Biomedical subjects

L Cheng

Publications and source records attributed to L Cheng.

At least 145 records · Page 8Linked to original sources

PubMed2000

The cell cycle inhibitors p21WAF1 and p27KIP1 are associated with survival in patients treated by salvage prostatectomy after radiation therapy.

We evaluated p27KIP1 and p21WAF1 expression in 52 patients treated by salvage radical prostatectomy and bilateral pelvic lymphadenectomy for biopsy-proven locally persistent or recurrent prostate cancer after external beam radiation therapy. We defined low and high expression based on the median value observed in our sample. Five-year distant metastasis-free survival and cancer-specific survival were 71 and 82%, respectively, for patients with low expression of p21 (< or =5%), compared with 94 and 100%, respectively, for those with high expression of p21 (>5%; P = 0.02 and 0.01, respectively). Five-year distant metastasis-free survival and cancer-specific survival were 71 and 82%, respectively, for patients with low expression of p27 (<50%), compared with 88 and 96%, respectively, for those with high expression of p27 (> or =50%; P = 0.06 and 0.01, respectively). These findings indicate that p21 and p27 expression levels are significant predictors of survival for patients selected for salvage prostatectomy for recurrent prostate cancer.

Aged↗

PubMed2000

Reduced expression levels of nucleotide excision repair genes in lung cancer: a case-control analysis.

Epidemiological studies have indicated that reduced DNA repair capacity and increased DNA adduct levels are associated with increased risk of lung cancer. Nucleotide excision repair (NER) is the major pathway in humans for repairing DNA adducts induced by smoking-related carcinogens, such as benzo[a]pyrene diol epoxide. We hypothesized that genetically determined baseline expression level of genes involved in NER is associated with risk of lung cancer. In a pilot case-control study, we measured the relative expression levels of five NER genes [ERCC1, XPB/ERCC3, XPG/ERCC5, CSB/ERCC6 and XPC (ERCC, excision repair cross-complementing; CSB, Cockayne's syndrome complementary group B)] in phytohemagglutinin-stimulated peripheral lymphocytes obtained from 75 lung cancer patients and 95 controls using a newly developed multiplex RT-PCR assay. Cases and controls were matched on age, sex, ethnicity and tobacco use. The expression level of the beta-actin gene was used as an internal control for the relative quantitation. We observed a 12.2 and 12.5% decrease in the baseline expression levels of XPG/ERCC5 and CSB/ERCC6, respectively, in cases compared with controls. These differences were statistically significant (P < 0.01) when the median expression level in the controls was used as the cut-off point, the lung cancer patients were significantly more likely than the controls to have reduced expression levels of XPG/ERCC5 [odds ratio (OR), 2.32; 95% confidence interval (CI), 1.22-4.43] and CSB/ERCC6 (OR, 2.49; 95% CI, 1.28-4.84). There was also a dose-response relationship between reduced expression levels and increased lung cancer risk (trend test: P < 0.01). Our results suggest that individuals whose expression levels of XPG/ERCC5 and CSB/ERCC6 are reduced may be at higher risk of lung cancer.

Actins↗

PubMed2000

The effect of prinomastat (AG3340), a potent inhibitor of matrix metalloproteinases, on a subacute model of proliferative vitreoretinopathy.

PURPOSE: To determine the efficacy of prinomastat (AG3340), a synthetic inhibitor of matrix metalloproteinase, in the treatment of experimental proliferative vitreoretinopathy (PVR) induced by intravitreal dispase injection. METHODS: One eye each of 53 New Zealand white rabbits was injected in the vitreous cavity with 0.07 unit of dispase to induce PVR. One week after PVR induction, 53 rabbits were randomized (27:26) to receive 0.5 mg prinomastat or the vehicle of the drug (acidified water) intravitreally every two weeks. The scores of PVR severity (scale of 1-5) were graded to compare the prinomastat-treated animals with the control group. RESULTS: The average PVR scores in the treatment and control groups were 2.62 and 3.57 respectively (p = 0.038; Wilcoxon rank sum). Clinically significant PVR with retinal detachment (PVR > or = grade 3) developed in 76% of rabbits in the control group versus 51% of rabbits treated with prinomastat. CONCLUSIONS: Intravitreally administered prinomastat decreased development of PVR in an experimental model which made use of dispase to induce PVR.

