Polymerase chain reaction based assay to detect allelic loss in human DNA: loss of beta-interferon gene in chronic myelogenous leukemia

Immunomodulatory and antitumor effects of type I interferons and their application in cancer therapy

During the last decades, the pleiotropic antitumor functions exerted by type I interferons (IFNs) have become universally acknowledged, especially their role in mediating interactions between the tumor and the immune system. Indeed, type I IFNs are now appreciated as a critical component of dendritic cell (DC) driven T cell responses to cancer. Here we focus on IFN-α and IFN-β, and their antitumor effects, impact on immune responses and their use as therapeutic agents. IFN-α/β share many properties, including activation of the JAK-STAT signaling pathway and induction of a variety of cellular phenotypes. For example, type I IFNs drive not only the high maturation status of DCs, but also have a direct impact in cytotoxic T lymphocytes, NK cell activation, induction of tumor cell death and inhibition of angiogenesis. A variety of stimuli, including some standard cancer treatments, promote the expression of endogenous IFN-α/β, which then participates as a fundamental component of immunogenic cell death. Systemic treatment with recombinant protein has been used for the treatment of melanoma. The induction of endogenous IFN-α/β has been tested, including stimulation through pattern recognition receptors. Gene therapies involving IFN-α/β have also been described. Thus, harnessing type I IFNs as an effective tool for cancer therapy continues to be studied.

Ongoing Monoclonal B-Cell Proliferation Is Not Common in Gastric B-Cell Lymphoma After Combined Radiochemotherapy

Purpose

Gastric marginal-zone B-cell lymphoma (MZBCL) of the mucosa-associated lymphoid tissue (MALT) is associated with chronic Helicobacter pylori gastritis. Stable complete remission (CR) can be induced by H pylori eradication. Whether this is paralleled by cure of the lymphoma remains unclear. Persisting monoclonal bands for immunoglobulin heavy chain variable region (VH) representing the lymphoma clone have been described in up to 50% of patients in CR. This retrospective study investigated whether this phenomenon also occurs after radiochemotherapy.

Patients and Methods

Biopsy samples of 20 patients receiving chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone and irradiation were analyzed before and after therapy. Study patients had Ann Arbor stage I/II primary gastric cancer, including four cases of MZBCL of MALT type, 12 cases of diffuse large-cell lymphomas (DLCL), and four cases of mixed MALT type/DLCL. Polymerase chain reaction (PCR) for VH rearrangement was performed. Monoclonal PCR products were cloned and sequenced.

Results

Fourteen of 20 patients had a monoclonal or oligoclonal band distribution at diagnosis converted into polyclonal pattern after radiochemotherapy. Of the remaining six patients, two were lost to follow-up. One patient did not respond and died of progressive disease. PCR in this patient showed persistent B-cell clonality. In three patients, the initial PCR showed a polyclonal pattern and thus could not be evaluated during follow-up.

Conclusion

In contrast with H pylori eradication alone, radiochemotherapy results in clearing of monoclonal cells during follow-up. This may result in better elimination of residual lymphoma cells. Further study is needed to determine whether this translates into lower risk of relapse.

Regulation of complement C3 and C4 synthesis in human peritoneal mesothelial cells by peritoneal dialysis fluid

Although complement is activated in the peritoneal cavity during chronic peritoneal dialysis (PD), little is known about its role in peritoneal defence and injury related to long-term PD. We examined the impact of glucose and commercial peritoneal dialysis solutions on complement expression in HPMCs obtained by primary culture from omental tissues of consented patients undergoing elective abdominal surgery. Constitutive expression of C3 and C4 mRNA in HPMCs was up-regulated upon exposure to 75 mm glucose in a time-dependent manner. C3 and C4 protein was secreted in both apical and basolateral directions. Glucose doses beyond 100 mm markedly down-regulated C3 and C4 expression, and stimulated LDH release dose-dependently. Such cytotoxic effects were attenuated using equivalent doses of mannitol instead of glucose. Treatment with conventional lactate-buffered dialysis solution gave rise to down-regulation of C3 and C4 expression, and heightened LDH release in HPMCs. These effects correlated with the glucose strength of the solution, persisted despite replacement with a bicarbonate-buffered solution, aggravated by glycated albumin, and were partially abrogated by supplementation with 10% fetal bovine serum in the culture system. Our findings suggest that the artificial conditions imposed by PD lead to alterations in local complement synthesis that have implications for the role of the peritoneal mesothelium in both inflammation and defence.

