Synthesis, Characterization, and Catalytic Exploration of Mononuclear Mo(VI) Dioxido Complexes of (Z)-1-R-2-(4',4'-Dimethyl-2'-oxazolin-2'-yl)-eth-1-en-1-ates.

The coordination chemistry of the title ligands with Mo metal centers was investigated. Thus, the synthesis and characterization (NMR, X-ray diffraction) of four mononuclear formally Mo(6+) complexes of (Z)-1-R-2-(4',4'-dimethyl-2'-oxazolin-2'-yl)-eth-1-en-1-ates (L: R = -Ph, -Ph-p-NO2, -Ph-p-OMe and -t-Bu), derived from the part enols (LH), is described. The resulting air-stable MoO2L2 complexes (1-4) exist, as shown by single-crystal X-ray diffraction experiments, in the cis-dioxido-trans(N)-κ2-N,O-L conformation in the solid state for all four examples. This situation was further probed using semi-empirical PM6(tm) calculations. Complexes 1-4 represent the first Mo complexes of this ligand class and, indeed, of Group 6 metals in general. Structural and spectroscopic comparisons were made between these and related Mo(6+) compounds. Complex 1 (R = -Ph) was studied for its ability to selectively catalyze the production of poly-norbornene from the monomer in the presence of MAO. This, unfortunately, only resulted in the synthesis of insoluble, presumably highly cross-linked, polymeric and/or oligomeric materials. However, complexes 1-4 were demonstrated to be highly effective for catalyzing benzoin to benzil conversion using DMSO as the O-transfer agent. This catalysis work is likewise put into perspective with respect to analogous Mo(6+) complexes.

An actuatable soft reservoir modulates host foreign body response.

The performance of indwelling medical devices that depend on an interface with soft tissue is plagued by complex, unpredictable foreign body responses. Such devices-including breast implants, biosensors, and drug delivery devices-are often subject to a collection of biological host responses, including fibrosis, which can impair device functionality. This work describes a milliscale dynamic soft reservoir (DSR) that actively modulates the biomechanics of the biotic-abiotic interface by altering strain, fluid flow, and cellular activity in the peri-implant tissue. We performed cyclical actuation of the DSR in a preclinical rodent model. Evaluation of the resulting host response showed a significant reduction in fibrous capsule thickness (P = 0.0005) in the actuated DSR compared with non-actuated controls, whereas the collagen density and orientation were not changed. We also show a significant reduction in myofibroblasts (P = 0.0036) in the actuated group and propose that actuation-mediated strain reduces differentiation and proliferation of myofibroblasts and therefore extracellular matrix production. Computational models quantified the effect of actuation on the reservoir and surrounding fluid. By adding a porous membrane and a therapy reservoir to the DSR, we demonstrate that, with actuation, we could (i) increase transport of a therapy analog and (ii) enhance pharmacokinetics and time to functional effect of an inotropic agent. The dynamic reservoirs presented here may act as a versatile tool to further understand, and ultimately to ameliorate, the host response to implantable biomaterials.

Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers.

The synthesis and solid-state molecular structures of two dichlorido(aryl)(alkyl) tin compounds, 5 and 8, both key intermediates to tunable polystannane architectures, are reported. The materials were further investigated by single-crystal XRD and a DFT analysis of their preferential "open and closed" geometries. Conversion of said compounds to their dihydride analogues was undertaken, followed by their application as monomers for polystannane polymer synthesis. The properties of two asymmetrical polystannanes prepared by transition-metal-catalyzed dehydropolymerization of dihydrido(aryl)alkylstannanes (6 and 9) were investigated. The first product was the structurally simple, modest molecular weight, semi-crystalline light- and moisture-stable polystannane 10 with NMR (119 Sn) evidence of prominent Sn←O hypercoordination along the polymer backbone. The second was the lower molecular weight, tosylated four-coordinate polystannane 11 with no evidence of hypercoordination. Differential scanning calorimetry (DSC) of polymer 10 revealed a reversible semi-crystalline nature, whereas an amorphous character was detected for polymer 11. Polystannane 10 was also found to be exceptionally stable to both moisture and light (>6 months) and a promising candidate for the design of readily modified (i.e., tunable) polystannane materials.

Proof of Concept Studies Directed Towards Designed Molecular Wires: Property-Driven Synthesis of Air and Moisture-Stable Polystannanes.

