Increased insensible water loss in newborn infants nursed under radiant heaters.
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Urine osmolality was studied in 38 babies nursed in conventional incubators or cots and 18 nursed under an overhead radiant heat shield. Among 50 babies receiving a similar fluid intake in the first 48 hours of life mean urinary osmolality was significantly higher in the radiant heater group. In babies weighing less than 1500 g a trend towards higher urinary osmolalities was recorded in those nursed under radiant heaters even though they had received amost double the fluid intake of the incubator group. Severe hypernatraemia occurred in four of the five babies weighing less than 1000 g who were nursed under radiant heaters but in none of the seven babies of similar birth weight nursed in incubators. These findings are consistent with previous observations of an increase in insensible water loss in babies nursed under radiant heaters and emphasise the importance of providing enough extra water for these infants and the need for close monitoring of their fluid balance. The latter may be done at the bedside by measuring urinary specific gravity with a hand refractometer. (+info)
Influence of crossdrafts on the performance of a biological safety cabinet.
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A biological safety cabinet was tested to determine the effect of crossdrafts (such as those created by normal laboratory activity or ventilation) upon the ability of the cabinet to protect both experiments and investigators. A simple crossdraft, controllable from 50 to 200 feet per min (fpm; 15.24 to 60.96 m/min), was created across the face of the unit. Modifications of standardized procedures involving controlled bacterial aerosol challenges provided stringent test conditions. Results indicated that, as the crossflow velocities exceeded 100 fpm, the ability of the cabinet to protect either experiments or investigators decreased logarithmically with increasing crossdraft speed. Because 100 fpm is an airspeed easily achieved by some air conditioning and heating vents (open windows and doorways may create velocities far in excess of 200 fpm), the proper placement of a biological safety cabinet within the laboratory--away from such disruptive air currents--is essential to satisfactory cabinet performance. (+info)
Nitrate removal in closed-system aquaculture by columnar denitrification.
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The columnar denitrification method of nitrate-nitrogen removal from high-density, closed system, salmonid aquaculture was investigated and found to be feasible. However, adequate chemical monitoring was found to be necessary for the optimization and quality control of this method. When methanol-carbon was not balanced with inlet nitrate-nitrogen, the column effluent became unsatisfactory for closed-system fish culture due to the presence of excess amounts of nitrite, ammonia, sulfide, and dissolved organic carbon. Sulfide production was also influenced by column maturity and residence time. Methane-carbon was found to be unsatisfactory as an exogenous carbon source. Endogenous carbon could not support high removal efficiencies. Freshwater columns adpated readily to an artificial seawater with a salinity of 18% without observable inhibition. Scanning electron microscopy revealed that the bacterial flora was mainly rod forms with the Peritricha (protozoa) dominating as the primary consumers. Denitrifying bacteria isolated from freshwater columns were tentatively identified as species of Pseudomonas and Alcaligenes. A pilot plant column was found to behave in a manner similar to the laboratory columns except that nitrite production was never observed. (+info)
Frequency of F116-mediated transduction of Pseudomonas aeruginosa in a freshwater environment.
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Transduction of Pseudomonas aeruginosa streptomycin resistance by a generalized transducing phage, F116, was shown to occur during a 10-day incubation in a flow-through environmental test chamber suspended in a freshwater reservoir. Mean F116 transduction frequencies ranged from 1.4 X 10(-5) to 8.3 X 10(-2) transductants per recipient during the in situ incubation. These transduction frequencies were comparable to transduction frequencies determined in preliminary laboratory transduction experiments. The results demonstrate the potential for naturally occurring transduction in aquatic environments and concurrent environmental and ecological ramifications. (+info)
The role of environmental antigens in the spontaneous development of autoimmunity in MRL-lpr mice.