Albumin stimulates interleukin-8 expression in proximal tubular epithelial cells in vitro and in vivo

Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the stimuli for leukocyte recruitment are not fully understood. IL-8 is a potent chemokine produced by proximal tubular epithelial cells (PTECs). Whether nephrotic proteins stimulate tubular IL-8 expression remains unknown. Acute exposure of human PTECs to albumin induced IL-8 gene and protein expression time- and dose-dependently. Apical albumin predominantly stimulated basolateral IL-8 secretion. Electrophoretic mobility shift assay demonstrated nuclear translocation of NF-kappaB, and the p65/p50 subunits were activated. NF-kappaB activation and IL-8 secretion were attenuated by the NF-kappaB inhibitors pyrrolidine dithiocarbamate and cell-permeable peptide. Albumin upregulated intracellular reactive oxygen species (ROS) generation, while exogenous H2O2 stimulated NF-kappaB translocation and IL-8 secretion. Albumin-induced ROS generation, NF-kappaB activation, and IL-8 secretion were endocytosis- and PKC-dependent as these downstream events were abrogated by the PI3K inhibitors LY294002 and wortmannin, and the PKC inhibitors GF109203X and staurosporin, respectively. In vivo, IL-8 mRNA expression was localized by in situ hybridization to the proximal tubules in nephrotic kidney tissues. The intensity of IL-8 immunostaining was higher in nephrotic than non-nephrotic subjects. In conclusion, albumin is a strong stimulus for tubular IL-8 expression, which occurs via NF-kappaB-dependent pathways through PKC activation and ROS generation.

High throughput screening of human subtelomeric DNA for copy number changes using multiplex amplifiable probe hybridisation (MAPH)

BACKGROUND

Subtelomeric regions of the human genome are gene rich, with a high level of sequence polymorphism. A number of clinical conditions, including learning disability, have been attributed to subtelomeric deletions or duplications, but screening for deletion in these regions using conventional cytogenetic methods and fluorescence in situ hybridisation (FISH) is laborious. Here we report that a new method, multiplex amplifiable probe hybridisation (MAPH), can be used to screen for copy number at subtelomeric regions.

METHODS

We have constructed a set of MAPH probes with each subtelomeric region represented at least once, so that one gel lane can assay copy number at all chromosome ends in one person. Each probe has been sequenced and, where possible, its position relative to the telomere determined by comparison with mapped clones.

RESULTS

The sensitivity of the probes has been characterised on a series of cytogenetically verified positive controls and 83 normal controls were used to assess the frequency of polymorphic copy number with no apparent phenotypic effect. We have also used MAPH to test a cohort of 37 people selected from males referred for fragile X syndrome testing and found six changes that were confirmed by dosage PCR.

CONCLUSIONS

MAPH can be used to screen subtelomeric regions of chromosomes for deletions and duplications before confirmation by FISH or dosage PCR. The high throughput nature of this technique allows it to be used for large scale screening of subtelomeric copy number, before confirmation by FISH. In practice, the availability of a rapid and efficient screen may allow subtelomeric analysis to be applied to a wider selection of patients than is currently possible using FISH alone.

