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  • Life and Medical Sciences  (47)
  • Wiley-Blackwell  (47)
  • Periodicals Archive Online (PAO)
  • 1980-1984  (47)
  • 1
    Electronic Resource
    Electronic Resource
    Comparative study of the forelimbs of the semifossorial prairie dog, Cynomys gunnisoni, and the scansorial fox squirrel, Sciurus nlger (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 55-68 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparative study of the forelimbs of the semifossorial prairie dog, Cynomys gunnisoni, and the scansorial tree squirrel, Sciurus niger, was focused on the musculoskeletal design for digging in the former and climbing in the latter. Based on lever arm mechanics, it was expected that the forelimb of the prairie dog would show features appropriate to the production of relatively large forces and that of the fox squirrel to relatively great velocity. Force and lever arm measurements were made of select forelimb muscles at the shoulder, elbow, and wrist joints for a series of angles in both species. Contraction time and fatigue indexes were determined for the same forelimb muscles. Contrary to expectation, in the few cases in which significant (P 〈 .05) differences were found, the forces, lever arms, and torques (force times its lever arm) were greater in the smaller fox squirrel. The observed variation in the torques produced fits the demands on the forelimb during climbing and digging as estimated from films. Several forelimb muscles of the fox squirrel show significantly higher mean contraction times than do the homologous muscles of the prairie dog. There were no significant differences between the two species in the fatigability of the selected forelimb muscles, although the mean fatigue index was always higher (less fatigable muscle) in the prairie dog. Similarities in the forelimbs of these two sciurids suggest that only minor modifications may have been required of the ancestral forelimb in order for descendent forms to operate successfully as climbers and diggers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051800107
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  • 2
    Electronic Resource
    Electronic Resource
    Size and shape of the mandibular condyle in primates (1983)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 177 (1983), S. 59-68 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationships between the size of the articular surface of the mandibular condyle and masticatory muscle size, tooth size, diet, and biomechanical variables associated with mastication were studied by taking 12 measurements on skulls of 253 adult female anthropoid primates, including three to ten specimens from each of 32 species.In regressions of condylar length, width, or area against body weight, logarithmic transformations substantially improve the fit of the equations compared with untransformed data. There is a strong relationship betwden condylar measurements and body weight, with all correlations being .94 or higher. The slopes of the allometric regressions of length, width, and area of the condylar head indicate slight positive allometry with body size.Folivorous primates have smaller condyles than frugivorous primates, and colobines have smaller condyles than cebids, cercopithecines, or hominoids. When colobines are eliminated, the differences between frugivores and folivores are not significant. However, the two species with the relatively largest condyles are Pongo pygmaeus and Cercocebus torquatus, suggesting that there may be a relationship between unusually large condylar dimensions and the ability to crak hard nuts between the teeth.Cranial features having strong positive correlations with condylar dimensions include facial prognathism, maxillary incisor size, maxillar postcanine area, mandibular ramus breadth, and temporal fossa area. These data are interpreted as indicating that relatively large condyles are associated with relatively large masticatory muscles, relatively inefficient mandibular biomechanics, and a large dentition. These relationships support the growing evidence that the temporomandibular joint is a stress-bearing joint in normal function.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051770106
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  • 3
    Electronic Resource
    Electronic Resource
    An electromyographic study of the function of the jaw adducting muscles in Varanus exanthematicus (varanidae) (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 173 (1982), S. 137-158 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The function of major features of the skull of Varanus exanthematicus during feeding was examined using cineradiography and electromyography. During the initial stages of feeding, Varanus grabs and orients a prey item in the mouth with no mastication, tearing of the prey, or killing bite. Ingestion is through a highly stereotyped movement, inertial feeding. The tongue plays no role in food transport. Once the prey is in the pharyngeal region, the hyoid apparatus squeezes the prey into the esophagus and stomach. Activity of jaw adducting muscles during prey orientation and inertial feeding is strikingly different. In prey orientation, the adductor musculature is active over long periods, and intermuscular differentiation and unilateral activity are common. During these phases the musculature