Biomedical subjects

D E Williams

Publications and source records attributed to D E Williams.

At least 91 records · Page 5Linked to original sources

PubMed1997

Neutrophil maturation of CD34+ cells from peripheral blood and bone marrow in serum-free culture medium with PIXY321 and granulocyte-colony stimulating factor (G-CSF).

Bone marrow (BM) or peripheral blood (PB) CD34+ cells were cultured for 12 days in serum-free culture medium containing PIXY321 (IL-3/ GM-CSF fusion protein) with or without periodic supplements of granulocyte-colony stimulating factor (G-CSF). The cultures were evaluated at day 12 for total cell proliferation (fold increase from day 0), neutrophil differentiation by flow cytometry, using dual staining with CD15-FITC and CD11b-PE, and morphology using Wright-Giemsa and granule staining. In cultures containing PIXY321 where 6000 U/ml of G-CSF was added days 0 and 6, there was no significant difference (p > or = 0.05) in cell proliferation or the percent of CD15+/CD11b+ cells when compared with cultures with PIXY321 alone. ELISA analysis showed G-CSF levels had declined by 90% after 3 days of culture. Further studies were performed to assess the benefit of supplementing lower concentrations of G-CSF (600 U/ml) at more frequent intervals. A significant increase (p < or = 0.05) in cell proliferation and percent CD15+/CD11b+ was observed when G-CSF was added on days 0, 3, 6, and 9 (every 3 days) as compared with those cultures with PIXY321 alone. CD34+ cell proliferation without G-CSF was 19.6 +/- 4.8-fold, with G-CSF added on days 0 and 6 was 28.7 +/- 6.4-fold, and with G-CSF added on days 0, 3, 6, and 9 was 45.9 +/- 10.6-fold. Percent of CD15+/CD11b+ cells was 19.0 +/- 4.6%, 38.2 +/- 7.2%, and 58.5 +/- 6.5%, respectively, in these cultures. We observed more CD15+/CD11b+ cells, myelocytes/metamyelocytes, and secondary granule staining in cultures with G-CSF added on day, 0, 3, 6, and 9 as compared with cultures with G-CSF added on days 0 and 6 or no G-CSF added. We conclude that PIXY321 and G-CSF act synergistically on the in vitro proliferation and neutrophil differentiation of BM and PB CD34+ cells and that frequent supplements of G-CSF facilitate neutrophil differentiation.

Adult↗

PubMed1997

Inhibition of 2-amino-3-methylimidazo[4,5-f]quinoline-DNA adducts by indole-3-carbinol: dose-response studies in the rat colon.

Indole-3-carbinol (I3C) inhibits the formation of colonic aberrant crypt foci and DNA adducts in rats given heterocyclic amine colon carcinogens, such as 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Mechanism studies indicate that I3C induces cytochromes P4501A1 and 1A2 (CYP1A1 and CYP1A2), isozymes that respectively metabolize IQ via ring hydroxylation or activate the carcinogen by N-hydroxylation. The present study examined the dose-response for induction of CYP1A1 versus CYP1A2 by I3C, and compared the profiles of induction with the dose-response for inhibition of IQ-DNA adducts in the colon of the F344 rat. Dietary equivalent doses of I3C in the range 100-1000 p.p.m. increased in a dose-related manner both ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities in the liver and colonic mucosa, and Western blots showed a corresponding induction of CYP1A1 and CYP1A2 proteins. However, dietary equivalent doses of I3C in the range 10-25 p.p.m. (i) reduced hepatic EROD and MROD activities and CYP1A protein levels compared with controls, (ii) increased the ratio of CYP1A2 versus CYP1A1, and (iii) activated IQ to a more potent mutagen when liver microsomes from rats given I3C were used for metabolic activation in the Salmonella assay. Rats given a single oral dose of I3C shortly before administering IQ (5 mg/kg body wt, p.o.) exhibited dose-related inhibition of colonic IQ-DNA adducts in the range 25-100 p.p.m. I3C, reaching 95% inhibition at doses > or = 100 p.p.m. I3C, but IQ-DNA adducts were elevated slightly at the lowest I3C dose as compared with the controls. The possible significance of the low versus high dose effects of I3C are discussed in the context of human dietary exposures to I3C and the reported chemopreventive mechanisms of I3C in vivo.

