Multidrug resistant gram-negative bacilli as predominant bacteremic pathogens in liver transplant recipients

BACKGROUND

Bacteremias, which are often caused by gram-negative bacteria, are the most frequently occurring infectious complications after liver transplantation (LT). The aim of this study was to investigate bacteremic incidence, pathogenic spectrum, risk factors for bacteremia due to multidrug resistant (MDR) gram-negative bacilli, and its impact on mortality after LT.

METHODS

A cohort analysis of prospectively recorded data was done in 475 LT recipients, who were divided into 3 categories: cases with gram-negative bacteremia, cases with MDR gram-negative bacteremia, and cases without bacteremia as controls.

RESULTS

In 475 LT recipients, there were 152 (32.0%) patients with gram-negative bacillus bacteremia in the first 6 months after LT. Out of 152 patients, there were 225 bacteremic episodes, which accounted for 69.7% in a total 323 bacteremic episodes. A total of 190 bacteremic episodes were caused by Stenotrophomonas maltophilia, Enterobacteriaceae, Ochrobactrum anthropi, Pseudomonas, and Acinetobacter baumanii, all of which were the most frequent gram-negative isolates in this study, and MDR bacilli constituted 56.3%. The most frequent source was intravascular catheters. There were 70 patients with MDR gram-negative bacillus bacteremia. Independent risk factors for bacteremia due to MDR gram-negative bacillus were as follows: post-LT abdominal infection (P<0.0001, odds ratio [OR] 0.066, 95% confidence interval [CI] 0.019-0.226), post-LT reoperative episodes (P<0.0001, OR 10.505, 95% CI 3.055-36.121), or one or more episodes of acute rejection (P=0.042, OR 4.457, 95% CI 0.988-20.103). In the first 6 months after LT, MDR gram-negative bacillus bacteremia-related mortality was significantly higher than that due to antibiotic-susceptible bacillus (38.6% vs. 14.6%, P<0.001).

CONCLUSION

Post-LT bacteremias caused by MDR gram-negative bacilli are common, and associated with allograft acute rejection, post-LT reoperation, and abdominal infection. The increasing isolates of MDR gram-negative bacilli pose a great challenge for clinical treatment.

Siderophore production by the marine-derived Aureobasidium pullulans and its antimicrobial activity

Over 300 yeast strains isolated from different marine environments were screened for their ability to produce siderophore. Among them, only the yeast strain HN6.2 which was identified to be Aureobasidium pullulans was found to produce high level of the siderophore. Under the optimal conditions, this yeast strain could produce 1.1mg/ml of the siderophore. The crude siderophore produced by the yeast strain HN6.2 was able to inhibit cell growth of Vibrio anguillarum and Vibrio parahaemolyticus, isolated from the diseased marine animals.

[Effects of exogenous Ca2+ on leaf photosynthetic apparatus and active oxygen scavenging enzyme system of chrysanthemum under high temperature stress]

Taking cut flower chrysanthemum 'Jinba' as test material, the effects of exogenous Ca2+ on its photosynthetic system and antioxidant enzyme activities under high temperature stress were investigated, with the possible action mechanisms of Ca2+ discussed. The results showed that under high temperature stress, Ca2+ addition greatly inhibited the net photosynthesis rate (P(n)) and quantum yield of PS II electron transport (phi(PS II)). After 24 h treatment, the P(n) and psi(PS II) were increased by 31.11% and 21.88% , respectively, and the initial fluorescence (F(o)) decreased by 13.19%, compare with the control. Ca2+ addition also greatly enhanced the activities of SOD, POD and CAT, and thus, the active oxygen was scavenged timely. After 24 h treatment, the MDA accumulation and REC were 29.20% and 35.81% lower than the control, respectively. In conclusion, Ca2+ addition could efficiently protect chrysanthemum leaves from the damage in photosynthetic apparatus under short-term high temperature stress.

