The role of low intracellular or extracellular pH in sensitization to hyperthermic radiosensitization.

Previous work showed that intracellular pH (pHi) and not extracellular pH (pHe) was the determinant in the low pH sensitization of hyperthermic killing. The present studies show that the same is true for heat-induced radiosensitization and loss of cellular DNA polymerase activities. Chinese hamster ovary cells after they had adapted to low pH (6.

Interaction of morphine with intrathecally administered calcium and calcium antagonists: evidence for supraspinal endogenous opioid mediation of intrathecal calcium-induced antinociception in mice.

The interaction between morphine [i.p. and intrathecal (i.

Thermotolerance induced by heat, sodium arsenite, or puromycin: its inhibition and differences between 43 degrees C and 45 degrees C.

When CHO cells were treated either for 10 min at 45-45.5 degrees C or for 1 hr with 100 microM sodium arsenite (ARS) or for 2 hr with 20 micrograms/ml puromycin (PUR-20), they became thermotolerant to a heat treatment at 45-45.5 degrees C administered 4-14 hr later, with thermotolerance ratios at 10(-3) isosurvival of 4-6, 2-3.

Differential effects of subcutaneous and intrathecal morphine administration on blood glucose in mice: comparison with intracerebroventricular administration.

The s.c. administration of morphine (2.

The role of low intracellular or extracellular pH in sensitization to hyperthermia.

Cells are more sensitive to heat when they are heated in an acidic environment, and this study confirms (K. G. Hofer and N.

Recovery from effects of heat on DNA synthesis in Chinese hamster ovary cells.

The hyperthermic inhibition of cellular DNA synthesis, i.e., reduction in replicon initiation and delay in DNA chain elongation, was previously postulated to be involved in the induction of chromosomal aberrations believed to be largely responsible for killing S-phase cells.

Antagonism of antinociception in mice by glucose and fructose: comparison of subcutaneous and intrathecal morphine.

Determination of the ED50s of glucose and fructose, administered i.p., for antagonizing the antinociceptive action of morphine (4 mg/kg s.

Time-temperature analyses of cell killing of synchronous G1 and S phase Chinese hamster cells in vitro.

Time-temperature analyses of durations of heating required to achieve isosurvival were used to compare hyperthermic cell killing of synchronous Chinese hamster ovary (CHO) cells heated in G1 or S at temperatures of 42 to 45.5 degrees C. G1 populations were obtained by incubation of mitotic cells for 90 min at 37 degrees C.

An investigation of the antinociceptive activity of calcitonin gene-related peptide alone and in combination with morphine: correlation to 45Ca++ uptake by synaptosomes.

A 5- or 30-min incubation of synaptosomes with calcitonin gene-related peptide (CGRP) (10(-6), 10(-7), 10(-8) M) produced increases in 45Ca++ uptake upon depolarization of the synaptosomes, whereas a naloxone-reversible decrease in 45Ca++ uptake was seen after a 1-hr incubation with CGRP. Morphine-induced (10(-6) M) decreases in 45Ca++ uptake were reversed by simultaneous 5-min incubation of synaptosomes with CGRP (10(-6) M) and were enhanced by a 1-hr preincubation of the synaptosomes with CGRP (10(-6) M). CGRP produced naloxone-reversible antinociception in both the p-phenylquinone and hot-plate tests at 1 hr after i.

Effect of cycloheximide on heat-induced cell killing, radiosensitization, and loss of cellular DNA polymerase activities in Chinese hamster ovary cells.

A whole-cell assay technique for DNA polymerase alpha and beta was used to measure the activities of both enzymes in Chinese hamster ovary cells after hyperthermic treatment at 43 degrees C in the presence or absence of 10 micrograms/ml cycloheximide (CHM). In the same experiments, the effect of CHM on heat killing and heat radiosensitization was also investigated. CHM treatment before and during heating protected the cells for all three end points, i.

