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  • Life and Medical Sciences  (77)
  • 1985-1989
  • 1980-1984  (77)
  • 1970-1974
  • 1960-1964
  • 1940-1944
  • 1982  (77)
Collection
Keywords
Publisher
Years
  • 1985-1989
  • 1980-1984  (77)
  • 1970-1974
  • 1960-1964
  • 1940-1944
Year
  • 11
    Electronic Resource
    Electronic Resource
    Measurement of blood-brain barrier permeation in rats during exposure to 2450-MHz microwaves (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 371-383 
    Details
    ISSN: 0197-8462
    Keywords: blood-brain barrier ; rats ; 2450-MHz microwaves ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Adult rats anesthesized with pentobarbital and injected intravenously with a mixture of [14C]sucrose and [3H]inulin were exposed for 30 min to an environment at an ambient temperature of 22, 30, or 40 °C, or were exposed at 22 °C to 2450-MHz CW microwave radiation at power densities of 0, 10, 20, or 30 mW/cm2. Following exposure, the brain was perfused and sectioned into eight regions, and the radioactivity in each region was counted. The data were analyzed by two methods. First, the data for each of the eight regions and for each of the two radioactive tracers were analyzed by regression analysis for a total of 16 analyses and Bonferroni's Inequality was applied to prevent false positive results from numerous analyses. By this conservative test, no statistically significant increase in permeation was found for either tracer in any brain region of rats exposed to microwaves. Second, a profile analysis was used to test for a general change in tracer uptake across all brain regions. Using this statistical method, a significant increase in permeation was found for sucrose but not for inulin. A correction factor was then derived from the warm-air experiments to correct for the increase in permeation of the brain associated with change in body temperature. This correction factor was applied to the data for the irradiated animals. After correcting the data for thermal effects of the microwave radiation, no significant increase in permeation was found.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030309
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  • 12
    Electronic Resource
    Electronic Resource
    A behavioral response of swine to a 60-Hz electric field (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 443-451 
    Details
    ISSN: 0197-8462
    Keywords: miniature swine ; ELF ; 60-Hz electric field ; behavior ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: It has been shown that rats, given the choice, will spend more time out of a 60-Hz electric field than in it at field strengths ≥ 75 kV/m. This paper describes research to examine the relevance of these data to a different species, the pig. Miniature pigs that had been exposed to a 60-Hz electric field at 30 kV/m for 20 h/day, 7 days/week for as long as 6 months, were tested for their preference for the presence or absence of the field during a 23.5-h period. Similar to earlier results with rats, miniature pigs spent more time out of the electric field than in it during the sleeping period.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030407
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  • 13
    Electronic Resource
    Electronic Resource
    Arterial retia related to supply of the central nervous system in two small toothed whales- narwhal (Monodon monoceros) an beluga (Delphinapterus leucas) (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 174 (1982), S. 41-56 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied the comparative anatomy of arterial plexuses (retia mirabilia) related to supply of the central nervous system in two closely related species of toothed whales - narwhal (Monodon monoceros) and beluga Delphinaterus leucas). In both species, retia originate from major vessels in the neck, thorax, and lumbar regions, then extend into the neural canal and cranium to supply the spinal cord and brain. The system generally consists of arteries embedded in á matrix of fatty connective tissue. Constituent vessels are only occasionally reated to veins or venous sinuses. Though retial anatomy is similar in the two species, there are two related features that appear species specific: (1) amount of retia originating from the supreme intercostal arteries and (2) thoracic retial size. Both are larger in the narwhal, as are values for hematocrit and hemoglobin concentration, which, in this study, we use as indices of diving ability. Our data are consistent with the hypothesis that the retia are in some way linked to diving ability. The nature of this link is not known; however, we discuss our results in the context of the most popular hyotheses of retial function.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051740105
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  • 14
    Electronic Resource
    Electronic Resource
