Associations of lead biomarkers with renal function in Korean lead workers

AIMS

To compare associations of lead biomarkers with renal function in current and former lead workers.

METHODS

Cross sectional analysis of first year results from a longitudinal study of 803 lead workers and 135 controls in South Korea. Clinical renal function was assessed by blood urea nitrogen (BUN), serum creatinine, and measured and calculated creatinine clearance. Urinary N-acetyl-beta-D-glucosaminidase (NAG) and retinol-binding protein were also measured.

RESULTS

Mean (SD) tibia lead, blood lead, and DMSA chelatable lead levels in lead workers were 37.2 (40.4) micro g/g bone mineral, 32.0 (15.0) micro g/dl, and 767.8 (862.1) micro g/g creatinine, respectively. Higher lead measures were associated with worse renal function in 16/42 models. When influential outliers were removed, higher lead measures remained associated with worse renal function in nine models. An additional five associations were in the opposite direction. Effect modification by age was observed. In 3/16 models, associations between higher lead measures and worse clinical renal function in participants in the oldest age tertile were significantly different from associations in those in the youngest age tertile which were in the opposite direction. Mean urinary cadmium (CdU) was 1.1 micro g/g creatinine (n = 191). Higher CdU levels were associated with higher NAG.

CONCLUSIONS

These data suggest that lead has an adverse effect on renal function in the moderate dose range, particularly in older workers. Associations between higher lead measures and lower BUN and serum creatinine and higher creatinine clearances may represent lead induced hyperfiltration. Environmental cadmium may also have an adverse renal impact, at least on NAG.

Does solvent influence the ground-state tautomeric population of hypericin?

Nuclear magnetic resonance measurements indicate that hypericin exists in the same "normal" tautomeric form irrespective of whether the solvent is dimethyl sulfoxide or tetrahydrofuran. This result is discussed in the context of previous experimental and theoretical work. It is concluded that solvent perturbations cannot induce tautomerization in hypericin.

Determination of carbohydrate contents from excess light scattering

In the light scattering technique, glycosylation gives rise to excess light scattering for glycoproteins. Assuming additivity of refractive index and using an appropriate refractive index increment for carbohydrate, one can determine the degree of glycosylation from the excess light scattering. Here we have used size-exclusion chromatography in combination with online light scattering, UV absorbance, and refractive index. The results show that the technique accurately determines the carbohydrate content of recombinant stem cell factor.

8-oxo-dGTPase, which prevents oxidative stress-induced DNA damage, increases in the mitochondria from failing hearts

BACKGROUND

Reactive oxygen species (ROS) can cause an oxidative modification of nucleotides, such as 8-oxo-7,8-dihydrodeoxyguanosine triphosphate (8-oxo-dGTP), which can lead to defects in DNA replication. The misincorporation of 8-oxo-dGTP into DNA is prevented by 8-oxo-dGTPase, which hydrolyzes 8-oxo-dGTP into 8-oxo-dGMP. The changes in this defensive system have not yet been examined in failing hearts, in which the generation of ROS increases.

METHODS AND RESULTS

Myocardial infarction (MI) was created in mice by ligating the left coronary artery. Four weeks later, the left ventricle was dilated and contractility was diminished on echocardiography. The generation of ROS, as measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, increased in the noninfarcted left ventricle from MI mice. The formation of thiobarbituric acid-reactive substances also increased in the mitochondria from MI mice. 8-Oxo-dGTPase was detected in the mitochondrial fractions isolated from MI mice using a Western blot analysis with an antibody to its human homologue (hMTH1). Immunohistochemistry showed positive staining for hMTH1 was localized in the cardiac myocytes.

CONCLUSIONS

The level of 8-oxo-dGTPase increased in the mitochondria isolated from post-MI hearts as oxidative stress increased, thus suggesting that a preventive mechanism is activated against ROS-induced DNA damage. As a result, 8-oxo-dGTPase is considered a useful marker of mitochondrial oxidative stress in heart failure.

