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Y Yeh

Publications and source records attributed to Y Yeh.

At least 55 records · Page 3Linked to original sources
PubMed1988

Observations on electrophysiologically characterized receptive fields of thin testicular afferent axons: a preliminary note on the analysis of fine structural specializations of polymodal receptors.

The sparse distribution of thin, principally unmyelinated sensory axons confined largely to the planar tunica vasculosa of the testis provides a suitable model for examining the fine structure of electrophysiologically characterized nerve fiber terminals. The marked sites of polymodal receptors of canine testis using the in vitro preparation devised by Kumazawa et al. (1987) were examined in serial sections traced to the terminal with the electron microscope, revealing the first micrographs of a characterized polymodal receptor ending. The inferred role of these terminals in nociception, their organelle content, and the problems encountered in interpreting our initial findings are considered in the context of the variety of morphological patterns and functional roles of thin sensory axons.

Animals↗
PubMed1987

Optical ellipsometry on the diffraction order of skinned fibers. pH-induced rigor effects.

The polarization properties of light diffracted from single-skinned fibers of skeletal muscles have been examined under conditions in which the bathing solution pH and the ionic strength are changed. For fibers in the relaxed state, we observe large decreases in both the total depolarization signal, r, and the total diffraction birefringence signal, delta nT, upon pH change from 7.0 to 8.0 at normal ionic strength. However, if the ionic strength is raised, then the r-value change as the pH changes from pH 7.0 to pH 8.0 is much smaller. If the rigor state is achieved at pH 8.0, and 0 mM ATP under either of the ionic strength conditions, the fiber can still be stretched. Rigor stiffness for this state is only approximately 20% that of the value of the stiffness at pH 7.0 rigor. Electron micrographs obtained under this pH 8.0 rigor state show that the overlap region can be decreased upon stretching the fiber, signifying a different kind of weaker-binding rigor state. Optically, the weaker-binding rigor state has a lower depolarization signal and larger form birefringence than the strong-binding rigor state. To convert from one type of rigor state (pH 7.0) to the other rigor state (pH 8.0), or vice versa, the fiber must first be relaxed. Apparently, either of the rigor states can block the full impact of the pH effect.

Animals↗
PubMed1986

A kinetic description of antifreeze glycoprotein activity.

The antifreeze glycoproteins (AFGP) of polar fish have the ability to depress the freezing temperature of water approximately 500 times the amount expected based on the number of AFGP molecules in solution; yet AFGP solutions have a purely colligative melting point depression. The difference of solution melting and freezing temperatures is the antifreeze activity of AFGP. One characteristic of AFGP activity that requires further examination is the effect of concentration on antifreeze activity, especially whether the activity saturates at high concentrations or the measured activity increases ad infinitum. This study first surveys the activity of the various antifreeze components from both Pagothenia borchgrevinki and the Arg-containing antifreeze glycoprotein from Eleginus gracilis (EgAF). It was found that all AFGP components examined have a plateau in activity at high concentration, but the actual value of the plateau activity differs between the different length AFGP components and between AFGP and EgAF. While the low molecular weight components of both AFGP and EgAF lose activity at deep supercooling, at high concentration activity is restored. The activity data is then shown to fit a reversible kinetic model of AFGP activity, and the coefficients obtained are used to compare the activity differences between AFGP components and between AFGP and EgAF. The model is also shown to describe the activity of the antifreeze protein of the fish Pseudopleuronectes americanus and the thermal hysteresis protein of the insect, Tenebrio molitor.

Animals↗
PubMed1986

Optical depolarization changes in single, skinned muscle fibers. Evidence for cross-bridge involvement.

Optical ellipsometry studies of single, skinned muscle fibers conducted on the diffraction orders have yielded spectra that are sensitive to the state of the fiber. The linearly polarized light field vector becomes elliptically polarized as it passes through the fiber and may be collected at the diffraction orders. Fibers that have been subjected to extraction of myosin (0.6 M KCl) retain a weak diffraction pattern and exhibit a substantially decreased depolarization of incident linearly polarized light. A significant decrease in polarization is seen in skinned fibers that are subject to an increase in pH from 7.0 to 8.0. This increase in pH results in a decrease of approximately 30% in the depolarization angle of single fibers. The major decrease in depolarization angle that we observe at pH 8.0 is consistent with the notion that as cross-bridges move out from the shaft of the thick filament, their ability to cause depolarization of the incident linearly polarized light decreases. This interpretation is also consistent with the work of Ueno and Harrington where the decrease in the ability to cross-link S-1 and S-2 to the thick filament at pH 8.2 suggests cross-bridge movement away from the thick filament. A large decrease in birefringence, seen after treatment of skinned fibers with alpha-chymotrypsin, appears to be related to the breakdown of myosin into rod, S-1, heavy meromyosin, and light meromyosin.

