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  • Chemical Engineering  (22)
  • Analytical Chemistry and Spectroscopy  (21)
  • pharmacokinetics  (5)
  • melanoma  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Trophic factors and central nervous system metastasis (1995)
    Springer
    Cancer and metastasis reviews 14 (1995), S. 303-321 
    Details
    ISSN: 1573-7233
    Keywords: brain metastasis ; melanoma ; tumor progression ; growth factors ; neurotrophins ; nerve growth factor ; melanotropins ; signal transduction ; tyrosine receptor kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To metastasize to the central nervous system (CNS) malignant cells must attach to brain microvessel endothelial cells, respond to brain endothelial cell-derived motility factors, respond to CNS-derived invasion factors and invade the blood-brain barrier (BBB), and finally, respond to CNS survival and growth factors. Trophic factors such as the neurotrophins play an important role in tumor cell invasion into the CNS and in the survival of small numbers of malignant cells under stress conditions. Trophic factors promote BBB invasion by enhancing the production of basement membrane-degrading enzymes in neurotrophin-responsive cells. The expression of certain neurotrophin receptors on brain-metastasic neuroendrocrine cells occurs in relation to their invasive and survival properties. For example, CNS-metastatic melanoma cells respond to particular neurotrophins (nerve growth factor, neurotrophin-2) that can be secreted by normal cells within the CNS. In addition, a paracrine form of transferrin is important in CNS metastasis, and brain-metastatic cells respond to low levels of transferrin and express high levels of transferrin receptors. CNS-metastatic tumor cells can also produce autocrine factors and inhibitors that influence their growth, invasion and survival in the brain. Synthesis of paracrine factors and cytokines may influence the production of trophic factors by normal brain cells adjacent to tumor cells. Moreover, we found increased amounts of neurotrophins in brain tissue at the invasion front of human melanoma tumors in CNS biopsies. Thus the ability to form metastatic colonies in the CNS is dependent on tumor cell responses to trophic factors as well as autocrine and paracrine growth factors and probably other underdescribed factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690600
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  • 2
    Electronic Resource
    Electronic Resource
    An Experimental Model for Measuring Middle Ear Antimicrobial Drug Penetration in Otitis Media (1990)
    Springer
    Pharmaceutical research 7 (1990), S. 1242-1247 
    Details
    ISSN: 1573-904X
    Keywords: otitis media ; pharmacokinetics ; amoxicillin ; trimethoprim ; sulfamethoxazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bacteria are an important cause of acute otitis media and successful treatment depends on achieving inhibitory or bacteriacidal antimicrobial drug concentrations in the middle ear. To evaluate further otitis media treatment success and failure, we developed a chinchilla model to study antimicrobial drug penetration through the middle ear mucosa. Using quantitative histomorphometry, we measured the middle ear space in 10 chinchillas and found a mean ±SD volume of 2.09 ± 0.08 ml and a mean SD surface area of 14.41 ± 1.48 cm2. To measure the apparent rate constant (K e) of antibiotic elimination from the middle ear, through the middle ear mucosa, an antibiotic solution was inoculated into the middle ear cavity, and samples were aspirated between 1 and 8 hr later. In normal ears, the mean K e ±SD for amoxicillin was 0.118 ± 0.013 hr−1, that for a trimethoprim 0.461 ± 0.090 hr−1, and that for sulfamethoxazole 0.265 ± 0.062 hr−1. In ears inoculated with type 7F Streptococcus pneumoniae to induce acute otitis media, the K e ±SD increased for all three drugs (P 〈 0.05): amoxicillin to 0.286 ± 0.089 hr−1, trimethoprim to 0.662 ± 0.118 hr−1, and sulfamethoxazole to 0.411 ± 0.056 hr−1. These values demonstrate that amoxicillin had the lowest apparent penetration rate constant of the three antibiotics but the greatest increase from normal to infected mucosa (142%). Trimethoprim had the highest apparent penetration rate constant of the three antibiotics but the smallest increase from normal to infected mucosa (44%), while the sulfamethoxazone apparent penetration rate constant increased from normal to infected mucosa by 55%. The K e for amoxicillin was the same for inoculation volumes of 0.8 and 1.6 ml (P = 0.557) and the same for sampling intervals of 4 and 8 hr (P = 0.054). All three antimicrobial drug concentration–time curves were log-linear, as predicted by Fick's first law of diffusion. In conclusion, this model overcomes the technical limitations of previous models and permits investigation of the many factors that can influence antibiotic penetration into the middle ear and reduce otitis media treatment efficacy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015977603224
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  • 3
    Electronic Resource
    Electronic Resource
    Malignant melanoma metastasis to brain: role of degradative enzymes and responses to paracrine growth factors (1993)
    Springer
    Journal of neuro-oncology 18 (1993), S. 139-149 
