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PubMed1986

High yield synthesis of 6-[18F]fluoro-L-dopa by regioselective fluorination of protected L-dopa with [18F]acetylhypofluorite.

Regioselective fluorination of a completely protected phosgene derivative of 3,4-dihydroxy-phenyl-L-alanine (5-(benzyl-3',4'-carbonate)-oxazolidine-2,5-dione) with gaseous 18F-labeled acetylhypofluorite and [18F]F2 in acetonitrile is described. Fluorination with [18F]acetylhypofluorite yields 6-[18F]fluoro-L-dopa with 95% radiochemical purity; fluorination of the same substrate with [18F]F2 yields a mixture of all three structural isomers in a ratio of 70:16:14 for 6-, 5-, and 2-fluoro compounds. Radiochemical yield, relative to [18F] acetylhypofluorite, measured at the end of the synthesis, is (21 +/- 4)% (N = 8). The synthesis requires approximately 40 min (50 min if HPLC was done) and yields the final radiopharmaceutical in a two-step procedure. The specific activity of the final product was approximately 763 mCi/mmol at the end of a 40-min synthesis when 30-min irradiation was used.

Acetates↗
PubMed1987

[Yield and chemical composition of the vegetal parts of the amaranth (Amaranthus hypochondriacus, L.) at different physiological stages].

The genus Amaranthus comprises species which, consumed as vegetables, provide essential nutrients to man; they also have a high acceptability among the population. These two factors justify the need to increase their cultivation. Therefore, the purpose of this research was to establish the most adequate physiological state of maturity, to harvest the leaves for human consumption. The field experiment utilized a randomized block design with three treatments and eight replications. These treatments consisted in harvesting the plants at 25, 40 and 60 days after emergence of the seedlings, samples which served to evaluate: plant height, number of leaves, leaf surface area, gross weight (leaves and stems), net weight (leaves), green matter and dry matter yield, as well as protein. The chemical composition of the harvested material was evaluated also in terms of moisture, protein, crude fiber, ether extract, ash, carbohydrate, calcium, phosphorus, iron, beta-carotene and oxalates. The results obtained in the agronomic study were subjected to analysis of variance for the respective design, with significant differences found between treatments for all the variables studied. In its turn, the results of the chemical analysis were analyzed by a completely randomized design, with significant differences obtained for most of the variables studied, except for ether extract, calcium, iron and oxalates. From the nutritional point of view, the first harvest was the most acceptable due to the chemical composition of the plant, in particular protein (29.5%), beta-carotene (33.7 mg%), calcium (2,356.1 mg%), phosphorus (759.1 mg%) and due to its low crude fiber content, only 11.1 g%. It did not occur so from the agronomic point of view, since during this stage, very low yields of green matter (575.9 kg/ha), dry matter (66.6 kg/ha) and protein (19.7 kg/ha) were obtained. At the second harvest, besides obtaining adequate yields of green matter (6,530.4 kg/ha), dry matter (681.8 kg/ha) and protein 154.3 kg/ha), an acceptable composition in its protein content (22.7 g%), beta-carotene (24.1 mg%), calcium (2,279.8 mg%), phosphorus (740.9 mg%) and iron (52.7 mg%) was also obtained. The crude fiber content, on the other hand, was not excessively increased (14.3 g%), from which findings it was concluded that this is the best stage for harvesting, in comparison with the harvests carried out 25 and 60 days after emergence. Finally, it was observed that harvesting at 60 days gave the highest yields in green matter (24,272.8 kg/ha), dry matter (3,452.0 kg/ha) and protein (510.7 kg/ha).(ABSTRACT TRUNCATED AT 400 WORDS)

Agriculture↗
PubMed1966

Determination of yield pressures: a method for measuring anal sphincter competence.

Resting pressures recorded from the anal sphincter by the open-tip method seem to reflect the last pressure to which the catheter tip was exposed before it entered the sphincter, presumable because sphincter tissues "seal" the recording orifice and thereby "trap" pressure within the recording system. By injecting or infusing small increments of fluid into the system, one can measure a physiologically meaningful pressure--the pressure required to break the "seal." For the resting sphincter, this pressure has been termed the resting yield pressure; for the maximally tightened sphincter, the augmented yield pressure. By determining yield pressures before and during active contraction of the sphincter the involuntary and voluntary components of sphincter function can be separately assessed. Measurement of yield pressures can separate sphincters judged competent or incompetent on clinical grounds. Injection of microliter quantities of fluid into the recording catheter whose tip is in the sphincter causes a marked rise in pressure. Although "bleeders" or constant slow infusions of fluid do not affect pressures recorded from within a cavity, they do significantly alter pressures recorded from a sphincter zone.