Adenosine Triphosphate↗
PubMed1986

Antifreeze glycoproteins from polar fish blood.

Existing experimental evidence strongly suggests that the mechanism of activity of the Antarctic AFGP molecules is the inhibition of ice growth by competitive adsorption onto the growth sites of ice. The data further suggest the blocking of the formation of large critical nuclei for ice growth. Experiments showing that the longer polymers (AFGP 1-5) have different growth-prevention properties with different types of ice than the shorter polymers (AFGP 6-8) provide additional evidence that crystal size and habits are linked to function. Four main observations have been used in AFGP studies: (a) The ice crystal habit (size) affects the activity, (b) AFGP is on the surface of ice crystals, as shown by surface second harmonic generation (SSHG), (c) the presence of AFGP lowers the surface energy at the ice-solution interface, and (d) kinetic calculations of the inhibition of ice-crystal growth fit adsorption isotherms. In particular, AFGP 4 fits a Langmuirian adsorption curve. On the detailed mechanistic side, there is a need to quantify the competitive rates of water-molecule attachment to ice as well as the rates of adsorption-desorption of AFGP on the ice surface. Toward this end, experiments are currently being conducted to examine the differential growth rates of ice crystals freely growing into a solution of AFGP. Direct observation of the adsorption and desorption of AFGP on the ice surface is possible in principle using the SSHG technique. A nonperturbative probe method that can differentiate adsorbed AFGP from the solution phase molecules is needed. Finally, a mechanistic description of molecular function is never complete unless the detailed molecular binding to the surface is elucidated. This task has not been accomplished yet, and thus there is still a question as to which molecular group is actually adsorbed onto the surface and for how long. Theoretically, as we have seen, the departure from Langmuirian adsorption is pronounced for small AFGP molecules under certain conditions. More refinements of the ideas of intermolecular or intramolecular cooperative interaction of AFGP on the ice surface are needed.

Adsorption↗
PubMed1985

Depolarization spectrum of diffracted light from muscle fiber. The intrinsic anisotropy component.

The depolarization signal of the diffraction patterns from muscle fibers includes information that differs from that of transmission birefringence experiments. Although both the birefringence studies and the phase shift studies of Yeh et al. (Yeh, Y, and G. Pinsky, 1983, Biophys. J., 42:83-90; Yeh, Y., M. E. Corcoran, R. J. Baskin, and R. L. Lieber, 1983, Biophys. J., 44:343-351) include inseparable intrinsic and form contributions, the present analysis shows that the magnitude of the E-field components of diffracted light is affected only by the intrinsic contribution. We have analyzed the amplitude portion of the data of which the phase shift portion had previously been reported (Yeh, Y., M. E. Corcoran, R. J. Baskin, and R. L. Lieber, 1983, Biophys. J., 44:343-351). For the relaxed-to-rigor transition, these field amplitudes also exhibit changes when ATP concentration is decreased. The observed decrease in optical depolarization upon rigor is consistent with the idea that optically anisotropic elements move away from the myosin thick filament under such conditions.

Adenosine Triphosphate↗
PubMed1985

Thin-fiber cutaneous innervation and its intraepidermal contribution studied by labeling methods and neurotoxin treatment in rats.

