Alpha'-hydroxyenones as mechanistic probes and scope-expanding surrogates for alpha,beta-unsaturated aldehydes in N-heterocyclic carbene-catalyzed reactions

N-heterocyclic carbene-catalyzed reactions of alpha,beta-unsaturated aldehydes and a variety of electrophiles allow the facile preparation of a diverse array of annulation products including trisubstituted cyclopentenes, gamma-lactams, and bicyclic beta-lactams. The substrate scope of these reactions, however, is limited by the difficulties of preparing the starting alpha,beta-unsaturated aldehydes. We now report that alpha'-hydroxyenones, which can be prepared in a single convenient step from aromatic and heteroaromatic aldehydes, can serve as efficient surrogates for enals in the annulation reactions. This protocol allows the facile preparation and use of substrates bearing nitrogen heterocycles. These reagents have also allowed us to demonstrate that, in contrast to other classes of aldehydes, the formation of the Breslow intermediate from enals and N-heterocyclic carbenes is irreversible under the reaction conditions.

On the role of CO2 in NHC-catalyzed oxidation of aldehydes

NHC-catalyzed oxidations using carbon dioxide as the stoichiometric oxidant have been carefully investigated. These studies support a secondary role of CO(2) in suppressing side reactions and exogenous oxygen as the actual oxidant.

Mechanical properties of rat skeletal muscle after hind limb suspension

It is clear that there are events which occur in response to neuromuscular activity that are essential to maintain normal muscle properties. Two factors though to influence muscle contractile properties are tension and electrical activity. To study these variables the hind limbs of 10 postpubertal female Sprague-Dawley rats were prevented from supporting the weight of the body for 4 weeks, then in situ isometric properties were determined and compared with 10 age-matched control rats. The soleus (slow plantarflexor), the medial gastrocnemius (fast plantarflexor), and the tibialis anterior (fast dorsiflexor) were studied. The suspended soleus wet weight was 42% lower and the maximum isometric twitch (Pt) and tetanic (P0) tensions were 62 and 69% lower respectively, than in the control rats. The suspended medial gastrocnemius was 18% lower in wet weight and 14 and 9% lower in P0 and Pt than the controls. No differences in wet weight, P0 or Pt were observed in tibialis anterior. Mean contraction time was 22% shorter in the soleus, 9% in the medial gastrocnemius, and unchanged in the tibialis anterior following suspension. Further, the percent of P0 attained during a 330-ms tetanus at 20 Hz was 15% lower in the suspended soleus and unchanged in the other two muscles. The fatigue index (ratio of tension after 2 min of stimulation at 40 Hz for 330 ms once per second to the maximum tension developed during the test) was unaffected by suspension in the soleus and tibialis anterior but was reduced from 49% to 36% in the medial gastrocnemius. The maximum rate of shortening of all three muscles was unaffected by suspension. These results indicate that suspension of the hind limbs selectively affects the mass and force-generating capabilities of the plantarflexors, particularly the predominantly slow soleus. In contrast, the fatigability of only the fast plantarflexor was increased whereas the slow plantarflexor was unaffected. These results, considered in light of collaborative studies, suggest that the chronic force-time levels in a muscle have an important influence on tension- and speed-related properties but not necessarily the fatigability of that muscle. Further, a marked difference in the sensitivity of the contractile elements of slow and fast muscle to this influence was evident.

Effects of bromide on the formation of THMs and HAAs

The role of bromide in the formation and speciation of disinfection by-products (DBPs) during chlorination was investigated. The molar ratio of applied chlorine to bromide is an important factor in the formation and speciation of trihalomethanes (THMs) and halogenacetic acids (HAAs). A good relationship exists between the molar fractions of THMs and the bromide incorporation factor. The halogen substitution ability of HOBr and HOCl during the formation of THMs and HAAs can be determined based on probability theory. The formation of HAAs, and their respective concentrations, can also be estimated through use of the developed model.

