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Biomedical subjects

Q Lu

Publications and source records attributed to Q Lu.

At least 19 recordsLinked to original sources
PubMed2026

[Intestinal microbiota alterations after digestive tract reconstruction surgery and their impacts on host physiology].

The gut microbiota, acknowledged as the human body's 'second genome', plays a pivotal role in maintaining health. Digestive tract reconstruction surgery profoundly alters the anatomical structure and physiological environment of the gastrointestinal tract, thereby inducing significant shifts in the intestinal microbiota. These microbial changes subsequently influence host physiological functions through metabolic, immune, neuroendocrine, and other pathways. For instance, Roux-en-Y gastric bypass surgery enriches short-chain fatty acid(SCFA)-producing Bacteroides, improving systemic insulin sensitivity. Conversely, pancreaticoduodenectomy leads to a marked enrichment of potential pathobionts such as Klebsiella and Clostridium, which may elevate the risk of infections and tumor recurrence. This review comprehensively summarizes the characteristic changes in the gut microbiota following various digestive tract reconstruction procedures and discusses their multifaceted impacts on host physiology, aiming to provide insights for future experimental research and clinical practice.

Humans↗
PubMed2001

Different classifications of UPOs in the parametrically different chaotic ISI series of a neural pacemaker.

Various interspike intervals (ISIs) in a series of spontaneous discharges of experimental neural pacemakers were identified as chaotic and as lying between stable period 2 and stable period 3. The method of So et al. for detection of unstable periodic orbits (UPOs) was applied to analyze two chaotic ISI series generated under the action of [Ca2+]o in different concentrations. In the chaotic ISI series near the stable period 2, an unstable period 2 orbit was detected. In the chaotic ISI series near the stable period 3, both an unstable period 2 orbit and an unstable period 3 orbit were detected. The location of the unstable period 2 orbit was close to that of the stable period 2 in the return map, while the location of the unstable period 3 orbit was close to that of the stable period 3. The results not only revealed the structures of various chaotic ISI series, but also indicated that the classification of UPOs could reflect the experimental control parameters at which the chaotic ISI series were generated. The previously discovered period adding bifurcation in the ISI series generated by experimental neural pacemakers [12] was further described in terms of the evolution of the period orbits.

Action Potentials↗
PubMed2001

Homeostatic regulation of the immune system by receptor tyrosine kinases of the Tyro 3 family.

Receptor tyrosine kinases and their ligands mediate cell-cell communication and interaction in many organ systems, but have not been known to act in this capacity in the mature immune system. We now provide genetic evidence that three closely related receptor tyrosine kinases, Tyro 3, Axl, and Mer, play an essential immunoregulatory role. Mutant mice that lack these receptors develop a severe lymphoproliferative disorder accompanied by broad-spectrum autoimmunity. These phenotypes are cell nonautonomous with respect to lymphocytes and result from the hyperactivation of antigen-presenting cells in which the three receptors are normally expressed.

Animals↗
PubMed2001

Ephrin-B reverse signaling is mediated by a novel PDZ-RGS protein and selectively inhibits G protein-coupled chemoattraction.

Transmembrane B ephrins and their Eph receptors signal bidirectionally. However, neither the cell biological effects nor signal transduction mechanisms of the reverse signal are well understood. We describe a cytoplasmic protein, PDZ-RGS3, which binds B ephrins through a PDZ domain, and has a regulator of heterotrimeric G protein signaling (RGS) domain. PDZ-RGS3 can mediate signaling from the ephrin-B cytoplasmic tail. SDF-1, a chemokine with a G protein-coupled receptor, or BDNF, act as chemoattractants for cerebellar granule cells, with SDF-1 action being selectively inhibited by soluble EphB receptor. This study reveals a pathway that links reverse signaling to cellular guidance, uncovers a novel mode of control for G proteins, and demonstrates a mechanism for selective regulation of responsiveness to neuronal guidance cues.

Animals↗
PubMed2001

N-acetylcysteine improves microcirculatory flow during smoking: new effects of an old drug with possible benefits for smokers.

