The effects of mono- and divalent salts on the O2-evolution activity and low temperature multiline EPR spectrum of Photosystem II preparations from spinach

The ability of salts to inhibit the O₂-evolution activity of PS II preparations is shown to parallel closely the Hofmeister series, suggesting that inhibition is related to the solubility of the 16, 24 and 33 kDa proteins in these salt solutions. An examination of the effect of salt inactivation on the low temperature multiline EPR signal indicates that the release of either the 16 and 24 kDa proteins, or additionally the 33 kDa protein blocks or greatly reduces the efficiency of the advancement of the water-splitting complex to the S₂-state; under some conditions, this inhibition is reversible.     

Effects of gender and functional overload on plantaris muscle morphology in the dwarf (HsdOla:dw-4) Lewis rat

To investigate relationships between pituitary function and gender on skeletal muscle growth and hypertrophy, fiber cross sectional area (CSA) and type were assessed in the plantaris muscle of normal and dwarf (Dw) male and female Lewis rats after 6 weeks of functional overload (FO). Serum growth hormone levels were 70-80% less in Dw rats of both genders, and body mass was 62% greater in normal rats when compared to their Dw counterparts. Muscle weight was affected by gender, dwarfism, and FO as well as a significant gender*Dw*FO interaction. FO increased Type I, IIA, and IIX/B fiber CSA 120%, 102%, and 75%, respectively. Only type 1H fibers exhibited a reduction in CSA as a function of gender or dwarfism. Both type IIA and IIX/B fibers were affected by a significant gender*Dw*FO interaction. Our results suggest that the growth of type II fibers is sensitive to gender and pituitary function, while hypertrophy of type II muscle fibers is a function of the interaction between mechanical load, gender, and pituitary function.     

Some contributions of signal detection theory to the analysis of stimulus control in animals

This paper reviews some applications of Signal Detection Theory (SDT) to the quantitative analysis of non-human animal discrimination. The basic detection model is briefly outlined and the separation of sensitivity and bias is illustrated. Several other applications and ideas are reviewed, including the rating method, some implications of signal and criterion variance, and the measurement of 'guesses' not encompassed by standard SDT. The conceptual framework and analytic tools of SDT help to clarify processes underlying stimulus control and provide direction to more complete process models.     

Trace detection of hydroxyl radicals during the redox cycling of low concentrations of diaziquone: a new approach

Quantifying oxygen radicals that arise during the redox cycling of quinone-containing anticancer agents such as diaziquone (AZQ) has been difficult, as has been their detection at low drug concentrations. This is due to the fact that EPR spin trapping, the method most often used for *OH detection, requires the use of high drug concentrations. Using a new highly sensitive technique that employs a fluorescamine-derivatized nitroxide, we show that low levels of NADPH-cytochrome P450 reductase (4.25 microg/ml) catalyze the production of hydroxyl radicals at very low, clinically relevant AZQ concentrations. Thus, at this enzyme concentration, we were able to detect a rate of 0.10 nM s(-1) hydroxyl radical production by 5 microM AZQ, a clinically relevant concentration. The Michaelis-Menten constants for AZQ-mediated hydroxyl radical production are: K(M) = 10.7 +/- 1.4 microM, and V(max) = 5.2 +/- 0.9 x 10(-8) M s(-1) (mg protein)(-1). Experiments employing catalase, superoxide dismutase, and NADPH-cytochrome P450 reductase, confirm the previously deduced conclusions from high drug concentrations, that is, that at low concentrations, AZQ acts to shuttle reducing equivalents from the enzyme to oxygen, thus generating the redox cycle. The data presented here suggest that the levels and locations of redox active metal ions may be the principal controlling factor in the pathway of AZQ activity that involves oxidative stress.     

