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Biomedical subjects

Lei Chen

Publications and source records attributed to Lei Chen.

At least 109 records · Page 6Linked to original sources
PubMed2005

Establishment and maintenance of Kaposi's sarcoma-associated herpesvirus latency in B cells.

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is the infectious cause of Kaposi's sarcoma and is also associated with two B-cell lymphoproliferative diseases, primary effusion lymphoma and the plasmablastic form of multicentric Castleman's disease. KSHV is also found in the B-cell fraction of peripheral blood mononucleocytes of some KS patients. Despite in vivo infection of B cells and the ability of KSHV to infect many cell types in culture, to date B cells in culture have been resistant to KSHV infection. However, as shown here, the lack of infection is not due to the inability of B cells to support latent KSHV infection. When KSHV DNA is introduced into B cells, the virus is maintained as an episome and can establish and maintain latency over the course of months. As in all primary effusion lymphoma cell lines, there is a low level of spontaneous lytic replication in latently infected BJAB cells. Importantly, viral gene expression is similar to that of primary effusion lymphoma cell lines. Furthermore, the virus can be reactivated to higher levels with specific stimuli and transmitted to other cells, indicating that this is a productive infection. Thus B cells in culture are capable of establishing, maintaining, and reactivating from latency. These studies provide a controlled system to analyze how KSHV alters B cells during KSHV latency and reactivation.

Animals↗
PubMed2005

Physician knowledge and management of children exposed to domestic violence in Ohio: a comparison of pediatricians and family physicians.

Active members of the Ohio chapters of American Academy of Family Physicians (FP=1,498) and American Academy of Pediatrics (Ped=1,725) were surveyed about their knowledge and management regarding children exposed to domestic violence (DV). Characteristics of respondents were analyzed by use of Chi-square analysis. Logistic regression was performed to identify predictors of DV knowledge and management. The response rate was 33.3%. Family physicians were more likely to know their local DV agency and recognize the adult symptoms of DV, such as unexplained injury. Pediatricians were more likely to report the child who saw a fight between parents to child protective services. Continuing work to increase physicians' comfort and ability to assess for DV and manage exposed children is needed.

Adult↗
PubMed2005

Utility of bedside bladder ultrasound before urethral catheterization in young children.

BACKGROUND: Urethral catheterization is the method of choice for obtaining samples for urine culture and urine analysis in infants. Before the procedure, there is little certainty of the presence or amount of urine in the bladder. Consequently, this relatively invasive and uncomfortable procedure often needs to be repeated. The newly available technology of portable ultrasound may be useful in reducing the number of unsuccessful procedures. OBJECTIVE: To investigate the utility of bedside ultrasound of the bladder performed by pediatric emergency medicine physicians before catheterization in reducing the number of unsuccessful attempts. METHODS: A prospective, 2-phase study was performed in the setting of an urban pediatric emergency department from August 2003 to February 2004. Children who were between the ages of 0 and 24 months were enrolled. During the observation phase, the amount of urine obtained during the first catheterization was recorded for each patient. During the intervention period, a rapid bedside ultrasound of the bladder was performed by a pediatric emergency medicine physician immediately before urethral catheterization. When a sufficient amount of urine was seen, catheterization was conducted as usual. Otherwise, catheterization was deferred and repeated ultrasound was performed at 30-minute intervals until sufficient urine was identified. The amount of urine obtained was recorded. RESULTS: During the observation phase, 136 infants underwent urethral catheterization. Overall, the rate of success during the first attempt, defined as obtaining >2 mL of urine, sufficient for culture and other routine studies, was 72% (95% confidence interval: 66%-78%). A total of 112 subjects were enrolled during the intervention phase. Sufficient urine was identified on the first ultrasound in 76% (n = 85) of the patients. Among these, 98% (n = 83) underwent successful urethral catheterization during the first attempt. Among those in whom insufficient urine was identified initially (n = 27; 24%), subsequent ultrasound revealed sufficient amount in all patients within 90 minutes. Among these, 93% (n = 25) underwent successful urethral catheterization during the first attempt. Overall rate of success of initial urethral catheterization during the intervention phase was 96% (95% confidence interval: 93%-99%). Compared with the success rate during the observation phase, the differences were statistically significant. The results were consistent after being adjusted for gender. CONCLUSION: A rapid bedside ultrasound of the bladder performed by pediatric emergency physicians led to an increased success rate of urethral catheterization in children who were younger than 2 years. We were able to avoid repeated invasive testing with a simple noninvasive procedure.