BACKGROUND: Cigarette smoking provokes marked acute changes in the microcirculatory vasculature, including a reduced blood flow velocity. In accordance with the hypothesis that the reduced blood flow is due to an imbalance between pro-oxidants and oxidants, we recently showed that most of the reduction could be reversed by a high dose of vitamin C. HYPOTHESIS: In the present work we tested the hypothesis that N-acetylcysteine, a mucolyticum and an antioxidant, may have an effect on the smoking-induced changes observed by vital capillary microscopy of the nailfold. METHODS: In all, 37 healthy volunteers of both genders and with varied smoking habits were treated with N-acetylcysteine 200 mg t.i.d. for 2 weeks. In vivo investigation of the microcirculation by capillaroscopy was performed before and after treatment. RESULTS: Treatment with N-acetylcysteine significantly reduced the smoking-induced relative decrease in capillary blood flow velocity in a group of volunteers with varied smoking habits (p = 0.0016). The preventive effect was clearly significant in smokers (p = 0.003). CONCLUSION: Treatment with N-acetylcysteine has a positive impact on microcirculatory flow during smoking, particularly in habitual smokers.

Acetylcysteine↗
PubMed2001

Microchip separations of transition metal ions via LED absorbance detection of their PAR complexes.

Micellar electrokinetic chromatography was utilized in the electrophoretic separation of seven transition metal ions, colorimetrically complexed by 4-(2-pyridylazo)resorcinol (PAR) on a glass capillary electrophoresis microchip. Detection of the PAR metal chelates was demonstrated using a green light emitting diode (540 nm) and a miniature photomultiplier tube. Parameters investigated included the effect of buffer type, pH and surfactant concentration (sodium dodecyl sulfate, SDS) on the separation efficiency. The optimally determined background electrolyte contained 10 mM ammonium phosphate buffer (pH 7.5), 1 mM PAR to prevent kinetic lability problems and 75 mM SDS for enhanced resolution. The separation of seven transition metal ions, Co2+, V3+, Ni2+, Cu2+, Fe2+, Mn2+ and Cd2+, was achievable in under 65 s, with the resolution of each metal ion in excess of 1.60. Detection limits obtained ranged from 400 ppb for Ni2+ to 1.2 ppm for Mn2+.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2001

Biological and genetic characteristics of two Trichinella isolates in China; comparison with European species.

The most recent taxonomic revision in Trichinella genus included 10 taxa. Trichinella spiralis (Ts) is a thoroughly studied species but most of the isolates came from the Europe or American continents. Few information is available from China about the Trichinella isolates and their diversity. In this report two Chinese isolates were characterized and compared with European strains. The in vitro release of newborn larvae (NBL) was determined for the two species. NBL is observed in supernatant of cell culture after adults purification on day 4 post infection (pi) with Ts, and on day 5 pi with Trichinella nativa (Tna). A new parameter was thus proposed to characterize Trichinella strains. Restriction fragment length polymorphism (RFLP) of genomic DNA and random amplified polymorphic cDNA (RAPD) were used to define genetic variability among different isolates. Species specific pattern could be obtained with RAPD but it was far more difficult to get geographical markers for Trichinella using these methods. A low genetic variability in Trichinella species (i.e. a strong "clonality") is suggested.

Animals↗
PubMed2001

A time course study of the protective effect of mesenteric lymph duct ligation on hemorrhagic shock-induced pulmonary injury and the toxic effects of lymph from shocked rats on endothelial cell monolayer permeability.

