Publications by authors named "Luk H"

"Cardiac and respiratory oscillations have been shown to interact with each other. This interaction could reflect autonomic nervous system functionality. Propofol-induced yawning during anesthesia induction seems to be associated with sympathetic activation.

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The excited-state behavior of 9-hydroxy-10-methyl-9-phenyl-9,10-dihydroacridine and its derivative, 9-methoxy-10-methyl-9-phenyl-9,10-dihydroacridine (AcrOR, R = H, Me), was studied via femtosecond and nanosecond UV-vis transient absorption spectroscopy. The solvent effects on C-O bond cleavage were clearly identified: a fast heterolytic cleavage (τ = 108 ps) was observed in protic solvents, while intersystem crossing was observed in aprotic solvents. Fast heterolysis generates 10-methyl-9-phenylacridinium (Acr(+)) and (-)OH, which have a long recombination lifetime (no signal decay was observed within 100 μs).

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Background: Both continuous and intermittent aspiration of subglottic secretions by means of specially designed endotracheal tubes containing a separate dorsal lumen that opens into the subglottic region have been shown to be useful in reducing ventilator-associated pneumonia (VAP). However, the high cost of these tubes restricts their use.

Objective: The aim of this pilot randomized controlled trial was to test the effect of a low-cost device (saliva ejector) for continuous oral suctioning (COS) on the incidence of VAP in patients receiving mechanical ventilation.

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The photochemistry of 4-methoxycarbonylphenyl azide (2a), 2-methoxycarbonylphenyl azide (3a), and 2-methoxy-6-methoxycarbonylphenyl azide (4a) were studied by ultrafast time-resolved infrared (IR) and UV-vis spectroscopies in solution. Singlet nitrenes and ketenimines were observed and characterized for all three azides. Isoxazole species 3g and 4g are generated after photolysis of 3a and 4a, respectively, in acetonitrile.

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Introduction: Women with HER2(+) or triple negative/basal-like (TN/BL) breast cancers succumb to their cancer rapidly due, in part to acquired Herceptin resistance and lack of TN/BL-targeted therapies. BRCA1-IRIS is a recently discovered, 1399 residue, BRCA1 locus alternative product, which while sharing 1365 residues with the full-length product of this tumor suppressor gene, BRCA1/p220, it has oncoprotein-like properties. Here, we examine whether BRCA1-IRIS is a valuable treatment target for HER2(+) and/or TN/BL tumors.

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The photochemistry of 2-naphthylsulfonyl azide (2-NpSO(2)N(3)) was studied by femtosecond time-resolved infrared (TR-IR) spectroscopy and with quantum chemical calculations. Photolysis of 2-NpSO(2)N(3) with 330 nm light promotes 2-NpSO(2)N(3) to its S(1) state. The S(1) excited state has a prominent azide vibrational band.

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An unstable expansion of the polyglutamine repeat within exon 1 of the protein Htt (huntingtin) causes HD (Huntington's disease). Mounting evidence shows that accumulation of N-terminal mutant Htt fragments is the source of disruption of normal cellular processes which ultimately leads to neuronal cell death. Understanding the degradation mechanism of mutant Htt and improving its clearance has emerged as a new direction in developing therapeutic approaches to treat HD.

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Although mouth guards were originally designed for injury prevention, even elite athletes are now using performance mouth guards to improve athletic success. Both expensive custom models and over-the-counter models are available, but the efficacy is not well known. Some athletes remain wary of the perceived potential for detriments using a mouth guard to their performance.

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Previous research has shown reduced tissue disruption and inflammatory responses in women as compared to men following acute strenuous exercise. While the mechanism of this action is not known, estrogen may reduce the inflammatory response through its interaction with granulocytes. The purpose of this study was to determine if estrogen receptor β expression on granulocytes is related to sex differences in tissue disruption in response to an acute heavy resistance exercise protocol.

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We report a series of four patients with macrocephaly-capillary malformation (M-CM) who are the first ever reported M-CM patients among Chinese individuals. The salient clinical features and recent diagnostic criteria are discussed. M-CM is a multisystem disease characterized by macrocephaly and cutaneous vascular malformation.

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Aneuploidy plays an important role in the development of cancer. Here, we uncovered an oncogenic role for geminin in mitotic cells. In addition to chromatin, tyrosine phosphorylated geminin also localizes to centrosome, spindle, cleavage furrow and midbody during mitosis.

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Background: While exercise acts to combat inflammation and aging, the ability to exercise may itself be compromised by inflammation and inflammation's impact on muscle recovery and joint inflammation. A number of nutritional supplements have been shown to reduce inflammation and improve recovery. The purpose of the current investigation was to examine the effect of a multi-nutrient supplement containing branched chain amino acids, taurine, anti-inflammatory plant extracts, and B vitamins on inflammatory status, endothelial function, physical function, and mood in middle-aged individuals.

