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Biomedical subjects

J Leng

Publications and source records attributed to J Leng.

At least 19 recordsLinked to original sources
PubMed2006

Impact of different pressures and exposure times of a simulated carbon dioxide pneumoperitoneum environment on proliferation and apoptosis of human ovarian cancer cell lines.

BACKGROUND: This study aimed too evaluate the proliferation and apoptosis of human ovarian cancer cell lines HO8910 and SKOV3 after exposure to a simulated laparoscopic carbon dioxide (CO2) pneumoperitoneum environment at different pressures and lengths of exposure time. METHODS: The effects of the simulated laparoscopic CO2 pneumoperitoneum environment at different CO2 pressures (0-16 mmHg) and exposure times (1-4 h) on tumor cell growth and apoptosis were assessed by 3-[4,5-Dimethylthiazol]-2; 5-diphenyltetrazolium bromide (MTT) chromometry and proliferative index (PI) staining or Annexin V and PI double-staining flow cytometry. Cells cultured in a standard environment were used as the control group. RESULTS: In this study, HO8910 cell growth tended to slow down with the increase in CO2 pressure and exposure time. A significantly lower PI was observed at 72 h of culture after exposure to both 8 and 16 mmHg of pressure, as compared with the control and 0 mmHg pressure group (p < 0.05). The PI of SKOV3 cells tended to decline after exposure. Significantly lower PI was observed in the group with exposure to 16 mmHg for 4 h over a 72-h period, as compared with the control groups exposed to 0 mmHg (p < 0.05). The inhibition of cell growth was associated with an increase in the proportion of cells at stage G1. The apoptotic index and the percentage of apoptotic cells tended to increase with an increase in pressure and a prolonged time of exposure. CONCLUSIONS: The results suggest inhibited cell proliferation and increased cell apoptosis of human ovarian cancer cells were positively related to CO2 pressure and exposure time.

Apoptosis↗
PubMed2004

New York City syndromic surveillance systems.

New York City's first syndromic surveillance systems were established in 1995 to detect outbreaks of waterborne illness. In 1998, daily monitoring of ambulance dispatch calls for influenza-like illness began. After the 2001 World Trade Center attacks, concern about biologic terrorism led to the development of surveillance systems to track chief complaints of patients reporting to emergency departments, over-the-counter and prescription pharmacy sales, and worker absenteeism. These systems have proved useful for detecting substantial citywide increases in common viral illnesses (e.g., influenza, norovirus, and rotavirus). However, the systems have not detected more contained outbreaks earlier than traditional surveillance. Future plans include monitoring school health and outpatient clinic visits, augmenting laboratory testing to confirm syndromic signals, and conducting evaluation studies to identify which of these systems will be continued for the long term.

Bioterrorism↗
PubMed2004

Evaporation of liquids and solutions in confined geometry.

We describe a drying setup where a liquid droplet is confined between two circular glass plates and allowed to evaporate. Optical imaging of the shrinking droplet provides the temporal evolution of the solvent volume. For a pure liquid, we measure the diffusion coefficient of the evaporating gas with a good accuracy. For a solution, the slowing down of evaporation by progessive concentration of the solute yields a direct measurement of the solvent activity.

Journal Article↗
PubMed2004

Endobronchial eosinophils preferentially stimulate T helper cell type 2 responses.

BACKGROUND: Antigen-loaded eosinophils instilled intratracheally into mice were capable of migrating into local lymph nodes and localize to the T cell-rich paracortical zones where they stimulated antigen-specific proliferation of CD4+ T cells. The aim of the present study was to evaluate whether eosinophils within the tracheobronchial lumen can stimulate Th2 cell expansion by presenting antigen both in vitro and in vivo. METHODS: Airway eosinophils were recovered from ovalbumin-sensitized and -challenged BALB/c mice, these eosinophils were then co-cultured with sensitized CD4+ cells in the absence or presence of anti-CD80 or/and -CD86 monoclonal antibodies. Airway eosinophils were instilled into the trachea of sensitized mice. At 3 days thereafter, the draining paratracheal lymph nodes were removed and teased into cell suspensions for culture. Cell-free culture supernatants were collected for detection of cytokines. RESULTS: Our data showed that airway eosinophils functioned as CD80- and CD86-dependent antigen-presenting cells (APCs) to stimulate sensitized CD4+ lymphocytes to produce interleukin (IL)-4, IL-5, and IL-13, but not interferon (IFN)-gamma in in vitro assay. When instilled intratracheally in sensitized recipient mice, airway eosinophils migrated into draining paratracheal lymph nodes primed Th2 cells in vivo for IL-4, IL-5, and IL-13, but not IFN-gamma, production during the in vitro culture that was also CD80- and CD86-dependent. CONCLUSION: Eosinophils within the lumina of airways could process inhaled antigen function in vitro and in vivo as APCs to promote expansion of Th2 cells. This investigation highlights the potential of eosinophils to not only act as terminal effector cells but also to actively modulate immune responses by amplifying Th2 cell responses.

