Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Separation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,747 records · Page 97Linked to original sources
PubMed1999

[Separation and analysis of saccharides--on mainly oligosaccharides].

Characteristics of three kinds of columns used for the separation and analyses of saccharides by HPLC, and of a pulsed amperometric detector (PAD) as a high sensitive detector for the microanalysis of saccharides were described. The following several examples of studies on the separation and analyses of saccharides were illustrated: (1) separation of maltosaccharides on an amino column, (2) isolation of each maltooligomer of DP6-17 on an ODS column, (3) retention behavior of alpha-cyclodextrin (alpha CD) and branched alpha CDs on an ODS column, (4) separation of three positional isomers of dimaltosyl-beta CD on an ODS column and a graphitized carbon (GC) column, (5) separation of diastereoisomers of glucosyl-inositol on a GC column, (6) chromatographic behavior of nine glucobioses on a GC column, (7) estimation of the distributions of chain length of amylopectins with the pulsed amperometric detection, (8) microanalysis of beta CD and glucosyl-beta CD in biological matrices by HPLC with PAD. In addition, methods for the structural analyses of branched CDs by FAB-MS, 13C-NMR and enzymatic degradation were expressed.

Animals↗
PubMed1995

Metric for separation discrimination by the human visual system.

It is now clear that models of positional coding for elements sufficiently separated to permit individual identification require not only a first stage of linear filtering but also a second stage of representation that is preceded by a rectifying type of nonlinearity. To address the issue of the metric of this second stage we measure separation discrimination for Gabor stimuli of different sizes and of different peak spatial frequencies and separation, with and without different types of lateral distractors. Our results show that there is only a weak dependence of separation discrimination on the spatial frequency of equidetectable, spatially narrow-band stimuli; however, carrier spatial frequency can affect the influence that lateral distractors have on separation judgments. We conclude that (1) the second-stage representation is a space-size one consistent with the fact that there are scaled distributions of energy detectors of different sizes and (2) the influence of distractor elements suggests a spatial-frequency influence either at the second-stage representation or at a site beyond this second stage.

Contrast Sensitivity↗
PubMed1982

[The separation of neuropeptides by high performance liquid chromatography and its application to the analysis of peptides in the rat pituitary neurointermediate lobe (author's transl)].

High performance liquid chromatography (HPLC) was used for the separation of many neuropeptides. Chromatography was carried out using a Hitachi Model 638 high performance liquid chromatograph. Peptides and samples from tissue dissolved in an aqueous buffer were injected into a stainless-steel column (4 X 250mm) packed with Hitachi #3053 (octadecylsilane). The aqueous buffer consisted of NaH2PO4 and H3PO4. After a loading phase (0% organic solvent) of 1 min, the peptides were sequentially eluted at room temperature using a gradient of organic solvent (acetonitrile or methanol, 0-60%). The eluted polypeptides were detected by UV absorbance at 220nm, and then they were collected for subsequent bio and radioimmunoassay using a fraction collector. The gradient of methanol or acetonitrile in 0.02M NaH2PO4, 0.1% H2PO4 was useful for separating small molecular peptides. The gradient of acetonitrile in 0.05-0.1M NaH2PO4, 0.1% H2PO4 was useful for separating many neuropeptides including ACTH related peptides. Retention times of chromatographed polypeptides showed good reproducibility. Good reproducibility was also found in peak areas of these peptides. A linear relationship was observed between the doses of peptides and their peak areas. The extracts of rat pituitary neurointermediate lobe showed several peaks of UV absorbance on PHLC; some of them coincided with AVP, oxytocin, alph-MSH, CLIP and beta-endorphin but others were unidentified. AVP immunoreactivity showed one peak which coincided with the AVP peak of UV absorbance, but ACTH immunoreactivity showed 5-6 peaks. Thus, many polypeptides were well separated using HPLC by changing the eluting condition. The simplicity, speed, good reproducibility and good quality of the separations render this technique suitable for purification and quantitative analysis of neuropeptides, and the combination of HPLC, radioimmunoassay and bioassay gives very fine analysis of neuropeptides.

