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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↗

PubMed2004

Comparison of specific gravity and creatinine for normalizing urinary reproductive hormone concentrations.

BACKGROUND: Specific gravity (SG) may perform as well as creatinine (CR) correction for adjusting urinary hormone concentrations, as well as offer some advantages. We compared the two methods and applied them to US and Bangladeshi specimens to evaluate their use in different populations. METHODS: Pearson correlations between serum concentrations and SG, CR, and uncorrected urinary concentrations were compared using paired daily urine and serum specimens from one menstrual cycle from 30 US women. Corrected urinary estrone conjugate and pregnanediol glucuronide concentrations were compared with serum estradiol and progesterone. Urine specimens across one menstrual cycle from 13 Bangladeshi women were used to evaluate the applicability of both methods to a nonindustrialized population. Linear mixed-effects models were used to compare CR and SG values in the Bangladeshi vs US specimens. RESULTS: There was no significant difference between SG-corrected vs serum and CR-corrected vs serum correlations for either assay. Usable CR results were obtained for all US specimens, but 37% of the Bangladeshi specimens were below the CR assay limit of detection. The Bangladeshi sample had significantly lower CR and higher inter- and intrasubject CR variability than the US sample. CONCLUSIONS: SG is a potentially useful alternative to CR correction for normalizing urinary steroid hormone concentrations, particularly in settings where CR values are highly variable or unusually low.

Adult↗

PubMed2006

Using urine specific gravity to evaluate the hydration status of workers working in an ultra-low humidity environment.

In environments with ultra-low humidity, workers may have excessive body water loss due to evaporation through the skin, which can lead to dehydration. Before the development of clinical symptoms and signs, concentrated urine may be applied as an early indicator of dehydration. We used urine specific gravity (USG) as a biomarker to evaluate the hydration status of workers working in such an environment. We collected the urine samples from workers at a lithium battery plant during their annual health examination, and the relative humidity of some working areas called "dry rooms" in the plant was 1.5 +/- 1%. We recruited workers in those dry rooms as the exposure group (N=50) and defined the remaining workers, including administration office workers, as the comparison group (N=122). The prevalence of abnormally concentrated urine (USG>1.030) and related factors were compared between these two groups. While the exposure group were younger and had shorter employment durations compared to the comparison group (p<0.05), they had a higher prevalence of abnormally concentrated urine (p<0.01). After adjusting for age, gender, employment duration, and body surface area, we found that working in the dry rooms was associated with an odds ratio of 11.9 (95% confidence interval: 2.5 to 56.9) of having abnormally concentrated urine. Therefore, USG is a good biomarker for evaluating the hydration status of workers working in ultra-low humidity environments, who need proper protection and adequate fluid supply to prevent excess water loss and its adverse health effects.

Adult↗

PubMed1984

[A longitudinal study of specific gravities of whole blood in dyestuff plant workers].

Specific gravities of whole blood (GB) have been used widely as a screening test of anemia in industrial surveillance systems in Japan. The recent spread of electronic computers enables us to make effective use of a large quantity of information and GB could be used to screen examinees more accurately if the various factors which can bring about fluctuations in GB or the data obtained through past health examinations are taken into consideration. Time trends of GB can be explained by the combination of the physiological effect of aging, environmental factors such as diet or working conditions, and the birth cohort effect. The present study was aimed to identify the factors which bring about fluctuations in GB through longitudinal as well as cross-sectional observations. The study subjects consisted of 1,105 male workers engaged in dyestuff production work or clerical work at a dyestuff plant located in Tokyo during the period from 1953 to 1976. Though a negative association was found between GB and the age of workers through cross-sectional observations, it was found through longitudinal observations that the individual GB had a tendency to rise during the period in each birth cohort. These facts suggest that some environmental factors acted so as to raise the individual GB during this period in opposition to the physiological effect of aging to lower it. In order to evaluate the associations of educational history, working conditions, age and physique of workers with GB, information on these factors obtained through health examinations in 1960, 1965, 1970 and 1975 was analyzed separately by the multi-dimensional contingency table method. As a result, it was demonstrated that GB was directly related to all of these factors in 1960 and 1965, to age and physique in 1970 and only to age in 1975. These results suggest that environmental factors associated with educational history or working conditions played a greater part in the earlier periods when the average GB was not as high as in the later periods. In summary, the efficiency of GB as a screening test will be considerably improved if the judgment criteria utilize information about these environmental factors as well as the physiological effect of aging based on the information obtained from this study.

Adult↗

PubMed2003

[Control of morphogenesis of woody plant by gravity on earth].

Using the weeping branch of Japanese flowering cherry tree and its woody stem of the seedling grown under simulated microgravity condition by three dimensional clinostat, it was elucidated that the morphogenesis of its secondary xylem supporting the plant itself to grow upward is seriously controlled by gravity on earth with a sedimentable amyloplast as its sensor. Space experiment of woody plant is expected to elucidate such problem.

Gravitation↗

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↗

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↗

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↗

PubMed1991

Positional nystagmus due to alteration of the specific gravity in the labyrinth.

