C.c Sheridan - Academia.edu (original) (raw)

Papers by C.c Sheridan

PubMed, Nov 1, 1988

A culture technique for whole blood vessel wall that preserves an intact and regenerative endothe... more A culture technique for whole blood vessel wall that preserves an intact and regenerative endothelium has been developed. The retention of an intact endothelium allows careful observation of the tissue as it responds to culture conditions, responses that include a change of replication timing and the induction of particulate endocytosis. Complete and normal regeneration of the endothelium in explants has made possible evaluation of the differences between the regeneration of endothelial cell monolayers and regeneration of intima in vivo. From these comparisons it appears that the shorter induction time of endothelial migration and proliferation and the more rapid migration in endothelial cell monolayers are due to effects of the culture medium or plastic culture surface, while the higher than normal cell density found in the intima after wound recovery in vivo probably is due to the dynamics of the blood vessel itself. The ability to control cell-cell interactions on the cultured tissue has made possible the investigation of gap junction-mediated metabolic interactions in regenerating intima. Results indicate that the disruptive effects of intimal regeneration do not depend on or produce an obvious change in junction-mediated nucleotide transfer between endothelial cells.

The Journal of Physiology, Mar 1, 1968

1. Much current thinking about voluntary movement assumes that the segmental γ loops can function... more 1. Much current thinking about voluntary movement assumes that the segmental γ loops can function as a servomechanism operated by the brain. However, the α motoneurones of the baboon's hand receive a powerful monosynaptic (CM) projection from the precentral gyrus. If servo‐driving from the same cortical area is to be possible, it must project independently to the fusimotor neurones and have sufficient power to increase the afferent signalling from the muscle spindles. The cortical thresholds for contraction of m. extensor digitorum communis and for acceleration of the discharges of its muscle spindles have therefore been compared.2. Significant results in this context require that the spindles studied be coupled in parallel with the responding extrafusal muscle fibres. Many spindles were not unloaded by the submaximal contractions evoked by cortical stimulation, although all so tested were unloaded by maximal motor nerve twitches. Reasons are given for thinking that such apparent lack of parallel coupling is an artifact of complex intramuscular anatomy and limitation of shortening by ‘isometric’ myography.3. A brief burst of corticospinal volleys at 500/sec, which is specially effective in exciting α motoneurones over the CM projection, failed to excite spindle afferents at or below the threshold for a cortical ‘twitch’.4. In a few epileptiform discharges, bursts of spindle acceleration occurred independently of the clonic contractions. A relatively direct and independent cortico‐fusimotor (CF) projection may therefore exist.5. Prolonged near‐threshold stimulation at 50‐100/sec, which allows time for temporal summation in the less direct projections (e.g. cortico‐interneuronal, cortico‐rubro‐spinal) and does not cause frequency‐potentiation at CM synapses, gives abundant evidence of independent α and fusimotor projections, whose actions hardly outlast the stimulation period.6. Although independent CF projections would permit servo‐driving in natural movements of the hand (given adequate loop gain), there has been no evidence of servo‐driving by cortical stimulation or in the spontaneous contractions of light anaesthesia.7. Independent projections would provide for controlled αγ co‐excitation in the servo‐governing of natural movements (Matthews, 1964).8. Evidence is reviewed that the CM projection itself may be part of an important control loop for voluntary movement in primates. A corollary would be a diminished importance of CF projections for segmental loops and an increased importance for maintaining the spindle input to cortical loops.

The Journal of Physiology, Feb 1, 1978

1. Adjacent acinar cells in isolated rat parotid and submaxillary glands were found to be electri... more 1. Adjacent acinar cells in isolated rat parotid and submaxillary glands were found to be electrically coupled in greater than 90 % of the pairs tested. 2. Cells injected with fluorescein or procion yellow showed transfer of the dyes to their coupled neighbours. While not all coupled cells exchanged dye, exchange occurred only between coupled cells. 3. In experiments using three micro-electrodes, coupled acinar cells from parotid gland were found to have a mean coupling coefficient of 0-69 + 0 04. This value is higher than those reported for most other vertebrate epithelial systems. 4. Membrane damage sufficient to reduce the occurrence of coupling between cells by 97 % lowered the transmembrane potential by only 13 %. This would indicate that in this system membrane potential may not be the most sensitive indicator of cell damage. 5. The significance of the presence of electrical coupling and cell-to-cell transfer of small tracer molecules is discussed in relation to salivary gland structure and possible functional consequences.

