budget calculations have been made for 137Cs and 90Sr during the period of ice-cover. Daily transport of radionuclides is considerably less than that observed during the spring snowmelt period when discharges are high. Size distribution patterns of Cs and Sr observed during winter are compared with previously published data from the same lake during the spring spate. The retention of 137Cs is similar in winter and spring, but retention of 90Sr is greater in winter.

Accidents↗

PubMed1979

Survival of enteric viruses under natural conditions in a subarctic river.

The survival of enteric viruses was studied in the vicinity of Fairbanks, Alaska at selected stations along a 317-km section of the Tanana River. This section was located downstream from all known domestic wastewater sources and was effectively sealed by a total ice cover. The mean flow time through the region was 7.1 days, during which initial viral population showed a relative survival rate of 34%. The tracing of native viruses at such great distances in the complete absence of other point and nonpoint viral sources has not been previously reported. Of the two methods of virus concentration used, viral recoveries from the disk adsorption virus elution procedure were far greater than those achieved with the Aquella system employed at that time. The fact the ratio of enteric viruses to fecal indicator bacteria was not constant clearly inferred that these bacteria were not an effectual measure of virus concentration. The persistence of fecal coliforms and fecal streptococci, however, attested to the microbiological health risk involved.

Alaska↗

PubMed1991

Precautionary street crossing by elderly pedestrians.

Street crossing behavior of pedestrians was observed under varying roadway conditions and traffic volumes. The extent to which pedestrians checked for oncoming traffic before crossing signal controlled intersections on a dangerous downtown street was observed. Contrary to the stereotypical portrayal of older pedestrians as being less cognizant of the traffic environment, pedestrians in this study over the age of fifty years were the most cautious. Older pedestrians were also more cautious under the most potentially hazardous crossing conditions: when roadways were snow- or ice-covered and when traffic volumes were low or moderate, allowing vehicles to move rapidly through intersections.

Accidents, Traffic↗

PubMed1990

Mussel culture and the accumulation of domoic acid.

The cultured mussel industry of Prince Edward Island had never experienced a toxic disease problem until November of 1987. With the successful use of the long-line culture system, the yearly production of fresh mussels to the gourmet food market had risen to close to 3.2 million pounds (1.46 million kg) of product. The physiology of this sessile bivalve and its method of feeding and location in the estuary leave it prone to the accumulation of a widely distributed biotoxin. Eastern Prince Edward Island became the epicentre of domoic acid-intoxicated mussels as early as 10 November 1987 (retrospective samples) during an intense bloom of the diatom Nitzschia. Mussels were able to accumulate large amounts of the domoic acid with little effect on their own well-being. Despite being in low water temperatures (below 4 degrees C) and under thick ice cover, the levels of the toxin decreased and were undetectable in about 6 weeks. The following year the toxin was detected in much smaller amounts, and the levels of toxin accumulation demonstrated a variable lag time with the increase in concentration of Nitzschia available in the water column. The sales of Prince Edward Island cultured mussels have rebounded to about 140% of the pre-domoic acid crisis.

Animals↗

PubMed1977

A five-year study of mortality in a busy ski population.

A 5-year study of a busy ski population in Utah revealed a total at-risk period of approximately 3.5 million skier-days. While the morbidity (fractures, strains, sprains, and occasionally more severe injuries) associated with skiing is well recognized and considered by most physicians concerned to be distributed somewhat unevenly within the various skills of skiing, the authors have identified an exceedingly low mortality among the same population. Six individuals died as a result of injuries directly attributable to skiing. Three of these were considered to be advanced skiers and three were of intermediate skill. In three instances the environment was considered to play a role in the accident. Two of these victims were skiing out of control, one as a result of ice-covered snow and one as a result of speed in combination with a small jump. The third victim was crushed in an avalanche. One accident was completely unexplained, the skier having skied without apparent attempt at checking or change of course into a nonrecreational area. The two remaining skiers of intermediate skill both suffered injuries incident to falling forward with considerable force onto a relatively flat, hard snow surface. Notwithstanding the intense and sometimes prolonged exertion at relatively high altitudes (9,400 to 11,000 ft or 2.9 to 3.3 km), only one skier with a previous history of atherosclerotic heart disease died while skiing. One additional middle-aged skier with similar history died at the conclusion of the day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2026