Animals↗

PubMed1997

Psychiatric consultations in stiff-man syndrome.

BACKGROUND: Stiff-man syndrome is a rare central nervous system disease first described nearly 40 years ago. Its cause has been attributed to both neurologic and psychiatric processes. In recent years, it has been accepted as a neurologic condition in which the gamma-aminobutyric acid (GABA) system malfunctions, probably because of an autoimmune process. Published reports that have described psychiatric manifestations of the disease have relied on descriptions of one or two cases and literature reviews. METHOD: We reviewed the medical records of 24 patients with confirmed stiff-man syndrome, 12 of whom had received psychiatric consultation. This review was done to better determine the psychiatric manifestations of stiff-man syndrome. RESULTS: Retrospective analysis of these 12 cases showed that the most common psychiatric symptoms were anxiety, depression, and alcohol abuse. CONCLUSION: We speculate that the GABA system is involved in both the neurologic and psychiatric symptoms of these patients. Psychiatrists have a significant role in the management of patients with stiff-man syndrome and may be expected to manage anxiety, depression, and substance misuse.

Adult↗

PubMed1996

The c-kit ligand potentiates the allogeneic mixed lymphocyte reaction.

The allogeneic mixed lymphocyte reaction (MLR) is a complex in vitro assay of T-cell recognition and responsiveness in which interleukin-2 (IL-2) plays a central role. We have previously demonstrated that c-kit ligand (KL) can enhance IL-2-induced proliferation in a subset of human natural killer cells expressing the c-kit tyrosine kinase receptor. In the present study, we asked whether KL could enhance IL-2-mediated T-cell proliferation in the allogeneic MLR. We demonstrate that the vast majority of activated human T-cell clones express the c-kit mRNA transcript. Binding studies performed on activated T cells with radioiodinated KL were consistent with the expression of a single class of c-kit receptors. The addition of exogenous KL to the MLR led to an increase in tritiated thymidine (3[H]-TdR) incorporation in the absence of other exogenous cytokines, and did so in a dose-dependent fashion. A reproducible increase in 3[H]-TdR incorporation was noted at concentrations of KL, which approximate those normally found in vivo. Antibody blocking of KL binding to c-kit, T-cell depletion and sorting experiments suggest that the action of KL is mediated at least in part by a direct effect on both CD4+ and CD8+ T-cells. KL's enhancement of the MLR also requires the binding of IL-2 to its high-affinity IL-2 receptor. Given the abundance of KL normally found in human serum, these data suggest that this cytokine may have a role during T-cell activation in vivo.

Animals↗

PubMed1996

Identification of human juvenile chronic myelogenous leukemia stem cells capable of initiating the disease in primary and secondary SCID mice.

Most juvenile chronic myelogenous leukemia (JCML) cells have limited long-term proliferative capacity, and only a minority of immature cells give rise to colonies in semisolid cultures. Clonogenic JCML progenitors cannot be maintained in culture because they differentiate, and within a few weeks the leukemic clone is lost. This makes it difficult to identify the cell that initiates and maintains the disease in patients. To determine the proliferative capacity of JCML cells in vivo, bone marrow (BM), peripheral blood, or spleen cells from eight patients with JCML either at diagnosis or during treatment were transplanted into sublethally irradiated severe combined immune deficient (SCID) mice. JCML cells from all patients homed to the murine BM and proliferated extensively in response to exogenous stimulation with granulocyte-macrophage colony-stimulating factor. Within a few weeks, highly engrafted mice became ill and cachectic due to infiltration of leukemic cells and secretion of tumor necrosis factor-alpha. Murine BM, spleen, and liver were infiltrated with leukemic blasts, and typical JCML colony-forming progenitors could be recovered. Kinetic experiments demonstrated that only a small minority of transplanted cells homed to the murine BM, and that these cells initiated and maintained the disease in vivo by extensive proliferation and differentiation. To characterize the cell-surface phenotype of the JCML initiating cell (JCML-IC), JCML blood or spleen cells were fractionated on the basis of CD34/CD38 marker expression and transplanted into SCID mice. Only immature CD34+ cells could initiate the disease, while mature CD34- cells did not engraft. Within the CD34+ compartment, there was enrichment for JCML-ICs by immature cells with a CD34+/CD38- stem-cell-like phenotype. Mice transplanted with more mature CD34+/CD38+ populations that also contained clonogenic JCML progenitors were poorly engrafted. These results indicate that the JCML-IC is an earlier stage of development than clonogenic JCML progenitors. Additional evidence that the JCML-IC has stem-cell properties comes from secondary transplant experiments that test the self-renewal capacity. The JCML-IC from all three patients tested could successfully reinitiate the disease in secondary murine recipients. Thus, we have developed a functional in vivo model that replicates many aspects of human JCML, and have used this model to identify and characterize JCML-ICs and their stem-cell properties.