Birth of twins after in vitro fertilization with flow-cytometric sorted buffalo (Bubalus bubalis) sperm

Flow-cytometric sorting of mammalian sperm for production of offspring with the desired sex is one of the most important new biotechnologies available for livestock industry. The objectives of this study were: (i) to sort the sperm into X- and Y-enriched populations and (ii) use the sorted sperm for in vitro fertilization (IVF) to produce sex-preselected embryo and offspring. The results revealed that the accuracy of sorted X- and Y-sperm was 94% and 89%, respectively. There was a decrease in blastocyst development rate in IVF with sorted sperm comparing to unsorted sperm, but the percentage of blastocysts on D6-D8 was not statistically different. Transplantation of the presumed X-embryos derived from IVF into a recipient resulted in the birth of female twins. These results indicated the feasibility of sperm sorting by flow cytometry and in vitro production of sex-preselected embryos and offspring in buffalo.

[Identification and cell phenotype transdifferentiation of adipose-derived stem cells]

OBJECTIVE

To investigate the transdifferentiation of the ADSCs to epidermal cells.

METHODS

ADSCs were isolated and cultured from rat adipose tissue by digestion of enzyme. ADSCs was identified by immunocytochemistry and flow cytometry. ADSCs were divided into four groups in order to induce: the condition medium (containing 30% superior of homogenizing rat skin in 10% FBS/DMEM) group, 7 days; 10% FBS/DMEM with EGF (20 ng/ml) group, 7 days; the condition medium for 4 days and then 10% FBS/DEME instead of the condition medium for 3 days group; 10% FBS/DMEM for 7 days group (control group). Cytokeratin 19 and cytokeratin 10 expressions in ADSCs were detected by flow cytometry.

RESULTS

(1) The results of immunocytochemistry showed that ADSCs were positive for CD49d and negative for CD106, CD34, CD19, CD10. The results of flow cytometry showed ADSCs were positive for CD49d and CD44. (2) The CK19 expression of ADSCs was 45.32% in the condition medium group, 26.58% in the condition medium with EGF group, 23.37% in te condition medium for 4 days and then 10% FBS/DMEM instead of the condition medium for 3 days gropu and 18.53% in control group, P <0.01. The CK10 expression of ADSCs was 43.56% in the condition medium group, 25.54% in the condition medium with EGF group, 18.20% in the condition medium for 4 days and then 10% FBS/DMEM instead of the condition medium for 3 days group and 2.46% in control group, P < 0.01.

CONCLUSIONS

The superior of homogenizing rat skin can induce CK19 and CK10 expressing in ADSCs, and thereby demonstrating ADSCs can differentiate to epidermal cell phenotype in vitro.

Field emission of GaN-filled carbon nanotubes: high and stable emission current

Field electron emission of GaN-filled carbon nanotubes, grown by microwave plasma enhanced chemical vapor deposition, was investigated. The detailed structural characterization shows that the filled nanotube has a GaN-core/C-shell structure, in which the GaN wire corresponds to a wurtzite structure. The field emission properties of the GaN-filled carbon nanotubes have been achieved with high and stable emission current. It is attributed to the unique cable-like structure, which makes the GaN-core/C-shell composite mechanically solid and chemically stable. This study suggests the GaN-filled carbon nanotube as an ideal candidate for future high-current and high-power field emitter applications.

[Research on the association between different levels of serum iron and essential hypertension]

OBJECTIVE

To study the relationship between serum iron(SI) and essential hypertension (EHT) based on population-based samples.

METHODS

Using clustering multistage sampling method, all the people above 18 years old in the target population were investigated. Blood pressure was measured and the questionnaire was used to find out related factors. Five milliliters fast vein blood were drawn and the serum were used for testing on serum iron (SI) and other elements such as blood sugar, cholesterol (CHOL), triglyceride (TG), high density lipoprotein(HDL-C), low density lipoprotein (LDL-C), serum sodium, serum potassium, serum calcium etc. A case control study was carried out with EHT patients from the selected population as case group, and the other healthy peoples as controls. Database was created by Fox Pro and SPSS 10.0 was used for statistical analysis.

RESULTS

The concentrations of SI, with (17.75 +/- 7.66) micromol/ L in EHT group and (17.23 +/- 7.83) micromol/L in control group, showed statistical difference (P < 0.05) between the two groups. The concentrations of SI also showed statistical difference (P < 0.05) between the high DBP and normal group with the average level as (17.84 +/- 7.58) micromol/L in high DBP group and (17.26 +/- 7.85) micromol/L in normal group. Data from monovariate analysis showed that the increase of SI was a risk factor for EHT, DBP and SBP. By multivariate analysis for EHT, while SI still existed in the model (OR = 1.296, 95% CI: 1.057-1.590), but for SBP the results almost remained the same (OR = 1.285, 95% CI:1.102-1.498).

