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Biomedical subjects

Jun Lin

Publications and source records attributed to Jun Lin.

At least 37 records · Page 2Linked to original sources
PubMed2005

Inclusion complexes of azadirachtin with native and methylated cyclodextrins: solubilization and binding ability.

The inclusion complexation behavior of azadirachtin with several cyclodextrins and their methylated derivatives has been investigated in both solution and the solid state by means of XRD, TG-DTA, DSC, NMR, and UV-vis spectroscopy. The results show that the water solubility of azadirachtin was obviously increased after resulting inclusion complex with cyclodextrins. Typically, beta-cyclodextrin (beta-CD), dimethyl-beta-cyclodextrin (DMbetaCD), permethyl-beta-cyclodextrin (TMbetaCD), and hydroxypropyl-beta-cyclodextrin (HPbetaCD) are found to be able to solubilize azadirachtin to high levels up to 2.7, 1.3, 3.5, and 1.6 mg/mL (calculated as azadirachtin), respectively. This satisfactory water solubility and high thermal stability of the cyclodextrin-azadirachtin complexes, will be potentially useful for their application as herbal medicine or healthcare products.

Cyclodextrins↗
PubMed2005

Study of quasi-monodisperse In2O3 nanocrystals: synthesis and optical determination.

In this communication, we report a successful synthesis of quasi-monodisperse In2O3 nanocrystals with high crystallinity in a high-temperature organic solution. The average size of nanocrystals can be tuned using a dynamic injection technique. TEM and XRD investigations indicate that each nanocrystal is a single crystal. The optical determination implies that the photoluminescence behavior of these In2O3 nanocrystals is different from that of the bulk, probably due to the combination of weak quantum-confinement-effects and the nature of high crystallinity in nanocrystals.

Journal Article↗
PubMed2005

Enhanced in vivo fitness of fluoroquinolone-resistant Campylobacter jejuni in the absence of antibiotic selection pressure.

Campylobacter jejuni, a major foodborne human pathogen, has become increasingly resistant to fluoroquinolone (FQ) antimicrobials. By using clonally related isolates and genetically defined mutants, we determined the fitness of FQ-resistant Campylobacter in chicken (a natural host and a major reservoir for C. jejuni) in the absence of antibiotic selection pressure. When monoinoculated into the host, FQ-resistant and FQ-susceptible Campylobacter displayed similar levels of colonization and persistence in the absence of FQ antimicrobials. The prolonged colonization in chickens did not result in loss of the FQ resistance and the resistance-conferring point mutation (C257 --> T) in the gyrA gene. Strikingly, when coinoculated into chickens, the FQ-resistant Campylobacter isolates outcompeted the majority of the FQ-susceptible strains, indicating that the resistant Campylobacter was biologically fit in the chicken host. The fitness advantage was not due to compensatory mutations in the genes targeted by FQ and was linked directly to the single point mutation in gyrA, which confers on Campylobacter a high-level resistance to FQ antimicrobials. In certain genetic backgrounds, the same point mutation entailed a biological cost on Campylobacter, as evidenced by its inability to compete with the FQ-susceptible Campylobacter. These findings provide a previously undescribed demonstration of the profound effect of a resistance-conferring point mutation in gyrA on the fitness of a major foodborne pathogen in its natural host and suggest that the rapid emergence of FQ-resistant Campylobacter on a worldwide scale may be attributable partly to the enhanced fitness of the FQ-resistant isolates.

Animals↗
PubMed2005

Radioactivity concentrations in soils of the Xiazhuang granite area, China.

The natural radioactivity of soils at the Xiazhuang granite massif of Southern China has been studied. The radioactivities of 55 samples have been measured with a low-background HPGe detector. The radioactivity concentrations of (238)U and (40)K ranged from 40.2 to 442 and from 442 to 913 Bq/kg, respectively, while the radioactivity concentration of (232)Th varied only slightly. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity (Ra(eq)), the absorbed dose rate (D ), the annual effective dose rate and the external hazard index (H(ex)) have been calculated and compared with the internationally approved values. The study provides background radioactivity concentrations in a granite area, specifically, the area in the vicinity of a uranium mine in Southern China. The data can be used in exploring granite-type uranium deposits.

Algorithms↗
PubMed2005

Peritoneal fluid concentrations of interleukin-17 correlate with the severity of endometriosis and infertility of this disorder.

