Complexity in seemingly simple sodium magnesiate systems.

A systematic study both in the solid- and solution-state, was carried out for a series of sodium magnesiates containing the utility amide ligand 1,1,1,3,3,3-hexamethyldisilazide (HMDS). The first complex considered is the donor-free bisamido monoalkyl polymeric complex [Na(µ-HMDS)2Mg((n)Bu)]∞ 1. The reactivity of 1 with common tertiary bidentate donors including N,N,N',N'-tetramethylethylenediamine (TMEDA) or its chiral relative (1R,2R)-tetramethylcyclohexyldiamine [(R,R)-TMCDA] is detailed. Surprisingly, the products of these reactions are not simple diamine adducts but are solvent separated sodium magnesiate systems [(TMEDA)2·Na](+)[Mg(HMDS)3](-) 2 and [{(R,R)-TMCDA}2·Na](+)[Mg(HMDS)3](-) 3. By concentrating on the likely equilibria which may give rise to formation of 2, a potential intermediate complexed ion pair [{(TMEDA)2·Na}(µ-(n)Bu)Mg(HMDS)2] 4 was isolated. Additionally, the novel "inverse magnesiates" [{Na(µ-HMDS)}2Mg(µ-(n)Bu)2·(TMEDA)]∞ 5 and [{Na(µ-HMDS)}2Mg(µ-(n)Bu)2·{(R,R)-TMCDA}]∞ 6, were obtained by reacting solutions of composition "NaMg(HMDS)((n)Bu)2" (a likely by-product in the formation of 2 from 1), with TMEDA or (R,R)-TMCDA. The structure and nature of these bimetallic complexes have been determined using a combination of X-ray crystallographic studies and multinuclear NMR spectroscopy.

Single electron transfer (SET) activity of the dialkyl-amido sodium zincate [(TMEDA)·Na(µ-TMP)(µ-tBu)Zn(tBu)] towards TEMPO and chalcone.

More usually thought of as a base, the sodium zincate [(TMEDA)·Na(µ-TMP)(µ-(t)Bu)Zn((t)Bu)] 1 can undergo single electron transfer with TEMPO to give [(TMEDA)·Na(µ-TMP)(µ-TEMPO(-))Zn((t)Bu)] 2 and [(TMEDA)·Na(µ-TEMPO(-))(2)Zn((t)Bu)] 3; and with chalcone [PhCOCH=CHPh] gives [{(TMEDA)·Na(µ-TMP)Zn((t)Bu)}(2)(µ-OCPhCH=CHPhCHPhCH=CPh-µ-O)] which contains two chalcone units C-C coupled though their benzylic C atoms.

A closer look at amphetamine-induced reverse transport and trafficking of the dopamine and norepinephrine transporters.

Amphetamine (AMPH) and its derivatives are regularly used in the treatment of a wide array of disorders such as attention-deficit hyperactivity disorder (ADHD), obesity, traumatic brain injury, and narcolepsy (Prog Neurobiol 75:406-433, 2005; J Am Med Assoc 105:2051-2054, 1935; J Am Acad Child Adolesc Psychiatry 41:514-521, 2002; Neuron 43:261-269, 2004; Annu Rev Pharmacol Toxicol 47:681-698, 2007; Drugs Aging 21:67-79, 2004). Despite the important medicinal role for AMPH, it is more widely known for its psychostimulant and addictive properties as a drug of abuse. The primary molecular targets of AMPH are both the vesicular monoamine transporters (VMATs) and plasma membrane monoamine-dopamine (DA), norepinephrine (NE), and serotonin (5-HT)-transporters. The rewarding and addicting properties of AMPH rely on its ability to act as a substrate for these transporters and ultimately increase extracellular levels of monoamines. AMPH achieves this elevation in extracellular levels of neurotransmitter by inducing synaptic vesicle depletion, which increases intracellular monoamine levels, and also by promoting reverse transport (efflux) through plasma membrane monoamine transporters (J Biol Chem 237:2311-2317, 1962; Med Exp Int J Exp Med 6:47-53, 1962; Neuron 19:1271-1283, 1997; J Physiol 144:314-336, 1958; J Neurosci 18:1979-1986, 1998; Science 237:1219-1223, 1987; J Neurosc 15:4102-4108, 1995). This review will focus on two important aspects of AMPH-induced regulation of the plasma membrane monoamine transporters-transporter mediated monoamine efflux and transporter trafficking.