Animals↗
PubMedDate not supplied

[Sedimentation analyser--calibration and testing of a newly developed device for recording separation behavior of blood and other dispersed systems].

A computer-aided sedimentation analyser is described, which can be used for the continuous monitoring of the separation of blood and other dispersed systems by recording the separation-dependent infrared transmission in the range between 100 xg to 700 xg. Up to eight samples can be measured simultaneously within a short period of time, and only a small amount of suspension is required (15 minutes, 350 microliters). For centrifugal acceleration more than 100 xg and a haematocrit range of between 0.2 and 0.7, the evolution of the height of the plasma column (HPC) over time is expressed in non-linear regression form by HPC(t) = HPC infinity*(1-e-kt) + c. The separation constant k is influenced by plasma viscosity, haematocrit, aggregability and erythrocyte deformability, is directly proportional to centrifugal acceleration, and declines in hyperbolic fashion with increasing haematocrit between 300 xg and 650 xg. The separation constant is closely related to the maximum velocity which, in fact, represents the sensitive parameter of separation. Thus, the sedimentation analyser can be applied as an alternative to the traditional measurement of erythrocyte sedimentation rate according to Westergren.

Blood Sedimentation↗
PubMed2005

Alcohol use and intimate partner violence as predictors of separation among U.S. couples: a longitudinal model.

OBJECTIVE: The purpose of this study was to investigate the relationship between partner violence (male-to-female and female-to-male) and heavy drinking (consuming five or more drinks per occasion) and the effect of this relationship on marital separation. METHOD: Married and cohabiting couples were selected through multistage random probability sampling from U.S. households. In 1995, 1,635 couples were interviewed; 1,392 of these couples were re-interviewed in 2000. The final analysis included couples who were still married or living with the same partner (intact n = 1,136) from the baseline, and couples who had broken up (nonintact n = 191) sometime during the 5-year follow-up period. RESULTS: The findings indicate that couples who reported female-perpetrated violence, female alcohol-related problems and male heavy-drinking episodes (one to three times a month) were 2.5-3 times more at risk for separation. On the other hand, female heavy drinking (one to three times a month) is less likely to predict separation. Cohabiting couples are also more at risk for separation than married couples. Couples with longer relationships are less at risk for separation. CONCLUSIONS: Marital counseling, therapy or intervention programs must address issues pertaining to partner violence and alcohol use among couples while concurrently providing information about healthy relationships and helping couples develop skills to attain them. The importance of preventing partner violence is increasingly recognized in the field of public health.

Adolescent↗
PubMed1975

Epididymal carbohydrate metabolism. III. Metabolism of the caput and cauda epididymidis after separation from the testis in the rat.

After unilateral separation of the rat epididymis from the testis, the metabolism of various substrates in vitro by tissue from the attached and separated caput and cauda epididymidis at 7 and 28 days after surgery was determined by radiorespirometry. Hourly collections of 14-CO2 were made during 5-hr incubations. The patterns of 14-CO2 evolution from glucose indicated that most of the metabolic activity followed the Embden-Meyerhof glycolytic and the Krebs cycle respiration pathways. The alteration of the rate of glycolysis was always greater than that of respiration. In all samples, the metabolism of (2-14C) glucose was approximately equal to that of (6-14C) glucose (G-6)and less than that of (1-14C) glucose (G-1). Pentose cycle activity was indicated in all tissues from the caput and cauda epididymidis by the preferential utilization of G-1 over G-6. At 7 and 28 days after surgery, respectively, the G-1:G-6 ratios of 14-CO2 evolution after incubation for 2 hr were 9.75 and 7.79 for the separated caput, 5.17 and 2.66 for the intact caput, 3.11 and 2.52 for the separated cauda and 3.73 and 2.84 for the attached cauda epididymidis. Although epididymal separation did not effect the metabolism of (U-14C) glucose or (U-14C) fructose, glucose appeared to be a more important epididymal substrate than fructose.

