Diluent Water Research Articles

Exogenous Human Growth Hormone Reduces Body Fat in Obese Women

The effects of biosynthetic methionyl human growth hormone (met-hGH) on body composition and endogenous secretion of insulin-like growth factor I (IGF-I) were studied in obese women ranging between 138 and 226% of ideal body weight. Following double-blind procedures, 12 subjects were assigned at random to either treatment with met-hGH (n = 6, 0.08 mg/kg desirable body weight) or placebo (n = 6, bacteriostatic water diluent). Treatments were delivered intramuscularly three times per week for a period of 27-28 days. Subjects were instructed to follow a weight-maintaining diet and their pre- and posttreatment kilocaloric intake was monitored for verification. The baseline peak serum GH response to L-dopa/arginine stimulation for the study population as a whole, was in the hyposecretory range (9.6 +/- 1.9 ng/ml), accompanied by a low level of circulating IGF-I (0.56 +/- 0.09 U/ml). Hydrodensitometry revealed that the met-hGH-treated subjects had a significant reduction in body fat, while an observed mean increase in fat-free mass (FFM) approached significance. The percent change in body fat was unrelated to pretreatment levels of body fat, total body weight, or initial endogenous GH status. Changes in circulating IGF-I were similar to those for FFM, with increases approaching significance. There were no significant changes in body composition or IGF-I in the placebo-treated subjects. No significant differences were observed in the self-reported dietary intake of kilocalories during the experimental period between the two groups. We conclude that exogenous GH reduces body fat in obese women in the apparent absence of significant kilocaloric restriction. The effect appears to be unrelated to endogenous GH secretion or body composition.

A highly sensitive assay for adenosine triphosphate employing an improved firefly luciferase reagent

An improved firefly luciferase reagent allowed reliable detection of as little as 80 fmo1/1 adenosine triphosphate (ATP). Contamination by ATP of the deionized water diluent limited the sensitivity of the assay in some laboratories. The reagent can be used to measure ATP from less than ten bacterial cells if care is taken to eliminate ATP from equipment and reagents.

Influence of water activity and temperature on survival of and colony formation by heat-stressed Chrysosporium farinicola aleuriospores

The ability of sublethally heat-stressed aleuriospores of Chrysosporium farinicola to form colonies on yeast extract-glucose agar (YGA) supplemented with sufficient glucose, sorbitol, glycerol, and NaCl to achieve reduced water activity (aw) in the range of 0.88 to 0.95 was determined. The effects of the aw of diluent and incubation temperature during recovery and colony formation were also investigated. Aleuriospores harvested from 14-day-old cultures grown at 25 degrees C were less resistant to heat inactivation compared with aleuriospores from 20-day-cultures. Increased populations of heat-stressed aleuriospores were recovered as the aw of YGA was decreased from 0.95 (glucose and glycerol) and 0.94 (sorbitol) to 0.89 and 0.88, respectively. In NaCl-supplemented YGA, populations recovered at an aw of 0.94 were greatly reduced compared with populations detected at an aw of 0.92; no colonies were formed on NaCl-supplemented YGA at an aw of 0.88. Tolerance to aw values above 0.88 to 0.89 as influenced by solute type was in the order of glucose greater than sorbitol greater than glycerol greater than NaCl. Incubation at 20 degrees generally resulted in an increase in recoverable aleuriospores compared with incubation at 25 degrees C or at 30 degrees C for 14 days followed by 20 degrees C for 10 days. The lethal effect of NaCl on heat-stressed aleuriospores was enhanced at 30 degrees C. The retention of viability of aleuriospores held in sucrose-peptone water diluent (aw, 0.936) for 20 min was essentially the same as that observed when aleuriospores were held in peptone water (aw, 0.997).(ABSTRACT TRUNCATED AT 250 WORDS)

A Dilute Medium to Determine Population Size of Ammonium Oxidizers in Forest Soils

AbstractIncubation experiments using soils from mixed oak (Quercus sp.) stands showed accumulation of nitrate but standard most probable number (MPN) assays showed no NH4‐oxidizing bacteria were present. This led to a preliminary conclusion that nitrification in these soils must be heterotrophic. However, further incubation studies indicated that NH4‐N concentrations in standard MPN medium were too high for autotrophic NH4 oxidizers that are adapted to soils with low NH4‐N levels and exhibit low activities. Therefore, media with lower NH4‐N concentrations were tested against the standard MPN medium. Each medium was tested using both 1 mM phosphate buffer and deionized water as diluent to examine responses to small changes in buffer capacity. A 0.1 × medium used with deionized water diluent was found to best estimate populations of low‐activity NH4‐oxidizing bacteria present in soils with low NH4‐N concentrations.

