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PubMed1986

Correction of urinary mercury concentration by specific gravity, osmolality, and creatinine.

Corrections for specific gravity, osmolality, and creatinine were applied to identical urinary mercury data in order to investigate the reproducibility of the corrected mercury concentration in a person's urinary spot samples throughout a 24-hour period; and the extent to which it is possible to predict a person's 24-hour mercury excretion from the corrected mercury concentration in the corresponding spot samples. The data indicate that on the average these corrections improve reproducibility by a factor of approximately 2. In individual cases, the uncorrected and corrected values of mercury concentration can differ by as much as a factor of 6. Similar effects were observed in the correlation of the mercury concentration of a spot sample and the corresponding 24-hour excretion of mercury. For this set of data, the corrections for specific gravity and osmolality turned out to be almost identical. The correction for creatinine was more effective than the other corrections by a small but statistically significant amount.

Body Weight↗

PubMed1997

Estimation of the composition of broiler carcasses from their specific gravity.

An experiment was conducted to quantify the relationships between broiler carcass specific gravity and chemical composition (percentage moisture, percentage lipid, percentage protein). Carcasses of widely varying compositions were produced by feeding several dietary protein and energy combinations (52 to 64% moisture, 0.6 to 2.5% ash, 1.6 to 11.7% lipid, and 4.9 to 8.0% nitrogen). Very strong relationships were found between percentage moisture and percentage lipid (r = -0.969) and percentage moisture and percentage N (r = 0.968). Strong relationships were found between specific gravity and percentage lipid (r = -0.872) and specific gravity and percentage N (r = 0.857). Specific gravity is recommended as a means to estimate carcass fat in broiler chickens.

Animals↗

PubMed1998

Effect of low urine specific gravity on pregnancy testing.

Urine pregnancy tests performed at a large urban university student health center were examined for specific gravity to determine whether a low urine specific gravity, compared with a serum specimen, could alter the result of a urine pregnancy test. At the same time, a serum pregnancy test was performed on those samples with negative results and a specific gravity of less than 1.015. During the study period, 410 urine specimens were evaluated. Eighty of the women with a specific gravity under 1.015 had negative urine pregnancy tests with a concomitant serum specimen. The authors concluded that current sensitive immunoassay tests for human chorionic gonadotropin (HCG) are highly sensitive and that low specific gravity does not appear to alter this sensitivity.

Bias↗

PubMed1991

Measurement of brain tissue specific gravity using pycnometry.

In this paper we introduce and characterize pycnometry, a method used to measure fluid density, for determining a tissue's specific gravity. It uses a 2-ml glass pycnometer filled with distilled water to determine a tissue sample's displacement volume. The tissue's density is determined when it's weight is divided by this volume and specific gravity is computed by dividing the tissue density by the density of water. Pycnometry was validated using pre-calibrated glass, specific gravity standards over the range 1.03-1.26, and compared to the density gradient method using rat brain tissue. We observed that the specific gravity values obtained using pycnometry were highly correlated with the specific gravity standards (slope = 1.0107, r = 0.996) and with the density gradient column when tissue volumes larger than 0.120 ml were used with the pycnometer (slope = 1.0707, r = 0.9826). Good correlation was also observed between percent water content values computed using the Nelson equation with pycnometry or density gradient specific gravity values versus the measured percent water content values obtained with the wet weight/dry weight method. Pycnometry is an accurate, reproducible technique to measure tissue specific gravity and brain edema and is best suited for use in a laboratory that engages sporadically in brain edema measurement.

Animals↗

PubMed1992

Specific gravity of bovine colostrum immunoglobulins as affected by temperature and colostrum components.

