PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “SPECIFIC GRAVITY”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Screening for microalbuminuria simplified by urine specific gravity.

BACKGROUND: The albumin-to-creatinine ratio and the 24-hour urine collection to measure microalbuminuria are inconvenient and expensive. The newer rapid and less expensive dipstick methods for screening of microalbuminuria estimate only albumin and are subject to errors caused by variation in volume. We determined the relation between urine-specific gravity (Usg) and urine creatinine (Ucr) so that Ucr can be derived from Usg to correct for albumin concentration in the urine which is influenced by urine volume. METHODS: We randomly included 42 consecutive patients from the primary care clinic, and 34 patients from the diabetic clinic. RESULTS: We found that a very good correlation existed between Usg and Ucr in the 42 patients from the primary care clinic (Ucr = 11.4 x Usg -11,509, r = 0.83, p < 0.001). Patients from the diabetic clinic who had well-controlled blood sugar (n = 21) showed a similar trend (Ucr = 10.82 x Usg -10,882, r = 0.87, p < 0.001). However, this was not the case with uncontrolled diabetics (Ucr = 2.53 x Usg -2,513, r = 0.26, NS). Using simple arithmetic, we derived a simplified formula where Ucr can be predicted from Usg. Using multiple regression to incorporate the urinary glucose level by dipstick, a more generic formula was obtained for estimating urinary creatinine. CONCLUSION: Usg can be used instead of Ucr to normalize for the varied urine concentration while screening for microalbuminuria. Poorly controlled diabetics should be screened after their blood sugars are well controlled or use the more generic formula that incorporates urinary glucose. Thus, by measuring spot urine albumin and specific gravity by dipsticks one gets an easy, immediate and accurate estimation of microalbuminuria in an office setting.

Albuminuria↗
PubMed1991

Specific gravity of eggs and eggshell weight from commercial layers and broiler breeders in relation to time of oviposition.

Eggs were collected from 1 day of production of Hy-Line W36 commercial egg production hens 55 wk old. Also, eggs were collected from 1 day of production of Arbor Acres broiler breeder hens when they were 40 and 55 wk of age. The eggs were immediately weighed (EW) after collection and specific gravity (ESG) determined. The eggs were then broken and the contents removed. Shells were washed, air dried, and weighed. The weights of shells (ESW) were calculated using the following formulas: Broiler breeder ESW = 1.9128 x EW - 1.9741 EW/ESG and layer ESW = 1.9140 EW - 1.9754 EW/ESG. Shell density (ESD) was calculated using a modification of this formula. Egg weights of both commercial layers and broiler breeders were heaviest in the early morning. There was a steady decline in EW until 1545 h; EW increased thereafter. Specific gravity of eggs was highest in the morning, declined until 1245 h, and then increased thereafter. Shell weight was also highest in the morning, declined until 1245 h, and then increased thereafter. The calculated and measured ESW were highly correlated. The ESD was 2.147 and 2.160 for the commercial layers and broiler breeders, respectively.

Animals↗
PubMed2001

Dipstick measurements of urine specific gravity are unreliable.

AIM: To evaluate the reliability of dipstick measurements of urine specific gravity (U-SG). METHODS: Fresh urine specimens were tested for urine pH and osmolality (U-pH, U-Osm) by a pH meter and an osmometer, and for U-SG by three different methods (refractometry, automatic readout of a dipstick (Clinitek-50), and (visual) change of colour of the dipstick). RESULTS: The correlations between the visual U-SG dipstick measurements and U-SG determined by a refractometer and the comparison of Clinitek((R))-50 dipstick U-SG measurements with U-Osm were less than optimal, showing very wide scatter of values. Only the U-SG refractometer values and U-Osm had a good linear correlation. The tested dipstick was unreliable for the bedside determination of U-SG, even after correction for U-pH, as recommended by the manufacturer. CONCLUSIONS: Among the bedside determinations, only refractometry gives reliable U-SG results. Dipstick U-SG measurements should be abandoned.

Humans↗
PubMed1999

A global hypoxia preconditioning model: neuroprotection against seizure-induced specific gravity changes (edema) and brain damage in rats.