A mutant Arabidopsis heterotrimeric G-protein beta subunit affects leaf, flower, and fruit development

A genetic screen was performed to find new mutants with an erecta (er) phenotype and to identify genes that may function with ER, a receptor-like kinase. These mutants were named elk (for erecta-like) and were placed into five complementation groups. We positionally cloned ELK4 and determined that it encodes AGB1, a putative heterotrimeric G-protein beta subunit. Therefore, elk4 was renamed agb1. agb1-1 plants express similar fruit phenotypes, as seen in er plants, but differ from er in that the stem is only slightly shorter than that in the wild type, the pedicel is slightly longer than that in the wild type, and the leaves are rounder than those in er mutants. Molecular analysis of agb1-1 indicates that it is likely a null allele. AGB1 mRNA is expressed in all tissues tested but is highest in the silique. Analysis of agb1-1 er double mutants suggests that AGB1 may function in an ER developmental pathway regulating silique width but that it functions in parallel pathways affecting silique length as well as leaf and stem development. The finding that AGB1 is involved in the control of organ shape suggests that heterotrimeric G-protein signaling is a developmental regulator in Arabidopsis.

A mutant Arabidopsis heterotrimeric G-protein beta subunit affects leaf, flower, and fruit development

A genetic screen was performed to find new mutants with an erecta (er) phenotype and to identify genes that may function with ER, a receptor-like kinase. These mutants were named elk (for erecta-like) and were placed into five complementation groups. We positionally cloned ELK4 and determined that it encodes AGB1, a putative heterotrimeric G-protein beta subunit. Therefore, elk4 was renamed agb1. agb1-1 plants express similar fruit phenotypes, as seen in er plants, but differ from er in that the stem is only slightly shorter than that in the wild type, the pedicel is slightly longer than that in the wild type, and the leaves are rounder than those in er mutants. Molecular analysis of agb1-1 indicates that it is likely a null allele. AGB1 mRNA is expressed in all tissues tested but is highest in the silique. Analysis of agb1-1 er double mutants suggests that AGB1 may function in an ER developmental pathway regulating silique width but that it functions in parallel pathways affecting silique length as well as leaf and stem development. The finding that AGB1 is involved in the control of organ shape suggests that heterotrimeric G-protein signaling is a developmental regulator in Arabidopsis.

The inhibitor of apoptosis protein survivin is associated with high-risk behavior of neuroblastoma

BACKGROUND/PURPOSE

Apoptotic factors inducing or preventing cell death may intrinsically govern the behavior of some tumors. Survivin is a recently described member of the inhibitor of apoptosis protein (IAP) family, that is expressed in a cell cycle-dependent manner and is found in tumors of unfavorable histology. This study examines the presence of several apoptotic factors, including survivin, in neuroblastoma (NB) tumors. Clues to survivin's function in NB are provided by examining its association with behavior and cell dynamics in tumors and cell lines.

METHODS

Expression of a panel of apoptosis factors were quantified in 15 NB and related tumors before chemotherapy and in 3 NB cell lines (NB7, NB10, and NB16). Survivin and other apoptotic factors, as well N-myc amplification in primary tumors was correlated with recurrent disease and outcome. Proliferation rate, apoptosis assays, cell cycle analysis, and drug- or immune-mediated cell death were assessed in cell lines and evaluated in the context of differential survivin and apoptosis gene expression.

RESULTS

All 7 tumors that went on to recur expressed survivin, whereas expression was absent in all 8 tumors that went into remission. N-myc was amplified in 4 (57.1%) of the 7 recurrent tumors. Of the 8 tumors that were cured, Fas was expressed in 3 (38%), TRAIL-R1 in 6 (75%) and tumor necrosis factor (TNF)-R1 in 8 (100%), whereas these pro-apoptotic receptors were present in only 1 (14%), 1 (14%), and 4 (57%) of the 7 tumors that went on to recur, respectively. Of the 3 cell lines, NB10 expressed the least survivin, displayed the lowest proliferation index, and had the fewest number of cells in the G2/M (mitotic) phase of the cell cycle. Furthermore, NB10 also was most sensitive to TNF-related apoptosis-inducing ligand (TRAIL) or etoposide-induced cell death.

