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 163 records · Page 9Linked to original sources
PubMed1989

Passage and rumination of inert particles varying in size and specific gravity as determined from analysis of faecal appearance using multicompartment models.

Plastic particles of defined length (2, 5 mm) and specific gravity (sp.gr. 1.10, 1.34, 1.77) were administered just before feeding into the reticulo-rumen of four cattle and four swamp buffaloes given a diet predominantly of rice straw ad lib. Simultaneously, doses of ground rice straw marked with Cr and Yb were likewise given. Plastic particles were recovered from faeces for 12 d after dosing, and divided into non-ruminated (NR) and ruminated (R) particles. Excretion data of plastic particles were interpreted using a four-pool model incorporating passage of NR (kp) and R from the reticulo-rumen, post-ruminal passage, rate of chewing (kr) and two lag times. An inverse relationship was found between kr and sp.gr. The kr was higher for 5 mm than that for 2 mm particles. In contrast, kp was greatest for particles of sp.gr. 1.34, with higher kp for 2 mm than for 5 mm particles. Rates of passage and rumination (kp, kr) were higher for buffaloes than for cattle. Rumination time was related to kr, most highly (r2 0.96) with kr of 2 mm, 1.10 sp.gr. particles. Fragmentation of 5 mm particles by rumination tended to increase the rate of passage from the rumen. Ruminal passage rates of Yb and Cr markers were poorly correlated with each other and with kp of any of the plastic markers. Reanalysis of published data from plastic particle studies supported the relationships between sp.gr., size, kp and kr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed2006

Computed tomography-estimated specific gravity of noncontused brain areas as a marker of severity in human traumatic brain injury.

In this study, we assessed the relationship between brain estimated specific gravity (eSG) and clinical symptoms, therapeutic intensity level, and outcome in human traumatic brain injury (TBI). Brain weight, volume, and eSG of the noncontused hemispheric areas were measured from computed tomography (CT) DICOM images on the initial (5 +/- 6 h) CT of 120 patients with severe TBI. Control values were obtained from 40 healthy patients. The eSG of the noncontused hemispheric areas was significantly higher in TBI patients than in controls. eSG was higher in patients having a Marshall CT classification of 3 or 4 or a low initial Glasgow coma score. Two groups were defined according to the eSG of the noncontused hemispheric areas: less than (n = 83, 69%) or more than (n = 37, 31%) the threshold of normality (defined as 1.96 sd above normal = 1.0355 g/mL). The occurrence of mydriasis, use of osmotherapy at the scene of the accident, and therapeutic intensity level were higher in the increased eSG group. The outcome at intensive care unit discharge was worse in patients with an increased eSG although the difference was no longer significant at 1 yr. eSG determination by CT analysis might be relevant in the early management of TBI.

Adult↗
PubMed1992

Plasma concentration of furosemide versus specific gravity of urine in predicting dose of administration in race horses.

This study was undertaken to determine the applicability of plasma concentration of furosemide and specific gravity (SG) of urine in regulating the use of furosemide administered 4 hours prior to race time in Exercise-Induced Pulmonary Hemorrhage (EIPH) race horses. Nonbleeders (CTL) and certified bleeders (FUR) actively racing in Illinois (IL) and Pennsylvania (PA) were used in the study. Various doses (less than 250, 250, 300, 350, 400 and 500 mg) were administered either as a single intravenous (IV) dose or as a combination (IV-IM) of IV and intramuscular (IM) administrations 4 hours before race time. Plasma and urine samples were obtained post race for determination of furosemide concentration in plasma and measurement of SG of the urine in both CTL and FUR groups. Plasma samples were analyzed for furosemide using High Performance Liquid Chromatography with Fluorescence Detection. SG was measured using a digital refractometer. The results indicate a significant difference (p less than 0.0001) in the SG of the urine samples between the CTL and FUR groups irrespective of the route of administration (IV versus IV-IM). However, SG values of the urine in some CTL samples were lower than those in some FUR samples and vice versa. Thus, the use of SG alone is not reliable for predicting either the dose or the administration of furosemide to race horses. The plasma concentrations of furosemide following the administration (IV) of 250 mg or 500 mg 4 hours prior to race time were indistinguishable (25.91 +/- 4.45 versus 28.12 +/- 6.99 ng/ml, respectively); the majority of the horses in the groups had a plasma concentration of less than 40 ng/ml. When taken in total, plasma concentration of furosemide can only be used as a guide in regulating the administration of furosemide to race horses.

