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Query: UMLS:C0019829 (Hodgkin's disease)
 30,247 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Muscle fibres of crustaceans represent an useful model for studying the mode of action of substances influencing calcium channels as the membrane generates the active responses on a pure calcium principle and the excitation-contraction link is dependent on external calcium. We followed the effect of Pb2+ ions (1-300 mumol/l) on contractile responses in single muscle fibres of the crayfish evoked by massive or intracellular electrical stimulation, by potassium depolarization and caffeine application, as well as on action potential in single intact muscle fibres and on calcium currents in voltage clamp conditions (vaseline gap) in internally perfused muscle fibre segments. All types of contractile responses, single twitches, tetanus, potassium and caffeine contractures were blocked. The strontium action potential was blocked very effectively by Pb2+ ions. The total calcium currents which can be split by means of Hodgkin-Huxley equations into two components (fast and slow respectively) differing in the rate of activation and inactivation were suppressed after addition of Pb(NO3)2 (50-300 mumol/l). The effect of Pb2+ was concentration and time dependent. At lower concentrations (100 mumol/l) the blocking effect was more pronounced on the fast inactivating Ca current component. The Pb2+ ions prolonged the time constant of inactivation tau h of the slow channel, while leaving that of the fast channel intact.
Gen Physiol Biophys 1993 Apr
PMID:The effect of Pb2+ ions on calcium currents and contractility in single muscle fibres of the crayfish. 840 21

Myxococcus xanthus, a bacterium that forms fruiting bodies, moves by gliding motility utilizing dual motility systems that differ both genetically and morphologically [system A, having at least 21 genetic loci and moving mainly single cells, and system S, having at least 10 genetic loci and moving groups (rafts) of cells] [Hodgkin, J. & Kaiser, D. (1979) Mol. Gen. Genet. 172, 177-191]. In this study, we found that A- and S-gliding-motility systems have different selective advantages on surfaces containing different concentrations of agar. We observed that colonies of A+S- cells (A-motile cells) swarmed better than A-S+ cells (S-motile cells) on relatively firm and dry surfaces (e.g., 1.5% agar). In contrast, colonies of A-S+ cells swarmed much better than A+S- cells on soft and wet surfaces (e.g., 0.3% agar). Individual A-motile cells moved at a rate of 2-4 microns/min on 1.5% agar but they barely moved on 0.3% agar (< 0.5 microns/min); in contrast S-motile cells moved 3-5 times faster on 0.3% agar than on 1.5% agar. Wild-type cells with both A- and S-motility systems were able to move well over a wide range of surfaces. These results suggest that dual motility systems enable the myxobacteria to adapt to a variety of physiological and ecological environments and show similarities in function to the dual motility systems of flagellated bacteria such as Vibrio spp.
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PMID:The two motility systems of Myxococcus xanthus show different selective advantages on various surfaces. 847 84

Enzymatically isolated myocytes from ferret right ventricles (12-16 wk, male) were studied using the whole cell patch clamp technique. The macroscopic properties of a transient outward K+ current I(to) were quantified. I(to) is selective for K+, with a PNa/PK of 0.082. Activation of I(to) is a voltage-dependent process, with both activation and inactivation being independent of Na+ or Ca2+ influx. Steady-state inactivation is well described by a single Boltzmann relationship (V1/2 = -13.5 mV; k = 5.6 mV). Substantial inactivation can occur during a subthreshold depolarization without any measurable macroscopic current. Both development of and recovery from inactivation are well described by single exponential processes. Ensemble averages of single I(to) channel currents recorded in cell-attached patches reproduce macroscopic I(to) and indicate that inactivation is complete at depolarized potentials. The overall inactivation/recovery time constant curve has a bell-shaped potential dependence that peaks between -10 and -20 mV, with time constants (22 degrees C) ranging from 23 ms (-90 mV) to 304 ms (-10 mV). Steady-state activation displays a sigmoidal dependence on membrane potential, with a net aggregate half-activation potential of +22.5 mV. Activation kinetics (0 to +70 mV, 22 degrees C) are rapid, with I(to) peaking in approximately 5-15 ms at +50 mV. Experiments conducted at reduced temperatures (12 degrees C) demonstrate that activation occurs with a time delay. A nonlinear least-squares analysis indicates that three closed kinetic states are necessary and sufficient to model activation. Derived time constants of activation (22 degrees C) ranged from 10 ms (+10 mV) to 2 ms (+70 mV). Within the framework of Hodgkin-Huxley formalism, Ito gating can be described using an a3i formulation.
J Gen Physiol 1993 Apr
PMID:The calcium-independent transient outward potassium current in isolated ferret right ventricular myocytes. I. Basic characterization and kinetic analysis. 850 27

