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At least 973 records · Page 54Linked to original sources

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↗

PubMed1979

The effect of seasonal changes and socio-economic status on urinary pH and specific gravity.

Specific gravity and pH of urine in the dry and the wet season in three socio-economic Nigerian groups have been studied. Samples were collected at 7 a.m., 11 a.m. and 3 p.m. High-income subjects had a significantly lower urinary pH than low-income. During the wet season pH values were lower than in the dry, but not significantly so. During the day S.G. values did not differ, neither did they in different seasons. But there were significant differences between high and low income groups. S.G. and pH samples of high and low income groups were similar in children and in their parents. In medical students S.G. and pH in 24-hour urines were similar to the morning value of high and middle income groups and were not affected by season, but the volume was. The relevance of these findings is discussed relative to the rarity of urinary calculi in Nigerians.

Adult↗

PubMed1979

The gravity suit: a major advance in management of gynecologic blood loss.

We have used the gravity suit (G-suit) to stabilize patients in shock as a result of ruptured ectopic pregnancies. Four patients presenting in shock were carefully studied with serial vital signs, fluid replacement, and blood loss before and after application of the G-suit. These studies were continued through surgery and the removal of the G-suit. The G-suit improved vital signs, increased peripheral organ and limb perfusion, and decreased blood loss in all cases.

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↗

PubMed1978

[Fractionation of human erythrocytes according to their sedimentation behaviour caused by gravity. I. Methodical Investigations (author's transl)].

The usefulnes of a method to differentiate erythrocytes according to their specific gravity introduced by Danon et al. is demonstrated by using blood samples of healthy children and of others with different haematological diseases. Several conditions affecting the results are investigated. For clinical purposes the simple method is only applicable, if the results are presented as intervals of density.

Adolescent↗

PubMed1978

The clinical refractometer: a useful tool for the determination of specific gravity and osmolality in canine urine.

For the determination of specific gravity of canine urine the urinometer is often used. An alternative method is based on refractometry. Both methods were compared and a table for converting refractometer values to urinometer values is given. The refractometer was also compared with an osmometer. A linear relation was found between the readings of both instruments. The results clearly indicate that the refractometric method is very suitable for the small animal practitioner. The instrument appears to be a good alternative for both the urinometer and the osmometer.

Animals↗

PubMed1982

A reagent strip for measuring the specific gravity of urine.

A solid-phase reagent for determination of urinary specific gravity (relative density) is described. This reagent strip, similar to others in the "N-Multistix" series (Ames), contains a polyacid whose acidity is sensitive to the ionic concentration in the urine in which it is immersed. As the acidity of the polyacid changes, pH changes are detected by a pH indicator within the reagent strip. In comparison studies, 84.4% of relative densities as measured with these reagent strips were within 0.005 of the corresponding results with a total-solids meter, and 89.9% were within 0.005 of the corresponding urinometer results. Adding a correction of +0.005 to the reagent-strip results for urines with high pH increased the percentage of results within 0.005 of the comparison method to 90.7% (TS meter) and 92.9% (urinometer). Lot-to-lot variability and reader-to-reader variability were both low. Reagent strip results are not affected by glucose, may be increased by albumin, and correlate with urea concentrations.

Equipment and Supplies↗

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↗

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↗

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↗

PubMed1994

The role of gravity in gentamicin-induced toxic effects in a rabbit model.

OBJECTIVE: To define the role of gravity in gentamicin sulfate-induced retinal toxic effects by injecting the drug into vitrectomized rabbit eyes oriented in one of two positions. METHODS: Ten right eyes of New Zealand white rabbits underwent a two-port pars plana vitrectomy and were positioned with traction scleral sutures to rotate the medullary ray superiorly (five eyes) or nasally (five eyes). Six eyes received a pars plana intravitreal injection of 400 micrograms (0.1 mL) of gentamicin, and four eyes received 0.1 mL of balanced salt solution only. All eyes were kept in position for 30 minutes after the injection. Unoperated-on fellow eyes served as controls. Three or 5 days later, the eyes were enucleated and histopathologic examination was performed. RESULTS: Light and electron microscopy of gentamicin-treated eyes showed inner-retinal edema and disruption of the nerve-fiber and ganglion-cell layers within the more dependent retina vs sparing of the less dependent half of the retina. Eyes that received balanced salt solution showed rare inflammatory cells along the inner-retinal surface but essentially no inner-layer disruption. Examination of unoperated-on control eyes showed no inflammatory cells, edema, or necrosis. CONCLUSION: Gravitational effects and positioning contribute to the location of gentamicin-induced retinal toxic effects in vitrectomized eyes.

Animals↗

PubMed1996

Ciliates in rapid gravity filters of waterworks exploiting deep groundwaters.