This prospective study aimed to determine whether patients with endometriosis are having different level of interlukin-17 (IL-17) in peritoneal fluid when compared with patients without endometriosis. The patients with minimal/mild endometriosis had a significantly higher level of IL-17 in peritoneal fluid compared with those with moderate/severe endometriosis or without endometriosis. The concentration of IL-17 in peritoneal fluid was significantly higher when endometriosis and infertility coexist. However, the concentration of IL-17 in peritoneal fluid did not correlate with the phase of the menstrual cycle in the patients with or without endometriosis. Our study suggested that IL-17 might play an important role in the pathogenesis of early endometriosis and endometriosis-associated infertility.

Abdominal Pain↗
PubMed2005

CmeR functions as a transcriptional repressor for the multidrug efflux pump CmeABC in Campylobacter jejuni.

CmeABC, a resistance-nodulation-division (RND) type of efflux pump, contributes to Campylobacter resistance to a broad spectrum of antimicrobial agents and is also essential for Campylobacter colonization of the animal intestinal tract by mediation of bile resistance. As one of the main systems for Campylobacter adaptation to different environments, CmeABC is likely subject to control by regulatory elements. We describe the identification of a transcriptional repressor for CmeABC. Insertional mutagenesis of cmeR, an open reading frame immediately upstream of the cmeABC operon, resulted in overexpression of cmeABC, as determined by transcriptional fusion (P(cmeABC-lacZ)) and immunoblotting with CmeABC-specific antibodies. Overexpression of the efflux pump was correlated with a moderate increase in the level of resistance of the cmeR mutant to several antimicrobials. In vitro, recombinant CmeR bound specifically to the promoter region of cmeABC, precisely, to the inverted repeat sequences in the cmeABC promoter. A single nucleotide deletion between the two half sites of the inverted repeat reduced the level of CmeR binding to the promoter sequence and resulted in overexpression of cmeABC. Together, these findings indicate that cmeR encodes a transcriptional repressor that directly interacts with the cmeABC promoter and modulates the expression of cmeABC. Mutation either in CmeR or in the inverted repeat impedes the repression and leads to enhanced production of the MDR efflux pump.

Amino Acid Sequence↗
PubMed2005

Bile salts modulate expression of the CmeABC multidrug efflux pump in Campylobacter jejuni.

CmeABC, a multidrug efflux pump, is involved in the resistance of Campylobacter jejuni to a broad spectrum of antimicrobial agents and is essential for Campylobacter colonization in animal intestine by mediating bile resistance. Previously, we have shown that expression of this efflux pump is under the control of a transcriptional repressor named CmeR. Inactivation of CmeR or mutation in the cmeABC promoter (PcmeABC) region derepresses cmeABC, leading to overexpression of this efflux pump. However, it is unknown if the expression of cmeABC can be conditionally induced by the substrates it extrudes. In this study, we examined the expression of cmeABC in the presence of various antimicrobial compounds. Although the majority of the antimicrobials tested did not affect the expression of cmeABC, bile salts drastically elevated the expression of this efflux operon. The induction was observed with both conjugated and unconjugated bile salts and was in a dose- and time-dependent manner. Experiments using surface plasmon resonance demonstrated that bile salts inhibited the binding of CmeR to PcmeABC, suggesting that bile compounds are inducing ligands of CmeR. The interaction between bile salts and CmeR likely triggers conformational changes in CmeR, resulting in reduced binding affinity of CmeR to PcmeABC. Bile did not affect the transcription of cmeR, indicating that altered expression of cmeR is not a factor in bile-induced overexpression of cmeABC. In addition to the CmeR-dependent induction, some bile salts (e.g., taurocholate) also activated the expression of cmeABC by a CmeR-independent pathway. Consistent with the elevated production of CmeABC, the presence of bile salts in culture media resulted in increased resistance of Campylobacter to multiple antimicrobials. These findings reveal a new mechanism that modulates the expression of cmeABC and further support the notion that bile resistance is a natural function of CmeABC.

Anti-Bacterial Agents↗
PubMed2005

Polyol-mediated synthesis and photoluminescent properties of Ce3+ and/or Tb3+-doped LaPO4 nanoparticles.

Rare-earth ion (Ce3+, Tb3+) doped LaPO4 nanoparticles were prepared by the polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV-vis absorption spectroscopy, photoluminescence (PL) spectroscopy, and lifetimes. The results of XRD indicate that the as-prepared nanoparticles are well-crystallized at 160 degrees C and assigned to the monoclinic monazite structure of the LaPO4 phase. The obtained LaPO4:Ce3+, Tb3+ nanoparticles are spherical with narrow size distribution and average size of 20 nm. The doped rare-earth ions show their characteristic emission in LaPO4 nanoparticles, i.e., Ce3+ 5d-4f and Tb3+ 5D4-7FJ (J = 6-3) transitions, respectively. The optimum doping concentration for Tb3+ in La(0.8-x)Ce0.2TbxPO4 nanoparticles is determined to be 15 mol% (x = 0.15). The luminescence decay curves of Ce3+ in LaPO4:Ce3+ and LaPO4:Ce3+, Tb3+ nanoparticles present a single-exponential behavior, and the lifetimes (tau) of Ce3+ decrease with increasing Tb3+ concentrations (at the constant Ce3+ concentration) in LaPO4:Ce3+, Tb3+ nanoparticles due to the energy transfer from Ce3+ to Tb3+. The energy-transfer efficiency from Ce3+ to Tb3+ was calculated, which depends on the doping concentrations of Tb3+ if the concentration of Ce3+ is fixed.

