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  1. Article: The membrane locus of Ca-stimulated K transport in energy depleted human red blood cells.

    Blum, R M / Hoffman, J F

    The Journal of membrane biology

    2013  Volume 6, Issue 4, Page(s) 315–328

    Abstract: Energy depleted human red cells subsequently exposed to iodoacetate (IAA) develop, upon the addition of Ca, a marked increase in K permeability, while Na permeability is unaltered. The kinetic characteristics of this augmented K permeability indicate ... ...

    Abstract Energy depleted human red cells subsequently exposed to iodoacetate (IAA) develop, upon the addition of Ca, a marked increase in K permeability, while Na permeability is unaltered. The kinetic characteristics of this augmented K permeability indicate that the transport process is membrane mediated. Thus, the inward and outward rate constants for K increase as the concentration of external K is increased reaching maximum values between 2 to 5MM; further increases in external K results in a partial reduction of the rate constants. In addition, the Ca-stimulated K transport system displays counterflow of(42)K during its influx when a large gradient of(39)K exists (inside high, outside low). Furthermore, the Ca-induced K transport is inhibited by ouabain. The sensitivity of the Ca-induced system to ouabain parallels the action of ouabain on the Na-K pump. At least part of the increased K transport occurs through a preexisting pathway since ouabain bound to cells before exposure to Ca and IAA results in an inhibition of K outflux. Since ouabain does not alter the affinity of the cells for Ca, it is concluded that at least a portion of the increased K transport results from Ca acting to increase the turnover rate of the same system which serves as the Na-K pump in normal red cells.
    Language English
    Publishing date 2013-10-29
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3082-x
    ISSN 1432-1424 ; 0022-2631
    ISSN (online) 1432-1424
    ISSN 0022-2631
    DOI 10.1007/BF02116577
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  2. Article: Cation transport and structure of the red-cell plasma membrane.

    HOFFMAN, J F

    Circulation

    2003  Volume 26, Page(s) 1202–1213

    MeSH term(s) Cations ; Cell Biology ; Erythrocyte Membrane ; Erythrocytes ; Permeability ; Plasma
    Chemical Substances Cations
    Language English
    Publishing date 2003-06-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 80099-5
    ISSN 1524-4539 ; 0009-7322 ; 0069-4193 ; 0065-8499
    ISSN (online) 1524-4539
    ISSN 0009-7322 ; 0069-4193 ; 0065-8499
    DOI 10.1161/01.cir.26.5.1201
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: On the reproducibility in the observed ultrastructure of the normal mammalian red cell plasma membrane.

    HOFFMAN, J F

    Journal of cellular and comparative physiology

    2003  Volume 47, Issue 2, Page(s) 261–287

    MeSH term(s) Animals ; Cell Membrane ; Electrons ; Erythrocytes ; Humans ; Mammals ; Microscopy ; Microscopy, Electron ; Reproducibility of Results
    Language English
    Publishing date 2003-11-19
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3117-3
    ISSN 0095-9898
    ISSN 0095-9898
    DOI 10.1002/jcp.1030470206
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  4. Article: Interactions of the fluorescent anion 1-anilino-8-naphthalene sulfonate with membrane charges in human red cell ghosts.

    George Fortes, P A / Hoffman, J F

    The Journal of membrane biology

    2013  Volume 5, Issue 2, Page(s) 154–168

    Abstract: The interaction of the fluorescent anion 1-anilino-8-naphthalene sulfonate (ANS) with erythrocyte membranes was studied as a function of the charges in the membrane. The membrane charges were altered by including in the incubation medium the organic ions ...

    Abstract The interaction of the fluorescent anion 1-anilino-8-naphthalene sulfonate (ANS) with erythrocyte membranes was studied as a function of the charges in the membrane. The membrane charges were altered by including in the incubation medium the organic ions tetraphenylboron (TPB(-)), tetraphenylarsonium (TPA(+)) and tetraphenylphosphonium (TPP(+)) which differ in charge but have similar structure and high affinity for the membrane. TPB(-) decreases whereas TPA(+) and TPP(+) increase ANS fluorescence arising from the membrane. The fluorescence changes are accompanied by variations in the affinity and capacity of the membrane for ANS. The fluorescence arising under conditions where all the ANS present is within the membrane (by extrapolation to infinite membrane concentration) does not vary with these ions. Salicylate and SCN(-) which inhbit anion permeability also decrease ANS fluorescence with no apparent change in quantum yield. These results indicate that ANS exists as an anion in the membrane, associated with the regions involved in ion permeability, and that the concentration of ANS in the membrane is a function of the concentration of all the ions present in the medium and their relative affinities for the membrane. Thus, variations in ANS fluorescence reflect redistributions of the ANS ions following changes in electrostatic interactions with the membrane fixed charges.
    Language English
    Publishing date 2013-10-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3082-x
    ISSN 1432-1424 ; 0022-2631
    ISSN (online) 1432-1424
    ISSN 0022-2631
    DOI 10.1007/BF02107721
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  5. Article: Questions for red blood cell physiologists to ponder in this millenium.