Anal Canal↗
PubMed1976

Improving the specificity and yield of the contagious bovine pleuropneumonia complement fixation test antigen.

Several methods for increasing yield and specificity of the contagious bovine pleuropneumonia complement fixation test antigen which is derived from Mycoplasma mycoides subsp mycoides, strain V5, were examined. Changes in culture conditions that increased the cell mass per unit volume of culture did not result in comparable increase in antigen yield. Sixteen to 60-day-old cultures yielded more boiled cell antigen than younger cultures. Some antigen in young cultures appeared to be masked, probably by galactan. The yield of antigen extracted from boiled cells with ethonol was as much for two to eight-day-old cultures as for older cultures. The ethanol extract antigen was less reactive with false positive bovine sera than standard boiled antigen while reactivity with anti Mycoplasma mycoides sera was similar to that of standard antigen. Adsorbed gamma globulin was not detected in either boiled or ethanol extract antigen. The data suggest that several complement fixing antigens were present in antigens derived from older cultures.

Animals↗
PubMed1977

[A long-term experiment on the complex influence of cultivating, fertilizing, and crop rotation measures on humic substances in soil and development of yield (author's transl)].

In a 10-year field experiment, the influence of fertilizing, cultivating, and crop rotation measures on the C-content of the soil, humus quality of the organic soil substance, and the yield was investigated. With cultivation of fodder plants only, the C-content of the soil can be improved by increased mineral and increased organo-mineral fertilization at any depth of cultivation. When in the same location there was a turn between cereals and green crops, a decrease of C-rate can only be prevented by increased organo-mineral fertilization. Continuous cultivation of root crops resulted in a decrease of the C-content. Deeper tillage of the soil generally decreased C-content. Within the years, a variability of the pure humin substances could be detected, depending on the rotation of crops and C-content. The composition of the fulvic acids is differentiated in dependence on the factors "time" and "cultivation". The effect of fertilization variants on the yield was different. Fertilization in that location with manure only, compared with mineral fertilization, caused in most cases depression in yield. Decrease on yield by deeper ploughing had the least influence with root crops.

Agriculture↗
PubMed1984

The quality-costs of an analytical process: 2. A test yield formulation of the predictive value quality-costs model.

A quality-costs model has been developed to predict the cost effectiveness of a batch analytical process subject to intermittent analytical errors. The process test yield (the proportion of analytical measurements in an analytical run that are reportable as patient test results) provides a useful measure of the efficiency of an analytical process and can be related to critical characteristics of the measurement and control procedures. Equations are provided to estimate test yield from the measurement procedure's frequency of medically important errors (f) and the control procedure's probabilities for error detection (ped) and false rejection (pfr). Examples illustrate how losses in process output depend on the characteristics of the measurement and control procedures, and how increased control efforts may actually improve the yield of analytical processes when the frequency of errors is high. The test yield formulation of the quality-costs model should aid efforts to provide more cost effective analytical processes.

Chemistry, Clinical↗
PubMed1983

Platelet function, size and yield in whole blood and in platelet-rich plasma prepared using differing centrifugation force and time in domestic and food-producing animals.

The effects of centrifugation force and time upon platelets function, mean platelet volume and platelet yield were compared with whole blood platelet counts and size in citrated blood samples from the bovine, canine, caprine, equine, feline, ovine and porcine species. The results were similar, for a given species, irregardless of sample volume. Bovine, caprine, feline and ovine platelet yields and mean platelet volumes were maximal when platelet-rich plasma was prepared using longer centrifugation times and lower gravitational forces. Canine, equine and porcine platelet yields and mean platelet volumes were maximal when platelet-rich plasma was prepared using shorter centrifugation times and higher gravitational forces. Platelet aggregation to adenosine diphosphate or arachidonic acid was not effected by the method of platelet-rich plasma preparation in bovine, caprine, feline, ovine or porcine platelets. Equine platelet aggregation was maximal when platelet-rich plasma was prepared using longer centrifugation times and lower gravitational forces. Canine platelet aggregation, particularly arachidonic acid-induced aggregation, was maximal when platelet-rich plasma was prepared using short centrifugation times and higher gravitational forces. It appeared that the effects of centrifugation parameters upon platelet yield depended upon the relative difference between platelet and red blood cell volumes.