Effect of cycloheximide or puromycin on induction of thermotolerance by heat in Chinese hamster ovary cells: dose fractionation at 45.5 degrees C1.

While studying the quantitative relationship between hyperthermia-induced heat shock proteins (HSPs) and thermotolerance (TT), we observed that heat induced a family of HSPs, particularly an HSP 70 family, that might be involved in the development of TT. When cells were heated for 10 min at 45.5 degrees C, they became thermotolerant to a second heat exposure at 45.

Increased cerebrospinal fluid beta-endorphin immunoreactivity in infants with apnea and in siblings of victims of sudden infant death syndrome.

To gain further insight into the possible role of endogenous opioid peptides in the respiratory difficulties associated with the apnea of infancy and other disorders possibly related to apnea, the levels of beta-endorphin immunoreactivity were measured in the cerebrospinal fluid (CSF) of five groups of infants: (1) infants with proved apnea, (2) infants with histories of an apparent life-threatening event (ALTE), (3) siblings of victims of the sudden infant death syndrome (SIDS), (4) infants with suspected but unproved apnea, and (5) infants undergoing investigation for other acute illnesses. Twenty-two infants considered at risk for an ALTE (groups 1 to 3) had significantly higher CSF beta-endorphin equivalents (88 +/- 7 pg/mL) than did the 22 control patients in groups 4 and 5 (31 +/- 3 pg/mL). Plasma beta-endorphin immunoreactivity, which was also measured in some of the infants, did not correlate with levels in CSF and, in fact, was significantly lower in the groups at risk for an ALTE (50 +/- 9 pg/mL; n = 14) than in the control subjects (80 +/- 6 pg/mL; n = 11).

Effects of glucose and diabetes on binding of naloxone and dihydromorphine to opiate receptors in mouse brain.

The effects of glucose and diabetes on the high-affinity lofentanil-displaceable opiate-receptor binding in mouse brain membranes were studied to determine if the attenuation of opiate actions by hyperglycemia previously observed in our laboratory was due to a modification of receptor affinity or number. With membranes from normal ICR mice, glucose (100-400 mg/dl) caused small but significant concentration-dependent decreases in receptor affinities for [3H]naloxone and [3H]dihydromorphine, both in the absence and presence of 20 mM NaCl, without changing the maximum number of binding sites. Fructose and the nonmetabolizable sugar 3-O-methylglucose had intermediate effects on naloxone affinity in the presence of NaCl that were not significantly different from control or from the effect of glucose.

Protection of Chinese hamster ovary cells from heat killing by treatment with cycloheximide or puromycin: involvement of HSPs?

Cycloheximide (CHM) or puromycin (PUR) added for 2 h before heating at 43 degrees C followed by either PUR or CHM during heat greatly protected cells from heat killing. This protection increased with inhibition of protein synthesis. Since treatment with a drug both before and during heating was required for heat protection, and since one drug could be exchanged for the other after the 2-h pretreatment without affecting the heat protection, a common mode of action involving inhibition of protein synthesis is suggested for the two drugs.

Cardiovascular effects of delta 9- and delta 9(11)-tetrahydrocannabinol and their interaction with epinephrine.

The administration of delta-9-tetrahydrocannabinol (delta 9-THC, 0.078-5.0 mg/kg, i.

Effect of cycloheximide or puromycin on induction of thermotolerance by sodium arsenite in Chinese hamster ovary cells: involvement of heat shock proteins.

After sodium arsenite (100 microM) treatment, the synthesis of three major heat shock protein families (HSPs; Mr = 110,000, 87,000, and 70,000), as studied with one-dimensional gels, was enhanced twofold relative to that of unheated cells. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater. In parallel, thermotolerance was observed as a 100,000-fold increase in survival from 10(-6) to 10(-1) after 4 hr at 43 degrees C, and as a thermotolerance ratio (TTR) of 2-3 at 10(-3) isosurvival for heating at 45.