BACKGROUND: We have previously documented that lymphatic duct division protects against shock-induced lung injury when tested 3 hours post-shock and that lymph collected at 3 hours post-shock increases endothelial cell monolayer permeability. However, whether lymph collected at other time points post-shock also increases endothelial cell permeability is not known. We tested the protective effects of lymphatic division on lung permeability at 6, 12, and 24 hours post-shock and the ability of lymph collected before, during, and hourly (up to 6 hours) after shock to increase endothelial cell monolayer permeability. METHODS: At 3, 6, 12, or 24 hours after sham or actual shock (30 mm Hg for 90 min), lung permeability was measured by using Evans blue dye in rats subjected to sham or actual mesenteric duct ligation. In separate experiments, the ability of lymph collected from rats subjected to shock or sham shock to increase human umbilical vein endothelial cell (HUVEC) monolayer permeability to a 40 kd dextran rhodamine permeability probe. Lymph was tested at 10% and 1% concentrations. RESULTS: Hemorrhagic shock induced a 3- to 4-fold increase in lung permeability compared with sham-shock rats when tested at 3, 6, 12, or 24 hours post-shock. Lymphatic division prevented this increase in lung permeability at each of these time points. Sham shock lymph did not increase HUVEC permeability, while lymph from the shocked rats did, whether tested at 1% or 10%. Lymph samples collected during the shock period and hourly for 6 hours post-shock all increased HUVEC permeability; however, the greatest relative increase in HUVEC permeability was observed in the 3- and 6- hour post-shock samples. CONCLUSIONS: Lung injury after hemorrhagic shock appears to be caused by toxic factors carried in the mesenteric lymph, and factors capable of increasing HUVEC permeability initially appear in the lymph during the shock period and increase over time.

Animals↗
PubMed2001

Factors larger than 100 kd in post-hemorrhagic shock mesenteric lymph are toxic for endothelial cells.

BACKGROUND: Post-shock mesenteric lymph kills and injures endothelial cells (ECs), but neither the mechanism nor the mediators of lymph's toxic effect are known. Thus, in these studies we investigated and characterized potential factors that may be involved in lymph's toxic effect on ECs. METHODS: Lymph was collected hourly from rats before shock, during the shock period, and for 6 hours post-shock and processed in several ways-including removal of cellular elements, freezing, heating, or separation by molecular weight-after which they were tested for toxicity (lactate dehydrogenase as a marker of cell injury and trypan blue as a marker of cell viability). RESULTS: Controls consisting of medium, pre-shock lymph, and post-shock portal vein plasma had no EC toxicity. Lymph collected 1 to 3 hours post-shock resulted in the death of 90% to 95% of ECs and caused an 8- to 10-fold increase in lactate dehydrogenase release; however, this toxic effect waned by 4 hours post-shock. Endotoxin neutralization and immune cell removal did not decrease lymph cytotoxicity but complement inactivation did. By fractionating the toxic lymph samples by size, it appears that the putative EC cytotoxic mediator(s) is larger than 100,000 d. CONCLUSIONS: Mesenteric lymph collected 1 to 3 hours after hemorrhagic shock is toxic to ECs, but this effect is lost by 4- to 5-hours post-shock and is not dependent on the presence of immune cells or endotoxin but does involve complement and other putative mediators of greater than 100,000 d.

Cell Death↗
PubMed2001

Characterization of photosynthetic pigment composition, photosystem II photochemistry and thermal energy dissipation during leaf senescence of wheat plants grown in the field.

Photosynthetic pigment composition and photosystem II (PSII) photochemistry were characterized during the flag leaf senescence of wheat plants grown in the field. During leaf senescence, neoxanthin and beta-carotene decreased concomitantly with chlorophyll, whereas lutein and xanthophyll cycle pigments were less affected, leading to increases in lutein/chlorophyll and xanthophyll cycle pigments/chlorophyll ratios. The chlorophyll a/b ratio also increased. With the progression of senescence, the maximal efficiency of PSII photochemistry decreased only slightly in the early morning (low light conditions), but substantially at midday (high light conditions). Actual PSII efficiency, photochemical quenching and the efficiency of excitation capture by open PSII centres decreased significantly both early in the morning and at midday and such decreases were much greater at midday than in the early morning. At the same time, non-photochemical quenching, zeaxanthin and antheraxanthin contents at the expense of violaxanthin increased both early in the morning and at midday, with a greater increase at midday. The results in the present study suggest that a down-regulation of PSII occurred in senescent leaves and that the xanthophyll cycle plays a role in the protection of PSII from photoinhibitory damage in senescent leaves by dissipating excess excitation energy, particularly when exposed to high light.