The Journal of Membrane Biology, Feb 1, 1985

Vascular endothelial cultures, derived from large vessels, retain many of the characteristics of ... more Vascular endothelial cultures, derived from large vessels, retain many of the characteristics of their in vivo counterparts. However, the observed reduction in size and complexity of intercellular gap and tight junctions in these cultured cells (Larson, D.M., and Sheridan, J.D., 1982, J. Cell Biol. 92:183) suggests that important functions, thought to be mediated by these structures, may be altered in vitro. In our continuing studies on intercellular communication in vessel wall cells, we have quantitated the extent of junctional transfer of small molecular tracers (the fluorescent dye Lucifer Yellow CH and tritiated uridine nucleotides) in confluent cultures of calf aortic (BAEC) and umbilical vein (BVEC) endothelium. Both BAEC and BVEC show extensive (and quantitatively equivalent) dye and nucleotide transfer. As an analogue of intimal endothelium, we have also tested dye transfer in freshly isolated sheets of endothelium. Transfer in BAEC and BVEC sheets was more rapid, extensive and homogeneous than in the cultured cells, implying a reduction in molecular coupling as endothelium adapts to culture conditions. In addition, we have documented heterocellular nucleotide transfer between cultured endothelium and vascular smooth muscle cells, of particular interest considering the prevalence of "myo-endothelial" junctions in vivo. These data yield further information on junctional transfer in cultured vascular endothelium and have broad implications for the functional integration of the vessel wall in the physiology and pathophysiology of the vasculature.

The Journal of physiology, 1968

The American journal of pathology, 1988

A culture technique for whole blood vessel wall that preserves an intact and regenerative endothe... more A culture technique for whole blood vessel wall that preserves an intact and regenerative endothelium has been developed. The retention of an intact endothelium allows careful observation of the tissue as it responds to culture conditions, responses that include a change of replication timing and the induction of particulate endocytosis. Complete and normal regeneration of the endothelium in explants has made possible evaluation of the differences between the regeneration of endothelial cell monolayers and regeneration of intima in vivo. From these comparisons it appears that the shorter induction time of endothelial migration and proliferation and the more rapid migration in endothelial cell monolayers are due to effects of the culture medium or plastic culture surface, while the higher than normal cell density found in the intima after wound recovery in vivo probably is due to the dynamics of the blood vessel itself. The ability to control cell-cell interactions on the cultured ti...

Journal of Modern Optics, 2004

Kogelnik's Coupled Wave Theory has been used for decades to predict the diffraction efficiency of... more Kogelnik's Coupled Wave Theory has been used for decades to predict the diffraction efficiency of volume diffraction gratings. Although this theory has been applied with success to volume diffraction gratings recorded under a great variety of experimental conditions, its predictions deviate from the actual behaviour whenever the hologram is thin or the refractive index is high. In these cases, it is necessary to use a more general Coupled Wave Theory (CW) or the Rigorous Coupled Wave Theory (RCW). Both of these theories allow for more than two orders propagating inside the hologram. The difference between them is that in the CW theory the second derivatives that appear in the coupled equations are disregarded. The RCW doesn't incorporate any approximation and thus, since it is rigorous, permits judging the accuracy of the approximations included in Kogelnik's and CW theories. In this article a comparison between the predictions of the three theories for phase transmission diffraction gratings is carried put. Over-modulated diffraction gratings are also recorded in photographic emulsions in order to study the applicability of Kogelnik's Theory in this case. Good agreement between theory and experiment is found for both Kogelnik's and Rigorous Coupled Wave Theory formulations in the particular experimental cases studied.