Induction of heat shock proteins in Chinese hamster ovary cells and development of thermotolerance by intermediate concentrations of puromycin.

During 4 hr after puromycin (PUR: 20 micrograms/ml) treatment, the synthesis of three major heat shock protein families (HSPs: Mr = 110,000, 87,000, and 70,000) was enhanced 1.5-fold relative to that of untreated cells, as studied by one-dimensional gel electrophoresis. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater.

Hydrogen peroxide or heat shock induces resistance to hydrogen peroxide in Chinese hamster fibroblasts.

Survival after H2O2 exposure or heat shock of asynchronous Chinese hamster ovary cells (HA-1) was assayed following pretreatment with mildly toxic doses of either H2O2 or hyperthermia. H2O2 cytotoxicity at 37 degrees C, expressed as a function of mM H2O2 was found to be dependent on cell density at the time of treatment. The density dependence reflected the ability of cells to reduce the effectiveness of H2O2 as a cytotoxic agent.

A method for freezing synchronous mitotic and G1 cells.

A modification of the protocol developed by Kawamoto, J C & Barrett, J N, Brain res (1986), in press for freezing primary neuron cultures in a solution containing low sodium and high lactate and potassium concentrations was used to freeze synchronous mitotic and G1 CHO cells. After thawing, the cells behaved as if they had never been frozen with respect to cell growth, cell division, plating efficiency, and hyperthermic sensitivity.

Effect of hyperthermia on intracellular pH in Chinese hamster ovary cells.

Chinese hamster ovary cells were heated at 45.5 or 43.0 degrees C at acidic pH (6.

Modulation of cellular heat sensitivity by specific amino acids.

When either plateau-phase or exponentially growing Chinese hamster ovary (CHO) cells are incubated in amino acid-free medium, the cells become sensitized to killing by heat. For cells deprived of amino acids for 12 h survival decreases from 1 X 10(-2) for controls to 1 X 10(-6) for the deprived cells, following heating at 45 degrees C for 38 min. The survival of these sensitized cells is rapidly increased by the addition of a single amino acid just prior to heating.

Increased plasma beta-endorphin immunoreactivity in scuba divers after submersion.

Increased plasma beta-endorphin immunoreactivity in scuba divers after submersion. Med. Sci.

Effects of cannabinoids on levels of acetylcholine and choline and on turnover rate of acetylcholine in various regions of the mouse brain.

The psychoactive cannabinoids, delta 9-tetrahydrocannabinol (delta 9-THC), delta 8-tetrahydrocannabinol (delta 8-THC), 11-hydroxy-delta 9-tetrahydrocannabinol (11-OH-delta 9-THC) and 9-nor-9 beta-hydroxyhexahydrocannabinol (beta-HHC), as well as the nonpsychoactive cannabinoids, cannabinol (CBN), cannabidiol (CBD), abnormal CBD, delta 8-THC methyl ether (1-OCH3-delta 8-THC) and 9-nor-9 alpha-hydroxyhexahydrocannabinol (alpha-HHC), were used to assess the role of cholinergic mechanisms in the different behavioral actions of these cannabinoids. Their effects on mouse brain choline and acetylcholine (ACh) levels and on ACh turnover were determined in cortex, hippocampus, striatum, midbrain and medulla-pons. delta 9-THC (30 mg/kg) caused a significant elevation of ACh in all five brain areas.

Opiate addiction and plasma beta-endorphin-like immunoreactivity: methadone maintained, recently detoxified and early naltrexone treated ex-addicts.

Plasma beta-endorphin-like radioimmunoreactivity (BEND) was measured in opiate addicts and controls with an antisera which cross reacted with lipotropin but not with other endogenous opiate peptides. 43 stable male methadone maintained patients had mean BEND of 18 +/- 11 pg/ml. No relationship was found between BEND, and time of day, dose or time since last methadone.