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Biomedical subjects

C Deutsch

Publications and source records attributed to C Deutsch.

At least 91 records · Page 5Linked to original sources
PubMed1984

Evaluation of the CASPAR alcohol education curriculum.

The CASPAR education-prevention program was initiated when experimental results indicated that a 5-hr alcohol education curriculum at a Catholic high school was able to reduce frequent intoxication among teenagers. Attempts to institutionalize such a program in the public schools shows that (1) alcohol education can generate widespread community and school support; (2) workshops can successfully train teachers to adopt a decision-making approach, though close supervision is needed to ensure that this approach is adhered to in classroom teaching; (3) the CASPAR model of alcohol education produces classroom situations conducive to many children feeling free to express alcohol-related concerns; (4) trained teachers can serve as intermediaries between students with alcohol-related concerns and community resources, in particular those resources that are designed to help children from families with alcoholism; (5) the CASPAR curriculum, implemented by trained teachers, produces statistically significant knowledge and attitude gains, whereas alternate programs such as a special-events approach produce smaller knowledge gains and little attitude change; and (6) to a considerable extent, knowledge and attitude gains persist over time, although retention is greater on knowledge items and among older students. The results suggest that there may be a behavioral impact of instruction in the form of reduced alcohol misuse among teenagers, although if there is, it requires intensive and repeated exposure and can be demonstrated in these data only among younger students while they remain in junior high school. Although such results may be viewed as less supportive than the original experiment with which this work began, they do suggest that alcohol education remains an effective prevention strategy.

Adolescent↗
PubMed1983

Fluorinated alpha-methylamino acids as 19F NMR indicators of intracellular pH.

A series of nontoxic, fluorinated amino acids and their methyl esters have been used to measure intracellular pH in human peripheral blood lymphocytes by 19F NMR. Mono-, di-, and trifluoro alpha-methylalanines and their methyl esters have been characterized with respect to their spectra, the pH dependence of their fluorine resonances, and the effects of temperature and cations on the NH2pKa values. These pH indicators can be used singly or in combination to determine intracellular vs. extracellular pH profiles over a wide range (greater than 2 pH units) of extracellular pH.

Alanine↗
PubMed1983

Methylphenidate hydrochloride given with or before breakfast: I. Behavioral, cognitive, and electrophysiologic effects.

Methylphenidate HCl (Ritalin) is usually given for the treatment of hyperactivity or attention deficit disorder (ADD) at 30 minutes to one hour before meals. This schedule is based on the assumption that, when taken with meals, its absorption or metabolism is altered. However, no behavioral or pharmacologic data exist to support this recommendation. Eleven patients with attention deficit disorder were tested to evaluate this hypothesis using a double-blind crossover design (methylphenidate with or before breakfast) with a placebo control condition. Parents' ratings, performance on a paired-associate learning test, and cortical auditory-evoked potentials were measured. All of these measurements showed clear differences between the placebo condition and conditions when medication was given. However, none of the measurements showed a significant difference between the conditions when methylphenidate was given with breakfast and the condition when methylphenidate was given 30 minutes before breakfast.

Analysis of Variance↗
PubMed1982

Volume regulation of human peripheral blood lymphocytes and stimulated proliferation of volume-adapted cells.

Human peripheral blood lymphocytes exposed to hypotonic media (Ca/Mg-free, room temp.) first swell and then shrink. This shrinking response is characterized by a simple exponential with a half-time of 1.44 +/- 0.60 min (n = 11) and its extent but not the half-time for a given hypotonicity is influenced by [K+]0. Using K-selective electrodes, we observe a change in [K+]0 when cells are diluted into hypotonic media. A half-time of 1.55 +/- 0.06 min (n = 4) was obtained. A similar half-time was obtained by assay of total cell K using atomic absorption spectroscopy. At all osmolarities [K+]i was decreased from control values and was constant as [K+]0 was increased. Short-term incubation with ouabain (10(-4) M) had no effect. Decreasing osmolarities progressively inhibited phytohemagglutinin-stimulated DNA synthesis, yet cell number and viability remained unaltered. Our evidence indicates that the volume response is mediated by a change in the passive permeability of the plasma membrane to K and/or to the accompanying anions, and that the consequently volume-adapted cells are growth-inhibited.

Cell Division↗
PubMed1982

Cell calcium in human peripheral blood lymphocytes and the effect of mitogen.