The detection of large deletions or duplications in genomic DNA

While methods for the detection of point mutations and small insertions or deletions in genomic DNA are well established, the detection of larger (>100 bp) genomic duplications or deletions can be more difficult. Most mutation scanning methods use PCR as a first step, but the subsequent analyses are usually qualitative rather than quantitative. Gene dosage methods based on PCR need to be quantitative (i.e., they should report molar quantities of starting material) or semi-quantitative (i.e., they should report gene dosage relative to an internal standard). Without some sort of quantitation, heterozygous deletions and duplications may be overlooked and therefore be under-ascertained. Gene dosage methods provide the additional benefit of reporting allele drop-out in the PCR. This could impact on SNP surveys, where large-scale genotyping may miss null alleles. Here we review recent developments in techniques for the detection of this type of mutation and compare their relative strengths and weaknesses. We emphasize that comprehensive mutation analysis should include scanning for large insertions and deletions and duplications.

Analysis of FLT3-activating mutations in 979 patients with acute myelogenous leukemia: association with FAB subtypes and identification of subgroups with poor prognosis

Constitutive activation of the FLT3 receptor tyrosine kinase, either by internal tandem duplication (ITD) of the juxtamembrane region or by point mutations in the second tyrosine kinase domain (TKD), has been described in patients with acute myelogenous leukemia (AML). We analyzed the prevalence and the potential prognostic impact of FLT3 mutations in 979 AML patients. Results were correlated with cytogenetic data and the clinical response. FLT3-ITD mutations were found in 20.4% and FLT3-TKD mutations in 7.7% of the patients. Each mutation was associated with similar clinical characteristics and was more prevalent in patients with normal karyotype. Significantly more FLT3 aberrations were found in patients with FAB M5, and fewer were found in patients with FAB M2 and M6. Although less frequent in patients with cytogenetic aberrations, FLT3-ITDs were found in 13 of 42 patients with t(15;17) and in 9 of 10 patients with t(6;9). The prevalence of the ITD allele on the DNA level was heterogeneous, ranging from faint mutant bands in some patients to predominant mutant bands in others. Based on quantitative analysis, the mutant-wild-type (wt) ratio ranged from 0.03 to 32.56 (median, 0.78). Patients with a high mutant/wt ratio (ie, greater than 0.78) had significantly shorter overall and disease-free survival, whereas survival in patients with ratios below 0.78 did not differ from those without FLT3 aberrations. Multivariate analysis confirmed a high mutant/wt ratio to be a strong independent prognostic factor. Taken together, these data confirm that FLT mutations represent a common alteration in adult AML. Constitutive activation may be associated with monocytoid differentiation. A high mutant/wt ratio in ITD-positive patients appears to have a major impact on the prognostic relevance.

Transferrin up-regulates chemokine synthesis by human proximal tubular epithelial cells: implication on mechanism of tubuloglomerular communication in glomerulopathic proteinura

BACKGROUND

The pathogenesis of glomerulosclerosis and tubulointerstitial fibrosis in proteinuric renal disease is obscure. We recently showed that transferrin, a key proteinuric component, mediates proximal tubular epithelial cell (PTEC) C3 synthesis. To further examine whether proteinuric tubular injury may induce glomerular inflammation and to characterize the role of transferrin in activating PTEC, glomerular mesangial cells (MC) were exposed to transferrin-activated PTEC culture supernatant and their proliferative and profibrotic responses analyzed.

METHODS

Human PTEC and MC were obtained by primary culture. Confluent, transferrin-stimulated PTEC were grown in serum-free medium to produce a "conditioned" medium that was incubated with quiescent MC. The proliferative response of MC was then assessed by thymidine uptake, and the expression of fibrogenic factors measured by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The chemokine profile in PTEC after transferrin treatment was examined by RT-PCR and ELISA.

RESULTS

"Conditioned" supernatant from PTEC, which contained the highest amounts of platelet-derived growth factor (PDGF), stimulated MC proliferation compared with serum-free (P = 0.03) or transferrin-containing (P = 0.009) control media. This proliferative response was partially abrogated by treating MC with anti-PDGF. MC expression of PDGF, but not transforming growth factor-beta or intercellular cell adhesion molecule-1, was up-regulated by conditioned PTEC medium. Transferrin up-regulated monocyte chemoattractant peptide-1, interleukin-8, and macrophage migration inhibitory factor expression in a time- and dose-dependent fashion, but had no effect on RANTES expression by PTEC.