CONCLUSION

Data from the results showed that SI was probably a risk factor for EHT.

Direct Synthesis of B−C−N Single-Walled Nanotubes by Bias-Assisted Hot Filament Chemical Vapor Deposition

Direct synthesis of large-scale ternary boron carbonitride single-walled nanotubes (BCN-SWNTs) via a bias-assisted HFCVD process was presented. The BCN-SWNTs were grown over the powdery Fe-Mo/MgO catalyst by using CH4, B2H6, and ethylenediamine vapor as the reactant gases. As high as 16 atom % nitrogen can be incorporated within the nanotube shells, with the boron content in the range of 2-4 atom %. The ternary covalent bonding nature of the BCN-SWNTs was well characterized, and the B, C, and N elemental maps were clearly imaged by energy-filtered transmission electron microscopy.

Protein function classification via support vector machine approach

Support vector machine (SVM) is introduced as a method for the classification of proteins into functionally distinguished classes. Studies are conducted on a number of protein classes including RNA-binding proteins; protein homodimers, proteins responsible for drug absorption, proteins involved in drug distribution and excretion, and drug metabolizing enzymes. Testing accuracy for the classification of these protein classes is found to be in the range of 84-96%. This suggests the usefulness of SVM in the classification of protein functional classes and its potential application in protein function prediction.

Kinetics of acetyl coenzyme A: arylamine N-acetyltransferase from rapid and slow acetylator human benign prostatic hyperplasia tissues

N-acetyltransferase (NAT) activity was determined in 40 human benign prostatic hyperplasia tissues using 2-aminofluorene (AF) and p-aminobenzoic acid (PABA) as substrates. These were then assayed by high performance liquid chromatography for determining the amounts of acetylated AF and PABA and non-acetylated AF and PABA. The activities (mean +/- SD) of AF-NAT from human benign prostatic hyperplasia tissues were divided into rapid (2.06 +/- 0.08 nmol/min per milligram protein), intermediate (1.25 +/- 0.26 nmol/min per milligram protein), and slow (0.58 +/- 0.30 nmol/min per milligram protein) acetylator groups. The activities (mean +/- SD) of PABA-NAT from human benign prostatic hyperplasia tissues were also divided into rapid (2.00 +/- 0.00 nmol/min per milligram protein), intermediate (1.25 +/- 0.18 nmol/min per milligram protein), and slow (0.48 +/- 0.29 nmol/min per milligram protein) acetylator groups. Kinetic constants for arylamine NAT activities were determined for each of these acetylator groups. Apparent differences in Km and Vmax for AF were found. Therefore, there seems to be a polymorphism in NAT activity with two rapid, five intermediate, and 33 slow acetylators among the 40 samples assayed. This is the first demonstration of acetyl CoA-arylamine NAT activity in human benign prostatic hyperplasia tissues.

Expression of nuclear factor-kappa B in hepatocellular carcinoma and its relation with the X protein of hepatitis B virus

AIM

In this study we investigated the relationship of the X protein of HBV and nuclear factor-kappa B (NF-kappa B) and the expression of NF-kappa B in human hepatocellular carcinoma tissues.

METHODS

Immunohistochemistry SP method was used to detect the expression of NF-kappa B and the X protein of HBV in human hepatocellular carcinoma tissues of 52 cases. Gene transfection mediated by lipofectamine was used to transfect the eukaryotic expression vector pCDNA3.1-HBX of HBV x gene into human hepatocellular carcinoma cell line HCC-9204 and NF-kappa B was detected.

RESULTS

NF kappa B was widely expressed in human hepatocellular carcinoma tissues in a total of 52 cases and its expression was related to the X protein of HBV. NF-kappa B was localized both in the cytoplasm and the nuclei of hepatocellular carcinoma cells in 11 cases which were positive for the X protein of HBV while in 41 cases negative for the X protein of HBV, NF-kappa B was only localized in the cytoplasm of hepatocellular carcinoma cells but translocated to the nuclei of hepatocellular carcinoma cells after the eukaryotic expression vector pCDNA3.1-HBX was transfected into HCC-9204 cells.