The effects of temperature and colostrum components on specific gravity in bovine colostrum were investigated. Thirty-nine first milking colostrum samples were collected from Holstein cows. The samples were assayed for alpha-tocopherol, fat, protein, total solids, and IgG. The concentrations of total solids, total protein, total IgG, and fat in colostrum were 26.6, 12.5, 3.7, and 9.4 g/100 g, respectively. A range of 1.8 to 24.7 micrograms/ml for alpha-tocopherol was measured in the colostrum samples. Specific gravity of the colostrum was measured using a hydrometer in increments of 5 degrees C from 0 to 40 degrees C. Specific gravity explained 76% of the variation in colostral total IgG at a colostrum temperature of 20 degrees C. The regression model was improved only slightly with the addition of protein, fat, and total solids. The model for samples at 20 degrees C was IgG (milligrams per milliliter) = 958 x (specific gravity) - 969. Measurement of specific gravity at variable temperatures necessitated inclusion of temperature in the model for estimation of IgG. Inclusion of the other components of colostrum into the model slightly improved the fit. The regression model for samples at variable temperatures was as follows: IgG (milligrams per milliliter) = 853 x (specific gravity) + .4 x temperature (Celsius degrees) - 866.

Animals↗

PubMed1994

Immunoglobulin concentration, specific gravity, and nitrogen fractions of colostrum from Jersey cattle.

Colostrum samples from 88 Jersey cows were analyzed for concentrations of IgG, IgM, IgA, total solids, specific gravity, and N fractions. Colostrum (50 ml) was sampled from each cow as soon as possible after parturition, and specific gravity was determined immediately using a hydrometer. Samples then were frozen prior to analysis of Ig, fat, and N fractions. Mean concentrations of IgG, IgM, and IgA were 65.8, 2.4, and 1.7 g/L, respectively. Concentration of IgG was lower, and IgA was higher, in colostrum from second lactation cows than from first lactation cows or from cows in third or later lactations; IgM increased linearly as lactation number increased. Total N, protein N, noncasein N, and fat contents also were lower in second lactation cows. Regression of total Ig (grams per liter) on specific gravity was -1172 + 1180 x specific gravity (r2 = .38). Relationship of total Ig to specific gravity differed from colostrum of Holstein cattle and may have been related to differences in fat and noncasein N concentrations. Use of specific gravity hydrometer to estimate Ig concentration using equations derived from Holstein cattle appears to underestimate Ig concentration in colostrum from Jersey cattle.

Animals↗

PubMed1998

Improving the specific gravity adjustment method for assessing urinary concentrations of toxic substances.

Changes in urinary flow induce changes in urinary concentrations of toxic substances. The authors modified the conventional specific gravity adjustment method for measuring urinary concentration of toxic substances to compensate for the dilution effects from varying degrees of hydration. The conventional specific gravity adjustment method is a special case to the more general method proposed in this article. The conventional method generally does not correct the urinary concentration to the mean specific gravity of urine. It requires the assumption that a change in urine flow preserves the relative ratio between the mass of the xenobiotic and the mass of total dissolved solids. The derivation of the modified specific gravity adjustment method shows that a change in urine flow does not necessarily preserve this ratio. An experimental slope between urinary flow and urinary specific gravity was linear on a log scale. A ratio was formed between the experimental slope and Araki's "b" slopes for various substances to predict changes in urine concentrations due to changes in the specific gravity of a spot sample. Since excretion rates typically vary for different substances with changes in urinary flow, an appropriately weighted exponential adjustment factor is required for each substance to normalize its concentration to the standard specific gravity of urine.

Adult↗

PubMed1989

Modelling the relationships of egg weight, specific gravity, shell calcium and shell thickness.

1. The relationships between egg weight, egg specific gravity, shell weight, shell calcium and shell thickness of 800 eggs from 8 treatments were expressed using mathematical models. 2. The equations describing the relationships were on the basis of any two independent variables predicting the remainder. 3. Of 10 possible models, 4 had high co-efficients of determination (R2 greater than 0.80) for each predicted dependent variable. 4. The two independent variables in each of these 4 models were, in turn, egg weight and specific gravity, egg weight and shell weight, egg weight and shell thickness, and specific gravity and shell weight. 5. The best model was that having egg weight and specific gravity as independent variables, with R2 values of 0.94, 0.88, and 0.85 for predicted shell weight, shell calcium, and shell thickness, respectively. Moreover, egg characteristics can be measured non-destructively by this model, whereas the other three require destruction of the egg.