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It has been proposed that the "normal" stimulation of the immune system that occurs from interactions with environmental stimuli, whether infectious or dietary, is necessary for the initiation and/or continuation of autoimmunity. We tested this hypothesis by deriving a group of MRL-lpr mice into a germfree (GF) environment. At 5 mo of age, no differences between GF and conventional MRL-lpr mice were noted in lymphoproliferation, flow cytometric analysis of lymph node cells (LN), or histologic analysis of the kidneys. Autoantibody levels were comparably elevated in both groups. A second experiment tested the role of residual environmental stimuli by contrasting GF mice fed either a low m.w., ultrafiltered Ag-free (GF-AF) diet or an autoclaved natural ingredient diet (GF-NI). At 4 mo of age, both groups showed extensive lymphoproliferation and aberrant T cell formation, although the GF-AF mice had approximately 50% smaller LNs compared with sex-matched GF-NI controls. Autoantibody formation was present in both groups. Histologic analysis of the kidneys revealed that GF-AF mice had much lower levels of nephritis, while immunofluorescence analysis demonstrated no difference in Ig deposits but did reveal a paucity of C3 deposition in the kidneys of GF-AF mice. These data do not support a role for infectious agents in the induction of lymphoproliferation and B cell autoimmunity in MRL-lpr mice. Furthermore, they suggest that autoantibodies do not originate from B cells that were initially committed to exogenous Ags. They do suggest a possible contributory role for dietary exposure in the extent of lymphoproliferation and development of nephritis in this strain. (+info)
Visual analogue scales for detecting changes in symptoms of the sick building syndrome in an intervention study.
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OBJECTIVES: This study tested questionnaires using visual analogue scales (VAS) in a cleaning intervention study and attempted to find a simple way of analyzing the replies to the questionnaires. METHODS: A VAS questionnaire made up of 26 questions was developed and marked once a week for 28 weeks by the room occupants in 3 buildings. A total of 1248 questionnaires was used in the analysis of the results. A simple model based on the differences between a person's average responses during 2 different periods was used in the analysis. RESULTS: No clear effect of the cleaning was found. Several significant correlations between different questions were established. Estimates for the design of future studies are given. CONCLUSIONS: The VAS questionnaire proved to be feasible for this type of study. It is suggested that each intervention period should last 4 weeks if the questionnaire is used once a week. However, the length of the period also depends on the expected latency of the symptoms, on how long it takes for environmental conditions to be affected by the intervention, and on how quickly conditions return to "normal" during control periods. (+info)
Infections in patients managed at home during autologous stem cell transplantation for lymphoma and multiple myeloma.
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A group of 51 patients with multiple myeloma, non-Hodgkin's lymphoma or Hodgkin's disease receiving high-dose chemotherapy and autologous peripheral blood stem cell rescue received chemotherapy and clinical care in the peritransplant period at home. This group was compared with 88 cases with the same diagnoses, receiving the peripheral stem cell transplant over the same time period as an inpatient in a high efficiency particulate air filtered bone marrow transplant unit. Patients were treated at home based on choice, geographic accessibility, availability of an educated care giver and a clean home environment, and comprehension of the concepts of infection and aseptic techniques. Febrile neutropenia and sepsis were not increased in the home group and no episodes of septic shock were seen in this group. Patients at home received prophylactic oral ciprofloxacin and roxithromycin during the phase when the absolute neutrophil count was < 1 x 10(9)/l. Fewer gram-negative infections, but no diminution in gram-positive infections or in the rate of fever were seen in patients at home. Empiric therapy with a third generation cephalosporin, teicoplanin and tobramycin was instituted in 31 patients who developed a fever greater than 38.5 degrees C. Of this group of 31, 18 required admission to hospital, 12 because of febrile neutropenia which persisted or was considered unsuitable for management at home due to sepsis. The remaining 13 with febrile neutropenia remained at home throughout, as did the 20 cases not developing neutropenic fever. This study demonstrates the feasibility of managing carefully selected patients in their home environment when at risk from febrile neutropenia or other septic complications following autologous peripheral stem cell support. (+info)
Experimental tests of predation and food hypotheses for population cycles of voles.
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Pronounced population cycles are characteristic of many herbivorous small mammals in northern latitudes. Although delayed density-dependent effects of predation and food shortage are often proposed as factors driving population cycles, firm evidence for causality is rare because sufficiently replicated, large-scale field experiments are lacking. We conducted two experiments on Microtus voles in four large predator-proof enclosures and four unfenced control areas in western Finland. Predator exclusion induced rapid population growth and increased the peak abundance of voles over 20-fold until the enclosed populations crashed during the second winter due to food shortage. Thereafter, voles introduced to enclosures which had suffered heavy grazing increased to higher densities than voles in previously ungrazed control areas which were exposed to predators. We concluded that predation inhibits an increase in vole populations until predation pressure declines, thus maintaining the low phase of the cycle, but also that population cycles in voles are not primarily driven by plant-herbivore interactions. (+info)