Sensory nerves innervating rat distal limb skin were labeled by axonal transport of an enzyme-lectin conjugate injected into lumbar dorsal root ganglia (DRG), with emphasis on tracing the course of the thin axons. Selective neonatal neurotoxin destruction of most unmyelinated sensory or sympathetic axons was achieved by treatment with capsaicin (CAP) and 6-hydroxydopamine (6-OHDA), respectively. The relationship of substance P-immunoreactive (SPI) axons to the patterns of axonal transport-labeled thin axons was compared in normal and neurotoxin-treated animals. SPI is restricted to a limited population of unmyelinated axons, and electron-microscopic observation reveals its total absence in myelinated axons. SPI fibers of sensory origin, as determined by CAP susceptibility, can be traced into the epidermal stratum spinosum, in relation to guard hair follicles, mast cells, and a specific class of small blood vessels. These morphological features are not eliminated by neurotoxin sympathectomy, and some are inferred to contribute to the initial events associated with the neurogenic vasodilation and plasma extravasation associated with the inflammatory response. A re-evaluation of the concept of "free nerve endings" is suggested in the context of the variety of afferent and efferent patterns displayed by sensory peptidergic unmyelinated axons, their putative nociceptive role, and the functional diversity of sensory C fibers.

Animals↗
PubMed1984

Conformation of the antifreeze glycoprotein of polar fish.

High-field proton and 13C NMR spectroscopy has been used to test and refine the recent proposal, based on vacuum uv circular dichroism results, of a threefold left-handed helical conformation for antifreeze glycoprotein (AFGP). Partial assignment of the protons of the glycotripeptide repeating unit has been made by comparison with spectra of model compounds, by selective decoupling, and by measurements of nuclear Overhauser effect (nOe). At 40 degrees C, AFGP fraction 8 (Mr 2600) shows 2-Hz linewidths which broaden at lower temperature. Neither 1H nor 13C chemical shifts depend strongly on temperature, suggesting no abrupt conformational transition. The nOe between alanine alpha and beta protons vary with temperature and with field strength, from small positive enhancements at 50 degrees C and 80 MHz to large negative effects at 3 degrees C and 300 MHz, indicating a substantial change of rotational correlation time with temperature. The higher-molecular-weight fraction 1-4 shows negative nOe at all temperatures. The CD spectra of fraction 1-4 show bands characteristic of the polyproline II structure at both 3 and 50 degrees C, while those bands in fraction 8 are weaker at 50 than 3 degrees C. The 1H nOe, the 13C T1, and CD data are interpreted as indicating that AFGP fraction 8 is an extended "rod-like" conformation at low temperature which becomes a flexible coil at high temperature, while fraction 1-4 is a flexible rod with sufficient segmental mobility to eliminate any long-range order.

Animals↗
PubMed1984

Sarcomere length determination using laser diffraction. Effect of beam and fiber diameter.

An experimental and theoretical analysis is presented involving the effect of variation in fiber and beam diameter upon the determination of average sarcomere length in isolated single muscle fibers using laser light diffraction. The muscle diffraction phenomenon is simplified by first considering diffraction order position and intensity to be the result of grating and Bragg diffraction. It is the product of the intensity profiles, which results from these types of diffraction, that produces the diffracted order. These simplifying assumptions are then extended to the case of the real muscle. Based on these considerations and the theory that we recently presented, conditions are set forth under which grating information (i.e., sarcomere length) can be maximally expressed to yield accurate average sarcomere length values.

Animals↗
PubMed1984

Fine structure of subepithelial "free" and corpuscular trigeminal nerve endings in anterior hard palate of the rat.

Axonally transported protein labeled many trigeminal nerve endings in subepithelial regions of the anterior hard palate of the rat. Sensory endings were most numerous in the lamina propria near the tips of the palatal rugae where large connective tissue and epithelial papillae interdigitated. Two kinds of sensory ending were found there: "free" endings, and a variety of corpuscular endings. The "free" sensory endings consisted of bundles of unmyelinated axons separated from the connective tissue by relatively unspecialized Schwann cells covering part or all of their surface and a completely continuous basal lamina; they were commonly found running parallel to the epithelium or near corpuscular endings. The corpuscular sensory endings all had a specialized nerve form, specialized Schwann cells, and axonal fingers projecting into the corpuscular basal lamina or connective tissue. There were at least four distinct types of corpuscular ending: Ruffini-like endings were found among dense collagen bundles, and they had a flattened nerve ending with a flattened Schwann lamella on either side. Meissner endings had an ordered stack of flattened nerve terminals with flattened Schwann cells and much basal lamina within and around the corpuscle. Simple corpuscles were single nerve endings surrounded by several layers of concentric lamellar Schwann processes. Glomerular endings were found in lamina propria papillae or encircling epithelial papillae; they were a tangle of varied neural forms each of which had apposed flattened Schwann cells, and a layer of basal lamina of varied thickness. Fibroblasts often formed incomplete partitions around Meissner and simple corpuscles. The axoplasm of all kinds of subepithelial sensory endings contained numerous mitochondria and vesicles, as well as occasional multivesicular bodies and lysosomes; the axoplasm of all endings was pale with few microtubules and neurofilaments. The specialized lamellar Schwann cells had much pinocytotic activity. Four kinds of junctions were found between the corpuscular sensory endings and the lamellar Schwann cells: (1) symmetric densities that resemble desmosomes; (2) asymmetric densities with either the neuronal or glial membrane more dense; (3) neural membrane densities adjacent to Schwann parallel inner and outer membrane densities; and (4) sites of apparent Schwann endocytosis associated with neural blebs. The "free" sensory endings only made occasional desmosome-like junctions with their Schwann cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Fine-structural characterization of the somatic innervation of the tympanic membrane in normal, sympathectomized, and neurotoxin-denervated rats.