The electrophysiological properties of HK2 (Kv1.5), a K+ channel cloned from human ventricle, were investigated after stable expression in a mouse Ltk- cell line. Cell lines that expressed HK2 mRNA displayed a current with delayed rectifier properties at 23 degrees C, while sham transfected cell lines showed neither specific HK2 mRNA hybridization nor voltage-activated currents under whole cell conditions. The expression of the HK2 current has been stable for over two years. The dependence of the reversal potential of this current on the external K+ concentration (55 mV/decade) confirmed K+ selectivity, and the tail envelope test was satisfied, indicating expression of a single population of K+ channels. The activation time course was fast and sigmoidal (time constants declined from 10 ms to < 2 ms between 0 and +60 mV). The midpoint and slope factor of the activation curve were Eh = -14 +/- 5 mV and k = 5.9 +/- 0.9 (n = 31), respectively. Slow partial inactivation was observed especially at large depolarizations (20 +/- 2% after 250 ms at +60 mV, n = 32), and was incomplete in 5 s (69 +/- 3%, n = 14). This slow inactivation appeared to be a genuine gating process and not due to K+ accumulation, because it was present regardless of the size of the current and was observed even with 140 mM external K+ concentration. Slow inactivation had a biexponential time course with largely voltage-independent time constants of approximately 240 and 2,700 ms between -10 and +60 mV. The voltage dependence of slow inactivation overlapped with that of activation: Eh = -25 +/- 4 mV and k = 3.7 +/- 0.7 (n = 14). The fully activated current-voltage relationship displayed outward rectification in 4 mM external K+ concentration, but was more linear at higher external K+ concentrations, changes that could be explained in part on the basis of constant field (Goldman-Hodgkin-Katz) rectification. Activation and inactivation kinetics displayed a marked temperature dependence, resulting in faster activation and enhanced inactivation at higher temperature. The current was sensitive to low concentrations of 4-aminopyridine, but relatively insensitive to external TEA and to high concentrations of dendrotoxin. The expressed current did not resemble either the rapid or the slow components of delayed rectification described in guinea pig myocytes. However, this channel has many similarities to the rapidly activating delayed rectifying currents described in adult rat atrial and neonatal canine epicardial myocytes.(ABSTRACT TRUNCATED AT 400 WORDS)
J Gen Physiol 1993 Apr
PMID:A rapidly activating and slowly inactivating potassium channel cloned from human heart. Functional analysis after stable mammalian cell culture expression. 850 26

The proliferations of the connective tissue, which are summed up under the term fibromatoses, assume a special position with regard to their biologic behavior. While superficial fibromatoses are more likely to grow slowly, musculoaponeurotic fibromatoses (Desmoid tumor)--like malignant tumors--show a locally bound aggressive, rapid growth behavior. A metastazation, however, can never be proved. The research on etiology of fibromatoses has yielded only little knowledge. Besides genetic and hormonal factors, physical reasons are under discussion, too. The present study aims to add another description of a case report to the small number of case presentations on radiotherapy-associated fibromatosis. In 1977, a now 67-old-patient was irradiated because of a Morbus Hodgkin lymphoma in the left side of his neck. Prior to the radiation, the patient had undergone several surgeries. 17 years after the radiation, the patient developed an aggressive fibromatosis (prelaryngeal, right) in the formerly irradiated region. As the localization of the fibromatosis does not allow us to establish a connection to his numerous operations preceding the fibromatosis, a radiation-associated Desmoid tumor must be assumed. Immunohistologically, no estrogen receptors were detectable.
Gen Diagn Pathol 1995 Oct
PMID:Extra-abdominal aggressive fibromatosis after treatment of a Morbus Hodgkin. A case report. 854 97