Hypoxia preconditioning states that a sublethal hypoxia episode will afford neuroprotection against a second challenge in the near future. We describe and discuss a procedure for the development of global hypoxia preconditioning in adult male Wistar rats, using a mildly hypoxic (9% O(2), 91% N(2)) atmospheric exposure of 8 h. The persistence of neuroprotection was analyzed using a kainic acid (KA) model of brain injury. Rats were challenged with KA (14 mg/kg, i.p.) on 1-14 days post-hypoxia. The effects of hypoxia preconditioning on seizure score, weight loss, brain edema and histopathology were assessed. Brain edema, predominantly of vasogenic origin, was measured 24 h after KA administration using a reproducible and quantitative method based on the specific gravities of tissue samples. A density gradient column (1.0250-1.0650 g/cm(3)) comprised of kerosene and bromobenzene was used to assess the presence of edema in regions involved in seizure initiation and propagation that are normally extensively damaged (i.e., piriform cortex and hippocampus). Specific gravities of tissues were calculated through extrapolation with known NaCl standards. We found that hypoxia preconditioning prevented the formation of edema in these brain regions when KA challenge was given 1, 3, and 7, but not 14 days post-hypoxia exposure. Furthermore, neuroprotection was observed in animals that had robust seizures. The described procedure may be used to examine the neuroprotective mechanisms induced by global hypoxia preconditioning against many subsequent challenges reflecting a variety of experimental models of brain injury, and will provide a better understanding of the brain response to hypoxia and stress.

Animals↗
PubMed1990

Intraocular tolerance to silicone oils of different specific gravities. An experimental study.

Different methylphenylsilicone (MPS) and fluorosilicone (FS) oils having a higher specific gravity than water were investigated as vitreous replacements. Their intraocular tolerance in vitrectomized aphakic rabbit eyes was evaluated for periods of up to 4 months and compared to that of regular polydimethylsilicone oil (PDMS). Weakly fluorinated FS and weakly phenylated MPS showed a presumably toxic effect on the retina. As compared to highly fluorinated FS, highly phenylated MPS showed better intraocular tolerance; however, inflammatory reaction was slightly more extensive than in eyes filled with PDMS.

Animals↗
PubMed1987

Silicone oil with high specific gravity for intraocular use.

Silicone oil with a higher specific gravity than that of intraocular fluid or polydimethylsiloxane may have special indications in vitreoretinal surgery. Trifluorsiloxane is such a substance, and therefore its biological compatibility was investigated in rabbit eyes. It was found that this substance was clinically well tolerated within the observation time of up to 6 months, even if there was some neovascularisation from the inferior limbus. Histologically both an inflammatory response and tissue impregnation were more pronounced than with normal polydimethylsiloxane.

Animals↗
PubMed1993

[Urinary specific gravity--comparative measurements using reagent strips and refractometer in 340 morning urine samples].

The specific gravity of urine (SG) indicates the number and weight of solute particles in urine; its measurement is helpful in interpreting proteinuria detected by dipstick tests and in monitoring adequate hydration in patients with nephrolithiasis. Four methods for measuring SG or osmolality of urine are currently available (depression of the freezing-point, urometry, refractometry, cation exchange on a reagent strip). Using a recently developed reagent strip, we have measured SG in morning urines of 340 non-selected outpatients and compared the results with SG measurements by refractometry of the same urines. In 86.2% of all urines, a good positive correlation between SG measured by reagent strip and refractometry was noted (r = 0.913, p = 0.0001). In 13.8% of the urines, however, the SG measured by reagent strip deviated by more than +/- 5 from the value obtained by refractometry; in 90% of these urines, glucosuria (reagent strip values too low or too high), proteinuria (values too high), or bacteriuria/leukocyturia (values too low or too high) could be found. In alkaline urine (pH > 7.0), SG values obtained by reagent strip have to be corrected by +5.

Female↗
PubMed1992

Color Doppler sonography of ureteral jets in normal volunteers: importance of the relative specific gravity of urine in the ureter and bladder.