The pars tensa of the rat tympanic membrane (TM) consists largely of a lamina propria of specialized unbanded collagen bounded on the outer surface by an unusually thin epidermal layer and on the inner surface by a flat, single-cell mucosal layer. The mucosal layer is innervated solely by unmyelinated (C) axons, whereas the cutaneous layer is supplied by both myelinated and C axons. The outer surface differs from general body skin, lacking dermal papillae, hairs, sweat glands, and distinctive dermal corpuscular structures. Epidermal innervation includes distinctive terminals in the basal layer, unassociated with Merkel cells, and deeper intraepidermal smaller endings containing accumulations of mitochondria and vesicles. The sensory nature of these endings can be inferred by their extensive, but not total, elimination following neonatal capsaicin treatment (a potent neurotoxin for thin sensory fibers) and their preservation following surgical or neurotoxin sympathectomy. The thin mucosal epithelium displays capillaries and beaded axons close to the free surface of the middle ear. The unmyelinated terminals contain predominantly large, dense-core vesicles (LDCVs). Capsaicin treatment results in extensive elimination of terminals containing LDCVs in surface epithelia. A possible small trophic influence of sensory thin-fiber supply was noted on the development of the epidermal layers. The sensory modalities elicited by natural stimulation of the TM is considered in relation to the pattern of innervation.

Animals↗
PubMed1983

Optical depolarization changes on the diffraction pattern in the transition of skinned muscle fibers from relaxed to rigor state.

Light diffraction spectra from single or small bundles of skinned striated muscle fibers show large changes in polarization properties when muscles are placed into rigor. The technique of combining optical diffraction and ellipsometry measurements has previously been shown by Yeh and Pinsky to be a sensitive probe of periodic anisotropic regions of the fiber. In the present work, using this method, the observed spectrum shows marked decrease in the measured phase angle, delta, as the fiber approaches the rigor state. The degree of phase angle change is a function of sarcomere length: Maximum overlap of approximately 2.3 microns gives the most change in delta a delta delta R-R approximately 35 degrees decrease for a bundle of three fibers. At a sarcomere length of 2.9 microns this delta delta R-R value is only 10 degrees. At a nonoverlapping length of approximately 3.8 microns, delta does not vary at all upon the removal of ATP. The rigor state was confirmed by stiffness measurements made after small-amplitude (0.75%), quick length changes. Upon re-relaxation, the stiffness of the skinned fiber decreased to the value of the resting state (4 mM ATP) and the phase angle delta returned to its original value. A model based on either anisotropic subunit-2 (S-2) movements or other cross-bridge-related structural anisotropy (form birefringence) changes during the relaxed-rigor transition is suggested.

Adenosine Triphosphate↗
PubMed1983

Optical polarization properties of the diffraction spectra from single fibers of skeletal muscle.

The diffraction spectra of laser light from single fibers of skeletal muscle exhibit a large degree of optical depolarization. When the linearly polarized incident laser source is oriented at polarization angles between 0 less than theta less than pi/2 rad with respect to the fiber axis, the diffracted light is elliptically polarized. These results show that the phase angle of the ellipse rotates by as much as 20 degrees when the fiber is stretched from 2.4 to 3.8 microns. To further ascertain that the observed phenomenon is diffraction related, an experiment monitoring the spectra of scattered light in between diffraction orders showed this signal to be significantly more linearly polarized. These results suggest that the degree of elliptical polarization of the diffraction spectra is a sensitive probe of A-band dynamics, including changes of the anisotropic S-2 elements.