Polystannanes with azobenzene moieties designed to protect the Sn-Sn backbone from light- and moisture-induced degradation are described. The azo-stannyl precursor 3 (70 %) is converted in good yields (88-91 %) to the mono- (4), and dichlorostannanes (5), by sequential chlorination, followed by further reduction of 5 to the dihydride (6) using NaBH4 (78 %). All stannanes were characterised by NMR (1 H, 13 C, 119 Sn) spectroscopy and HRMS; in addition, 3, 4 and 5 were structurally elucidated using X-ray diffraction analysis. Metal-free dehydrocoupling of 6 at RT leads exclusively to homopolymer (7-i) displaying an initial solution 119 Sn NMR signal (δ=-196 ppm) that migrates to -235 ppm after 10 days (7-f). In contrast, metal-catalyzed dehydrocoupling of 6 in toluene at RT leads directly 7-f. Random co-polymers formed from 6 and (nBu)2 SnH2 at 4:1 (8 a) and 1:1 (8 b) ratios were compared to the alternating polystannane (9) prepared by the reaction of 6 with (nBu)2 Sn(NEt2 )2 . DFT calculations of 3-6 indicate that hypercoordination at Sn is influenced by substituents and by solvation. Homopolymer 7 was found to have unprecedented moisture and light stability in the solid state for >6 months.

Tautomerism and metal complexation of 2-acylmethyl-2-oxazolines: a combined synthetic, spectroscopic, crystallographic and theoretical treatment.

A synthetic, structural and theoretical investigation into the solid-state, solution and gas phase structure(s) of six 2-acylmethyl-4,4-dimethyl-2-oxazolines is reported. Four of these materials, viz.α-[(4,5-dihydro-4,4-dimethyl-2-oxazolyl)methylene]benzenemethanol (3a), α-[(4,5-dihydro-4,4-dimethyl-2-oxazolyl)methylene]-(4-nitrobenzene)methanol (3b), 1-(4,5-dihydro-4,4-dimethyl-2-oxazolyl)-3,3-dimethyl-1-buten-2-ol (3d) and (E)-1-phenyl-2-((3aR)-3,3a,8,8a-tetrahydro-2H-indeno[1,2-d]oxazol-2-ylidene)ethanone (3f) have been characterised in the solid-state by single crystal X-ray diffraction studies. These data represent the first solid-state structural studies of this class of compounds and details the first synthesis and full characterisation of chiral derivative 3f. All four of these materials are shown to exist in the solid phase in the enamine tautomeric form (e.g., 3a is best described as 2-[4,4-dimethyl-2-oxazolidinylidene]-1-phenylethanone) and it is suggested (NMR, IR) that this isomeric form is likely also retained in solution (e.g., CDCl3) as the more stable isomer. An investigation of the relative gas phase stabilities of the three possible (i.e., the (Z)-enol, keto and enamine) isomers of all five compounds by DFT at the B3LYP/6-311G(d) level of theory confirms the latter as the most stable form. The energy differences between the enamine and keto tautomers have been calculated to be the lowest for derivative 3d. These results are compared and contrasted with the previously reported NMR studies of such compounds which have identified the keto form as being a minor (albeit solution) tautomer. Equilibrium solution tautomer distributions for 3d are found to be solvent dependent. The protonated form of 3a, isolated as the HSO4(-) salt (i.e.4a), has been further characterised in the solid state by single crystal X-ray diffraction. These data represent the first example of a protonated oxazoline to be structurally elucidated and confirms that upon protonation, the keto (oxazoline) tautomer is the energetically favoured form in the solid-state. This observation is further supported by DFT studies for the gas phase protonated forms of such materials. Further DFT (B3LYP/6-311G(d)) calculations employing the SM8 or SMD solvation models were then applied to address the observed solution isomeric distribution for 3d; these results corroborate the gas phase theoretical treatment and also yield values that predict the higher solution stability of the enamine form as observed, although they fail to account for the existence of the keto form as a minor solution state tautomer. To access the availability of an enol-form, via hypothetical de-protonation to the enolate, compound 3a was treated with hydrated Cu(NO3)2 in EtOH solution. The resulting isolated green-coloured product (5), the first metal derivative of this entire class of ligands, is best described (IR, X-ray diffraction) as a coordinated enolate complex, i.e., Cu(3a-H)2. Complex 5 crystallizes in the P21/c space group with four molecules in the unit cell. The coordination geometry around the formal Cu(2+) metal centre is determined to be highly distorted square planar in nature (τ4 = 0.442). TD-DFT is used to give a reasonable explanation for the intensity of the absorbance band observed in the visible region for solutions of 5. These latter experiments strongly suggest that the title class of compounds may have considerable potential as ligands in coordination chemistry and/or metal-mediated catalysis.