CONCLUSION

This study strongly suggests that the nuclear factor NF-kappa B is widely expressed in hepatocellular carcinoma tissues in different styles according to the expression of the X protein of HBV. NF-kappa B is abnormally activated in hepatocellular carcinoma, which is probably related to the X protein of HBV. The X protein of HBV can activate NF-kappa B to translocate into nuclei of hepatocellular carcinoma cells.

Mitogen-stimulated TIS21 protein interacts with a protein-kinase-Calpha-binding protein rPICK1

TIS21 is induced transiently by PMA and a number of extracellular stimuli. Yeast two-hybrid screening has identified three TIS21 interacting clones from a rat cDNA library [Lin, Gary, Yang, Clarke and Herschman (1996) J. Biol. Chem 271, 15034-15044]. The amino acid sequence deduced from clone 5A shows 96.9% identity with the murine PICK1, a protein kinase Calpha (PKCalpha)-binding protein postulated to act as an intracellular receptor for PKC. A fusion protein of glutathione S-transferase and rPICK1 associates with the TIS21 translated in vitro, suggesting a direct physical interaction between these two proteins. TIS21 and rPICK1 are co-immunoprecipitated from NIH 3T3 cells overexpressing these two proteins. This indicates that the interaction also occurs in mammalian cells. Deletion of the PDZ domain at the N-terminus of rPICK1 abolishes its interaction with TIS21. A putative carboxylate-binding loop required for PICK1 to bind PKCalpha [Staudinger, Lu and Olson (1997) J. Biol. Chem 272, 32019-32024] is within this deleted region. Our results suggest a potential competition between TIS21 and PKC for binding to PICK1. We show that recombinant TIS21 is phosphorylated by PKC in vitro. The catalytic activity of PKC towards TIS21 is significantly decreased in the presence of rPICK1, whereas phosphorylation of histone by PKC is not affected. rPICK1 seems to modulate the phosphorylation of TIS21 through specific interactions between these two proteins. TIS21 might have a role in PKC-mediated extracellular signal transduction through its interaction with rPICK1.

Inducible overexpression of Bak sensitizes HCC-9204 cells to apoptosis induced by doxorubicin

AIM

To investigate the role of overexpression of Bak in apoptotic pathways and drug susceptibility using doxorubicin and vinorelbine in human HCC-9204 cells.

METHODS

An inducible system, MT-II regulatory system which allowed controlled expression of protein upon addition of ZnSO4(100 mumol/L) as an external inducer was used. Stable transfection of pMD-Bak gene was performed on HCC-9204 cells. Apoptotic cells were measured by morphological criteria, as well as by TUNEL assay and flow cytometry. The ability of Bak to decrease clonogenic cell survival was studied by colony-forming assays, while decrease in cell viability was assessed by MTT assay.

RESULTS

Cells overexpressing Bak showed extensive cell death with nucleus fragmentation detected by TUNEL assay. FACS analyses showed that Bak could induce significant G1 accumulation and apoptosis in 19.29% cells 24 h after induction. Bak significantly decreased the clonogenic survival following exposure to adriamycin, but not vinorelbine. Furthermore, the time-course of cell viability rates following exposure of HCC-9204/Bak cells to adriamycin and vinorelbine was in agreement with the above findings. Bak selectively sensitized HCC-9204 cells to death induced by adriamycin while resisted to vinorelbine.

CONCLUSION

Bak may prolong cell cycle in G1 phase, leading to apoptosis and decrease clonogenic survival of HCC-9204 cells in a drug-specific manner.

Growth inhibition and modulation of kinase pathways of small cell lung cancer cell lines by the novel tyrosine kinase inhibitor STI 571

