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Biomedical subjects

J P McCormick

Publications and source records attributed to J P McCormick.

12 recordsLinked to original sources
PubMed1993

Cantharidin production in a blister beetle.

Cantharidin, a potent defensive chemical, is present in all ten life stages of the blister beetle Epicauta funebris. The first five larval stages accumulate cantharidin as they feed and grow in size. When disturbed, they exude cantharidin in a milky oral fluid, not in hemolymph which adult beetles reflexively discharge from leg joints. Two subsequent larval stages and the pupa do not feed, grow, regurgitate, or change in their defensive reserves (110 micrograms cantharidin/insect, regardless of sex). Adult beetles kept in isolation for 60-90 d exhibit a pronounced sexual dimorphism in cantharidin production: the male biosynthesizes about 17 mg of the toxin, representing 10% of his live weight, whereas the female actually loses most of her defensive reserves. But in the wild a female beetle repeatedly acquires cantharidin as copulatory gifts from her mates.

Age Factors↗
PubMed1988

Comparison of chlordimeform and carbaryl using a functional observational battery.

The effects of the formamidine pesticide chlordimeform (CDM), and the carbamate carbaryl (CAR) were compared using a functional observational battery (FOB). The FOB, a series of observations and measurements that can be rapidly administered to toxicant-treated rats, includes home-cage and open-field observations, neuromuscular and sensorimotor tests, and physiological measures. Evaluations were made according to U.S. Environmental Protection Agency testing guidelines so as to determine dose-, time-, and sex-related toxicant effects. Long-Evans hooded rats of both sexes were tested initially and then dosed ip with either vehicle, CDM (1, 25, 56 mg/kg) or CAR (3, 10, 30 mg/kg), and tested at various times after dosing (for CDM 1, 5, 24 hr; for CAR 0.5, 3, 24, 48 hr). Both compounds affected general activity (home-cage and open-field), equilibrium, CNS excitability, and sensory responsiveness. Whereas similar decreases were obtained on rearing, gait, and arousal, there were important qualitative differences in the effects of CAR and CDM on reactions to handling and the reflex tests in that CDM increased excitability and enhanced responses to several stimuli but CAR either had no effect or decreased these measures. Only CDM produced an increase in muscle tone as measured by grip strength, and only CAR produced cholinergic autonomic signs of intoxication. Body weight and temperature were decreased by both compounds. Thus, the profiles of effect produced by these two pesticides could be clearly differentiated using the FOB.

Amidines↗
PubMed1988

Lacinilene C methyl ether (LCME) constricts tracheal smooth muscle.

Lacinilene C methyl ether (LCME) is a constituent of the cotton plant and has been implicated as a causative agent of byssinosis. The effect of synthetic LCME on the behavior of isolated strips of canine tracheal smooth muscle (TSM) was examined in tissue bath experiments. LCME (0.64-6.6 x 10(-4) M) caused slowly developing but strong and sustained contractions of TSM strips. Blockade of acetycholine, 5-hydroxytryptamine (5-HT), and histamine H1 receptors with atropine, methysergide, and pyrilamine, respectively, had no effect on constrictions induced by LCME. In contrast, the calcium channel antagonist, verapamil, significantly reduced the response to LCME. Moreover, addition of the beta receptor agonist, isoproterenol, at the peak of LCME-induced contractions relaxed tissues in a concentration-dependent manner. We conclude that LCME elicits contraction of TSM by enhancing the movement of calcium through potential-dependent channels of smooth muscle cell membranes. This mechanism of action does not require activation of specific membrane receptors for acetylcholine, 5-HT, and histamine.

Animals↗
PubMed1987

The impact of crime victimization and fear of crime on attitudes toward death penalty defendants.

A 1983 telephone survey of 610 respondents in two Maryland counties found that the general disposition of the respondents toward the criminal justice system was a better predictor of abstract attitudes toward the death penalty than either the respondents' fear of becoming crime victims or whether they had been victims of crime. Yet respondents' fear of crime victimization was a better predictor of their willingness to impose the death penalty or to accept mitigating circumstances during the penalty phase of a capital case than their abstract attitudes toward the criminal justice system. Respondents who were "somewhat" afraid of crime victimization were less likely to support the death penalty than were respondents who were "very" afraid or "not" afraid of victimization. These finding indicate that previous research on the death penalty may have been flawed because the wording of the questions asked was too abstract and unidimensional.

Attitude to Death↗
PubMed1985

Toxicokinetics of toluene in the rat.

Toxicokinetic experiments with toluene that rely on data pooled from several animals have typically provided estimates of rate constants based on single exponential functions; in the present study a within-subject design was used to describe the time course of toluene in the blood to see if additional exponential terms could be resolved. Each rat was exposed for 2 h to either 1 000, 1 780, or 3 000 ppm of toluene. Blood samples were drawn at different times from indwelling jugular cannulae, and blood toluene concentrations were determined by vapor phase equilibrium chromatography. There was substantial variability between the peak blood values of the animals at each exposure concentration. Nonlinear regression was used to determine regression parameters for data drawn from individual animals. A bi-exponential function was found to minimize significantly the residual sum of squares observed during elimination. However, only a single exponential function could be resolved reliably during uptake. The mean half-time during uptake was approximately 34 min; the two half-times for elimination averaged approximately 6 and 90 min. Because of between-subject variability, a more accurate description of the time course of toluene uptake and elimination can be provided by kinetic studies that use a within-subject design.

Animals↗
PubMed1976

Characterization of a cell-lethal product from the photooxidation of tryptophan: hydrogen peroxide.

Near-ultraviolet (300 to 400 nanometers) irradiation of saturated, oxygenated solutions of tryptophan in the absence of added sensitizer gives rise to substances that have various biological effects on isolated cells, including mutagenicity and selective lethality to recombination-deficient bacterial mutants. One of these biologically active products has been identified as H2O2, on the basis of spectrometric, chromatographic, chemical, and biological properties. Now H2O2 has been shown to account for the biological activities mentioned above.

Escherichia coli↗