Animals↗
PubMed2003

Kinetics of the micelle-to-vesicle transition: aqueous lecithin-bile salt mixtures.

Important routes to lipid vesicles (liposomes) are detergent removal techniques, such as dialysis or dilution. Although they are widely applied, there has been only limited understanding about the structural evolution during the formation of vesicles and the parameters that determine their properties. We use time-resolved static and dynamic light scattering to study vesicle formation in aqueous lecithin-bile salt mixtures. The kinetic rates and vesicle sizes are found to strongly depend on total amphiphile concentration and, even more pronounced, on ionic strength. The observed trends contradict equilibrium calculations, but are in agreement with a kinetic model that we present. This model identifies the key kinetic steps during vesicle formation: rapid formation of disk-like intermediate micelles, growth of these metastable micelles, and their closure to form vesicles once line tension dominates bending energy. A comparison of the rates of growth and closure provides a kinetic criterion for the critical size at which disks close and thus for the vesicle size. The model suggests that liposomes are nonequilibrium, kinetically trapped structures of very long lifetime. Their properties are hence controlled by kinetics rather than thermodynamics.

Animals↗
PubMed2001

Oscillating viscosity in a lyotropic lamellar phase under shear flow.

We report some time-dependent behavior of lyotropic lamellar phase under shear flow. At fixed stress, near a layering instability, the system presents an oscillating shear rate. We build up a new stress versus shear rate diagram that includes temporal behavior. This diagram is made of two distinct branches of stationary states which correspond, respectively, to disordered and ordered multilamellar vesicle phases. When increasing the shear stress, prior to the transition to the ordered structural state, sustained oscillations of the viscosity are recorded. They correspond to periodic structural change of the entire sample between a disordered and a ordered state of multilamellar vesicles.

Journal Article↗
PubMed2001

[Complications in laparoscopic gynecologic surgery: analysis of 34 cases].

OBJECTIVE: To investigate retrospectively the complication rate of gynecological laparoscopies at Peking union medical college (PUMC) hospital over 6-year period. METHODS: 1,769 laparoscopic surgeries were carried out from Jan. 1994 through Oct. 1999. The procedures included 1,421 adnexal surgeries, 52 myomectomies and 296 laparoscopic assisted vaginal hysterectomy (LAVH). Complication was defined as an event that had modified the usual course of the procedure or of the postoperative period. RESULTS: Complications occurred in 34 cases, the overall complication rate was 1.9%. Unintended laparotomies occurred in 6 cases (0.3%). Complication rate was 0.9%, 1.9% and 6.8% in adnexal surgeries, myomectomies and LAVH respectively. 12 (35.3%) complications related to puncture and pneumoperitoneum, including five severe emphysema, 7 injuries to epigastric blood vessels of abdominal wall and omental blood vessel, this figure represented 35.3% of all complications of this series. 5 (14.7%) intraoperative, complications occurred during the laparoscopic surgery (3 severe bleedings, 1 bladder injury and 1 skin burn of leg related to the electrode plate), laparotomy was required in 4 of these cases. 17 (50.0%) complications occurred during postoperative stage: 2 intraperitoneal hemorrhages needing re-laparotomy, 2 bowel complications, 4 nerve paresis and 9 febrile morbidities. CONCLUSIONS: In our experience, operative gynecologic laparoscopy is associated with acceptable morbidity rate, but can not be overlooked. Complications seems related to advanced procedures such as LAVH.

Female↗
PubMed2001

Laparoscopic myomectomy.