Elevation-structured viral ecological strategies along glacier-fed rivers on the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau, a climate-vulnerable source of Asia's major rivers, harbors underexplored viral communities critical to ecosystem functions. By integrating 597 metagenomes from the Yangtze, Yellow, Lancang, and Yarlung Tsangpo rivers with 85 public available glacial metagenomes (Tibetan Glacier Genome and Gene catalog), we built the Glacier-to-River Virome Catalogue, encompassing 36,358 vOTUs and 897,250 viral protein clusters, to decode viral adaptation and ecological influence across elevation gradients. Our results reveal that high-altitude conditions favor viruses with elevated Guanine-Cytosine content, larger genomes and more cold-adaptation genes. A central finding is a systematic viral lifestyle shift from temperate in glaciated regions to lytic viruses downstream, accompanied with decline of pathogens carrying antibiotic resistance genes along the glacier-to-river gradients. Further, viral auxiliary metabolic genes transition from glacier nutrient scavenging (e.g., nitrogen and sulfur transporters) to downstream mineralization processes (e.g., denitrification) in plains highlights their role in biogeochemical cycling. These findings position viruses as pivotal regulators of microbial community structural and functional dynamics to glacier-to-river gradient change and biogeochemistry in the Qinghai-Tibet Plateau, providing critical insights into climate response in vulnerable Asian water towers.

Ice Cover↗

PubMed2025

Quaternary Glaciation Accelerates Speciation in Aquatic Snakes Through Recent Bottlenecks.

Climatic fluctuations during glacial periods have profoundly shaped the demographic history and gene flow dynamics of many taxa. This study integrated high-throughput sequencing of 67 individuals with comprehensive genomic analyses to investigate biogeographic patterns, genetic divergence and demographic trajectories in the Opisthotropis latouchii species complex, a group of mountain stream snakes distributed across Central China. Our analyses revealed substantial genetic divergence, identifying four distinct lineages, each confined to one of the four major mountain ranges in Central China, including one previously unrecognised species. These lineages exhibited distinct demographic signatures, with population bottlenecks occurring during Quaternary glaciations. Initial isolation in the glacial refugia of the southern regions of these mountains during the Late Pliocene was followed by postglacial expansions along a northward trajectory, with further divergence along a latitudinal gradient associated with mountain distribution. Notably, the mountain ranges of Central China acted as critical refugia during glacial periods, promoting rapid speciation, and as dispersal corridors during interglacial periods, facilitating range expansion and enabling recent gene flow. These findings highlight the profound impact of Quaternary climatic oscillations on genetic structure, demographic history and gene flow patterns of these endemic taxa.

Animals↗

PubMed2026

Experimental insights in taxon-specific functional responses to droughts in glacier-fed stream biofilms.

BACKGROUND: Glacier-fed streams are predicted to face increasingly frequent and intense droughts. However, the impacts of drought events on benthic biofilm, including bacteria, eukaryotes, and viruses, the dominating life form in glacier-fed streams, remain poorly understood. RESULTS: Using streamside flume mesocosms in the Swiss Alps, we grew glacier-fed stream biofilms over 103 days and exposed them to three droughts. Using a multi-omics approach (metagenomics, metatranscriptomics, and metaproteomics), we assessed the effects of a series of droughts on the taxonomy and metabolic activity of bacterial, eukaryotic, and viral metagenome-assembled genomes (MAGs). We found that the first drought (6 h) caused only minor changes, including mild upregulation of heterotrophic metabolism and signs of stress in diatoms. In contrast, the second drought (24 h) significantly altered both the composition and functionality of the microbiome, shifting phototrophic dominance from diatoms to Cyanobacteriota, while maintaining overall phototropic biomass and further upregulating the heterotrophic metabolism. Interestingly, a third 24 h drought had no detectable transcriptomic effect between pre- and post-drought conditions, suggesting a certain level of adaptive responses to droughts, but with the low diatom abundance being maintained. CONCLUSIONS: These findings indicate that glacier-fed biofilm microorganisms initially resisted short-term drought, but a second longer drought caused important shifts in their community structure, activity, and function. Climate-induced increases in drought frequency or duration may therefore have a lasting impact on microbial ecosystem functioning in glacier-fed streams. Video Abstract.

Biofilms↗

PubMed1976

Common-source epidemic of hepatitis due to glazed and iced pastries.

Sixty-one clinical cases of hepatitis occurred in Ogemaw County, Michigan, in late April and May 1968. The clustering of cases in time and the high attack rate for persons 10-19 years of age suggested a common source of exposure. Investigation implicated a local bakery, where one of the employees directly involved in the baking had had an icteric illness one month before the outbreak. Comparison of exposure histories of patients versus healthy family members established pastries covered with glaze or icing as the vehicle of infection. The glaze and icing were applied to the pastries after all baking had been completed. During the epidemic, immune serum globulin was given on a community-wide basis. No secondary cases of hepatitis were identified.