Unusual cationic trinuclear nickel clusters incorporating oxazolines or N,N,N',N'-tetramethylethylene-1,2-diamine: applications in olefin polymerization.

The synthesis and characterization of two rare examples of the nickel(II)-containing trinuclear clusters of the general formula µ(3)-halido-µ(3)-hydroxotris(µ-halido)tris(L) trinickel(II) halide [halide = Cl (2), Br (3); L = 4,4-dimethyl-2-(o-anilinyl)-2-oxazoline] are described. These materials are compared and contrasted to the "parent" chloride salt (1) of this series (L = N,N,N',N'-tetramethylethylene-1,2-diamine and halide = Cl) and its congeners; 2 and 3 represent the first oxazoline-containing clusters of this structural class. Both 1 and 2 are shown to be active catalysts for the polymerization of olefins (styrene, methyl methacrylate, etc.) using a stoichiometric equivalent of methylaluminoxane as the copromoter, a situation that gives good yields of syndiotactic rich polymers. Density functional theory (B3LYP/6-31G*/LANL2DZ) is employed to hypothesize the likely origin of the activity demonstrated by these compounds.

Equine amnionitis and fetal loss: the case definition for an unrecognised cause of abortion in mares.

A series of abortions occurred in mares in New South Wales during 2004 that involved similar and unusual findings on post mortem examination of aborted fetuses and fetal membranes. The term Equine Amnionitis and Fetal Loss (EAFL) was developed to describe the condition. This form of abortion had not been previously recognised in Australia. The pathology alone is not specific for EAFL and diagnosis requires demonstration of a combination of certain pathological and bacteriological features. The purpose of this paper is to describe patterns considered consistent with EAFL cases as a working case definition for use by veterinarians and veterinary pathologists in identifying future cases of EAFL. More detailed papers are in preparation to fully describe the epidemiological, histopathological, and microbiological aspects of EAFL.

The Child Protection Register: a tool in the accident and emergency department?

AIMS: To determine the number of children on the Child Protection Register (CPR) attending the accident and emergency (A&E) department and the referral source, diagnostic category, and frequency distribution for such attendances. To determine whether lack of knowledge that a child is on the CPR results in failure to suspect non-accidental injury (NAI) if the standard indicators of NAI have been sought. METHODS: Access to the CPR was obtained. Records of each child attending the A&E departments of the United Hospitals Trust between June 1994 and May 2000 were reviewed. RESULTS: Over the six years 191 children were on the CPR. Seventy nine (41%) attended A&E departments on 206 occasions. Frequency of attendance ranged to 18 with a mean of 2.6. Self referral was the commonest source of referral (81%) followed by general practitioners (13%), 999 calls (5%), and a small number from schools (1%). Most presentations involved trauma-upper limb (21%), lower limb (14%), and head injury (8%). Almost all cases of trauma were adjudged to be consistent with the history and NAI not suspected. Common childhood illnesses accounted for the remainder of presentations. Only six children were identified as being on the CPR at the time of presentation. Concerns were raised in two other cases and concerns should have been raised in three other children. Social Services were alerted on five occasions directly by the parents themselves. CONCLUSIONS: It is concluded that in the absence of knowledge of the status of a child on the CPR attending the A&E department, that screening for the standard indicators of NAI is adequate to detect most cases of NAI.

Effects of periodontal support and fixed splinting on load transfer by removable partial dentures.

STATEMENT OF PROBLEM: Periodontally compromised abutment teeth complicate the design of bilateral distal extension removable partial dentures. PURPOSE: This study investigated the stress induced in the remaining oral structures by a bilateral distal extension I-bar-retained RPD with periodontally involved abutments in a photoelastic simulation model. MATERIAL AND METHODS: Composite photoelastic models were used as a simulation model in determining the stress generating characteristics of I-bar RPDs with varying degrees of periodontal involvement of the distal abutments. Effects of fixed splinting were considered. RESULTS AND CONCLUSIONS: Under the same load conditions, the highest stresses developed in the model with the largest osseous defect. Increasing the number of splinted teeth did not provide a proportional decrease in maximum stress levels. The more severe the osseous defect, the greater assistance was provided by splinting to periodontally sound teeth. This simulation study suggests that routine cross-arch splinting may not be appropriate.