Age Factors↗

PubMed1986

Passage of inert particles varying in length and specific gravity through the postruminal digestive tract of steers.

Postruminal passage of inert particles varying in specific gravity, length, and time of administration in relation to feeding, as well as interactions among these factors, were studied in four ruminally cannulated steers. Animals were allowed access to a 40% grain mix, 60% long alfalfa hay diet for 6 h daily. Eleven combinations of particle specific gravity (.9, 1.17, 1.41, or 1.77) and length (1, 5, or 10 mm) were used. Two hundred particles of each combination were placed in the abomasum at the beginning of the meal, the end of the meal, or 6 or 12 h after the end of the meal. Recovery of particles in feces within 24 or 48 h of administration and times of first appearance and maximal concentration were examined. Particle recovery 24 h after dosing as a percentage of 48-h recovery and time of maximal concentration in feces best described postruminal passage of inert particles. Passage was affected by specific gravity, but not length, of particles. Those having a specific gravity of 1.17 passed most quickly. Time at which particles were placed in the abomasum in relation to feeding affected the passage of particles varying in specific gravity. This interaction may be important in studies of ruminal passage that depend on marker appearance in feces.

Animals↗

PubMed2006

The effect of seasonal changes on blood pressure and urine specific gravity in children living in Mediterranean climate.

BACKGROUND: We aimed to evaluate the effects of seasonal changes on urinary specific gravity, blood pressure and urinary erythrocyte number in children living in Mediterranean climate. MATERIAL/METHODS: The study was conducted on 547 children who presented for routine follow up to healthy-child care department between January 1997 and December 2002. Age, sex, weight, height, blood pressure, urinary specific gravity and urinary erythrocyte number were recorded by retrospective evaluation of files. Then, the parameters during summer were compared with those during winter. Additionally, correlation between the blood pressure, urinary specific gravity and urinary erythrocyte number was assessed separately during summer and winter. RESULTS: Anthropometrical measurements and mean age of the patients in summer and winter groups were similar. There was no significant change in urinary specific gravity (p > 0,05), while systolic and diastolic blood pressures were significantly higher in winter (p = 0.031 and p = 0.028 respectively). Temperature and humidity levels did not change significantly among different years but mean air temperatures during summer positively correlated with time from 1997 till 2002 (r = 0.965, p = 0.002). Blood pressure and urinary specific gravity were not correlated to each other at any time. Contrarily, there was a positive correlation between urinary specific gravity and erythrocyte number in summer (p = 0.01). The number of children with hematuria and degree of hematuria did not differ significantly between summer and winter. CONCLUSIONS: Seasonal changes in Mediterranean climate do not lead to changes in hydration status or in urinary erythrocyte number in children. Therefore, the decrease in blood pressure during summer can not be attributed to the hydration status.

Adolescent↗

PubMed1992

Identification of specific gravity sensitive signal transduction pathways in human A431 carcinoma cells.

Epidermal growth factor (EGF) activates a well characterized signal transduction cascade in human A431 epidermoid carcinoma cells. The influence of gravity on EGF-induced EGF-receptor clustering and early gene expression as well as on actin polymerization and actin organization have been investigated. Different signalling pathways induced by the agents TPA, forskolin and A23187 that activate gene expression were tested for sensitivity to gravity. EGF-induced c-fos and c-jun expression were decreased in microgravity. However, constitutive beta-2 microglobulin expression remained unaltered. Under simulated weightlessness conditions EGF- and TPA-induced c-fos expression was decreased, while forskolin- and A23187-induced c-fos expression was independent of the gravity conditions. These results suggest that gravity affects specific signalling pathways. Preliminary results indicate the EGF-induced EGF-receptor clustering remained unaltered irrespective of the gravity conditions. Furthermore, the relative filamentous actin content of steady state A431 cells was enhanced under microgravity conditions and actin filament organization was altered. Under simulated weightlessness actin filament organization in steady state cells as well as in EGF-treated cells was altered as compared to the 1 G reference experiment. Interestingly the microtubule and keratin organization in untreated cells showed no difference with the normal gravity samples. This indicates that gravity may affect specific components of the signal transduction circuitry.