Animals↗

PubMed1996

Hematologic effects of flt3 ligand in vivo in mice.

We have investigated the effects of in vivo treatment with flt3 ligand (FL) on murine hematopoiesis, including mobilization of progenitors into the peripheral blood (PB). Mice were injected once daily with 10 micrograms recombinant human FL for 15 days. On days 3, 5, 8, 10, 15, and 22, mice were killed and analyzed for the number of leukocytes and colony-forming units (CFU) in bone marrow (BM), spleen, and PB. Splenic and PB cellularity increased with time in FL-treated mice. In the spleen, there was an increase in B cells, myeloid cells, and nucleated erythroid cells; in the PB, there was an increase in lymphocytes, granulocytes, and monocytic cells. The maximal number of CFU in the BM was observed after 3 days of FL treatment, giving 3.7- and 7.3-fold increases in CFU-granulocyte-macrophage (CFU-GM) and CFU-granulocyte, erythrocyte, monocyte, megakaryocyte (CFU-GEMM), respectively, compared with mouse serum albumin (MSA)-treated controls. After 8 days of FL treatment, there was a maximal 123- and 108-fold increase in splenic CFU-GM and CFU-GEMM, respectively. The maximal number CFU-GM and CFU-GEMM were seen in PB on day 10, with 537- and 585-fold increases, respectively. Burst-forming units-erythroid (BFU-E) increased in the same time frame as those of CFU-GM and CFU-GEMM in BM, spleen, and PB, although the magnitude was not as great. Primitive day-13 CFU-spleen (CFU-S) and phenotypically defined stem cells were also mobilized into the PB of FL-treated mice with similar kinetics and magnitude to that of CFU-GM and CFU-GEMM. We conclude from these studies that FL, when administered as a single agent, is a potent mobilizer of hematopoietic progenitors into the PB.

Animals↗

PubMed1996

Selection and expansion of peripheral blood CD34+ cells in autologous stem cell transplantation for breast cancer.

Cytopenia after high-dose chemotherapy and autologous stem cell reinfusion is a major cause of morbidity. Ex vivo cultured expansion and differentiation of CD34+ peripheral blood progenitor cells (PBPC) to neutrophil precursors may shorten the neutropenic period further. We explored the use of these ex vivo cultured PBPCs in nine patients with metastatic breast cancer. All underwent PBPC mobilization with cyclophosphamide, VP-16, and G-CSF. Subsequently, they underwent four to five apheresis procedures. One apheresis product from each patient was prepared using the Isolex 300 Magnetic Cell Separation System (Baxter Immunotherapy, Irvine, CA) to obtain CD34+ cells. These cells were then cultured in gas permeable bags containing serum-free X-VIVO 10 (BioWhittaker, Walkersville, MD) medium supplemented with 1% human serum albumin and 100 ng/mL PIXY321. At day 12 of culture the mean fold expansion was 26x with a range of 6 to 64x. One patient's cells did not expand because of a technical difficulty. The final cell product contained an average of 29.3% CD15+ neutrophil precursors with a range of 18.5% to 48.1%. The patients underwent high-dose chemotherapy with cyclophosphamide, carboplatin, and thiotepa. On day 0, the cryopreserved PBPCs were reinfused and on day +1 the 12-day cultured cells were washed, resuspended, and reinfused into eight of nine patients. One patient was not infused with cultured cells. The mean number of cultured cells reinfused was 44.6 x 10(6) cells/kg with a range of 0.8 to 156.6 x 10(6) cells/kg. No toxicity was observed after reinfusion. The eight patients have recovered absolute neutrophil counts > 500/microL on a median of 8 days (range 8 to 10 days); the median platelet transfusion independence occurred on day 10 (range 8 to 12 days) and platelet counts > 50,000/microL were achieved by day 12 (range 9 to 14) for the seven patients whose platelet counts could be determined. Expanded CD34+ selected PBPC can be obtained and safely reinfused into patients.