    Hoffman, J F

    Blood cells, molecules & diseases

    2001  Volume 27, Issue 1, Page(s) 57–61

    MeSH term(s) Animals ; Cell Physiological Phenomena ; Erythrocytes/cytology ; Erythrocytes/metabolism ; Erythrocytes/physiology ; Humans ; Research
    Language English
    Publishing date 2001-01
    Publishing country United States
    Document type Editorial
    ZDB-ID 1237083-6
    ISSN 1096-0961 ; 1079-9796
    ISSN (online) 1096-0961
    ISSN 1079-9796
    DOI 10.1006/bcmd.2000.0351
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  6. Article: A brief history of the Red Cell Club.

    Hoffman, J F

    Blood cells, molecules & diseases

    2001  Volume 27, Issue 1, Page(s) 54–56

    MeSH term(s) Animals ; Congresses as Topic/history ; Erythrocytes ; History, 20th Century ; History, 21st Century ; Humans ; Societies, Scientific/history
    Language English
    Publishing date 2001-01
    Publishing country United States
    Document type Historical Article ; Journal Article
    ZDB-ID 1237083-6
    ISSN 1096-0961 ; 1079-9796
    ISSN (online) 1096-0961
    ISSN 1079-9796
    DOI 10.1006/bcmd.2000.0350
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  7. Article: Management of scalp defects.

    Hoffman, J F

    Otolaryngologic clinics of North America

    2001  Volume 34, Issue 3, Page(s) 571–582

    Abstract: This article presents a systematic approach to the reconstruction of scalp defects, which includes a review of the anatomy of the scalp as it pertains to reconstruction, and a discussion of the various reconstructive options for scalp defects, such as ... ...

    Abstract This article presents a systematic approach to the reconstruction of scalp defects, which includes a review of the anatomy of the scalp as it pertains to reconstruction, and a discussion of the various reconstructive options for scalp defects, such as grafts and flaps. Further, scalp flap selection, design, and execution are outlined. Finally, adjunctive techniques of tissue expansion and hair transplants are included to enhance the final aesthetic result.
    MeSH term(s) Humans ; Scalp/abnormalities ; Scalp/blood supply ; Scalp/surgery ; Surgical Flaps ; Tissue Expansion
    Language English
    Publishing date 2001-06-29
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 417489-6
    ISSN 1557-8259 ; 0030-6665
    ISSN (online) 1557-8259
    ISSN 0030-6665
    DOI 10.1016/s0030-6665(05)70006-2
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  8. Article: Physiological characteristics of human red blood cell ghosts.

    HOFFMAN, J F

    The Journal of general physiology

    2000  Volume 42, Issue 1, Page(s) 9–28

    Abstract: The properties of ghosts prepared by hypotonic hemolysis at various ratios of cells (C) to hemolyzing solution (H) have been studied. At all ratios, hemoglobin (Hb) was found to be distributed equally between the ghost and supernatant compartments. ... ...