Horizontal positional nystagmus having characteristics similar to ice water caloric nystagmus was induced by injecting heavy water into the rabbit middle ear cavity or facial nerve through the stylomastoid foramen. Furthermore, with general administration of glycerol to normal subjects, horizontal positional nystagmus as with general administration of heavy water to experimental animals was observed. It is possible that alteration of the specific gravity arising from infiltration of heavy water or glycerol into the labyrinth accounts for the manifestation of positional nystagmus. These studies on positional nystagmus may be one of the means to elucidate the mechanism of caloric nystagmus and to examine the function of the human blood-labyrinth-barrier.

Adolescent↗

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↗

PubMed1985

The role of cerebral blood volume changes in brain specific-gravity measurements.

Cerebral blood volume (CBV) was calculated in gerbils from specific-gravity (SG) changes between normal and saline-perfused brains. Furthermore, changes in CBV were investigated during ischemia using carbon-14-labeled dextran (MW 70,000) as an intravascular marker. Both data were used to evaluate the possible error due to a change in CBV on the measurement of ischemic brain edema by the SG method. The methodological error found was 0.0004 for a 100% CBV change. This error is insignificant, being less than the standard deviation in the SG measured for the gerbil cortex (SG 1.0494 +/- 0.0006). Thus, CBV changes are not responsible for the SG variations observed during the first phase of ischemia. These variations are better explained as an increase of brain water content during ischemia.

Animals↗

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↗

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↗

PubMed1991

Gravity dependent processes and intracellular motion.

Most organelles large enough to sediment or to undergo isothermal settling within eukaryotic cells are held in position by one or more components of the cytoskeleton. The interior of eukaryotic cells is considered to be very crowded, and the evaluation of natural-convective processes is very difficult. In a most simple view, the cell may be considered as consisting of four immiscible phases among which solutes are exchanged causing steep concentration gradients and thermodynamic conditions far from equilibrium. Extracellular gravity-related forces may include natural convection due to solute gradients external to single cells or the work performed by swimming, ciliated, or elongating cells.

Animals↗

PubMed1993

Preliminary observations on the effects of vector-averaged gravity on the embryonic and larval development of the gastropod mollusk, Ilyanassa obsoleta Stimpson.

Fertilized eggs of Ilyanassa obsoleta Stimpson were collected immediately after their deposition in egg capsules. Unopened egg capsules then were affixed to glass slides, and incubated either statically (controls) or on a clinostat (experimentals). After incubation for 9-14 days, hatching occurred sooner and in a higher percentage of clinostated capsules than in controls. Embryos that hatched while undergoing clinostat incubation were abnormal in morphology, whereas other embryos present in non-hatched capsules in the same tubes appeared normal, as did embryos in the control tubes. Although the results are compatible with a conclusion that vector-averaged gravity in the experimental tubes caused the altered development, some other aspects of how the incubations were done may have contributed to the differences between the control and experimental results.

Animals↗

PubMed1984

Gravity receptors: an ultrastructural basis for peripheral sensory processing.

Our ultrastructural study of serial sections has shown that type II hair cells of the anterior part of the utricular macula are integrated into the afferent neural circuitry of type I cells, which are arranged in clusters. Additionally, there exists a complex system of intramacularly originating efferent-type nerve fibers and terminals. The findings taken together suggest that, on morphological grounds, complex processing of sensory information occurs in gravity receptors. Asymmetry of such a complex system may contribute to motion and Space-motion sickness.

Acoustic Maculae↗

PubMed1993

Predicting skeletal adaptation in altered gravity environments.

It is generally agreed that the single factor that most limits human survivability in non-Earth environments is the phenomenon of bone demineralization and the medical problems induced by the subsequent imbalance in the calcium metabolism. Alterations of skeletal properties occur as a result of disturbances in the normal mechanical loading environment of bone. These alterations or "adaptations" obey physical laws, but the precise mathematical relationships remain to be determined. Principles governing unloading and overloading of bone are gaining more attention as a consequence of the planning of manned space stations, moon and Mars bases and spaceflights of long duration. This paper reviews the subject of bone remodeling and presents a mathematical framework which allows for the prediction of skeletal adaptation on Earth and in non-Earth gravity environments by power law relationships.

Adaptation, Physiological↗

PubMed1993

The effects of prolonged weightlessness and reduced gravity environments on human survival.

The manned exploration of the solar system and the surfaces of some of the smaller planets and larger satellites requires that we are able to keep the adverse human physiological response to long term exposure to near zero and greatly reduced gravity environments within acceptable limits consistent with metabolic function. This paper examines the physiological changes associated with microgravity conditions with particular reference to the weightless demineralizatoin of bone (WDB). It is suggested that many of these changes are the result of physical/mechanical processes and are not primarily a medical problem. There are thus two immediately obvious and workable, if relatively costly, solutions to the problem of weightlessness. The provision of a near 1 g field during prolonged space flights, and/or the development of rapid transit spacecraft capable of significant acceleration and short flight times. Although these developments could remove or greatly ameliorate the effects of weightlessness during long-distance space flights there remains a problem relating to the long term colonization of the surfaces of Mars, the Moon, and other small solar system bodies. It is not yet known whether or not there is a critical threshold value of 'g' below which viable human physiological function cannot be sustained. If such a threshold exists permanent colonization may only be possible if the threshold value of 'g' is less than that at the surface of the planet on which we wish to settle.

Adaptation, Physiological↗