Asymmetric 2,4-Dienylation/[4 + 2] Annulation Cascade to Construct Fused Frameworks via Auto-Tandem Palladium Catalysis.

A palladium catalyzed tandem reaction between ortho-functionalized aryl enones and 2,4-dienyl carbonates has been presented, proceeding through sequential 2,4-dienylation/Michael addition/π-σ-π isomerization/allylic alkylation. A broad array of enantioenriched architectures having fused and spirocyclic frameworks are constructed in moderate to excellent yields and stereoselectivity. Notably, the intrinsic intramolecular Diels-Alder reaction pattern of the dienylated intermediates is well reversed via Pd(0)-π-Lewis base catalysis.

Surface-enhanced Raman scattering based determination on sulfamethazine using molecularly imprinted polymers decorated with silver nanoparticles.

Molecularly imprinted polymers (MIPs) were combined with surface-enhanced Raman scattering (SERS) and AgNPs were prepared by in situ reduction within the MIP for selective and sensitive detection of sulfamethazine (SMZ). The MIP@AgNPs composites were characterized in detail by several analytical techniques, showing the generation of polymers and the formation of AgNPs hot spots. The specific affinity and rapid adsorption equilibrium rates of MIP@AgNPs composites were verified by static and kinetic adsorption studies. The MIP@AgNPs with high selectivity and excellent sensitivity were used as SERS substrates to detect SMZ. A good linear correlation (R2 = 0.996) in rang of 10-10-10-6 mol L-1 was observed between the Raman signal (1596 cm-1) and the concentration of SMZ. The limit of detection (LOD) was as low as 8.10 × 10-11 mol L-1 with relative standard deviations (RSD) of 6.32%. The good stability and reproducibility are also fully reflected in the SERS detection based on MIP@AgNPs. The method was successfully applied to the analysis of lake water samples, with recoveries in the range 85.1% to 102.5%. In summary, SERS detection based on MIP@AgNPs can be developed for a wider and broader range of practical applications. Schematic illustration of MIP@AgNPs sensor for the SERS detection of sulfamethazine.

Is there a primitive reflex residue underlying Marcus Gunn Syndrome? Rat electrophysiology.

AIM: To make an electrophysiological demonstration of a possible jaw muscle afferents-oculomotor neural pathway that was proposed by our previous works on rats, which substantiates an early "release hypothesis" on pathogenesis of human Marcus Gunn Syndrome (MGS). METHODS: Extracellular unit discharge recording was applied and both orthodromic and spontaneous unitary firing were recorded in the oculomotor nucleus (III), and the complex of pre-oculomotor interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN), following electric stimulation of the ipsilateral masseter nerve (MN) in rats. RESULTS: Extracellular orthodromic unit discharges, with latencies of 3.7±1.3 and 4.7±2.9ms, were recorded unilaterally in the III, and the INC/DN neurons, respectively. Spontaneous unit discharges were also recorded mostly in the INC/DN and less frequently in the III. Train stimulation could prompt either facilitation or inhibition on those spontaneous unit discharges. The inhibition pattern of train stimulation on the spontaneous discharging was rather different in the III and INC/DN. A slow inhibitory pattern in which spontaneous firing rate decreased further and further following repeated train stimulation was observed in the III. While, some high spontaneous firing rate units, responding promptly to the train stimuli with a short-term inhibition and recovered quickly when stimuli are off, were recorded in the INC/DN. However, orthodromic unit discharge was not recorded in the III and INC/DN in a considerable number of experiment animals. CONCLUSION: A residual neuronal circuit might exist in mammals for the primitive jaw-eyelid reflex observed in amphibians, which might not be well-developed in all experimental mammals in current study. Nonetheless, this pathway can be still considered as a neuroanatomic substrate for development of MGS in some cases among all MGS with different kind of etiology.

Is Marcus Gunn jaw winking a primitive reflex? Rat neuroanatomy.