Science, Nov 13, 1981

Cells in isolated rat islets ofLangerhans were microinjected with Lucifer Yellow CH in a medium c... more Cells in isolated rat islets ofLangerhans were microinjected with Lucifer Yellow CH in a medium containing 16.7 millimolar glucose. Dye was rapidly transferred from the injected cell to neighboring islet cells without specificity with regard to the immunocytochemical identity of either the donor or the recipient cells. The transfer of dye between the islet cells (types A, B, and D) demonstrates homologous and heterologous cell coupling in a system where the normal proportions and relationships of the cell types are maintained.

The Journal of Physiology, 1971

The corticospinal connexions that are responsible for the firing of fusimotor impulses at short l... more The corticospinal connexions that are responsible for the firing of fusimotor impulses at short latency in response to brief, high-frequency stimulation of the baboon's motor cortex have been investigated by micro-electrode recording from antidromically identified fusimotor neurones of the forearm and hand. 2. Of nineteen fusimotor neurones investigated by intracellular recording, six showed EPSPs at monosynaptic latency. 3. In extracellular records, the latency of firing of an early fusimotor impulse was always too long to be explained by monosynaptic excitation by the corticospinal D volley, but could be explained by monosynaptic excitation from an I volley. 4. Four of the nineteen intracellularly recorded fusimotor neurones showed short-latency (? disynaptic) IPSPs in response to brief high frequency cortical bursts.

Journal of Cell Biology 97(5 Part, Jan 24, 1983

Science, 1971

York, 1968), p. 186. 10. The extent of the lesion was assessed by projecting magnified sections o... more York, 1968), p. 186. 10. The extent of the lesion was assessed by projecting magnified sections of tissue upon a page of a stereotaxic atlas that most closely corresponded to the actual section. A polar planimeter was used to convert perimeter to area, and the values obtained were analyzed with a randomization test. 11. H. F. Harlow, C. I. Thompson, A. J. Blomquist, K. A. Schiltz, Brain Res. 18, 343 (1970). 12. Supported in part by grants NB-06209 to Boston University and NB-08606 to D.S. from the National Institute of Neurological Diseases and Stroke, and by a Veterans Administration research grant to N.B. We acknowledge the help of N. Rankin with the statistical analyses, and also express our appreciation to Thornton Wheeler for his assistance in preparing the histological material. The ordering of the three authors was determined by drawing lots.

Experimental Biology and Medicine, 1971

... MARIE G. HAMMER, JUDSON D. SHERIDAN, AND RICHARD D. ESTENSEN (Introduced by PG Quie) Departni... more ... MARIE G. HAMMER, JUDSON D. SHERIDAN, AND RICHARD D. ESTENSEN (Introduced by PG Quie) Departnients of Zoology and Pathology, University of Minnesota, Minneapolis, Minnesota 55.155 ... Time after be-Cleavage giniiing of 1st - No. nff ec ted/no. ...

Experimental Cell Research, 1977

Formation of low-resistance junctions between Novikoff hepatoma cells was studied in the presence... more Formation of low-resistance junctions between Novikoff hepatoma cells was studied in the presence of inhibitors of protein synthesis or energy production. Cells were dissociated for 30 min in the presence of cycloheximide (CHX, 100 pg/ml), reaggregated by pelleting, and incubated for 60 min in the presence of CHX. This treatment (which inhibited protein synthesis by 99 % over 30 min and prevented cell growth over 12 h) produced no significant difference in % of coupled cells or in coupling coefficient between control (0.346f0.030) and treated cells (0.297f0.034). Cells were treated for 12 h in CHX before dissociation and reaggregation with some decrease in % of coupled cells, but with no substantial reduction in coupling coefficient (0.298f0.057). Multiple dissociations (and reaggregations) of the cells in the presence of CHX produced a decrease in 1 coupled cells and a slight reduction in coupling coefficients between treated (0.234+0.029) and control preparations (0.312f0.035). Cells were dissociated, treated with iodoacetate (IAA, 1 mM) for 30 min and reaggregated for 30 min. There was a small reduction in % coupled cells. Also the mean coupling coefficient was lower in treated cells (0.203f0.041) compared to controls (0.393+0.047), but this may reflect a general lowering of non-junctional membrane resistance. IAA resulted in a reduction of ATP to 5 % of the control values. Thus, neither inhibition of protein synthesis nor severe reduction of ATP levels prevent or substantially reduce junction formation by Novikoff cells.