Small cell lung cancer (SCLC) is an aggressive cancer characterized by several autocrine growth mechanisms including stem cell factor and its receptor c-Kit. In order to arrive at potentially new and novel therapy for SCLC, we have investigated the effects of the tyrosine kinase inhibitor, STI 571, on SCLC cell lines. It has been previously reported that STI 571 does not only inhibit cellular Abl tyrosine kinase activity but also the PDGF receptor and c-Kit tyrosine kinases at similar concentrations (approximately 0.1 microM). There is no expression of the PDGF-receptor, and the Abl kinase is not activated by SCLC, but over 70% of SCLC contain the c-Kit receptor. Utilizing this preliminary data, we have determined that three (NCI-H69, NCI-H146 and NCI-H209) of five (including NCI-H82 and NCI-H249) SCLC cell lines had detectable c-Kit receptors and were inhibited in growth and viability at concentrations 1 - 5 microM of STI 571 after 48 h of treatment. The SCLC cell lines, NCI-H69, NCI-H146 and NCI-H209, showed a dose-response (tested between 0.1 - 10 microM) inhibition of tyrosine phosphorylation of c-Kit as well as in vitro kinase activity (at 5 microM) of c-Kit in response to STI 571. STI 571 inhibited cell motility, as assessed by time-lapsed video microscopy, within 6 h of STI 571 treatment (5 microM). STI 571 also decreased intracellular levels of reactive oxygen species (ROS) by at least 60%, at a concentration (5 microM) that also inhibited cell growth. Cell cycle analysis of STI 571 responsive cells showed that cells were generally slowed in G2/M phase, but there was no arrest at G1/S. A downstream phosphorylation target of c-Kit, Akt, was not phosphorylated in response to stem cell factor in the presence of STI 571. These data imply that STI 571 inhibits growth of SCLC cells through a mechanism that involves inactivation of the tyrosine kinase c-Kit. The effectiveness of STI 571 in this study suggests this drug may be useful in a clinical trial, for patients with SCLC. Oncogene (2000) 19, 3521 - 3528

Ecdysteroid hormones and metabolites of the stone crab, Menippe mercenaria

The Y-organs of the xanthid crab Menippe mercenaria secrete the ecdysteroids, 3-dehydroecdysone (3DE) and lesser amounts of 3-dehydro (or 2-dehydro)-25-deoxyecdysone (3D25dE) in vitro. These ecdysteroids were identified by elution-time comparisons with authentic standards, mass spectrography, and, for 3D25dE, infrared spectrometry. Tissues were incubated 18 hr with [(3)H]3DE. Activities representing 3beta-reductase and 20-hydroxylase generally were present, evidenced by finding in the tissue/medium extract labeled ecdysone (E) and 20-hydroxyecdysone (20E). Labeled 3-dehydro-20-hydroxyecdysone (3D20E) also appeared to be present. Tissue blanks and hemolymph were devoid of activity. Muscle was low, hypodermis was intermediate, and hindgut and gonads were high in activity of the enzymes. Consistent with the presence of these enzymes in peripheral tissues, ecdysteroid products identified in the hemolymph were 20E, 3D20E, and 25-deoxy-20-hydroxyecdysone (25d20E; ponasterone A). Structures of 20E and 3D20E were confirmed by co-elution with authentic standards in high-performance liquid chromatography (HPLC), co-elution of derivatives in gas chromatography, and mass spectroscopy. Ponasterone A (identified by HPLC co-elution with the standard), like 20E is present in the hemolymph in prominent amounts. These data indicate that Menippe, among crustaceans thus far studied, secretes a unique combination of ecdysteroid hormones, namely, a 3- (or 2-) oxo compound and a 25-deoxy compound. This represents a different kind of branch point from 5beta-diketol in ecdysteroid biosynthesis, in which the intermediate, 5beta-ketodiol is bypassed. A result is the joint appearance in the circulation of the hormones, 20E and ponasterone A, which in other species are singly prominent.