3alpha-(4-Substituted phenyl)nortropane-2beta-carboxylic acid methyl esters show selective binding at the norepinephrine transporter

A series of 3alpha-(4-substituted)nortropane-2beta-carboxylic acid methyl esters was synthesized and evaluated for the ability to inhibit radioligand binding at the dopamine, serotonin, and norepinephrine transporters. 3alpha-(4-Methylphenyl)nortropane-2beta-carboxylic acid methyl ester (4c) was found to be selective and highly potent for the norepinephrine transporter (NET) relative to the dopamine and serotonin transporters.     

Genomic structure and chromosome location of the murine PDE1B phosphodiesterase gene

Cyclic nucleotide phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP and cGMP, thereby participating in regulation of the intracellular concentrations of these second messengers. The PDE1 family is defined by regulation of activity by calcium and calmodulin. We have cloned and characterized the mouse PDE1B gene, which encodes the 63-kDa calcium/calmodulin-dependent PDE (CaM-PDE), an isozyme that is expressed in the CNS in the olfactory tract, dentate gyrus, and striatum and may participate in learning, memory, and regulation of phosphorylation of DARPP-32 in dopaminergic neurons. We screened an I-129/SvJ mouse genomic library and identified exons 2–13 of the PDE1B gene that span 8.4 kb of genomic DNA. Exons range from 67 to 205 nucleotides and introns from 91 to 2250 nucleotides in length. Exon 1 was not present in the 3 kb of genomic DNA 5′ to exon 2 in our clones. The mouse PDE1B gene shares many similar or identical exon boundaries as well as considerable sequence identity with the rat PDE4B and PDE4D genes and the Drosophila dunce cAMP-specific PDE gene dnc, suggesting that these genes all arose from a common ancestor. Using fluorescence in situ hybridization, we localized the PDE1B gene to the distal tip of mouse Chromosome (Chr) 15. Received: 10 November 1997 / Accepted: 12 March 1998     

556例多发伤患者的急诊救治临床分析

目的探讨多发伤患者的救治策略。方法回顾分析我科2000年1月至2008年5月急诊抢救的556例多发伤患者的临床资料。结果 16例患者经抢救无效死亡,死亡率2.88%;其余患者均经紧急抢救及行必要实验室检查,病情稳定,好转率达97.12%。平均抢救时间为(1.37±1.05)h。结论强化多发伤的急诊科早期救治,树立创伤急救"黄金1 h"观念,是提高多发伤患者生存率及降低死亡率的关键。     

Reaction times in discriminations of varying difficulty: decision modulated by arousal

Pigeons discriminated the hue of a spot of light that appeared in discrete trials. A green spot always signaled food ("green S+") and so did a red spot of constant hue ("red S+"), but on most trials a different red hue appeared and no food was given for pecks ("red S-"). The hue of red S- stayed the same during blocks of up to twelve sessions, but it changed from block to block. During a final group of sessions red S- was omitted and the percent reinforcement to the two S+ stimuli was varied. Major findings were that (1) percent response (Pct(R)) to S- varied with S+/S- similarity, describing a typical ogival psychometric function; (2) Reaction times (RTs) to both red and green S+s were minimal when the red discrimination was impossible (that is, when red S+ and S- were identical); (3) RTs to red S+ were greatest during discriminations of intermediate difficulty; (4) as Pct(R) declined during the learning of a difficult discrimination, RTs increased to red S+ as well as red S-. Most aspects of the data were reproduced by simulations with a quantitative model that incorporated reinforcement-based decision and arousal processes.     

A random-walk interpretation of incentive effects in visual discrimination

Previous studies have shown that changes in stimulus discriminability and changes in reward density affect pigeon reaction-time (RT) distributions in different ways. A random-walk model (“RWP”) accounts for these differences and assigns a single parameter to each of the independent variables. This paper briefly reviews the model and illustrates its findings with hue discrimination data. A new analysis then presents fits to data showing that increased reward for stimulus “A” lengthens RT of pecks to an alternative stimulus “B”, and that this effect on RT distributions is much the same as the effect caused by reduction of reward to B. RWP account for both effects by changes in its “bias” parameter. The remainder of the paper comments on the relations between reward, RT, incentive and bias.