Adolescent↗

PubMed1992

Structural data suggest that the active and inactive forms of the RecA filament are not simply interconvertible.

We have used electron microscopy to examine the two major conformational states of the helical filament formed by the RecA protein of Escherichia coli. The compressed filament, formed in the absence of a nucleotide cofactor either as a self-polymer or on a single-stranded DNA molecule, is characterized in solution by about 6.1 subunits per turn of a 76 A pitch helix, and appears to be inactive with respect to all RecA activity. The active state of the filament, formed with ATP or an ATP analog on either a single or double-stranded DNA substrate, has about 6.2 subunits per turn of a 94 A pitch helix. Measurements of the contour length of RecA-covered single-stranded DNA circles in ice, formed in the absence of nucleotide cofactor, indicate that each RecA subunit binds five bases, in contrast to the three bases or base-pairs per subunit in the active state. The different stoichiometries of DNA binding suggests that the two polymeric forms are not interconvertible, as has been suggested on biochemical grounds. A three-dimensional reconstruction of the inactive state shows the same general features as the 83 A pitch filament present in the RecA crystal. This structural similarity and the fact that the crystal does not contain ATP or DNA suggests that the crystal structure is more similar to the compressed filament than the active, extended filament.

Adenosine Triphosphate↗

PubMed1992

Progression and regression of partial corneal involvement in the iridocorneal endothelial syndrome.

We have observed three women with partial corneal involvement in the ICE syndrome for over 10 years. During this time, the peripheral anterior synechiae progressed in all three, with glaucoma developing in one patient. In two patients, the abnormal endothelial cells spread to cover the entire posterior corneal surface; in the third, they disappeared entirely (ie, "the ICE melted"). The endothelial permeability to fluorescein remained abnormally low only in the two eyes with diffusely abnormal endothelium, increasing to normal in the third eye as the abnormal endothelium disappeared. The permeability in that eye had been abnormally low only in the superior half of the cornea, where the abnormal endothelium was. As the abnormal endothelium regressed, it was replaced by normal endothelium with a normal cell density similar to that of the opposite, uninvolved eye. Thus, over a 10-year period the partial endothelial involvement associated with the ICE syndrome progressed substantially in two patients and regressed dramatically in a third.

Adult↗

PubMed1990

Leukotrienes C4, D4, and E4 in fetal lamb tracheal fluid.

Previously, we demonstrated that either putative leukotriene receptor antagonists or a synthesis inhibitor markedly decreased pulmonary vascular resistance in the near-term fetal lamb and concluded that leukotrienes may play a role in maintaining the high pulmonary vascular resistance in the fetus. To further investigate the role of leukotrienes, we measured concentrations of leukotriene (LT) C4, LTD4, and LTE4 in 17 tracheal fluid samples from 8 of 9 near-term (129-139 days, term = 145 days), chronically-catheterized, fetal lambs during normoxia to evaluate their possible role in regulating resting tone and in seven of the nine before and during hypoxia to evaluate their possible role in hypoxic vasoconstriction. The tracheal fluid samples collected by gravity over 1-3 min, on ice, were immediately treated with cold ethanol, centrifuged, and the supernatant covered with N2 and stored in a -70 degrees C freezer for a maximum of 3 weeks. Purification and separation of leukotrienes was done by reverse-phase high performance liquid chromatography using a gradient elution method, and fractions corresponding to LTC4, LTD4, and LTE4 standards were quantified immediately by radioimmunoassay. During normoxia (descending aortic PaO2 2.9 +/- 0.3 kPa [21.5 +/- 2.5 mmHg]; mean +/- SD), all 3 leukotrienes were detected in 16 of the 17 samples: LTC4 29 +/- 28 pg/ml (range 0-119 pg/ml); LTD4 66 +/- 51 pg/ml (range 9-177 pg/ml); and LTE4 43 +/- 50 pg/ml (range 0-204 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1976

The "vanilla fudge" cyst.

A white cyst, partially covered by jet black splotches and streaks, had a surface appearance of vanilla fudge ice cream. Histologically, the cyst was lined with two distinctly different types of follicular epithelium--one identical to that of the infundibulum and the other to that of the matrix. The black pigment was melanin, produced by numerous dendritic melanocytes that were situated only in the region of the epithelium-resembling matrix.

Adult↗

PubMedDate not supplied

A new thermal shape memory Ti-Ni alloy stent covered with silicone.