Potable water is increasingly produced from deep (>100 m) tertiary groundwaters which often are completely reduced and contain high amounts of ammonium, methane, and hydrogen sulphide. They thus require special treatment which includes oxygenation and removal of the reduced contaminants by the biofilm developing in rapid gravity filters. The biofilm is heavily colonized with ciliates and microinvertebrates. A total of 38 species of ciliates was found in 42 samples taken from 4 waterworks in Germany during a period of 2 years. Only six species occurred in high numbers and in more than half of the samples: Acineria uncinata, Aspidisca lynceus, Cinetochilum margaritaceum, Colpidium colpoda, Glaucoma scintillans, and Holosticha pullaster. Five to thirteen species occurred per sample, and up to 6,000 individuals ml-1 biofilm were counted. There was a considerable fluctuation in the number of species and individuals, which could not be related to specific process parameters. The number of species and individuals decreased markedly from the filter surface to its centre. Colonization of the filters very likely occurs randomly via impure surface waters. The ciliate communities found consist mainly of alphamesosaprobic to polysaprobic species and thus closely resemble those known from activated-sludge processes. This is explained by the specific conditions near and in the biofilm, which is probably microaerobic and highly productive, providing microaerobic bacterial feeders with copious food. Obviously, it is the microenvironment which determines the occurrence of certain species. Thus, future research on the autecology of the indicator species used in the saprobic system should concentrate on their microenvironments.

Animals↗

PubMed1998

Hydroxyethylstarch sedimentation by gravity ex vivo for red cell reduction of granulocyte apheresis components.

BACKGROUND: When selecting only leukocyte compatible donors, the requirement of ABO compatibility limits the investigation and application of granulocyte transfusion therapy by reducing the pool of potential donors. Ex vivo hetastarch (HES) sedimentation was evaluated as a method of red blood cell (RBC) reduction of granulocyte components. The objective was to determine if this procedure consistently resulted in reduction of component packed RBC (PRBC) volume to < 5 ml, the range acceptable for infusion of ABO incompatible blood components based on guidelines set forth by the American Association of Blood Banks (AABB). STUDY DESIGN AND METHODS: HLA-matched, ABO-compatible sibling marrow donors were selected to donate granulocyte components, which were transfused into the allogeneic bone marrow transplant (BMT) recipient as prophylaxis against infection. Three granulocyte components were collected from each of 5 donors receiving G-CSF (daily x 5). Leukapheresis (LA) began 1 day after the first G-CSF dose (Day 1), and was repeated on Days 3 and 5. LA were performed using a continuous-flow blood cell separator, with 7L blood processed during each procedure. RBC sedimentation was facilitated by administration of a 6% HES solution to the donor line. The 5 granulocyte components collected on Day 1 were not manipulated after collection. The 10 components collected on Days 3 and 5 were manipulated by ex vivo gravity sedimentation for 60 minutes followed by transfer of the buffy coat (red cell poor [RCP] fraction) to a transfer bag with residual RBCs retained in the collection bag (red cell rich [RCR] fraction). The PRBC volume and cellular composition of the components and fractions were determined. RESULTS: When data for the 10 manipulated components were combined, the fraction of the components with < 5 ml PRBC was 0.4 in the RCP and 0.1 in the RCR fractions. All unmanipulated components contained > 5 ml PRBC. The mean PRBC volume (ml) of the RCP and RCR fractions were 6.3 and 16.4, respectively (P = .06). The mean number of RBC (x10(11)) in the RCP and the RCR fractions were .41 and 1.73, respectively (P = .03). The average proportion of cells in the manipulated components lost to the RCR fraction was 19.2% of granulocytes and 18.6% of platelets. CONCLUSION: Ex vivo HES sedimentation, as performed, significantly reduced the number of RBCs from granulocyte components, but did not consistently result in PRBC volumes in the RCP fraction within the range acceptable for infusion of ABO incompatible blood components based on the AABB guidelines. Moreover, significant numbers of granulocytes were lost to the RCR fraction.

Erythrocytes↗

PubMed1984

Enrichment of lysozyme-containing cells from the rabbit endocervix by unit gravity sedimentation.

Lysozyme is a bacteriolytic enzyme component of the secretory granules of endocervical mucous cells. In order to study the subcellular distribution of this enzyme in specific cell populations, endocervical cells from estrous and 5-day pseudopregnant rabbits were separated by unit gravity sedimentation. The application of this technique to pronase-dispersed endocervical cells from estrous rabbits resulted in the isolation and enrichment of two mucous cell types that were distinguished morphologically into type I and type II cell populations. Lysozyme was identified in both cell types, using an unlabeled antibody enzyme method, and the degree of staining paralleled the number of mucous granules. In the absence of estrogen dominance in 5-day pseudopregnant rabbits, there was a 50% reduction in the number of mucous cells with a concomitant reduction in both the number of secretory granules per cell and the intracellular concentration of lysozyme. In the absence of ovarian steroid hormones, i.e., 15-16 weeks after ovariectomy, endocervical cells were devoid of secretory granules and lysozyme staining was negative. Enriched populations of endocervical cells represent a potential experimental model for studying the hormonal role in the regulation of lysozyme synthesis by specific cell populations.

Animals↗

PubMed2004

Parameter oscillations in a very high gravity medium continuous ethanol fermentation and their attenuation on a multistage packed column bioreactor system.