Cellular Senescence↗
PubMed2001

Phosphorylation of mitogen-activated protein kinase is regulated by protein kinase C, cyclic 3',5'-adenosine monophosphate, and protein phosphatase modulators during meiosis resumption in rat oocytes.

Mitogen-activated protein (MAP) kinase, protein kinase C (PKC), cAMP, and okadaic acid (OA)-sensitive protein phosphatases (PPs) have been suggested to be involved in oocyte meiotic resumption. However, whether these protein kinases and phosphatases act by independent pathways or interact with each other in regulating meiosis resumption is unknown. In the present study, we aimed to determine the regulation of meiosis resumption and MAP kinase phosphorylation by PKC, cAMP, and OA-sensitive PPs in rat oocytes using an in vitro oocyte maturation system and Western blot analysis. We found that ERK1 and ERK2 isoforms of MAP kinases existed in a dephosphorylated (inactive) form in germinal vesicle breakdown (GVBD)-incompetent and GVBD-competent germinal vesicle intact (GVI) oocytes as well as GVBD oocytes at equivalent levels. These results indicate that MAP kinases are not responsible for the initiation of normal meiotic resumption in rat oocytes. However, when GVBD-incompetent and GVBD-competent oocytes were incubated in vitro for 5 h, MAP kinases were phosphorylated (activated) in GVBD-competent oocytes, but not in meiotic-incompetent oocytes, suggesting that oocytes acquire the ability to phosphorylate MAP kinase during acquisition of meiotic competence. We also found that both meiosis resumption and MAP kinase phosphorylation were inhibited by PKC activation or cAMP elevation. Moreover, these inhibitory effects were overcome by OA, which inhibited PP1/PP2A activities. These results suggest that both cAMP elevation and PKC activation inhibit meiosis resumption and MAP kinase phosphorylation at a step prior to OA-sensitive protein phosphatases. In addition, inhibitory effects of cAMP elevation on meiotic resumption and MAP kinase phosphorylation were not reversed by calphostin C-induced PKC inactivation, indicating that cAMP inhibits both meiotic resumption and MAP kinase activation in a PKC-independent manner.

Animals↗
PubMed2001

Hemorrhagic shock induced up-regulation of P-selectin expression is mediated by factors in mesenteric lymph and blunted by mesenteric lymph duct interruption.

BACKGROUND: Previous studies have shown that mesenteric lymph duct interruption prevents lung injury and decreases lung neutrophil sequestration after hemorrhagic shock (HS). Since endothelial cells rapidly express P-selectin after ischemia/reperfusion injury and HS-induced lung injury appears to involve neutrophil-endothelial cell interactions, we tested the following two hypotheses. First, that HS increases endothelial cell P-selectin expression and that interruption of mesenteric lymph flow in vivo would diminish this expression. Second, that incubation of human umbilical vein endothelial cells with post-HS mesenteric lymph but not sham shock (SS) lymph or postshock portal vein plasma would up-regulate P-selectin expression. METHODS: Pulmonary microvascular P-selectin expression was measured in male rats subjected to 90 minutes of HS (30 mm Hg), SS, or HS with lymphatic ligation, with a dual radiolabeled monoclonal antibody technique. The lungs from these animals were subsequently harvested and P-selectin expression was expressed as mean +/- SEM nanograms of monoclonal antibody per gram of tissue. RESULTS: Pulmonary P-selectin expression was 2.0 +/- 0.4 after SS, 9.7 +/- 3.0 after HS, but decreased to 2.3 +/- 0.3 after HS with lymph interruption (p < 0.05 HS vs. SS or HS plus lymph ligation). Incubation of human umbilical vein endothelial cells with shock lymph collected 3 to 4 hours after shock resulted in a nearly fivefold increase in P-selectin expression (p < 0.001) as compared with SS lymph, lymph collected 6 hours after shock, or postshock portal vein plasma. CONCLUSION: These results support the concept that gut-derived lymph promotes HS-induced lung injury through up-regulation of microvascular adhesion molecules and that intestinal lymph duct interruption may prevent distant organ injury by blunting the expression of these molecules.