OBJECTIVE: To investigate the indications, surgical techniques and complications of laparoscopic myomectomy. MATERIALS AND METHODS: A retrospective study was carried out in 74 patients with fibroids > 3 cm from March, 1995 until May, 2000 at PUMC Hospital. Indications for surgery were symptomatic fibroids (20 cases), mainly pain or urine frequency; progressively increasing fibroid size (7 cases); coexistent adnexal pathology(26 cases) and infertility(21 cases). RESULTS: The number of fibroids of each patient varied from 1 to 4 with single fibroid of 62 cases (83.7%). The fibroids were located in anterior wall (30 cases), posterior wall (23 cases) and fundus (21 cases). A total of 93 fibroids were removed from these patients including 16 intramural fibroids and 77 subserous fibroids. The size of dominant fibroids ranged from 3 approximately 8 cm (mean 4.8 cm). In 19 cases (25.6%), the uterine wall was sutured in one layer. Mean duration of operation was 73 minutes and mean blood loss was 82 ml. Longer operating time and more blood loss were observed in patients with fibroids > or = 4 cm than those with fibroids < 4 cm. The difference was statistically significant ( P < 0.05). Mean postoperative hospital stay was 3.2 days and overall complication rate was 1.4%. The average postoperative follow-up period was 22 months (1 approximately 62 months). All the patients with symptoms showed remission of their complaints at 2-month follow-up. Recurrence of fibroid occurred in 1 case 1 year after initial operation and second laparoscopic myomectomy was given to her successfully. Five patients became pregnant. The pregnancy was uneventful and proceeded to selective caesarean section at term pregnancy in 4 cases. One miscarriage occured at 8 weeks in the 5th case. No adhesions at myomectomy site were found in these 5 patients. CONCLUSIONS: Our study suggests the feasibility of laparoscopic myomectomy in selected patients, which leads to effectiveness, low complication rate and satisfactory remission of symptoms. Further study on recurrence and fertility must be continued.

Adult↗
PubMed2001

[Endometriosis in adolescents: analysis of 6 cases].

OBJECTIVE: To review the diagnosis and treatment of endometriosis in adolescents and to evaluate the surgical and medical treatment options for this special population. METHOD: To review the 6 cases of adolescent endometriosis and to review the literature research. RESULTS: Three hundred and ninety nine cases under age 18 had undergone gynecological operation. So the incidence among this period is 1.8% (6/339) in hospitalized adolescents. Four cases have complicated genital tract anomalies. Preoperative diagnosis is rare. Good prognosis is expected in most patients. Only 1 case relapsed 9 years after medical therapy. Endometriosis is the most common cause of chronic pelvic pain in adolescents. There may be a natural progression of endometriosis from atypical lesions in adolescents to classic lesions in adults. Congenital abnormalities of the reproductive tract are the main reason for the adolescent endometriosis. CONCLUSIONS: Endometriosis should be strongly suspected in adolescent with chronic pelvic pain especially with no response to oral contraceptives and nonsteroidal antiinflammatory medicine. The treatment involves the surgical operation and medicine. Adolescence;

Adolescent↗
PubMed2000

Determination of matrix metalloproteinase activity using biotinylated gelatin.

Matrix metalloproteinases (MMPs) and, specifically, MMP-2 (gelatinase A) and MMP-9 (gelatinase B) are strongly associated with malignant progression and matrix remodeling. These enzymes are a subject of intensive studies involving screening of comprehensive chemical libraries of synthetic inhibitors. There is no simple method available for measurement of activity of gelatinases and related MMPs. Here, we report a simple, inexpensive, and highly sensitive assay for MMP activity. The assay performed in a 96-well microtiter plate format employs biotin-labeled gelatin (denatured collagen type I) as a substrate. Following the substrate cleavage, only the proteolytic fragments bearing biotin moieties are captured by streptavidin coated on the plastic surface and the captured fragments with at least two biotin molecules should be revealed by streptavidin conjugated with horseradish peroxidase. The frequency of lysine residues is low in collagen type I relative to the MMP cleavage sequences (PXGX). Accordingly, the majority of the cleavage products must be devoid of biotin or possess only one biotin group. Both of these types of fragments cannot be recognized by the horseradish peroxidase-streptavidin conjugate. Therefore, higher gelatinolytic activity is associated with lower signal in the assay. This 2-h assay allows identification of gelatinolytic activity of MMP-2 in concentrations as low as 0.16 ng/ml. The sensitivity of this ELISA-like assay is comparable to that of gelatin zymography, a method widely used to detect gelatinases. However, in contrast to zymography, the assay directly measures the enzymatic activity of MMP samples. The gelatinolytic activity assay permits efficient analyses and screening of the MMP inhibitor panels and allows quantitation of gelatinolytic activity of various MMPs in solution as well as on cell surfaces.