Hedgehog signaling in germ cell migration

The primitive gonad of the Drosophila embryo is formed from two cell types, the somatic gonad precursor cells (SGPs) and the germ cells, which originate at distant sites. To reach the SGPs the germ cells must undergo a complex series of cell movements. While there is evidence that attractive and repulsive signals guide germ cell migration through the embryo, the molecular identity of these instructive molecules has remained elusive. Here, we present evidence suggesting that hedgehog (hh) may serve as such an attractive guidance cue. Misexpression of hh in the soma induces germ cells to migrate to inappropriate locations. Conversely, cell-autonomous components of the hh pathway appear to be required in the germline for proper germ cell migration.

Catalytic amide formation with alpha'-hydroxyenones as acylating reagents

Alpha'-hydroxyenones undergo clean, catalytic amidations with amines promoted by the combination of an N-heterocyclic carbene and 1,2,4-triazole.

The surface characteristics of activated carbon as affected by ozone and alkaline treatment

The surface chemical characteristics of activated carbon treated by ozone and alkaline are determined in terms of surface functional groups and surface acidity. Surface functional groups are analyzed by the IR spectroscopic method and Boehm's titration technique. The surface acidity of activated carbon is determined by electrophoretic mobility measurements. The oxygen concentration of activated carbon increases upon ozone and NaOH treatment. Surface functional groups increase mostly in the hydroxyl and carboxyl categories rather than the carbonyl category upon ozone and NaOH treatment.

Occurrence and assessment of treatment efficiency of nonylphenol, octylphenol and bisphenol-A in drinking water in Taiwan

Occurrence and methods for the removal of nonylphenolic compounds in drinking water have been gaining increased attention due to their widespread presence in natural water and the potential health risks from the consumptions of drinking water. The purpose of this study was to assess the occurrence of nonylphenol (NP), octylphenol (OP), and bisphenol-A (BPA) in water sources and treated water in Taiwan, to evaluate the treatment efficiencies of these compounds in both the conventional (coagulation, sedimentation, filtration and chlorination) and advanced treatment processes. The treatment efficiencies of these chemicals were assessed based on their concentrations in water sources, and the results were verified with laboratory simulated treatment processes. A survey of NP, OP, and BPA in 11 Taiwanese water sources showed that all of them could be identified in most of the sampled sources, and that higher concentrations of NP were found when the raw water was contaminated by domestic wastewater. However, higher treatment efficiency could be observed when the NP concentration in water source is high. Laboratory simulation studies of conventional treatment processes showed that chlorination played an important role in the degradation of NP in raw water. Treatment efficiencies of 60%-90% were achieved for NP removal when sufficient chlorine dosages were applied to satisfy chlorine demands. However, results also showed that conventional coagulation and rapid filtration processes were less effective in the reduction of phenolic compounds in water.

Cancer beliefs in ethnic minority populations: a review and meta-synthesis of qualitative studies

People from ethnic minorities often experience poorer cancer outcomes, possibly due to later presentation to healthcare and later diagnosis. We aimed to identify common cancer beliefs in minority populations in developed countries, which can affect symptom appraisal and help seeking for symptomatic cancer. Our systematic review found 15 relevant qualitative studies, located in the United Kingdom (six), United States (five), Australia (two) and Canada (two) of African, African-American, Asian, Arabic, Hispanic and Latino minority groups. We conducted a meta-synthesis that found specific emotional reactions to cancer, knowledge and beliefs and interactions with healthcare services as contributing factors in help seeking for a cancer diagnosis. These findings may be useful to inform the development of interventions to facilitate cancer diagnosis in minority populations.

N-Heterocyclic Carbenes as Organic Catalysts

The synthetic utility of azolium salts as catalysts was thought to be limited to the generation of acyl anion equivalents for use in benzoin and Stetter reactions. The discovery, in 2004, of new catalysts, substrates, and reaction manifolds has ignited a new generation of reactions that fall under the general rubrik of N-heterocyclic carbene (NHC) catalyzed reactions. These powerful new processes include the catalytic generation of activated carboxylates for α-functionalized aldehydes, enantioselective annulations via catalytically generated ester enolate equivalents, and the NHC-catalyzed generation of formal homoenolate equivalents. The history of these new reactions and an overview of the reactions, their substrate scope, and mechanistic pathways are summarized in this Chapter.