Animals↗
PubMed1999

Kaolin-induced hydrocephalus in the hamster: temporal sequence of changes in intracranial pressure, ventriculomegaly and whole-brain specific gravity.

The development of kaolin-induced hydrocephalus in adult hamsters was monitored by measuring changes in intracranial pressure (ICP), ventriculomegaly (VG) and whole-brain specific gravity (SG). Controls were intact or sham operated animals. Relative to controls, ICP of experimental animals increased at 24 h post intracisternal kaolin injection (by approximately 7-fold), reached a maximum on day 6 (by approximately 12-fold) and remained markedly elevated through day 15 (by approximately 5-fold). Ventricles differed in time of onset of distension (third: day 1, lateral: day 2, fourth: day 4) and in time of maximum ventriculomegaly (fourth: day 6; third: day 7; and lateral: day 9). Ventricular distension resulted in alterations in the ependyma; cilia were lost and apical cell surfaces were distorted. The ependyma was ruptured and the subjacent neuropil was exposed to the cerebrospinal fluid in some regions. Whole-brain SG remained constant in controls but declined in hydrocephalic hamsters after day 3 post-kaolin injection and reached its nadir on day 9 when whole-brain water content was 18% greater than in controls. Consistent with the fact that causal relationships exist between increased ICP, ventricular distension and brain edema, the alterations in each parameter occurred sequentially rather than simultaneously, and the time-course of each manifestation of hydrocephalus differed. The data suggest that the pathophysiology of kaolin-induced hydrocephalus in the hamster is tri-phasic: an initial period of rapid change, a brief interval of maximum alteration, and a subsequent period of compensation.

Age Factors↗
PubMed2004

Effects of alfalfa particle size and specific gravity on chewing activity, digestibility, and performance of Holstein dairy cows.

Two experiments were carried out to test the effects of alfalfa particle size and functional specific gravity (FSG) on chewing activity, digestibility, rumen kinetics, and production of lactating dairy cows fed corn silage based rations. In experiment 1, water-holding capacity (WHC), insoluble dry matter, hydration rate, and FSG changes were determined in alfalfa hay (varying in particle size) and corn silage. Reduction of particle size increased bulk density, FSG, and the rate of hydration, and decreased WHC of alfalfa. In experiment 2, 9 midlactation Holstein dairy cows fed total mixed rations containing 3 sizes of alfalfa hay (with geometric mean 7.83, 4.04, and 1.14 mm) were used in a replicated 3 x 3 Latin square design. The diets contained 20, 20, 35, 7, 7.5, 10, 0.3, 0.1, and 0.1% of DM alfalfa, corn silage, barley, soybean meal, beet pulp, wheat bran, dicalcium phosphate, vitamin premix, and salt, respectively. The geometric means (GM) of rations were 3.34, 2.47, and 1.66 mm in long, medium, and fine alfalfa treatments, respectively. Reduction of particle size increased daily NDF intake (kg), but decreased the proportion of physically effective factor (pef) and physically effective NDF (peNDF) in the ingested rations. Reduction of particle size increased the FSG of rations and intake of DM but reduced digestibility of NDF and ash. Reduction of particle size decreased ruminal mean retention time (RMRT), but increased the ruminal particulate passage rate. Milk and FCM yield were not affected by treatments. The rumen pH, total chewing activity, rumination, eating time, and milk fat were reduced as particle size decreased, but milk protein increased. This study showed that reduction of forage particle size increased bulk density, FSG, and hydration rate of alfalfa and was the most influential factor affecting DMI, milk composition, and chewing behavior. Reduction of forage particle size had minimal impact on digestibility and milk production.