CONCLUSIONS

In primary NB tumors, survivin expression was associated with tumors of high risk and unfavorable prognosis, whereas pro-apoptotic receptor expression was more abundant in tumors of favorable prognosis. In this small series, survivin expression appeared to be more predictive of recurrent disease than N-myc amplification. In cell lines, survivin expression was cell cycle dependent, and its expression was associated with greater proliferation rates and greater resistance to drug- or immune-mediated cell death. Survivin expression may become a useful prognostic marker in NB and could be a potential target for the treatment of this tumor. J Pediatr Surg 36:1785-1791.

B7H costimulates clonal expansion of, and cognate destruction of tumor cells by, CD8(+) T lymphocytes in vivo

B7H/B7RP (hereby called B7H) is a new member of the B7 family of costimulatory molecules and interacts with inducible costimulatory molecule (ICOS). Its function for CD8 T cells has not been reported. We report here that expression of B7H on the tumor cells reduced tumorigenicity and induced immunity to subsequent challenge with parental tumor cells. The immune protection correlates with an enhanced cytotoxic T lymphocyte (CTL) response against P1A, the major tumor antigen expressed in the J558 tumor. To understand the mechanism of immune protection, we adoptively transferred transgenic T cells specific for tumor antigen P1A into mice that bore P1A-expressing tumors. We found that while the transgenic T cells divided faster in mice bearing the B7H(+) tumors, optimal B7H-induced clonal expansion of P1CTL required costimulation by B7-1 and B7-2 on the endogenous host antigen-presenting cells (APCs). Interestingly, when B7H(+) and B7H(-) tumors were coinjected, P1CTL selectively eliminated the B7H(+) tumor cells. Moreover, B7H expressed on the tumor cells made them highly susceptible to destruction by CTL in vivo, even if the CTL was administrated into mice with large tumor burdens. Tumors that recurred in the P1CTL-treated mice lost transfected B7H and/or H-2L(d), the class I molecule that presents the P1A peptide. Taken together, our results reveal that B7H costimulates clonal expansion of, and cognate destruction by CD8(+) T lymphocytes in vivo.

Environment of tryptophan 57 in porcine fructose-1,6-bisphosphatase studied by time-resolved fluorescence and site-directed mutagenesis

The environment of Trp57, introduced by the mutation of a tyrosine in the dynamic loop of porcine liver fructose-1,6-bisphosphatase (FBPase), was examined using time-resolved fluorescence and directed mutation. The Trp57 enzyme was studied previously by X-ray crystallography and steady-state fluorescence, the latter revealing an unexpected redshift in the wavelength of maximum fluorescence emission for the R-state conformer. The redshift was attributed to the negative charge of Asp127 in contact with the indole side chain of Trp57. Time-resolved fluorescence experiments here reveal an indole side chain less solvent exposed and more rigid in the R-state, than in the T-state of the enzyme, consistent with X-ray crystal structures. Replacement of Asp127 with an asparagine causes a 6 nm blueshift in the wavelength of maximum fluorescence emission for the R-state conformer, with little effect on the emission maximum of the T-state enzyme. The data here support the direct correspondence between X-ray crystal structures of FBPase and conformational states of the enzyme in solution, and provide a clear example of the influence of microenvironment on the fluorescence properties of tryptophan.

[Expression of ADAM12 (Meltrin-alpha) gene in giant cell tumor of bone]

OBJECTIVE

To detect expression and location of ADAM12 (meltrin-alpha) gene in giant cell tumor of bone and to study its effect on the formation of multinucleated giant cells in the tumor.

METHODS

ADAM12 mRNA was detected by RT-PCR and RNA in situ hybridization in 18 cases of giant cell tumors, 6 cases of cultured tumor cells, 2 specimens of embryonic muscle tissue and 5 specimens of adult muscle tissue.