The Journal of Cell Biology, 1981

The transformed or normal phenotype of cultured normal rat kidney cells infected with a temperatu... more The transformed or normal phenotype of cultured normal rat kidney cells infected with a temperature-sensitive mutant of avian sarcoma virus is conditional on the temperature at which the cells are grown. Using dye injection techniques, we show that junction-mediated dye transfer is also temperature-sensitive. The extent and rate of transfer between infected cells grown at the transformation-permissive temperature (35 degrees C) is significantly reduced when compared to infected cells grown at the nonpermissive temperature (40.5 degrees C) or uninfected cells grown at either temperature. Infected cells subjected to reciprocal temperature shifts express rapid and reversible alterations of dye transfer capacities, with responses evident by 15 min and completed by 60 min for temperature shifts in either direction. These results suggest that altered junctional capacities may be fundamental to the expression of the ASV-induced, transformed phenotype.

The ultrastructure of gap and tight junctions and the cell-to-cell transfer of small molecules we... more The ultrastructure of gap and tight junctions and the cell-to-cell transfer of small molecules were studied in primary cultures and freshly isolated sheets of endothelial cells from calf aortae and umbilical veins. In thin sections and in freeze-fracture replicas, the gap and tight junctions in the freshly isolated cells from both sources appeared similar to those found in the intimal endothelium. Most of the interfaces in replicas had complex arrays of multiple gap junctions either intercalated within tight junction networks or interconnected by linear particle strands. The particle density in the center of most gap junctions was noticeably reduced. In confluent monolayers, after 3-5 days in culture, gap and tight junctions were present, although reduced in complexity and apparent extent. Despite the relative simplicity of the junctions, the cell-to-cell transfer of potential changes, dye (Lucifer Yellow CH), and nucleotides was readily detectable in cultures of both endothelial ce...

Journal of Supramolecular Structure, 1979

The Journal of Cell Biology, 1971

White fat from the newt, Triturus pyrrhogaster, fat body, and brown fat from the interscapular fa... more White fat from the newt, Triturus pyrrhogaster, fat body, and brown fat from the interscapular fat pad of newborn mice have been tested for the presence of low-resistance intercellular junctions. 42 pairs of amphibian fat cells and 15 pairs of mammalian brown fat cells were found to be "electrically coupled." In most of these cases intracellular deposition of a dye, Niagara Sky Blue: 6B, was used to supplement and confirm direct observations of impalements. Coupling was often difficult to find in both preparations, but the mechanical disturbance of the tissue during the preparative procedures may have uncoupled many cells. The fact that, in both types of fat, coupling was observed between cells separated by one or more other cells suggests that coupling may be more widespread in vivo. Electron microscopy (provided by Dr. J. -P. Revel and Mrs. K. Wolken) of the brown fat revealed frequent intercellular junctions resembling "gap junctions" but possibly lacking the ...

Science, 1971

Cell junctions between Novikoff hepatoma cells (N1S1-67) growing as small clumps or chains in sus... more Cell junctions between Novikoff hepatoma cells (N1S1-67) growing as small clumps or chains in suspension culture have been studied with ultrastructural, electrophysiological, and dye-injection techniques. Cells within clumps are commonly electrically coupled and can exchange dyes with a molecular weight of 332 to 500. Gap junctions and intermediate junctions are present, whereas true tight junctions and desmosomes are absent or very rare. This system should provide a useful model for studying the properties of "communicating" junctions.