Kinetic models to describe the time course of the Ca(2+)-independent outward potassium current (Ito) in cardiac ventricular cells were constructed. The Ito traces were recorded from isolated myocytes of rats and mice using the whole-cell configuration of the patch-clamp technique. An iterative method was developed to eliminate the capacitive transient overlapping the early part of the Ito. The isolated Ito curves were then fitted by Hodgkin-Huxley type functions and different inactivation gating mechanisms were identified in various groups of the animals. In some Wistar rats a single inactivation route was found. Another group of Wistar rats and diabetic BB/Mol rats showed two independent inactivation pathways both of which resulted in a completely closed channel. In lean specimen of C-57 mice and in streptozotocin-treated Wistar rats the two inactivation gates gave closed channels only when both parallel inactivating transitions have been completed. In this case a possible interaction between the gating particles has been revealed.
Gen Physiol Biophys 1995 Aug
PMID:Three different gating models for inactivation of the Ito in ventricular myocytes of rats and mice. 872 Jun 91

The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.12 < f < 300 Hz, the power density spectrum of whole-cell Cl- currents could be fitted by three Lorentzians. Independent of membrane potential, >50% of the total variance of whole-cell current fluctuations was accounted for by the low frequency Lorentzian (fc = 0.40 +/- 0.03 Hz, n = 6). Single-Cl- channels showed complex gating kinetics with long lasting (seconds) openings interrupted by similar long closures. In the open state, channels exhibited fast burst-like closures. Since the patches normally contained more than a single channel, it was not possible to measure open and closed dwell-time distributions for comparing single-Cl- channel activity with the kinetic features of whole-cell currents. However, the power density spectrum of Cl- currents of cell-attached and excised outside-out patches contained both high and low frequency Lorentzian components, with the corner frequency of the slow component (fc = 0.40 +/- 0.02 Hz, n = 4) similar to that of whole-cell current fluctuations. Chloride channels exhibited multiple conductance states with similar Goldman-Hodgkin-Katz-type rectification. Single-channel permeabilities covered the range from approximately 0.6.10(-14) cm5/s to approximately 6.10(-14) cm3/s, corresponding to a limiting conductance (gamma 150/150) of approximately 3.5 pS and approximately 35 pS, respectively. All states reversed near the same membrane potential, and they exhibited similar halide ion selectivity, P1 > PCl approximately PBr. Accordingly, Cl- current amplitudes larger than current flow through the smallest channel unit resolved seem to result from simultaneous open/shut events of two or more channel units.
J Gen Physiol 1996 Jun
PMID:Endogenous chloride channels of insect sf9 cells. Evidence for coordinated activity of small elementary channel units. 878 71

Primary non-Hodgkin lymphoma of bone is an unusual extranodal presentation, and considerable difficulty exists in diagnosing some extranodal osseous lymphomas that develop in the head and neck region. Frequently, malignancies of the jawbones appear clinically as inflammatory diseases. Recognition of these cases usually occurs after the inflammatory-like symptoms have failed to respond to conventional therapy. This case report presents an extranodal non-Hodgkin lymphoma of the maxilla, which clinically imposed as odontogenic infection in a 45-year-old woman. The definite diagnosis was made by histologic means and confirmed by polymerase chain reaction (PCR). The latter is a molecular biologic method, which in unclear cases may be helpful in early differentiation of inflammatory from malignant processes.
Gen Diagn Pathol 1996 Jun
PMID:Diagnosis of non-Hodgkin lymphoma of the maxilla with support of polymerase chain reaction. 879 87