Animal Feed↗
PubMed1961

Manifestations of injury in yeast cells exposed to subzero temperatures. II. Changes in specific gravity and in the concentration and quantity of cell solids.

Mazur, Peter (Oak Ridge National Laboratory, Oak Ridge, Tenn.). Manifestations of injury in yeast cells exposed to subzero temperatures. II. Changes in specific gravity and in the concentration and quantity of cell solids. J. Bacteriol. 82:673-684. 1961.-It has previously been established that subjecting cells of Saccharomyces cerevisiae to rapid cooling to -30 C results in cell death and in certain morphological alterations. The alterations consisted of the loss of the central vacuole and a 50% decrease in volume. The present experiments were concerned with determining whether the volume decrease was the result of the loss of water alone or of water plus cellular solutes. The density of the "frozenthawed" cells was found to increase from 1.14 to 1.25 g/cm(3) on the basis of measurements of the sedimentation rate of the cells. Interferometric and refractometric measurements indicated, furthermore, that the concentration of cell solids increased from 20 to 28%, whereas the total mass of cell solids decreased from 25 to 17 mumug/cell. The decrease in cell volume was thus shown to be the result of loss of solution from the cells, a solution containing 11 to 16% solids. Measurements of the rate of dialysis suggested that most or all of these solids had a molecular weight below 600. The findings are consistent with the view that low-temperature exposure destroyed the vacuolar membrane and sufficiently damaged the permeability barriers of the cell to permit escape of low molecular weight compounds. The damage was present a few seconds after thawing, and may, therefore, have been a direct result of intracellular ice crystals which, on the basis of previous studies, are believed to be responsible for death from low-temperature exposure.

Cold Temperature↗
PubMed2005

Accuracy of urine specific gravity and osmolality as indicators of hydration status.

To reduce the adverse consequences of exertion-related and acute intentional dehydration research has focused on monitoring hydration status. This investigation: 1) compared sensitivity of urine specific gravity (Usg), urine osmolality (U(osm)) and a criterion measurement of hydration, plasma osmolality (P(osm)), at progressive stages of acute hypertonic dehydration and 2) using a medical decision model, determined whether Usg or U(osm) accurately reflected hydration status compared to P(osm) among 51 subjects tested throughout the day. Incremental changes in P(osm) were observed as subjects dehydrated by 5% of body weight and rehydrated while Usg and U(osm) showed delayed dehydration-related changes. Using the medical decision model, sensitivity and specificity were not significant at selected cut-offs for Usg and U(osm). At the most accurate cut-off values, 1.015 and 1.020 for Usg and 700 m(osm)/kg and 800 m(osm)/kg for U(osm), only 65% of the athletes were correctly classified using Usg and 63% using U(osm). P(osm), Usg, and U(osm) appear sensitive to incremental changes in acute hypertonic dehydration, however, the misclassified outcomes for Usg and U(osm) raise concerns. Research focused on elucidating the factors affecting accurate assessment of hydration status appears warranted.

Adult↗
PubMed1984

Volume regulation in man during neck-out immersion in a medium with high specific gravity (Dead Sea water).

The effect of immersion for 4 h on arterial blood pressure and the rate or urinary sodium excretion was studied in five subjects both in fresh water and in Dead Sea water (specific gravity 1.19) at 34 C. Following 100 min of immersion, mean systolic and diastolic blood pressure decreased (P less than 0.01) in subjects immersed in fresh water, and increased (P less than 0.05) in those immersed in Dead Sea water. While immersion in fresh water led to hypotension, it was associated with an increased natriuresis. In contrast, the hypertensive response to immersion in Dead Sea water was not associated with an increased natriuresis. It is concluded that under the unique conditions of this experiment, urinary excretion of sodium becomes independent of systemic arterial blood pressure, and is presumably governed by neurohumoral influences originating in the baroreceptors of the low pressure system.

Adult↗
PubMed1993

Evaluation of gender differences in urine specific gravity and serum electrolytes in response to varied fluid intake and ibuprofen use.