OBJECTIVE: Sonographic visualization of ureteral jets is a well-recognized phenomenon. In vitro studies have indicated that detection of fluid flow similar to ureteral jets depends on differences in density between the moving and the stationary fluid. This study was undertaken to determine if differences in density between ureteral urine and urine in the bladder could make a significant impact on the sonographic detectability of ureteral jets in vivo. SUBJECTS AND METHODS: Ten healthy volunteers were vigorously hydrated after an overnight fast. An initial color Doppler sonographic examination of ureteral jets was performed before voiding (while concentrated urine that had accumulated overnight was still in the bladder). A second examination was performed after two cycles of voiding and refilling the bladder (to ensure that dilute urine produced by the hydration was in the bladder). RESULTS: In all subjects, normal ureteral jets were readily identified on the initial examination. The difference in the estimated specific gravity between bladder urine and ureteral urine during the initial examination ranged from 0.002 to 0.016 (mean, 0.008). This was a statistically significant difference (p less than .05). On the second examination, ureteral jets were not detected from either ureter in any subject. The difference in the estimated specific gravity of bladder urine and ureteral urine during the second examination ranged from 0.000 to 0.002 (mean, 0.001). This was not a statistically significant difference (p greater than .05). There was no statistically significant difference in the diuresis rates throughout the course of the examinations. These ranged from 300 to 1218 ml/hr. CONCLUSION: These in vivo results support the hypothesis that detection of ureteral jets depends on density differences between ureteral and bladder urine. This is important clinically, because normal ureteral jets may be undetectable, despite adequate hydration and high rates of diuresis, if the patient is allowed to completely void and refill the bladder before the examination.

Adult↗
PubMed1988

Haemoglobin estimation--reliability of the copper sulphate specific gravity v. the cyanmethaemoglobin colorimetric method.

Automated colorimetric and copper sulphate (4 solutions with different specific gravities) methods were used to examine 218 blood specimens. The correlation between the two was high (r = 0.82)--proving that the copper sulphate method is reliable for haemoglobin screening. Copper sulphate gives better results in the higher haemoglobin region, which includes the majority of healthy people. In the lower haemoglobin region this method generally gives lower results than the cyanmethaemoglobin method. Copper sulphate is also by far the cheapest means currently available for mass screening.

Colorimetry↗
PubMed1983

Evaluation of a colorimetric reagent strip assay for urine specific gravity.

N-Multistix SG provides a convenient colorimetric assay for the determination of the specific gravity (sp. gr.) of freshly voided urine. When compared with results obtained by standard hydrometry, the colorimetric assay sp. gr. was observed to decrease by as much as 0.010 units as urine pH increased from 5 to 7. Moderate levels of proteinuria that did not alter hydrometer readings effectively raised the colorimetric sp. gr. by 0.005-0.010 units. The colorimetric assay was almost completely insensitive to clinically encountered concentrations of glucose and urea but responded appropriately to monovalent salts. The magnitude of these observed discrepancies places serious limitations on the value of the colorimetric sp. gr. measurement.

Colorimetry↗
PubMedDate not supplied

Urine specific gravity measurement: reagent strip versus refractometer.

OBJECTIVE: To compare the results of urinalysis screenings for specific gravity (SG) using the reagent strip and the refractometer. SETTING: United Hospital, Grand Forks, North Dakota. PRACTICE DESCRIPTION: United Hospital is a 384-bed teaching hospital. PRODUCT COMPARISON: The Ames Multistix 10 SG reagent strip (Miles, Inc., Elkhart, IN 46515) was compared with the TS Meter (Leica, Inc., Deerfield, IL 60015). MAIN OUTCOME MEASUREMENT: The degree of correlation between the results produced by each method. RESULTS: The percentage of difference between the means of the direct strip readings and the refractometer readings was 9.68%. The percentage of difference between the means of the adjusted strip readings and the refractometer readings was 22.58%, which was significantly different. When the direct strip readings and the refractometer readings were plotted together on a graph, the points were widely scattered; this fact, and a correlation coefficient of 0.725, suggest that random error occurred in both methods. Analysis of the slope and intercept of the correlation indicated systematic error. CONCLUSION: The reagent strip method of measuring SG is accurate only in a narrow range of "average" values, and should not be used as the basis for medical diagnoses.

Humans↗
PubMed1998

The effect of in vitro fermentation on specific gravity and sedimentation measurements of forage particles.