is producing force against the resistance of the prey item held between the teeth. In inertial feeding, the jaw musculature functions to close the jaws rapidly against little resistance. A consistent pattern of intramuscular differentiation is present, with some portions of the musculature being active during both jaw opening and closing. Activity of the Mm. adductor mandibulae externus and pterygoideus is indistinguishable. Neither meso- nor metakinetic movement was observed during inertial feeding; resolution of interacranial movement was less certain during power phases. The quadrate moved during jaw opening and closing in inertial feeding. However, its movement was not linked with that of the palatomaxillary segment. These data are discussed in three contexts: cranial kinesis, intramuscular differentiation, and the mechanics of whole muscles.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051730203
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  • 4
    Electronic Resource
    Electronic Resource
    Concepts of epithelial-mesenchymal interactions during development: Tooth and lung organogenesis (1984)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 26 (1984), S. 117-125 
    Details
    ISSN: 0730-2312
    Keywords: gene expression ; amelogenins ; cDNA ; type II cells ; pulmonary surfactant ; ameloblasts ; epithelial differentiation ; regional mesenchymal specificity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: One of the major problems in developmental biology concerns how differential gene activity is regionally controlled. One approach to this problem is the use of mesenchyme specification of epithelial-specific gene expression, such as, during tooth morphogenesis or lung morphogenesis. In the example of tooth morphogenesis, dental papilla ectomcsenchyme induces de novo gene expression as assayed by detection of amelogenin transcripts, or immunodetection of amelogenin poly-peptidcs within ameloblast cells. This process does not require serum supplementation or exogenous factors during epithelial-mesenchymal interactions in vitro. In contrast, lung morphogenesis requires hormones to mediate mesenchyme-derived influences upon type II epithelial cell differentiation and the production of pulmonary surfactant (eg, neutral and phospholipids, surfactant proteins). Glucocorticoids are required to stimulate the release of fetal pneumonocyte factor (FPF) from fibroblasts which, in turn, enhance the production of pulmonary surfactant. Thy-roxin appears to regulate the relative responsiveness of progenitor type II cells to steroid-stimulated release of FPF. This review will highlight key concepts associated with these developing organ systems and emphasize the problem of regional controls which regulate epithelial cell-specific gene activity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240260207
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  • 5
    Electronic Resource
    Electronic Resource
    Oncogenes: Growth regulation and the papovaviruses polyoma and SV40 (1984)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 26 (1984), S. 83-93 
    Details
    ISSN: 0730-2312
    Keywords: DNA binding protein ; polyoma virus ; moddle-T ; retroviruses ; oncogenes ; transforming proteins ; SV40 large-T ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cellular oncogenes and their activated and retrovirus-coded counterparts play an important role in cellular regulation. Here the relationship between such oncogenes and the genes coding for the transforming proteins of the papovaviruses, polyoma viruses, and simian virus 40 (SV40) is discussed. It is concluded that polyoma virus may transform established cells by a mechanism involving activation of a cellular oncogene product, whereas SV40 may transform by a mechanism involving a previously little studied cytoplasmic form of the transforming protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240260204
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  • 6
    Electronic Resource
    Electronic Resource
    Repair Responses to DNA Damage: Enzymatic Pathways in E coli and Human Cells (1982)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 18 (1982), S. 271-283 
    Details
    ISSN: 0730-2312
    Keywords: E coli ; DNA damage ; excision repair ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Bacteria and eukaryotic cells employ a variety of enzymatic pathways to remove damage from DNA or to lessen its impact upon cellular functions. Most of these processes were discovered in Escherichia coli and have been most extensively analyzed in this organism because suitable mutants have been isolated and characterized. Analogous pathways have been inferred to exist in mammalian cells from the presence of enzyme activities similar to those known to be involved in repair in bacteria, from the analysis of events in cells treated with DNA damaging agents, and from the analysis of the few naturally occurring mutant cell types.Excision repair of pyrimidine dimers produced by UV in E coli is initiated by an incision event catalyzed by a complex composed of uvrA, uvrB, and uvrC gene products. Multiple exonuclease and polymerase activities are available for the subsequent excision and resynthesis steps. In addition to the constitutive pathway, which produces short patches of 20-30 nucleotides, an inducible excision repair process exists that produces much longer