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Fast response electrochemical impedance (EI) method was developed to detect concentrations of local anesthetic Levobupivacaine. It revealed the EI method possessed fast response and recovery times and the lowest detected concentration was 1 ppm. Pyrrole was electrochemically polymerized to polypyrrole and made a composite with single walled carbon nanotubes coated over gold electrodes for sensing studies.

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The aim of this study was to compare the static and kinetic frictional forces generated by various contemporary designs of self-ligating brackets (SLBs) and different wire alloys. In total, six different brackets (four passive type SLB, one active SLB, and one conventional bracket) were investigated using stainless steel, nickel-titanium, and titanium-molybdenum alloy archwires of several sizes. The friction forces were measured by sliding on a bracket-wire combination system in an EZ instron testing machine.

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The purpose of this study was to verify the concurrent validity of a bar-mounted Myotest® instrument in measuring the force and power production in the squat and bench press exercises when compared to the gold standard of a computerized linear transducer and force platform system. Fifty-four men (bench press: 39-171 kg; squat: 75-221 kg) and 43 women (bench press: 18-80 kg; squat: 30-115 kg) (age range 18-30 years) performed a 1 repetition maximum (1RM) strength test in bench press and squat exercises. Power testing consisted of the jump squat and the bench throw at 30% of each subject's 1RM.

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A time-resolved resonance Raman (TR(3)) and computational investigation of the photochemistry of 4-acetamidophenyl azide and 4-N-methylacetamidophenyl azide in acetonitrile is presented. Photolysis of 4-acetamidophenyl azide appears to initially produce singlet 4-acetamidophenylnitrene which undergoes fast intersystem crossing (ISC) to form triplet 4-acetamidophenylnitrene. The latter species formally produces 4,4'-bisacetamidoazobenzene.

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The photochemistry of 2-naphthoyl azide was studied in various solvents by femtosecond time-resolved transient absorption spectroscopy with IR and UV-vis detection. The experimental findings were interpreted with the aid of computational studies. Using polar and nonpolar solvents, the formation and decay of the first singlet excited state (S(1)) was observed by both time-resolved techniques.

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Carboethoxycarbene reacts with methanol-OD to form an ylide. The formation and decay of this ylide was monitored by ultrafast time-resolved IR spectroscopy. The formation and decay of the ylide is linearly dependent on the concentration of methanol-OD in acetonitrile with second-order rate constants of ylide formation (8.

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Flavonoids are the active components of Herba epimedii (HEP), a commonly used herb for the management of osteoporosis in China over the centuries. The present study aims to characterise the in vivo effects of its total flavonoid (TF) fraction on bone properties and mineral metabolism as well as to study the mechanism involved in achieving its protective effects against ovariectomy (OVX)-induced bone loss. TF suppressed OVX-induced increase in urinary Ca excretion as well as loss of bone mass and strength at the distal femur in mice in a dose-dependent manner.

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Near-infrared Raman spectroscopy is a powerful analytical tool for detecting critical differences in biological samples with minimum interference in the Raman spectra from the native fluorescence of the samples. The technique is often suggested as a potential screening tool for cancer. In this article we report in vitro Raman spectra of squamous cells in normal and cancerous cervical human tissue from seven patients, which have good signal-to-noise ratio and which were found to be reproducible.

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A Clark-type oxygen chip consisting of a polydimethylsiloxane (PDMS) reservoir containing an amino group-modified PDMS oxygen-permeable membrane (OPM) and a glass substrate containing a three-electrode detector has been constructed by using microfabrication techniques, and it is utilized for in situ measurement of the respiration activity of adhering cells. Use of the alginate sol electrolyte and the electroplating Ag/AgCl pseudo-reference electrode can effectively diminish the crosstalk between the electrochemical electrodes and supply a stable potential for the detection of dissolved oxygen, respectively. The Clark-type oxygen chips possess only 1.

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Background: Recent evidence indicates that spontaneous sarcoplasmic reticulum (SR) calcium (Ca) release underlies the mechanism of sinoatrial node (SAN) acceleration during beta-stimulation, indicating the importance of the Ca clock in SAN automaticity. Whether or not the same mechanism applies to atrial ectopic pacemakers (AEPs) remains unclear.

Objective: The purpose of this study was to assess the mechanism of AEP.

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Hemophagocytic syndrome is an uncommon disease characterized by cytokine dysfunction and uncontrolled hemophagocytosis. It arises rarely during pregnancy, in which case maternal and fetal mortality are relatively high. It has some similarities with HELLP syndrome.

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Background: Low-dose aspirin is widely used for prevention of stroke, heart attacks, and death in patients with atherothrombotic disease, but its use is associated with serious gastrointestinal (GI) adverse effects. Gastroprotective drugs (GPDs) have been used to reduce aspirin-related GI complications but are usually underutilized. The aim of this study was therefore to determine the prescription pattern of GPDs with low-dose aspirin therapy.

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