Emergency Medicine↗
PubMed2005

[Treatment of lower limb ischemia with combination of traditional Chinese medicine and transplantation of autologous bone marrow mononuclear cells: a report of 23 cases].

OBJECTIVE: To evaluate the therapeutic effect of transplantation of autologous bone marrow mononuclear cells combined with traditional Chinese medicine for the treatment of limb ischemia. METHODS: Twenty-three patients with limb ischemia were treated. G-CSF was used to stimulate the bone marrow. The mononuclear cells were separated from the aspirated bone marrow fluid in the stem cell studio. The cell amount was above 1x10(9). The transplantation was performed by the way of intra-muscular multi-injection. Traditional Chinese medicine for replenishing qi to activate blood was prescribed from the first day after operation. The pain, poikilothermia, ulcer or necrosis and ankle/brachial index (ABI) of the ischemic limb were evaluated before and after the treatment. RESULTS: The pain score and poikilothermia score decreased one month after the transplantation, with distinct differences as compared with the scores before the treatment (P<0.05). The ABI increased gradually after the treatment, and one month after the treatment, it was 0.15 higher than that before the treatment. CONCLUSION: Transplantation of autologous bone marrow mononuclear cells combined with traditional Chinese medicine can decrease the symptoms and signs of severe lower limb ischemia effectively, and improve the circulation of the ischemic area.

Adult↗
PubMed2005

Small cell carcinoma of the ovary with hypercalcemia and ectopic parathyroid hormone production.

Small cell carcinoma of the ovary is a rare malignant tumor of the ovary. It is the most common undifferentiated ovarian carcinoma in young women. Approximately two thirds of patients with ovarian small cell carcinoma have hypercalcemia. The mechanism of development of hypercalcemia is unclear, although parathyroid hormone-related protein has been found in some of the cases. Parathormone expression in tumor cells, rarely reported, was seen in this case, suggesting that ectopic parathyroid hormone production by the tumor cells may be the cause of hypercalcemia.

Adult↗
PubMed2005

[Clinical analysis of 1 423 cases of root canal therapy].

OBJECTIVE: To evaluate the clinical quality of root canal therapy (RCT) in West China Dental Hospital of Sichuan University. METHODS: 1 423 RCT teeth were finished from Mar. 2001 to Feb. 2002 in West China Dental Hospital. Root canal filling quality and treatment period of these teeth were evaluated. 695 teeth of the total were revisited 2 years later and 2-year success rate were evaluated. RESULTS: The ratios of adequate filling, underfilling, and overfilling were 79.97%, 14.62% and 5.41%, receptively. Full canal RCT ratio of molar was 89.44%. Average RCT treatment period was 2.8 weeks. 2-year success rate of RCT was 94.39%. CONCLUSION: Clinical RCT level of West China Dental Hospital was satisfactory from 2001 to 2002.

Adult↗
PubMed2005

[Study on the mechanism of the interaction of methylene blue and sulfation pachymaran].

In order to understand the mechanism of the interaction of sulfate polysaccharides and small molecules at molecular level, the structure of pachymaran was decorated by Wolfrom, and sulfation pachymaran (SP) was prepared. The maximum binding number (N = 54) and the binding equilibrium constant (K = 1.563 x 10(6)) of the sulfation pachymaran and methylene blue (MB) were obtained by the exoterica model. The influence of the molar ratio of MB/SP, ethanol, hydroxypropyl-beta-cyclodextrin, Triton X-100 and NaCl on the spectra of MB-SP complex was investigated. The mechanism of the color changes of methylene blue and sulfation pachymaran reaction system has been discussed. The authors draw the conclusion that the color changes result mainly from the hydrophobic interaction between methylene blue molecules binding on sulfation pachymaran on the base of the electrostatic interaction of methylene blue and sulfation pachymaran.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2005

[The effects of recombinant human growth hormone on mandibular bone loss with or without teeth in the ovariectomized rats].