The apparent cell concentration of calcium in human peripheral blood lymphocytes is 143.3 +/- 17.7 microM, as measured by two different techniques using 45Ca. The steady-state level of accumulation, and possibly the rate of uptake, are increased in the presence of succinyl-concanavalin A. Initiation of the mitogen-induced alteration of cell calcium occurs within 1-2 min and the change is complete within 5-10 min. Determinations of cell calcium in cells suspended in low Na media indicate that (1) there is no difference in cell calcium between cells incubated in 142 mM extracellular Na and cells incubated in 63 mM extracellular Na, and (2) the mitogen-induced increase in cell calcium is unaffected by a decrease in extracellular sodium concentration (to 63 mM).

Calcium↗
PubMed1982

Changes in membrane fluidity associated with lymphocyte stimulation by succinyl-concanavalin A.

Time-resolved fluorescence anisotropy studies of human peripheral blood lymphocytes labeled with 1,6-diphenyl-1,3,5-hexatriene were carried out at temperatures between 4 and 38 degrees C. For unstimulated freshly-isolated lymphocytes the calculated order parameters were found to be 0.62 at 4 degrees C and 0.44 at 37 degrees C. Mitogen-induced alterations in the order parameter were evident within minutes after addition of succinyl-concanavalin A to the cells, increasing to a value of 0.56 after 2 h at 37 degrees C. Both stimulated and unstimulated cells show a decrease in fluorescence anisotropy over the next 2-3 days of culture and after the third day the time-resolved fluorescence anisotropy decay profiles of the two populations of cells were indistinguishable. Our results indicate that there are both short- and long-term changes in the membranes of the cell upon stimulation by mitogen.

Adult↗
PubMed1982

Role of extracellular Na and K in lymphocyte activation.

The transmembrane electrical potential has been measured across human peripheral blood lymphocytes under culture conditions using equilibrium distributions of the lipophilic cation 3H-tetraphenylphosphonium (TPP). The TPP equilibrates to a steady-state level that gives calculated voltages of -80 mV for unstimulated lymphocytes. This value of the potential is constant during the first few hours of succinyl concanavalin A stimulation. When the transmembrane electrical potential is lowered by isotonic replacement of Na with K, this neither by itself stimulates proliferation nor does it inhibit mitogen-stimulated proliferation. Lymphocytes with similar membrane potentials, such as those incubated in normal-Na MEM and low-Na-mannitol MEM, exhibit drastically different proliferative responses to mitogen stimulation (Deutsch et al., 1981). These results show that isotonic replacement of K for Na prevents low Na inhibition of DNA synthesis and that at least during the first 2.5 hours of lymphocyte activation transmembrane electrical potential per se does not play a significant role in the activation process.

Extracellular Space↗
PubMed1982

Regulation of intracellular pH by human peripheral blood lymphocytes as measured by 19F NMR.

We have measured the intracellular pH of human peripheral blood lymphocytes by means of high-resolution 19F NMR spectroscopy using D,L-2-amino-3,3-difluoro-2-methylpropanoic acid (F2MeAla) as a probe. Lymphocytes readily took up the methyl ester of F2MeAla, and endogenous esterase hydrolyzed the ester to the free amino acid inside the cell. This alpha-methyl amino acid is not metabolized by the cell, and its 19F NMR spectrum exhibits large pH-dependent shifts as the alpha-amino group is protonated. The size of the 19F shifts, the high sensitivity of 19F NMR, and the favorable pKa of the alpha-amino group of F2MeAla (pKa = 7.3) allowed us to measure intracellular pH of lymphocytes at 25-30 degrees C with approximately 5-min acquisition times. Measurements at various external pH values demonstrated that human peripheral blood lymphocytes regulate their internal pH, a process requiring expenditure of metabolic energy. In the pH range between 6.8 and 7.4, lymphocytes maintain a constant internal pH of 7.17 +/- 0.06 pH unit. Outside this range, intracellular pH changes with extracellular pH. The accuracy of this 19F pH probe has been confirmed by independent measurements of intracellular pH using equilibrium distributions of 5,5-dimethyloxazolidine-2,4-dione.

Cell Membrane Permeability↗
PubMed1981

Synaptosomes from rat brain: morphology, compartmentation, and transmembrane pH and electrical gradients.

