Search Results - (Author, Cooperation:R. L. Collins)

2015-03-26

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Autistic Disorder/*genetics/*metabolism ; Brain/embryology/*metabolism ; Catenins/*deficiency/*genetics/metabolism ; Cells, Cultured ; Chromatin/genetics/metabolism ; DNA Copy Number Variations/genetics ; Embryo, Mammalian/cytology/metabolism ; Exome/genetics ; Female ; Gene Expression ; Gene Expression Regulation, Developmental ; Hippocampus/pathology ; Humans ; Male ; Mice ; Models, Genetic ; Multifactorial Inheritance/genetics ; Mutation, Missense ; Nerve Net ; Neurons/cytology/metabolism ; Sex Characteristics ; Zebrafish/embryology/genetics/metabolism

2018-12-14

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Development, Genetics, Neuroscience, Online Only

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Attempts to synthesize ferrous ferricyanide always produced a material similar to Prussian blue, although the name Turn-bull's blue was associated with the compound3'4. An internal redox apparently occurs, and the electron moves from cation to anion. The effect of a mild vacuum pyrolysis is ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] IT is generally accepted that genetic factors must play a key part in ageing and in determining the life-span of an organism. However, since the average life-span in a selected population can vary in accordance with some extreme environmental fluctuations, it has seemed equally plausible to assume ...

Electronic Resource

1432-0703

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Medicine

Abstract The available concentration of a slowly released, biologically active substance is the result of the interplay of the processes of release and of decay. In this paper, the theory of the release mechanisms based on diffusion and, also, on water-degradable polymers is examined in detail, and, based on a first-order decay of the released substance, the “present concentration” based on area is calculated. The attainment and maintenance of a constant present concentration over a chosen time period is considered as the ideal. The actual, long-term efficiencies which can be expected vary from 22% for diffusion to 100% for a well-chosen combination of water-degradable polymers and conventional substances. The efficiency varies conversely with toxicity; so, safety and efficiency are simultaneously attainable. The major benefits of controlled release appear only for times encompassing several half-lives of the active substance. This finding encourages the consideration of non-persistent pesticides.

Electronic Resource

1432-2072

Key words Behavioral sensitization ; U-50 ; 488 ; Kappa opioid ; Locomotor activity ; Fos ; Ontogeny

Springer Online Journal Archives 1860-2000

Medicine

Abstract  When given acutely, drugs that stimulate kappa opioid receptors (e.g., U-50,488) enhance the locomotor activity of preweanling rats and induce regional increases in Fos immunoreactivity (IR). In contrast, the effects of chronic treatment with kappa opioid agonists are unknown. The purpose of the present study was two-fold: first, to determine whether repeated treatment with a kappa opioid agonist would sensitize the locomotor activity of preweanling rats and, second, to determine whether changes in Fos IR correspond with the occurrence of locomotor sensitization. To test these hypotheses, rats were injected with U-50,488 (5 mg/kg, SC) or saline on either postnatal days (PD) 5–9 or PD 11–15. For rats pretreated on PD 5–9, a test day injection of U-50,488 or saline was given after either 1 or 7 abstinence days (i.e., at PD 11 or PD 17). For rats pretreated on PD 11–15, a test day injection of U-50,488 or saline was given after 1 abstinence day (i.e., at PD 17). In two additional experiments, the acute and chronic effects of U-50,488 treatment were assessed in adult rats. As expected, repeated treatment with U-50,488 produced locomotor sensitization at both PD 11 and PD 17, but only when the test day occurred 1, and not 7, days after cessation of drug pretreatment. Thus, the persistence of the sensitized response was very brief. Test day treatment with U-50,488 stimulated Fos IR in various brain regions of the preweanling rat, including the medial striatum, nucleus accumbens, lateral habenula, and septal area. Chronic treatment with U-50,488 depressed Fos expression in a number of brain regions (relative to acutely treated rats); however, these changes in Fos IR did not necessarily coincide with the occurrence of behavioral sensitization. Repeated treatment with U-50,488 did not produce locomotor sensitization in adult rats, so Fos IR was not assessed in this age group. Therefore, while acute treatment with U-50,488 both increased locomotor activity and stimulated Fos IR in preweanling rats, chronic U-50,488 treatment produced behavioral changes that did not correspond with Fos expression.

