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At least 487 records · Page 27Linked to original sources
PubMed2000

Trimethylsilyl- and trimethylstannyldimethylphosphane--convenient and versatile reagents for the synthesis of polyfluoroaryldimethylphosphanes.

Trimethylsilyldimethylphosphane (Me3SiPMe2) and the corresponding tin compound (Me3SnPMe2) were used as reagents for the substitution of fluorine by the Me2P group in polyfluoroarenes C6F5X (X = F, H, Cl, CF3) and C5NF5. The reactions occur even under mild conditions (T = 0-20 C), either in benzene or without solvent, to give as a rule 4-X-1-(dimethylphosphano)tetrafluorobenzenes (XC6F4PMe2, 1-4) and 4-(dimethylphosphano)tetrafluoropyridine (C5NF4PMe2, 5), respectively, in yields between 75 and 95%. In the case of C6F6, double substitution is also observed, which affords 1,4-bis(dimethylphosphano)tetrafluorobenzene (6). A very efficient route to the compounds XC6F4PMe2 (X = F, H, Cl, CF3) and C5NF4PMe2 was developed as a one-pot reaction of the corresponding fluoroarenes with tetramethyldiphosphane (P2Me4) and trimethyltin hydride (Me3SnH) at moderate temperatures. This process was tested for C6F6 and perfluorobiphenyl which gave C6F5PMe2 (1) and 4,4'-bis(dimethylphosphano)octafluorobiphenyl (7), respectively. The results, which included kinetic measurements that used the intensities of the 31P signals, revealed the influence of the substrate type on the rate of reaction in the sequence: C5NF5>C6F5CF3> C6F5Cl, C6F5PMe2>C6F5H>C6F6>> C6H5F. Ab initio calculations were carried out on the model reactions of pentafluoropyridine with silylphosphane, phosphane or phosphide to discriminate between possible reaction mechanisms. The novel phosphanes were characterised by spectroscopic investigations (NMR, MS), by preparation of the related thiophosphanes ArFP(=S)Me2 (8-14), their spectroscopic and analytic data and single crystal X-ray diffraction studies on five of these derivatives.

Journal Article↗
PubMed1990

Visualization of sulfur-containing components associated with proliferating chondrocytes from rat epiphyseal growth plate cartilage: possible proteoglycan and collagen co-migration.

Electron microscopy of epiphyseal growth plate cartilage from normal 4-5-week-old rats has revealed extensive fibrillar aggregates and globules in the pericellular spaces of proliferating chondrocytes. These cells contained small globules and diffusely coiled, fine filaments located within large, membrane-invested vacuoles. All such structures were observed after a variety of different tissue fixation regimes, including glutaraldehyde, osmium tetroxide, and potassium pyroantimonate. The fibrillar aggregates and globules were often overlapping and intermeshed and extended to 0.5 micron in length from their point of origin at cell membranes. Vacuoles were usually found at the periphery of cells, and some, by membrane fusion with the cell envelope, appeared contiguous with extracellular spaces wherein their contents could be discharged. Fine filaments and globules were occasionally observed in the Golgi complex and cisternae of endoplasmic reticulum of the chondrocytes. Further characterization of the cellular and pericellular components by electron microscopic radioautography, electron probe microanalysis, and electron spectroscopic imaging indicated the presence of sulfur, a result suggesting these aggregates, filaments, and globules in part represent proteoglycans in various stages of synthesis, secretion, and assembly. Additional radioautography utilizing 3H-proline implied that filament bundles are also composed of collagen, a result posing the possibility that this protein and the putative proteoglycans may co-migrate both intracellularly and within pericellular matrices. In extracellular matrices adjacent to cell lacunae, the fibrillar aggregates appeared in close association with typical collagen type II fibrils, an observation providing evidence for proteoglycan-collagen network formation in this region of the rat epiphysis. These microscopic and analytical data in situ would support certain studies in vitro of proteoglycan-collagen type II and IX association and are important in describing the interaction of such cartilage components ultimately involved in matrix formation.

Animals↗
PubMed1995

Some analogues of 1,4-disubstituted piperazines as hypnotic and sedative agents.

Preparation, analytical data, and biological properties such as acute toxicity, influence on spontaneous and amphetamine induced locomotor activity, hypnotic activity, influence on hexobarbital narcosis and anticonvulsant activity of new analogues of pyrimidyl piperazines--ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]-3-oxopropanoate (4), 1-[4-(2-pyrimidyl)-1-piperazinyl]-1,3-butandione (5), ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]butanoate (6) and 1-[4-(2-pyrimidyl)-1-piperazinyl]-2-acetyl-1-hexanone (7)--are reported.

