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Biomedical subjects

C Deutsch

Publications and source records attributed to C Deutsch.

At least 73 records · Page 4Linked to original sources
PubMed1989

Modulation of K+ currents in human lymphocytes by pH.

1. Using whole-cell patch-clamp techniques, we found that the voltage-dependent K+ conductance in human peripheral blood T lymphocytes is enhanced threefold at alkaline intracellular pH (pHi) compared to acid pHi. This pH dependence can be described by a model having two strongly co-operative proton binding sites with pka 7.15. A similar pHi sensitivity exists for K+ conductance in mitogen-activated cells. 2. The reversal potential, threshold voltage for activation of the K+ conductance, and voltage dependence of steady-state inactivation are not affected by pHi. Activation and inactivation kinetics are also unchanged. 3. Single-channel measurements made in whole-cell patch-clamp mode indicate that the effect of intracellular pH on the amplitudes of single-channel events parallels, but does not wholly account for, the effect of pHi on the macroscopic currents. 4. Lowering extracellular pH (pHo) shifts the threshold for activation of the K+ current to a more depolarized voltage, consistent with a surface charge screening effect. Apparent changes in peak current and activation kinetics at acid pHo can be accounted for by this voltage shift. An additional slowing of inactivation kinetics at low pHo does occur. 5. The relevance of the pH sensitivity of the voltage-gated K+ conductance to lymphocyte mitogenesis and volume regulation is discussed.

Electrophysiology↗
PubMed1989

[Comparative studies of the calibration of new electronic automatic tonometers].

Over the last years the number of newly developed automatic microprocessor controlled tonometers has been increasing. These devices follow totally different measurement principles. Therefore the physical methods for calibration of these tonometers differ widely. Described is the possibility of calibration of new microprocessor-controlled tonometers. First the Tonopen, which follows the Mackay-Marg principle was tested. Its accuracy in measuring the intraocular pressure and its independency of position was examined. Moreover, the non-contact tonometers were tested. Especially the airstream of non-contact tonometers (CT 10, Pulsair) was measured with a Constant Temperature Anemometer (CTA). The topspeed of the airstream was 335 km/h for the CT 10 and 249 km/h for the Pulsair tonometer. The profile of the airstream was paraboloid. The base measured about 5 mm in diameter. For detection of the effect of the airstream to the cornea, a camera was connected over a special interface with the CT 10 and triggered with a flashlight generator. The airstream produced at the moment of pressure measurement an exact applanation of the cornea with a diameter of about 4 mm. The results demonstrate the possibility of physical calibration, but this does not substitute biometrical measurements.

Calibration↗
PubMed1988

Decisions near the end of life.

Designing behavior change programs and evaluating their effects on patient care has been a persistent challenge in research on continuing medical education. The challenge becomes even more complex when we aim to change behaviors that are interactive and highly influenced by the formal and informal institutional context. The authors describe an interdisciplinary continuing education program in bioethics that is designed to effect just such behaviors. The program aims to help hospital and long-term care facilities improve their ability to resolve the ethical dilemmas inherent in terminal care decisions. Targeted to interdisciplinary groups of physicians, nurses, social workers, pastoral counselors, and administrators, Decisions Near the End of Life will provide strategies and tools for examining institutional policies and team practices as well as more traditional information, education, and skill building. The authors describe the program's rationale and design, and raise questions about the potential for developing interdisciplinary, action-oriented CME on other topics.

Decision Making↗
PubMed1988

Forskolin effects on the voltage-gated K+ conductance of human T cells.

Forskolin, a direct activator of adenylate cyclase, modifies the voltage-dependent K+ conductance of quiescent human peripheral blood T lymphocytes. In the presence of greater than 20 microM forskolin, the average voltage-gated current in whole-cell patch clamp is significantly decreased. The voltage dependence and kinetics of activation are not changed from untreated control cells. However, inactivation becomes biphasic. Much of the current inactivates very quickly (complete in 10 ms), and the remaining outward current inactivates more slowly with a time constant closer to that of control cells. To determine whether this effect is mediated by a rise in intracellular cAMP, cells were preincubated and subsequently voltage-clamped in the presence of other agents that raise the cAMP levels in T cells (isoproterenol plus a phosphodiesterase inhibitor, or dibutyryl cAMP) with no effect on the K+ conductance. Similarly, cells put in whole-cell patch clamp with cAMP, GTP, ATP, and theophylline added to the electrode filling solution showed no change in K+ current. Because other procedures that raise cAMP did not duplicate the effect of forskolin, we investigated the effect of 1,9-dideoxyforskolin, an analogue of forskolin that does not stimulate adenylate cyclase in human lymphocytes. This drug induced changes in the whole-cell K+ conductance identical to those observed with forskolin. Both forskolin and dideoxyforskolin inhibit mitogen-induced proliferation of lymphocytes. Because inhibition of proliferation occurs in the presence of known K+ channel blockers, these results suggest that forskolin has an effect on T cell mitogenesis that is mediated by inhibition of K+ conductance and is independent of cAMP.