Electronic Resource

1432-2072

Key words Methylphenidate ; Behavioral sensitization ; Sniffing ; Locomotor activity ; Adenylyl cyclase ; Protein kinase A

Springer Online Journal Archives 1860-2000

Medicine

Abstract  The behavioral effects of repeated methylphenidate (MPH) treatment were assessed in the adult rat. Protein kinase A (PKA) and adenylyl cyclase (basal and DA-stimulated) activity in the dorsal striatum (i.e., caudate-putamen) were measured to determine whether MPH-induced alterations in these enzymes correlate with the occurrence of behavioral sensitization. In two experiments, adult rats were injected (IP) on 5 consecutive pre-exposure days with saline or MPH (5, 10, 15, or 20 mg/kg). Sensitization was tested after a single abstinence day, with rats receiving a challenge injection of MPH prior to either a 40- or 150-min testing session (additional control groups received saline on the test day). Immediately after the 40-min testing session, rats were killed and tissue from the dorsal striatum was dissected for later analysis of PKA and adenylyl cyclase activity. Results showed that repeated MPH treatment sensitized the stereotyped sniffing, but not the locomotor activity, of adult rats. PKA activity was significantly depressed in rats treated with MPH (10 or 20 mg/kg) during both the pre-exposure and test day phases. DA-stimulated adenylyl cyclase activity was reduced after chronic MPH treatment, while basal adenylyl cyclase values were enhanced. Thus, the present study showed that MPH was able to sensitize the stereotyped behaviors of adult rats, an action that corresponded with drug-induced changes in dorsal striatal DA signal transduction mechanisms.

Electronic Resource

1572-9540

Springer Online Journal Archives 1860-2000

Physics

Electronic Resource

0022-3832

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

The proton spin resonance spectrum of polyethylene consists of two superimposed lines. The narrow line is attributed to the amorphous phase, and the broad line to the crystalline phase. The width of the narrow line was measured at various temperatures from 25-130°C. for Alathon 10, Alathon 14, DYNH, and Marlex 50 polyethylene and it was found to vary with temperature. The results have been interpreted using the theory of motional narrowing, which indicates that the product of temperature and line width is proportional to the viscosity. A plot of log of line width times temperature versus reciprocal temperature is linear for Marlex 50 polyethylene, and is curved for the other three. The linearity is believed due to the simple structure of the material, and the slope yields an activation energy of 8200 cal./mole. The curvature of the other data is believed due to extensive branching which causes a change of composition of the amorphous phase upon cooling, and the apparent activation energy varies from 11,800 cal./mole at 130°C. to 4900 cal./mole at 25°C.

2 Ill.

Electronic Resource

0022-3832

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

The effect of time and temperature on the crystalline recovery of quenched Marlex 50 polyethylene has been investigated. Quenching thin films in ice water reduced the room temperature crystallinity from a normal value of 93 to 82%. These specimens were maintained at 25, 66.2, and 106.4°C., and the time variation of crystallinity was followed by nuclear spin resonance. The crystalline recovery appears to follow the empirical formula, X = A + B log t, where X is the percentage crystallinity and t, is the time in hours. The rate, X, increases with temperature. The temperature-dependence of B was computed by assuming the rate to be controlled by diffusion in the amorphous phase. The temperature-dependence of diffusion is determined by nuclear spin resonance line width measurements to be exp {-8700/RT}. The rate is then X = C/t exp {-8700/RT}, and C, evaluated at 25, 66.2, and 106.4°C., is 2.2 ± 1.9, 1.7 ± 0.5, and 2.1 ±0.2 × 105. This agreement is within the probable error, and justifies the assumption of diffusion as the rate-controlling factor. The result is X = 2.04 × 105(1/t) exp { -8700/RT} and X = A + 4.70 × 105 log t exp {-8700/RT}.

2 Ill.

Electronic Resource