Calcimycin↗

PubMed1979

Falsely high refractometric readings for the specific gravity of pleural fluid.

For 128 pleural fluids, the relationship between the protein content and the reading for the specific gravity obtained from a refractometer calibrated for urinary specific gravity was analyzed. The refractometer gave falsely high levels for the specific gravity of the pleural fluid. A reading for 1.019 (rather than 1.016) corresponded to a concentration of protein of 3.0 gm/100 ml, and each deviation of 0.005 (rather than 0.003) coresponded to a concentration of 1 gm/100 ml; however, determinations of the concentration of protein in the pleural fluid directly from the refractometer's scale for protein (calibrated for serum) was rapid and accurate. Calculation of the protein content of the pleural fluid from the reading for specific gravity on the refractometer is erroneous and sometimes misleading.

False Positive Reactions↗

PubMed2005

A quantitative computed tomography assessment of brain weight, volume, and specific gravity in severe head trauma.

BACKGROUND: Computed tomography DICOM images analysis allows a quantitative measurement of organ weight, volume and specific gravity in humans. METHODS: The brain weight, volume and specific gravity of 15 traumatic brain-injury patients (3+/-2 days after trauma) were computed using a specially designed software (BrainView). Data were compared with those obtained from 15 healthy subjects paired for age and overall intracranial volume. RESULTS: Hemisphere weight were 91 g higher in patients than in controls (1167+/-101 vs 1076+/-112 g; p<0.05). Specific gravity of hemispheres (1.0367+/-0.0017 vs 1.0335+/-0.0012 g/ml; p<0.001), brainstem (1.0302+/-0.0016 vs 1.0277+/-0.0015 g/ml; p<0.001) and cerebellum (1.0396+/-0.0020 vs 1.0375+/-0.0015 g/ml; p<0.05) was significantly higher in traumatic brain injury (TBI) patients than in controls (all p<0.0001 without interaction). This increase in specific gravity was evenly distributed between the hemispheres, the brainstem and the cerebellum, and the grey and white matter. It was more pronounced in the rostral than in the caudal areas of the hemispheres. It was independent of the volume of brain contusion, of the mechanism of head injury, of natremia and of initial Glasgow coma score. CONCLUSION: Human TBI patients present a diffuse increase in specific gravity. This observation is in sharp opposition with the data derived from the experimental literature.

Adolescent↗

PubMed1981

[Relationship between the refractive index and specific gravity of the rat urine (author's transl)].

The relationship between the refractive index and specific gravity of urine was studied with specimens from 165 Sprague-Dawley rats, by graphic analysis of the plot of the refractometrically determined index against the specific gravity which was measured with a pycnometer. 1. A linear regression was demonstrated between the refractive index and specific gravity. 2. The nomogram fitted the data of even those samples with high refractive index and specific gravity, irrespective of changes in food or water intake and protein or glucose contents in the urine. 3. The nomogram was in good agreement, in respect of linearity, with the regression line derived from the conversion table of TS meter by the American Optical Corporation and also with the nomogram of the Japanese Society of Clinical Pathology. It approximated more closely to the former than to the latter.

Animals↗

PubMed1986

Relationships among serum immunoglobulin concentration in foals, colostral specific gravity, and colostral immunoglobulin concentration.

Postpartum, presuckle, colostrum samples were collected from 100 mares. Colostral specific gravities significantly correlated (r = 0.9) with colostral immunoglobulin (Ig)G concentrations. Foal serum IgG concentrations highly correlated (r = 0.82) with specific gravities of the colostrum each foal ingested. Eight of 48 foals (17%) had serum IgG concentrations less than 400 mg/dl. The dams of these 8 foals had colostral sp gr less than 1.06 and colostral IgG concentrations less than 3,000 mg/dl. Foals had serum IgG concentrations greater than 520 mg/dl 24 hours after parturition, when the colostral specific gravity of the dam was greater than or equal to 1.06. Effects of breed on colostral specific gravity, colostral IgG concentrations, foal serum IgG concentrations, and mare serum IgG concentrations were not significant.