Adult↗

PubMed1996

The human homologue of rat NG2, a chondroitin sulfate proteoglycan, is not expressed on the cell surface of normal hematopoietic cells but is expressed by acute myeloid leukemia blasts from poor-prognosis patients with abnormalities of chromosome band 11q23.

In our efforts to produce monoclonal antibodies that recognize cell-surface antigens expressed by hematopoietic precursor and stromal cells, we generated a monoclonal antibody, 7.1, which recognizes a 220- to 240-kD cell-surface protein whose N-terminal amino acid sequence is identical to the rat NG2 chondroitin sulfate proteoglycan molecule. This chondroitin sulfate proteoglycan, previously reported to be expressed by human melanoma cells, was not found to be expressed by normal hematopoietic cells, nor was it expressed on the cell surface of cell lines of hematopoietic origin including cell lines with 11q23 abnormalities. It was found on the cell surface of acute myeloid leukemia (AML) blasts and cell lines derived from nonhematopoietic tissues. Samples of leukemic marrow from 166 children with AML enrolled on Childrens Cancer Group protocol 213 were evaluated for cell-surface expression of this proteoglycan molecule. In 18 of 166 (11%) patient samples, greater than 25% of leukemic blasts expressed the NG2 molecule. These 18 patients had a poorer outcome with respect to survival (P = .002) and event-free survival (P = .035) with an actuarial survival at 4 years of 16.7%. Blast cell expression of the NG2 molecule was strongly associated with French-American-British M5 morphology (P < .0001) and abnormalities in chromosome band 11q23, site of the MLL gene. These results show that the NG2 molecule is expressed by malignant hematopoietic cells that have abnormalities in chromosome band 11q23, suggesting that antibody 7.1 may be useful in the rapid identification of this group of poor-prognosis patients.

Actuarial Analysis↗

PubMed1996

Characterization of thymic stromal-derived lymphopoietin (TSLP) in murine B cell development in vitro.

B cell development is dependent on both direct interactions with stromal cells and their secreted cytokines. The precise mechanisms by which these interactions regulate B cell differentiation are currently unknown. We report here that a novel growth factor thymic stromal-derived lymphopoietin (TSLP) can replace the activity of interleukin-7 (IL-7) in supporting B cell development in vitro. TSLP was found to promote the proliferation and differentiation of committed B220+ B cell progenitors from day 15 fetal liver. Phenotypic analysis of these cells revealed that they are at the pro-B cell stage of differentiation and express cell surface markers characteristic of pro-B cells cultured in IL-7. TSLP can replace the activity of IL-7 in supporting the progression of B lymphocytes from uncommitted bipotential precursors. In the absence of either TSLP or IL-7, the progeny of cells that give rise to mature B lymphocytes fail to develop from these bipotential precursors. Moreover, TSLP can substitute for IL-7 in supporting the sustained proliferative response exhibited by B cell progenitors from CBA/N mice. Together these results show that TSLP can replace the requirement for IL-7 during in vitro B cell development.

Animals↗

PubMed1996

Comparison of the enhancing effects of dehydroepiandrosterone with the structural analog 16 alpha-fluoro-5-androsten-17-one on aflatoxin B1 hepatocarcinogenesis in rainbow trout.