Effects of the serotonin agonists 8-OH-DPAT, buspirone, and DOI on water maze performance.

We have previously reported that the serotonin 5-HT1A agonist 8-OH-DPAT and the 5-HT2c agonist TFMPP impair performance on a water maze. In the present report we extended those studies by examining a second 5-HT1A agonist, buspirone, to see whether its effects paralleled those of 8-OH-DPAT, and by testing the effects of the 5-HT2 agonist DOI. Unlike the open pool Morris water maze, the maze used in these experiments has alleys and doorways. The maze can be easily reconfigured to present rats with both previously learned or new maze challenges. Performance is assessed by time to reach the maze exit platform and the number of wrong doorways entered (errors). At doses that did not affect performance in a previously learned maze, the 5-HT1A agonists 8-OH-DPAT (0.1 mg/kg) and buspirone (1 mg/kg) slowed acquisition of a new maze configuration as measured by both swim time to the exit platform and errors committed. A higher dose of buspirone (10 mg/kg) completely blocked acquisition of a novel maze. In contrast. DOI slowed performance as assessed by swim time on both a well-learned maze as well as acquisition of a new maze, but did not affect error rate on either task, suggesting that this 5-HT2 agonist impaired performance by depressing motor activity. These experiments demonstrate that serotonin agonists, especially the 5-HT1A subtype, can impair learning.

Oral health education for medical students.

With a view to improving oral health in Oman, particularly in the interior of the country where dental services are very scarce, medical students have been receiving a grounding in this field since 1988. The results achieved so far have proved encouraging.

Effects of triazolam and diazepam on learning and memory as assessed using a water maze.

One of the reported adverse side effects of the frequently prescribed benzodiazepines diazepam (Valium) and triazolam (Halcion) is an impairment of anterograde memory in humans. The experiments described in this article compared the effects of triazolam and diazepam on performance in a water maze task that is sensitive to drugs that affect learning and memory. The water maze utilized is a traditional type of maze with alleyways and door choices, unlike the Morris open water maze. Time required to find an out-of-the-water platform and errors committed during the swim are used as performance measures. Rats were tested on a previously learned maze configuration and on the acquisition of new maze configurations. Neither diazepam (0.25, 1.0, or 2.0 mg/kg) nor triazolam (0.05, 0.2, or 0.3 mg/kg) injected 30 min prior to testing on the previously learned maze affected swim time or errors committed. Administration of diazepam (0.5, 1.0, or 2.0 mg/kg, IP) prior to daily training on three different new maze configurations did not affect swim time, but did increase swim errors. Triazolam administered at 0.1, 0.2, or 0.3 mg/kg markedly impaired performance as assessed by either swim time or errors. There were no differences in performance of rats previously treated with triazolam, diazepam, or vehicle in learning another new maze after drug treatment was terminated. These data demonstrate that both diazepam and triazolam affect acquisition but not recall of maze configurations and support similar conclusions reached using other types of tasks in humans and animals.

Discriminant analysis of macrocytic red cells.

Laboratory classification of red cell disorders uses the red cell indices (MCV, MCH, MCHC, RDW) and information gleaned from microscopic evaluation of a blood film. Additional red cell information is now available using the H series of automated blood cell analysers (Ames Technicon Division of Bayer Diagnostics). This study involved the development of a discriminant rule which would differentiate between three causes of macrocytosis (vitamin B12/folate deficiency, alcohol excess/liver disease and a reticulocytosis) using the information available on Research Screen 1 and Report Screen 3 of the H*1 instrument (Report Screen 3 is a graphical display of the trimmed scattergram of red cell volume and red cell haemoglobin concentration and Research Screen 1 displays the associated numerical data). Three methods of analysis were assessed to define a suitable discriminant rule. The percentages of patients correctly classified by the three methods were: 92.1%, 82.0% and 89.2% for Methods 1, 2 and 3 respectively. Method 1 involved the application of quadratic discrimination to transformed variables and produced the best results. Although complex, it could easily be applied using the microprocessor capability of the average multiparameter haematology analyser.

