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PubMed1994

The ASTROCULTURE(TM) flight experiment series, validating technologies for growing plants in space.

A flight experiment, ASTROCULTURE(TM)-1 (ASC-1), to evaluate the operational characteristics and hardware performance of a porous tube nutrient delivery system (PTNDS) was flown on STS-50 as part of the U.S. Microgravity Laboratory-1 mission, 25 June to 9 July, 1992. This experiment is the first in a series of planned ASTROCULTURE(TM) flights to validate the performance of subsystems required to grow plants in microgravity environments. Results indicated that the PTNDS was capable of supplying water and nutrients to plants in microgravity and that its performance was similar in microgravity to that in 1g on Earth. The data demonstrated that water transfer rates through a rooting matrix are a function of pore size of the tubes, the degree of negative pressure on the 'supply' fluid, and the pressure differential between the 'supply' and 'recovery' fluid loops. A slightly greater transfer rate was seen in microgravity than in 1g, but differences were likely related to the presence of hydrostatic pressure effects at 1g. Thus, this system can be used to support plant growth in microgravity or in partial gravity as on a lunar or Mars base. Additional subsystems to be evaluated in the ASTROCULTURE(TM) flight series of experiments include lighting, humidity control and condensate recovery, temperature control, nutrient composition control, CO2 and O2 control, and gaseous contaminant control.

Capillary Action↗
PubMed1994

Peculiarities of moisture transfer in capillary-porous soil substitutes during space flight.

Aboard the orbital stations, "Salyut-7" and "Mir", investigations on the peculiarities of moisture transfer in capillary-porous bodies (CPB; that is, soil substitutes) in microgravity were conducted by the authors with a specially designed device and an original method. Water distribution in CPB-perlite (fractions 1.5... 2.5 mm) was studied, and theoretical dependances for linear capillary impregnation of CPB were determined.

Aluminum Oxide↗
PubMed1994

Porous Tube Plant Nutrient Delivery System development: a device for nutrient delivery in microgravity.

The Porous Tube Plant Nutrient Delivery System or PTPNDS (U.S. Patent #4,926,585) has been under development for the past six years with the goal of providing a means for culturing plants in microgravity, specifically providing water and nutrients to the roots. Direct applications of the PTPNDS include plant space biology investigations on the Space Shuttle and plant research for life support in Space Station Freedom. In the past, we investigated various configurations, the suitability of different porous materials, and the effects of pressure and pore size on plant growth. Current work is focused on characterizing the physical operation of the system, examining the effects of solution aeration, and developing prototype configurations for the Plant Growth Unit (PGU), the flight system for the Shuttle mid-deck. Future developments will involve testing on KC-135 parabolic flights, the design of flight hardware and testing aboard the Space Shuttle.

Capillary Action↗
PubMed1996

Capillary movement of liquid in granular beds in microgravity.

A more complete understanding of the dynamics of capillary flow through an unsaturated porous medium would be useful for the development of an effective water and nutrient delivery system for the growth of plants in space. An experiment was conducted on the Mir Space Station that used an experimental cuvette called "Capillary Test Bed" to compare fluid migration under terrestrial laboratory conditions by positioning the cuvette such that the hydrostatic force is negated and on Mir under microgravity conditions. Differences in fluid migration in the cuvette were observed with migration being slower in microgravity compared with some ground control experiments.

Capillary Action↗
PubMed1985

Capillarity and oxygen diffusion distances of the soleus muscle of guinea pigs and rats. Effects of hyperthyroidism.

The relationship between capillarity and oxidative capacity in the soleus muscle of rats and guinea pigs injected with triiodothyronine (T3) or with saline for up to 4 weeks was studied. The rats' soleus weight and FCSA were not affected by T3, but the guinea pigs that received T3 had smaller muscle weight and FCSA than the controls. The activities of cytochrome c oxidase and citrate synthase were significantly (41 and 65%) higher in the T3 than in the control rats. T3 administration did not affect the activities of these enzymes in the soleus of the guinea pigs. Capillary density (CD) was higher in T3 rats (892 +/- 80 vs 622 +/- 54 caps/mm2), and in T3 guinea pigs (1219 +/- 95 vs 739 +/- 142 caps/mm2). The higher CD in T3 rats was due to growth of new microvessels, while in the T3 guinea pigs it was due to a reduction in FCSA. Mean and maximal diffusion distances evaluated by the closest individual method were reduced by 2.02 and 3.37 microns in rats, and by 3.73 and 6.16 microns in guinea pigs. The magnitude of the reduction in diffusion distances brought about by the increased capillary density was partially offset by a concomitant change in the capillary arrangement from an ordered (hexagonal), towards a random distribution. These results seem to indicate that skeletal muscle capillarity is not necessarily determined by the oxidative capacity of the fibers.