Animals↗
PubMed2001

Mesenteric lymph from rats subjected to trauma-hemorrhagic shock are injurious to rat pulmonary microvascular endothelial cells as well as human umbilical vein endothelial cells.

Previously, we have documented that gut-derived lymph from rats subjected to trauma/hemorrhagic shock (T/HS) is injurious to human umbilical vein endothelial cells (HUVEC). To verify these findings in an all rat systems, the ability of T/HS lymph to increase rat pulmonary microvascular endothelial cell (RPMVEC) monolayer permeability and kill RPMVEC was compared with that observed with HUVECs. RPMVEcs isolated from male rats or HUVECs were grown in 24-well plates for the cytotoxicity assays or on permeable filters in a two-chamber system for permeability assays. Mesenteric lymph was collected from male rats subjected to trauma (laparotomy) plus hemorrhagic shock (T/HS group) or to a laparotomy plus sham-shock (T/SS group). The T/HS group had their mean arterial pressure decreased to 30 mmHg and kept there for 90 min. Lymph samples centrifuged to remove the cellular component were incubated with the RPMVECs or HUVECs at a 10% concentration. Neither T/SS lymph nor post-T/HS portal vein plasma was toxic to or increased the permeability of the RPMVECs or HUVECs. The pattern of cytotoxicity observed in the HUVECs incubated with T/HS mesenteric lymph was similar to that observed in the RPMVECs, as reflected by trypan blue dye exclusion, with more than 95% of the HUVECs and RPMVECs being killed after a 16-h incubation with T/HS mesenteric lymph. However, at earlier time points the amount of LDH released from the HUVEC cells incubated with T/HS lymph was greater than that observed with the PRMVEC, although trypan blue dye exclusion was similar. Similarly, incubation with 10% T/HS lymph increased the permeability of both HUVEC and RPMVEC monolayers more than 2-fold, even with an incubation period as short as 1 h. In conclusion, these results provide further evidence that T/HS lymph, but not T/SS lymph or post-T/HS portal vein plasma, is injurious to endothelial cells and that RPMVECs are as susceptible to injury as HUVECs. Additionally, these studies support the emerging concept that gut-induced distant organ injury is mediated by factors contained in mesenteric lymph.

Animals↗
PubMed2001

Galactosyltransferase function during mammalian fertilization.

Gamete recognition has been studied extensively in the mouse. In this system, it is generally believed that sperm bind to a class of O-linked oligosaccharides on the zona pellucida glycoprotein, ZP3. The best characterized sperm receptor for ZP3 is beta1, 4-galactosyltransferase (GalT), which functions in a lectin-like capacity by binding to N-terminal N-acetylglucosamine residues on ZP3 oligosaccharides. Multivalent oligosaccharides on ZP3, as well as synthetic polymers terminating in N-acetylglucosamine aggregate GalT, leading to activation of a heterotrimeric G protein cascade and culminating in the acrosome reaction. Following fertilization, cortical granules release N-acetylglucosaminidase, which removes the binding site for sperm GalT and facilitates the zona block to polyspermic binding. Genetic manipulation of GalT expression has confirmed its function as a ZP3 receptor. Overexpressing GalT on sperm leads to increased binding of ZP3, increased G protein activation, and precocious acrosome reactions. In contrast, sperm from mice made null for GalT by homologous recombination are refractory to ZP3, in that they are unable to bind soluble ZP3 and fail to undergo the acrosome reaction in response to zona glycoproteins. Surprisingly, GalT null sperm still bind to the zona and achieve low rates of fertilization in vitro. This then suggests that sperm-egg binding involves receptor-ligand interactions independent of GalT and ZP3. The current model suggests that GalT functions as the ZP3 receptor that is responsible for inducing the acrosome reaction, whereas initial sperm-zona binding is dictated by other sperm surface receptors. Consistent with this, at least three other zona pellucida monosaccharides have been implicated in sperm binding, and novel sperm surface glycoproteins have been suggested to function in gamete binding. A large scaffolding protein has been identified that associates with the GalT cytoplasmic domain and may be responsible for orchestrating its signal transduction capacities that lead to the acrosome reaction.

