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  • Antibiotics  (8)
  • Cell & Developmental Biology  (7)
  • 2020-2023
  • 1995-1999  (15)
  • 1975-1979
  • 1
    Electronic Resource
    Electronic Resource
    Distribution of cranial and rostral spinal nerves in tadpoles of the frog discoglossus pictus (Discoglossidae) (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 226 (1995), S. 189-212 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We studied the peripheral nervous system of early tadpoles of the frog Discoglossus pictus using whole-mount immunohistochemistry. Double-labeling of muscles and nerves allowed us to determine the innervation of all cranial muscles supplied by the trigeminal, facial, glossopharyngeal, vagal, and hypoglossal nerves. The gross anatomical pattern of visceral, cutaneous, and lateral-line innervation was also assessed. Most muscles of the visceral arches are exclusively supplied by posttrematic rami of the corresponding branchiomeric nerves, the only exceptions being some ventral muscles (intermandibular, interhyoid, and subarcual rectus muscles). In the mandibular arch, the pattern of motor ramules of the trigeminal nerve prefigures in a condensed form the adult pattern, but the muscles of the hyoid arch are innervated by ramules of the facial nerve in a pattern that differs from that of postmetamorphic frogs. With respect to the nerves of the branchial arches, pretrematic visceral rami, typical of other gnathostomes, are absent in D. pictus. Instead, we find a separate series of posttrematic profundal visceral rami. Pharyngeal rami of all branchial nerves contribute to Jacobson's anastomosis. We provide a detailed description of the lateral-line innervation and describe a new ramus of the middle lateral-line nerve (ramus suprabranchialis). We confirm the presence of a first spinal nerve and its contribution to the hypoglossal nerve in D. pictus tadpoles. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052260207
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical properties of the skin of Xenopus laevis (Anura, Amphibia) (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 224 (1995), S. 15-22 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The skin of the aquatic pipid frog, Xenopus laevis, was examined for specific biomechanical features: (1) thickness, (2) maximal strain at break (εf), (3) tensile strength (σm), (4) modulus of elasticity (E, stiffness), and (5) the area under the stress-strain curve (W) (breaking energy, toughness). Skin freshly removed from dorsal, ventral, and lateral areas of the body was subjected to uniaxial tension. In both sexes, the dorsal skin is thicker than the ventral. The skin of male frogs was consistently thinner in all body regions than that of females. Most biomechanical parameters showed a considerable range of values in both males (εf = 59-63%, σm = 15-16.5 MPa, E = 33.5-38.4 MPa, W = 3.8-4.5 MJ/m3) and females (εf = 102-126%, σm = 11.5 MPa, E = 10.4-12 MPa, W = 5.2-6.7 MJ/m3). The disparate εf values in males (low) and females (high) might reflect sexual dimorphism. Static stress-strain curves were typicxally J-shaped; with the exception of “toe,” the curves rose approximately linearly with increasing strain. The skin of X. laevis, although heterogeneous in structure, possesses features similar to those found in tissues with aligned collagen fibers such as tendons or fish skin. However, in anurans, the skin seems to play a more passive mechanical role during locomotion than in fish. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052240103
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  • 3
    Electronic Resource
    Electronic Resource
    Antibiotics from gliding bacteria, LXIV. Isolation and structure elucidation of sorangiolides A and B, novel macrocyclic lactone carboxylic acids from Sorangium cellulosum (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 867-872 
    Details
    ISSN: 0947-3440
    Keywords: Antibiotics ; Sorangium cellulosum ; Macrolides ; Mass spectrometry ; X-ray structure analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two novel metabolites, sorangiolide A (1) and B (2), were isolated from the mother liquors and side fractions of the sorangicin A pilot-scale production. Their structures were elucidated by 2D-NMR spectroscopy and mass spectrometry as 18-membered macrolactones with a C11-carboxylic acid side chain. Sorangiolide B (2) differs from A (1) by an additional hydroxyl group at C-6 in the side chain. The absolute configuration of sorangiolide A (1) was established by X-ray structure analysis. The sorangiolides show a weak antibiotic activity against Gram-positive bacteria.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199505125
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  • 4
    Electronic Resource
    Electronic Resource
    Antibiotics from gliding bacteria, LXVPart LXIV: Ref.. Synthesis of soraphen analogues by substitution of the phenyl-C-17 ring segment of soraphen A1α (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 803-816 
    Details
    ISSN: 0947-3440