patches. This long patch pathway is controlled by the recA-lexA regulatory circuit and also requires the recF gene. It is apparently not responsible for UV-induced mutagenesis. However, the ability to perform inducible long patch repair correlates with enhanced bacterial survival and with a major component of the Weigle reactivation of bacteriophage with double-strand DNA genomes.Mammalian cells possess an excision repair pathway similar to the constitutive pathway in E coli. Although not as well understood, the incision event is at least as complex, and repair resynthesis produces patches of about the same size as the constitutive short patches. In mammalian cells, no patches comparable in size to those produced by the inducible pathway of E coli are observed.Repair in mammalian cells may be more complicated than in bacteria because of the structure of chromatin, which can affect both the distribution of DNA damage and its accessibility to repair enzymes. A coordinated alteration and reassembly of chromatin at sites of repair may be required. We have observed that the sensitivity of digestion by staphylococcal nuclease (SN) of newly synthesized repair patches resulting from excision of furocoumarin adducts changes with time in the same way as that of patches resulting from excision of pyrimidine dimers. Since furocoumarin adducts are formed only in the SN-sensitive linker DNA between nucleosome cores, this suggests that after repair resynthesis is completed, the nucleosome cores in the region of the repair event do not return exactly to their original positions.We have also studied excision repair of UV and chemical damage in the highly repeated 172 base pair α DNA sequence in African green monkey cells. In UV irradiated cells, the rate and extent of repair resynthesis in this sequence is similar to that in bulk DNA. However, in cells containing furocoumarin adducts, repair resynthesis in α DNA is only about 30% of that in bulk DNA. Since the frequency of adducts does not seem to be reduced in α DNA, it appears that certain adducts in this unique DNA may be less accessible to repair.Endonuclease V of bacteriophage T4 incises DNA at pyrimidine dimers by cleaving first the glycosylic bond between deoxyribose and the 5′ pyrimidine of the dimer and then the phosphodiester bond between the two pyrimidines. We have cloned the gene (denV) that codes for this enzyme and have demonstrated its expression in uvrA recA and uvrB recA cells of E coli. Because T4 endonuclease V can alleviate the excision repair deficiency of xeroderma pigmentosum when added to permeabilized cells or to isolated nuclei after UV irradiation, the cloned denV gene may ultimately be of value for analyzing DNA repair pathways in cultured human cells.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.1982.240180303
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  • 7
    Electronic Resource
    Electronic Resource
    The larval nephridia of the brackish-water polychaete, Nereis diversicolor (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 273-289 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The larval nephridia of the brackish-water polychaete Nereis diversicolor are described for the first time, and have been studied to determine if their times of development and structural characteristics are consistent with a role in the osmotic regulation of the larva. As shown in serial paraffin sections and by interference-contrast optics, the nephridia of the three-setiger larva consist of a single pair of very large metanephridia, arising in the 3rd larval setiger, but with their elongated terminal ducts and coiled ciliated tubules pushed forward into the 2nd setiger; their open metanephrostomes and anterior anchoring filaments lie dorsal to the 2nd set of setae. In contrast, the definitive or juvenile metanephridia, arising in the 4th and subsequently formed setigerous segments, have short terminal ducts and coiled ciliated tubules confined to the segments on which their external nephropores open; their nephrostomes are ventrally located and open into the rear of the next anterior segment. These findings are in contrast to the claims of Edouard Meyer (1887), who described two pairs of closed protonephridia in the 2nd and 3rd larval setigers of Perinereis cultrifera. Although it is not excluded that the single larval pair of metanephridia of N. diversicolor may arise as protonephridia, Meyer's claim of two pairs of larval protonephridia was an observational error. The larval nephridia of the marine Platynereis dumerilii resemble in form, but are considerably smaller than, those of N. diversicolor. It is concluded that the hypertrophied pair of larval metanephridia of N. diversicolor is an evolutionary adaptation to existence in habitats of low and unpredictably varying salinity. Their development occurs irrespective of the prevailing salinity; hence, it must be genetically determined.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051790306
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  • 8
    Electronic Resource
    Electronic Resource