RESULTS

RT-PCR showed that 12/18 (67%) cases of giant cell tumor of bone expressed ADAM12 mRNA. RNA in situ hybridization demonstrated positive ADAM12 mRNA in 12 cases of the detected tumors. The ADAM 12 mRNA positive signal was localized in the cytoplasm of almost all multinucleated giant cells and mononuclear stromal cells. However, the expression of ADAM12 mRNA decreased gradually, and eventually lost with increased passages of tumor cells and the disappearance of multinucleated giant cells in the culture.

CONCLUSION

Multinucleated giant cells probably originated from the fusion of mononuclear stromal cells and ADAM12 may participate in the fusion process.

On the site and mode of antigen presentation for the initiation of clonal expansion of CD8 T cells specific for a natural tumor antigen

Because of the low frequency of antigen-specific T cells, early events in the activation of tumor-specific T cells in vivo have not been well characterized. There is still no direct documentation on where the clonal expansion begins and how tumor antigens are presented to the host CD8 T cells to initiate it. Here we used transgenic T cells specific for a natural tumor antigen P1A to evaluate the kinetics, location, and modes of antigen presentation for initiating CTL response in vivo. Our results demonstrate that the initial activation of P1A-specific T cells takes place in the lymphoid organs. The activated T cells then migrate into tumors, where they undergo accelerated division and acquire distinct activation markers. The site of initiation cannot be altered by either local expression of costimulatory molecules or by intratumor injection of naïve T cells. Moreover, using genetic models that allow only one mode of antigen presentation, we show here that both cross-presentation of P1A by the host antigen-presenting cells, and direct antigen presentation and costimulation by the tumor cells are sufficient to initiate rapid T cell-clonal expansion in the lymphoid organ. These results provide direct evidence for two fundamental assumptions on the mechanisms of T-cell activation in vivo.

Tumor cell toxicity of hypericin and related analogs

A series of hypericin analogs were found to differ in their cytotoxic activity induced by ambient light levels. These analogs vary in their ability to partition into cells, to generate singlet oxygen as well as in other photophysical properties. The data suggest that the biological activity of hypericin is due to a combination of factors whose roles may vary under different circumstances.

Enhanced generation of reactive oxygen species in the limb skeletal muscles from a murine infarct model of heart failure

BACKGROUND

The generation of reactive oxygen species (ROS) is enhanced in the failing myocardium. We hypothesized that ROS were also increased in the limb skeletal muscles in heart failure. Methods and Results-- Myocardial infarction (MI) was created in mice by ligating the left coronary artery. After 4 weeks, the left ventricle was dilated and contractility was diminished by echocardiography. Left ventricular end-diastolic pressure was elevated after MI in association with an increase in lung weight/body weight and the presence of pleural effusion. The generation of ROS in the limb muscles, including the soleus and gastrocnemius muscles, which were excised after MI, was measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (hydroxy-TEMPO). Overall, generation was increased, but it was attenuated in the presence of dimethylthiourea or 4,5-dihydroxy-1,2-benzenedisulfonic disodium salt in the reaction mixture, indicating increased generation of hydroxyl radicals originating from superoxide anion. Thiobarbituric acid-reactive substance formation was also increased in muscles after MI. Mitochondrial complex I and III activities were both decreased after MI, which may have caused the functional uncoupling of the respiratory chain and ROS production. Antioxidant enzyme activities, including superoxide dismutase, catalase, and glutathione peroxidase, were comparable between groups.

CONCLUSIONS

Skeletal muscle in post-MI heart failure expressed an increased amount of ROS in association with ROS-mediated lipid peroxidation. This supports the hypothesis that oxidative stress may cause (at least in part) skeletal muscle dysfunction in heart failure.

Copper staining method for extracting biologically active proteins from native gels

An attempt was made to make protein bands visible on native gel using copper staining, since such a mild staining procedure would make the entire native gel electrophoresis process non-denaturing. Copper staining not only was able to detect various proteins on native gel with reasonable sensitivity, but also made extraction and recovery of active proteins possible from the gel using a gentle procedure.