Intracerebral hemorrhage after liver transplantation

We report 5 patients with intracerebral hemorrhage after orthotopic liver transplantation (OLT) and identify the possible risk factors. Between November 1991 and April 1999, 75 adult patients received 77 orthotopic liver transplants at Queen Mary Hospital, Hong Kong. Five patients (6.5%) developed intracerebral hemorrhage postoperatively. Clinical and laboratory data were reviewed, and potential risk factors were analyzed. The 5 patients developed intracerebral hemorrhage within 40 days (range, 1 to 37 days; median, 4 days) after OLT. The mortality rate was 80% (4 of 5 patients). The intraoperative blood transfusion volume (median, 17,200 mL; range, 15,750 to 30,360 mL) administered to patients who developed intracerebral hemorrhage postoperatively was significantly greater than that (median, 6,990 mL; range, 1,840 to 22,680 mL) for patients without the complication (P =.0008). Massive intraoperative transfusion (>15,000 mL) was required in all 5 patients (100%) with intracerebral hemorrhage but only 9 of 72 patients (12.5%) in the other group (P =.0001). Four of 5 patients (80%) with intracerebral hemorrhage had intraoperative hypotension compared with 7 of 72 patients (9.7%) in the other group (P =.001). No significant difference was found in age, prothrombin time (PT), activated partial thromboplastin time (APTT), incidence of hypertension, bleeding at extracerebral sites, cyclosporine A neurotoxicity, thrombocytopenia, hemodialysis, and sepsis between the patients with and without intracerebral bleeding. However, the median cumulative score of coagulation parameters (PT, APTT, platelet count) was significantly greater in the group with than without intracerebral bleeding (median score, 3 v 1; P =.023). Intracerebral hemorrhage is 1 of the most disastrous complications after OLT. Intraoperative hypotension, massive intraoperative transfusion, and coagulopathy may be correlated with this complication.

Increased ventricular repolarization inhomogeneity during postural changes in patients with syndrome X

The interlead variation in QT interval (QT dispersion) can be used to assess regional inhomogeneity of ventricular repolarization under a variety of conditions, including stress. Patients with syndrome X may have increased sympathetic activity that could change QT interval regionally and give rise to an increase in QT dispersion under exercise testing. To test the hypothesis, 26 consecutive patients with syndrome X (group 1) were studied. Two additional groups matched in terms of age, sex, and left ventricular mass index consisting of 26 nonconsecutive patients with coronary artery disease (group 2) and 20 normal subjects (group 3) were studied for comparison. Standing induced a significantly higher increase of heart rate in group 1 than in groups 2 and 3 (7.5+/-6.0 vs 4.0+/-6.3 and 1.1+/-3.6 beats/min; p = 0.05 and 0.003, respectively). There were significant differences in QT dispersion between groups 1 and 2 on upright standing (48+/-12 vs 34+/-14 ms, p = 0.0003), but not at baseline (33+/-14 vs 38+/-11 ms, p = NS) or at peak exercise (38+/-9 vs 38+/-9 ms, p = NS). Results did not change when QTc dispersion was substituted for QT dispersion. From a conditional multivariate logistic regression analysis, the only independent predictor of occurrence of syndrome X on upright standing was QTc dispersion (odds ratio = 1.255, p = 0.01). Electrocardiographic QTc dispersion provides important clinical information. Patients with syndrome X had a higher increase of heart rate and QTc dispersion in response to standing from the supine position compared with patients with coronary artery disease and normal subjects.

Cytosine deaminase adenoviral vector and 5-fluorocytosine selectively reduce breast cancer cells 1 million-fold when they contaminate hematopoietic cells: a potential purging method for autologous transplantation