    Keywords: Antibiotics ; Soraphen ; Macrolide antibiotics ; Structure-activity relationship ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The partial synthesis of 11 analogues of soraphen A1α (1) is described. Reductive lactone ring cleavage, transformation into (17R,S)-soraphenic acid 10 and cyclization provided unnatural 17-epi-soraphen A1α (12). Removal of the phenyl-C-17 ring segment of 1 by cleavage of the lactone moiety and the C-16/C-17 bond gave the aldehyde 16 as central intermediate. After homologation of 16, introduction of a new C-17 substituent R or H, and cyclization of the lactone ring, the soraphen analogues butyl-, thienyl-, and tolylsoraphen 2b, d, e and 22b, d, e and the desphenylsoraphen 2a were obtained. The ring-contracted soraphen analogues norsoraphen 29 and 30 and desphenylnorsoraphen 31 were synthesized by introduction of a phenyl group or reduction of the intermediate aldehyde 23 followed by cyclization to the lactone. The biological activity of the soraphen analogues against Candida albicans was determined. Compared to the natural product, all analogues exhibit reduced activity. The activity of the analogues strongly depends upon the nature of the substituent R, the configuration at C-17, and the ring size.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199505118
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  • 5
    Electronic Resource
    Electronic Resource
    Antibiotics from Gliding Bacteria, LXXVIIIPart LXXVII: Ref.. Ripostatin A, B, and C: Isolation and Structure and Structure Elucidation of Novel Metabolites from Sorangium cellulosum (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1657-1663 
    Details
    ISSN: 0947-3440
    Keywords: Antibiotics ; Polyketides ; Sorangium cellulosum ; RNA polymerase inhibitors ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three closely related new metabolites named ripostatins were isolated from the myxobacterium Sorangium cellulosum and their structures elucidated by spectroscopic methods. Two of them, ripostatin A (1a, b) and B (2a), are 14-membered macrolides with an acetic acid and a phenylalkyl side chain, whereas the third metabolite ripostatin C (3a) is an acyclic derivative of ripostatin A. By application of the method of Helmchen the absolute stereochemistry could be determined as (11R,13R) for ripostatin A, 11R,13S,15R for ripostatin B and 11S for ripostatin C. The polyketide origin of A was revealed by feeding experiments with 13C-labeled precursors demonstrating the incorporation of one molecule of phenylacetic acid derived from phenylalanine, one propionate unit, and ten acetate units.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961026
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  • 6
    Electronic Resource
    Electronic Resource
    Antibiotics from Gliding Bacteria, LXXIXPart LXXVIII: Ref.[1].. - Chemical Modification of the Antifungal Macrolide Soraphen A1α: Deoxygenation in the South-East Ring Segment (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 245-252 
    Details
    ISSN: 0947-3440
    Keywords: Antibiotics ; Soraphen ; Macrolide antibiotics ; Structure-activity relationship ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present paper describes the chemical modification of the antifungal macrolide soraphen A1α (1) by selective removal of oxygen substituents in the south-east ring segment. In the course of this investigation two key derivatives were prepared: 4-demethyl-5-O-(4-methoxybenzyl)-4-episoraphen (6) and 3,5-dideoxy-4-oxosoraphen (22). 6 served as precursor for 4-demethoxysoraphen (19) and 4-demethoxy-5-deoxysoraphen (20). 22 was used for the deoxygenation in positions C-3, C-4 and C-5 and for the synthesis of 3,5-didesoxysoraphen (24) as well as 4-demethoxy-3,5-dideoxysoraphen (27). The comparison of the antifungicidal activity of these derivatives showed that the OH group in position C-3 is essential for the biological activity of the soraphens.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970135
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical Modification of Thiangazole A in the Oxazole and Styryl Region (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3381-3392 
    Details
    ISSN: 1434-193X
    Keywords: Antibiotics ; Thiangazoles ; Polythiazolines ; Oxazoles ; Structure-activity relationships ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The partial synthesis of 54 derivatives of thiangazole A (1a), a new polythiazoline antibiotic from Polyangium spec. (myxobacteria), is described. Derivatives with chemical modification of the carboxamide group in the oxazole region were prepared either by N-alkylation to amides 5-14 or by methanolysis to ester 15, and its transformation products 16, 19, 20. Oxidation of the C-5 methyl group of 1a with molecular oxygen led to the hydroxymethyl derivative 21, and two by-products lacking the C-5 methyl group (22), or the entire oxazole ring (23). Key intermediate for analogues with modifications in the styryl region is the aldehyde 27, obtained by direct cleavage of the C-21/C-22 double bond. 27 was transformed into the oximes 37-42 and by Wittig reaction to (21Z)-thiangazole (43) and analogues 44-46 with proton and alkyl residues replacing phenyl. 21,22-Didehydrothiangazole (50) was synthesized in a multi-step reaction from 27 via the 20-alkinyl intermediate 49. The insecticidal activities and inhibition of the respiratory chain (complex I) by the thiangazole analogues were determined and compared with the natural product.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2046/1999/99007_s.pdf or from the author.