Dry matter degradability (DMD), gas production (GP), functional specific gravity (FSG), volume of gas associated (GA), water-holding capacity (WHC), and sedimentation measurements of orchard-grass (OG) and alfalfa (AA) hays (ground through a 8-mm screen) were studied before and after in vitro incubation with ruminal fluid for 2, 4, 8, 24, 48, and 72 h. The DMD was higher for AA than for OG (P < .001), but GP did not differ. The FSG of unfermented OG and AA was .59 and .73, respectively (P < .01). During fermentation, the FSG of OG increased more than did that of AA (from .93 to 1.39 for OG and from .97 to 1.27 for AA after 2 and 72 h, respectively), and GA decreased more rapidly (from .94 to -.04 mL/g DM and from .74 to .15 mL/g DM, respectively). The DMD was positively correlated with FSG (r = .83; P < .001) and, therefore, negatively with GA (r = -.72; P < .01). The WHC increased similarly in the two forages with fermentation time. Unfermented and fermented samples were incubated in sedimentation columns filled with distilled water for 19, 37, 75, 150, and 300 s. After 300 s of sedimentation time, the unfermented AA and OG samples tended to float (91.1 and 72.7% of DM, respectively). In contrast, fermented samples tended to sediment (90.7 and 90.9% of DM, respectively). There were only small effects of forage species and fermentation time on sedimentation tendency. Correlations between sedimentation measurements and DMD and FSG were not significant, with the only exception of DM recovered in the lower section of sedimentation columns after 75 s, which was particularly correlated with DMD (P < .01) and FSG (P < .05). The results suggest that degradation rate of fibrous particles is related to changes in FSG and GA and, therefore, could influence ruminal transit. However, FSG was unable to predict accurately the sedimentation behavior of samples.

Animal Feed↗
PubMed1989

Normal brain tissue response to photodynamic therapy: histology, vascular permeability and specific gravity.

The response of photodynamic therapy on normal brain was investigated in 140 Fisher rats. The rats were injected i.p. with Photofrin II (12.5 mg/kg) and 48 h later the dural area over the frontal cortex was photoactivated with red light (630 +/- 1 nm) from an argon dye laser. Treatment was performed with optical energy densities of 140 and 70 J/cm2. Histopathology, vascular permeability and specific gravity measurements were conducted on different populations of rats at 4 h, 24 h, 72 h and 1 week after photodynamic therapy (PDT). Histopathology revealed similar gross and microscopic pathology associated with light energies of 70 and 140 J/cm2 after all time points. A large cerebral infarct approximately the size of the brain surface area treated, evolved 24 h following treatment. Evans blue extravasation indicated a small area of vascular permeability evident as early as 4 h following PDT treatment at both energy levels, with increasing permeability evident at later time points. Specific gravity measurements taken on a representative area of the lesion indicated a significant (P less than 0.01) amount of edema present at 24 h post treatment with a gradual reduction approaching control values over the time period of 1 week. The data indicate a significant amount of damage to normal brain from low PDT treatment doses.

Animals↗
PubMed1981

[Fundamental problems and improved methods in the measurement of specific gravity of cerebral tissues. (author's transl)].

Gravimetric determination of brain tissue water content through the measurement of specific gravity (SG) still poses some basic problems. We have studied some of them with the aid of a new gradient column. Using a specially designed conical cylinder to distribute the solution in a graded manner, and a floating apparatus, a gradient column was automatically prepared with a high linearity (r greater than 0.99990). Analysis of equilibration time-course curves of cat brain tissue fragments with various sizes showed that it was more accurate to use volumes as large as 50 mg, and to measure as early as one minute after tissue insertion. In normal brain, SG of grey matter was usually higher than that of white matter. In contrast, in a brain with oligemia or with low hemoglobin contents of blood, this relationship was reversed. Thus, SG can be influenced not only by water content, but also by other factors. As SG of blood is higher than that of brain tissue, cerebral blood volume (CBV) is of particular interest. Assuming the total brain volume as equal to 1, CBV and volume of brain proper excluding intravascular blood can be expressed as x and 1-x respectively. In a given brain tissue, SG of blood or perfusate a, and SG of whole brain tissue A can be measured. If SG of brain proper is expressed as y, the following equation can be introduced: ax + y(1-x)=A. If a and A are obtained from two different brains under the condition of constant CBV, x, 1-x and y can be calculated. For this purpose, values from normal brain and those from perfused brain with isotonic saline were applied. The calculated CBV was 7% in the grey and 3% in the white. SG of brain proper was as low as 0.002 in the grey and 0.001 in the white as compared to that of whole brain tissue. When these values are applied to the equation of percent change in tissue volume as water = (SG of control tissue-1)-(SG of experimental tissue-1)/(SG of experimental tissue-1) x 100%, the false positive increase of water in a completely ischemic brain without edema is approximately 4% in the grey and 2% in the white. Then, care should be taken in the assessment of water increase from SG, particularly in the early stage of ischemic edema.