Enteral Feeding Contamination: Comparison of Diluents and Feeding Bag Usage

This quasi-experimental study compared bacterial growth in enteral feeding solution in six Kangaroo feeding bags filled with enteral formula diluted with sterile water vs six of the same diluted with tap water. Feeding bags, which were on continuous pumps in patient-occupied rooms, were rinsed and refilled every 8 hours, and formula cultures were obtained at 0, 24, and 48 hr. Acceptability of cultures was based on published recommended standards. Low levels of nonpathogenic staphylococci were found in sterile water bags; high levels of bacilli and Gram negative rods were found in tap water bags. No significant differences were found in the relationship between type of formula diluent and outcomes. Type of water diluent and acceptability were not related. There was a systematic relationship between length of use and outcome; with both diluents, bags used over 24 hr became unacceptably contaminated. Further study with a larger sample is needed to determine the effects of using tap water rather than sterile water as diluent.

Acclimation‐induced changes in toxicity and induction of metallothionein‐like proteins in the fathead minnow following sublethal exposure to zinc

AbstractExperiments were conducted to determine if a correlation exists between acclimation‐induced alterations in Zn toxicity and the concentration of metallothionein‐like proteins (MTP) in a cyprinid fish. Populations of subadult fathead minnows,Pimephales promelas, were maintained in dechlorinated tap water and exposed to 0, 0.60 and 1.80 mg Zn/L for 35 d. Groups of animals (120 each) were removed from each acclimation population after 0, 7, 14, 21 and 35 d to conduct 96‐h acute tests. Tolerance and resistance were monitored as changes in the 96‐h LC50 and LT50 values, respectively. Tolerance increased a significant 28% above control values after 14 d of exposure to 0.60 mg Zn/L, but decreased significantly to 63 and 74% of control values following exposure to 1.80 mg Zn/L for 7 and 14 d (p< 0.05). Acute toxicity values returned to control levels in both treatment groups after 21 d of exposure and remained stable to 35 d. The concentration of MTP was measured in the viscera (i.e., liver, spleen, intestine and pancreas) indirectly as the total Zn‐binding capacity in MTP‐containing fractions. MTP levels increased after 7, 14 and 21 d and plateaued to 35 d. Metal concentration in the MTP fraction reached a maximum of 31.6 μg Zn/g viscera, and following 28 d of exposure to 1.80 mg Zn/L concentrations declined to control levels after 7 d in diluent water. Whole‐body residues of Zn reached steady state after 7 d of exposure to 0.60 mg Zn/L but continued to increase after 35 d of exposure to 1.80 mg Zn/L. Zn‐acclimated animals were cross‐resistant but not cross‐tolerant to acute Cd challenge. There was no correlation of alterations in toxicity with observed changes in MTP concentration. Growth effects were observed at both acclimation exposure levels.

Development of aquarium fish models for environmental carcinogenesis: an intermittent-flow exposure system for volatile, hydrophobic chemicals.

An intermittent-flow exposure system was designed to provide stable and manipulative concentrations of volatile and hydrophobic compounds to small aquatic animals for uninterrupted long periods. Test species for 28-day experiments included two aquarium fishes, the Japanese medaka (Oryzias latipes) and the king cobra guppy (Poecilia reticulata). Test chemicals included trichloroethylene, vinylidene chloride, bis(2-chloroethyl)ether, ethylene dichloride, and a mixture of carbon tetrachloride, trichloroethylene, chloroform, bromodichloromethane, chlorodibromomethane and bromoform. These compounds are drinking water biorefractories and are potentially carcinogenic. Concentrated aqueous toxicant solutions, delivered from a remote triple carboy dispensing system, were mixed with diluent water within an isolated chamber containing exposure aquaria and test fish. Toxicant concentrations measured throughout each exposure period proved to be stable within acceptable variability ranges as indicated by coefficients of variation generally less than 15%.

A flow-through extraction and dosage system for long-term bioassays with water-soluble oil hydrocarbons

Bioassays with oil hydrocarbons are often severely hampered by technical difficulties related to the physical and chemical properties of the oil. In this two-step flow-through system such difficulties are overcome by first producing a water-soluble fraction of the oil in a continuous extraction process. In the next step this stock solution is diluted with sea water in a set of proportional dilutors before it runs to the aquaria. During 10 weeks' continuous operation the total hydrocarbon concentration in the sea water extracted fraction was 1.9 ± 0.3 ppm ( n = 22). In the subsequent dilution step the fluctuations are still smaller, with coefficients of variation of typically 1–3%. Maintenance of the system is easy. There are fail-safe devices against pump break down, and overdosage is impossible since the toxicant addition is controlled by the diluent water flow.