CONCLUSIONS

These results provide experimental evidence suggesting that there is a tubuloglomerular "cross-talk" mechanism in the proteinuric state. PTEC-secreted PDGF, which further induces mesangial PDGF, could partially account for the mesangial proliferation frequently observed in proteinuric renal disease. Transferrin is one of the culprit nephrotic proteins leading to tubular overexpression of various proinflammatory chemokines, which may explain the interstitial changes observed in proteinuric states.

Translational regulation of renal proximal tubular epithelial cell transforming growth factor-beta1 generation by insulin

We have previously demonstrated that the proximal tubular cell may contribute to the pathogenesis of renal interstitial fibrosis in diabetes. Transforming growth factor (TGF)-beta1 is one of a group of pro-fibrotic cytokines and growth factors, which have been associated with the development of interstitial fibrosis. The aim of the current study was to examine the effect of insulin on the generation of TGF-beta1 by proximal tubular cells. HK-2 cells were grown to confluence in the absence of insulin, and serum deprived for 48 hours before all experimental manipulations. Addition of insulin (5 microg/ml) to the culture medium led to a time-dependent increase in TGF-beta1 concentration in the cell culture supernatant, and increased incorporation of radiolabeled amino acids into TGF-beta1 suggestive of de novo TGF-beta1 protein synthesis. Addition of insulin did not alter TGF-beta1 mRNA expression as assessed by reverse transcriptase-polymerase chain reaction or Northern analysis. Insulin-induced increase in TGF-beta1 concentration was not abrogated by actinomycin D, however, stimulation by insulin, in the presence of cycloheximide led to a dose-dependent decrease in TGF-beta1 production. Addition of insulin had no effect on TGF-beta1 mRNA stability as assessed by actinomycin D chase, but led to increased binding of a cytoplasmic protein to a putative stem loop structure in the 5'-UTR of TGF-beta1 mRNA, previously implicated in the posttranscriptional control of TGF-beta1 synthesis. To address the functional significance of insulin-induced alteration in TGF-beta1 synthesis, we examined its effect on matrix turnover. Insulin stimulated type IV collagen gene expression and an increase in the concentrations of the type IV collagen laid down in the extracellular matrix. This increase in type IV collagen was abrogated when cells were stimulated by insulin in the presence of an anti-TGF-beta1-blocking antibody. In conclusion the data demonstrate that insulin may directly alter the production of TGF-beta1 by renal proximal tubular cells by a posttranscriptional mechanism, and that this may have implications for the increase in extracellular matrix that accompanies diabetic nephropathy.

Regulation of renal proximal tubular epithelial cell fibroblast growth factor-2 generation by heparin