Modeling VOCs adsorption onto activated carbon

The activated carbon adsorption process is affected by the characteristics of adsorbent, adsorbate and environmental conditions. In this study, both adsorption and desorption processes are assumed to occur simultaneously and a numerical model was developed with a non-linear driving force in conjunction with the Langmuir model for predicting the overall adsorption process. The numerical model provides both adsorption and desorption rate constants and activation energies. The resultant equilibrium constants are of the same order of magnitude as reported by other studies. Results show that the model could well predict the adsorption isotherms and breakthrough curves under various conditions.

Pentoxifylline prevents endothelial damage due to ischemia and reperfusion injury

BACKGROUND

Endothelial injury after ischemia and reperfusion is characterized by an increase in permeability, cellular edema, and loss of acetylcholine-mediated vasorelaxation. Three hours of ischemia followed by 2 hr of reperfusion in the New Zealand white rabbit hindlimb has been shown to result in loss of acetylcholine-induced superficial femoral artery vasorelaxation. The purpose of this study was to evaluate the effect of intraarterial pentoxyfylline (PTX) on this endothelial injury.

METHODS

New Zealand white rabbits underwent 3 hr of complete hindlimb ischemia followed by 2 hr of reperfusion. Twenty milliliters of either 100 microM PTX or normal saline was infused over 20 min via the circumflex iliac artery at initiation of reperfusion. Superficial femoral artery rings were then evaluated in vitro for endothelial cell-mediated relaxation. Rings were exposed to standardized incremental doses of acetylcholine after norepinephrine-induced contraction and percentage relaxation was measured. Sections of arteries were also sent for hematoxylin and eosin staining.

RESULTS

Similar contraction responses following NE stimulation were observed between control and PTX-treated rings. Control rings relaxed a mean of 14.97 +/- 3.64, 23.17 +/- 5.61, and 31.84 +/- 8.43% in response to acetylcholine doses of 6 x 10(-8), 1 x 10(-7), and 1.5 x 10(-7) M, respectively. In contrast, PTX-treated segments relaxed a mean of 47.52 +/- 8.88, 62.32 +/- 6.83, and 76.73 +/- 4.91% to the same doses of acetylcholine. Differences in relaxation between control and PTX-treated vessels were significantly different at each dose (P < 0.05, Student's t test). Histologic examination of the PTX-treated and control arteries revealed an intact endothelium without morphologic differences between the two groups.

CONCLUSION

In this model of rabbit hindlimb ischemia, endothelial cell-mediated vasorelaxation was preserved with the administration of intraarterial PTX during reperfusion compared to controls. The different relaxation responses could not be attributed to altered arterial contractility in response to norepinephrine, or explained by histologic changes in the arterial wall. These studies demonstrate a potential modality for therapeutic intervention to reduce reperfusion injury after acute limb ischemia.

NOM characteristics and treatabilities of ozonation processes

The objectives of this study were intended to evaluate the effects of the characteristics of natural organic matter on the treatabilities of ozonation, coagulation, filtration, and granular activated carbon processes. The ultra-violet absorbance (UV254) was used as a surrogate parameter to assess each process in reducing the disinfection by-product formation potential (DBPFP). The results indicate that the DBPFP varies with the sources of water samples and treatment processes, but is closely related to the measurement of UV254/DOC. Coagulation/sedimentation can eliminate large molecular weight organic fractions. Both pre- and post-ozonation processes can reduce some of DBP precursors than the conventional treatment process, and are more reliable for reducing the overall DBPFP.

Carbofuran-induced delayed neuropathy

BACKGROUND

Although carbamates have been widely used in the world for many years, carbamate-induced delayed neuropathy is rare. We report what appears to be delayed neuropathy caused by poisoning with carbofuran, a cholinesterase-inhibiting carbamate, although the certainty of diagnosis is somewhat limited by the lack of a sural nerve biopsy and spinal fluid examination.

