Biomedical subjects
Publications and source records attributed to W Zhang.
Nitric oxide (NO) possesses many physiological effects and S-nitrosothiols have been identified in a variety of tissues exhibiting many NO-like activities. This review focuses on the latest discoveries pertaining to the biological functions of S-nitrosothiols and the recent research progress in the chemical properties and biomedical applications of RSNOs.
Anticancer nucleoside analogs (e.g., ara-C, gemcitabine, fludarabine) induce apoptosis by incorporation into DNA. Removal of incorporated analogs from DNA by 3'-5' exonucleases is presumably a mechanism of drug resistance. Based on our previous observation that the 3'-5' exonuclease activity of wild-type (wt) p53 protein is able to preferentially remove mismatched nucleotides from DNA, in the present study we further investigated the ability of p53 to recognize and remove incorporated therapeutic analogs from DNA and its role in analog-induced apoptosis. We demonstrated that although the 3'-5' exonuclease of wt p53 protein was able to bind and excise the nucleoside analog residues from DNA in vitro, removal of the drug molecules from cellular DNA was slow in whole cells with wt p53 cells, and not detectable in mutant p53 cells. Furthermore, the wt p53 were more sensitive to the cytotoxic effect of the drugs compared to the p53-null or mutant cells. Incubation of ML-1 cells (wt p53) with gemcitabine caused an accumulation of p53 protein in their nuclei and preferentially induced apoptosis in the p53-positive cells, whereas the p53-negative cells remained intact. Transfection of p53-null cells with wt p53 expression vector enhanced the sensitivity of the cells to gemcitabine. Gel mobility shift assay using synthetic DNA containing gemcitabine as the probe suggests that p53 protein is likely to participate in the binding of the analog-containing DNA. Our study suggests that recognition of the incorporated nucleoside analogs in DNA by wt p53 did not confer resistance to the drugs, but it facilitated the apoptotic cell death process.
To evaluate whether overexpression of Bax, an apoptosis-promoting gene, sensitizes KATOIII gastric cancer cells to apoptosis induced by chemotherapeutic agents, three stable cell lines of KATOIII transfected with Bax (KATOIII-Bax), Bcl-2 (KATOIII-Bcl-2), or control pCI-neo expression vector (KATOIII-pCI-neo) were established. The cells were treated with paclitaxel, 5-fluorouracil, or doxorubicin, and the apoptotic response was measured. Our results showed that the sensitivity of the KATOIII-Bax cells to chemotherapeutic agents was enhanced compared with that of the KATOIII-pCI-neo cells, and the KATOIII-Bcl-2 cells were more resistant to these agents. Western blotting revealed that cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was higher than that of the KATOIII-pCI-neo cells. Significant increase of cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was detected 24 h after exposure to chemotherapeutic agents, when apoptotic cells were less than 10%. The cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was higher than that of the KATOIII-pCI-neo cells at all time points examined after exposure to chemotherapeutic agents. Marked activation of caspase-3 in the KATOIII-Bax cells was observed 48 h and 72 h after exposure to chemotherapeutic agents compared with that in the KATOIII-pCI-neo cells. Consistently, zVAD-fmk, a pancaspase inhibitor, repressed the paclitaxel-induced apoptosis. In addition, Bcl-2 overexpression strongly blocked KATOIII cell apoptosis by inhibiting the cytochrome c release from mitochondria and caspase-3 activation. These findings suggest that cytochrome c release is a major mechanism of apoptotic response and Bax overexpression sensitizes KATOIII cells to chemotherapeutic agent-induced apoptosis through enhancing the release of cytochrome c from mitochondria.
Telomerase activation in differentiated cells is associated with cell immortalization. Detection of telomerase expression in cancer provides a potential biomarker to be evaluated in the diagnosis and prognosis of cancer patients. Analysis of telomerase activity in biopsy specimens may serve as a useful marker for the diagnosis of pancreatic adenocarcinoma. This study was conducted to determine if telomerase could be detected in fine needle aspirates from patients with pancreatic carcinoma. The telomeric repeat amplification protocol (TRAP) assay was used to determine telomerase activity from pancreatic cancer cell lines, paired tumor/normal human pancreatic tissues and specimens obtained at the time of diagnostic fine-needle aspiration (FNA) biopsies. In this report, we demonstrate that: i) telomerase activity is present in pathologically confirmed pancreatic cancer specimens, but absent in matched adjacent areas of normal pancreatic tissues; ii) telomerase activity is present in FNA samples obtained at the time of CT-guided FNA of pancreatic adenocarcinomas; and iii) this activity can be detected in material normally discarded during FNA slide preparation. Activation of telomerase can be identified in FNA specimens obtained at the time of routine cytologic diagnosis. These findings may be useful for further diagnostic or therapeutic investigations of telomerase activity in pancreatic carcinoma.
