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  • 1995-1999  (11)
  • 1990-1994  (25)
  • 1930-1934
  • Cell & Developmental Biology  (14)
  • Organic Chemistry  (9)
  • Occupational Health and Environmental Toxicology  (6)
  • Engineering  (4)
  • microspheres  (3)
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Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Development and Evaluation of Sustained-Release Ibuprofen–Wax Microspheres. II. In Vitro Dissolution Studies (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 575-579 
    Details
    ISSN: 1573-904X
    Keywords: ibuprofen ; microspheres ; dissolution ; matrix drug release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A modified USP paddle method using minibaskets was used to study the effects of various formulations on in vitro dissolution of ibuprofen microspheres. Formulations containing waxes such as paraffin or ceresine wax without modifiers exhibited very slow dissolution profiles and incomplete release, which did not improve with increased drug loading or the preparation of smaller microspheres. The addition of modifiers such as stearyl alcohol and glyceryl mono-stearate greatly increased the dissolution rate, with 20% (w/w) near the optimum for predictable dissolution. Higher drug loading and decreased microsphere size increased the dissolution rate from microspheres containing modifier. Optimum formulations contained ceresine wax or microcrystalline wax and stearyl alcohol as a modifier, with a drug content of 17%. An increase in the encapsulation dispersant concentration had little effect on the dissolution profiles. The dissolution data from narrow size fractions of microspheres indicated spherical matrix drug release kinetics; the 50% dissolution time decreased with the square of the microsphere diameter. With appropriate modifiers, wax microsphere formulations of drugs with solubility characteristics similar to those of ibuprofen can offer a starting basis for predictable sustained release dosage forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018931002991
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of Aristotelia-Type Alkaloids. Part XVPart XIV: See [1].. Total synthesis of (+)-hobartinol (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 292-300 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic (+)-makomakine (6) was transformed in six steps into (+)-17R,18R)-17,18-dihydrohobartine-17,18-diol ((+)-5) with an overall yield of 38% (Scheme 2). This compound was shown to be identical with natural hobartinol, a monoterpene indole alkaloid from Aristotelia australasica, originally believed to be the (17S)-epimer 1. At the same time, the synthesis of (+)-5 delineates the hitherto unknown absolute configuration of this metabolite.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780204
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  • 3
    Electronic Resource
    Electronic Resource
    Middle-ear development: II. Morphometric changes in the conducting apparatus of the chick (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 212 (1992), S. 257-267 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogeny of various middle-ear structures was examined in 11 groups of chicks between 10 days embryonic and adult. Measurements of the tympanic membrane surface area and height, columella length, and that of the columella footplate, annular ligament, and oval window area were obtained using video micrographs and computer digitization techniques. The oval window matures first at 53 days post-hatching, whereas the columella achieves adult size at 74 days. The tympanic membrane surface area is the last middle-ear variable studied to reach adult size (79 days post-hatch). The columella increases its length from 0.63 mm (10 days embryonic) to 2.73 mm in the adult. The tympanic membrane area expands by 280% whereas the columellar footplate area increases by 11x. As a result, the pressure amplification of the middle ear due to the tympanic membrane/columellar footplate area ratio improves by over 400%. These data further contribute to our understanding of the functional development of the middle ear. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052120305
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  • 4
    Electronic Resource
    Electronic Resource
    Development and Evaluation of Sustained-Release Ibuprofen-Wax Microspheres. I. Effect of Formulation Variables on Physical Characteristics (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 1377-1383 
    Details
    ISSN: 1573-904X
    Keywords: ibuprofen ; waxes ; microspheres ; modifiers ; size analysis ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A congealable disperse phase encapsulation method was used to prepare sustained-release ibuprofen-wax microspheres. Microspheres prepared with paraffin wax, such as ceresine and micro-crystalline waxes, using polyvinylpyrrolidone (PVP) as dispersant had a tendency to aggregate, but the addition of wax modifiers (stearyl alcohol and glyceryl monostearate) greatly reduced aggregation. Optimum modifier and dispersant concentrations were 20% (w/w) and 5% (w/v), respectively. The particle size distribution of the microspheres was log-normal. An increase in modifier, dispersant concentration, emulsification stirring speed, or temperature shifted the size distribution toward finer particles. Microcrystalline wax required a higher emulsification temperature and produced finer particles than ozokerite wax. The recovery of drug from the different microsphere formulations varied between 71 and 92%. Differential scanning calorimetry (DSC) of the single components and physical mixtures showed endothermic peaks at the respective melting-point ranges. The DSC of the ceresine and microcrystalline wax microspheres was similar to rescans of ternary mixtures of components of the microspheres with less prominent and lower melting temperatures than individual components or physical mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015845022112