Animals↗

PubMed2000

Chromium(VI)-induced mutagenesis in the lungs of big blue transgenic mice.

The mutagenic activity of the hexavalent chromium [Cr(VI)] compound potassium dichromate was examined in the Big Blue transgenic mouse lung, the target organ for Cr(VI) carcinogenesis in humans. Mice were exposed to Cr(VI) by intratracheal instillation of a potassium dichromate (K2Cr2O7) solution. Analysis of the deposition of Cr in mouse lungs revealed that the procedure reproducibly resulted in about 5% retention of the Cr in the lung. Lower but measurable levels were detected in kidney and liver. We found a dose-dependent and time-dependent increase in the mutant frequency in the mouse lung. A significant elevation of the mutant frequency above the spontaneous background was observed two weeks after Cr(VI) intratracheal instillation and at doses above 3 mg/kg. Depletion of tissue glutathione (GSH) levels by buthionine sulfoximine (BSO) before Cr(VI) treatment led to a decrease in the Cr(VI)-induced mutant frequency, compared to that in the animals with normal GSH levels, suggesting a role for GSH in the generation of reactive intermediates during the intracellular reduction of Cr(VI). Sequence analysis for the Cr(VI)-induced mutants revealed a similarity to the spontaneous mutational spectrum observed in mouse lungs, consistent with the generation of oxidative-type DNA damage by Cr(VI). These results demonstrate that Cr(VI) is mutagenic in mouse lung, the target organ for human carcinogenesis.

Animals↗

PubMed2000

Colocalization of TrkB and brain-derived neurotrophic factor proteins in green-red-sensitive cone outer segments.

PURPOSE: To examine the distribution of neurotrophins (NTs) and their catalytic receptors in adult rat photoreceptors. METHODS: Immunocytochemistry and Western blot analyses were performed using primary antibodies raised against NTs (nerve growth factor [NGF], brain-derived neurotrophic factor [BDNF], NT-3, and NT-4/5) and NT receptors (TrkA, TrkB, TrkC, and p75NTR). Double-labeling of retinal sections with opsin-specific antibodies was performed to identify each photoreceptor type. Competitive experiments using excess recombinant NT or Trk receptors confirmed the binding specificity of each antibody. RESULTS: TrkB and BDNF immunoreactivity was colocalized in cone outer segments. TrkB and BDNF were detected in all green-red-sensitive cones, but not in blue-UV cones or rods, and other NTs and NT receptors were not detected in any of the photoreceptor types. CONCLUSIONS: The findings suggest a specific role for BDNF through its signaling receptor TrkB in the function and maintenance of green-red cones, the predominant cone type in the rat retina.

Animals↗

PubMed2000

[Studies on the polymorphism of MICA gene in four Chinese populations].

OBJECTIVE: To understand with greater clearness the genetic polymorphism of (GCT)n repeat of MHC class I chain-related gene A (MICA)in some Chinese populations and provide preliminary genetic evidence for the independent origin of Chinese Baima Tibetan (BMT). METHODS: ACD-blood or saliva specimens of 411 unrelated individuals from four Chinese populations were collected. A primer pair spanning exon 5 of MICA gene was used to amplify the GCT region. Alleles were detected by PCR and denaturing PAGE. Comparison of the allelic distributions among the four populations was carried out. RESULTS: Five previously reported alleles have been observed in all the four populations, but the allelic distributions are different from one another. The most frequent allele is the A5 in all the four populations (0.325 in BMT, 0.345 in Tibetans, 0.390 in Chengdu Hans and 0.319 in Qiangs). A5.1 allele is the second most frequent allele in Chengdu Hans (0.230) and in Qiangs (0.293), while the second most frequent alleles for BMT and Tibetans are A4 (0.254) and A9 (0.272) respectively. The distribution of alleles in BMT is significantly different from that in the other three populations. CONCLUSION: Alleles of MICA gene exon 5 are conservative in all populations studied so far. The results suggest that genetically BMT might be an independent ethnic population.