Acetates↗
PubMed1993

Induction of ovulation and superovulation in mares using equine LH and FSH separated by hydrophobic interaction chromatography.

Pharmacological control of reproduction in mares requires the use of equine gonadotrophins to avoid induced immunological resistance. Crude equine gonadotrophins (CEG) have been used but the presence of equine luteinizing hormone (eLH) and follicle-stimulating hormone (eFSH) in CEG has led to disappointing results in superovulation studies. Separation of eLH and eFSH activities from CEG is necessary to overcome this problem. The hydrophobic properties of the two hormones were sufficiently different to permit their separation by hydrophobic interaction chromatography (HIC) on a phenyl Sepharose matrix. Good yields of separate FSH and LH fractions were readily obtained by stepwise elution and the method was adapted for large scale preparations of enriched fractions of eLH and eFSH. Two experiments were performed in vivo to evaluate the biological activity of the HIC fractions. Experiment 1 showed that biological activity of the LH fraction in inducing ovulation of preovulatory follicles was similar to that obtained with CEG, indicating that LH bioactivity was not altered by HIC. Experiment 2 demonstrated that biological activity of the FSH fraction was identical (as far as rate of ovulation was concerned) to that of CEG in superovulating mares, indicating that FSH activity was also not altered by HIC. Although we have not obtained better results with the separate equine gonadotrophins than with CEG, it is potentially advantageous to use preparations with single activity to obtain a controlled balance of FSH and LH activity. The HIC technique was chosen because it could easily be scaled up to provide the large amounts of the separate hormones needed for the treatment of a large number of mares.

Animals↗
PubMed1992

[The influence of serum separators on biochemical values in experimental animals].

The influence of three serum separators, A, B and C, on biochemical values was examined. With A or B, changes in the values of ChE, LAP, UN, K, P, Cl and Ca in rat serum; ChE, UN, Cl and Ca in dog serum; and K and P in monkey serum took place over a period of 20 min after blood collection. Therefore, the biochemical values of whole blood were considered to be stable after 20 min. Thus, biochemical tests were conducted on serum from the three serum separators after allowing the blood to stand 20 min. The values obtained for each separator were not markedly different from those of the control. These results suggest that a serum separator is useful for separation of serum of experimental animals under the proper conditions.

Animals↗
PubMed2002

Effect of cocaine on periadolescent rats with or without early maternal separation.

Cocaine-induced behavioral sensitization and weight loss were investigated in periadolescent Wistar rats kept with their mothers or subjected to repeated maternal separation. Litters allocated to the separation procedure were placed in a temperature-controlled (33 degrees C) chamber for 3 h per day from postnatal day 6 (P6) to P20. Non-handled rats were left undisturbed until weaning. Treatments were started on P30-31 and the test was performed on P36-37. Animals received injections of saline or cocaine (10 mg/kg, sc) twice daily for 5 days. On day 6 all animals received saline. On day 7 animals were challenged with 10 mg/kg cocaine and their locomotion was evaluated in activity cages. A third group received saline throughout the 7-day period. Body weights were recorded on P30-31 and P36-37. Two-way ANOVA on body weights showed a main effect of treatment group (F(1,35) = 10.446, P = 0.003; N = 10-12). Non-handled rats treated with cocaine for 5 days gained significantly less weight, while no significant effect was observed in maternally separated rats. Two-way ANOVA revealed a main effect of drug treatment on locomotor activity (F(2,32) = 15.209, P<0.001; N = 6-8), but not on rearing condition (F(1,32)<0.001, P = 0.998). Animals pretreated with cocaine showed a clear behavioral sensitization relative to the saline group. No difference in the magnitude of sensitization was found between separated and non-handled animals. Only the effect of cocaine on weight gain was significantly affected by repeated episodes of early maternal separation during the pre-weaning period.

Analysis of Variance↗
PubMed2004

Inhibition of centrosome separation after DNA damage: a role for Nek2.