Heat casualties and other conditions related to suboptimal fluid intake (FI) are common in the military. Current methods to assess FI do not address gender differences or medication use, specifically non-steroidal anti-inflammatory drugs (NSAIDs), which are commonly used in the field. Nine men and six women were prospectively studied while stationed in Saudi Arabia. Urine specific gravity and serum electrolytes were monitored as FI was varied before and after daily ibuprofen (IBP) ingestion. IBP impaired urinary dilution in both men and women, but differences were not statistically significant pre- and post-IBP or between genders. Use of IBP or other NSAIDs may confound usual methods to ensure adequate FI, and soldiers should be specifically questioned about their use before such assessments.

Adult↗
PubMed1984

Specific gravity increases and brain water content decreases during short epileptiform seizures in discrete rabbit brain areas.

In rabbits subjected to bicuculline (BC)- or pentylenetetrazole (PTZ)-seizures of 3 or 20 min duration or to adrenaline-induced hypertension, specific gravity (SG) was measured bilaterally in 15 regional brain areas in order to detect possible associations between the regionally limited blood-brain barrier openings due to these insults (see Nitsch and Klatzo 1983) and the presence of brain edema. In controls, a large variation between regional SG levels became evident: between 1.0467 in cerebellum and 1.0417 in preoptic area. A seizure duration of only 3 min was not sufficient to change SG significantly. After 20 min of seizures independent from the inducing agent, SG increased in all brain areas. The degree of increase seemed to be unrelated to presence or absence of a blood-brain barrier opening. In an attempt to avoid the influence of blood impregnation on the SG value, blood was replaced by saline before measurement. In controls, saline perfusion decreased SG only in the two areas with the highest original levels, thus documenting the partial dependency of the regional SG on the hematisation of the tissue. After 20 min of PTZ-induced seizures, SG in saline-perfused rabbits increased, but no longer significantly in all brain areas. This suggests that a part of the seizure-induced SG increase can be attributed to the hyperemia of the brain during the convulsions. On the other hand, an increase in flow volume due to hypertension did not change SG with the exception of the septum, preoptic area and hypothalamus. The direct measurement of water content with the classical wet/dry method in 4 gross brain areas showed that early seizure periods are in fact associated with a dehydration of the brain. This phenomenon could be explained by a glucose- and lactate-induced rise in blood osmolarity which in turn might cause a dehydration of the brain tissue.

Animals↗
PubMed1993

Density, specific gravity, and baricity of spinal anesthetic solutions at body temperature.

One of the most important physical properties affecting the level of analgesia achieved after intrathecal administration of a local anesthetic is its density relative to the density of the cerebrospinal fluid (CSF) at 37 degrees C. In this study, density, specific gravity, and baricity of local anesthetic solutions at body temperature were determined volumetrically to five significant figures. Standard solutions of 2% lidocaine, 0.5% and 0.75% bupivacaine, and 0.9% sodium chloride were tested. Bupivacaine, 0.75%-water dilutions and tetracaine, 0.2%, in water were also studied. The densities of all commercially prepared solutions were less than that of the normal range of CSF at 37 degrees C. The density of 0.2% tetracaine was the same as water. Continued dilution of 0.75% bupivacaine with water resulted in increasingly hypobaric solutions. However, only the 0.075% bupivacaine (1:9 dilution) solution had a density comparable to water. Knowledge of relative baricities aids in the selection of an appropriate local anesthetic for intrathecal use.

Anesthesia, Spinal↗
PubMed1995

Influence of moisture content of forage on ruminal functional specific gravity and passage of digesta.