Alleles↗

PubMed2000

[In vitro study of C3a des Arg produced by plasma incubation with blood purification materials].

This study was performed to evaluate the degree of complement C3 activation of five biomedical polymers (cellulose acetate (CA), polymethylmethacrylate (PMMA), polysulphone (PS), polyethersulphone (PES), sulphonated polyethersulphone(PES-SO3) which are used to make hemofilters. The concentration of the activation derivative C3a des Arg was measured by radioimmunoassay (RIA) in human plasma after incubation with these five polymers for 30, 60, 90 and 120 minutes. The experimental results indicated that the presence of polymers caused an increase in C3a des Arg. The potential to activate complement C3 decreased in sequence of CA, PMMA, PES, PS and PES-SO3. CA activated the most complement C3. PES-SO3 activated the least complement C3, and the concentration of C3a des Arg decreased with the increase in sulphonation degree. The investigation demonstrates that with good biocompatibility PES is a promising material to make biocompatible hemofilters. Furthermore, it indicates that PES containing sulphonate groups can achieve a marked reduction in complement activation and supports the sulphonation as a means of improving the biocompatibility of PES for blood purification application. RIA is a reliable and precise quantitative determination of human C3a des Arg and is suitable for testing the activation of complement of various synthetic materials that are utilized or to be utilized in the medical field.

Complement Activation↗

PubMed2000

A clinical investigation on garlicin injectio for treatment of unstable angina pectoris and its actions on plasma endothelin and blood sugar levels.

To investigate the therapeutic effects and mechanisms of garlicin for treatment of unstable angina pectoris (UAP), garlicin injectio was intravenously dripped 60 mg/day in 34 cases for 10 days. Nitroglycerine was used in 21 cases of the control group. The results showed that the total effective rates in improving symptoms and electrocardiogram after garlicin treatment were respectively 82% and 62%, and that the plasma endothelin and blood sugar levels were markedly lowered in cases with hyperglycemia.

Aged↗

PubMed2000

[Evaluation of performance and blood compatibility of polyethersulfone hollow fiber plasma separator].

In this study, we evaluated the performance and blood compatibility of polyethersulfone hollow fiber membrane plasma separator by animal experiment. Hemolysis did not occur under the usual conditions of plasma separation. The sieving coefficients of total protein, albumin and globulin were over 95%, and about 60% of total plasma were extracted from the whole blood. White blood cells, platelets, fibrinogen, and coagulation factors were decreased during the early stage of plasma separation and appeared to be within acceptable ranges for clinical use.

Animals↗

PubMed2000

[A case-control study on the risk factors of esophageal cancer in Linzhou].

OBJECTIVE: To explore the characteristics of prevalence and influencing factors on the genesis of esophageal cancer. METHODS: A population-based 1:1 matched case-control study was conducted in Linzhou. A total number of 352 pairs of cases and controls matched on sex, age and neighborhoods. Data was analysed by SAS software to calculate the odds ratio of and to evaluate the relative risks. RESULTS: It was found that lower socio-economic status, environmental pollution around the residential areas, lampblack in room, lower body mass index (BMI), more pickled food intake, cigarette smoking, alcoholic drinking, vigor mental-trauma and depression were risk factors of esophageal cancer. It also showed that the subjects having had history of upper digestive tract operation, dysplasia of esophagus and family history of carcinoma markedly increased the risks of developing esophageal cancer. CONCLUSION: Esophageal cancer seemed to be resulted from the combination of genetic and environmental factor, hence called for of medical surveillance and comprehensive prevention.

Adult↗

PubMed2000

[A preliminary study on the incidence of cedar pollinosis in district of Wuhan].

OBJECTIVE: To investigate the incidence of cedar pollinosis in district of Wuhan. METHOD: A survey relative to cedar pollinosis was carried out in 309 students in Hubei Medical University in 1999, including questionnaire investigation, nasal inspection and scratch test. From February to April of 2000, a clinical investigation of cedar pollinosis was adopted among 205 patients of allergic rhinitis including scratch test and nasal mucosa test. RESULT: 1. The positive rate of cedar pollen scratch test of 309 students was 7.8%. 2. 59 cases (28.8%) was hypersensitive to cedar pollen clinically in allergen test. CONCLUSION: Cedar pollinosis is one kind of important pollinosis in district of Wuhan and should be paid high attention to.