The quasi-steady-states, marked by small fluctuations of residual glucose, ethanol, and biomass concentrations, and sustainable oscillations marked by big fluctuations of these monitored fermentation parameters were observed during the continuous ethanol fermentation of Saccharomyces cerevisiae when very high gravity media were fed and correspondingly high ethanol concentrations reached. A high ethanol concentration was shown to be one of the main factors that incited these oscillations, although the residual glucose level affected the patterns of these oscillations to some extent. The lag response of S. cerevisiae to high ethanol stress that causes the shifts of morphology, viability loss, and death of yeast cells is assumed to be one of the probable mechanisms behind these oscillations. It was predicted that the longer the delay of this response was, the longer the oscillation periods would be, which was validated by the experimental data and the comparison with the oscillatory behaviors reported for the ethanologen bacterium, Zymomonas mobilis. Furthermore, three tubular bioreactors in series were arranged to follow a stirred tank bioreactor to attenuate these oscillations. However, exaggerated oscillations were observed for the residual glucose, ethanol, and biomass concentrations measured in the broth from these tubular bioreactors. After the tubular reactors were packed with Intalox ceramic saddle packing, these oscillations were effectively attenuated and quasi-steady-states were observed during which there were very small fluctuations of residual glucose, ethanol, and biomass within the entire experimental run.

Apoptosis↗

PubMed2005

Metabolite profiling for analysis of yeast stress response during very high gravity ethanol fermentations.

A laboratory strain and an industrial strain of Saccharomyces cerevisiae were grown at high substrate concentration, so-called very high gravity (VHG) fermentation. Simultaneous saccharification and fermentation (SSF) was applied in a batch process using 280 g/L maltodextrin as carbon source. It was shown that known ethanol and osmotic stress responses such as decreased growth rate, lower viability, higher energy consumption, and intracellular trehalose accumulation occur in VHG SSF for both strains when compared with standard laboratory medium (20 g/L glucose). The laboratory strain was the most affected. GC-MS metabolite profiling was applied for assessing the yeast stress response influence on cellular metabolism. It was found that metabolite profiles originating from different strains and/or fermentation conditions were unique and could be distinguished with the help of multivariate data analysis. Several differences in the metabolic responses to stressing conditions were revealed, particularly the increased energy consumption of stressed cells was also reflected in increased intracellular concentrations of pyruvate and related metabolites.

Cell Culture Techniques↗

PubMed2006

Model of the mass transport to the surface of animal cells cultured in a rotating bioreactor operated in micro gravity.

A mathematical model is used to investigate the transport of dissolved oxygen from the bulk fluid to the surface of aggregates of animal cells cultured in a rotating bioreactor. These aggregates move through different regions of the bioreactor with a local flow field and concentration distribution that vary with time. The time variation of the Sherwood number and the surface concentration for a range of parameters typical of a cell science experiment executed in the Rotating Wall Perfused Vessel (RWPV) bioreactor in space are investigated. The Reynolds numbers experienced by the aggregate are generally low (Re < 1) and the Peclet numbers range from O(1) to O(100). Comparison of the results from the numerical solution of the mathematical model with those from a quasi-steady model, using a steady-state correlation for mass transport on a sphere, indicate that the quasi-steady assumption is not a good model to compute the instantaneous Sherwood number. This indicates a significant history effect in the Sherwood number response to the variations of acceleration of the aggregates in the bioreactor. A high resistance to the mass transport from the bulk fluid to the surface of the aggregate exists for the bioreactor operated in micro gravity. The difference between the surface concentration and the free stream concentration was as high as 30% for aggregates larger than 3 mm. Diffusion reduces the variations of the free stream concentration resulting in a nearly constant value for the concentration at the surface of the aggregates.

Animals↗

PubMed1981

Afferent synaptic connections between hair cells and the somata of intramacular neurons in the gravity receptor system of the statocyst of Octopus vulgaris.

In the sensory epithelium (macula) of the gravity receptor system of the statocyst of Octopus vulgaris, there are two types of afferent neurons, distinguished according to their position in the epithelium. The somata of one type lie accumulated in a ring peripheral to the hair cell layer of the epithelium; these are designated as perimacular neurons. The somata of the other type lie among the hair cells, below the level of their nuclei; these are designated as intramacular neurons. Axons of afferent neurons which touch the hair cells are postsynaptic to some of the hair cells touched. As the somata of the intramacular neurons also touch the hair cells, they were investigated by serial electron microscopic reconstruction to determine if afferent synaptic contacts between hair cells and these somata occur. An average of about 600 intramacular neurons was counted in two maculae. Afferent synapses were seen to occur between hair cells and the somata of 76% of the intramacular neurons investigated. The postsynaptic processes of the intramacular neurons' somata were of two morphological types; one with a finger-like and one with a flat postsynaptic process (average of one synapse of each type per soma). The soma of an intramacular neurons can be postsynaptic to more than one hair cell simultaneously (average of 1--2 hair cells per soma). In addition to being presynaptic to only one neuron's soma, a hair cell could be simultaneously presynaptic to the axons of one or more afferent neurons. The morphological findings are discussed as to their possible physiological consequences.

Afferent Pathways↗