Animals↗
PubMed1984

Increased yields of exchanges but not of deletions in X-irradiated human peripheral lymphocytes following phytohemagglutinin stimulation.

We have irradiated human peripheral lymphocytes after various intervals of phytohemagglutin stimulation to determine the time course for exchange induction and to determine whether or not deletion yields increase with increasing intervals of stimulation. We found no increase in deletion yields for intervals up to 12 hr, and rings and dicentric yields increased by about 60% in the interval between 0 and 6 hr but then reached a plateau. We also measured induced unscheduled DNA synthesis during the same interval and found it generally increased during the first 6 hr like exchange yields, but then tended to decrease again.

Chromosome Aberrations↗
PubMed1982

[Photobleaching quantum yields of visual pigments in the "fauve de Bourgogne" and "albino" rabbit (author's transl)].

Photobleaching quantum yields of visual pigments extracted from retinas of the "fauve de bourgogne" and "albino" rabbit were measured in monochromatic light. For the "fauve de Bourgogne" rabbit, the photobleaching quantum yield was to be 0.65 at different excitation wavelengths (546, 491.6 and 436 nm); at shorter wavelengths, this quantum yield was lower ie. 0.36 at 405 nm. This wavelength effect has been observed on visual pigments extracted from bees retina. In contrast, in the "albino" rabbit, the photobleaching quantum yield was constant and equal to 0.31 whatever the excitation wavelength between 546 and 405 mn.

Animals↗
PubMed1982

[Ratio between lactating and dry periods in cows differing in milk yield and duration of the period between calving].

A study was carried out on the duration of the lactation period at different milk yield values and variable duration of the calving interval. It was found that the time period of lactation was influenced by the calving interval and the amounts of milk obtained. When the calving period was more than 365 days there was an unproportional lengthening of the lactation period which led to the respective lengthening of the dry period of cows. One day lengthening of the calving period brought about an increase of the dry period by 0.3 to 0.4 days. In the groups where milk yields amounted up to 4000 1 per cow the relative share of animals whose lactation period was below the standard was higher as compared to the groups with milk yields amounting over 4000 1 per cow. The higher the milk yield the higher the number of cows whose lactation period was within the norm. However, what is commonly observed is that with most of the cows the lactation period is below the standard, and this substantiates the fact that considerable amounts of milk are not really obtained.

Animals↗
PubMed1980

A critical review of platelet yield by Haemonetics 30 . Based on literature and own observations.

By means of a haemonetics 30 cell separator platelets were collected for transfusion purposes from 18 different blood donors. A median yield of 5.7 X 10(11) platelets was obtained. The yield of platelets was found to be linearly related to the donors' initial platelet counts. The procedures were standardized by using one size of bowl (225 ml), performing 10 cycles per procedure, and performing all cycles as uniformly as possible. The median time per procedure was 118 min. Mild donor reactions were seen in 8 donors (44%) consisting of circumoral tingling. The decrement in the donors' platelet count was 86 X 10(9)/1, 37% of the initial platelet counts. The choice of the bowl size of 225 ml is motivated. The absurdity of the expression of yield pe h of processing, and of yield per 1 of blood processed is discussed. Furthermore, it is shown, that neither the fall in haematocrit nor the fall in the platelet count during the procedure are linear. The formulas commonly used for calculating the blood volume and platelet extraction efficiency, which are based on these assumptions, cannot therefore, in our opinion, be used.

Blood Donors↗
PubMed1978

Development of a practical oral dexamethasone premedication schedule leading to improved granulocyte yields with the continuous-flow centrifugal blood cell separator.

Studies were conducted to improve the yield of granulocytes collected for transfusion from normal donors by means of the continuous-flow centrifugal blood cell separator. Nonleukapheresed donors were medicated with varying schedules of corticosteroids to learn the magnitude and duration of granulocytosis. Normal donors were medicated with varying schedules of corticosteroids prior to a 4-hr leukapheresis and the granulocyte yields determined. It was found that maximum yields (32.2 x 10(9) granulocytes) were obtained by use of dexamethasone given orally 12 and 3 hr prior to leukapheresis. There was a good correlation between the yields and the circulating granulocyte count at the start and during the procedure.