PURPOSE: To investigate the effects of recombinant human growth hormone(rh-GH )on mandibular bone loss with or without teeth in the ovariectomized rats. METHODS: Three-month aged ovariectomized rats were utilized as postmenopausal osteoporosis models and all the molars in left mandibles were extracted. After operations, the rats began to receive rh-GH 1 mg.kg(-1).d(-1) with subcutaneous injection for ten days. Weight of the rats ,mineral density of the mandibular bone and 3 other parameters were measured at 8th week and 12th week. The data was analyzed with F and t test. RESULTS: The weight of the rats increased and mandibular bone mineral density of the rats were significantly improved after rh-GH treatment, P<0.05. CONCLUSION: Rh-GH can increase the weight of the old rats and restore mandibular bone mass in mandibles with or without teeth.

Animals↗
PubMed2005

[Bacteriological surveillance in a burn intensive care unit and the analysis of bacterial resistance to antibiotics].

OBJECTIVE: To investigate the dynamic changes of the bacterial flora in our burn intensive care unit (ICU) in the past 6 years, and to analyze resistance of bacteria to various antibiotics. METHODS: A retrospective analysis of bacterial culture and drug-sensitivity results from 209 patients in our burn intensive care unit during a period of 1998 to 2003 was carried out. RESULTS: Eight hundred and forty-five strains of bacteria were isolated from 209 specimens, among which 486 strains were gram negative (G(-)) (57.51%), and 339 were gram positive (G(+)) (40.12%). Among all the G(+) bacteria, Enterococcus faecalis accounted for 34.51%, Staphylococcus aureus accounted for 31.27%, and 72.64% of Staphylococcus aureus strains were MRSA. Pseudomonas aeruginosa was predominant among all G(-) bacteria, and it accounted for 66.26% of the latter. All the bacteria isolated showed multiple resistance to antibiotics. CONCLUSION: G(-) bacilli were still predominant in our burn intensive care unit. The isolated bacteria exhibited multiple resistance to antibiotics. The results imply that antibiotics should be administered rationally in the burn wards guided by the bacterial resistance test.

Adolescent↗
PubMed2005

Effect of polymorphism of uncoupling protein 3 gene -55 (C>T) on the resting energy expenditure, total body fat and regional body fat in Chinese.

OBJECTIVE: To investigate the relationship of the C to T variant at the -55 site of the promoter region of uncoupling protein 3 gene (UCP3) with the resting energy expenditure and the parameters of body fat in Chinese population. METHODS: Three hundred Chinese (91 normal weight subjects, 209 overweight/obesity subjects) were genotyped for the UCP3 gene -55(C>T) by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Resting energy expenditure (REE), fat mass (FM), fat free mass (FFM) and the parameters for regional adipose tissue distribution were measured. RESULTS: Genotype frequencies of UCP3 gene -55(C>T) were not associated with obesity and different types of obesity. The REE level in normal weight subjects with TT homozygotes was higher than that in those with CT heterozygotes and CC homozygotes (P=0.0200). Similar tendency was also observed in overweight/obesity subjects. The FM/FFM exhibited significant difference between the overweight/obesity subjects with a TT genotype and those with a CT or CC genotype (P=0.0096). CONCLUSION: The level of difference in REE caused by the polymorphism of promoter region of UCP3 -55(C>T) may play a role in energy metabolism in Chinese.

Adipose Tissue↗
PubMed2004

ZNF322, a novel human C2H2 Kruppel-like zinc-finger protein, regulates transcriptional activation in MAPK signaling pathways.