PubMed, Nov 1, 1988

A culture technique for whole blood vessel wall that preserves an intact and regenerative endothe... more A culture technique for whole blood vessel wall that preserves an intact and regenerative endothelium has been developed. The retention of an intact endothelium allows careful observation of the tissue as it responds to culture conditions, responses that include a change of replication timing and the induction of particulate endocytosis. Complete and normal regeneration of the endothelium in explants has made possible evaluation of the differences between the regeneration of endothelial cell monolayers and regeneration of intima in vivo. From these comparisons it appears that the shorter induction time of endothelial migration and proliferation and the more rapid migration in endothelial cell monolayers are due to effects of the culture medium or plastic culture surface, while the higher than normal cell density found in the intima after wound recovery in vivo probably is due to the dynamics of the blood vessel itself. The ability to control cell-cell interactions on the cultured tissue has made possible the investigation of gap junction-mediated metabolic interactions in regenerating intima. Results indicate that the disruptive effects of intimal regeneration do not depend on or produce an obvious change in junction-mediated nucleotide transfer between endothelial cells.

The Journal of Physiology, Mar 1, 1968

1. Much current thinking about voluntary movement assumes that the segmental γ loops can function... more 1. Much current thinking about voluntary movement assumes that the segmental γ loops can function as a servomechanism operated by the brain. However, the α motoneurones of the baboon's hand receive a powerful monosynaptic (CM) projection from the precentral gyrus. If servo‐driving from the same cortical area is to be possible, it must project independently to the fusimotor neurones and have sufficient power to increase the afferent signalling from the muscle spindles. The cortical thresholds for contraction of m. extensor digitorum communis and for acceleration of the discharges of its muscle spindles have therefore been compared.2. Significant results in this context require that the spindles studied be coupled in parallel with the responding extrafusal muscle fibres. Many spindles were not unloaded by the submaximal contractions evoked by cortical stimulation, although all so tested were unloaded by maximal motor nerve twitches. Reasons are given for thinking that such apparent lack of parallel coupling is an artifact of complex intramuscular anatomy and limitation of shortening by ‘isometric’ myography.3. A brief burst of corticospinal volleys at 500/sec, which is specially effective in exciting α motoneurones over the CM projection, failed to excite spindle afferents at or below the threshold for a cortical ‘twitch’.4. In a few epileptiform discharges, bursts of spindle acceleration occurred independently of the clonic contractions. A relatively direct and independent cortico‐fusimotor (CF) projection may therefore exist.5. Prolonged near‐threshold stimulation at 50‐100/sec, which allows time for temporal summation in the less direct projections (e.g. cortico‐interneuronal, cortico‐rubro‐spinal) and does not cause frequency‐potentiation at CM synapses, gives abundant evidence of independent α and fusimotor projections, whose actions hardly outlast the stimulation period.6. Although independent CF projections would permit servo‐driving in natural movements of the hand (given adequate loop gain), there has been no evidence of servo‐driving by cortical stimulation or in the spontaneous contractions of light anaesthesia.7. Independent projections would provide for controlled αγ co‐excitation in the servo‐governing of natural movements (Matthews, 1964).8. Evidence is reviewed that the CM projection itself may be part of an important control loop for voluntary movement in primates. A corollary would be a diminished importance of CF projections for segmental loops and an increased importance for maintaining the spindle input to cortical loops.

The Journal of Physiology, Feb 1, 1978

1. Adjacent acinar cells in isolated rat parotid and submaxillary glands were found to be electri... more 1. Adjacent acinar cells in isolated rat parotid and submaxillary glands were found to be electrically coupled in greater than 90 % of the pairs tested. 2. Cells injected with fluorescein or procion yellow showed transfer of the dyes to their coupled neighbours. While not all coupled cells exchanged dye, exchange occurred only between coupled cells. 3. In experiments using three micro-electrodes, coupled acinar cells from parotid gland were found to have a mean coupling coefficient of 0-69 + 0 04. This value is higher than those reported for most other vertebrate epithelial systems. 4. Membrane damage sufficient to reduce the occurrence of coupling between cells by 97 % lowered the transmembrane potential by only 13 %. This would indicate that in this system membrane potential may not be the most sensitive indicator of cell damage. 5. The significance of the presence of electrical coupling and cell-to-cell transfer of small tracer molecules is discussed in relation to salivary gland structure and possible functional consequences.