Progression of renal disease is closely correlated to the degree of renal interstitial fibrosis, and evidence is increasing that epithelial cells of the renal proximal tubule (PTCs) may contribute to its pathogenesis. Such cytokines as basic fibroblast growth factor (FGF-2) have been implicated in progressive renal injury, and we previously showed that PTCs are a source of this cytokine. FGF-2 is characterized by its high affinity for heparin, and numerous studies have suggested that heparin may modify the progression of renal disease. The current study examined how heparin influenced FGF-2 generation and bioactivity in the human renal epithelial PTC line, HK-2. Incubation of HK-2 cells with heparin led to a dose- and time-dependent increase in FGF-2 concentration in the culture supernatant that was not accompanied by alterations in FGF-2 messenger RNA expression, assessed by reverse-transcriptase polymerase chain reaction and Northern analysis. The heparin-induced increase in FGF-2 concentration was accompanied by a decrease in the amount of FGF-2 bound to the extracellular matrix, although this accounted for only a small proportion of the total FGF-2 generated. Induction of FGF-2 by 2-O-desulfated heparin, together with a reduction in total cell-associated FGF-2 and anti-FGF-2 antibody binding to fixed permeabilized cells after the addition of heparin, suggested that the FGF-2 released was mainly derived from a preformed intracellular source. That FGF-2 was predominantly derived from an intracellular pool was also confirmed by pulse chase experiments. The addition of heparin resulted in the generation of bioinactive FGF-2, judged by in vitro fibroblast proliferation. Conversely, heparitinase treatment of supernatant samples from heparin-treated cells and the addition of 2-O-desulfated heparin resulted in the generation of active FGF-2, suggesting that the generation of bioinactive FGF-2 was related to binding of FGF-2 by extracellular heparin after its release from cells. These data show that heparin depletes both the cell and surrounding matrix of FGF-2 and suggest that FGF-2 released from cells was mainly derived from a preformed intracellular source. Furthermore, FGF-2 released from epithelial PTCs after the application of heparin was bioinactive. This likely resulted from released FGF-2 binding to an excess of extracellular heparin. Results presented here therefore suggest a mechanism by which heparin, through its effect on depletion of matrix and cells of FGF-2 and its generation in an inactive form, may influence progressive renal interstitial fibrosis.

Expression of inter-alpha-trypsin inhibitor and tumor necrosis factor-stimulated gene 6 in renal proximal tubular epithelial cells

BACKGROUND

Our previous studies have demonstrated that renal proximal tubular epithelial cells (PTCs) may contribute to renal interstitial fibrosis by the generation of transforming growth factor-beta1 (TGF-beta1). In these in vitro experiments, TGF-beta1 was, however, secreted in its latent form. Plasmin has been implicated as a potential physiological activator of TGF-beta1. The inter-alpha-trypsin inhibitor (IalphaI) family of serum protease inhibitors together with tumor necrosis factor-stimulated gene 6 (TSG-6) recently have been implicated in the regulation of this protease pathway. The aim of the current study was to examine PTC synthesis of these proteins and to relate it to alterations of plasmin-protease activity.

METHODS

PTCs were grown to confluence and stimulated under serum-free conditions with either interleukin-1beta (IL-1beta) or 25 mmol/L D-glucose. Alterations in IalphaI and TSG-6 generation were detected by Western analysis of both membrane extracts and supernatant samples. Alterations in gene expression were examined by reverse transcription-polymerase chain reaction. The effect of alteration in synthesis of TSG-6 on plasmin activity was determined by quantitating plasmin inhibitory activity of supernatant samples by in vitro calorimetric assay prior to and following TSG-6 immunoprecipitation.

RESULTS

The data demonstrate that human PTCs constitutively express mRNA for bikunin and heavy chain 3 (H3) of IalphaI. Neither IL-1beta (1 ng/mL) nor 25 mmol/L D-glucose influenced their mRNA expression nor protein synthesis. In contrast, the addition of either IL-1beta or 25 mmol/L D-glucose increased TSG-6 mRNA expression. This was accompanied by an early up-regulation of TSG-6 protein expression following IL-1beta stimulation (24 h) and a late up-regulation after the addition of 25 mmol/L D-glucose (96 h) in the cell culture supernatant and associated with the cell membranes. Early induction of TSG-6 mRNA by IL-1beta was unaffected by the addition of the protein synthesis inhibitor cycloheximide. In contrast, the later glucose-stimulated induction of TSG-6 mRNA was abrogated by the addition of cycloheximide. Stimulation of TSG-6 by either IL-1beta or 25 mmol/L D-glucose was associated with an inhibition of total percentage plasmin activity. Immunoprecipitation of TSG-6 in these samples returned plasmin activity to control levels.

CONCLUSIONS

: The data demonstrate that human PTCs constitutively express the bikunin and H3 components of the IalphaI family of serum protease inhibitors. Moreover, the addition of IL-1beta or 25 mmol/L D-glucose up-regulates the expression of TSG-6 in these cells, resulting in an inhibition of plasmin activity.