A method is described for the determination of reversal potentials (EREV) from variance of single-channel currents vs. membrane potential in ramp pulse mode. The variance-voltage relationship is represented by a parabola with a minimum of the best fit curve corresponding to the value of EREV. The reversal potential of the maxi-Cl channels changes according to the activity of Cl ions at the internal side of the excised (inside-out) patch membrane as expressed by the Goldman-Hodgkin-Katz equation with PA/PCl = 0.15, indicating the anion nature of the channel. The relative permeabilities (PA/PCl found for halide anions, were 1.15 for iodide and 1.18 for bromide. The relative permeabilities measured (PA/PCl) for other anions were 1.13 for nitrate, 0.59 for bicarbonate, 0.60 for methanesulfonate, 0.40 for SO42-, 0.44 for propionate, and 0.10 for glutamate. No significant differences in PA/PCl of the investigated anions were observed between proliferating myoballs and quiescent myoblasts. This may mean that the newly formed channels possess full-grown selective filters. A close correlation (r = 0.89) was found between the calculated Stokes diameters of the anions under investigation and their relative permeabilities (PA/PCl). The intercept of the best fit line with the abscissa is 7.2 A (7.2 x 10(-10)m), which may correspond to the diameter of the selectivity filter of the maxi-chloride channel in L6 myoblasts. A similar value of the channel size was obtained from the relationship between the minimum cross-sectional areas of the anions and their relative permeabilities, PA/PCl. The best fit line intercepts the abscissa at 27.5 A2, indicating a pore size approximately 6 A. The minimum areas were obtained by computer from molecular models of the anions.
Gen Physiol Biophys 1995 Apr
PMID:Selectivity of maxi chloride channels in the L6 rat muscle cell line. 884 86

The isolated epithelium of toad skin was disintegrated into single cells by treatment with collagenase and trypsine. Chloride channels of cell-attached and excised inside-out apical membrane-patches of mitochondria-rich cells were studied by the patch-clamp technique. The major population of Cl- channels constituted small 7-pS linear channels in symmetrical solutions (125 mM Cl-). In cell-attached and inside-out patches the single channel i/V-relationship could be described by electrodiffusion of Cl- with a Goldmann-Hodgkin-Katz permeability of, PCl = 1.2 x 10(-14) - 2.6 x 10(-14) cm3. s-1. The channel exhibited voltage-independent activity and could be activated by cAMP. This channel is a likely candidate for mediating the well known cAMP-induced transepithelial Cl- conductance of the amphibian skin epithelium. Another population of Cl- channels exhibited large, highly variable conductances (upper limit conductances, 150-550 pS) and could be activated by membrane depolarization. A group of intermediate-sized Cl(-)-channels included: (a) channels (mean conductance, 30 pS) with linear or slightly outwardly rectifying i/V-relationships and activity occurring in distinct "bursts," (b) channels (conductance-range, 10-27 pS) with marked depolarization-induced activity, and (c) channels with unresolvable kinetics. The variance of current fluctuations of such "noisy" patches exhibited a minimum close to the equilibrium-potential for Cl-. With channels occurring in only 38% of sealed patches and an even lower frequency of voltage-activated channels, the chloride conductance of the apical membrane of mitochondria-rich cells did not match quantitatively that previously estimated from macroscopic Ussing-chamber experiments. From a qualitative point of view, however, we have succeeded in demonstrating the existence of Cl-channels in the apical membrane with features comparable to macroscopic predictions, i.e., activation of channel gating by cAMP and, in a few patches, also by membrane depolarization.
J Gen Physiol 1996 Nov
PMID:Heterogeneity of chloride channels in the apical membrane of isolated mitochondria-rich cells from toad skin. 892 67


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