PURPOSE: Although black men with and without prostatic carcinoma in general have higher levels of prostate specific antigen (PSA) than other racial groups, the cause is unknown. Previous studies have shown that black men produce greater PSA per cc of benign gland volume. We determined whether prostatic inflammation varied by race and could account for the racial difference in PSA among prostate cancer patients. MATERIALS AND METHODS: Between April 1993 and February 1997, 238 patients underwent radical prostatectomy for clinically localized prostate cancer at Walter Reed Army Medical Center and whole mounted specimens were processed at the Armed Forces Institute of Pathology. Cases were reviewed by 2 pathologists (W. Z. and I. A. S.) blinded to clinical information, and scored for inflammation as 0--rare; 1--mild, 10 to 15 small foci; 2--moderate, greater than 15 foci with a large area or greater than 20 small foci; 3--marked, greater than 20 small foci with a large area, and 4--diffuse, multiple large areas. The extent of inflammation was correlated to pretreatment PSA and other variables. RESULTS: A total of 181 white and 57 black men were evaluated. Of the patients 28 were excluded from analysis due to prior hormonal therapy. The percentage of patients with inflammation scores from 1 to 4 was higher among white (113 of 161, 70.2%) than black (30 of 49, 61.2%) men but this difference was not significant (p = 0.299) and the extent of inflammation was not significantly related to racial variation in serum PSA. CONCLUSIONS: To our knowledge no significant racial difference exists in the extent of inflammatory infiltrate, and inflammation was not the etiology of the racial difference in serum PSA levels in this clinically localized prostate cancer cohort.
Heart attacks frequently occur in normolipidemic subjects with low concentration of high density lipoproteins (</=35 mg/dL). A low-fat diet is generally recommended to patients with coronary heart disease. A low-fat diet decreases both low density (LDL) and high density lipoproteins (HDL). We have shown that on an Average American Diet, subjects with different HDL-cholesterol (HDL-C) levels have different HDL subpopulation profiles. In low HDL-C subjects (</=35 mg/dL), the apoA-I-only subpopulation alpha(1) is significantly decreased compared to individuals with normal HDL-C levels (>35 mg/dL). We hypothesized that as subjects with low HDL-C already have low HDL concentrations, the major decrease of HDL-C will occur in subjects with normal HDL-C when a low-fat diet is consumed. Normolipidemic male subjects consumed three diets differing in total fat and saturated fat composition (AAD: 37%, Step-1: 28%, Step-2: 24% total fat) for 6 weeks in a three-period double-blind randomized crossover design. Plasma lipids and apolipoproteins were determined and changes in distribution of HDL subpopulations were evaluated. As a result of a low-fat diet, low HDL-C individuals slightly decreased their HDL-C, but substantially decreased their LDL-C resulting in a significant improvement in the LDL-C/HDL-C ratio. However, subjects with normal HDL-C levels decreased both their LDL-C and HDL-C resulting in an unchanged LDL-C/HDL-C ratio. We also observed significant differences in response to low-fat diets in HDL-C and alpha(1) concentrations between low and normal HDL-C subjects. In the normal HDL-C group, consumption of a low-fat diet also resulted in redistribution of apoA-I-containing HDL subpopulations, indicated by a decrease in the large apoA-I-only alpha(1) subpopulation. These data demonstrate that male subjects with low HDL-C respond to a low-fat diet differently than individuals with normal HDL-C.