Adolescent↗

PubMed2000

[Effects of amiloride on calcium current in thyroxine-induced hypertrophied rat heart].

AIM: The L-Type calcium currents were investigated in normal, hypertrophied and amiloride-treated rat ventricular myocytes so as to clarify the possible cause of the action potential lengthening that has been reported in thyroxine-induced hypertrophy. The interactions between agents such as thyroxine, Ang II and phenylephrine which induced hypertrophy with amiloride on the calcium current were analyzed. METHODS: Myocardial hypertrophy was induced by i.p. L-thyroxine in rats. The cell length, cell width and cell area were measured by image analysis technique. For recording ICaL, the whole cell patch clamp technique was used. Potassium currents were suppressed by replacing K+ ions with Cs+ ions in intracellular media, and sodium current was blocked by 50 mumol.L-1 tetrodotoxin. RESULTS: The Ca2+ current was found to be larger in hypertrophied cells (783pA) than in normal cells (433pA) and in amiloride-treated cells (429pA). However, no significant difference was observed in current density (6.54, 8.33, 5.74 pA/pF) in normal, hypertrophied and amiloride-treated cells. ICa displayed the same voltage dependence in three cell types. The potential giving 50% of activation (V1/2) moved towards more negative and the slope of activation curve was smaller in hypertrophied cells than in normal cells and amiloride cells. When expressed as percentages, the maximal increases in ICa were obtained with 1 mumol.L-1 Ang II and 100 mumol.L-1 phenylephrine in normal cells (+45.5% and +81.8%). Thyroxine 100 mumol.L-1 showed no effect on ICa. After giving amiloride, Ang II and phenylephrine did not increase the amplitude of ICa. CONCLUSION: At the dose of 0.5 mg.kg-1.d-1, amiloride (p.o.) was shown to prevent the amplitude of ICa from increasing and to be effective against increases of amplitude of ICa by Ang II and phenylephrine.

Amiloride↗

PubMed2000

High frequency color Doppler image of choroidal detachment.

PURPOSE: To study the Color Doppler Image (CDI) characteristics of choroidal detachment and the applied value of CDI. METHODS: Seventy-two cases (74 eyes) of choroidal detachment were studied retrospectively. RESULTS: The typical ultragraph of chroridal detachment displayed one or several smooth hemispherical or lobuler circular thick bands, with convex side toward vitreous cavity. Most of the choroidal detachments were located before the equator, a few of them were beyond the equator. CDI displayed blood flow singnal in the band. Pulse Doppler showed the frequency spectrum features of retinal detachment band were similar to those of central retinal vessels, whereas the frequency spectum features of choroidal detachment bend resembled those of ciliary artery in some cases of retinal detachment (RD) accompanied by choroidal detachment. CONCLUSION: CDI could make a correct and precise diagnosis of choroidal detachment.

Adolescent↗

PubMed1999

Ex vivo culture of cord blood CD34+ cells expands progenitor cell numbers, preserves engraftment capacity in nonobese diabetic/severe combined immunodeficient mice, and enhances retroviral transduction efficiency.

Ex vivo culture of hematopoietic stem/progenitor cells could potentially improve the efficacy of human placental/umbilical cord blood (CB) in clinical hematopoietic stem cell (HSC) transplantation and allow gene transduction using conventional retroviral vectors. Therefore, we first examined the effects of a 7-day period of ex vivo culture on the hematopoietic capacity of CB CD34+ cells. Medium for the ex vivo cultures contained either serum and six recombinant human hematopoietic growth factors (GFs), including Flt-3 ligand (FL), Kit ligand (KL = stem cell factor), thrombopoietin (Tpo), interleukin 3 (IL-3), granulocyte colony-stimulating factor (G-CSF), and interleukin 6 (IL-6), or a serum-free medium containing only FL, KL, and Tpo. After culture under both ex vivo conditions, the total numbers of viable cells, CD34+ cells, colony-forming cells (CFCs), and long-term culture initiating cells (LTC-ICs) were increased. In contrast, the severe combined immunodeficiency (SCID) mouse engrafting potential (SEP) of cultured cells was slightly decreased, as compared with fresh cells. Nevertheless, cultured human CB CD34+ cells were able to generate engraftment, shown to persist for up to 20 weeks after transplantation. We next tested the efficacy of retroviral transduction of cultured cells. Transduced cultured human cells were able to engraft in NOD/SCID mice, as tested 4 weeks after transplantation, and EGFP+CD34+ cells and EGFP+ CFCs were isolated from the chimeras. Thus, although additional improvements in ex vivo culture are still needed to expand the numbers and function of human HSCs, the current conditions appear to allow gene transduction into hematopoietic SCID engrafting cells, while at least qualitatively preserving their in vivo engraftment potential.