    Abstract The properties of ghosts prepared by hypotonic hemolysis at various ratios of cells (C) to hemolyzing solution (H) have been studied. At all ratios, hemoglobin (Hb) was found to be distributed equally between the ghost and supernatant compartments. Techniques employing Fe(59)-labelled Hb showed that during hemolysis all of the Hb is exchangeable and that following hemolysis the ghost is impermeable to Hb. Ghosts containing defined fractions of their original Hb were prepared by appropriately altering the ratio C/H. When washed and suspended in 0.17 M NaCl-PO(4)-buffered media, the ghosts returned to their initial volume, recovered normal shape, and behaved as osmometers. The rate of rehemolysis of these reconstituted ghosts was observed to be proportional to the concentration of Hb in the ghosts. The rate of rehemolysis was accelerated by the addition of n-butyl alcohol (BA). For a given concentration of BA, temperature, and Hb content the rate of rehemolysis was minimal around the isoelectric point of Hb. Rehemolysis by BA was inhibited by the addition of sucrose to the medium. K influx and outflux were measured and found to be increased by the addition of BA and not influenced by the presence of sucrose. These results on the rehemolytic characteristics of ghosts are consistent with and support the colloid-osmotic theory of hemolysis.
    MeSH term(s) Erythrocyte Membrane ; Erythrocytes ; Hemoglobins ; Hemolysis ; Humans ; Sodium Chloride
    Chemical Substances Hemoglobins ; Sodium Chloride (451W47IQ8X)
    Language English
    Publishing date 2000-12-20
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3118-5
    ISSN 1540-7748 ; 0022-1295
    ISSN (online) 1540-7748
    ISSN 0022-1295
    DOI 10.1085/jgp.42.1.9
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  9. Article: The active transport of sodium by ghosts of human red blood cells.

    HOFFMAN, J F

    The Journal of general physiology

    2000  Volume 45, Page(s) 837–859

    Abstract: The outflux of Na(24) from prelabeled ghosts was measured under various conditions. Prelabeling was accomplished by hypotonic hemolysis of intact human cells in the presence of tracer Na(24). The resultant ghosts when subsequently washed were found to ... ...

    Abstract The outflux of Na(24) from prelabeled ghosts was measured under various conditions. Prelabeling was accomplished by hypotonic hemolysis of intact human cells in the presence of tracer Na(24). The resultant ghosts when subsequently washed were found to retain 10 to 20 per cent of the initial Na(24). Separate experiments indicated that this trapped amount resides in only a portion of ghosts comprising the total population. The characteristics of the outflux of this residual Na(24) indicated that the ghost system closely resembles intact red cells. The outflux of Na from ghosts could be divided into three components: active and passive transport and exchange diffusion. The active transport system, necessarily driven by metabolism, required the presence of K in the extracellular phase and was blocked by strophanthidin. The concentration dependence of the Na pump flux on the external K and internal Na appeared the same in ghosts as in intact cells. Certain other features of this ghost system are also discussed.
    MeSH term(s) Biological Transport ; Biological Transport, Active ; Diffusion ; Erythrocyte Membrane ; Erythrocytes/physiology ; Humans ; Ions ; Sodium/blood
    Chemical Substances Ions ; Sodium (9NEZ333N27)
    Language English
    Publishing date 2000-12-20
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3118-5
    ISSN 1540-7748 ; 0022-1295
    ISSN (online) 1540-7748
    ISSN 0022-1295
    DOI 10.1085/jgp.45.5.837
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  10. Article: ATP compartmentation in human erythrocytes.

    Hoffman, J F

    Current opinion in hematology

    1997  Volume 4, Issue 2, Page(s) 112–115

    Abstract: This review covers not only the current status of the field but also the evidence on which the concept of ATP compartmentation is based. It is hoped that such a survey may help to stimulate work in this area and to broaden the appreciation of its reality ...

    Abstract This review covers not only the current status of the field but also the evidence on which the concept of ATP compartmentation is based. It is hoped that such a survey may help to stimulate work in this area and to broaden the appreciation of its reality and functions. Some may be surprised to learn that mature human erythrocytes, known to be devoid of intracellular organelles, can sequester ATP, but they may not have taken into account the possible roles of the complex cytoskeleton that is tethered to the cells' plasma membrane. The functional significance of the ATP pools springs from the likelihood that they serve as both an energy reserve, capable of sustaining ion pumping during periods of transient stress, as well as a putative transduction mechanism by which the cell's cytoskeleton may sense cellular energy stores.
    MeSH term(s) Adenosine Triphosphate/analysis ; Adenosine Triphosphate/metabolism ; Cell Compartmentation ; Erythrocytes/metabolism ; Erythrocytes/ultrastructure ; Humans
    Chemical Substances Adenosine Triphosphate (8L70Q75FXE)
    Language English
    Publishing date 1997-03
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, P.H.S. ; Review
    ZDB-ID 1153887-9
    ISSN 1531-7048 ; 1065-6251
    ISSN (online) 1531-7048
    ISSN 1065-6251
    DOI 10.1097/00062752-199704020-00006
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