DNA damage results in cell cycle arrest in G2. Centrosomes also separate in G2, raising the question of whether separation occurs during the DNA damage-induced G2 arrest. Nek2, the mammalian homologue of NIMA, is a cell cycle-regulated serine/threonine protein kinase that regulates centrosome separation during G2. Here we show that damaged cells fail to activate Nek2. Both Nek2 levels and activity are reduced after DNA damage. Radiation inhibits the premature centrosome splitting induced by overexpression of Nek2, indicating that Nek2 is involved in activation of the G2 checkpoint and is not secondary to cell cycle arrest. We confirm using siRNA that centrosome separation and cell growth are impaired in the absence of Nek2. These studies define a previously unreported DNA damage response of inhibition of centrosome separation mechanistically linked to Nek2.

Base Sequence↗
PubMed2006

Electrophoretic separation of human skeletal muscle myosin heavy chain isoforms: the importance of reducing agents.

An electrophoretic protocol previously used for the separation of rat myosin heavy chain (MHC) isoforms was slightly modified to improve the separation of human MHC isoforms in both large and minigel systems. The addition of reducing agents (beta-mercaptoethanol or dithiothreitol) to the top running buffer (TRB) radically improved separated MHC isoform resolution and the intensity of electrophoretic runs lasting longer than 5 h. In minigel systems, the MHC isoforms could be separated in as little as 5 h. The improved resolution of bands with the inclusion of reducing agents to the TRB facilitated the identification of clear boundaries for densitometric quantification of relative MHC isoform content, particularly for MHC IIa and MHC IIx. No significant effect of these reducing agents added to the TRB was observed for runs lasting only 100 min. Thus the inclusion of reducing agents in the TRB is essential for long electrophoretic runs, usually when separating large molecular mass proteins.

Electrophoresis↗
PubMed1999

Separation of deterrents to ingestive behavior of cattle from cattle feces.

Feeding-deterrent chemicals were extracted from cattle feces and then separated with three chromatographic methods. Behavioral two-choice test bioassays with cattle were used to examine the deterrent properties of the fractions. Cattle feces were extracted with diethyl ether, and the extracts were separated into neutral, acidic, and basic fractions. Of the three fractions, only the neutral fraction was a deterrent. Separation of the ether-soluble neutral chemicals was conducted with an open column of silica gel using four carrier solutions consisting of pentane and ether. Fraction B (eluted with the carrier solution; pentane:ether = 90:10) was the most effective deterrent among the four fractions. This fraction was divided into 10 fractions by liquid chromatography. Fractions 6, 7, and 8 seemed to deter cattle from feeding. The combined Fractions 6, 7, and 8 were separated into 15 fractions with HPLC. Deterrent activities were detected in Fractions 2, 3, 9, 10, 11, 12, 13, and 14, suggesting that deterrents were separated into two groups using HPLC. These results suggested that several specific chemicals in feces are involved in inhibiting cattle from ingesting grass near cattle feces.

Animals↗
PubMed2006

Effects of concentrated separator by-product (desugared molasses) on intake, site of digestion, microbial efficiency, and nitrogen balance in ruminants fed forage-based diets.