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of Drug Loading and Molecular Weight of Cellulose Acetate Propionate on the Release Characteristics of Theophylline Microspheres (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 1396-1400 
    Details
    ISSN: 1573-904X
    Keywords: microspheres ; encapsulation ; drug loading ; dissolution ; cellulose acetate propionate ; molecular weight ; theophylline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Microspheres with 40, 50, and 60% drug loading of anhydrous theophylline core material were prepared by the emulsion-solvent evaporation method. Three different molecular weights of cellulose acetate propionate were used as encapsulating polymers. The geometric mean diameter of the microspheres increased with drug loading for all polymers. Dissolution rate for a given particle size fraction also increased with drug loading for all polymers. Higuchi/Baker-Lonsdale spherical matrix dissolution kinetics were followed by narrow particle size fractions of the microspheres. A linear relationship between the T-50% (time required for 50% of the drug to be released) and the square of microsphere diameter was observed with all three molecular weights of the encapsulants. The slowest drug release was obtained with the high molecular weight polymer, which also produced the smoothest microspheres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015801207091
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  • 6
    Electronic Resource
    Electronic Resource
    N-Acetyl-D and L-esters of 5′-AMP hydrolyze at different rates (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 150-153 
    Details
    ISSN: 0899-0042
    Keywords: aminoacyl adenylate esters ; hydrolytic stabilization by intramolecular interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of the properties of aminoacyl derivatives of 5′-AMP are aimed at understanding the origin of the process of protein synthesis. Aminoacyl (2′,3′) esters of 5′-AMP can serve as models of the 3′-terminus of aminoacyl tRNA. We report here on the relative rates of hydrolysis of AC-D- and L-Phe AMP esters as a function of pH. At all pHs above 3, the rate constant of hydrolysis of the AC-L-Phe ester is 1.7 to 2.1 times that of AC-D-Phe ester. The D-isomer seems partially protected from hydrolysis by a stronger association with the adenine ring of the 5′-AMP. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050308
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  • 7
    Electronic Resource
    Electronic Resource
    Disposition kinetics of ML-1035 sulfoxide enantiomers and the prochiral sulfide in rats (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 428-435 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric pharmacokinetics ; benzamides ; gastroprokinetic agents ; prochirality ; chiral sulfoxidation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ML-1035, 4-amino-5-chloro-2-[2-(methylsulfinyl)ethoxy]-N-[2-(diethylamino)ethyl]benzamide, is a sulfoxide compound and a racemic gastroprokinetic agent with a chiral center at the sulfur atom. We have investigated the disposition kinetics of (R)-ML-1035 sulfoxide (R) and (S)-ML-1035 sulfoxide (S) after the single enantiomers and the racemic mixture were administered to rats in separate experiments. There was no noticeable chiral inversion after either enantiomer dose. Both enantiomers were rapidly absorbed. After dosing with enantiomers or with the racemate, the resulting plasma concentration-time curve of R was closely parallel to that of S in both intravenous and oral experiments, suggesting that the two enantiomers have approximately the same disposition kinetics. After intravenous enantiomer doses, only S underwent conversion to sulfide, suggesting that sulfidation in the liver is enantioselective. However, the enantioselective sulfidation after intravenous dosing did not introduce a difference in the global plasma disposition profiles between R and S, since the reduction reaction is a minor metabolic process. Other metabolic reactions such as sulfonation and mono-N-desethylations were not enantioselective. After oral administration, conversion to sulfide was observed for both enantioners, implicating the existence of a nonhepatic pathway in sulfidation. Administration of a prochiral sulfide dose was associated with an enantioselective sulfoxidation, in which the R/S concentration ratios increased as a function of time. In addition, enantiomeric interaction causing changes in pharmacokinetic parameters was observed after the oral racemate dose, while the interaction is negligible after an intravenous racemate dose, indicating a route dependency in enantiomeric interaction. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050607
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  • 8
    Electronic Resource
    Electronic Resource
    Middle-ear development VI: Structural maturation of the rat conducting apparatus (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 239 (1994), S. 475-484 
    Details
    ISSN: 0003-276X
    Keywords: Middle ear ; Auditory ; Hearing development ; Ossicles ; Tympanic membrane ; Rat (Long Evans strain) ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The contribution of middle-ear development to the overall development of hearing has not been explored in great detail. This presentation describes the maturation of conductive elements in the rat middle ear, and provides the basis on which future studies of middle-ear functional development will follow.Methods: The middle-ear apparatus was examined at nine different ages (between 1 and 80 days postpartum) in Long Evans rats. At each age elements of the conducting apparatus were observed with either light or scanning electron microscopy (SEM), and quantitative measurements were made from video enhanced photomicrographs. Tympanic membrane area and cone depth, the length of the malleus and incus arms, ossicular weight, stapes foot plate and oval window areas, and bulla volume were all measured. Development of the area and lever ratios were derived from these measurements. The data were fitted to exponential equations and the time in days required to reach 90% of the adult level determined.Results: The pars tensa achieved 90% of total area by 17 days. The oval window achieved the 90% criterion by 13 days, while the area ratio was within 10% of its adult size by 8 days. The ossicles took between 26 and 34 days, while bulla volume took 59 days to reach the 90% level.Conclusions: Middle-ear growth was very orderly and systematic in the data reported. When maturation of the area ratio was considered against development of the endocochlear potential or the round window compound action potential, it was clear that the growth of this important aspect of the middle ear preceded the onset of cochlear function. © 1994 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092390413