Long-term persistence of monoclonal B cells after cure of Helicobacter pylori infection and complete histologic remission in gastric mucosa-associated lymphoid tissue B-cell lymphoma

PURPOSE

Cure of Helicobacter pylori infection is associated with remission induction in the majority of patients with low-grade gastric mucosa associated lymphoid tissue (MALT) lymphoma in localized stages; however, limited data exist as to whether these patients may be cured of their lymphoma. The present study was performed to investigate whether the polymerase chain reaction (PCR) for the rearranged immunoglobulin heavy chain region may be used to define "molecular" remission.

PATIENTS AND METHODS

Ninety-seven patients who suffered from low-grade gastric MALT lymphoma stage I(E) were observed with central pathology and molecular biology after cure of H pylori infection. PCR was performed with the use of consensus primers for the framework regions 1, 2, and 3 and monoclonality was corroborated by sequence analysis. In selected cases, microdissection was performed to study the origin of the monoclonal B cells.

RESULTS

Of the 97 patients, 77 obtained complete endoscopic and histologic remission (CR). Twenty of 44 patients with PCR monoclonality at diagnosis and with sufficient molecular follow-up displayed monoclonal bands for a median time of 20.5 months after CR (range, 0 to 50.4 months). These B cells were related to the original lymphoma clone by sequence analysis. Microdissection analysis identified basal lymphoid aggregates as the source of these monoclonal B cells. Local relapse occurred in and was observed by PCR in four patients. All four patients displayed monoclonal PCR before relapse, and three of these four showed ongoing PCR monoclonality throughout their course, indicating the persistence of malignant cells.

CONCLUSION

Half of all patients with gastric MALT lymphoma show long-term PCR monoclonality up to several years after cure of H pylori infection and CR. Patients with monoclonal PCR should be observed closely, whereas long-term PCR negativity may indicate cure of the disease.

Transferrin but not albumin mediates stimulation of complement C3 biosynthesis in human proximal tubular epithelial cells

Complement is increasingly implicated in the pathogenesis of progressive renal disease resulting from persistent proteinuria. We have previously shown that apical serum proteins stimulate C3 in cultured human proximal tubular epithelial cells (PTECs), and that the stimulant is a nonalbumin compound of 30 to 100 kd. We postulated in this study that transferrin and apotransferrin, also important components of proteinuric urine in this molecular-weight range, might be the culprit. Human PTECs were obtained by differential sieving of renal cortical tissue from the normal pole of tumor nephrectomy specimens and characterized to be predominantly of proximal tubular origin. Complement C3 messenger RNA (mRNA) expression was analyzed in confluent growth-arrested PTEC monolayers in media containing different concentrations (2.5 to 20 mg/mL) of transferrin by reverse transcription and polymerase chain reaction. Pure human albumin was used as a control protein. C3 protein secretion was detected and quantified by a sandwich enzyme-linked immunosorbent assay on cell culture supernatants after distinct time points. Transferrin enhanced the rate of C3 secretion in a dose-dependent manner, reaching maximal stimulation at doses of 10 mg/mL. Selected experiments using the Transwell technique showed that C3 release was predominantly apical in the resting state. The addition of 10 mg/mL of transferrin apically but not basolaterally stimulated both apical and basolateral C3 secretion and increased the basolateral-apical ratio of C3 secretion from 0.45 +/- 0.16 to 0.93 +/- 0.24 (P: < 0.02). Constitutive C3 mRNA expression was upregulated by transferrin in a time- and dose-dependent fashion, reaching a peak after 24 hours. A similar degree of C3 upregulation was reproduced when iron-poor transferrin, apotransferrin, was used instead. These results indicate that C3 synthesis in PTECs is upregulated by transferrin, for which protein rather than iron moiety may account for the observed effects. These findings provide evidence linking proteinuria with overexpression of tubular complement.