Adenylyl Cyclases↗
PubMed1988

19F-nuclear magnetic resonance: measurements of [O2] and pH in biological systems.

19F-nuclear magnetic resonance (NMR) has been used to determine both intracellular pH and oxygen concentrations in cell suspensions. Oxygen concentrations in Paracoccus denitrificans and insulinoma cells, RINm5F, in the NMR probe can be monitored directly by 1/T1 measurements of perfluorotripropylamine (FTPA)/lecithin emulsion added to the suspensions. With FTPA oxygen monitoring, we investigated the relative aeration capabilities of two types of NMR chambers. Both normal and transformed eucaryotic cells can be maintained in either chamber for at least 1-2 h at cytocrits of up to 20-25%, with 30% oxygen saturation and cell viabilities of 90-95%. Similar concentrations of procaryotes were maintained aerobic with high FTPA concentrations in the more efficient of the two NMR chambers. A new precursor molecule for the 19F-NMR pH indicator difluoromethylalanine, the para-chlorophenyl ester, has been tested and used in RINm5F cells and P. denitrificans, neither of which hydrolyzes methyl esters.

Animals↗
PubMed1988

Comparison of ion channels in multidrug-resistant and -sensitive human leukemic cells.

Tumor cell lines selected to grow in the presence of one "natural product" antineoplastic drug often develop cross-resistance to others. This multidrug resistance (MDR) is believed to be a major problem in cancer therapy. Organic Ca2+-channel blockers, such as verapamil, can reverse this resistance and render MDR cells in culture nearly as sensitive to the antineoplastic drugs as the drug-sensitive cells from which they were derived. It has therefore been suggested that Ca2+ channels may play a role in MDR. To determine directly whether there are electrophysiological correlates of MDR, we used whole-cell and single-channel patch-clamp techniques to survey the ion channels in a drug-sensitive human T-cell leukemia line, CCRF-CEM, and a MDR variant, CEM/VLB100. We found no evidence for a voltage-gated Ca2+ channel. However, we did identify three other current/channel types: a voltage-gated tetrodotoxin-sensitive inward current carried by Na+, a voltage-gated labile outward current carried by K+, and a nonselective cation channel reversing at 0 mV. Drug-sensitive and -resistant cells were the same with respect to the level of expression of these channels.

Antineoplastic Agents↗
PubMed1988

Volume response of quiescent and interleukin 2-stimulated T-lymphocytes to hypotonicity.

Regulatory volume decreased (RVD) in lymphocytes in response to hyptonically induced swelling is dependent on the membrane permeabilities of K+, Cl-, and H2O. We used electronic cell sizing, cell water determination, and the whole cell patch-clamp method to study these membrane permeabilities in the cloned mouse T-lymphocyte, L2. Quiescent L2 cells express low levels of a voltage-gated K+ channel and show no RVD at 25 degrees C. In contrast, L2 cells stimulated to proliferate with the growth factor interleukin 2 have increased K+ conductance and show RVD in response to hypotonicity. RVD in stimulated cells is blocked by quinine and verapamil at levels that also completely block the voltage-gated K+ conductance. Swollen, unstimulated L2 cells can be induced to shrink by addition of the monovalent cation ionophore gramicidin in the presence of impermeant extracellular organic cations; gramicidin also enhances the rate of RVD in stimulated cells. Additionally, the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) blocks this gramicidin-facilitated RVD. These results suggest that a minimum requisite Cl- permeability is present even in the unstimulated L2 cells, that a necessary and limiting K+ permeability determines the rate of RVD, and that this K+ permeability increases after growth-factor stimulation as predicted from the direct measurement of voltage-gated K+ conductance. The hydraulic permeability is approximately 70% greater in proliferating L2 cells than in quiescent cells. At 37 degrees C, some RVD occurs in unstimulated L2 cells, and stimulated cells show faster and more complete shrinkage. These results are discussed with respect to the underlying membrane permeabilities and their relation to stimulated cell proliferation.

Animals↗
PubMed1986

Cloned T-cell proliferation and synthesis of specific proteins are inhibited by quinine.