Adenosine Triphosphate↗
PubMed1984

Rat anterior pituitary cells maintained on artificial capillaries: responses of thyrotrophs and lactotrophs to depolarization, TRH and dopamine.

Rat anterior pituitary cells have been maintained over an 18-day period in a perfusion system designed around artificial capillaries. Using novel methodology the cells have been visualized by light microscopy and appear as aggregates, closely attached to and sometimes stretching around the capillaries. Their morphology is consistent with previous histology at the level of light microscopy. The techniques described are compatible with immunohistochemistry and electron microscopy. The functional integrity of thyrotrophs and lactotrophs maintained in the system has been examined by measuring the dynamics of TSH and PRL secretion in response to depolarization, TRH and dopamine (DA). TSH and PRL were significantly and reproducibly released by TRH over a 7-day period. On each day the release was dose-dependent with a threshold of at least 28 pg. Qualitatively the responses were rapid in onset (within minutes) for both hormones. Similar responses were measured in response to high K+ depolarization. Basal secretion of TSH and PRL was rapidly and significantly inhibited by DA in a dose-dependent manner (ED50 20 +/- 25 nM for TSH and 70 +/- 40 nM for PRL). Inhibition was dependent on the continued presence of DA and could be mimicked by bromocriptine and stereospecifically prevented by the active but not the inactive isomer of the DA receptor antagonist butaclamol. Simultaneous administration of 10(-6) M DA with 10(-8) M TRH prevented the release of TSH and PRL. The effect of DA was transient, subsequent TRH responses being qualitatively and quantitatively normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Receptors for angiotensins I and II: their relevance to renal haemodynamics, blood pressure control and hind-limb blood flow.

The well established differential pulmonary handling of angiotensins I and II indicates the possibility that vascular receptors for the deca- and octa-peptides do not necessarily involve common sites in the renal vasculature either. Experimental findings involving haemodynamic changes within the kidney in anaesthetised and conscious sheep, with utilization of the angiotensins, and also of noradrenaline, are briefly presented; the implications of the intra-renal water and creatinine transfers are discussed, especially as they concern the possible location of angiotensin receptors in the renal blood vessels. Other aspects of the relationships between the peptides are also taken into account particularly with regard to a postulated angiotensin I [NaCl] dependent peritubular capillary antidiuretic action, angiotensin converting enzyme inhibition, Goldblatt clamp induced hypertension and blood flow through the hind-limbs.

Angiotensin I↗
PubMed1991

Capillary zone electrophoresis: its applicability and potential in biochemical analysis.

Recent developments in capillary zone electrophoresis (CZE) are reviewed, starting with available instrumentation, a description of different operational modes and the most commonly used detection systems. Appropriate attention is paid to CZE-mass spectrometry coupling and coupling of electrophoretic and chromatographic procedures. The possibility of separating chiral molecules is also discussed. Examples of applications concern mainly amino acids, peptides, proteins, nucleic acids and their constituents.

Amino Acid Sequence↗
PubMed1991

Application of capillary isotachophoresis in peptide analysis.

This paper gives a broad and detailed review of the applications of one of the modern high-performance electromigration separation techniques--capillary isotachophoresis (ITP)--in peptide analysis. Examples are presented of the utilization of capillary ITP for peptide analysis in the fields of chemistry, general and clinical biochemistry, biology, biotechnology, pharmacy and the food industry. The complete composition of all the electrolyte systems used for peptide ITP analyses in both cationic and anionic techniques is given in tabular form. According to the purpose of analysis the applications are divided into several sections: model studies, determination of physico-chemical characteristics, purity control of both intermediate and final peptide preparations, including the determination of low-molecular-mass ionogenic admixtures, and the analysis of peptides in biological fluids and tissue extracts. In addition to the main applications the theoretical and methodological aspects of peptide ITP analysis are discussed. The basic electromigration properties of peptides (their polyampholyte character, effective and absolute mobilities, acid-base equilibria) are explained and the selection of parameters for peptide ITP analysis is described in detail. The advantages and disadvantages of ITP compared with other electrophoretic and chromatographic methods used for peptide analysis are discussed.