Fixed cantilever splints on teeth with normal and reduced periodontal support.

Photoelastic models were used to visualize stresses developed in teeth and supporting bone by cantilever fixed partial dentures where the most distal abutments had either crater or trough osseous defects. The effects of splinting the periodontally involved teeth to one or more additional sound teeth were studied. It was shown that for a cantilever fixed partial denture with either normal periodontal support, or a distal abutment with a moderate degree of mobility and bone loss, the following can be concluded: (1) occlusal forces on a cantilever fixed partial denture were significantly distributed to only the three teeth closest to the loaded cantilever, (2) optimum stress reduction occurred with the splinting of a periodontally compromised tooth to two periodontally sound teeth. Increasing the number of splinted abutments did not result in a proportional reduction of stress in the periodontium, and (3) no significant cross-arch sharing of occlusal loads was seen.

Sanguinarine levels in biological samples by high-performance liquid chromatography.

A high-performance liquid chromatographic method is presented for the analysis of the benzophenanthridine alkaloid, sanguinarine, found in plant extracts. The method is demonstrated to be applicable to analyzing samples such as saliva and gingival crevicular fluid for sanguinarine following a simple acidified methanolic extraction step. The method utilizes an ethyl silane column with acidic and basic ion-pairing reagents in the mobile phase with a limit of detection of 3 ng of sanguinarine in a sample.

Mothers' attributions to their young children: the verbal environment as a resource for children's self-concept acquisition.

There has been a century of theorizing that self-conceptions begin to develop early, heavily involve language, are important aspects of personality, and are much influenced by others' reactions. Nevertheless, no one has heretofore probed the empirical characteristics and antecedents of mothers' language that might be relevant to their 2 1/2-year-old children's acquisition of self-conceptions. In this research, such "maternal attributions" were located in video transcripts of 3 mother-child pairs, each interacting for 300 minutes (Study 1), and of 35 mother-child pairs, each interacting for 35 minutes (Study 2), all in a seminaturalistic setting. Study 2 replicated and extended results from Study 1 regarding (a) types of occasion for maternal attributions; and (b) the attributions' specificity/abstractness, vocabulary content, substantive referent, explicitness/implicitness, evaluative tone, and direction toward the whole child or an aspect of the child. Antecedent-consequent relationships were found between children's roles in occasioning attributions and the language specificity and evaluative tone of the attributions. Results are discussed in terms of the development of the self.

Epidermoid cyst of the spleen: a clinico-pathologic correlation.

A large epidermoid cyst of the spleen in a 39-year-old woman is reported. Diagnosis and treatment are discussed. Epidermoid cysts of the spleen occur in newborns, children and adults up to 50 years of age, with the peak incidence in the second and third decades. Abdominal mass, discomfort and non-specific gastrointestinal complaints are most common clinical presentations. Radionuclide imaging, computed tomography and sonography are the preferred preoperative noninvasive diagnostic methods.

The history, chemistry and pharmacokinetics of Sanguinaria extract.

Sanguinaria extract is a mixture of benzophenanthridine alkaloids derived from Sanguinaria canadensis L. (bloodroot). This mixture of alkaloids has a long history of use in tinctures and expectorants in pharmaceutical products. The purity of Sanguinaria extract is well defined. The chemistry and biochemistry of these alkaloids, including the dynamic equilibrium between acid and base forms, and pharmacokinetics of Sanguinaria extract shall be presented when this extract is incorporated into a dentifrice or oral rinse formulation.

Performance of a weight-lifting task by normal and deafferented monkeys.

The role of topographic information from a moving limb in controlling the trajectory of the limb was explored by comparing the ability of 3 normal and 2 unilaterally deafferented monkeys to generate criterion elbow flexions when opposed by different weights. When lifting initially unknown weights, both groups of monkeys reached maximum positions that were inversely related to load. The performance of the deafferented monkeys approached that of the normal monkeys on these first lifts of initially unknown weights. The preceding load had a greater effect on the initial lifts of the deafferented monkeys than on those of the normal monkeys. When allowed to repeatedly lift the same weight, both groups obtained a high density of reinforcement, but the responses of the deafferented monkeys were more dependent on the weight. The results are consistent with the hypothesis that the mechanical properties of muscle make an important contribution to compensation.