Transfer of cobalamin from intrinsic factor to transcobalamin II

The process is obscure by which cobalamin (Cbl) in the endocytosed intrinsic factor (IF)-cobalamin (Cbl) complex is released and transferred to transcobalamin II (TCII) within the enterocyte. Using recombinant IF and TCII, binding of Cbl to IF at pH 5.0 was 70% of binding at pH 7.0, whereas for TCII alone, the value was only 12%. TCII binding activity was lost rapidly at lower pH, but this was not due to protease action. TCII incubated at pH 5.0 with cathepsin L was degraded and could not subsequently bind Cbl. Thus, transfer from IF to TCII is unlikely to occur within an acid compartment. Only 13-15% of bound Cbl was released at pH 5.0 and pH 6.0 from either rat IF, human IF, or human TCII. The K(a) of human or rat IF at pH 7.5 was 2.2 nM; for TCII, the value was 0.34 nM. At pH 7.5, Cbl transfers from IF to TCII, but only to a limited extent (21%), as detected by nondenaturing electrophoresis. Transfer of Cbl from IF to TCII could not be demonstrated at pH values of 5.0 or 6.0. Thus, luminal transfer of Cbl between IF and TCII is likely to be limited, but is possible. The most likely mechanism for intracellular transfer of Cbl from IF to TCII involves initial lysosomal proteolysis of IF, with subsequent Cbl binding to TCII in a more neutral cellular compartment.

Purification and characterization of the fatty acid synthase from Bugula neritina

The fatty acid synthase from Bugula neritina has been purified 100-fold using ammonium sulfate precipitation, ion-exchange and size exclusion chromatography. The purified enzyme has a molecular weight of approximately 382,000 Da, as judged by gel filtration. Polyacrylamide gel electrophoresis under denaturing conditions in the presence of SDS revealed one major protein band of approximately 190,000 Da suggesting that the enzyme is a homodimer. The size of the enzyme, together with the observation that the FAS activity is independent of the concentration of acyl carrier protein, indicate that the FAS from Bugula neritina is a type I. A detailed analysis of the products of the purified FAS indicated that palmitic acid is the primary product and longer chain fatty acids are not produced.

The E2F6 transcription factor is a component of the mammalian Bmi1-containing polycomb complex

The E2F transcription factors play a key role in the regulation of cellular proliferation and terminal differentiation. E2F6 is the most recently identified and the least well understood member of the E2F family. It is only distantly related to the other E2Fs and lacks the sequences responsible for both transactivation and binding to the retinoblastoma protein. Consistent with this finding, E2F6 can behave as a dominant negative inhibitor of the other E2F family members. In this study, we continue to investigate the possible role(s) of E2F6 in vivo. We report the isolation of RYBP, a recently identified member of the mammalian polycomb complex, as an E2F6-interacting protein. Mapping studies indicate that RYBP binds within the known "repression domain" of E2F6. Moreover, we demonstrate that endogenous E2F6 and polycomb group proteins, including RYBP, Ring1, MEL-18, mph1, and the oncoprotein Bmi1, associate with one another. These findings suggest that the biological properties of E2F6 are mediated through its ability to recruit the polycomb transcriptional repressor complex.

Asn to Lys mutations at three sites which are N-glycosylated in the mammalian protein decrease the aggregation of Escherichia coli-derived erythropoietin

Erythropoietin (EPO) derived from Escherichia coli is unstable to elevated temperature and tends to aggregate with time, making it unsuitable for high-resolution structure analysis. The mammalian EPO contains about 40% carbohydrate, which makes this protein more stable and less prone to aggregate than non-glycosylated E.coli-derived EPO, but makes it unsuitable for high-resolution analysis owing to its size and flexibility. In an attempt to decrease the aggregation of E.coli-derived EPO, the three asparagine residues at positions 24, 38 and 83 were mutated to lysine residues. In the native protein, these residues are the sites of N-linked glycosylation, which suggests that they should be located on the surface of the protein and should not be involved in interactions in the hydrophobic protein core. Therefore, the substitution of basic amino acids for these neutral asparagine residues is not expected to affect the protein structure, but should increase the isoelectric point of the protein and its net positive charge, decreasing its tendency to aggregate at or below neutral pH due to electrostatic interactions. No apparent alterations in receptor binding, as determined by both cell-surface receptor competition assay and in vitro receptor dimerization experiments, were observed when these mutations were introduced into the EPO sequence. However, this mutant protein displayed a significant increase in stability to heat treatment and to storage, relative to the wild-type molecule. This resulted in a greater number of observable cross peaks in the mutant EPO in 2D NOESY experiments. However, the mutant was similar to the wild-type in stability when urea was used as a denaturant. This indicates that the introduced mutations resulted in a decrease in aggregation with heating or with prolonged incubation at ambient temperature, without changing the conformational stability or the receptor binding affinity of the mutant protein. This approach of placing charged residues at sites where N-glycosylation occurs in vivo could be applied to other systems as well.