Amphetamine↗
PubMed2004

The synthesis and anticonvulsant activity of some omega-phthalimido-N-phenylacetamide and propionamide derivatives.

In this study, by combining anilide and N', N'-phthaloylglycinamide pharmacophores which are known to produce potent anticonvulsant compounds, sixteen omega-phthalimido-N-phenylacetamide and propionamide derivatives bearing substituents at positions 2 or 2, 6 on N-phenyl ring have been synthesized. The structural confirmation of the title compounds was achieved by interpretation of spectral and analytical data. The anticonvulsant activity of the title compounds was determined against maximal electroshock seizure at 100 mg/kg dose level in mice. The preliminary screening results indicated that omega-phthalimido-N-phenylacetamide and propionamide nuclei have pronounced anticonvulsant activity against maximal electroshock seizure.

Acetamides↗
PubMed1990

Magnetic resonance imaging: calculation of rates of energy absorption by a human-torso model.

The three-dimensional impedance method was used to estimate specific absorption rate (SAR) in a human-torso model during exposure to the time-varying and static magnetic fields used in magnetic resonance imaging (MRI). Analytical data for discrete tissues as well as the entire torso are presented. Generalized equations were derived that enable calculation of whole-torso SAR over a broad range of conditions. In addition, the impedance method can generate data about internal distributions of SAR, which are needed to predict critical organs that might undergo excessive elevations of temperature. Fair to good agreement was found between impedance-method SAR and those predicted by simple phenomenological models.

Electromagnetic Fields↗
PubMed2004

Analytical monitoring of alcoholic fermentation using NIR spectroscopy.

Alcoholic fermentation under Saccharomyces cerevisiae yeasts is governed largely by glucose uptake, biomass formation, ethanol and glycerin production, and acidification. In this work, PLS calibration models were developed with a view to determining these analytical parameters from near infrared spectra and analytical data provided by the corresponding reference methods. The models were applied to a set of samples obtained from various fermentation processes. The glucose, ethanol, and biomass values predicted by the models exhibited a high correlation with those provided by the reference method.

Algorithms↗
PubMed2005

Monitoring complex media fermentations with near-infrared spectroscopy: comparison of different variable selection methods.

Near-infrared spectroscopy (NIRS) is known to be a suitable technique for rapid fermentation monitoring. Industrial fermentation media are complex, both chemically (ill-defined composition) and physically (multiphase sample matrix), which poses an additional challenge to the development of robust NIRS calibration models. We investigated the use of NIRS for at-line monitoring of the concentration of clavulanic acid during an industrial fermentation. An industrial strain of Streptomyces clavuligerus was cultivated at 200-L scale for the production of clavulanic acid. Partial least squares (PLS) regression was used to develop calibration models between spectral and analytical data. In this work, two different variable selection methods, genetic algorithms (GA) and PLS-bootstrap, were studied and compared with models built using all the spectral variables. Calibration models for clavulanic acid concentration performed well both on internal and external validation. The two variable selection methods improved the predictive ability of the models up to 20%, relative to the calibration model built using the whole spectra.

Algorithms↗
PubMed1980

Profiles in altered metabolism. II--(omega -- 1)-hydroxyacid excretion in a case of episodic hypoglycemia.

A patient with recurrent severe hypoglycemia resembling Reye's syndrome was found to have large accumulations of omega -- 1 hydroxy and keto acids in serum and urine that persisted following clinical recovery. A deficiency of mitochondrial medium chain acyl CoA dehydrogenase activity is proposed on the basis of evidence obtained using gas chromatographic mass spectrometric techniques. Analytical data is presented that will allow the recognition of ths variant presenting in other patients.

Acute Disease↗
PubMed1980

2,5-Di-t-amyl-p-benzoquinone: an antioxidant encountered during the analysis of human tissues.

The title compound was found in extracts of several human tissues, including neurological tumors, adult brain and fetal brain. It was also present in adhesive tapes used in the laboratory to label glassware, but not in sufficient quantities to be responsible for contamination of the tissues. No source of contamination was found in the hospital. One possible source is an antioxidant used in rubber manufacture. Analytical data are also given for related benzoquinones and hydroquinones.