Administration, Oral↗
PubMed1994

Yield of single-strand breaks due to attack on DNA by scavenger-derived radicals.

We have measured the yield of single-strand breaks (SSBs) in plasmid DNA after 137Cs gamma irradiation, in the presence of dimethyl sulfoxide (DMSO). In the presence of oxygen, the formation of SSBs is due to hydroxyl radical attack. As the DMSO concentration is increased from 10(-4) mol dm-3 to 1 mol dm-3, the SSB yield in the presence and absence of oxygen decreases by over 100-fold and less than 10-fold, respectively. From the DMSO and DNA concentration dependencies of the SSB yield in the absence of oxygen, the second-order rate constant for the reaction of the methyl radical (derived from DMSO) and DNA can be estimated as k2 = 8.8 x 10(4) dm3 mol-1 s-1. Several other scavengers were compared with DMSO under anoxia. Radicals derived from isopropyl alcohol and glycerol also caused SSB formation in DNA, while those from 2-deoxyribose, thymine, 1,3-dimethylthymine and 1,3-dimethyluracil did not. In the case of the scavenger tert-butyl alcohol, it is unclear whether the hydrogen atom (H.) or an organic radical is responsible for the higher SSB yield under anoxic conditions.

DNA Damage↗
PubMed1994

[Isolation and separation of human adult hepatocytes from resected liver: cellular yield and purity using different methods].

Cultivated human hepatocytes (HC) for in vitro cell culture models are not frequently used yet. Besides, there are still several different methods of isolation, separation and cultivation of HC in use. We compared various methods to obtain isolated HC. Cell yield as well as high purity of the HC cultures were the main objectives of this study. For isolation, best results were made with a modified 2-step perfusion method. The methods of disintegration having a stronger mechanical component (i.e. disintegration of tissue in a magnetic stirrer) yielded only few vital cells. To separate HC from non-parenchymal cells (NPC) after isolation we tested two methods. Best results could be reached by centrifugation in Percoll adjusted to a density of 1.065 g/ml for 10 min. at 50xg. Thus, we were able to obtain nearly pure HC suspensions having viabilities ranging between 74 and 100%. Contamination with NPC was lower than 1% as assessed by immunocytochemistry. In contrast, only lower yield and purity resulted by application of a 3-times centrifugation at 28xg for 5 minutes. For cultivation of HC, both initial adherence and survival was superior when collagen type I coated culture plates were used instead of uncoated plates. Up to now, a maximum yield of 2.14 x 10(7) viable HC per gram processed tissue and a maximum culture period of 6 weeks was reached.

Adult↗
PubMed1993

Comparative cytologic yield and quality of three Pap smear instruments.

BACKGROUND: Various sampling techniques of the cervix have established false negative rates ranging from 18% to 45%. A number of studies suggest that this false negative rate can be reduced by sampling techniques that are associated with higher yields of endocervical cells. METHOD: This study enrolled 301 women, each of whom had a Pap smear obtained using three different sampling instruments (a cervical brush, a plastic spatula, and a cotton swab) in random order. RESULTS: The cervical brush yielded a better endocervical sample than either of the other instruments (P < .001), and there was no difference between the swab and spatula. In addition, the recovery of endocervical cells increased with each additional sample taken, regardless of instrument used (P < .001), although the difference in yield between the second and third samples was not significant. CONCLUSIONS: To enhance the yield of endocervical cells in Pap smear sampling, consideration should be given to using the cervical brush routinely as a sampling instrument and to taking more than one sample per screening.

Adolescent↗
PubMed1993

Hypertonic treatment does not affect the radiation yield of interphase chromosome breaks in DNA double-strand break repair-deficient xrs-5 cells.