NASA/American Cancer Society High-Resolution Flow Cytometry Project - III. Multiparametric analysis of DNA content and electronic nuclear volume in human solid tumors

BACKGROUND

The NASA/American Cancer Society (ACS) flow cytometer can simultaneously measure electronic nuclear volume (ENV) and DNA content of nuclei. The preceding articles in this volume ("NASA/American Cancer Society High-Resolution Flow Cytometer Project-I") described the schematics, performance, and procedures used for the preparation of nuclei for analysis on this unit. In the present article, we describe the analysis of selected human tumors using the ratio of ENV/DNA content (nuclear packing efficiency [NPE]).

METHODS

Tumor specimens (frozen) were minced with scalpels and stained with 1-10 microg/ml of 4',6-diamidino-2-phenylindole (DAPI) dihydrochloride at pH 6.0-7.2. Trout erythrocytes were used as internal standards. Data on ENV and DNA content were collected in list mode files. Propidium iodide-stained nuclei, analyzed on a Coulter XL cytometer, were used for comparison.

RESULTS

Simultaneous measurement of ENV and DNA makes it possible to discriminate between hypodiploid or hyperdiploid tumor cells, as well as to differentiate between near-diploid aneuploid and diploid cells on the basis of their increased ENV. The NPE ratio is a valuable parameter for the detection of small quantities of tumor cells, separating overlapping diploid and aneuploid populations for cell cycle analysis and characterizing the level of differentiation in some tumors.

CONCLUSION

NPE analysis provides unique measuring capabilities for the study of human solid tumors by flow cytometry.

NASA/American Cancer Society High-Resolution Flow Cytometry Project - II. Effect of pH and DAPI concentration on dual parametric analysis of DNA/DAPI fluorescence and electronic nuclear volume

BACKGROUND

In the present paper, we describe the effect of 4', 6-diamidino-2-phenylindole (DAPI) dihydrochloride concentration and pH on the resolution of DNA distribution histograms generated by dual-parametric simultaneous analysis of DNA content and electronic nuclear volume (ENV).

METHODS

Nuclei from tissue culture cell lines and frozen human solid tumors were isolated in nuclear isolation media containing different concentrations of DAPI, at various pH levels, and analyzed on a NASA/American Cancer Society (ACS) flow cytometer. Samples stained with propidium iodide/hypotonic citrate and analyzed in a Coulter XL flow cytometer were used for comparison.

RESULTS

Nuclei stained with DAPI concentration of 1-3 microg/ml, pH 6.0, gave the best resolution for the detection of the near-diploid and near-tetraploid populations. Simultaneous use of ENV and DAPI/DNA fluorescence under these conditions identified subpopulations that otherwise could not be detected by DNA analysis alone.

CONCLUSIONS

Staining at 1-3 microg/ml DAPI, pH 6.0, was optimal for the detection of aneuploid populations, especially the near-diploid and/or near-tetraploid populations in human tumors.

The survivin:fas ratio in pediatric renal tumors

BACKGROUND/PURPOSE

Apoptosis factors inducing or preventing cell death may govern the behavior of certain tumors. Fas is a pro-apoptotic receptor that induces cell death when bound by its ligand and is expressed at greater levels in pediatric renal tumors of good prognosis. Survivin is a novel inhibitor of apoptosis that is expressed in a cell cycle-dependent manner and is abundantly expressed in several tumors of unfavorable histology. This study evaluates the expression of survivin, as well as the prognostic value of the survivin:fas ratio in various types and stages of pediatric renal tumors.