Animals↗

PubMed1991

The urine specific gravity dipstick: a useful tool to increase fluid intake in stone forming patients.

High fluid intake is the only preventive dietary measure that can be recommended to all patients with stones. However, the efficacy of dietary advice given to patients is unknown. We compared the impact of dietary advice to increase hydration (group 1, 57 patients) and of no dietary advice (group 2, 83 patients) on 24-hour urine volume. No significant difference was noted between groups 1 (1,624 ml.) and 2 (1,732 ml.). We then determined if urine specific gravity dipsticks could help patients increase the 24-hour urine volume. A correlation between 24-hour urine volume and mean urine specific gravity was performed on 263 randomly chosen patients. There was an inverse relationship between urine specific gravity and 24-hour urine volume with a correlation coefficient of 0.522 (y = 1.0207 - 0.00374x). Most patients (81.6%) with 24-hour urine volumes of less than 2.1 had a urine specific gravity of more than 1.010. The use of specific gravity dipsticks was evaluated as a tool to help 24 patients increase the 24-hour urine volume. The 24-hour urine volume increased significantly (p less than 0.05, paired Student's t test) in patients after feedback from specific gravity dipsticks when they were instructed to keep the urine specific gravity at or less than 1.010 (average 24-hour urine volume increased 192%). We conclude that dietary advice may be insufficient to modify fluid intake habits in stone patients. However, modifications of fluid intake habits may be improved by feedback from specific gravity dipsticks.

Adolescent↗

PubMed1988

Specific gravity test strips used in monitoring urine concentrations of urolithiasis patients.

Current therapy for urolithiasis patients includes instructions to increase water intake and 24-hour urine output. Previous studies have measured changes in the 24-hour urine volume to evaluate the efficacy of fluid therapy in each patient. We used paper test strips to monitor urine pH and specific gravity in 22 of our stone clinic patients: 10 were instructed to increase water intake just before the study (group 1) and 12 were not so instructed (group 2). Mean specific gravities of 1.0222 (1.0238 corrected for pH) for group 1 and 1.0197 (1.0220 corrected for pH) for group 2 did not differ significantly. Urine specific gravities also were compared for 3 intervals: 1 to 9 a.m., 9 a.m. to 5 p.m. and 5 p.m. to 1 a.m. Of the 22 patients 10 (3 from group 1 and 7 from group 2) had significant diurnal variations in the urine specific gravities, corrected and uncorrected, among these 3 periods. In addition, both groups had a significantly higher mean specific gravity from 1 to 9 a.m. (1.0234 uncorrected and 1.0248 corrected) than from 9 a.m. to 5 p.m. (1.0194 uncorrected and 1.0218 corrected). The 5 p.m. to 1 a.m. (mean of 1.0220 uncorrected and 1.0239 corrected) specific gravity did not differ significantly in either group. If 1.015 is the highest acceptable specific gravity of urine in stone patients, the findings suggest inadequate dilution of urine in these patients, whether or not they were instructed to increase water intake. Also, the significant diurnal variation in urine specific gravity would allow a nighttime triggering event at these hours of higher urine concentration.

Adult↗

PubMed1984

[Adjustment of urinary delta-aminolevulinic acid concentrations in workers exposed to lead and heat. Adjustments of specific gravity to 1.020 and urinary volume coefficients].

Adjustments of urinary ALA concentrations as to urinary specific gravity and creatinine were examined for workers exposed to lead and heat. Judging from our findings, we suggested that it was preferable to adopt the specific gravity (UG) at 1.020 as the adjustment value to obtain the correct urinary ALA concentration. Though corrected values thus obtained were found adequate for urine in the normal range of specific gravity, they failed to be adequate for concentrated urine samples higher than UG 1.025. Urinary volume adjustment was found to be necessary for these concentrated urine in stead of urinary specific gravity adjustment. For the practical purposes, we postulated urinary volume coefficients, which were estimated to be 0.5 for samples ranging from UG 1.026 to 1.030, 0.4 for samples from UG 1.031 to 1.035 and 0.3 for samples from UG 1.036 to 1.040, respectively.

Aminolevulinic Acid↗