AIM: To investigate a possible trigeminal proprioceptive-oculomotor neural pathway and explore possible synaptic connections between neurons in this pathway. Attempt to bring a new insight to mechanism of Marcus Gunn syndrome (MGS). METHODS: Anterograde and retrograde tract tracing was applied and combined with immunofluorescent stain in rats. After electrophysiological identifying mesencephalic trigeminal nucleus (Vme) neurons, intracellular injection of tracer was performed to trace axon trajectory. RESULTS: Following injections of anterograde tracers into the Vme, labeled terminals were observed ipsilateral in oculomotor and trochlear nuclei (III/IV), as well as in their premotor neurons in interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN). Combining with choline acetyltransferase (ChAT) immunofluorescent stain, it showed that Vme projecting terminals contact upon ChAT positive III/IV motoneurons under confocal microscope. By retrograde labeling premotor neurons of the III, it showed that Vme neuronal terminals contact with retrogradely labeled pre-oculomotor neurons in the INC/DN. Axons of intracellularly labeled Vme neurons that respond to electric stimuli of the masseter nerve traveled into the ipsilateral III. CONCLUSION: There may exist a trigeminal proprioceptive-oculomotor system neural circuit in the rat, which is probably related to vertical-torsional eye movements. Possible association of this pathway with MGS etiology was discussed.

A microdialysis-based analytical system for dynamic monitoring of arsenic transformation under microbial activity.

In this study, a microdialysis (MD) technique was combined with high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for continuous monitoring of the dynamic variations of arsenic species in a microbe-inoculated culture broth. After optimizing the analytical system, retrodialysis was applied to assess the probe recovery and analytical performance of the proposed method. The mean probe recoveries of four arsenic species were in the range from 57.0 to 81.8%. The limit of detection (LOD) for arsenic was in the range of 0.6-1.8 ng mL-1 and 0.032 µM for MDA, respectively. The accuracy was assessed by an addition/recovery test with a satisfactory value of 98.07-109.08% for arsenic species and 93.57-108.15% for MDA, respectively. To evaluate the practical applicability of this method, we monitored, continuously for 72 h, the dynamic variations of the concentrations of the four arsenic species in a standardized bacterial sample (ATCC 25922). After adding the arsenic species into the bacteria-inoculated broth, we found that the concentration of As3+ decreased over time, whereas As5+ increased in concentration. In addition, malondialdehyde (MDA) was also monitored to evaluate the effect of oxidative damage of the arsenic species on the studied microbial system. Our analyses revealed that the dynamic variations of the arsenic species and MDA could be observed continuously during the microbial growth period. This economical and eco-friendly method might also be helpful for monitoring the transformations of other metal species, oxidation processes, and the bioremediation ability of microbial systems.

Microfluidic desorption-free magnetic solid phase extraction of Hg2+ from biological samples using cysteine-coated gold-magnetite core-shell nanoparticles prior to its quantitation by ICP-MS.

The authors describe a microfluidic method for desorption-free magnetic solid phase extraction (MSPE) of Hg2+ ions prior to their determination through ICP-MS. Nanoparticles comprising a gold core and an iron oxide (Fe3O4) shell were functionalized with l-cysteine and then used to extract trace amounts of Hg2+. In contrast to typical solid phase extraction processes, this approach is rapid and does not require a desorption step. The working pH, amount of adsorbent, sample volume, adsorption selectivity, adsorption capacity, and adsorption flow rate were optimized. Under the optimized conditions, the method was validated through determination of a certified reference material (NIST 1641d; mercury in water); the results were in good agreement. The method was applied to the analysis of (spiked) tap water and gave recoveries ranging from 101.5% to 109.3%. It was also applied to the analysis of biosamples available in limited volumes only, including cerebrospinal fluid and microdialysates.

Oncocytic variant of medullary thyroid carcinoma: 3 cases report with review of literatures / 临床与实验病理学杂志

Purpose To investigate the clinicopathologic features and differential diagnosis of oncocytic variant of medullary thyroid carcinoma (MTC).Methods Morphological,immunohistochemical findings on 3 oncocytic variant of MTC cases and electron microscopic findings on 2 of these 3 cases were studied,with review of the relevant literatures.Results The cytoplasm was abundant,eosinophilic and granular with defined margins.The nuclei were enlarged,round to oval.Prominent nucleoli were identified in some cells.Tumor cells formed sheets,trabeculae or follicles with infiltrative pattern.Immunohistochemically,thyroglobulin (TG) was negative in all 3 cases.Calcitonin was positive in 2 cases and negative in 1 case.Ultrastructurally,a large number of mitochondria and various neuroendocrine granules were found in the 2nd and 3rd cases.Conclusion Oncocytic variant of MTC is very rare with variable histopathologic appearances.It should be considered in diagnosing oncocytic lesions of thyroid.A definite diagnosis can be rendered based on comprehensive findings of the immunohistochemistry,serology study and electron microscopy.It needs to avoid misdiagnosis and missed diagnosis.