    The structure of the chambered nautilus siphuncle: The siphuncular epithelium (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 5-22 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The siphuncle of the chambered nautilus (Nautilus macromphalus) is composed of a layer of columnar epithelial cells resting on a vascularized connective tissue base. The siphuncular epithelium taken from chambers that have not yet begun to be emptied of cameral liquid has a dense apical brush border. The great number of apical cell junctions (zonula adherens) compared to the number of nuclei suggests extensive interdigitation of these cells. The perinuclear cytoplasm of these preemptying cells is rich in rough endoplasmic reticulum. The siphuncular epithelium of both emptying and “old” siphuncle (which has already completed emptying its chamber) both show little rough endoplasmic reticulum but do contain extensive systems of mitochondria-lined infoldings of the basolateral plasma membranes. Active transport of NaCl into the extracellular space of this tubular system probably entrains the water transport involved in the chamber-emptying process. Both emptying and old siphuncular epithelium also show large basal infoldings (canaliculi) continuous with the hemocoel, which appear to be filled with hemocyanin. The apical cell junctions of emptying and old siphuncular epithelium contain septate desmosomes that may help to prevent back-flow of cameral liquid into the chambers.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051720103
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  • 15
    Electronic Resource
    Electronic Resource
    Structure and evolution of tetraodontoid teeth: An autoradiographic study (pisces, Tetraodontiformes) (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 171 (1982), S. 283-292 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: For years teeth of tetraodontoid fishes generally have been considered coalescent even though “coalescence,” which also is found in fishes of other families, has never been well defined. This paper deals with some aspects of coalescence of the teeth in tetraodontoids and attempts to define this condition. The sites of osteodentinogenesis and the mechanisms by which hard tissues are formed, reabsorbed, and abraded during feeding were analyzed from semiserial decalcified sections and from ground sections, as well as from autoradiographs of the premaxilla and dentary bones of Sphoeroides greeleyi. The observations reported here, taken together with other data we have obtained on members of the Tetraodontoidei, permit clear definitions of “tooth” and “supporting bone,” and consequently the structural meaning of coalescence. From these data we hypothesize how coalesced masticatory structures may have evolved in this group.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051710304
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  • 16
    Electronic Resource
    Electronic Resource
    Architecture of the hind limb muscles of cats: Functional significance (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 173 (1982), S. 185-195 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Force, velocity, and displacement properties of a muscle are determined in large part by its architectural design. The relative effect of muscle architecture on these physiological variables was studied by determining muscle weight, fiber length, average sarcomere length, and approximate angle of pinnation for 24 cat hind limb muscles. Muscle lengths ranged from 28.3 to 144 mm, whereas fiber lengths ranged from 8.4 to 105.5 mm. Generally, fiber to muscle length ratios were similar throughout a muscle. Estimated angles of pinnation of muscle fibers varied from 0 to 21° with most having an angle of less than 10°. The cross-sectional area of the knee extensors was similar to the knee flexors (16.43 vs. 16.83 cm2) whereas the cross-sectional area of the ankle extensors was more than six times greater than the ankle flexors (18.59 vs. 2.83 cm2). There was a 6.7-fold difference in the maximal force between muscles, when normalized to a constant weight, that could be attributed to architectural features. Rations of wet weight to predicted maximal tetanic tension for each muscle and group were calculated to compare the relative priority of muscle force versus muscle length-velocity for a given mass of muscle. These ratios varied from 0.4 to 4.84. The ratios suggest that velocity and/or displacement is a priority for the hamstrings, whereas force is a priority for the quadriceps and lower leg muscles. As much as a 12.6-fold difference in maximal velocity between muscles can be attributed to differences in fiber lengths. This can be compared to approximately a 2.5-fold difference in maximal velocity reported to occur as a result of biochemical (intrinsic) differences.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051730206
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  • 17
    Electronic Resource
    Electronic Resource
    Cerebellar afferents to paramedian lobule from the trigeminal complex in Tupaia glis: A horseradish peroxidase (HRP) study (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 209-222 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Projections from the trigeminal complex to paramedian lobule (PML) were studied in the tree shrew (Tupaia glis) by means of retrograde transport of horseradish peroxidase (HRP). Neurons which project to both dorsal and ventral folia of PML are located primarily in those areas of the trigeminal nuclear complex interpreted as nucleus interpolaris (Vi) and caudal areas of the nucleus oralis (Vo). The majority of HRP-labeled neurons lie in ventral and ventrolateral regions of Vi/Vo. No HRP-reactive cells are present in the principal (Vp), mesencephalic, or motor nuclei nor in nucleus caudalis or rostral portions of oralis. The majority of trigeminocerebellar (TC) cells are found in ipsilateral Vi; however, sparse numbers of labeled somata are present in this subnucleus on the contralateral side. Within Vi/Vo, small fusiform and medium- and large-sized multipolar neurons contain HRP-reaction product. Large multipolar cells are found primarily in ventrolateral portions of Vi/Vo, while medium and small neurons are scattered throughout the ventral half of the nucleus. Small-sized neurons are also present dorsally within Vi/Vo. Axons of labeled TC cells course laterally through the spinal trigeminal tract, enter medial aspects of the restiform body, and arch dorsally into the cerebellum.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051720207