OBJECTIVE: To introduce a new method for getting human CD14 gene. METHODS: Based on the character of CD14 gene, the authors amplified the CD14 gene directly from genome DNA of human mononuclear cell in peripheral blood by PCR for the first time. RESULTS: A human CD14 gene about 1.1 kb was successfully amplified from genome DNA of human mononuclear cell in peripheral blood, and the sequence analysis has indicated that the CD14 gene cloned in this way is the same as the sequence reported by other authors. CONCLUSION: It is a simple and effective method to obtain human CD14 gene from genome DNA of human mononuclear cell in peripheral blood.
PURPOSE: To study the changes in interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) levels in patients with premature rupture of the membranes (PROM). METHODS: A total of 46 normal term pregnant women served as controls and 46 women with PROM were enrolled for study. Maternal serum and amniotic fluid IL-6, IL-8 and TNF-alpha levels were determined by enzyme-linked immunosorbent assay and a sensitive radioimmunoassay, respectively. RESULTS: The maternal serum IL-6 and IL-8 levels and amniotic fluid IL-6, IL-8 and TNF-alpha levels were higher than those of controls, and the differences were significant between the two groups (p < 0.05). Although the levels of TNF-alpha in maternal serum were higher than that of controls, the difference was not significant. There were significant relationships between the levels of IL-6, IL-8 and TNF-alpha and the duration of PROM. The longer the duration of PROM, the higher the levels of maternal serum and amniotic fluid IL-6, IL-8 and TNF-alpha were. There were 12 cases of clinical chorioamnionitis, and the levels of IL-6, IL-8 and TNF-alpha in the maternal and amniotic fluid were higher than that of those without chorioamnionitis (p < 0.05). CONCLUSION: Determining cytokines (IL-6, IL-8 and TNF-alpha) is a valuable clinical method for identifying chorioamnionitis in patients with PROM.
PURPOSE: To test the hypothesis that after supplemental oxygen recovery (SOR) in the newborn rat model of retinopathy of prematurity (ROP) the preretinal neovascular (NV) incidence and severity are decreased and the panretinal oxygenation ability is improved. METHODS: Newborn rats were first raised in either room air (controls) or variable oxygen (50%/10%) for 14 days. The experimental rats were recovered during the next 6 days (until day 20) in either room air (21% O2) or supplemental oxygen (28%). All groups were then exposed to room air for an additional 6 days (until day 26). On day 20, magnetic resonance imaging (MRI) was used to determine the panretinal oxygenation response (deltaPO2, mm Hg) to a carbogen (95% O2/5% CO2) inhalation challenge. On days 20 and 26, the retinas from a different subset of control, room air-recovered, or SOR-recovered animals were analyzed using ADPase stained or fluorescein-labeled dextran infused retinal flatmounts. RESULTS: On day 20, the panretinal deltaPO2 of the room air-recovered group (125 +/- 5 mm Hg, mean +/- SEM, n = 12) was significantly (P < 0.05) lower than that of the control group (179 +/- 6 mm Hg, n = 11). The panretinal deltaPO2 value for the SOR group (87 +/- 5 mm Hg, n = 7) was significantly (P < 0.05) lower than both the room air-recovered group and the control group. The NV incidence and severity were significantly reduced (P < 0.05) in the SOR animals compared with the room air-recovered animals. In contrast, on day 26 (after 6 days in room air), the NV incidence was statistically (P < 0.05) greater in the animals that had been exposed to SOR compared with room air-recovered animals. CONCLUSIONS: After 28% SOR, the expected decrease in NV incidence and severity occurred but with an unexpected decrease in panretinal oxygenation ability. The present data strongly support an association between subnormal panretinal oxygenation ability and increased NV risk in the newborn rat ROP model. MRI appears to be a powerful new approach for quantitatively and noninvasively measuring retinal oxygenation and may be applicable to study other ischemic or ischemia-related retinopathies in addition to ROP, such as diabetic retinopathy, sickle cell retinopathy, macular degeneration, and glaucoma.
In order to search the possible application of friction pairs of UHMWPE and Ti6Al4V-TiN-TiC etc. gradient materials to total hip joint replacements, we have prepared Ti6Al4V-TiN-TiC etc. gradient film materials by using N ion implant, d. c plasma CVD(PCVD). The properties of biological friction and wear for friction pairs of HUMWPE and Ti6Al4V-TiN-TiC etc. gradient film materials were investigated. The friction coefficient of friction paris and the wear loss of worn UHMWPE were measured; the surface morphology was observed by SEM. It has been shown that in human serum lubrication the wear loss of HUMWPE decreases with the increase in the surface hardness of its pairing ceramic film material. The pairing Ti6Al4V-TiN-TiC gradient film material possesses highest surface hardness, compared with other materials studied; UHMWPE wear loss in lowest. The wear mechanism of studied pairs has been analysed as well in the present paper.