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  • 9
    Electronic Resource
    Electronic Resource
    Changes in the morphology and phosphatase cytochemistry of the Golgi region of hepatocytes during the acute phase response to inflammation (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 241 (1995), S. 439-450 
    Details
    ISSN: 0003-276X
    Keywords: Golgi ; TGN ; Inflammation ; Acute phase response ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: During the acute phase response to inflammation, the Golgi apparatus of rat hepatocytes processes an increased quantity of glycoproteins, in the form of acute phase reactants.Methods: The compartmental organization of the hepatocyte Golgi of control and 24 hour inflamed rats was studied, using transmission electron microscopic techniques, including cytochemistry, to detect nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) activity.Results: In inflamed rats, individual Golgi stacks were enlarged, but retained their organization into four compartments:1) a phosphatase negative, perforated cis-element, 2) two mid-saccules which sometimes were positive for NADPase, 3) one or occasionally two NADPase and TPPase positive trans-saccules, and 4) a tubulovesicular trans-Golgi network (TGN) which was NADPase reactive and contained a spotty TPPase reaction product. Two of these compartments were noticably altered in response to inflammation. The two mid-saccules were consistently and uniformly dilated. The TGN was altered to the point of being difficult to recognize and had acquired CMPase reactivity. In control rats the TGN consisted of anastomosing tubules forming cage-like structures; secretory granules containing lipoprotein particles pinched off from these. In inflamed rats, most of the cage-like TGN structures had been replaced with an extensive vesicular syncytium which produced secretory granules with a granulofilamentous content.Conclusions: In hepatocytes from inflamed rats an apparent switch had occured in the type of secretory material processed by the Golgi apparatus. Furthermore, the inflammation-induced increase in the size of individual Golgi stacks apparently was not due to a parallel increase in size of all Golgi saccules. Rather, saccules within given Golgi compartments responded in a characteristic and specific manner to the increase in glycoprotein processing that occurs during inflammation. © 1995 Wiley-Liss, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092410402
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  • 10
    Electronic Resource
    Electronic Resource
    Cytoarchitecture of the substantia nigra pars lateralis in the opossum (Didelphis virginiana): A correlated light and electron microscopic study (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 241 (1995), S. 563-578 
    Details
    ISSN: 0003-276X
    Keywords: Substantia nigra ; Basal ganglia ; Cytoarchitecture ; Light microscopy ; Electron microscopy ; Opossum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The substantia nigra has been divided into three subdivisions. However, the cytoarchitecture of one of these subdivisions, the pars lateralis (SNI), has not been previously examined in detail at the light and electron microscopic levels in any species. In the adult opossum, the three nigral subdivisions can be easily distinguished as distinct, rostrocaudally oriented cell groups separated by neuron-free zones. Thus it was possible to determine the boundaries of the SNI unambiguously. This report covers the results of an examination of the morphology and organization of the SNI in the opossum.Methods: Material from 13 opossums was used for this study. Eight of the animals had been previously stained for Nissl substance (n=4) or impregnated by the Golgi technique (n=4). The remaining five animals were prepared for electron microscopic studies using standard procedures.Results: Two cell types were identified on the basis of morphological differences, small and medium-large neurons. Small neurons (10-18 μm long axis) have large nuclei with moderate amounts of heterochromatin and a thin rim of cytoplasm. They have long (up to 500 μm), spine-free dendrites. Medium-large neurons (18-54 μm long axis) have rounded nuclei with electron-lucent nucleoplasm. Few indentations of the nuclear envelope were observed. The surrounding cytoplasm has dense arrays of organelles. Nissl bodies are particularly prominent in the form of pyramids with their bases at juxtanuclear positions and their apices directed toward emerging dendrites. Dendrites of medium-large neurons are long (some〉1 mm in length), are primarily oriented in the frontal plane, and extend along the dorsal surface of or into the cerebral peduncle. Some cells have dendrites that are moderately spinous, whereas other neurons possess sparsely spinous dendrites. Relatively few synaptic profiles are observed to contact somata and proximal dendrites.Conclusion: This report provides added morphological support for the idea that the SNI is a distinct subdivision of the substantia nigra, a distinction previously made on the basis of the physiologically characterized relationship between the lateral substantia nigra and orienting behaviors and seizure-related function. © 1995 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092410414
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