    Details
    ISSN: 1573-7373
    Keywords: melanoma ; metastasis ; proteases ; endoglycosidases ; growth factors ; growth factor receptors ; basement membrane ; blood brain barrier ; neurotrophins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mouse and human melanoma cells metastatic to the brain express degradative enzyme activities that are used for invasion of brain basement membrane and parenchyma. Compared to poorly metastatic or lung- or ovary-metastatic murine melanoma lines, the brain-metastatic sublines secreted higher levels of a variety of degradative enzymes. Brain-metastatic murine and human melanoma cells also degraded subendothelial basement membrane and reconstituted basement membrane at rates higher than other metastatic melanoma cells. In some cases these degradative activities in mouse and human melanoma cells can be induced by paracrine factors known to be present in the brain parenchyma, such as nerve growth factor (NGF). NGF stimulates the expression of degradative enzymes, such as the endo-Β-glucuronidase heparanase, that are important in basement membrane penetration but this factor does not stimulate melanoma cell growth. The growth of brain-metastasizing melanoma cells appears to be stimulated by other paracrine growth factors, such as paracrine transferrin. Melanoma cells metastatic to brain express higher numbers of transferrin receptors and respond and proliferate at lower concentrations of transferrin than do melanoma cells metastatic to other sites or poorly metastatic melanoma cells. The results suggest that degradation and invasion of brain basement membrane and responses to paracrine neurotrophins and paracrine transferrins are important properties in brain metastasis of murine and human malignant melanoma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050420
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  • 4
    Electronic Resource
    Electronic Resource
    Direct measurement of dietary fractional absorption using calcium isotopic tracers (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 603-607 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fractional dietary Ca absorption, ‘a’, is measured by determining the ratio of two stable isotopic tracers, one of them orally (44Ca @ 0.2-0.5 mg/kg) and the other intravenously (42Ca @ 0.02-0.1 mg/kg). Thermal ionization mass spectrometry (TIMS) is used to measure the perturbation of natural abundance isotope ratios (delta % excess). Typical sensitivity of the TIMS permits detection of a 2.5 delta % excess change from the natural Ca isotope ratio with relative standard deviations of about 0.5%. At sufficiently long times absorption becomes constant so that ‘a’ is determined by a product of constants and a measured ratio.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200141105
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  • 5
    Electronic Resource
    Electronic Resource
    Computerized analysis of tumor cells flowing in a parallel plate chamber to determine their adhesion stabilization lag time (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 26 (1993), S. 88-98 
    Details
    ISSN: 0886-1544
    Keywords: transglutaminase ; melanoma ; digital image analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The importance of cell adhesion in a variety of physiological phenomena requires development of an understanding of the factors and molecular mechanisms underlying these behaviors. Cell adhesion is a multistep process involving primary receptor-ligand interactions followed by secondary events that may lead to the formation of focal contacts. Due to the lack of well-defined assays to study adhesion stabilization, little is known about this process, except that it may involve signaling events, receptor recruitment, and, as we have demonstrated, covalent peptide cross-linking by cell membrane-associated transglutaminase [Menter et al.: Cell Biophys. 18:123-143, 1992]. To study the stabilization process we have developed a dynamic assay employing a parallel plate flow chamber coupled with video microscopy and digital image processing. Our studies utilize wheat germ agglutinin-selected human metastatic melanoma cell variants that exhibit differences in their experimental metastatic potential and expression of transglutaminase. Using this assay, quantifying cell-substrate stabilization was found to be quick, reliable, reproducible, and useful in evaluating agents that block this process. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970260109
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  • 6
    Electronic Resource
    Electronic Resource
    Substituent effects in the mass spectrometry of 4-substituted camphors studied under electron and chemical ionization (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 876-880 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron ionization mass spectra of fourteen 4-substituted (4-X) camphors have been recorded and analyzed using metastable ion analysis and exact mass measurement. With respect to camphor, alkyl substituents changed the relative importance of different fragmentation pathways, though they did not induce new fragmentations. Substituents X connected to the camphor framework through an atom having a lone pair of electrons were generally lost as HX. Overall the fragmentation behaviour was essentially independent of the inductive substituent constant. Under chemical ionization conditions, only methane of the reagent gases produced extensive fragmentations of these compounds; isobutane, acetone and ammonia were ineffective. The nature of the fragmentations was independent of both the inductive substituent constant of the substituent X and the proton affinity and heat of formation of the corresponding neutral compound HX.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081104