In this paper, we tried to evaluate the effect of water-fat separation on and to optimize the scan condition of the newly developed "Sandwiched" 3-point Dixon method at 0.35 Tesla (T), for knee joint imaging. Using a 0.35T superconductive open magnet system with a solenoid type knee coil, one male and two female normal volunteers (27-37 y.o.) underwent knee joint imaging. Each sequence provided good water-fat separated images. At 0.35T, the gradient echo provided a better contrast than the spin echo. Optimal cartilage-marrow and cartilage-fluid contrast could be obtained at a frip angle (FA) of 90 degrees. There was no significant correlation between cartilage-marrow, cartilage-fluid contrast and repetition time (TR) values within the tested range. Cartilage-fluid and cartilage-marrow contrast were both best at an FA of 90 degrees with the gradient echo sequence. TR from 350 ms to 650 ms did not cause any significant contrast difference in the fat suppressed images. This method is useful and could be the only practical choice for obtaining fat suppressed T1 weighted images for joint magnetic resonance (MR) imaging at 0.35T.
OBJECTIVE: To study the molecular pathological mechanism of the type 2A von Willebrand disease(vWD) and the relationship of the phenotypes with genotypes. METHODS: A total of 126 patients with the hereditary hemorrhagic disease were examined using bleeding time, vWF:Ag, FVIII:CAg, ristocentin induced platelet agglutination assay(RIPA) and multimer analysis of plasma. The exon 28 of authenticity vWF gene was studied by PCR, denaturing gradient gel electrophoresis(DGGE) and sequencing in the type 2A vWD. RESULTS: Fourteen cases were diagnosed as type 2A vWD. Four cases of point mutations resulting in single animo acid substitutions, Arg611His, Ala737Glu, Arg834Trp, were identified in 3 families of type 2A vWD. Ala737Glu substitution in vWF is caused by a novel missense mutation. CONCLUSION: The molecular pathological mechanism of the type 2A vWD is very variant.
OBJECTIVE: To investigate the role of Bcl-2 gene in oncogenesis and progression of non-small cell lung carcinoma(NSCLC). METHODS: The mRNA expressions of Bcl-2 gene in a series of 137 pulmonary tissues collected at various sites and with different properties were studied with Northern hybridization and non-radioactive digoxigenin labeling and detection system. RESULTS: According to the observations on benign lesions, non-cancer tissues distant from tumour, para-tumour tissues and cancer tissues, there was a tendency of mRNA expression increasing of Bcl-2 gene. Among them, Bcl-2 mRNA expression in lung cancer tissues was significantly increased, compared with that in benign lesions and tissues distant from tumour (P<0.01). The Bcl-2 mRNA expression in lymph node with cancer metastasis was significantly higher than that in lymph node without cancer metastasis(P<0.05). The Bcl-2 mRNA expression was relative to cell differentiation of the cancer, but not to the histological classification. CONCLUSION: Over expression of Bcl-2 gene might be involved in the oncogenesis and metastasis of NSCLC.
OBJECTIVE: To investigate the apoptosis induced by adenovirus-mediated transduction of human genes (p53, B(7-1), GM-GSF, IL-2) in liver cancer cells and the effects of tumorigenicity in nude mice. METHODS: Using light microscopy and electron microscopy and TUNEL assay, apoptosis in Ad-multigenes-transduced liver cancer cell lines was detected. The tumorigenicity of HepG(2) cells transduced with Ad-multigenes was detected. RESULTS: Ad-multigenes could induce apoptosis, and elevated sensitivity of human liver cancer cells to chemotherapy drugs. After cells with transduced Ad-multigenes were treated with 10mg/L cisplatin for 24 h, apoptosis was seen in nearly 30% of them. The tumorigenicity of Ad-multigenes-transduced was reduced. CONCLUSION: Apoptosis induced by adenovirus-mediated multigenes acts synergetically with cisplatin in promotion of inducing apoptosis in liver cancer cell lines.