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    The Crocacins, Novel Antifungal and Cytotoxic Antibiotics from Chondromyces crocatus and Chondromyces pediculatus (Myxobacteria): Isolation and Structure Elucidation (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1085-1089 
    Details
    ISSN: 1434-193X
    Keywords: Chondromycesspec. ; Myxobacteria ; Antibiotics ; Fungicides ; Structure elucidation ; Relative configuration ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Four novel antifungal and highly cytotoxic metabolites, the crocacins A-D (1-4), were isolated in our screening of the myxobacterial genus Chondromyces from strains of C. crocatus and C. pediculatus. Crocacin A, B, and D (1, 2, and 4) are unusual dipeptides of glycine and a 6-aminohexenoic or -hexadienoic acid, which is N-protected by a complex polyketide-derived acyl residue. The latter is a multiply substituted phenylundecatrienoic acid, which is found as its primary amide crocacin C (3). Based on 1H coupling constants, NOEs and MM+ calculations the relative configuration of the asymmetric centers and their preferred conformation are proposed for the crocacins.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Instructive induction of prostate growth and differentiation by a defined urogenital sinus mesenchyme (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 30 (1995), S. 319-332 
    Details
    ISSN: 1059-910X
    Keywords: Rat ; Prostate ; Epithelium ; Stroma ; Cytodifferentiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Instructive influences of fetal mesenchyme were examined in heterotypic tissue recombinants consisting of urogenital sinus mesenchyme (UGM) from male and female rats and distal ductal tips from adult rat prostate. Tissues were grown under the renal capsule of male hosts for periods up to 28 days. Resultant growths exhibited typical prostate histology. Expression of lobe-specific proteins for the ventral (prostatic steroid binding protein [PSBP]) lateral (seminal vesicle secretion II [SVS II]), and dorsal prostate (secretory transglutaminase [TGase]) were examined by immunocytochemistry. Male or female UGM combined with terminal segments of the ventral or dorsal prostate and immunolabeled with antibodies to lobe-specific proteins demonstrated expression of all three secretory products. The pattern of staining was consistent with a compound inductive response from the UGM. Unique to this study was our ability to use a defined mesenchymal tissue (female ventral mesenchymal pad [VMP]). This tissue is specifically associated with ductal branching morphogenesis and cytodifferentiation of the ventral prostate. Distal ductal tips from the dorsal lobe of the adult male prostate when recombined with female VMP and grown in vivo exhibited transformation of secretory phenotype, and the epithelium expressed mRNAs for PSBP. Immunocytochemistry of serial sections did not demonstrate labeling for TGase in the new epithelial growth. Ultrastructural analysis of the heterotypic recombinants indicated that the epithelium had similar characteristics to those of normal ventral prostate. Early stages of the mesenchymal-epithelial interactions resulted in dedifferentiation of the adult epithelium to solid cords of stratified cells. These findings illustrate the potent instructive capacity of a defined fetal UGM to influence development and cytodifferentiation of adult prostate epithelium. © 1995 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070300407
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  • 10
    Electronic Resource
    Electronic Resource
    Genetic susceptibility to cancer from exogenous and endogenous exposures (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 63 (1996), S. 15-22 
    Details
    ISSN: 0730-2312
    Keywords: bladder cancer ; breast cancer ; ethnicity ; polymorphism prostate cancer ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The past four decades of epidemiological research have yielded valuable information on the risks of populations to environmental exposures such as tobacco, asbestos, and dietary components. Prevention efforts have been focused on large-scale population-based interventions to minimize exposure to such external carcinogens. While some cancers are beginning to show a decline from changing environmental exposures, hormone-related cancers, such as breast and prostate, are becoming more prevalent. The development of these cancers appears to be closely related to endogenous exposures to circulating steroid hormones. Although prevention trials using antihormone agents are proving successful in some instances, the long-term control of these cancers necessitates a clearer understanding of the metabolism and transport of the relevant hormone in vivo.The revolution in molecular biology has provided powerful genetic tools for evaluating mechanisms of cancer causation as well as the potential to better define individual susceptibility. Using tobacco exposure as an example, we and others have demonstrated that polymorphisms in genes controlling aromatic amine metabolism provide at least a partial explanation for ethnic and individual susceptibility to bladder cancer. Similar studies have examined genetic polymorphisms in the metabolism of tobacco smoke and lung cancer risk, red meat and colorectal cancer, and aflatoxin and liver cancer.Our current studies have pursued a similar paradigm of genetic polymorphism and individual cancer susceptibility in prostate and breast carcinogenesis. We are evaluating polymorphisms in the steroid 5α-reductase type II and androgen receptor genes in relation to prostate cancer based on the evidence that intracellular dihydrotestosterone is the critical “carcinogen.” We are pursuing genetic polymorphisms affecting estradiol metabolism, including those in the 17β-hydroxysteroid dehydrogenase 2 and estrogen receptor genes as they relate to susceptibility to breast cancer. The potential role of a polymorphism in the cytochrome P450c17α gene in both breast and prostate cancers is also being examined. J. Cell. Biochem. 25S:15-22. © 1997 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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