Cardiac differentiation involves a cascade of coordinated gene expression that regulates cell proliferation and matrix protein formation in a defined temporal-spatial manner. The C(2)H(2) zinc finger-containing transcription factors have been implicated as critical regulators of multiple cardiac-expressed genes and are important for human heart development and diseases. Here we have identified and characterized a novel zinc-finger gene named ZNF322 using degenerated primers from a human embryo heart cDNA library. The gene contains four exons and spans 23.2kb in chromosome 6p22.1 region, and transcribes a 2.7kb mRNA that encodes a protein with 402 amino acid residues. The predicted protein contains 9 tandem C(2)H(2)-type zinc-finger motifs. Northern blot analysis shows that ZNF322 is expressed in every human tissue examined at adult stage and during embryonic developmental stages from 80 days to 24 weeks. When overexpressed in COS-7 cells, ZNF322-EGFP fusion protein is detected in the nucleus and cytoplasm. Reporter gene assays show that ZNF322 is a transcriptional activator. Furthermore, overexpression of ZNF322 in COS-7 cells activates the transcriptional activity of SRE and AP-1. Together, these results suggest that ZNF322 is a member of the zinc-finger transcription factor family and may act as a positive regulator in gene transcription mediated by the MAPK signaling pathways.

Amino Acid Sequence↗
PubMed2004

[The significance of pepsinogen with its subgroup and CA72-4 associate detect applied to early diagnostic and prognosis judgment on gastric cancer].

OBJECTIVE: To find out the connection of serum pepsinogen and it's subgroups (PGI, PGII) with CA72-4 to early diagnosis and postoperative recurrence on gastric cancer. METHODS: RIA was applied to detect the results of serum PGI, PGII and CA72-4 on gastric cancer and other stomach diseases, then the clinic value of associating detection on gastric cancer diagnosis and prognosis judgment were assessed. RESULTS: The serum PG levels of GC patients were significantly lower comparing to those of healthy controls (P < 0.01), apparent changes had taken place on earlier period GC (P < 0.05), and aggressive GC were even lower (P < 0.01). On the earlier period of GC diagnosis, CA72-4 levels were not apparently different to healthy controls (P > 0.05), and aggressive GC were significantly higher (P < 0.01). Compared preoperative with postoperative, the serum PGI and PGII and CA72-4 levels were significantly different (P < 0.01). In the patients underwent total gastrectomy, both of pepsinogen levels were lower than those of subtotal or large partial gastrectomy (P < 0.05). The serum PGI, PGII and CA72-4 levels of patients with recurrence of GC after total gastrectomy were significantly higher than those without. Compared before recurrence patients with after ones, the serum PGI and PGII levels of partial gastrectomy were no apparent difference (P > 0.05), however apparent changes had taken place on CA72-4 levels. The associate detection had even higher specificity (P < 0.01). CONCLUSIONS: Apply to detect the serum PG levels on crowds, especially pGI, PGI/II levels decrease, which may be expected to become the index to earlier period GC screening. The associating detection to PG and CA72-4 levels may significantly improve sensitivity and specificity, which have chances to be applied to monitoring to postoperative gastrectomy.

Adult↗
PubMed2004

[Application of hyperglycemic clamp technique in the assessment of beta-cell function in obese individuals with glucose intolerance].