Cesium↗
PubMed2005

[Determination of interleukine-16 levels in peritoneal fluid and serum of women with endometriosis].

OBJECTIVE: To investigate the role of interleukine-16 (IL-16) in the pathogenesis of endometriosis. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of IL-16 in peritoneal fluid and serum specimens of 22 women with different stage endometriosis and 22 controls. RESULTS: The median levels of IL-16 in peritoneal fluid and serum were 290.5 pg/ml and 539.4 pg/ml in women with endometriosis, and 296.6 pg/ml and 778.1 pg/ml in controls, respectively; there was no significant difference between two groups (P>0.05). However, the IL-16 levels in peritoneal fluid and serum of patients with minimal/mild stage endometriosis and controls were all significantly higher than those of patients with moderate/severe endometriosis (P<0.01, <0.05). In addition, there was no statistical correlation of peritoneal IL-16 levels with those in serum (P>0.05). CONCLUSION: Reduced levels of IL-16 in peritoneal fluid and serum of women with advanced stage endometriosis may imply a role of IL-16 in the development and progression of endometriosis.

Adult↗
PubMed2005

[Effects of Naomaitai capsule on learning and memory and content of Ach in rat model produced by cerebral ischemia-reperfusion].

OBJECTIVE: To observe the effects of Naomaitai capsule on the learning and memory abilities and the content of acetylcholine(Ach) in the brain tissue of the model rat. METHOD: One vascular dementia(VD) model was produced by occlusion of bilateral common carotid arteries in rats with following steps: ischemia 20 minutes-reperfusion 10 minutes-ischemia 20 minutes. The learning and memory abilities were tested by water maze. The other VD model was formed by 4-vessel occlusion-reperfusion injury in rats. The time of right reflect recovery and the content of Ach in the brain tissue were determined. RESULT: Naomaitai capsule can significantly improve the learning and memory abilities of the dementia rats( P < 0.05, P < 0.01), increase the content of Ach (P < 0.05, P < 0.01) and reduce the time of right reflect recovery(P < 0.01). CONCLUSION: Naomaitai capsule can improve the learning and memory abilities by increasing the content of Ach of the VD rats.

Acetylcholine↗
PubMed2005

[Determination of interleukin-17 concentrations in peritoneal fluid of women with endometriosis].

OBJECTIVE: To investigate the role of interleukin-17 (IL-17) in the pathogenesis of endometriosis. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of IL-17 in peritoneal fluid of 36 patients with different stage endometriosis and 26 patients without endometriosis. RESULTS: The concentrations of IL-17 in peritoneal fluid of the patients with and without endometriosis were (5.7 +/- 1.9) ng/L and (5.3 +/- 1.4) ng/L, respectively, without significant difference between the two groups (P > 0.05). According to staging criteria of r-AFS, the concentrations of peritoneal IL-17 in the patients with stage I-II endometriosis (6.4 +/- 1.7) ng/L were significantly higher than those in the patients with stage III-IV endometriosis (5.1 +/- 1.8) ng/L and in the patients without endometriosis (P < 0.05). There was no difference with regard to peritoneal IL-17 concentrations between proliferative and secretory phases in the patients with or without endometriosis (P > 0.05). The levels of peritoneal IL-17 were significantly higher in the endometriosis patients with infertility (6.4 +/- 1.8) ng/L than in the endometriosis patients without infertility (5.1 +/- 1.8) ng/L (P < 0.05). CONCLUSION: IL-17 may play an important role in the pathogenesis of early endometriosis and pathophysiology of endometriosis-associated infertility.

Adult↗
PubMed2004

Formation and photoluminescence of silver nanoparticles stabilized by a two-armed polymer with a crown ether core.

Silver nanoparticles were synthesized by the use of a two-armed polymer with a crown ether core [poly(styrene)]-dibenzo-18-crown-6-[poly(styrene)] based on the flexibility of the polymer chains and the complex effect of crown ether with Ag(+) and Ag. The size of silver nanoparticles could be tailored by controlling the initial concentrations of the polymer and Ag(+), and the molecular weight of the polymer. The emission of silver nanoparticles was blue-shifted, and the intensity of the photoluminescence of silver nanoparticles stabilized by the polymer was significantly increased due to the complex effect between the crown ether embedded in the polymer and the silver nanoparticles.