A DNA double-strand break (DSB) repair-deficient CHO cell line, xrs-5, was used to evaluate the effect of hypertonic treatment on the radiation yield of interphase chromosome breaks, as visualized by means of premature chromosome condensation (PCC). For this purpose, interphase chromosome breaks were measured in plateau-phase G1 cells after exposure to 10 Gy X rays using either the standard protocol for PCC induction or a revised protocol that includes a brief (20 min) treatment in hypertonic medium (500 mM NaCl) during chromosome condensation. Experiments at the chromosome level were complemented by experiments at the DNA and the cellular level performed under similar postirradiation conditions. The results obtained were compared to those reported previously for CHO cells. Radiation yields of interphase chromosome breaks, as measured using standard protocols for PCC induction, were higher in xrs-5 than in CHO cells. However, the yields became similar between the two cell lines when a 20-min incubation in hypertonic medium was introduced immediately after fusion with mitotic cells. This equalization was due to the fact that incubation in hypertonic medium did not affect the radiation yield of interphase chromosome breaks in xrs-5 cells but increased it in CHO cells to levels similar to those measured in xrs-5 cells. This result suggests that xrs-5 cells constitutively express as interphase chromosome breaks a subset of DSBs which in repair-proficient CHO cells requires incubation in hypertonic medium for transformation to interphase chromosome breaks. Rejoining of DSBs, when measured in isotonic medium, was incomplete in xrs-5 cells compared to CHO cells. Rejoining of DSBs normally repaired in xrs-5 cells was completely inhibited during treatment in hypertonic medium. Postirradiation treatment in hypertonic medium affected the survival of xrs-5 cells only modestly, suggesting that the sector of PLD (beta-PLD) which required treatment in hypertonic medium for fixation in repair-proficient CHO cells is fixed constitutively in xrs-5 cells. These results are in agreement with a model developed to interpret results obtained in similar experiments with CHO cells (Iliakis et al., Radiat. Res 135, 160-170, 1993). The model postulates that potentiation in CHO cell killing induced by hypertonic treatment is caused by the transformation of a subset of fast-repairing DSBs to irreparable interphase chromosome breaks and assumes that this transformation is equivalent to fixation of beta-PLD.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

A method for the preparation of DNA from calf thymus nuclei in maximum purity and yield, analysis of this DNA compared with that obtained by other methods.

In the preparation of calf thymus DNA, a method (1) was developed to yield DNA in maximum yield and purity, with a minimum of shear degradation, which differed in three respects from those used in standard preparations: 1) use of calf thymus nuclei rather than whole tissue as a source of the DNA; 2) use of initial Pronase, then on the next cycle RNAase + Pronase digestions; 3) use of optimal concentrations of reagents to precipitate denatured proteins in the purification cycles. The optimal reagent concentrations were determined in tests by changing each variable one at a time to be 3M NaCl, 3% sarcosyl. The purification cycles consisted of adjustment of DNA solution in buffer to 3M NaCl-3% sarcosyl, centrifugation, alcohol precipitation, and redissolving DNA fibers in buffer. The DNA from nuclei, digested with Pronase then with RNAase + Pronase was then subjected to five additional purification cycles. The purified DNA thus obtained (N-DNA) had a protein content of 0.64%. When purified calf thymus nuclei are subjected directly to salt-sarcosyl purification cycles, the initial protein content is about 21%, but after the second cycle the percentages of protein fell off in subsequent cycles in a parallel manner as compared to the DNA obtained by the Blin and Stafford method (2) and then subjected to NaCl-sarcosyl purification. The degree of purity obtained by these purification methods was appreciably greater than obtained for a modified method of Gross-Bellard et al. (3). Two portions of DNA purified by this method were analyzed: 1) dialyzed 11 times after the Proteinase K digestion, and 2) dialyzed 6 times. Portion 1) gave a protein content of 0.96% and a yield of 0.135% (g/100 g tissue). Portion 2) gave a protein content of 1.34% and a yield of 0.133%.

Animals↗
PubMed1993

Effects of blood storage time and temperature on DNA yield and quality.

Whole blood is a common source of DNA, especially for genotype diagnostic services. Many laboratories now receive blood samples by mail and/or store blood samples prior to DNA extraction. Therefore, the effects of storage time (number of days from blood collection to DNA extraction) and temperature on DNA yield and quality are important. We compared DNA yield and quality from bovine blood samples exposed to one of sixteen treatment combinations of storage time (3, 7, 14 or 28 days) and temperature (-20 degrees, 4 degrees, 23 degrees or 37 degrees C) to the results obtained when DNA was extracted within 4 h of collection. The highest mean DNA yields, relative to the control samples, were obtained from blood stored at 4 degrees C. Blood stored at 37 degrees C for > or = 3 days or 23 degrees C for > or = 7 days yielded less (P < .05) DNA, compared with blood stored at 4 degrees or -20 degrees C for up to 28 days. DNA was not recovered from three of the samples stored at 23 degrees C and five of the samples stored at 37 degrees C. The genomic DNA obtained was of high molecular weight and suitable for restriction enzyme digestion and PCR amplification, regardless of the treatment.

Animals↗