In Exp. 1, 4 ruminally and duodenally cannulated beef steers (444.0 +/- 9.8 kg) were used in a 4 x 4 Latin square with a 2 x 2 factorial treatment arrangement to evaluate the effects of forage type (alfalfa or corn stover) and concentrated separator byproduct (CSB) supplementation (0 or 10% of dietary DM) on intake, site of digestion, and microbial efficiency. In Exp. 2, 5 wethers (44 +/- 1.5 kg) were used in a 5 x 5 Latin square to evaluate the effects of CSB on intake, digestion, and N balance. Treatments were 0, 10, and 20% CSB (DM basis) mixed with forage; 10% CSB offered separately from the forage; and a urea control, in which urea was added to the forage at equal N compared with the 10% CSB treatment. In Exp. 1, intakes of OM and N (g/kg of BW) were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had greater (P < 0.08) OM and N intakes (g/kg of BW) compared with 0% CSB-fed steers. Total duodenal, microbial, and nonmicrobial flows of OM and N were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had increased (P = 0.02) duodenal microbial flow (N and OM) compared with 0% CSB-fed steers. Forage x CSB interactions (P < 0.01) existed for total tract N digestibility; alfalfa with or without CSB was similar (67.4 vs. 69.5), whereas corn stover with CSB was greater than corn stover without CSB (31.9 vs. -23.9%). True ruminal OM digestion was greater (P < 0.09) in steers fed alfalfa vs. corn stover (73.0 vs. 63.1%) and in steers fed 10 vs. 0% CSB (70.3 vs. 65.8%). Microbial efficiency was unaffected (P > 0.25) by forage type or CSB supplementation. In Exp. 2, forage and total intake increased (linear; P < 0.01) as CSB increased and were greater (P < 0.04) in 10% CSB mixed with forage compared with 10% CSB fed separately. Feeding 10% CSB separately resulted in similar DM and OM apparent total tract digestibility compared with 10% CSB fed mixed. Increasing CSB led to an increase (linear; P < 0.02) in DM, OM, apparent N digestion, and water intake. Nitrogen balance (g and percentage of N intake) increased (linear; P < 0.08) with CSB addition. Feeding 10% CSB separately resulted in greater (P < 0.01) N balance compared with 10% CSB fed mixed. Using urea resulted in similar (P = 0.30) N balance compared with 10% CSB fed mixed. Inclusion of CSB improves intake, digestion, and increases microbial N production in ruminants fed forage-based diets.

Animal Feed↗
PubMed1984

Influence of reduced litter size and daily litter separation on fertility of sows at 2 to 5 weeks postpartum.

Two experiments were conducted to determine the influence of various lactational treatments on the incidence of estrus and subsequent fertility of sows. Experiment 1 consisted of 60 crossbred (Yorkshire X Duroc) sows assigned to one of four treatment groups. Litter size was reduced (RLS) to two to four nursing pigs/sow at 2 (n = 16), 3 (n = 15) or 4 (n = 15) wk of lactation for 5 d before final weaning or litters were weaned from control sows (n = 14) at 5 wk of age. Reduced litter size resulted in 19 of 43 (44%) sows detected in estrus on the day of weaning. More (P less than .05) RLS sows were in estrus 0 to 3 d after weaning than control sows. Fertility traits (number of corpora lutea, eggs recovered, egg recovery rate, eggs fertilized, fertilization rate, cleaved eggs and cleavage rate) were similar among treatment groups at 4 to 6 d postestrus. Experiment 2 consisted of 59 crossbred (Yorkshire X Duroc) sows assigned to one of four treatment groups. Litters were separated from their dams for 6 (n = 20) or 12 (n = 10) h/d between 2 and 4 wk or litters were weaned at 2 (n = 13) and 4 (n = 15) wk of age. Lactational estrus was detected in 13 of 20 (65%) sows and 5 of 10 (50%) sows that were separated from their litters for 6 or 12 h/d, respectively. Lactational estrus (LE, n = 18) in sows was observed 4 to 8 d after initial separation, while sows remaining anestrus during lactation (LA, n = 12) were in estrus 2 to 7 d postweaning. Average intervals from separation or weaning to estrus for LE and LA sows and for sows whose litters were weaned at 2 or 4 wk were 5.9, 4.4, 4.4 and 4.2 d, respectively, and were longer (P less than .05) for LE sows. Fertility traits were similar among treatment groups. These studies demonstrate that lactations of 2 to 5 wk and lactational treatments of sows, including either litter reduction before weaning or daily separation of sows from their litters, resulted in similar postweaning or post-treatment intervals to estrus and similar fecundity regardless of treatment or lactation length. While 50% of the sows responded to treatments, reasons for the lack of response in the remaining sows is not explained, but it appears that body weight and backfat of sows at weaning, and feed intake during lactation were unrelated to the success of the treatments imposed.

Animals↗
PubMed1988

Effect of maternal separation on the complement system and antibody responses in infant primates.