Animals↗
PubMedDate not supplied

Effect of Volume Loading with Water, Normal Saline, Palm Wine and Lipton Tea on Urinary Output, pH, Specific Gravity, Sodium and Potassium Concentrations in Human Subjects.

A comparative study of the diuretic effect of water, normal saline, palm wine and Lipton tea was carried out on forty (40) randomly selected, apparently normal undergraduate students of Medicine and Pharmacy at the University of Uyo, Nigeria. One and a half (1.5) litres of water, normal saline, palm wine and Lipton tea were given on separate days to the same subjects. The subjects were made to void their bladder before ingesting these substances and the urine sample collected was taken as control sample at the time zero. Thereafter, all the subjects emptied their bladder hourly for 3 hours. The urinary output, pH, specific gravity, sodium and potassium concentrations were determined. The results showed that water, palm wine and Lipton tea produced diuresis. Normal saline did not. Reduction of specific gravity and pH of urine accompanied these diuretic effects. Administration of normal saline and Lipton tea caused natriuresis. Potassium sparing diuresis was seen with Lipton tea and palm wine, whereas, water diuresis led to increased levels of potassium in urine. Volume loading with the above substances affected not only urinary output but also renal handling of sodium and potassium ions.

Journal Article↗
PubMed1982

Prolactin induces increase in the specific gravity of salamander, Hynobius retardatus, that raises adaptability to water.

The migration of the salamander, Hynobius retardatus, from land to water, which normally occurs in the breeding season, was induced by the injection of prolactin. The migration was accompanied by certain morphological changes (wider tail or swollen body); the observed morphological changes resembled those of salamanders collected from ponds during the breeding season. The prolactin-treated salamanders sank to the bottom of the water. In contrast, the control salamanders that did not receive prolactin floated near the water surface. The specific gravity of the whole body of the prolactin-treated animals was greater than unity. Prolactin injection induced a remarkable enlargement of the tissue between the skin and muscle, in which a considerable amount of mucopolysaccharide-rich substance accumulated. Because of the hydrophilic nature of the mucopolysaccharides, and increased mucopolysaccharide may absorb more water, which, in turn, may result in an increase of the osmotic pressure of the serum. This may eventually cause the animals to migrate from land to water to quench the "thirst." The absorption of water may make the specific gravity greater, and this allows the animals to sink in water.

Acclimatization↗
PubMed1995

Kinetics of hydration and functional specific gravity of fibrous feed by-products.

Five studies were conducted to evaluate the kinetics of digestion, hydration, and functional specific gravity (FSG) of various feed by-products (FBP) in vitro. The water-holding capacity (WHC) of alfalfa and orchardgrass (1.428 and 1.005 g/g of insoluble DM [IDM], respectively) was higher (P < .05) than the WHC of FBP, which ranged from .175 for distillers grains to .481 g/g of IDM for brewers grains pellets. Rate of hydration was the highest in brewers grains pellets and beet pulp (.215 and .252 min-1, respectively), whereas the lowest hydration rates were observed in orchardgrass, corn cob pellets, and soyhulls (.055 to .066 min-1). Loss of associated gasses from feed particles fermented in vitro increased (P < .05) their FSG when the contents of incubation tubes were transferred to pycnometers, compared with that when the incubation was carried out directly in the pycnometers (1.17 vs 1.13) to determine their FSG. Gas produced during fermentation delayed the increase in the FSG of all sources of brewers grains and beet pulp, corn gluten feed, distillers grains, orchardgrass, alfalfa, and wheat middlings but not of corn cob pellets, cottonseed hulls, and soyhulls. Averaged across hours of incubation, the FSG of FBP (except beet pulp) was either higher (P < .05) or tended to be higher than that of alfalfa and orchardgrass. Particle size of FBP did not influence FSG during fermentation in vitro. The WHC and FSG of feeds may be helpful in predicting the rate of passage of feeds through the rumen.

Animal Feed↗