Acrosome Reaction↗
PubMed2001

Mechanical ventilation-induced air-space enlargement during experimental pneumonia in piglets.

Mechanical ventilation-induced air-space enlargement was investigated in a porcine model of multifocal pneumonia. Following the intrabronchial inoculation of Escherichia coli, 9 piglets (22 +/- 2 kg) were ventilated with a tidal volume (VT) of 15 ml/kg for 43 +/- 15 h. Five noninoculated piglets ventilated for 60 h with the same VT served as control animals. Following death, the lungs were fixed and lung morphometry was assessed. In inoculated animals, unventilated infected and normally ventilated noninfected pulmonary lobules coexisted. In normally ventilated lung regions (1) emphysema-like lesions were present, (2) mean alveolar area and mean linear intercept were significantly greater in inoculated than in control animals, and (3) the degree of alveolar distension correlated with the decrease in respiratory compliance. In unventilated lung areas (1) pseudocysts were frequent, (2) alveolar edema was rare, (3) bronchiolectasis was frequent, (4) mean bronchiolar area was greater in inoculated than in control animals, and (5) the degree of bronchiolar distension correlated with the increase in inspiratory plateau pressure. In conclusion, in piglets with severe bronchopneumonia, air-space enlargement rather than pulmonary edema was the major feature of mechanical ventilation-induced lung barotrauma and resembled lesions previously reported in critically ill patients ventilated using high inspiratory pressures.

Analysis of Variance↗
PubMed2001

Computed tomography assessment of positive end-expiratory pressure-induced alveolar recruitment in patients with acute respiratory distress syndrome.

Computed tomography (CT) assessment of positive end-expiratory pressure (PEEP)-induced alveolar recruitment is classically achieved by quantifying the decrease in nonaerated lung parenchyma on a single juxtadiaphragmatic section (Gattinoni's method). This approach ignores the alveolar recruitment occurring in poorly aerated lung areas and may not reflect the alveolar recruitment of the entire lung. This study describes a new CT method in which PEEP-induced alveolar recruitment is computed as the volume of gas penetrating in poorly and nonaerated lung regions following PEEP. In 16 patients with acute respiratory distress syndrome a thoracic spiral CT scan was performed in ZEEP and PEEP 15 cm H(2)O. According to the new method, PEEP induced a 119% increase in functional residual capacity (FRC). PEEP-induced alveolar recruitment was 499 +/- 279 ml whereas distension and overdistension of previously aerated lung areas were 395 +/- 382 ml and 28 +/- 6 ml, respectively. The alveolar recruitment according to Gattinoni's method was 26 +/- 24 g and no correlation was found between both methods. A significant correlation was found between PEEP-induced alveolar recruitment and increase in Pa(O(2)) only when recruitment was assessed by the new method (Rho = 0.76, p = 0.003), suggesting that it may be more accurate than Gattinoni's method.

Aged↗
PubMed2001

Mental health in Asia: social improvements and challenges.

Remarkable improvements in economic conditions and a considerable upgrade in the quality of life have been observed in many parts of Asia during the past several decades. At the same time, many mental health challenges face the people of Asia. Various social mental health indexes are reviewed here, with available data from China, Japan, Korea, Singapore, Malaysia, and other Asian societies. The data are compared with data from the United States, Australia in the Pacific Rim, and some other Western countries to examine patterns of similarity or difference between East and West in the process of modernization. Common trends in mental health issues associated with rapid sociocultural change observed in different Asian societies are discussed, as well as the relative shortage of mental health personnel available in many Asian societies. It is emphasized that, in addition to expanding psychiatric services, there is an even more urgent need to promote mental health knowledge and concern through education in the general population. Mental health needs to be cultivated and maintained by social forces and cultural strengths. It is stressed that there is a challenge for Asian people to advance mental health beyond economic development in the 21st century.

Asia↗