    In vitro proliferation and lifespan of bovine aorta endothelial cells: Effect of culture conditions and fibroblast growth factor (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 103 (1980), S. 385-392 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of culture conditions on calf dorsal aorta endothelial cells was studied. Population doubling time varied as a function of the cell seeding density, growth medium, serum supplement, and concentration of fibroblast growth factor (FGF). The shortest population doubling time was found for cells (population doubling level 0-30) grown in Eagle's Minimal Essential Medium (MEM) supplemented with 10% fetal bovine serum (FBS) and 100 ng/ml FGF. The stimulatory effect of FGF on bovine endothelial cell proliferation was dependent on cell inoculation density. FGF significantly increased cell division rate at cell inocula less than 1 ± 104 cells/cm2 but not at higher densities. The population doubling time and cell size increased as the mass culture population doubling level increased. The replicative lifespans of bovine endothelial cells grown in medium supplemented with 20% FBS were 10-15% greater than parallel cultures supplemented with 10% FBS. Cultures grown in medium supplemented with 10% FBS and 50 ng/ml FGF showed a 50% increase in replicative lifespan compared to cultures grown in medium supplemented with 10% FBS alone. When FGF was used the increase in the number of doublings was a function of the length of time the cells were grown in the presence of FGF. This report extends comparable observations on the in vitro aging of human diploid fibroblasts to bovine endothelial cells.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041030303
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  • 9
    Electronic Resource
    Electronic Resource
    The membrane potential of Ehrlich ascites tumor cells: An evaluation of the null point method (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 106 (1981), S. 399-406 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of valinomycin (25 pM) on the membrane potential and on initial, passive Na+ and K+ movements have been determined in Ehrlich ascites tumor cells. The membrane potential of steady-state cells in a physiologic environment was - 23.2 mV. Addition of valinomycin induced a small, significant hyperpolarization (Vm = -29.6 mV) when averaged over the population tested. However, analyses of the response of individual cells to valinomycin showed two different potential effects: (1) the majority of cells hyperpolarized after treatment; but (2) a significant fraction depolarized when exposed to valinomycin. The Vm of steady-state cells incubated in saline with K+ at concentrations of 21 mM or 75 mM was - 21.4 mV and -22.0 mV, respectively. Addition of valinomycin to these cells was without effect on Vm, thus establishing the “null point” responses. Only for cells incubated in saline with a K+ of 75 mM was there agreement between Vm and K+ equilibrium potential (Vk). Determinations of cellular Na+ and K+ showed that valinomycin induced net losses of K+ and gains of Na+ by cells incubated in either physiologic saline or saline with a K+ concentration of 21 mM. However, the celular K+ of cells incubated in saline with a K+ concentration of 75 mM was unaltered by valinomycin. There was a two- to threefold increase in K+ permeability of the cell membrane in the presence of valinomycin. These results are consistent with the existence of two null points in the membrane-potential response to valinomycin: One is established when the membrane potential corresponds to Vk; the second occurs when the effects of valinomycin on K+ loss from the cell are exactly offset by its inhibition of active Na+ + K+ transport.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041060309
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  • 10
    Electronic Resource
    Electronic Resource
    Variable coupling of active NA+ + K+ transport in Ehrlich ascites tumor cells: Regulation by external NA+ and K+ (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 106 (1981), S. 407-418 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of altered external sodium and potassium concentrations on steady state, active Na+ + K+ transport in Ehrlich ascites tumor cells have been investigated. Membrane permeability to Na+ and K+, intracellular [Na+] and [K+], and membrane potential were measured. Active cation fluxes were calculated as equal and membrane potential were measured. Active cation fluxes were calculated as equal and opposite to the net, diffusional leak fluxes. Elevation of external K+ (6-60 Mm)by equivalent replacement of Na+ (154-91 mM) inhibits both active Na+ and K+ fluxes, but not proportionally. This results in a decrease of the coupling ratio (rp = -Jkp/JpNa) as external K+ is increased. Elevation of external K+ (3-68 mM) at constant Na+ (92mM) inbibits Jpk, but is without effect on JpNa. The coupling ratio declines from 1.01 ± 0.14 to 0.07 ± 0.05, a 14-fold alteration. Reduction of external Na+ (154-25 mM) at constant K+ (6mM) depresses JpNa, but is without effect on Jpk. The coupling ratio increases from 0.63 ± 0.04 at 154 mM Na+ to 4.5 ± 2.04 at 25 mM Na+. The results of this investigation are consistent with the independent regulation of active cation fluxes by the transported species. Kinetic analysis of the data indicates that elevation of external sodium stimulates active sodium efflux by interacting at “modifier sites” at the outer cell surface. Similarly, external potassium inhibits active potassium influx by interaction at separate modifier sites.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041060310
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