Binding Sites↗
PubMed2000

ErbB2 is necessary for induction of carcinoma cell invasion by ErbB family receptor tyrosine kinases.

The epidermal growth factor (EGF) family of tyrosine kinase receptors (ErbB1, -2, -3, and -4) and their ligands are involved in cell differentiation, proliferation, migration, and carcinogenesis. However, it has proven difficult to link a given ErbB receptor to a specific biological process since most cells express multiple ErbB members that heterodimerize, leading to receptor cross-activation. In this study, we utilize carcinoma cells depleted of ErbB2, but not other ErbB receptor members, to specifically examine the role of ErbB2 in carcinoma cell migration and invasion. Cells stimulated with EGF-related peptides show increased invasion of the extracellular matrix, whereas cells devoid of functional ErbB2 receptors do not. ErbB2 facilitates cell invasion through extracellular regulated kinase (ERK) activation and coupling of the adaptor proteins, p130CAS and c-CrkII, which regulate the actin-myosin cytoskeleton of migratory cells. Overexpression of ErbB2 in cells devoid of other ErbB receptor members is sufficient to promote ERK activation and CAS/Crk coupling, leading to cell migration. Thus, ErbB2 serves as a critical component that couples ErbB receptor tyrosine kinases to the migration/invasion machinery of carcinoma cells.

Adenocarcinoma↗
PubMed2000

Evidence of apoptotic smooth muscle cells in proliferative intima of injured arteries.

OBJECTIVE: To investigate the occurrence and extent of apoptosis in the course of restenosis. METHODS: The experimental models of vessel narrowness and intima thickness were established in minipigs' iliac arteries by balloon injury and specimens were retrieved on the 1st, 3rd, 6th, 12th and 30th days for dynamic observation. Apoptotic smooth muscle cells (SMCs) were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). RESULTS: Apoptotic SMCs occurred only in the thickened intima 12 days after injury accompanied with the proliferative SMCs, the percentage of apoptosis was 1.94% +/- 0.42% on the 12th day and 1.36% +/- 0.31% on the 30th day respectively. The low frequency of apoptosis compared with the proliferative SMCs was a feature in the restenotic pathology. CONCLUSIONS: Apoptosis participates in the pathogenetic process of intimal thickening and its level was low compared with proliferation. The findings suggest that attempts to modulate apoptosis after vessel injury constitute a theoretical approach to the prevention of restenosis.

Animals↗
PubMed2000

[Expression of bcl-2 and p16 in transitional cell carcinoma of urinary bladder].

OBJECTIVE: To study the relationship between the expression of proto-oncogene bcl-2 and MTS1/p16 in transitional cell carcinoma of bladder and prognosis. METHODS: Immunohistochemical SABC method was used to detect the expression of proto-oncogene bcl-2 and MTS1/p16 in 51 paraffin-embedded primary transitional cell carcinoma of bladder specimens and 5 normal bladder mucosa specimens. RESULTS: The positive expression of bcl-2 was seen in 80.2% (42/51) tumors. There was statistically significant correlation between prognosis and the positive expression of bcl-2. The positive expression rate was higher in tumors with poorer prognosis than in those with better prognosis (P < 0.05). The expression of p16 protein was positive in 50.9% (26 of 51) in tumors and negative in all 5 normal bladder mucosae. The positive expression rate of p16 descended with increasing grade, stage and poorer prognosis. Clinicopathological characteristics and prognosis were related to the expression of p16 (P < 0.05). The positive expression of bcl-2 versus negative expression of p16 were seen in 20 of 51 of tumors, with distributing grade I 3/11, grade II 9/26, grade III 8/14, Tis - T(1) 6/28, T(2) 10/17, T(3) 4/6, A group 5/20, B group 4/16, and C group 11/15, respectively. Both bcl-2 and p16 were positively expressed in 22 of 51 of tumors. Their positive expressions were higher in tumors with lower grade, stage and better prognosis than in those with worse clinicopathological characteristics and poorer prognosis (P < 0.05). CONCLUSIONS: Over-expression of bcl-2 appears to be common in bladder cancer; over-expression of proto-oncogene bcl-2 and inactivation of the MTS1/p16 gene are likely to be contributing factors for primary bladder cancer; and they can be the prognostic indicators for transitional cell carcinoma of urinary bladder.