An attempt was made to develop an airway stent for nonsurgical transluminal implantation using a bronchofiberscope. The stent is composed of a single wire with a diameter of 0.5 mm. The wire is made of thermal shape memory titanium nickel alloy, with a transition temperature of 25-30 degrees C. To avoid direct contact between the metal and the tissue, the wire is covered with a 300 microns thick coating of silicone. The stent is horseshoe shaped in cross-section. It is 15 mm in outer transverse diameter and 40 mm long. Ten stents were implanted in 10 dogs whose tracheal cartilages had been previously broken. The stents were first cooled in ice water to reduce their diameter and then inserted into the target site. The wire was warmed to body temperature and recovered its initial shape within 10 sec. The dogs were killed for examination between 1 week and 6 months after implantation. All the stents were located at the implantation sites and were patent. Tissue reactions, such as ulceration and granulation formation, were less severe than in those with previously implanted non-silicone covered stents. Microscopic observation showed that the wires became gradually covered with epithelium within 2 months. This transluminal technique for preserving airway patency shows promise for clinical application.

Alloys↗

PubMed1991

Simultaneous visualization of LDL receptor distribution and clathrin lattices on membranes torn from the upper surface of cultured cells.

We have developed a method for simultaneous visualization by electron microscopy of both the distribution of cell surface receptors and architectural features of the inner membrane surface, such as clathrin-coated pits. Electron microscope grids were covered with formvar and coated with poly-L-lysine. These grids were then placed on a piece of buffer-impregnated cellulose acetate membrane filter maintained at 4 degrees C on an ice bath. Cells of interest were grown on glass coverslips and incubated with either a ligand-gold or an antibody-gold conjugate specific for the membrane determinant of interest. The coverslip with gold-labeled cells was then overlaid on the grids and pressure was applied. When the grid was removed, large areas of the upper cell surface, which had labeled determinants, remained adherent to the formvar support. With the proper staining, both the gold particles and internal membrane features could be seen at the same time in the electron microscope. This method is rapid, does not require extensive experience with electron microscopic technique, and permits viewing of membrane samples that are large enough to perform quantitative analysis of gold distribution in relation to membrane specializations.

Animals↗

PubMed1979

Protein--water interactions. Heat capacity of the lysozyme--water system.

Calorimetric measurements of the heat capacity of the lysozyme-water system have been carried out over the full range of system composition at 25 degrees C. The partial specific heat capacity of the protein in dilute solution is 1.483 +/- 0.009 J K-1 g-1. The heat capacity of the dry protein is 1.26 +/- 0.01 J K-1 g-1. The system heat capacity responds linearly to change in composition from dilute solution to 0.38 g of water per g of protein (h) and is an irregular function at lower water content. The break in the heat capacity function at 0.38 h defines the amount of water needed to develop the equilibrium solution properties of lysozyme as being 300 molecules of water/protein molecule, just sufficient for monolayer coverage. The heat capacity behavior at low water content describes three hydration regions. The most tightly bound water (0-0.07 h), probably principally bound to charged groups, is characterized by a partial specific heat capacity of 2.3 J K-1 g-1, a value close to that for ice. A heat of reaction associated with proton redistribution is reflected in the heat capacity function for the low-hydration region. Between 0.07 and 0.25 h the heat capacity increases strongly, which is understood to reflect the growth of patches of water covering polar and adjacent nonpolar portions of the protein surface. The hydration shell is completed by condensation of solvent over the weak-interacting portions of the surface, in a process displaying a transition heat.

Calorimetry↗

PubMed1992

Cold destabilisation of enzymes.

The thermal stability profile of chymotrypsinogen has been investigated in the temperature range 230-340 K, with special emphasis on the phenomenon of cold instability. Differential scanning calorimetry was used to study the heat capacities of the native and denatured protein in undercooled solution and the results were combined with those obtained by spectrophotometry at ordinary temperatures. The partial heat capacities of both forms decrease with decreasing temperature, assuming negative values. In the experimentally accessible temperature range (above the spontaneous nucleation temperature of ice) the heat capacity difference delta C is found to be positive with a non-linear temperature dependence. delta C is predicted to change sign at some low temperature which cannot, however, be reached by experiment for chymotrypsinogen. In contrast to earlier studies, covering a much more limited temperature range and having to employ an additional destabilisation by means of pH and/or chaotropes, the present findings permit the construction of a more reliable thermodynamic stability profile and related properties. These differ in important details from those reported for other proteins, but based on measurements only in the neighbourhood of the heat-denaturation temperature. The thermodynamic characteristics are, however, in good agreement with earlier predictions and with recent low-temperature measurements on the tetrameric enzyme lactate dehydrogenase.

Calorimetry, Differential Scanning↗