Ad.CMV-CD is a replication incompetent adenoviral vector carrying a cytomegalovirus (CMV)-driven transcription unit of the cytosine deaminase (CD) gene. The CD transcription unit in this vector catalyzes the deamination of the nontoxic pro-drug, 5-fluorocytosine (5-FC), thus converting it to the cytotoxic drug 5-fluorouracil (5-FU). This adenoviral vector prodrug activation system has been proposed for use in selectively sensitizing breast cancer cells, which may contaminate collections of autologous stem cells products from breast cancer patients, to the toxic effects of 5-FC, without damaging the reconstitutive capability of the normal hematopoietic cells. This system could conceivably kill even the nondividing breast cancer cells, because the levels of 5-FU generated by this system are 10 to 30 times that associated with systemic administration of 5-FU. The incorporation of 5-FU into mRNA at these high levels is sufficient to disrupt mRNA processing and protein synthesis so that even nondividing cells die of protein starvation. To test if the CD adenoviral vector sensitizes breast cancer cells to 5-FC, we exposed primary explants of normal human mammary epithelial cells (HMECs) and the established breast cancer cell (BCC) lines MCF-7 and MDA-MB-453 to the Ad.CMV-CD for 90 minutes. This produced a 100-fold sensitization of these epithelial cells to the effects of 48 hours of exposure to 5-FC. We next tested the selectivity of this system for BCC. When peripheral blood mononuclear cells (PBMCs), collected from cancer patients during the recovery phase from conventional dose chemotherapy-induced myelosuppression, were exposed to the Ad.CMV-CD for 90 minutes in serum-free conditions, little or no detectable conversion of 5-FC into 5-FU was seen even after 48 hours of exposure to high doses of 5-FC. In contrast, 70% of 5-FC was converted into the cytotoxic agent 5-FU when MCF-7 breast cancer cells (BCCs) were exposed to the same Ad.CMV-CD vector followed by 5-FC for 48 hours. All of the BCC lines tested were shown to be sensitive to infection by adenoviral vectors when exposed to a recombinant adenoviral vector containing the reporter gene betagalactosidase (Ad.CMV-betagal). In contrast, less than 1% of the CD34-selected cells and their more immature subsets, such as the CD34+CD38- or CD34(+)CD33- subpopulations, were positive for infection by the Ad.CMV-betagal vector, as judged by fluorescence-activated cell sorting (FACS) analysis, when exposed to the adenoviral vector under conditions that did not commit the early hematopoietic precursor cells to maturation. When artificial mixtures of hematopoietic cells and BCCs were exposed for 90 minutes to the Ad.CMV-CD vector and to 5-FC for 10 days or more, a greater than 1 million fold reduction in the number of BCCs, as measured by colony-limiting dilution assays, was observed. To test if the conditions were damaging for the hematopoietic reconstituting cells, marrow cells collected from 5-FU-treated male donor mice were incubated with the cytosine deaminase adenoviral vector and then exposed to 5-FC either for 4 days in vitro before transplantation or for 14 days immediately after transplantation in vivo. There was no significant decrease in the reconstituting capability of the male marrow cells, as measured by their persistence in female irradiated recipients for up to 6 months after transplantation. These observations suggest that adenovirus-mediated gene transfer of the Escherichia coli cytosine deaminase gene followed by exposure to the nontoxic pro-drug 5-FC may be a potential strategy to selectively reduce the level of contaminating BCCs in collections of hematopoietic cells used for autografts in breast cancer patients.

Mechanism of inhibition of MDA-MB-468 breast cancer cell growth by 2,3,7,8-tetrachlorodibenzo-p-dioxin

Treatment of estrogen receptor (ER)-negative MDA-MB-468 human breast cancer cells with 10 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced formation of a nuclear aryl hydrocarbon (Ah) receptor complex as determined by ligand-binding and gel electrophoretic mobility shift assays. TCDD also induced CYP1A1-dependent activity in MDA-MB-468 cells, which represents the first ER-negative Ah receptor-positive human breast cancer cell line that has been identified. Treatment of this cell line with TCDD and related compounds also caused a 50% inhibition of cell growth, which resembled the growth inhibitory effects previously reported for epidermal growth factor (EGF). However, EGF expression is minimal in this cell line and is not induced by TCDD; moreover, EGF and TCDD induced a different pattern of oncogene expression and apoptosis in MDA-MB-468 cells. In contrast, TCDD caused a rapid and sustained induction of transforming growth factor alpha (TGF alpha) gene expression and secreted protein (nearly 2-fold); moreover, the growth-inhibitory effects of TCDD could be blocked by antibodies to the EGF receptor. In a separate experiment, it was shown that TGF alpha also inhibited growth of MDA-MB-468 cells. The results of this study indicate that the mechanism of growth inhibition of MDA-MB-468 cells by TCDD is due to induction of TGF alpha, which is a potent antimitogen in this cell breast cancer line.

Simultaneous team approach of a crown-lengthening procedure and an operative restoration: technique and long-term effect

Traditionally, crown-lengthening procedures to expose subgingival caries for operative restorative work are carried out in a two-stage approach. A disadvantage of this procedure is that the gingival margin associated with the treated tooth moves apically; this may create an esthetic problem. Resin-modified glass-ionomer cement has been demonstrated to have good biocompatibility with dental hard and soft tissues. Surgical and restorative procedures were combined at the same appointment in an effort to achieve a restoration with minimal change in the gingival margin. Four patients have been treated with this one-stage team approach and followed for 8 to 13 months. The clinical results demonstrated this team approach procedure is excellent for the dentition when esthetics is a consideration.