Hemolytic complement activity and complement protein levels were evaluated before and after psychological disturbance in the squirrel monkey. Significant increases in hemolytic complement activity were observed following separation of 6-month-old infants from their mothers. Complement protein levels were generally correlated with hemolytic activity, but did not show the same pattern of change. C3 levels did not change consistently after maternal separation, while C4 decreased significantly on Day 7, and then began to return toward basal levels by Day 14. The alterations in complement activity were associated with elevated adrenal hormone secretion, but were not directly correlated with plasma cortisol levels. A second experiment showed that increased hemolytic complement activity also occurred in juvenile squirrel monkeys following 4-hour to 7-day removals from a peer group. The effect of maternal separation on antibody responses to viral challenge was evaluated in a third experiment. Separated infant squirrel monkeys mounted a smaller antibody response than did control infants that remained with their mothers. A similar decline in antibody responses was observed in separated rhesus macaque infants, but the effect was less marked in this species. Thus, the strong effect of psychological disturbance on immunity in the squirrel monkey is probably related to its prolonged endocrine responses.

Animals↗
PubMedDate not supplied

In vitro response to hyperthermia or X-irradiation of diploid and tetraploid RIF-1 cells separated by centrifugal elutriation.

The RIF-1 cell line at the University of Utah is comprised of approximately 65 per cent diploid and 35 per cent tetraploid cells. Because sensitivity to heat cell killing has been shown to be ploidy dependent (Lucke-Huhle 1978), the responses of these subpopulations were examined independently. Diploid and tetraploid cells were separated from stock in vitro cultures by centrifugal elutriation and maintained entirely in vitro. No influence of ploidy on Do or Dq of heat dose survival curves could be detected. Neither did ploidy affect sensitivity to X-irradiation. However, separation of the diploid and tetraploid subpopulations was imperfect. The ratio of diploid to tetraploid cells in the separated and parent (mixed ploidy) lines was therefore monitored at each passage. Tetraploid contamination of the diploid cell subline was undetectable at the time of separation but regrew to 35 per cent by 40 days after separation. Diploid contamination of the tetraploid subline was initially less than 5 per cent and remained quite low until it became undetectable at 74 days. Differences in regrowth of the contaminating subline could not be accounted for by differences in plating efficiency or doubling time, but might result from subpopulation interactions. If so, such phenomena should be considered when using ploidy-dependent cytotoxic treatments.

Cell Line↗
PubMed1988

Separation and characterization of the subunits of the laminin of EHS sarcoma.

A rapid and sensitive method was developed for the preparative separation of laminin subunits. Laminin was extracted and purified from mouse EHS sarcoma. On SDS-PAGE, the reduced and carboxymethylated molecule separated into two components corresponding to molecular weights of about 400 KDa (subunit A) and 200 KDa (subunit B). These two subunits were preparatively separated using heparin-agarose affinity chromatography. The larger subunit quantitatively adhered to the affinity column while the smaller one did not adhere. Amino acid analyses of the separated subunits showed distinct differences. Subunit B was further resolved into two distinct polypeptides of 200 KDa, B1 and B2, by means of reverse-phase HPLC. Although the amino acid compositions of B1 and B2 were very similar, the peptide maps generated by digestion of the B1 and B2 chains with Staphylococcus aureus V8 protease or by cyanogen bromide showed B1 and B2 to differ from each other. Thus, at least three different polypeptide subunits are present in this laminin and probably arise from separate gene origins. These studies provide a basis for the subsequent localization and analysis of the specialized structural and functional domains of laminin.

Animals↗
PubMed1983

Separation of tendon ends after suture of achilles tendon.

Ten patients treated for an acute rupture of the achilles tendon were studied. During the operation a marker was attached to each tendon end. The postoperative separation of the markers was studied by repeated X-ray examinations. Despite immobilization a small initial separation was found during the first 4 days, followed by a period of no separation. After about 20 days a second separation started. No re-ruptures occurred. Both in the rabbit and in man a small initial separation of sutured tendon ends seemed to indicate an adequate tendon suture and therefore also a good tendon healing.

Achilles Tendon↗