Dehydroepiandrosterone (DHEA) is an adrenal steroid with chemoprotective effects against a wide variety of conditions including cancer, obesity, diabetes, and cardiovascular disease. However, DHEA is also a carcinogen in laboratory animals, possibly through its function as a precursor of sex steroids or peroxisome proliferation. The structural analog 16 alpha-fluoro-5-androsten-17-one (8354) has been reported to have enhanced chemopreventive activity without the steroid precursor and peroxisome proliferating effects of DHEA. This study compares DHEA and 8354 in rainbow trout, a species that is resistant to peroxisome proliferation but is highly susceptible to the carcinogenic and tumor enhancing effects of DHEA. Trout were exposed as fry to aflatoxin B1 (AFB1) or given a sham exposure, then were fed diets containing 444 ppm DHEA or 8354 for 6 months. Postinitiation treatment with DHEA significantly increased liver tumor incidence, multiplicity, and size compared to initiated controls. The analog 8354 slightly increased tumor incidence (p = 0.06) but had no effect on multiplicity or size. Six percent of trout treated with DHEA alone developed tumors, whereas no tumors occurred in noninitiated trout fed control or 8354-containing diets. Serum levels of androstenedione were elevated by DHEA (48-fold) or 8354 (6-fold) treatment. Serum beta-estradiol titers were increased in DHEA- but not 8354-treated trout. Vitellogenin was induced significantly by either DHEA (434-fold) or 8354 (21-fold). Peroxisomal beta-oxidation was not increased by either compound and catalase activity was decreased in DHEA-treated animals. Both steroids were potent inhibitors in vitro of trout liver glucose-6-phosphate dehydrogenase with IC50s of 24 and 0.5 microM for DHEA and 8354, respectively. This research suggests that in trout the tumor enhancing effects of DHEA may be due to its function as a sex steroid precursor and are unrelated to peroxisome proliferation. These carcinogenic properties are reduced in the analog 8354 which has been advocated as an alternative to DHEA for chemoprevention.

Aflatoxin B1↗

PubMed1996

Modulation of N-methyl-N'-nitro-nitrosoguanidine multiorgan carcinogenesis by dehydroepiandrosterone in rainbow trout.

Dehydroepiandrosterone (DHEA) and its sulfate conjugate are the major circulating steroids in human plasma. Low levels of these adrenal steroids are associated with a number of human diseases including certain cancers. In animal studies, DHEA is chemopreventive toward both spontaneous and chemically induced cancers. A potential concern for long-term usage of DHEA in humans is the finding that DHEA is hepatocarcinogenic in rats. The human health risk has been thought to be minimal, however, as the mechanism of DHEA hepatocarcinogenesis is assumed to be due to its properties as a peroxisome proliferator, a class of compounds to which humans are relatively insensitive. Recently, we have found DHEA to be a potent promoter of aflatoxin B1-initiation as well as a complete hepatocarcinogen in the rainbow trout, a species which is also insensitive to peroxisome proliferators. In order to determine the initiator- and tissue-specificity of DHEA promotion, we examined the effects of DHEA on N-methyl-N'-nitro-nitrosoguanidine (MNNG)-initiated carcinogenesis. Trout fry were initiated by a bath exposure (30 min at 35 ppm) to MNNG and then fed DHEA at levels of 0, 55, 111, 222, 444, or 888 ppm for 7 months. DHEA increased liver tumor incidence, multiplicity, and size in a dose-dependent manner. The liver tumor incidence ranged from 0 in the MNNG-initiated controls to 99% in initiated trout fed 888 ppm DHEA. The latter represents a potential synergistic interaction in liver between MNNG and DHEA, as tumor incidence in sham-initiated trout fed this level of DHEA was 41%. The kidney tumor incidence was also enhanced two- and threefold over initiated controls by 111 and 888 ppm DHEA, respectively. In contrast, the total number of stomach and swim bladder tumors was reduced by DHEA treatment. This study demonstrates differential effects of DHEA on MNNG-initiated carcinogenesis in liver, kidney, stomach, and swim bladder.

Animals↗

PubMed1996

A prospective psychological evaluation of patients with dysphagia of various etiologies.

We hypothesized that patients who complain of dysphagia without demonstrable organic abnormality may have an underlying psychological dysfunction. We thus conducted a comprehensive assessment in three groups of patients with dysphagia. Dysphagia was classified as obstructive (Obst) when an obstructive lesion was present on esophagoscopy or barium swallow, motility-related (Mot) when abnormal motility was shown on esophageal manometry in the presence of normal esophagoscopy or barium swallow, or nonobstructive, nonmotility-related (NONM) when manometry and esophagoscopy or barium swallow were both normal. We prospectively evaluated 71 patients with Obst-dysphagia, 15 patients with Mot-dysphagia and 10 patients with NONM-dysphagia with a battery of standardized psychological tests including the Minnesota Multiphasic Personality Inventory (MMPI), the Symptom Checklist-90-Revised (SCL-90-R), and the Millon Behavioral Health Inventory (MBHI). The results indicate that patients with NONM-dysphagia have psychological attributes similar to those found in patients with Obst-dysphagia or Mot-dysphagia. Combination of scores for parameters such as somatization, depression, and anxiety could not distinguish among the three groups of dysphagia patients. We thus conclude that patients with NONM-dysphagia, as a group, have similar psychological profiles compared to patients with dysphagia due to organic causes.