Animals↗
PubMed1983

Fine structure and axonal transport labeling of intraepithelial sensory nerve endings in anterior hard palate of the rat.

The fine structure of intraepithelial free nerve endings, Merkel receptors, and special (possibly chemosensory) corpuscular receptors has been examined in anterior hard palate of the rat. Samples were taken from the two anterior large rugae as well as from the more rostral incisive papilla. Most nerve endings were concentrated in regions in which the epithelium and connective tissue interdigitated extensively. The nerve endings contained relatively pale cytoplasm, a variety of vesicles, and numerous mitochondria. Distinctions could be made among different endings depending on their intraepithelial location, or on the degree of specialization of the neighboring epithelial cells. Simple (free) nerve endings entered the epithelium between epithelial papillae; upon entering, their basal lamina became associated with the epithelial basal lamina in various ways, and their Schwann cell sheath also entered the epithelium for a short length. Free nerve endings were found at various sites among the regular epithelial cells in the basal layers, the stratum granulosum, and stratum spinosum, and next to the stratum corneum border; they did not form specialized junctions with the epithelial cells. Intraepithelial nerve endings at all levels could be labeled by axonal transport from the trigeminal ganglion. Some nerve endings in anterior hard palate were associated with specialized epithelial cells, either in Merkel complexes or in apparent chemosensory corpuscles; both were labeled by axonal transport from the trigeminal ganglion. The specialized epithelial cells in the corpuscular receptors formed possible efferent and afferent synapses with the nerve endings. The nerve endings in the Merkel complexes formed junctions with the specialized Merkel epithelial cells. Both the Merkel complexes and corpuscular receptors were found in their respective characteristic epithelial papillae, which were surrounded by a dense plexus of subepithelial terminal axons and nerve endings.

Animals↗
PubMed1981

Intensity of light diffraction from striated muscle as a function of incident angle.

In a recently developed theory of light diffraction by single striated muscle fibers, we considered only the case of normal beam incidence. The present investigation represents both an experimental and theoretical extension of the previous work to arbitrary incident angle. Angle scan profiles over a 50 degrees range of incident angle (+25 degrees to -25 degrees) were obtained at different sarcomere lengths. Left and right first-order scan peak separations were found to be a function of sarcomere length (separation angle = 2 theta B), and good agreement was found between theory and experiment. Our theoretical analysis further showed that a myofibrillar population with a single common skew angle can yield an angle scan profile containing many peaks. Thus, it is not necessary to associate each peak with a different skew population. Finally, we have found that symmetry angle, theta s, also varies with sarcomere length, but not in a regular manner. Its value at a given sarcomere length is a function of a particular region of a given fiber and represents the average skew angle of all the myofibril populations illuminated. The intensity of a diffraction order line is considered to be principally the resultant of two interference phenomena. The first is a volume-grating phenomenon which results from the periodic A-I band structure of the fiber (with some contribution from Z bands and H zones). The second is Bragg reflection from skew planes, if the correct relation between incident angle and skew angle is met. This may result in intensity asymmetry between the left and right first order lines.

Animals↗
PubMed1981

Antifreeze glycoprotein. Conformational model based on vacuum ultraviolet circular dichroism data.

Circular dichroism spectra (CD) of an active fraction of antifreeze glycoprotein (AFGP) and of a lower molecular weight fraction which is less active are found to be similar in the wavelength range 170-230 nm. The contribution of the disaccharide side chain chromophores to the CD spectra of the glycoprotein is estimated from spectra of model oligosaccharides having similar structures. Comparison of the CD spectra of the peptide portion of AFGP to those of established model polypeptides suggests a 3-fold left-handed helix of the collagen type as the most likely conformation of the peptide. In the proposed model, the disaccharide moieties attached to every third residue are in identical environments. Furthermore, proline residues which are found in the less active fraction can be accommodated in this helical structure, consistent with the observed similarity of the spectra of the two fractions.

Antifreeze Proteins↗