Amino Acid Sequence↗
PubMed1993

Detection of point mutations in DNA using capillary electrophoresis in a polymer network.

The use of capillary electrophoresis (CE) in a polymer network for single-strand conformation polymorphism (SSCP) is investigated. SSCP is a method to detect DNA point mutations, essential in the diagnosis of several diseases. The PCR (polymerase chain reaction) amplified p53 gene, a tumour suppressor gene known to be frequently mutated in malignant cells, was subjected to CE analysis. Two single-strand DNA fragments of 372 bp in length differing in only one nucleotide could be separated. We conclude that SSCP using CE in a polymer network is a powerful method for the detection of point mutations in DNA sequences.

Base Sequence↗
PubMed1993

Investigation of the metabolic fate of the neuroleptic drug haloperidol by capillary electrophoresis-electrospray ionization mass spectrometry.

Combined capillary electrophoresis-mass spectrometry (CE-MS) is a powerful analytical tool for the characterization of components of complex mixtures. Furthermore, when interfaced with an electrospray ionization (ESI) source, skimmer induced fragmentation can yield structural information that aids compound identification. We show that these techniques can be used to probe the metabolic fate of drugs by investigation of the phase I metabolism of the widely used neuroleptic drug haloperidol. In addition, we demonstrate differences of in vitro metabolism of haloperidol by mouse and guinea pig hepatic microsomes.

Animals↗
PubMed1994

Determination of acenocoumarol in human plasma by capillary gas chromatography with mass-selective detection.

A method for the determination of acenocoumarol in human plasma by capillary gas chromatography-mass-selective detection is described. After addition of a structurally related analogue as the internal standard, the compounds are extracted from plasma at acidic pH into toluene, back-extracted with a basic solution and re-extracted from hydrochloric acid solution with toluene, which is then evaporated to dryness. The compounds are converted into their methyl derivatives, which are determined by gas chromatography using a mass-selective detector at m/z 324 for acenocoumarol and m/z 338 for the internal standard. The reproducibility and accuracy of the method were found to be suitable over the acenocoumarol concentrations range 2.2-74 nmol/l. The method could be considered as selective for acenocoumarol in the presence of its major metabolites in plasma.

Acenocoumarol↗
PubMed1994

Stereoselective determination of verapamil and norverapamil by capillary electrophoresis.

An analytical method has been developed to determine simultaneously the verapamil and norverapamil enantiomers in human plasma using capillary electrophoresis. Among the cyclodextrins tested as chiral selector, only trimethyl-beta-cyclodextrin was suitable to resolve the four enantiomers. The analysis was achieved in less than 10 min. Selectivity, linearity, precision and accuracy were evaluated before the chiral method was successfully implemented for routine use to simultaneously determine the four enantiomers in several thousands of human plasma samples. The robustness of the capillary electrophoretic method and its suitability were demonstrated by the coefficients of variation which were lower than 11%, even at the limit of quantification (2.5 ng/ml), for the analysis of more than one hundred quality control samples.

Capillary Action↗
PubMed1994

Determination of fosfomycin in biological fluids by capillary electrophoresis.

A capillary electrophoresis method was developed for the determination of the antibiotic fosfomycin in serum, cerebrospinal fluid and aqueous humor. The technique uses indirect UV detection and the working buffer includes an organic cation to improve fosfomycin mobility. The electrophoretic time of migration is less than 7 min in both fluids. The limit of quantification is 2.5 and 1 microgram/ml in serum and aqueous fluids, respectively (signal-to-noise ratio = 3). The method was validated in serum and water over the concentration range 2.5-200 micrograms/ml. The calibration graph for serum was linear with a correlation coefficient r = 0.999. At a fosfomycin concentration of 2.5 micrograms/ml in serum, the intra- and inter-day precisions (coefficients of variation) were 5 and 5.2%, respectively. The mean recovery in serum was 94.5% (S.D. = 2.4%).