Adult↗

PubMed1996

Cytokine production by a megakaryocytic cell line.

The regulation of megakaryopoeisis by cytokines is not yet well understood. It is possible that autocrine loops are established during megakaryocyte growth and differentiation, aiding in the maturation of these cells. The CHRF-288-11 human megakaryoblastic cell line has been examined for cytokine production in growing cells and cells stimulated to differentiate by the addition of phorbol esters. It has been demonstrated that these cells produce RNA corresponding to the interleukins IL-1 alpha, 1 beta, 3, 7, 8, and 11, granulocyte-macrophage colony stimulating factor (GM-CSF), stem cell factor (SCF), transforming growth factor-beta (TGF-beta), tumor necrosis factor-alpha (TNF-alpha), interferon-alpha (INF-alpha), and basic fibroblast growth factor (bFGF). Additionally, RNA corresponding to the receptors for IL-6, GM-CSF, SCF, INF-alpha, beta, bFGF, and monocyte colony stimulating factor (M-CSF) were also expressed by the cells. The receptor for TNF-alpha was detected immunologically. Analysis at the protein level demonstrated that significant amounts of INF-alpha, TNF-alpha, GM-CSF, SCF, IL-1 alpha, and a soluble form of the IL-6 receptor were produced by the cells. Addition of phorbol esters to CHRF-288-11 cells enhances their megakaryocytic phenotype; such treatment also results in increased secretion of INF-alpha, TNF-alpha, and GM-CSF. These results suggest that potential autocrine loops are established during the differentiation of CHRF-288-11 cells, which may alter the capability of the cell to differentiate. These findings are similar to those recently obtained for marrow-derived megakaryocytes (Jiang et al.) suggesting that CHRF-288-11 cells provide a useful model system for the study of cytokine release during megakaryocyte differentiation.

Cell Line↗

PubMed1996

The model Ah-receptor agonist beta-naphthoflavone inhibits aflatoxin B1-DNA binding in vivo in rainbow trout at dietary levels that do not induce CYP1A enzymes.

beta-Naphthoflavone (BNF), a well-known Ah-receptor agonist, has been believed to inhibit aflatoxin B1 (AFB1) carcinogenesis in rats and rainbow trout primarily through induction of the cytochrome P450 1A (CYP1A) enzyme subfamily and consequent diversion of AFB1 to the less carcinogenic phase I metabolite aflatoxin M1 (AFM1). This study investigates the dose responsive effects of dietary BNF treatment on CYP1A induction. AFM1 formation, AFB1-8,9-epoxide formation and AFB1-DNA binding in the trout model. Pre-feeding diet containing 10-200 p.p.m. BNF after AFB1 i.p. injection provided dose-dependent induction of CYP1A-dependent ethoxyresorufin-O-deethylase (EROD) activity and inhibition of in vivo AFB1-DNA binding. However, most of the observable inhibition of DNA adduction (45% inhibition) had occurred at 10 p.p.m. BNF without detectable EROD induction; higher doses of BNF up to 200 p.p.m. induced EROD > 6-fold but provided only another 15% inhibition of DNA adduction in vivo. When in vitro AFB1-DNA binding was assessed using liver microsomes from trout fed 10-100 p.p.m. BNF, induced microsomal EROD activity correlated moderately with reduction of in vitro AFB1-DNA binding activity. However, BNF treatment in a low dose range (0.2-10 p.p.m.) also strongly inhibited in vivo hepatic AFB1-DNA binding (69% inhibition at 5 p.p.m. BNF in this experiment), in a dose-dependent manner, in the complete absence of detectable EROD induction. The microsomes from 5 p.p.m. BNF-treated trout had no more EROD activity than control microsomes, and no less capacity for catalyzing AFB1-DNA binding in vitro than control microsomes. Thus, the potent inhibition of hepatic AFB1-DNA binding in vivo by 5 p.p.m. BNF was a result of neither CYP1A enzyme induction nor irreversibly reduced catalytic capacity for AFB1-8,9-epoxide formation. Direct analysis of AFB1 metabolites formed in vitro by liver microsomes from trout fed 10, 100 and 500 p.p.m. BNF showed that low dietary BNF (10 p.p.m.) neither induced microsomal CYP1A-mediated AFM1 formation nor altered AFB1-8,9-epoxide formation compared to the control. By comparison, 100 and 500 p.p.m. BNF pretreatment significantly elevated microsome-catalyzed AFM1 formation in vitro (P < 0.001), and this increase was highly correlated with increased EROD activity (r2 = 0.999, P < 0.001). Upon in vitro addition, BNF was found to be a potent inhibitor of microsome-mediated AFB1-8,9-exo-epoxide formation (IC50 = 2.6 +/- 0.1 microM) and AFB1-DNA binding (inhibition constant Ki = 3.03 +/- 0.25 microM). These findings indicate that CYP1A enzyme induction can contribute modestly to BNF protection against AFB1 in this species both in vivo and in vitro at higher BNF doses, but does not do so at lower doses. Instead, enzyme inhibition by BNF against AFB1 8,9-epoxidation appears to be the predominant protective mechanism at higher BNF doses, and the sole protective mechanism at low doses, in the rainbow trout. These findings demonstrate that mechanisms of chemoprevention can change with anticarcinogen dose, and caution that even potent induction of phase I or phase II activities does not assure that pathway to be a predominant protective mechanism in vivo.