Sleep duration, daytime napping, markers of obstructive sleep apnea and stroke in a population of southern China.

Sleep habits are associated with stroke in western populations, but this relation has been rarely investigated in China. Moreover, the differences among stroke subtypes remain unclear. This study aimed to explore the associations of total stroke, including ischemic and hemorrhagic type, with sleep habits of a population in southern China. We performed a case-control study in patients admitted to the hospital with first stroke and community control subjects. A total of 333 patients (n = 223, 67.0%, with ischemic stroke; n = 110, 23.0%, with hemorrhagic stroke) and 547 controls were enrolled in the study. Participants completed a structured questionnaire to identify sleep habits and other stroke risk factors. Least absolute shrinkage and selection operator (Lasso) and multiple logistic regression were performed to identify risk factors of disease. Incidence of stroke, and its subtypes, was significantly associated with snorting/gasping, snoring, sleep duration, and daytime napping. Snorting/gasping was identified as an important risk factor in the Lasso logistic regression model (Lasso' ß = 0.84), and the result was proven to be robust. This study showed the association between stroke and sleep habits in the southern Chinese population and might help in better detecting important sleep-related factors for stroke risk.

Oxidative stress during bacterial growth characterized through microdialysis sampling coupled with HPLC/fluorescence detection of malondialdehyde.

Organisms that grow aerobically are routinely exposed to oxidative stress in the form of reactive oxygen species. Monitoring the dynamic variations of oxidative stress allows us to understand its role in basic cellular function and determine mechanisms of antioxidation. In this study, microdialysis (MD) sampling was employed for continuous monitoring of the formation of malondialdehyde (MDA) in a bacterium-inoculated culture broth. To test the practicality of this approach, oxidative stress was induced by cadmium and then a 60-min interval was selected to collect sufficient amounts of dialysate for high-performance liquid chromatography with fluorescence (HPLC-FL) detection. After optimization of this simple-to-operate, simultaneous, and continuous method for dynamic monitoring of MDA during periods of bacterial growth, a retrodialysis technique and a no-net-flux method were used to assess the probe recovery and analytical performance of the proposed system. The mean probe recovery of MDA was 78.6 ± 0.9%, with intra- and interday precisions of 2.7-6.1 and 3.5-7.6%, respectively. To evaluate the practicality of this method, the dynamic variations in the concentrations of MDA in standardized bacterial species (Staphylococcus aureus, ATCC(®) 29213™) were monitored continuously for 24h. The analytical results confirmed that this MD sampling technique combined with HPLC-FL detection can be used to accurately and continuously monitor the levels of MDA in microbially inoculated culture broths.

Action potential-triggered somatic exocytosis in mesencephalic trigeminal nucleus neurons in rat brain slices.

The neurons in the mesencephalic trigeminal nucleus (MeV) play essential roles in proprioceptive sensation of the face and oral cavity. The somata of MeV neurons are generally assumed to carry out neuronal functions but not to play a direct role in synaptic transmission. Using whole-cell recording and membrane capacitance (C(m)) measurements, we found that the somata of MeV neurons underwent robust exocytosis (C(m) jumps) upon depolarization and with the normal firing of action potentials in brain slices. Both removing [Ca(2+)](o) and buffering [Ca(2+)](i) with BAPTA blocked this exocytosis, indicating that it was completely Ca(2+) dependent. In addition, an electron microscopic study showed synaptic-like vesicles approximated to the plasma membrane in somata. There was a single Ca(2+)-dependent releasable vesicle pool with a peak release rate of 1912 fF s(-1). Importantly, following depolarization-induced somatic exocytosis, GABA-mediated postsynaptic currents were transiently reduced by 31%, suggesting that the somatic vesicular release had a retrograde effect on afferent GABAergic transmission. These results provide strong evidence that the somata of MeV neurons undergo robust somatic secretion and may play a crucial role in bidirectional communication between somata and their synaptic inputs in the central nervous system.