OBJECTIVES: Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error. Recent data based upon whole-mounted step-sectioned radical prostatectomy specimens using a 3-D computer assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. A new 10-core biopsy pattern was shown to be superior to the traditional sextant biopsy. This pattern includes the traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland. The objective of this study is to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in a small cohort of patients. METHODS: We retrospectively reviewed 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. RESULTS: Of the 35 patients diagnosed with prostate cancer, 54.3% (19/35) were diagnosed when reviewing the sextant biopsy data only. Review of the 10-core pattern revealed that an additional 45.7% (16/35) of patients were diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. CONCLUSIONS: Our results suggest that biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Lateral biopsies in the apex and mid portion of the gland are the most important.
Transrectal Ultrasonography (TRUS) based systematic needle biopsy of the prostate has been widely used clinically in the diagnosis of prostate carcinoma. Current protocols for prostate biopsy, such as the Sextant Protocol, however, have been proven to be insufficient in cancer detection since these protocols were built without having accurate information on 3D distribution of prostate cancers. In this research, our goal is to optimize prostate biopsy protocols by statistically investigating spatial distributions of prostate cancers. Based on the low-resolution nature of ultrasound imaging and the current clinical conventions, we propose to divide each individual prostate gland into different zones that are can be recognized and accessed by the urologists with ultrasound images during biopsy. By calculating cancer appearance inside each of these zones using a large number of prostate samples, we get the overall distributions of prostate cancers based on which an optimal biopsy protocol can be developed.
BACKGROUND: Organochlorine compounds, including organochlorine pesticides, have been suggested by some, but not all, studies to be associated with female breast-cancer risk. So far, studies relating organochlorine compounds and breast-cancer risk have mainly focused on polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) as risk factors for female breast cancer. This paper examines the hypothesis that environmental exposure to trans-nonachlor (TNC) and oxychlordane (OCD), a major metabolite of the insecticide chlordane, increases the METHODS: A total of 304 histologically confirmed, incident primary breast-cancer patients and 186 histologically confirmed incident benign breast-disease controls were included in the study between 1994 and 1997. Breast adipose tissue not needed for diagnostic purposes was collected and analysed for TNC, OCD and other organochlorine compounds. A standardised, structured questionnaire was used to obtain information on major known, or suspected, risk factors for breast cancer. RESULTS: The age and lipid-adjusted geometric mean adipose-tissue levels of OCD were similar between the cases [36.4 p.p.b., 95% confidence interval (CI) 34.7-38.2 p.p.b.] and controls (38.0 p.p.b., 95% Cl 35.7-40.6 p.p.b.). The age and lipid-adjusted geometric mean adipose-tissue levels of TNC between the cases (55.5 p.p.b., 95% CI 52.6-58.5 p.p.b.) and controls (58.1 p.p.b., 95% CI 54.2-62.3 p.p.b.) were also similar. There was no association between breast-cancer risk and mean adipose-tissue levels of OCD and TNC. The covariate-adjusted odds ratio (OR) was 0.7 (95% CI 0.4-1.3) for OCD and 1.1 (95% CI 0.6-1.9) for TNC, when the highest quartile was compared with the lowest. The risk also did not vary based on oestrogen or progesterone receptor status or menopausal status. DISCUSSION: We found no significantly increased risk of breast cancer associated with breast adipose-tissue levels of OCD or TNC; this is consistent with recent epidemiological studies, indicating that environmental exposure to organochlorine compounds does not have an overall significant impact on breast-cancer risk.
Two patients (from the same family) with a bleeding disorder were diagnosed with type 2A von Willebrand disease (vWD). The 28th exon of the von Willebrand factor (vWF) gene was obtained by polymerase chain reaction and then screened by denaturing gradient gel electrophoresis. The fragments displaying abnormal melting behavior were directly sequenced. A heterozygous C-->A substitution changing alanine 1500 to glutamic acid at position 4750 in the A2 domain of vWF was found. The structure of recombinant A1500E vWF within transfected COS-7 cells and the secretion of high-molecular-weight (HMW) multimers were similar to wild-type vWF. HMW forms of vWF multimers were absent in plasma but present in platelets. The mutation described here corresponds to the group II type 2A vWD characterized by normal secretion of all vWF multimers.