Four crossbred beef steers (392 kg BW) fitted with ruminal cannulas were used in a 4 x 4 Latin square experiment with treatments arranged in a 2 x 2 factorial to evaluate effects of forage species (F) and reconstitution (R) on apparent digestibility, ruminal kinetics, and digesta functional specific gravity (FSG). Dietary treatments were alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) hays (90% DM) and the same hays reconstituted with water to 38% DM. Apparent DM digestibility was unaffected by R or F. Proportion of ruminal digesta with a FSG of .9 to 1.1 or 1.1 to 1.2 decreased linearly (P < .05) after feeding, whereas the proportion with FSG > 1.2 increased linearly (P < .01). Reconstitution decreased (P < .10) the proportion of ruminal digesta with FSG of 1.1 to 1.2 and increased (P < .10) the proportion with a FSG > 1.2 compared with the hay diets. Reconstitution decreased digesta passage rate for timothy forage; no influence on passage rate for alfalfa was detected (F x R, P < .10). Ruminal DM pool was increased by reconstitution (P < .10). Inert particles of 1-mm length passed from the rumen at a faster rate (P < .05) than 3-mm particles. Inert particles with SG of 1.32 passed from the rumen at a faster rate (P < .05) in the reconstituted alfalfa than in the dry alfalfa diet but at a slower rate in the reconstituted timothy than in the dry timothy diet. These results suggest that factors other than SG of the digesta can have a profound effect on passage of forage particles from the rumen.

Animal Feed↗
PubMed2001

Specific gravity of whole blood in cynomolgus monkeys (Macaca fascicularis), squirrel monkeys (Saimiri sciureus), and tamarins (Saguinus labiatus) and total blood volume in cynomolgus monkeys.

Blood collection is a common laboratory procedure in animal experiments. The purpose of this study is to establish baseline data for two essential hematologic parameters, total blood volume (TBV) and specific gravity of blood (SGB), of nonhuman primates. The SGB was determined by dropping samples of whole blood into cupric sulfate solution. The values for the mean SGB +/- 1 standard deviation are: cynomolgus monkeys, 1.0526 +/- 0.0019 [males (n = 39), 1.0531 +/- 0.0017; females (n = 48), 1.0522 +/- 0.001]; squirrel monkeys, 1.0555 +/- 0.0037 [males (n = 56), 1.0581 +/- 0.0027; females (n = 76), 1.0536 +/- 0.0032]; and tamarins, 1.0582 +/- 0.0020 [males (n = 13), 1.0582 +/- 0.0023; females (n = 17), 1.0581 +/- 0.0018]. To determine the TBV, blood was collected in tubes containing 1.5 mg EDTA after intravenous injection of Evans Blue solution. The TBV was obtained after correcting for the hematocrit and the dilution factor of the Evans Blue solution. The formulae were established to estimate TBV by referring to body weight (BW). There was no significance between TBV and BW in male monkeys weighing more than 6 kg.

Animals↗
PubMed1992

Molecular cloning and characterization of gravity specific cDNA in rice (Oryza sativa L.) suspension callus.

Rice (Oryza sativa L. var. Nipponbare) suspension callus was exposed to gravity stress at 450,000 g for 2 hours, after which poly(A)+RNA was isolated and a cDNA library was constructed. Three different gravity specific cDNAs, namely, GSC 128, GSC 233 and GSC 381 of 0.67, 0.60 and 0.68 kilobase pairs and transcripts of 1.9, 1.6 and 2.0 kb, respectively, were isolated by differential screening and Northern hybridization. The maximum level of transcript was achieved after 4 hours of exposure to gravity at 450,000 g for GSC 128, 2 hours for GSC 233 and 8 hours for GSC 381 followed by a gradual decrease to undetectable levels with the extension of gravitation time. Callus (GSC 128), shoot and callus (GSC 381) and root and callus (GSC 233) specific expression of transcripts was identified. Although the protection of callus by treatment with ABA, kinetin and sucrose extended the period of expression of mRNA in suspension callus after gravity exposure, the expression of gravity-inducible mRNA was exclusively regulated by the degree of callus viability or survival after the stress. In addition, we demonstrated that the level of GSC 381 transcript was markedly increased by exposing the cell to periodical gravity stress, suggesting that this mRNA is expressed and translated into special proteins which are closely related to the survival of the cell against gravity stress. The sequence of GSC 233 and GSC 381, consisting of 417 and 531 base pairs of the longest open reading frames, encode polypeptides with calculated molecular weights of 15.29 and 19.47 kDa, respectively. A sequence homology search against a data bank revealed that GSC 233 and GSC 381 differed from other stress inducible genes in terms of the coding sequence and expression characteristics.

Adaptation, Physiological↗