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  • 18
    Electronic Resource
    Electronic Resource
    Comparative aspects of brain organization of an african “wave” electric fish, Gymnarchus niloticus (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 174 (1982), S. 313-334 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Gymnarchus niloticus, one of the less-well-known electroreceptive teleost fishes, is the only African mormyriform fish with a wavelike or tone electric organ discharge. For Gymnarchus, this is the first detailed description of the lateral line lobe, vestibulolateral lobe, cerebellum, and midbrain torus semicircularis - central electrosensory structures. Brain organization in Gymnarchus closely resembles that of mormyrids. In particular, the lateral line lobe is a bilateral structure with three cortical zones - ventral, dorsal, medial - and a fourth central zone of large cells. The convergent evolution of the electric sense of mormyriform and gymnotoid fish, and its central representation, is discussed.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051740306
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  • 19
    Electronic Resource
    Electronic Resource
    A calcium- and pH-regulated actin binding protein from D. discoideum (1982)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 287-308 
    Details
    ISSN: 0886-1544
    Keywords: actin-binding protein ; Dictyostelium ; cytoskeleton ; amoeboid movement ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protein from Dictyostelium discoideum with an apparent subunit molecular weight of 95,000 daltons (95K protein) was previously identified as an actin-binding protein ‘Hellewell and Taylor, 1979’. In this paper, we present a method for purifying the protein, and characterize some important aspects of its structure and function. Purification of the 95K protein is achieved by fractionation with ammonium sulfate followed by chromatography on DEAE-cellulose, gel filtration on 6% agarose, and final purification on hydroxyapatite. The 95K protein is a dimer, composed of apparently identical subunits. It is a rod-shaped molecule, 38 nm in length, with a Stokes radius of 74 Å. In these structural properties, the 95K protein is similar to muscle and nonmuscle α-actinins. The 95K protein and filamin are equally competent, when compared on a weight basis, to enhance the apparent viscosity of actin as determined by falling ball viscometry. The apparent viscosity of mixtures of the 95K protein and actin is dramatically reduced at pH greater than 7.0 or free ‘Ca2+’ greater than 10-7 M. We also examine the mechanism by which calcium regulates the interaction of the 95K protein and actin. A change in free ‘Ca2+’ induces no detectable change in the quaternary structure of the 95K protein. Our experiments indicate that the 95K protein does not dramatically alter the length distribution of actin filaments in the presence of micromolar free ‘Ca2+’. A large fraction of the 95K protein cosediments with actin in the presence of low free ‘Ca2+’ (ca. 3 × 10-8M), but not in the presence of high free ‘Ca2+’ (ca. 4 × 10-6M). We conclude that increased free ‘Ca2+’ inhibits gelation of actin by the 95K protein by reducing the affinity of the 95K protein for actin. We propose that 95K protein is an important component of the cytoskeletal/contractile system in D. discoideum amoebae.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970020308
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  • 20
    Electronic Resource
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    Binding stoichiometry of 21S dynein to A and B subfiber microtubules (1982)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 429-443 
    Details
    ISSN: 0886-1544
    Keywords: 21S dynein ; tubulin ; binding stoichiometry ; ATP sensitivity ; binding cooperativity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The binding properties of Tetrahymena 21S dynein to doublet A and B subfiber microtubules were analyzed by both a turbidimetric assay (Δ A350 nm) and electron microscopy. KCl-extracted, sucrose-gradient, purified 21S dynein binds to each of the two kinds of axonemal microtubules in both ATP-insensitive and ATP-sensitive modes, even though only a single type of binding occurs to each of the subfibers in situ. Total dynein bound to axonemal microtubules is a composite of binding that is sensitive to dissociation by ATP and binding that is insensitive to ATP. Each exhibits a different binding profile. Total binding exhibits a sigmoid profile (h = 1.93) and saturates at 1.49 mg D/mg T. ATP-sensitive binding likewise exhibits a sigmoid profile (h = 2.66) but saturates at 1.06 mg D/mg T. Binding occurs with a similar affinity for both A and B subfibers. The Hill coefficient (h) for ATP-sensitive binding implies positive cooperativity between binding events. ATP-insensitive binding was studied independently in 20 μM ATP, 10 μM vanadate, which blocks ATP-sensitive binding. ATP-insensitive binding exhibits a hyperbolic profile (h = 1.0) and likewise occurs along each of the two kinds of axonemal tubules. Binding saturates at 0.87 mg D/mg T. The binding data suggest that the tubulin dimer has conserved both ATP-sensitive and ATP-insensitive binding sites for 21S dynein, even though the sites may not be expressed in vivo.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970020503
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