OBJECTIVE: To study the changes of insulin secretion in Chinese individuals with impaired glucose tolerance and diabetes and the relationship between insulin release and overweight/obesity. METHODS: Sixty-four individuals were divided into 6 groups according to glucose tolerance (GT) and body weight: normal weight with normal glucose tolerance (NW-NGT) group, NW with impaired glucose tolerance (NW-IGT) group, NW with diabetes (NW-DM) group, overweight or obese (OW/OB) with NGT (OW/OB-NGT) group, OW/OB with IGT (OW/OB-IGT) group, OW/OB with DM (OW/OB-DM) group. The subjects were required to fast for 12 hours and then underwent oral glucose tolerance test (OGTT) and hyperglycemic clamp. RESULTS: 1. The first-phase insulin release, the sum of insulin concentrations during the first 10 minutes (at the 2(nd), 4(th), 6(th), 8(th), and 10(th) minutes) were 186 mU/L +/- 38 mU/L in the IGT groups, significantly lower than that of the NGT groups (P = 0.001). The first-phase insulin release of the DM groups was 71 mU/L +/- 10 mU/L, significantly lower than those of the NW-NGT group and IGT group (257 mU/L +/- 22 mU/L and 164 mU/L +/- 47 mU/L respectively, both P < 0.01). The second-phase insulin release, the average insulin concentration during the 20th to 150th minutes of the DM groups was 31 mU/L +/- 4 mU/L, significantly lower than those of the NGT and IGT groups (74 mU/L +/- 5 mU/L and 45 mU/L +/- 19 mU/L, P < 0.01 and P < 0.04). The 2nd-phase insulin release was not significantly different between the NGT and IGT groups (P = 0.13). The maximum insulin release (INS-Max), the average insulin concentration during the last 30 minutes (120th to 150th minutes), of the DM groups was 40 mU/L +/- 6 mU/L, significantly lower than those of the NGT and IGT groups (P < 0.05). The INS-MAX was not significantly different between the NGT and IGT groups (P = 0.12). The first-phase insulin release, second-phase insulin release, and INS-MAX of the NW-IGT group were 164 mU/L +/- 47 mU/L, 45 mU/L +/- 19 mU/L, and 53 mU/L +/- 22 mU/L respectively, all significantly higher than those of the NW-IGT group (61 mU/L +/- 17 mU/L, 27 mU/L +/- 5 mU/L, and 34 mU/L +/- 6 mU/L respectively, P < 0.05) and those of the DM groups (61 mU/L +/- 17 mU/L, 27 mU/L +/- 5 mU/L, and 34 mU/L +/- 6 mU/L respectively, P < 0.05). 3. The first-phase insulin release, second-phase insulin release, and INS-MAX of the OW/OB-NGT group were 546 mU/L +/- 62 mU/L, 138 mU/L +/- 18 mU/L, and 163 mU/L +/- 24 mU/L respectively, all significantly higher than those of the NW-NGT group (257 mU/L +/- 22 mU/L, 74 mU/L +/- 6 mU/L, and 97 mU/L +/- 8 mU/L, respectively, P < 0.05). The first- phase insulin secretion in the OW/OB-IGT group and OW/OB-DM group were 201 mU/L +/- 47 mU/L and 82 mU/L +/- 9 mU/L respectively, both significantly lower than that of the OW/OB- NGT group (P < 0.05). CONCLUSION: 1. The insulin release is progressively decreased in Chinese individuals with IGT and DM. The individuals with IGT have lower first phase insulin release. In addition to decreased first phase insulin release, subjects with DM have reduced second-phase and maximum insulin release. 2. Simply overweight/obese individuals have higher insulin secretion, while overweight or obese individuals with IGT and DM have reduced first phase insulin release.

Adult↗
PubMed2004

Novel fragmentation reaction of 2-alkyl- and 2,4-dialkyl-3-iodo-1-oxocyclohexan-2,4-carbolactones.

2-Alkyl- and 2,4-dialkyl-3-iodo-1-oxocyclohexan-2,4-carbolactones undergo lithium hydroxide- and lithium alkoxide-induced fragmentation reactions to provide butenolides, gamma-hydroxycyclohexenones, and/or gamma-butyrolactones. In general, product distribution is governed by two factors: (1) the nature of nucleophiles and (2) the steric bulkiness of the substituents at C-2 and C-4 of the cyclohexanones. Lithium hydroxide-induced fragmentation provides butenolides and gamma-hydroxycyclohexenones. In contrast, lithium alkoxide-promoted fragmentation results in predominantly 5-substituted gamma-butyrolactones along with a small amount of butenolides in limited cases. Fragmentation products induced by lithium hydroxide are largely influenced by the steric bulkiness of the substituents at C-2 and C-4 of the cyclohexanone ring. The bulky substituents render the exclusive formation of butenolides.

Catalysis↗
PubMed2004

Retroviral pseudotransduction for targeted cell manipulation.

The present study addressed whether retroviral vectors could be modified to achieve receptor-mediated, dose-controlled, and transient delivery of proteins or nucleic acids into targeted cells. As a paradigm, we generated mouse leukemia virus-based vectors encoding the site-specific recombinase Cre. The vectors were disabled in primer binding site function, blocking reverse transcription of the virion mRNA. While reducing transgene insertion more than 1000-fold and abolishing toxic effects of constitutive Cre expression, transient Cre delivery was still highly efficient, receptor restricted, and insensitive to pharmacologic inhibition of reverse transcription. This form of Cre transfer required the retroviral packaging signal, cap-proximal positioning of the translation unit, as well as gag and env expression in producer cells, revealing retroviral mRNA transfer as the underlying mechanism. Thus, retrovirally delivered mRNA may serve as an immediate translation template if not being reverse transcribed. This approach allows multiple modifications for targeted and reversible cell manipulation with nucleic acids.

