Phencyclidine-induced depressions of cerebellar purkinje neurons

Local administration of phencyclidine (PCP) by pressure ejection elicited a dose-dependent slowing of the spontaneous discharge of cerebellar Purkinje neurons. Ketamine also depressed firing and was much less potent than PCP. Effects of both PCP and ketamine were antagonized by local or parenteral administration of antipsychotic drugs. The similarities between the electrophysiological and behavioral actions of phencyclidine suggest that alterations in neuronal discharge may underlie its psychotomimetic properties.     

Effects of dexamethasone on carnitine metabolism in liver and extrahepatic tissues

The in vivo effects of dexamethasone administration on liver and extrahepatic tissue carnitine concentrations were assessed in 48-h-starved rats. In heart and kidney, but not in liver, dexamethasone significantly increased total carnitine concentration. Acute (2.5 h) treatment with 2-tetradecylglycidate (TDG), a specific inhibitor of carnitine palmitoyl transferase 1, not only increased total hepatic carnitine concentrations, but also permitted an effect of dexamethasone (a further increase in hepatic carnitine concentration). The results are discussed in terms of acute (substrate-mediated) and chronic (hormonal) control of carnitine turnover.     

Magnetic circular dichroism studies on the heme and tryptophan components of cytochrome c peroxidase

We have measured the magnetic circular dichroism of cytochrome c peroxidase and some of its derivatives from 250-350 nm. Comparison of the changes observed on conversion to the catalytic intermediate (cytochrome c peroxidase-I) with spectra obtained from horseradish peroxidase and its derivatives and model compounds of protoheme leads us to the conclusion that the observed changes in the magnetic circular dichroism spectra reflect conversion of the heme to the ferryl state. No evidence was found for modification of tryptophan in cytochrome c peroxidase-I.     

Comparison of Directly Prepared and Cultured Cells in Karyotypic Analysis of All

An evaluation of methods for studying bone marrow obtained from patients with acute lymphoblastic leukemia indicates that both directly prepared and cultured cells are necessary for complete karyotypic analysis, but that both synchronized and unsynchronized cultures may not be necessary.     

Study of two cases of ring 13 chromosome using high-resolution banding.

The chromosomes of two patients with ring 13 (r13) were studied using high-resolution RBG banding of prometaphase cells. The rings of the two patients differ slightly in breakpoints. Cell with multiple single, double-sized rings, quadruple-sized rings, rod- and ring-shaped fragments, and fragments showing varied states of condensation were seen, as were cells monosomic for chromosome 13. The evolution of these cell lines as a result of sister chromatid exchange, nondisjunction, ring breakage, and premature chromosome condensation is discussed. Clinical features of these patients reflect the heterogeneity of phenotype for r13 patients. Each case includes a feature of trisomy 13. The significance of mosaicism of cell lines in patients bearing ring chromosomes is considered with respect to variation in clinical findings.     

Effect of high pH on the spectral and catalytic properties of beef heart cytochrome oxidase

Incubation of cytochrome oxidase at high pH induces changes in several spectral properties. The optical Soret maximum shifts to longer wavelength, and there is an apparent loss in intensity of the 655-nm band, effects that are normally assigned either to a spin-state transition in cytochrome a3 or to a reduction of heme a. However, magnetic circular dichroism spectra show that cytochrome a3 remains high spin and that both cytochrome a and cytochrome a3 are oxidized. At the same time, there is the appearance of a low-spin signal indicative of hydroxide-imidazole coordination which we assign as arising from a structural transition at cytochrome a, rather than at cytochrome a3, as has been proposed previously. With longer incubation times, a new copper signal appears with electron paramagnetic resonance parameters markedly different from those obtained from copper centers which have undergone denaturation. Spin quantitation establishes that this new resonance does not arise from CuA and suggests that high pH breaks the magnetic coupling present at the cytochrome a3-CuB center. A significant proportion of cytochrome a3 may be converted to a low-spin thiolate during this process.     

Toward a unified theory of sexual mixing and pair formation.

Sexually transmitted diseases such as gonorrhea, syphilis, herpes, and AIDS are driven and maintained in populations by epidemiological and sociological factors that are not completely understood. One such factor is the way in which people mix sexually. In this paper, we outline a unified approach to modeling sexual mixing structures, where such structures are defined in terms of a set of axioms for a finite number of distinct groups of people. Theorems for homosexual, heterosexual, and arbitrary group mixing are presented, leading to a representation of all mixing structures defined by the axioms. The representation and its parameters are interpreted in terms of intergroup affinities for sexual mixing. The use of the approach in sexually transmitted disease modeling is discussed.