Aflatoxin B1↗

PubMed1996

Prostate specific antigen and androgen receptor induction and characterization of an immortalized adult human prostatic epithelial cell line.

Progress in prostate cancer research has been hindered by the lack of well characterized, immortalized, human prostatic epithelial cell lines that express markers of normal prostatic epithelial cells and mimic normal growth and differentiation responses to androgens. The objectives of this study were to: (i) establish immortalized cell lines from non-neoplastic, adult human prostatic epithelium using adenovirus-12/simian virus-40 (Ad12-SV40) hybrid virus; (ii) establish their prostatic epithelial origin; (iii) demonstrate androgen responsiveness; and (iv) examine response to growth factors. Primary epithelial cell cultures derived from a non-neoplastic, adult human prostate were infected with the Ad12-SV40 virus. Several immortalized clones were isolated. Single cell cloning of one clone, free of cytopathic effects, gave rise to the PWr-1E cell line. An immortalized cell line PWR-1E, which expresses many characteristics of normal prostatic epithelial cells was established. Immunostaining showed that cells express cytokeratins 8 and 18 normally expressed by differentiated, secretory prostatic epithelial cells. The most remarkable characteristics of PWR-1E cells are growth stimulation, increased expression of androgen receptor and induction of prostate specific antigen (PSA) expression in response to androgens, which indisputably establish their prostatic epithelial origin. They are positive for SV40 large-T antigen and show strong nuclear staining for p53. Cells from passages 23 and 40 were not tumorigenic in nude mice even when co-injected with Matrigel. They grow in a serum-free defined medium and respond to EGF, bFGF and TGF-beta. Passage 42-cells showed a human male (XY), hyperdiploid karyotype. The PWR-1E cell line is the only known Ad12-SV40-immortalized human prostatic epithelial cell line. PWR-1E cells can be used to study (i) the etiology and the multistep process of carcinogenesis and tumor progression in the human prostate; (ii) normal prostate physiology and differentiation; and (iii) potential prostate cancer chemopreventive agents.

Androgens↗

PubMed1996

Professionals' perceptions of psychotropic medication in residential facilities for individuals with mental retardation.

Professional staff in four state facilities for individuals with mental retardation were surveyed to determine their perceptions, knowledge and opinions regarding the use of psychotropic medication. A large majority of the 377 respondents indicated that the physicians in their facilities were primarily responsible for medication-related decisions. Under ideal conditions, however, all professional staff and parents were seen as having a greater influence in the decision-making process. Aggression, delusions and hallucinations, self-injury, other psychiatric disorders, and anxiety were rated as disorders most likely to result in medication therapy. Behaviour modification was viewed as a suitable alternative to drug treatment for acting out and aggression. The professionals indicated that behavioural observation was the most influential assessment technique in current usage, followed by global impressions and informal diaries. Over 80% of the respondents perceived their preservice and inservice training on issues related to the use of psychotropic medication to treat behaviour problems as inadequate, with 96% of them desiring continuing education. These findings were compared to data from similar studies of populations with other disabilities, and suggestions for modifications in the current decision-making processes related to the use of psychotropic medication in institutionalized individuals with mental retardation are discussed.