Antioxidants↗
PubMed1981

The importance of natural variabilities in the total analytical scheme.

Concentrations of synthetic organics and trace metals in tissues or sediment may vary by hundreds of percents even when replicate samples are collected from the same biological population, i.e. school of fish, or the same location on the bottom of the stream. Without a knowledge of these variations, decisions based on analytical data interpretations are difficult and often in error. Some reasons for these variations will be discussed, with examples presented from field data which include: trace metals and pesticides in bottom sediments, pesticides in suspended sediments and plankton, pesticides in fish populations and trace metals in mollusks.

Analysis of Variance↗
PubMed1987

Quantitative analysis of S3341 in human plasma and urine by combined gas chromatography-negative ion chemical ionization mass spectrometry: 15 month inter-day precision and accuracy validation.

A new quantitative assay for the determination of S3341, an alpha-2 agonist antihypertensive drug, has been developed using combined gas chromatography-negative ion chemical ionization mass spectrometry. The [M]-. ions from TFA derivatives of S3341 (m/z 276) and the internal standard (2H4)S3341 (m/z 280) are monitored simultaneously by selected ion monitoring. For S3341 concentrations ranging from the limit of detection (0.2 ng ml-1 using 1 ml of plasma) to 5 ng ml-1, the average assay precision (CV) is approximately 7% while the average assay accuracy (percentage of error) is 4%. Validation of the day-to-day precision and accuracy was realized after analysing control plasma samples (n = 295) concurrently with the biological samples collected during the pharmacokinetic studies conducted over 15 months. The average day-to-day precision (CV) and accuracy (percentage of error) are 10% and 6% respectively, thus indicating that this assay procedure routinely provides reliable analytical data.

Adrenergic alpha-Agonists↗
PubMed2007

Enhanced efficiency due to the use of achiral additives in the optical resolution of 1-phenylethylamine by its glutaric acid derivative.

Racemic 1-phenylethylamine was optically resolved by its own derivative formed with glutaric acid namely (+)-(R)-N-(1-phenylethyl)glutaramic acid. The amide acid resolving agent was synthesized from (+)-(R)-1-phenylethylamine by N-derivatization. The glutaric acid derivative was the next in a homologous series of dicarboxilic acid derivatized resolving agents of racemic 1-phenylethylamine. Resolution results obtained with the oxalic, malonic, and succinic acid derivatives were previously discussed(1). Each of the above derivative resolving agents could be successfully applied as resolving agents of 1-phenylethylamine. The efficiency of the present optical resolution using (+)-(R)-N-(1-phenylethyl)glutaramic acid resolving agent was remarkably inferior to the results obtained by its shorter chained homologues(1). Use of achiral additives, like urea, thiourea, N-methylurea, and N,N'-dimethylurea caused large increase in the efficiency of the resolution by (+)-(R)-N-(1-phenylethyl)glutaramic acid resolving agent. Precipitated salts obtained in the resolutions performed in the presence of the additives were investigated by thermoanalysis, X-ray powder diffraction, and optical microscopy. Based on the analytical data, the improvement of the resolution results was attributed to the influence of the additives on the crystal nucleation processes of the diasteromeric salts.

Journal Article↗
PubMed1998

A critical evaluation of the application of capillary electrophoresis to the detection and determination of 1,4-benzodiazepine tranquilizers in formulations and body materials.

Studies of the capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) behaviour of 1,4-benzodiazepines have seen application in subject areas such as the development of pharmaceuticals, therapeutic drug monitoring and forensic toxicology. In the development of pharmaceuticals, pKa determinations by CZE can be used in preclinical studies whereas analytical data on the detection and determination of 1,4-benzodiazepines is of value primarily in raw material/formulation assay and in the analysis of body fluids in clinical studies. The capillary electrophoresis (CE) techniques, which generally have inferior limits of detection (LOD) to rival techniques such as gas chromatography (GC) and high-performance liquid chromatography (HPLC), are particularly applicable in forensic toxicology where reasonably high concentrations of these drugs can be encountered. It is anticipated that, with the interfacing of CZE and capillary electrochromatography (CEC) with mass spectrometry (MS) techniques, the excellent selectivity of CZE and particularly CEC will be effectively combined with the sensitivity of MS and the identification capabilities of tandem mass spectrometry (MS/MS) and MS hyphenated (MSn) techniques.