METHODS

Multiple apoptosis mRNA species were quantified by Rnase protection assay (RPA) in 32 pediatric renal tumors and adjacent normal kidney specimens before chemotherapy: Wilms' tumor (WT), n = 9; clear cell sarcoma (CCS), n = 4; rhabdoid tumor of the kidney (RTK), n = 5; mesoblastic nephroma (MN), n = 3 and normal kidney, n = 11. Western Blot and immunocytochemistry were used to confirm survivin protein expression in a selective specimen survey. Follow-up data were obtained on patient outcomes, and antiapoptotic to proapoptotic ratios were calculated and correlated with clinical recurrence of disease.

RESULTS

Pediatric renal tumors express greater levels of both pro- and antiapoptotic factors than normal kidney. Survivin and fas appeared to be expressed differentially in the tumor specimens sampled. Five of 10 (50%) tumors that went on to recur expressed survivin, whereas survivin was present in only 2 of 11 (18%) nonrecurrent tumors. Conversely, only 2 of 10 (20%) tumors that recurred were fas positive, whereas 5 of 11 (45%) tumors that did not recur expressed fas. The mean survivin:fas ratio was significantly greater in the 10 tumors that went on to recur after treatment (4 RTK, 3 CCS, 3 WT), than in tumors not recurring (2.16+/-1.4 v 1.0+/-1.07; P =.01, Kruskal-Wallis test). The positive predictive value of tumor recurrence was 85.7% (CI: 42.1%, 99.6%) and the negative predictive value was 71.4% (CI: 41.9%, 91.6%) when a cutoff ratio of 1.6 was considered.

CONCLUSIONS

The survivin:fas mRNA ratio is of prognostic value in its ability to predict recurrent disease in children undergoing treatment for pediatric renal tumors. In this series, a ratio of greater than 1.6 predicted recurrent disease with a high probability irrespective of clinical stage or pathologic type. Determining the survivin:fas ratio may guide treatment, follow-up and counseling of patients with pediatric renal tumors.

A phylogenetic analysis of Prunus and the Amygdaloideae (Rosaceae) using ITS sequences of nuclear ribosomal DNA

The economically important plum or cherry genus (PRUNUS:) and the subfamily Amygdaloideae of the Rosaceae have a controversial taxonomic history due to the lack of a phylogenetic framework. Phylogenetic analysis using the ITS sequences of nuclear ribosomal DNA (nrDNA) was conducted to construct the evolutionary history and evaluate the historical classifications of PRUNUS: and the Amygdaloideae. The analyses suggest two major groups within the Amygdaloideae: (1) PRUNUS: s.l. (sensu lato) and MADDENIA:, and (2) EXOCHORDA:, Oemleria, and PRINSEPIA: The ITS phylogeny supports the recent treatment of including EXOCHORDA: (formerly in the Spiraeoideae) in the Amygdaloideae. MADDENIA: is found to be nested within PRUNUS: s.l. in the parsimony and distance analyses, but basal to PRUNUS: s.l. in the maximum likelihood analysis. Within PRUNUS:, two major groups are recognizable: (1) the AMYGDALUS:-PRUNUS: group, and (2) the CERASUS:-LAUROCERASUS:-PADUS: group. The clades in the ITS phylogeny are not congruent with most subgeneric groups in the widely used classification of PRUNUS: by Rehder. A broadly defined PRUNUS: is supported.