A continuous-flow mini-diluter system for toxicity testing

A space saving portable mini-diluter exposure system for testing early life stages of fish and invertebrates has been developed and successfully used both in the laboratory and on-site with single chemicals and with complex effluents. This gravity-operated system can also be installed in a compact, vented enclosure to permit safe testing of hazardous volatile chemicals. The mini-diluter test system has several additional advantages over other widely used dosing systems in that it: (1) uses small volumes of complex effluents and/or single chemicals which reduces the problem of removing hazardous material from the test system's waste water; (2) works well with waste containing suspended solids; and (3) can maintain normal operation for up to 10 h if the effluent headbox supply pump fails and up to 4 h if the diluent water headbox supply pump fails.

The effect of metronidazole on the human taste threshold to alcohol.

SummaryA method is described for measuring the taste threshold to alcohol in a sample of 163 subjects whose average age was 27 years. The subjects taste ascending concentrations of alcohol in water from 0.25% up to 64% absolute alcohol. Five mls of each concentration is tasted for 20 seconds, spat out, and then the subject washes out his mouth with the diluent water. Alcohol is detected as a sweet taste at a concentration of 4.2±S.E. 0.24% alcohol. The sweet taste changes to a burning taste at a mean concentration of 21.2±S.E. 1.22% alcohol. The frequency distributions for the sweet and burning tastes of alcohol depart significantly from the unimodal normal shape. During the 20 seconds while alcohol is maintained in the mouth for appreciation of its taste, the concentration of the 4% solution falls to 2%, and the concentration of the 20% solution falls to 16%. The taste threshold for metronidazole was tested in the same subjects and found to be 149±S.E. 17 mg/litre; the frequency distribution curve is unimodal in shape but negatively skewed. The taste threshold for PTC in the same subjects was bimodal with modes at 20 and 1300 mg/litre.Oral administration of 600 mg of metronidazole as 200 mg tablets over a period of 14 hours, caused no change in the taste threshold to alcohol during the following 6 days. Administration of 800 mg metronidazole over a period of 20 hours, caused a significant elevation of both sweet and burning taste thresholds to alcohol which reached its maximum on the second day after the last tablet had been taken. The taste threshold returned to its pre‐metronidazole level on the fourth day. The alcohol taste threshold was raised at concentrations of metronidazole equivalent to those excreted in the saliva.The taste threshold to alcohol is a measurable human physiological characteristic. In humans, and by implication in rats, taste threshold to alcohol is appreciated through pereipheral receptors and specific afferent taste discharges, and the taste mechanism is the primary regulator of alcohol intake. The finding of a taste threshold distribution curve with more than one mode provides evidence that there may be a genetic basis to variations in alcohol taste threshold. The action of metronidazole on the alcohol taste threshold suggests that this drug may exert psychotherapeutic effects on alcohol consumption in man not only through peripheral taste receptiors but also through central taste pathways.

Development of Methodology and Apparatus for the Bioassay of Oil

ABSTRACT Bioassay of petroleum or its components presents technical problems not encountered in testing of soluble and less volatile materials. The literature includes numerous accounts of toxicity for both crude and refined oil. In most instances, the indices of toxicity are based on metered inflow. Few such studies, however, consider the concentrations of oil in the water column to which the test organism is exposed. Essentially oil and water form a two-phase system. Even on a continuous flow basis, oil cannot be maintained as a homogeneous oil-water mixture within a bioassay test system. Homogenization techniques produce a totally artificial environment dissimilar to natural conditions characterized by a slick of floating oil. Furthermore, since subsurface oil concentrations may represent a small fraction of the metered inflow, currently applied indices of toxicity based on metered inflow may be erroneous. This presentation summarizes techniques that may be applied in the bioassay of oil and other non-miscible materials. Special attention is directed to the above problems. Bioassay procedures are described that are conducted in flow-through tanks equipped with gravity oil metering systems and static mixers to equilibrate diluent water. Oil concentrations measured at different depths are utilized to calculate the mean level of exposure of the test organisms in the water column. Habitat preference and behavior of the test organism during bioassay were assessed in relationship to toxicity. This work was performed under contract to the American Petroleum Institute, Committee on Environmental Affairs.

Modified Littman oxgall agar to isolate Cryptococcus neoformans.

Littman Oxgall Agar was modified by adding an extract of Guizotia abyssinica seeds with a water diluent for rehydration. In this medium, colonies of Cryptococcus neoformans became brown, but the color failed to develop in eight other yeasts and yeast phases of diphasic organisms. The depression of saprophytic fungi noted on Littman Oxgall Agar was not lost in the modification.