The Journal of Membrane Biology, Feb 1, 1985

Vascular endothelial cultures, derived from large vessels, retain many of the characteristics of ... more Vascular endothelial cultures, derived from large vessels, retain many of the characteristics of their in vivo counterparts. However, the observed reduction in size and complexity of intercellular gap and tight junctions in these cultured cells (Larson, D.M., and Sheridan, J.D., 1982, J. Cell Biol. 92:183) suggests that important functions, thought to be mediated by these structures, may be altered in vitro. In our continuing studies on intercellular communication in vessel wall cells, we have quantitated the extent of junctional transfer of small molecular tracers (the fluorescent dye Lucifer Yellow CH and tritiated uridine nucleotides) in confluent cultures of calf aortic (BAEC) and umbilical vein (BVEC) endothelium. Both BAEC and BVEC show extensive (and quantitatively equivalent) dye and nucleotide transfer. As an analogue of intimal endothelium, we have also tested dye transfer in freshly isolated sheets of endothelium. Transfer in BAEC and BVEC sheets was more rapid, extensive and homogeneous than in the cultured cells, implying a reduction in molecular coupling as endothelium adapts to culture conditions. In addition, we have documented heterocellular nucleotide transfer between cultured endothelium and vascular smooth muscle cells, of particular interest considering the prevalence of "myo-endothelial" junctions in vivo. These data yield further information on junctional transfer in cultured vascular endothelium and have broad implications for the functional integration of the vessel wall in the physiology and pathophysiology of the vasculature.

The Journal of physiology, 1968

The American journal of pathology, 1988

A culture technique for whole blood vessel wall that preserves an intact and regenerative endothe... more A culture technique for whole blood vessel wall that preserves an intact and regenerative endothelium has been developed. The retention of an intact endothelium allows careful observation of the tissue as it responds to culture conditions, responses that include a change of replication timing and the induction of particulate endocytosis. Complete and normal regeneration of the endothelium in explants has made possible evaluation of the differences between the regeneration of endothelial cell monolayers and regeneration of intima in vivo. From these comparisons it appears that the shorter induction time of endothelial migration and proliferation and the more rapid migration in endothelial cell monolayers are due to effects of the culture medium or plastic culture surface, while the higher than normal cell density found in the intima after wound recovery in vivo probably is due to the dynamics of the blood vessel itself. The ability to control cell-cell interactions on the cultured ti...

Journal of Modern Optics, 2004

Kogelnik's Coupled Wave Theory has been used for decades to predict the diffraction efficiency of... more Kogelnik's Coupled Wave Theory has been used for decades to predict the diffraction efficiency of volume diffraction gratings. Although this theory has been applied with success to volume diffraction gratings recorded under a great variety of experimental conditions, its predictions deviate from the actual behaviour whenever the hologram is thin or the refractive index is high. In these cases, it is necessary to use a more general Coupled Wave Theory (CW) or the Rigorous Coupled Wave Theory (RCW). Both of these theories allow for more than two orders propagating inside the hologram. The difference between them is that in the CW theory the second derivatives that appear in the coupled equations are disregarded. The RCW doesn't incorporate any approximation and thus, since it is rigorous, permits judging the accuracy of the approximations included in Kogelnik's and CW theories. In this article a comparison between the predictions of the three theories for phase transmission diffraction gratings is carried put. Over-modulated diffraction gratings are also recorded in photographic emulsions in order to study the applicability of Kogelnik's Theory in this case. Good agreement between theory and experiment is found for both Kogelnik's and Rigorous Coupled Wave Theory formulations in the particular experimental cases studied.