Morphological studies of synaptosomes isolated from rat brains show that approximately 68% of the synaptosomes in these preparations contain synaptic vesicles (range, 62--72.5%). Approximately 30% of the synaptosomes contain mitochondria, and only less than 20% of the total mitochondria in good preparations are free and not enclosed in synaptic structures. The mitochondrial volume percent calculated on the basis of the measured cytochrome c content is 5% for synaptosomes isolated from anesthetized animals and 11% for synaptosomes isolated from unanesthetized animals. These numbers bracket the value of 8.7% obtained from electron micrographs. The volume percent of intrasynaptic vesicles is 1.5% as calculated from electron micrographs. The pH gradient between the extracellular pH and the mean intracellular pH is --0.45, as measured by equilibrium distributions of methylamine and dimethylamine, and --0.05, as determined by equilibrium distributions of 5,5-dimethyloxazolidine-2,4-dione and trimethylacetic acid. Analysis of these data shows that there cannot be a large pH gradient (alkaline inside) across the mitochondria, nor can the synaptic vesicle compartment be very large (less than 1.85%). Equilibrium distribution of [3H]triphenylmethylphosphonium ion in synaptosomal preparations gives a calculated apparent potential of --85 mV, in agreement with our previous value. Analysis of these data using the measured volumes of mitochondrial and intrasynaptic vesicular compartments (8.7 and 1.5%, respectively) gives a maximum possible transmitochondrial membrane potential of --59 mV.

Animals↗
PubMed1979

Cellular energy metabolism, trans-plasma and trans-mitochondrial membrane potentials, and pH gradients in mouse neuroblastoma.

A method for quantitative evaluation of transmembrane electrical potential and pH gradients across a subcellular compartment in an intact cell is presented. This approach has been applied in studies of mouse neuroblastoma C-1300 clone NB41A3, in which the transmembrane electrical potential and pH gradients and the mitochondrial volume percent have been determined. Membrane potentials and pH gradients were measured by two different methods. Equilibrium distributions of [(3)H]triphenylmethyl phosphonium and [(14)C]-thiocyanate ions gave calculated apparent membrane potentials of -77.0 and -29.6 mV, respectively, at 20-25 degrees C; a value of -60.8 mV was obtained from microelectrode measurements. Equilibrium distributions of weak acids ([(14)C]trimethylacetic acid and 5,5-di[(14)C]methyl-2,4-oxazolidine-dione) and of weak bases ([(14)C]dimethylamine and [(14)C]trimethylamine) gave calculated upper and lower limits of the pH gradient (Delta pH = pH(e) - pH(i)) of -0.14 and -0.21 pH unit, respectively. The microelectrode measurements showed that the intracellular pH is within 0.1 of a pH unit or less of the extracellular pH over the extracellular pH range of 7.35-6.85. The mitochondrial volume percent calculated on the basis of the measured cytochrome c content is 5.6 +/- 1.2% and compares well with estimates of 5.4 +/- 1.1% obtained from 25 electron micrographs. Measurements of the cellular energetic parameters gave values within the range found in other cells and perfused organs. Comparison of the results of the microelectrode and equilibrium measurements permits estimates of the electrical potential and pH gradients across the mitochondrial membrane (mitochondria-to-cytoplasm gradients) to be made and suggests that the trans-mitochondrial membrane protonmotive force in the intact cell cannot be greater than -143 mV.

Animals↗
PubMedDate not supplied

K channels in T lymphocytes: a patch clamp study using monoclonal antibody adhesion.

Ionic fluxes are thought to be involved in mediating the proliferation of peripheral blood lymphocytes (PBLs) in response to mitogenic substances. Among the earliest events occurring after the addition of mitogen to cultured lymphocytes are changes in rates of cation transport. We were interested, therefore, in the possible role of ion channels in mediating the lymphocyte proliferative response. The development of patch clamp techniques by Neher and colleagues has made it possible to study membrane conductances in a variety of small cell types. We have developed a method which uses monoclonal antibodies to make cells adhere to solid surfaces for two major reasons: (1) it is much easier to patch clamp stationary cells, and (2) the method can be used to selectively adhere a particular cell type from a heterogeneous population. We have used these techniques here to identify whole-cell potassium currents, in lymphocytes recognized by OKT11 monoclonal antibody, which are increased 1.9-fold by mitogenic stimulation.

Antibodies, Monoclonal↗
PubMedDate not supplied

Cell volume regulation in lymphocytes.

This article reviews what is known about the volume regulatory responses of lymphocytes. We present a discussion of recent data and hypotheses pertaining to the underlying mechanisms in regulatory volume increase (RVI) and regulatory volume decrease (RVD). New results from our laboratory are included to demonstrate that RVD is modulated by both temperature and pH, and that RVD occurs in proliferating as well as quiescent lymphocytes. This information is considered in the context of a model that includes the dynamics of membrane potential, K+ conductance. Cl- conductance, a proposed stretch-activated conductance, gating mechanisms, and equilibrium potentials, as RVD progresses. The physiological relevance of volume homeostasis in lymphocyte function, in particular, and in cell growth and proliferation, in general, is discussed.

Humans↗