Antileukemic drugs increase death receptor 5 levels and enhance Apo-2L-induced apoptosis of human acute leukemia cells

In present studies, treatment with tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL, also known as Apo-2 ligand [Apo-2L]) is shown to induce apoptosis of the human acute leukemia HL-60, U937, and Jurkat cells in a dose-dependent manner, with the maximum effect seen following treatment of Jurkat cells with 0.25 microg/mL of Apo-2L (95.0% +/- 3.5% of apoptotic cells). Susceptibility of these acute leukemia cell types, which are known to lack p53(wt) function, did not appear to correlate with the levels of the apoptosis-signaling death receptors (DRs) of Apo-2L, ie, DR4 and DR5; decoy receptors (DcR1 and 2); FLAME-1 (cFLIP); or proteins in the inhibitors of apoptosis proteins (IAP) family. Apo-2L-induced apoptosis was associated with the processing of caspase-8, Bid, and the cytosolic accumulation of cytochrome c as well as the processing of caspase-9 and caspase-3. Apo-2L-induced apoptosis was significantly inhibited in HL-60 cells that overexpressed Bcl-2 or Bcl-x(L). Cotreatment with either a caspase-8 or a caspase-9 inhibitor suppressed Apo-2L-induced apoptosis. Treatment of human leukemic cells with etoposide, Ara-C, or doxorubicin increased DR5 but not DR4, Fas, DcR1, DcR2, Fas ligand, or Apo-2L levels. Importantly, sequential treatment of HL-60 cells with etoposide, Ara-C, or doxorubicin followed by Apo-2L induced significantly more apoptosis than treatment with Apo-2L, etoposide, doxorubicin, or Ara-C alone, or cotreatment with Apo-2L and the antileukemic drugs, or treatment with the reverse sequence of Apo-2L followed by one of the antileukemic drugs. These findings indicate that treatment with etoposide, Ara-C, or doxorubicin up-regulates DR5 levels in a p53-independent manner and sensitizes human acute leukemia cells to Apo-2L-induced apoptosis. (Blood. 2000;96:3900-3906)

[Dynamic changes of respiration pathway and active oxygen levels in subcultured tobacco callus]

During the growth and senescence of tobacco callus, the total respiration rate showed two peaks on the 11th and 19th day, respectively. The development and operation of alternative pathway increased gradually, reached the maximum between two respiration peaks, and then declined in the following days, but the cytochrome pathway was still as a main electron transport pathway consistently. Analysis on the levels of active oxygen species during the growth and senescence process in tobacco callus suggested that H2O2 and O2.- were involved in some way in the induction of the development and operation of the alternative pathway, but the increase of production rate of OH might suppress both the development and operation of the alternative pathway, which were enhanced by H2O2 and O2.- respectively. These results were further proved by the use of active oxygen scavengers. The possible participation of the alternative pathway enhanced by active oxygen in the initial senescence process was discussed.

[The expression of DNA mismatch repair genes and detection of DNA ploidy in young patients with colorectal carcinoma]

OBJECTIVE

To investigate the clinicopathologic characters and carcinogentic pathways of young (age < 36) colorectal carcinomas (CRCs) in Guangzhou, China.

METHODS

Immunohistochemistry and flow cytometry methods were used to detect the expression of hMSH(2) and hMLH(1), status of DNA ploidy in 63 cases of young CRCs from Guangzhou, China, and analyze their correlations with patient's clinicopathological characters.

RESULTS

Of the 63 young CRCs studied, forty-four (69.8%) tumors were non-mucinous carcinomas, thirty-nine (61.9%) patients were in Dukes' C or D stage. Of the 59 CRCs which were successfully detected by immunohistochemistry and flow cytometry, ten (16.9%) CRCs lost either hMSH(2) or hMLH(1) and showed DNA diploid or near-diploid, while twenty-six (44.1%) had aneuploid DNA content and all with the normal expression of hMSH(2) and hMLH(1). In addition, there existed a significant percentage (23/59, 39%) of young CRCs showing no loss of either of these two mismatch repair proteins and having a diploid or near diploid DNA content.

CONCLUSION

The overall percentage of young CRCs in Guangzhou is significantly higher than those in Caucasian predominant countries and about seventy percent of young CRCs in Guangzhou are conventional carcinomas. 39% of young CRCs in Guangzhou showed no evidence of either chromosomal instability or microsatellite instability carcinogentic pathway, indicating that there must be at least a third pathway which triggers the CRCs in these special subgroups of young patients in Guangzhou, China.