Animals↗

PubMed1999

Urothelial papilloma of the bladder. Clinical and biologic implications.

BACKGROUND: An international consensus has been reached regarding diagnostic criteria for papilloma of the urinary bladder. However, the incidences of recurrence and progression in patients with urothelial papilloma are uncertain. METHODS: The population for this study consisted of 52 patients who were diagnosed with urothelial papilloma of the bladder at the Mayo Clinic between 1914 and 1998. All histologic slides were reviewed and fulfilled the diagnostic criteria of urothelial papilloma from the 1998 World Health Organization/International Society of Urological Pathology classification system. No patients had previous or coexistent urothelial carcinoma, and none were treated after biopsy. RESULTS: The mean patient age at diagnosis was 57 years (range, 22-89 years). The male-to-female ratio was 1.9:1. The mean follow-up was 9.8 years (range, 0.1-58 years). Four patients developed recurrent papilloma (mean interval from diagnosis to recurrence, 3.3 years); 1 other patient developed papillary neoplasm of low malignant potential (Ta WHO Grade 1 papillary urothelial carcinoma) 6 years after the initial diagnosis of papilloma. None of these patients developed dysplasia, carcinoma in situ, or invasive urothelial carcinoma or died of bladder cancer. CONCLUSIONS: Patients with urothelial papilloma have a low incidence of recurrence and rarely, if ever, develop urothelial carcinoma.

Adult↗

PubMed1999

Papillary urothelial neoplasms of low malignant potential. Clinical and biologic implications.

BACKGROUND: Knowledge of the long term outcomes of patients with papillary urothelial neoplasms of low malignant potential (LMP) is limited. METHODS: The authors studied 112 consecutive patients who were diagnosed with papillary urothelial neoplasms of LMP (formerly Ta, World Health Organization Grade 1 of 3 papillary urothelial carcinoma) at the Mayo Clinic between 1958 and 1963. All histologic slides were reviewed and fulfilled the diagnostic criteria of the 1998 World Health Organization/International Society of Urological Pathology classification system. RESULTS: Patient age at diagnosis ranged from 33 to 99 years (mean, 65 years). The male-to-female ratio was 3:1. The mean follow-up was 12.8 years (range, 0.1-35 years; median, 11.7 years). Twelve patients had biopsy-proven, noninvasive urothelial carcinoma; 17 patients had cystoscopically detected recurrences (all were treated by fulguration without biopsy); and 4 patients developed invasive urothelial carcinoma (including 2 with muscle-invasive carcinoma). Twelve (75%) of 16 patients with biopsy-proven recurrence or progression had cancer dedifferentiation, which resulted in a diagnosis of higher grade cancer than was indicated on initial biopsies. The mean interval from initial diagnosis to development of invasive carcinoma was 13.3 years (range, 10-14 years). Three patients died of bladder cancer. CONCLUSIONS: Patients with papillary urothelial neoplasms of LMP have increased risks of local recurrence, progression, and death from bladder carcinoma. Long term clinical follow-up may be indicated for patient management.

Adult↗

PubMed1999

Correlation of margin status and extraprostatic extension with progression of prostate carcinoma.