CASE REPORT

A 23-year-old man attempted suicide by ingesting 100 mL of carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate). After recovering from acute cholinergic toxicity, he had notable paresthesia in his lower limbs and difficulty walking. Electrophysiologic findings revealed sensorimotor neuropathy. Recovery began at 1 week and continued for 4 months. A similar delayed neuropathy has been described with carbamate, 1-naphthyl N-methylcarbamate, and m-tolyl methylcarbamate, but not with carbofuran insecticides.

Characteristics of organic precursors and their relationship with disinfection by-products

The molecular weight distribution and chemical composition of precursors and their relationship with disinfection by-products (DBPs) were investigated. Most of the organic matter responsible for the major DBP precursors in the Pan-Hsin water are small compounds with a molecular weight less than 1 kDa. The hydrophobic acids display the greatest ability to produce DBP. Therefore, effective removal of small molecules or hydrophobic acidic organics prior to disinfection process will significantly reduce the DBP concentration in the finished water. Although the coagulation process is effective in removing large organic precursors and the removal efficiencies of CHCl3 formation potential and organic carbon increase proportionally to the molecular weight of the precursors, the conventional treatment methods have limited efficiency in eliminating small precursors, which have high DBP formation potential.

Decomposition of 2-naphthalenesulfonate in aqueous solution by ozonation with UV radiation

This study investigates the ozonation of 2-naphthalenesulfonate (2-NS) combined with ultraviolet (UV) radiation. Naphthalenesulfonic acids are of importance as dye intermediates for the dye and textile auxiliary industries. Its derivatives, such as 2-NS, have been found in rivers and tannery effluents causing pollution problems. Thus, the 2-NS is of concern for the aquatic pollution control especially in the surface and waste waters. Ozonation combined with UV radiation is employed for the removal of 2-NS in the aqueous solution. Semibatch ozonation experiments were proceeded under different reaction conditions to study the effects of ozone dosage and UV radiation on the oxidation of 2-NS. The concentrations of 2-NS and sulfate are analyzed at specified time intervals to elucidate the decomposition of 2-NS. In addition, values of pH and oxidation reduction potential are continuously measured in the course of experiments. Total organic carbon is chosen as a mineralization index of the ozonation of 2-NS. The mineralization of 2-NS via the ozonation is remarkably enhanced by the UV radiation. These results can provide useful information for the proper removal of 2-NS in the aqueous solution by the ozonation with UV radiation.

Comparisons of metal leachability for various wastes by extraction and leaching methods

The objective of this research was to evaluate three extraction tests, i.e., toxicity characteristic leaching procedures (TCLP), extraction procedure (EP), and American Society for Testing and Materials (ASTM) methods, for their ability to extract metals in chemical sludge and incineration bottom ash, in terms of the precision of analytical results. Typical chemical sludges, including the electroplating and dye-stuff sludges, the municipal solid waste incineration bottom ash, the leather debris, and the steel-mill bottom residue containing Cd, Cr, Cu, Pb, and Zn were prepared for the lysimetry test (dynamic testing) to compare with the extraction results. Results show that for bottom residue and dye-stuff sludge, the concentration of metal leached was almost the same between the lysimetry leaching and the TCLP tests. The metal concentration followed the order: TCLP approximately = EP > ASTM. TCLP and EP exhibited almost the same relative standard deviation (RSD) value. Therefore, the results of the TCLP tests for bottom residue and dye-stuff sludge, which have a low metal content and alkalinity, can be used to estimate the metal concentration leached by typical acid rain in Taiwan; whereas the ASTM extraction test may be a better indicator of the lysimetry test.

Oculogyric spasm in Asian psychiatric in-patients on maintenance medication

BACKGROUND

The objective was to investigate the occurrence and characteristics of oculogyric spasm (OGS) in an Asian country.