Adolescent↗

PubMed1996

Fish models for environmental carcinogenesis: the rainbow trout.

Progress over the past 30 years has revealed many strengths of the rainbow trout as an alternative model for environmental carcinogenesis research. These include low rearing costs, an early life-stage ultrasensitive bioassay, sensitivity to many classes of carcinogen, a well-described tumor pathology, responsiveness to tumor promoters and inhibitors, and a mechanistically informative nonmammalian comparative status. Low-cost husbandry, for example, has permitted statistically challenging tumor study designs with up to 10,000 trout to investigate the quantitative interrelationships among carcinogen dose, anticarcinogen dose, DNA adduct formation, and final tumor outcome. The basic elements of the trout carcinogen bioassay include multiple exposure routes, carcinogen response, husbandry requirements, and pathology. The principal known neoplasms occur in liver (mixed hepatocellular/cholangiocellular adenoma and carcinoma, hepatocellular carcinoma), kidney (nephroblastoma), swim bladder (adenopapilloma), and stomach (adenopapilloma). Trout possess a complex but incompletely characterized array of cytochromes P450, transferases, and other enzymic systems for phase I and phase II procarcinogen metabolism. In general, trout exhibit only limited capacity for DNA repair, especially for removal of bulky DNA adducts. This factor, together with a high capacity for P450 bioactivation and negligible glutathione transferase-mediated detoxication of the epoxide, accounts for the exceptional sensitivity of trout to aflatoxin B1 carcinogenesis. At the gene level, all trout tumors except nephroblastoma exhibit variable and often high incidences of oncogenic Ki-ras gene mutations. Mutations in the trout p53 tumor suppressor gene have yet to be described. There are many aspects of the trout model, especially the lack of complete organ homology, that limit its application as a surrogate for human cancer research. Within these limitations, however, it is apparent that trout and other fish models can serve as highly useful adjuncts to conventional rodent models in the study of environmental carcinogenesis and its modulation. For some problems, fish models can provide wholly unique approaches.

Animals↗

PubMed1996

Prospective evaluation of the utility of molecular techniques for diagnosing nosocomial transmission of multidrug-resistant tuberculosis.

OBJECTIVE: To compare molecular techniques with conventional diagnostic methods for evaluating nosocomial transmission of multidrug-resistant tuberculosis (MDR-TB). DESIGN: We conducted a 12-week postexposure inception cohort study of health-care personnel who had been exposed to a patient with MDR-TB. MATERIAL AND METHODS: In addition to baseline and follow-up tuberculin skin tests and chest roentgenography, weekly pulmonary specimens were evaluated by (1) auramine-rhodamine fluorescent staining, (2) culture for mycobacteria, and (3) polymerase chain reaction (PCR) to amplify IS6110, a nucleic acid insertion sequence unique to the Mycobactrium tuberculosis complex. RESULTS: The index patient's isolate of M. tuberculosis showed a mutation in codon 531 of the RNA polymerase beta subunit (rpoB) gene of M. tuberculosis, which is associated with rifampin resistance and considered a marker for this MDR-TB strain. All pulmonary and gastric specimens from study participants had negative auramine stains and cultures for mycobacteria, One person, however, had separate specimens with repeatedly positive PCR results for IS6110 sequences, but the specimens contained a wild-type M. tuberculosis rpoB codon 531 dissimilar from the index patient's strain. CONCLUSION: Although both molecular and conventional testing showed that no exposed person was infected with the MDR-TB strain, molecular test results were available sooner and seemed more sensitive for detecting M. tuberculosis in one exposed person, presumably in a preinfection or "colonized" stage. Molecular methods provided information that helped distinguish this person's M. tuberculosis strain from the index patient's MDR-TB strain. Additional prospective studies should assess the value of these molecular techniques in similar clinical settings.

Antitubercular Agents↗