Recombinant human interleukin 2 (rIL-2) drives the proliferation of the cloned murine T-helper line L2. The initial G1 activation occurs during the first 20 hr after stimulation, with DNA synthesis (S phase) beginning approximately 20 hr after rIL-2 stimulation. Three patterns of protein synthesis were observed during G1 activation. Type I proteins (e.g., p72 and p66) were synthesized at near maximal rates as early as 4 hr after stimulation, with little change in rates of synthesis through the G1 to S phase transition. Type II proteins (e.g., p52 and p36) were detectable early after stimulation, but their rates of synthesis continued to increase throughout G1 activation, becoming maximal 24-28 hr after stimulation. Type III proteins (e.g., p93, p89, and p63) were synthesized maximally 4 or 8 hr after rIL-2 stimulation, then their rates of synthesis declined markedly to prestimulation levels. Type II proteins, p52 and p36, were shown to be correlated with cell proliferation, since their rates of synthesis were maximal while L2 cells were proliferating and declined as the cells returned to a quiescent state. The potassium channel blocker quinine inhibited cell growth and the synthesis of p52 and p36 when added 0 or 2 hr after rIL-2 stimulation but not when added 6 hr after rIL-2 stimulation. Thus, a quinine-sensitive event occurring in L2 cells between 2 and 6 hr after rIL-2 stimulation is necessary for synthesis of type II proteins, DNA synthesis, and cell proliferation.

Animals↗
PubMed1986

Increased voltage-gated potassium conductance during interleukin 2-stimulated proliferation of a mouse helper T lymphocyte clone.

Recent work has demonstrated the presence of voltage-gated potassium channels in human peripheral blood T lymphocytes (Matteson, R., and C. Deutsch, 1984, Nature (Lond.), 307:468-471; DeCoursey T. E., T. G. Chandy, S. Gupta, and M. D. Cahalan, 1984, Nature (Lond.), 307:465-468) and a murine cytolytic T-cell clone (Fukushima, Y., S. Hagiwara, and M. Henkart, 1984, J. Physiol., 351:645-656). Using the whole cell patch clamp, we have found a potassium conductance with similar properties in a murine noncytolytic T lymphocyte clone, L2. Under voltage clamp, a step from a holding potential of -70 mV to +50 mV produces an average outward current of 100-150 pA in "quiescent" L2 cells at the end of their weekly maintenance cycle. When these cells are stimulated with human recombinant interleukin 2 (rIL2, 100 U/ml), they grow in size and initiate DNA synthesis at approximately 24 h. Potassium conductance is increased as early as 8 h after stimulation with rIL2 and rises to a level 3-4 times that of excipient controls by 24 h. The level remains elevated through 72 h, but as the cells begin to leave the cell cycle at 72-96 h, the conductance decreases quickly to a value only slightly higher than the initial one. Quinine, a blocker of this conductance, markedly reduces the rate at which L2 cells traverse the cell cycle, while also reducing the rate of stimulated protein synthesis. The regulation of potassium conductance in L2 cells during rIL2-stimulated proliferation suggests that potassium channel function may play a role in support of the proliferative response.

Animals↗
PubMed1986

Voltage-gated potassium conductance in human T lymphocytes stimulated with phorbol ester.

The whole-cell patch-clamp method was used to study the voltage-gated K+ conductance of human peripheral blood T lymphocytes. After entry into whole-cell recording mode, there are time-dependent changes in some properties of the conductance. Over the first 10-30 min, the threshold for activation shifts about 10 mV more negative, and the rates of activation and inactivation increase. Inactivation is less strongly voltage dependent than activation or deactivation. Lymphocytes were stimulated to proliferate in culture with the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). No changes in K+ conductance were observed in the first few hours of TPA stimulation. At 24 h after mitogen addition, TPA-treated cells were found to have 1.7-fold greater average voltage-gated K+ conductance than unstimulated control cells. At 48 h, TPA-stimulated cells had the same average K+ conductance as at 24 h, even though the cells were now much increased in size, as measured by cell capacitance. DNA synthesis by cultures stimulated with TPA, phytohaemagglutinin or succinyl concanavalin A was depressed by the addition of 0.1 mM-quinine at any point in the culture period. In the first 20 h after mitogen addition, DNA synthesis was more effectively inhibited by quinine than if the drug were added later. Cell proliferation was equally sensitive to quinine regardless of mitogen.

Action Potentials↗
PubMed1985

Adolescent sexuality in a therapeutic community: staff countertransference issues.