Modified Littman Oxgall Agar to Isolate Cryptococcus neoformans1

Littman Oxgall Agar was modified by adding an extract of Guizotia abyssinica seeds with a water diluent for rehydration. In this medium, colonies of Cryptococcus neoformans became brown, but the color failed to develop in eight other yeasts and yeast phases of diphasic organisms. The depression of saprophytic fungi noted on Littman Oxgall Agar was not lost in the modification.

Cyanmethaemoglybinometry on the auto analyzer.

In this department, haemoglobinometry has been routinely carried out for more than six years on an AutoAnalyzer. The original oxyhaemoglobin method was described in this journal (Nelson and Lamont, 1961). The possibility of adapting this analytical technique to the estimation of haemoglobin by the more stable cyanmethaemoglobin method was tested by us and reported to be satisfactory at the Symposium on AutoAnalyzer Techniques which was held in London in 1962. The recent article on cyanmethaemoglobinometry on the AutoAnalyzer by Kemp (1966) has prompted us to put on record the modifications which we introduced to convert our original system to the determination of haemoglobin by the cyanmethaemoglobin method. These changes have consisted of (1) the replacement of the ammonia water diluent by a Drabkin ferricyanidecyanide reagent1; (2) the introduction ofa wash between the individual blood specimens, using the Pecker2 auto-

Synergism in the solvent extraction of di-, tri- and tetravalent metal ions—II: Synergic effects in so-called inert diluents

Greatly enhanced extractions (synergism) for di, tri and tetravalent metals have been reported for the system M n+ /HTTA/S/diluent where HTTA is thenoyltrifluoracetone and S varies from the highly polar tri-octyl phosphine oxide to the weakly basic triphenyl phosphate. The extracted species M(TTA) n S x is the same, whatever “inert” diluent is used, but the partition coefficients of the metal ion vary over several powers of ten, sometimes by a factor much greater than that obtained by the synergic effect itself. The effect, on the extraction, of so-called “inert” diluents such as cyclohexane, hexane, carbon tetrachloride, benzene and chloroform has been studied under various conditions. In all cases the distribution ratio decreases as the diluent is changed from cyclohexane in the above sequence, chloroform giving the lowest partition coefficient. This order is in the same sequence as the water solubility in the pure diluent and the diluent effect on metal extraction is probably connected through the diluent water content with the permanent or induced diluent dipole.

Biochemical and biological evidence of the activity of high potencies

Summary1. A method is described for investigating the possible action of microdoses of mercuric chloride on the hydrolysis of soluble starch with malt diastase.2. The microdoses of the mercuric chloride used in the latest crucial series carried out in1946, 1948, and 1952, were what are termed “high potencies” made in accordance with the pharmaceutical method of preparation of drugs ordinarily used in the practice of homœotherapy.3. These microdoses were prepared by separate stages of dilution, the solution at each stage being subjected to mechanical shock. The solutions were, theoretically, “dilutions” of the order of 1 in 10−61 and on present physical theory would not contain any molecules of the original mercuric chloride.4. The difference in rate of hydrolysis between flasks containing starch, diastase, and distilledwater (controls) and flasks containing starch, diastase and microdoses of mercuric chloride (tests) were compared colorimetrically by the Spekker absorptiometer, and the frequencies of the differences statistically analysed, as the results obtained showed biological scatter. More than 500 such comparisons were carried out. The differences of means were examined by the Fisher “t” test, the variances tested and Cochrane and Cox's test applied where indicated. All the series gave a highly significant difference in the rate of hydrolysis between controls and tests, the microdoses stimulating the process. Statistically the significance is shown by the fact that a probability of <0·001 was obtained independently in each of the three years 1946, 1948 and 1952. The control results gave an approximately normal distribution.5. The distribution, control methods, and accessory control procedures were considered toexclude, as a cause of the effects, adsorption of the original drug and the presence of extraneous contaminants by chance solely in test flasks. The only difference between control and microdose flasks was the addition of microdose, the distilled water being common to both controls and tests.6. It was concluded that a factor, unidentified, derived from the mercuric chloride used, waspresent in solutions prepared by serial dilution with mechanical shock which could affect the distilled water diluent, that this change was transferable to subsequent “ultramolecular” stages of “dilution”, and that this factor was the source of the activity in the microdose solutions producing the acceleration of the rate of hydrolysis.7. In an addendum there is described recent biological work which is also providing evidence of the presence of an active selective factor in “high potencies” derived from Strophanthus sarmentosus by the same methods of dilution with mechanical shock.