Adult↗
PubMed2000

Complications in laparoscopic gynecologic surgery.

OBJECTIVE: To investigate retrospectively the complications and associated factors of gynecolgical laparoscopies. METHODS: 1 769 laparoscopic surgeries were carried out from January 1994 to October 1999 at our department. The procedures included 1421 surgeries of ovary and tube, 52 myomectomies and 296 cases of laproscopic-assisted vaginal hysterectomy (LAVH). A total of 312 patients had a history of prior laparotomy (17.6%). RESULTS: Complications occured in 34 cases, the overall complication rate was 1.92%. Unintended laparotomies occured in 6 cases (0.34%). 12 complications were associated with insertion of Veresse needle or trocar and creation of pneumoperitoneum, including 5 severe emphysema and 7 vascular injuries, this figure represents 35.3% of all complications of this series. Five intraoperative complications (14.7%) occured during the laparoscopic surgery (3 severe bleedings, one bladder injury and one skin burn of leg caused by damaged electrode plate), laparotomy was required in four of these cases. Seventeen complications occured during postoperative stage: 2 intraperitoneal hemorrhages needing laparotomy, 2 bowel injuries, 4 nerve paresis and 9 febrile morbidities. CONCLUSIONS: Operative gynecologic laparoscopy is associated with acceptable morbidity rate, but can not be overlooked. Complication rate seems to be higher in advanced procedures such as LAVH.

Female↗
PubMed1999

Potentiation of cell migration by adhesion-dependent cooperative signals from the GTPase Rac and Raf kinase.

The small GTPase Rac is thought to regulate cell movement by influencing actin cytoskeletal organization and membrane ruffling. However, cell migration also depends on the activation of mitogen-activated protein kinase (MAPK), which can regulate myosin motor function, an event critical for cell contraction. Evidence is provided that, during active cell adhesion to the extracellular matrix, Rac potentiates the MAPK pathway and influences cell migration by selectively synergizing with Raf kinase but not with Ras or MAPK kinase. In fact, the synergy between Rac and Raf kinase increases the chemotactic sensitivity of cells to epidermal growth factor by 1000-fold. Therefore, the role of Rac in cell migration not only depends on its ability to regulate actin cytoskeletal organization but also on its capacity to potentiate chemokine activation of MAPK in a manner that depends on active cell adhesion to the extracellular matrix.

3T3 Cells↗
PubMed1999

Regulation of cell contraction and membrane ruffling by distinct signals in migratory cells.

Cell migration and wound contraction requires assembly of actin into a functional myosin motor unit capable of generating force. However, cell migration also involves formation of actin-containing membrane ruffles. Evidence is provided that actin-myosin assembly and membrane ruffling are regulated by distinct signaling pathways in the migratory cell. Interaction of cells with extracellular matrix proteins or cytokines promote cell migration through activation of the MAP kinases ERK1 and ERK2 as well as the molecular coupling of the adaptor proteins p130CAS and c-CrkII. ERK signaling is independent of CAS/Crk coupling and regulates myosin light chain phosphorylation leading to actin-myosin assembly during cell migration and cell-mediated contraction of a collagen matrix. In contrast, membrane ruffling, but not cell contraction, requires Rac GTPase activity and the formation of a CAS/Crk complex that functions in the context of the Rac activating protein DOCK180. Thus, during cell migration ERK and CAS/Crk coupling operate as components of distinct signaling pathways that control actin assembly into myosin motors and membrane ruffles, respectively.

Actins↗
PubMed1999

Selective requirement for Src kinases during VEGF-induced angiogenesis and vascular permeability.

Src kinase activity was found to protect endothelial cells from apoptosis during vascular endothelial growth factor (VEGF)-, but not basic fibroblast growth factor (bFGF)-, mediated angiogenesis in chick embryos and mice. In fact, retroviral targeting of kinase-deleted Src to tumor-associated blood vessels suppressed angiogenesis and the growth of a VEGF-producing tumor. Although mice lacking individual Src family kinases (SFKs) showed normal angiogenesis, mice deficient in pp60c-src or pp62c-yes showed no VEGF-induced vascular permeability (VP), yet fyn-/- mice displayed normal VP. In contrast, inflammation-mediated VP appeared normal in Src-deficient mice. Therefore, VEGF-, but not bFGF-, mediated angiogenesis requires SFK activity in general, whereas the VP activity of VEGF specifically depends on the SFKs, Src, or Yes.

Animals↗