Issues connected with sexuality such as heterosexual relationships, homosexuality, sexual identity, and seductiveness, create conflict and countertransference dilemmas for staff who work with psychiatric patients in a therapeutic community. When the therapeutic community is composed of adolescents, these issues are exacerbated since sexual identity and sexual development are major concerns. The staff reacts strongly to the issue of self-determination and violation/infringement on a basic human need. These philosophical differences have their roots in countertransference feelings. Staff sometimes find it difficult to confront adolescents on emotionally charged issues that have a sexual coloring. A system is proposed for articulating and working through these feelings. A unique solution is posited for solving this conflictual attitude (based on object relations theory), whereby the residential treatment center serves as the analog of the home in order to allow adolescents to develop a sense of self before they can move on to the halfway house where heterosexual behavior is allowed (as part of the therapeutic process). This facilitates the meeting of the "self" with the "other." This procedure is explored in light of Sullivan's concept of intimacy.

Adolescent↗
PubMed1984

Anthropometric proportions in the upper lip-lower lip-chin area of the lower face in young white adults.

The relationships between measurements of the lower lip, chin, upper lip, and lower half and lower third of the face were studied. Fifteen new indices were formed with the help of eleven vertical linear, one horizontal linear, and two surface-arc measurements in the area. Neoclassic canons related to the lower face were not confirmed. On the average, the lower lip was 83% to 85% as large as the upper lip. The upper lip occupied one third of the lower face, while the lower lip occupied more than one third of the lower third of the face and the chin occupied the remainder. Skin covered 73.5% of the upper lip in males and 68% in females; it covered 63% of the lower lip in males and 61.1% in females. The remainder was covered by vermilion, more on the lower than on the upper lip and more protruding in females than in males. Proportion standards are a valuable contribution to the surface anatomy of the lower face of young white adults.

Adolescent↗
PubMed1984

pH homeostasis in human lymphocytes: modulation by ions and mitogen.

Quiescent human peripheral blood lymphocytes have been shown to maintain a relatively constant intracellular pH of 7.0-7.2 over an extracellular pH range of 6.9-7.4. Two methods of measuring intracellular pH were used in these studies, 19F nuclear magnetic resonance and [14C]5,5-dimethyloxazolidine-2,4-dione (DMO) equilibrium distributions. When ATP levels were decreased in these cells, actively maintained pH regulation was abolished and cells exhibited a constant pH gradient of 0.2 pH unit (acid inside relative to outside). Possible mechanisms for pH regulation are discussed. The effects of the Na+ and K+ composition of the medium on pH regulation showed no correlation with their effects on mitogen-induced proliferative response, which we have previously determined (Deutsch, C., and M. Price, 1982, J. Cell. Physiol., 111:73-79). In low-Na+ mannitol medium, pH regulation was similar to that observed for lymphocytes in normal medium, whereas mitogen-induced proliferation was severely inhibited in low-Na+ mannitol. In contrast, high-K+, low Na+ medium caused loss of pH homeostasis, whereas it restored the proliferative response. Loss of pH homeostasis was also observed on prolonged exposure of lymphocytes to mitogen (greater than 6 h in culture). However, mitogen stimulation led to little or no change in intracellular pH in the first few hours of cell culture. Therefore, a shift in intracellular pH is not a necessary or general event in mitogen-stimulated proliferation of lymphocytes.

Adenosine Triphosphate↗
PubMed1984

Intracellular pH of perfused single frog skin: combined 19F- and 31P-NMR analysis.

Intracellular pH (pHc) has been determined in frog skin by applying two different methods of pH measurement, 19F and 31P nuclear magnetic resonance (NMR) analysis, to the same tissues. Results from both NMR approaches confirm an observation by Lin, Shporer, and Civan [Am. J. Physiol. 248 (Cell Physiol. 17): 1985] that acidification of the extracellular medium reverses the sign of the pH gradient present under baseline conditions. The fluorinated probe, alpha-(difluoromethyl)-alanine methyl ester, was introduced into the epithelial cells by preincubating skins for 4.7-10.4 h at room temperature in Ringer solutions containing 1 mM ester. The free amino acid was subsequently released by intracellular esterase activity, thus providing a high enough probe concentration for NMR analysis to be practicable. From measurements of short-circuit current and transepithelial resistance under base-line and experimental conditions and the appearance of phosphocreatine (PCr) in the 31P spectrum of preloaded tissues, the fluorinated probe appears to be nontoxic to frog skin. Measurement of the chemical shift of methylphosphonate relative to PCr permitted calculation of extracellular pH. Estimation of the intracellular pH was performed both by measurement of the chemical shift of inorganic phosphate (Pi) relative to PCr and by measurement of the central peak spacing of the 19F spectrum. From four direct comparisons of the two techniques in two experiments, the difference in the estimated pH was only 0.03 +/- 0.07 pH units, supporting the concept that 31P-NMR analysis is a valid method of measuring pH in this tissue.

Animals↗