Science, Nov 13, 1981

Cells in isolated rat islets ofLangerhans were microinjected with Lucifer Yellow CH in a medium c... more Cells in isolated rat islets ofLangerhans were microinjected with Lucifer Yellow CH in a medium containing 16.7 millimolar glucose. Dye was rapidly transferred from the injected cell to neighboring islet cells without specificity with regard to the immunocytochemical identity of either the donor or the recipient cells. The transfer of dye between the islet cells (types A, B, and D) demonstrates homologous and heterologous cell coupling in a system where the normal proportions and relationships of the cell types are maintained.

The Journal of Physiology, 1971

The corticospinal connexions that are responsible for the firing of fusimotor impulses at short l... more The corticospinal connexions that are responsible for the firing of fusimotor impulses at short latency in response to brief, high-frequency stimulation of the baboon's motor cortex have been investigated by micro-electrode recording from antidromically identified fusimotor neurones of the forearm and hand. 2. Of nineteen fusimotor neurones investigated by intracellular recording, six showed EPSPs at monosynaptic latency. 3. In extracellular records, the latency of firing of an early fusimotor impulse was always too long to be explained by monosynaptic excitation by the corticospinal D volley, but could be explained by monosynaptic excitation from an I volley. 4. Four of the nineteen intracellularly recorded fusimotor neurones showed short-latency (? disynaptic) IPSPs in response to brief high frequency cortical bursts.

Journal of Cell Biology 97(5 Part, Jan 24, 1983

Science, 1971

York, 1968), p. 186. 10. The extent of the lesion was assessed by projecting magnified sections o... more York, 1968), p. 186. 10. The extent of the lesion was assessed by projecting magnified sections of tissue upon a page of a stereotaxic atlas that most closely corresponded to the actual section. A polar planimeter was used to convert perimeter to area, and the values obtained were analyzed with a randomization test. 11. H. F. Harlow, C. I. Thompson, A. J. Blomquist, K. A. Schiltz, Brain Res. 18, 343 (1970). 12. Supported in part by grants NB-06209 to Boston University and NB-08606 to D.S. from the National Institute of Neurological Diseases and Stroke, and by a Veterans Administration research grant to N.B. We acknowledge the help of N. Rankin with the statistical analyses, and also express our appreciation to Thornton Wheeler for his assistance in preparing the histological material. The ordering of the three authors was determined by drawing lots.

Experimental Biology and Medicine, 1971

... MARIE G. HAMMER, JUDSON D. SHERIDAN, AND RICHARD D. ESTENSEN (Introduced by PG Quie) Departni... more ... MARIE G. HAMMER, JUDSON D. SHERIDAN, AND RICHARD D. ESTENSEN (Introduced by PG Quie) Departnients of Zoology and Pathology, University of Minnesota, Minneapolis, Minnesota 55.155 ... Time after be-Cleavage giniiing of 1st - No. nff ec ted/no. ...

Experimental Cell Research, 1977

Formation of low-resistance junctions between Novikoff hepatoma cells was studied in the presence... more Formation of low-resistance junctions between Novikoff hepatoma cells was studied in the presence of inhibitors of protein synthesis or energy production. Cells were dissociated for 30 min in the presence of cycloheximide (CHX, 100 pg/ml), reaggregated by pelleting, and incubated for 60 min in the presence of CHX. This treatment (which inhibited protein synthesis by 99 % over 30 min and prevented cell growth over 12 h) produced no significant difference in % of coupled cells or in coupling coefficient between control (0.346f0.030) and treated cells (0.297f0.034). Cells were treated for 12 h in CHX before dissociation and reaggregation with some decrease in % of coupled cells, but with no substantial reduction in coupling coefficient (0.298f0.057). Multiple dissociations (and reaggregations) of the cells in the presence of CHX produced a decrease in 1 coupled cells and a slight reduction in coupling coefficients between treated (0.234+0.029) and control preparations (0.312f0.035). Cells were dissociated, treated with iodoacetate (IAA, 1 mM) for 30 min and reaggregated for 30 min. There was a small reduction in % coupled cells. Also the mean coupling coefficient was lower in treated cells (0.203f0.041) compared to controls (0.393+0.047), but this may reflect a general lowering of non-junctional membrane resistance. IAA resulted in a reduction of ATP to 5 % of the control values. Thus, neither inhibition of protein synthesis nor severe reduction of ATP levels prevent or substantially reduce junction formation by Novikoff cells.