Journal Article↗
PubMed2004

Shape evolution and self assembly of monodisperse PbTe nanocrystals.

In this communication, we report our recent achievement in synthesis and self-assembly of both spherical and cubic PbTe nanocrystals using a high-temperature solution-phase synthesis approach. The possible mechanism of nanocrystalline evolution from spherical to cubic structure has also been discussed. It is possible to use the highly orientated PbTe nanocrystals as building blocks to achieve thickness-controlled film for further manipulation into thermoelectric devices.

Journal Article↗
PubMed2004

Preparation and photocatalytic behavior of MoS2 and WS2 nanocluster sensitized TiO2.

A new approach has been developed for the fabrication of visible light photocatalysts. Nanoclusters of MoS2 and WS2 are coupled to TiO2 by an in situ photoreduction deposition method taking advantage of the reducing power of the photogenerated electrons from TiO2 particles. The photocatalytic degradation of methylene blue and 4-chlorophenol in aqueous suspension has been employed to evaluate the visible light photocatalytic activity of the powders. The blue shift in the absorption onset confirms the size quantization of MS2 nanoclusters, which act as effective and stable sensitizers, making it possible to utilize visible light in photocatalysis. Quantum size effects alter the energy levels of the conduction and valence band edges in the coupled semiconductor systems, which favors the interparticle electron transfer. In addition, the coupled systems are believed to act in a cooperative manner by increasing the degree of charge carrier separation, which effectively reduces recombination.

Journal Article↗
PubMed2004

The solution structure of rat Abeta-(1-28) and its interaction with zinc ion: insights into the scarcity of amyloid deposition in aged rat brain.

The amyloid beta-peptide (Abeta) is a major component of insoluble amyloid deposits in Alzheimer's disease, and the ability of the beta-peptide to exist in different conformations is dependent on residues 1-28 [beta-(1-28)]. However, different from humans, no Abeta amyloid deposition has been found in aged rats' brains. Studying the three-dimensional solution structure of rat Abeta-(1-28) and the binding circumstance of Zn(2+) is beneficial to a clear understanding of the potential role of Zn(2+) in Alzheimer-associated neuropathogenesis and to suggest why there is no amyloid deposition in aged rats' brains. Here we used nuclear magnetic resonance (NMR) spectroscopy to determine the solution structure of rat Abeta-(1-28) and the binding constant of Zn(2+) to rat Abeta-(1-28). Our results suggest that (1) the three-dimensional solution structure of rat Abeta-(1-28) is more stable than that of human Abeta-(1-28) in DMSO- d(6) and that a helical region from Glu16 to Val24 exists in the rat Abeta-(1-28); (2) the affinity of Zn(2+) for rat Abeta-(1-28) is lower than that for human Abeta-(1-28) and the NMR data suggest that Arg13, His6, and His14 residues provide the primary binding sites for Zn(2+); and (3) the proper binding of Zn(2+) to rat Abeta-(1-28) can induce the peptide to change to a more stable conformation.

Aged↗
PubMed2004

Decreased levels of interleukin-18 in peritoneal fluid but not in serum of patients with endometriosis.

OBJECTIVE: To determine the concentrations of interleukin-18 (IL-18) in peritoneal fluid and serum in patients with endometriosis in comparison with the control group. DESIGN: A prospective analytical study. SETTING: The obstetrics and gynecology department of an academic training hospital. PATIENT(S): Forty-four patients who underwent laparoscopic surgery for benign gynecologic diseases. INTERVENTION(S): Specimens of peripheral blood and peritoneal fluid were obtained before and during laparoscopic procedures, and the levels of IL-18 were analyzed. MAIN OUTCOME MEASURE(S): The concentrations of IL-18 in peritoneal fluid and serum were correlated with the presence of endometriosis, disease stage, and the phase of the menstrual cycle. RESULT(S): Interleukin-18 was detectable in 98% of the peritoneal specimens and 84% of the serum specimens of the patients tested. Peritoneal fluid IL-18 concentrations were statistically significantly lower in patients with endometriosis than in patients without endometriosis; the difference in serum IL-18 levels showed no statistically significant difference between the patients with and without endometriosis. The concentrations of IL-18 in peritoneal fluid and serum were not correlated with the stage of endometriosis or the phase of the menstrual cycle. CONCLUSION(S): Our results suggest that the decreased levels of IL-18 in peritoneal fluid in patients with endometriosis as compared with the control group may play an important role in the pathogenesis of this disease.

Adult↗