[Relationship between different milk processing and near infrared spectra].

In the present paper, the effects of different milk processing (homogenizing process, pasteurization) on the milk NIR spectra were discussed. It was found that the raw milk and processed milk show significant difference in the 1 890 nm region, which can be used not only to identify the processed milk, but also to offer the basic theory for NIRS in the quality control researches of milk. The absorbance sharply reduced when the liquid milk was treated by a homogenizer, but the absorbance increased after pasteurization. Raw milks absorbance shows a downtrend in the whole region of spectra with increasing pressure. The changes in fat globules structure finally result in absorbance decline. The commercial milk including remade milk was taken for example to discuss the mechanism of detection. The discriminate analysis calibration was developed by SIMCA method and the accuracy of detection is 98.1% for identifying the reconstituted milk in pasteurized milk between 1 800 and 2 200 nm with the pretreatment method of second derivatived and Norris 5.5.

[Study on component detection of cheese wrapped by polyethylene film based on NIRS].

The possibility of direct determination of fat and protein of wrapped cheese by near infrared spectroscopy was studied. The influences of polyethylene film on the spectra were discussed in order to detect the components of wrapped cheese. And the influences were eliminated using Norris derivation filter pretreatment means. The models for fat and protein of wrapped cheese were calibrated by partial least squares regression (PLS) following eliminating outline, spectral pretreatment, and PLS factors optimization. The best models gave standard errors for calibration of 0.240 and 0.355, standard errors for prediction of 0.326 and 0.219, and correlation coefficients of 0.928 and 0.952 for fat and protein of wrapped cheese, respectively. The results showed no difference from those by non-wrapped cheese's models, and were better than wrapped cheese's models without Norris derivation filter pretreatment. Based on the results, it was concluded that near infrared spectroscopy is a reliable, accurate and fast method for non-invasive measurement of wrapped cheese fat and protein.

[Identification of reconstructed milk in raw milk using near infrared spectroscopy].

Feasibility of reconstituted-milk identification in raw milk was investigated using near infrared spectroscopy. And the applicability of MSC for reconstituted-milk identification was discussed. The discrimination analysis calibration was developed by SIMCA method, and the result indicated that the accuracy of detection is 100%, when the content of reconstructed Milk is above 20%, while for the 10% reconstituted milk, the accuracy of detection is 96.7%; On the other hand, the quantity models of reconstituted milk were calibrated by partial least squares regression (r = 0.971, RMSECV = 7.76%, RPD = 5.13), and there were no significant differences between actual value and reconstituted milk prediction value by t test (p = 0.01). All of these suggested that NIRS has good potential to detect adulteration of raw milk with reconstituted milk.

[Inorganic nitrogen and phosphate and potential eutrophication assessment in Liaodong bay].

On basis of field data measured during 4 cruises from June to September in 2002, variation feature of inorganic nitrogen and phosphate in Liaodong Bay was analyzed. Regression analyses of NH4+(-)N, NO3-(-)N, NO2-(-)N and PO4(3-)-P versus pH as well as inorganic nitrogen and phosphate versus salinity were also conducted. Finally, potential eutrophication of Liaodong Bay was assessed. It is shown that inorganic nitrogen and phosphate in Liaodong Bay vary with different months and different locations. In coast areas inorganic nitrogen and phosphate are mainly affected by rivers, while in central areas of the bay, they are subject to marine biochemical process. Ratio of inorganic nitrogen to phosphate rises to 60.6 from 52.5 in early June, then drops to 39, all far above Redfield value 16. Inorganic nitrogen and phosphate versus pH as well as salinity show different correlation. For example, the correlation coefficient of NO2(-)-N and pH even reaches 0.93. During 4 cruises in Liaodong Bay the total inorganic nitrogen is 212.0 microg/L, phosphate 10.1 microg/L, N/P 50.77. Potential eutrophication assessment indicates that during the survey period Liaodong Bay can be classified as a phosphate-limiting moderate-level nutrient area.