The Journal of Cell Biology, 1981

The transformed or normal phenotype of cultured normal rat kidney cells infected with a temperatu... more The transformed or normal phenotype of cultured normal rat kidney cells infected with a temperature-sensitive mutant of avian sarcoma virus is conditional on the temperature at which the cells are grown. Using dye injection techniques, we show that junction-mediated dye transfer is also temperature-sensitive. The extent and rate of transfer between infected cells grown at the transformation-permissive temperature (35 degrees C) is significantly reduced when compared to infected cells grown at the nonpermissive temperature (40.5 degrees C) or uninfected cells grown at either temperature. Infected cells subjected to reciprocal temperature shifts express rapid and reversible alterations of dye transfer capacities, with responses evident by 15 min and completed by 60 min for temperature shifts in either direction. These results suggest that altered junctional capacities may be fundamental to the expression of the ASV-induced, transformed phenotype.

The ultrastructure of gap and tight junctions and the cell-to-cell transfer of small molecules we... more The ultrastructure of gap and tight junctions and the cell-to-cell transfer of small molecules were studied in primary cultures and freshly isolated sheets of endothelial cells from calf aortae and umbilical veins. In thin sections and in freeze-fracture replicas, the gap and tight junctions in the freshly isolated cells from both sources appeared similar to those found in the intimal endothelium. Most of the interfaces in replicas had complex arrays of multiple gap junctions either intercalated within tight junction networks or interconnected by linear particle strands. The particle density in the center of most gap junctions was noticeably reduced. In confluent monolayers, after 3-5 days in culture, gap and tight junctions were present, although reduced in complexity and apparent extent. Despite the relative simplicity of the junctions, the cell-to-cell transfer of potential changes, dye (Lucifer Yellow CH), and nucleotides was readily detectable in cultures of both endothelial ce...

Journal of Supramolecular Structure, 1979

The Journal of Cell Biology, 1971

White fat from the newt, Triturus pyrrhogaster, fat body, and brown fat from the interscapular fa... more White fat from the newt, Triturus pyrrhogaster, fat body, and brown fat from the interscapular fat pad of newborn mice have been tested for the presence of low-resistance intercellular junctions. 42 pairs of amphibian fat cells and 15 pairs of mammalian brown fat cells were found to be "electrically coupled." In most of these cases intracellular deposition of a dye, Niagara Sky Blue: 6B, was used to supplement and confirm direct observations of impalements. Coupling was often difficult to find in both preparations, but the mechanical disturbance of the tissue during the preparative procedures may have uncoupled many cells. The fact that, in both types of fat, coupling was observed between cells separated by one or more other cells suggests that coupling may be more widespread in vivo. Electron microscopy (provided by Dr. J. -P. Revel and Mrs. K. Wolken) of the brown fat revealed frequent intercellular junctions resembling "gap junctions" but possibly lacking the ...

Science, 1971

Cell junctions between Novikoff hepatoma cells (N1S1-67) growing as small clumps or chains in sus... more Cell junctions between Novikoff hepatoma cells (N1S1-67) growing as small clumps or chains in suspension culture have been studied with ultrastructural, electrophysiological, and dye-injection techniques. Cells within clumps are commonly electrically coupled and can exchange dyes with a molecular weight of 332 to 500. Gap junctions and intermediate junctions are present, whereas true tight junctions and desmosomes are absent or very rare. This system should provide a useful model for studying the properties of "communicating" junctions.