METHOD

All 2035 Asian (88% Chinese, 7% Malays and 5% Indonesians) psychiatric in-patients in the state psychiatric hospital in Singapore were surveyed for occurrence of oculogyric spasm (OGS) over a two-month period.

RESULTS

Thirty-four patients (1.7%) developed OGS (53% male and 47% female). All the 34 patients had been on maintenance antipsychotic drugs for more than five months. Eighteen patients had recurrent attacks. The mean chlorpromazine equivalent daily dose for those patients with recurrent OGS was 511 mg. This was significantly higher (P < 0.05) than the 277 mg daily dose received by those without recurrent OGS. Most (68%) of the attacks occurred between 1400-2000 h suggesting that OGS may have a diurnal variation.

CONCLUSIONS

OGS presenting as tardive dystonia may be due to a relative increase in cholinergic activity.

Vector-mediated expression of erythropoietin improves functional outcome after cervical spinal cord contusion injury

We evaluated the therapeutic effect of erythropoietin (EPO) delivered by direct injection of a nonreplicating herpes simplex virus (HSV)-based vector coding for EPO (vEPO) in a model of cervical hemicord contusion at C7. At 1 h after spinal cord injury (SCI), either vEPO or control vector carrying a reporter gene (vC) was injected into the cord above and below the lesion. Animals injected with vEPO showed a statistically significant improvement in the ipsilateral forelimb function, as measured by open-field evaluation of motor performance, forelimb reaching in the cylinder test and misplacement in grid walk. This correlated with preservation of gray matter in the area of the lesion. There was also mild but significant improvement of hindlimb motor function measured by Basso-Beattie-Bresnahan score and computerized gait analysis in vEPO compared with control vector-injected animals. Microtubule-associated protein tau, phosphorylated and nonphosphorylated neurofilament protein and the synaptic proteins synaptophysin and PSD-95 were all significantly increased in the spinal cord of vEPO-treated animals compared with control vector-injected animals. These data suggest that gene transfer of EPO after cervical SCI by minimizing the injury size and enhancing tissue sparing preserves large-caliber axons and promotes synaptogenesis.

Effects of polydiallyldimethyl ammonium chloride coagulant on formation of chlorinated by products in drinking water

The objectives of this research work was to evaluate the reduction of THM precursors by cationic p-DADMAC and determine the correlations between the chlorine demand and trihalomethane formation in the presence of electrolyte solutions and ambient light. The chlorine demand was found to be significantly reduced provided that the H2SO4 electrolyte was fed to the sample solutions. The amount of CHCl3 formation was also decreased when the Na2SO4 electrolyte was introduced in spite of the levels of light intensity. The p-DADMAC can not only effectively remove the turbidity but also reduce the formation of CHCl3. The optimum dosage of p-DADMAC for reducing the turbidity, TOC and CHCl3 in the humic acid and source water samples was determined and depended upon the nature of organics.

Decomposition of 2-mercaptothiazoline in aqueous solution by ozonation

This study investigates the ozonation of 2-mercaptothiazoline (2-MT). The 2-MT is one of the important organic additives for the electroplating solution of the printed wiring board industry and has been widely used as a corrosion inhibitor in many industrial processes. It is of concern for the aquatic pollution control especially in the wastewaters. Semibatch ozonation experiments in the completely stirred tank reactor are performed under various concentrations of input ozone. The concentrations of 2-MT, sulfate, and ammonium are analyzed at specified time intervals to elucidate the decomposition of 2-MT during the ozonation. In addition, the time variation of the dissolved ozone concentration (C(ALb)) is continuously monitored in the course of experiments. Total organic carbon (TOC) is chosen and measured as a mineralization index of the ozonation of 2-MT. The results indicate that the decomposition of 2-MT is efficient, while the mineralization of TOC is limited via the ozonation only. Simultaneously, the yield of sulfate with the maximum value of about 47% is characterized by the increases of TOC removal and ozone consumption. These results can provide some useful information for assessing the feasibility of the treatment of 2-MT in the aqueous solution by the ozonation.