BACKGROUND: The correlation of surgical margins and extraprostatic extension (EPE) with progression is uncertain with regard to prostate carcinoma patients treated by radical prostatectomy. The objective of this study was to define factors predictive of cancer progression; emphasis was placed on surgical margins and their relation to extraprostatic extension. METHODS: The study group consisted of 377 patients who were treated by radical retropubic prostatectomy and bilateral pelvic lymphadenectomy at the Mayo Clinic between 1986 and 1993. All specimens were totally embedded and whole-mounted. Patients ranged in age from 41 to 79 years (mean, 65 years). Those with seminal vesicle invasion or lymph node metastasis and those treated preoperatively with radiation or androgen deprivation were excluded. Final pathologic T classifications were pT2a (41 patients), pT2b (237), and pT3a (99). Progression was defined as biochemical failure (prostate specific antigen [PSA] >0.2 ng/mL), clinical or biopsy-proven local recurrence, or distant metastasis. The mean follow-up was 5.8 years (range, 0.2-11.4 years). Seventy-nine patients who received adjuvant treatment within 3 months after surgery were excluded from survival analysis. RESULTS: The overall margin positivity rate was 29%. Seventy-two patients (19%) had only positive surgical margins without evidence of EPE ("surgical incision"), 53 (14%) had only EPE, 37 (10%) had both, and 215 (57%) had neither. Positive margins were correlated with the finding of EPE (P = 0.003). Progression free survival rates at 5 and 10 years were 88% and 67%, respectively. In univariate analysis, preoperative PSA concentration, positive surgical margins, Gleason grade, cancer volume, and DNA ploidy were significant in predicting progression (P values, <0.001, <0.001, 0.01, 0.007, and <0.001, respectively). In multivariate analysis, margin status and DNA ploidy were independent predictors of progression (relative risk for margin status, 1.9; 95% confidence interval [CI], 1.1-3.4; P = 0.03; relative risk for DNA ploidy, 5.1; 95% CI, 2.4-10.9; P<0.001). Among patients with positive margins, 5-year progression free survival was 78% for those with negative EPE and 55% for those with positive EPE. CONCLUSIONS: Surgical margin status and DNA ploidy were independent predictors of progression after radical prostatectomy. To improve cancer control, adjuvant therapy may be considered for patients with positive surgical margins or nondiploid cancer.

Adult↗

PubMed1999

Substaging of T1 bladder carcinoma based on the depth of invasion as measured by micrometer: A new proposal.

BACKGROUND: A significant number of T1 bladder carcinoma patients are understaged by transurethral resection of the bladder (TURB), indicating a substantial need for more accurate staging. METHODS: The authors studied 55 patients with T1 bladder carcinoma detected by TURB at the Mayo Clinic between December 1979 and July 1984. The mean age of the patients was 66 years (range, 50-78 years). All patients were treated by cystectomy. The median interval from TURB to cystectomy was 10 days. Grading was performed according to the 1998 World Health Organization/International Society of Urologic Pathology grading system. The 1997 TNM classification was used for pathologic staging. In addition, the depth of invasion was measured from the mucosal basement membrane by micrometer. Receiver operating characteristic (ROC) analysis was used to evaluate the usefulness of depth of invasion as a marker for advanced stage bladder carcinoma (>/= T2). RESULTS: The final pathologic stages were Ta (2 patients), T1 (10 patients), T2a (9 patients), T2b (13 patients), T3 (11 patients), and T4 (10 patients) at cystectomy. There was a significant correlation between the depth of invasion at TURB and the final pathologic stage (Spearman correlation coefficient = 0.63; P < 0.001). The overall accuracy for the prediction of advanced stage (>/= T2) bladder carcinoma as measured by the area under the ROC curve was 0.89 (standard error, 0.05). Using 1.5 mm as a threshold (with >1.5 mm indicating advanced stage disease), the sensitivity, specificity, and positive and negative predictive values were 81%, 83%, 95%, and 56%, respectively. Histologic grade at the time of TURB also was associated significantly with final pathologic stage at cystectomy (P = 0.03) whereas stratification of patients according to invasion above or below the muscularis mucosae at TURB was not a significant predictor of final pathologic stage. CONCLUSIONS: The results of the current study show that substaging of T1 bladder carcinoma according to the depth of invasion (as measured by micrometer) provides significant prognostic information. Therefore the authors recommend that it be reported in specimens obtained by TURB.

Adult↗