Animals↗
PubMed1983

Evaluation of nutrient value and a classification of food products of animal origin in accordance with reconsidered water/protein ratio.

Water/protein ratio, criterion of evaluation of comparative nutrive value of meat products, fully used at present in some European countries, does not take into account the nutritive value of protein from the structure. This work presents a reconsideration of the evaluation of food proteinogenic value, on the basis of numerous analytical data from collagen dosing and setting of collagen/protein ratio as well as from biological tests on laboratory animals, thus correcting the amount of total protein and, implicitly, water/protein ratio. Tables of these products structure and classification in accordance with water/protein ratio are given.

Animals↗
PubMed1989

Using survival methods to estimate age-at-onset distributions for genetic diseases with an application to Huntington disease.

Two important considerations in genetic disease are the risk of inheriting the gene for a disease and the age-at-onset distribution among those inheriting it. This paper describes the use of survival data analytic methods to estimate these entities. When a sample consists of children and/or siblings of affected individuals, standard life-table methods such as Kaplan-Meier techniques can be applied. The desired estimators are functions of the Kaplan-Meier estimator and their properties are derived using the invariance principle and delta methods. A discussion of the underlying assumptions and estimators of standard errors and mean onset age are given. In an application to Huntington disease, the risk (+/- SE) of inheriting the gene for disease among children of a singly affected parent is estimated to be 0.499 +/- 0.020 and the estimated mean onset age (+/- SE) is 45.6 +/- 0.7.

Actuarial Analysis↗
PubMed2002

Reflections on creative aspects of psychoanalytic diagnosing.

This paper explores the therapeutic value of considering psychoanalytic diagnoses as co-constructions, and emphasizes two interrelated points: First, there are distinctions between medical, psychiatric, and psychoanalytic diagnoses, and similarly, a distinction may be drawn between diagnoses as nouns and the activity of diagnosing. Second, the author stresses that psychoanalytic diagnoses are theory bound. Various competing theories facilitate or interfere with the maintenance of an optimal analytic attitude. Some theories facilitate an analyst's urge to engage in the activity of diagnosing, which may reflect a destructive countertransference enactment. Analytic data in support of these premises is presented and discussed.

Borderline Personality Disorder↗
PubMed1981

Methylmercury poisoning in the Iraqi suckling infant: a longitudinal study over five years.

In a five-year longitudinal study of mothers and infants exposed to methylmercury during the Iraq epidemic of 1972, the frequencies of signs and symptoms exhibited by the mothers were typical of methylmercury poisoning. When blood concentrations of mercury are corrected to 1 March 1972, mothers with the most severe signs and symptoms had an average blood mercury concentration significantly higher (p less than 0.01) than either the milder or asymptomatic groups. Analytical data indicate that the predominant route of exposure for the infant was through breast milk in which approximately 60% of total mercury was determined, by cold vapor atomic absorption, to be organic mercury. Abnormal neurological signs in these infants became more obvious with time: hyperreflexia was observed in 8 of 22 infants at first examination, and in 17 of 22 at second examination. Delayed motor development became evident at the second and third examinations. The frequency of pathological reflexes and delayed motor developmental milestones was so high as to be considered significant even in the absence of a controlled study. There was no increase in mortality as compared to a control group.

Female↗
PubMedDate not supplied

The dermal bioavailability of radiolabelled benzo[a]pyrene from acetone or from oils of differing viscosity, assessed by DNA and protein binding.

Tritium-labelled benzo[a]pyrene ([3H]BaP) was applied to mouse skin in acetone or mineral oils of differing viscosity. Epidermal DNA and protein were extracted after 24 or 48 h and the degree of adduct formation determined by the radioactivity present. When [3H]BaP was applied in acetone, the degree of DNA and protein binding was around 15-20 times greater than that observed when a low-viscosity oil was used as a vehicle. When applied in oils of differing viscosity, however, only a twofold difference was seen across the whole viscosity range (13.5 cSt* at 40 degrees C to 1665 cSt at 60 degrees C). From measurements made of urine and faecal radioactivity and from small-scale investigations using other routes of administration, it was clear that the grooming activity of the animals had a marked effect on skin absorption and macromolecular binding. It is possible that greater grooming activity with low-viscosity oils may explain why oil viscosity did not have a greater effect on binding levels, but further studies are needed to investigate this. These findings may have important implications in the interpretation of long-term skin painting studies and may assist in the interpretation of analytical data and short-term biological assays.

Acetone↗