Aqueous Humor↗
PubMed1994

Assay of zatebradine in plasma by fully automated sample clean-up, capillary gas chromatography and ammonia chemical ionisation mass spectrometry.

A method has been developed for the measurement of zatebradine (UL-FS 49), a heart-rate lowering drug, suitable for the treatment of stable angina pectoris. The method comprises a fully automated liquid-solid extraction using a Zymark Benchmate, a capillary gas chromatography and ammonia chemical ionisation (CI) mass spectrometry using hexadeuterated zatebradine for the internal standard. The assay has a mean between-batch imprecision of 4.9% and a mean inaccuracy of 1.5%. The calibration curve covers the range of 1-30 ng/ml. About 60 samples can be handled per day. The assay has been successfully applied to human pharmacokinetic studies.

Ammonia↗
PubMed1995

Simultaneous measurement of phytosterols (campesterol and beta-sitosterol) and 7-ketocholesterol in human lipoproteins by capillary column gas chromatography.

7-Ketocholesterol (a major cholesterol oxidation product) and phytosterols are important indicators of lipoprotein oxidation and lipoprotein metabolism respectively. We describe a simple, sensitive and reproducible method for the simultaneous measurement of these sterols in human lipoprotein samples by capillary column gas liquid chromatography. The method is suitable for clinical studies as small quantities of lipoprotein are required. Sterols are analysed after extraction from lipoprotein samples obtained by sequential flotation ultracentrifugation. The method involves briefly: extraction from lipoprotein samples using chloroform-methanol, saponification of sterol esters using cold potassium hydroxide, purification and derivatisation to trimethylsilyl ethers using BSTFA and 1% TMCS. Oxidation is prevented by drying under nitrogen and the use of powerful antioxidants. Separation is achieved using a DB-1 capillary column and a two-stage temperature ramp from 180-250 degrees C and detection using FID. The identity of sterols can be confirmed by GC-MS. Phytosterols and 7-ketocholesterol are present at low concentration in all the major lipoproteins. Using [3,4-13C]cholesterol and GC-MS we present evidence that cholesterol oxidation does not occur during the processing of lipoproteins using this technique.

Capillary Action↗
PubMed1995

Determination of xanomeline (LY246708 tartrate), an investigational agent for the treatment of Alzheimer's disease, in rat and monkey plasma by capillary gas chromatography with nitrogen-phosphorus detection.

A GC method is described for the determination of xanomeline (LY246708 tartrate) and selected metabolites in rat and monkey plasma. The analytes, including an internal standard, were extracted from plasma at basic pH with hexane. The organic extract was evaporated to dryness and the residue was reconstituted in hexane. The analytes were separated from metabolites and endogenous substances using a DB1701 capillary column. The analytes were detected using nitrogen-phosphorus detection (NPD). The limit of quantitation was determined to be 8 ng/ml, and the response was linear from 8 to 800 ng/ml. The method has been successfully applied to rat and monkey samples pursuant to the development of xanomeline as an agent for the symptomatic treatment of Alzheimer's disease.

Alzheimer Disease↗
PubMed1994

High-performance liquid chromatography and capillary electrophoresis of L- and D-carnitine by precolumn diastereomeric derivatization.

A new method for the simultaneous assay of D- and L-enantiomers of carnitine is described. The method is based on precolumn derivatization with (+)-1-(9-fluorenyl)ethyl chloroformate [(+)FLEC] producing a diastereomeric derivative which can be detected both by UV absorbance and fluorescence detection. Also acyl esters of carnitine can be processed with this method, after alkaline hydrolysis. The D-enantiomer of carnitine and acylcarnitine can be detected at a concentration as low as 0.2% in the raw material and in pharmaceuticals. Assays can be carried out using an autoinjector either by HPLC or capillary electrophoresis (CE) because the derivative proved to be very stable. Its application is proposed for the routine assay of the enantiomeric excess of L-carnitine and their acyl esters in pharmaceutical products.

Acylation↗