Animals↗
PubMed2004

Cylindrically symmetric electrohydrodynamic patterning.

Cylindrically symmetric structures such as concentric rings and rosettes arise out of thin polymeric films subjected to strong electric fields. Experiments that formed concentric rings and theory capable of explaining these and other cylindrical structures are presented. These rings represent an additional member of a class of structures, including pillars and holes, formed by electrohydrodynamic patterning of thin films, occasionally referred to as lithographically induced self-assembly. Fabrication of a set of concentric rings begins by spin coating a thin poly(methyl methacrylate) film onto a silicon wafer. A mask is superimposed parallel to the film leaving a similarly thin air gap. Electric fields, acting in opposition to surface tension, destabilize the free interface when raised above the glass transition temperature. Central pillars nucleate under small cylindrical protrusions patterned on the mask. Rings then emerge sequentially, with larger systems having as many as 10 fully formed rings. Ring-to-ring spacings and annular widths, typically on the order of a micron, are approximately constant within a concentric cluster. The formation rate is proportional to the viscosity and, consequently, has the expected Williams-Landel-Ferry dependence on temperature. In light of these developments we have undertaken a linear stability analysis in cylindrical coordinates to describe these rings and ringlike structures. The salient feature of this analysis is the use of perturbations that incorporate their radial dependence in terms of Bessel functions as opposed to the traditional sinusoids of Cartesian coordinates. The theory predicts approximately constant ring-to-ring spacings, constant annular widths, and growth rates that agree with experiment. A secondary instability is observed at higher temperatures, which causes the rings to segment into arcs or pillar arrays. The cylindrical theory may be generalized to describe hexagonal pillar/hole packing, gratings, and rosettes with the first being of particular importance given the ubiquitous observation of hexagonal packing. The perturbation analysis presented here is relevant to any system with cylindrical symmetry, for which the radial dependence can be described in terms of Bessel functions.

Journal Article↗
PubMed2004

Combination immunotherapy of B-cell non-Hodgkin's lymphoma with rituximab and interleukin-2: a preclinical and phase I study.

PURPOSE: Cytokine-induced modulation of innate immunity is being explored to enhance the activity of monoclonal antibodies. Severe combined immunodeficient (SCID) mice engrafted with peripheral blood leukocytes (PBLs) from Epstein Barr virus-seropositive donors develop human B-cell non-Hodgkin's lymphomas [B-NHLs (hu-PBL-SCID mouse model)]. We used this hu-PBL-SCID mouse model to study the synergism between interleukin (IL)-2 and rituximab. We also conducted a phase I trial of IL-2 and rituximab in relapsed B-NHL to study whether expansion of natural killer (NK) cells and enhanced cellular cytotoxicity could be safely accomplished in vivo. EXPERIMENTAL DESIGN: Hu-PBL-SCID mice were treated with various schedules of rituximab and IL-2, with survival as the end point. Patients with relapsed B-NHL received rituximab (375 mg/m2 weekly x 4) followed by daily low-dose IL-2 (1 MIU/m2/day x 4 weeks) with pulses of intermediate-dose IL-2 (3-15 MIU/m2). Toxicity, NK cell numbers, and cellular cytotoxicity were measured. RESULTS: In the hu-PBL-SCID mouse, the combination of rituximab and IL-2 showed greater activity against B-NHL than either agent alone. Treatment was most effective when IL-2 was given before rituximab. Twelve patients with heavily pretreated B-NHL entered the phase I trial. Toxicity was manageable, and responses were observed. NK cell expansion and enhanced cellular cytotoxicity against a B-cell lymphoma target were observed but did not correlate with response. CONCLUSIONS: The combination of IL-2 and rituximab is synergistic against B-NHL in the hu-PBL-SCID model. In the phase I trial, a sequential combination of rituximab and IL-2 was well tolerated and achieved biological end points. Responses were observed.

Adult↗