Development of bimanual skill: the search for stable patterns of coordination.

In 2 experiments, dynamic systems theory predictions concerning intrinsic dynamics and variability of bimanual coordination were examined at different developmental stages. In Experiment 1, ten 4-, 6-, 7-, 8-, and 10-year-old children and adults performed unimanual dominant, unimanual nondominant, and bimanual continuous circle drawing. All tasks were performed at the participants' preferred rate, size, and mode of coordination. The 4-, 6-, and 7-year-old children produced larger circles with longer durations than those of the 8- and 10-year-olds and the adults. That finding demonstrates that younger children display different intrinsic dynamics than older children and adults. The 4-, 6-, and 7-year-old children also displayed more variability in bimanual coordination (more time in less stable patterns of coordination, higher standard deviation in relative phase) and produced more transitions between coordination patterns than the 8- and 10-year-olds and the adults. In Experiment 2, the same participants performed bimanual circles at increasing rates. Consistent with predictions of the HKB model (H. Haken, J. A. S. Kelso, & H. Bunz, 1985), the number of transitions decreased as speed increased. Some support was found for the notion that age-related variables of attention and rate contribute to the increased variability in young children's bimanual coordination.

An unusual case of aortic dissection in Turner's syndrome.

Cardiovascular malformations are common in patients with Turner's syndrome. Aortic coarctation and bicuspid aortic valve are the most frequently occurring abnormalities, and are associated with cystic medial necrosis of the aortic wall. Aortic dissection is an uncommon but catastrophic complication of the 'aortopathy' of Turner's syndrome. We report the unusual case of a Turner's syndrome patient (with a bicuspid aortic valve and previous coarctation repair) who died following an intramural haemorrhage of the aortic root that was complicated by dissection and rupture, with no evidence of aortic intimal tear. The role of intramural haemorrhage in the pathogenesis of acute aortic syndromes in Turner's syndrome patients is unclear. The condition may be associated with atypical clinical presentations, it can be difficult to confirm with imaging techniques, and it carries a high risk of progression to classical aortic dissection and death. This case therefore highlights the need for a high index of suspicion when assessing Turner's syndrome patients presenting with chest pain syndromes. Furthermore, the effective management of Turner's syndrome patients with cardiovascular abnormalities requires the development of evidence-based preventive (such as echocardiographic surveillance of aortic dilatation) and interventional strategies.

Issues in child homicides: 11 cases.

For a variety of reasons, child homicides are the most difficult cases for forensic pathologists. For example, the events are usually not witnessed, accidental explanations are offered, often there is more than one carer spanning the period over which the injuries might have occurred and there can be conflicting opinions between the various medical specialities. Eleven cases of fatal child abuse are presented to illustrate and briefly discuss particular difficulties. Reference is also made to interaction with the legal process and parallel difficulties the law has with fatal child abuse.

Correlations for timing consistency among tapping and drawing tasks: evidence against a single timing process for motor control.

Three experiments were conducted to examine whether timing processes can be shared by continuous tapping and drawing tasks. In all 3 experiments, temporal precision in tapping was not related to temporal precision in continuous drawing. There were modest correlations among the tapping tasks, and there were significant correlations among the drawing tasks. In Experiment 3, the function relating timing variance to the square of the observed movement duration for tapping was different from that for drawing. The conclusions drawn were that timing is not an ability to be shared by a variety of tasks but instead that the temporal qualities of skilled movement are the result of the specific processes necessary to produce a trajectory. These results are consistent with the idea that timing is an emergent property of movement.

Cytogenetic damage in marrow cells of mice after injections of yttrium-90-labeled monoclonal antibody.

Chromosome aberrations, micronuclei and sister-chromatid exchanges were quantified in marrow cells of athymic nude and B6C3F1 mice at various times up to 14 days after injection of 90Y-labeled monoclonal antibody CO17-1A. Aberrations, predominantly of the chromatid type, were sharply elevated at 24 h post-injection then declined in a curvilinear fashion over the 14 days. Micronucleus numbers among polychromatic erythrocytes peaked 3-4 days after treatment, then declined exponentially but remained at higher than expected levels. Sister-chromatid exchanges were roughly double the control rate with no apparent relation to post-treatment time.