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and use of a novel chiral surfactant based on (R,R)-tartaric acid and its application to chiral separations in micellar electrokinetic capillary chromatography (MECC)Presented at the 17th International Symposium on Capillary Chromatography and Electrophoresis, Wintergreen, Virginia, USA, May 1995 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 513-520 
    Details
    ISSN: 1040-7685
    Keywords: chiral ; separation ; micellar ; capillary ; electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the synthesis of a novel chiral surfactant based on (R,R)-tartaric acid. (R,R)-Tartaric acid is acetylated while simultaneously forming a cyclic anhydride, which is then reacted with n-decylamine forming a chiral, long chain carboxylic acid. This carboxylic acid is then further reacted with the achiral amino acid taurine forming the required surfactant which has a sulfonic acid headgroup. Evidence for its surface activity and an estimate of its critical micelle concentration (cmc) have been obtained using surface tension measurements and conductivity. The surfactant has then been used as the additive in micellar electrokinetic capillary chromatography (MECC) to achieve chiral separations of compounds with multiple aromatic functionality. These separations are compared with those achieved with previously reported tartaric acid based surfactants which show a difference in selectivity. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220070512
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  • 8
    Electronic Resource
    Electronic Resource
    Direct observation of a DNA quadruplex by electrospray ionization mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 181-183 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In 10 mM sodium phosphate, pH 7.6, containing 0.1 mM ethylenediaminetetraacetic acid, ions corresponding to the non-covalent, four-stranded oligonucleotide, d(CGCG4GCG)4, were detected by negative ion electrospray ionization (ESI) mass spectrometry at a low nozzle-skimmer (ΔNS) bias (-150 V), but not at a higher ΔNS bias (〉 -250 V). In contrast, when the sample was desalted and analyzed by ESI mass spectrometry at a low ΔNS bias only ions for the single-stranded d(CGCG4GCG) species were observed. These data agree with spectroscopic evidence which showed that oligonucleotides with the sequence motif 5′d(CGCGnGCG)3′, where n = 2-5, formed stable four-stranded complexes in the presence of monatomic cations, like K+, Ca2+, Na+ and Li+, but not in their absence.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200220307
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  • 9
    Electronic Resource
    Electronic Resource
    Impact strength and melt viscosity of bisphenol-a polycarbonate and styrene-maleic-anhydride copolymer blends (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 896-902 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mixtures of 90, 80, and 70 percent by weight bisphenol-A-polycarbonate (PC) and 10, 20, and 30 percent by weight styrene maleic anhydride (SMA) copolymer were melt-blended in a single screw extruder. Differential scanning calorimetry (DCS) and scanning electron microscopy (SEM) were used to determine the miscibility of the blends. The viscosity, as a function of shear rate and temperature, was measured by an Instron capillary viscometer. The notched impact strength as a function of temperature was measured by an Izod impact tester.The results of DSC showed two glass transition temperatures which merged slightly towards each other, indicating marginal miscibility of these blends. There was a decrease in viscosity as the fraction of SMA copolymer was increased. The most significant decrease occurred with the initial addition of SMA copolymer. The viscosity also decreased with increases in temperature. The impact strength of the blends was also dependent on SMA copolymer content. The blends showed six to ten times lower impact strengths at room temperature than the 100 percent polycarbonate. SEM analysis helped to determine the reason why the impact strength was lower for the blends. High magnification showed the presence of SMA copolymer inclusions dispersed throughout the PC matrix. These inclusions, which increased in size as SMA copolymer content was increased, acted as defects in the system.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760251406
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  • 10
    Electronic Resource
    Electronic Resource
    Theoretical basis for variable order assumption in the kinetics of leaching of discrete grains (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 904-907 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390520
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