Alterations on chromosome 3 in endemic and nonendemic nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is endemic in parts of southern China and is etiologically associated with Epstein-Barr virus (EBV) infection as well as other dietary and environmental factors. Loss of heterozygosity (LOH) on chromosome 3p has been described in NPC from the endemic region. In this study, tumors originating from both the NPC nonendemic area of northern China and the endemic area in southern China were analyzed for LOH at 8 microsatellite markers on chromosome 3. Allele loss was detected at D3S1300 in 3p14.2 in more than 50% of tumors from both the endemic and nonendemic areas, suggesting that LOH at this locus probably does not account for the endemicity of NPC in southern China. The 3p14.2 region encompasses FHIT, a candidate tumor suppressor gene previously shown to be rearranged in several NPC cell lines. In this study, analysis of FHIT gene structure and transcription in primary tumors did not support a role for FHIT in NPC. However, the high frequency of allele loss at 3p14.2 in NPC from endemic and nonendemic regions supports the possibility that an important tumor suppressor gene other than FHIT complements EBV transformation and resides in this region.

Interaction of Fusarium graminearum and F. moniliforme in Maize Ears: Disease Progress, Fungal Biomass, and Mycotoxin Accumulation

ABSTRACT To investigate the interaction between two major ear-rotting pathogens, maize ears were inoculated with either Fusarium graminearum, F. moniliforme, or an equal mixture of the two. Silk and kernel tissues were periodically harvested throughout the growing season so that a time course of the experimental variables (disease severity, ergosterol content, fungal DNA content, and mycotoxin concentration) could be recorded. Over the 3 years tested (1992 to 1994), the highest levels of disease and ergosterol were found in the F. graminearum treatment, followed by the mixture treatment (F. graminearum plus F. moniliforme) and, finally, the F. moniliforme treatment. Kernel ergosterol content and disease rating were correlated for both pathogens, but the highest correlation coefficients were obtained in the F. graminearum treatment. The DNA analysis revealed that, in the mixed inoculum, F. moniliforme had a greater growth rate than did F. graminearum. In 1994, appreciable F. moniliforme from natural inoculum was found in the F. graminearum treatment. Fumonisin B(1) levels did not differ between the F. moniliforme treatment and the mixed inoculum treatment. The effect of temperature on the growth rate of the two species explained some of the field results, with temperatures in the silks being more favorable to F. moniliforme. Data on the growth rate on silks obtained by the incorporation of radiolabeled precursor to ergosterol demonstrated that F. graminearum was able to grow well at 26 to 28 degrees C, whereas F. moniliforme grew well over a broader range, including at higher temperatures.

TGF-beta1 stimulates the release of pre-formed bFGF from renal proximal tubular cells

BACKGROUND

It is now clear that the progression of renal disease is closely correlated to the degree of renal interstitial fibrosis. We have previously demonstrated that the renal proximal tubular epithelial cell may contribute to the fibrotic response by the generation of profibrotic cytokines. Transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) are two of a group of profibrotic cytokines that have been associated with the development of renal interstitial fibrosis. In this study, we have examined the influence of TGF-beta1 on the generation of bFGF by renal tubular epithelial cells.

METHODS

HK2 cells were grown to confluence and were serum deprived and stimulated with recombinant TGF-beta1 under serum-free conditions. Subsequently, supernatant, cell-associated, intracellular, and matrix-associated bFGF concentrations were determined by enzyme-linked immunosorbent assay (ELISA). bFGF mRNA expression was examined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The exposure of confluent serum-deprived HK2 cells to TGF-beta1 led to a significant increase in bFGF concentration in the cell culture supernatant. Twenty-four hours following the addition of 10 ng/ml TGF-beta1, this represented a twofold increase in bFGF concentration (control, 102 pg/ml, N = 24, vs. 202 pg/ml, N = 19, P = 0.0001). Despite the increase in bFGF concentration in the supernatant, there was no change in the expression of bFGF mRNA following the addition of TGF-beta1. The addition of 10 ng/ml of TGF-beta1 led to a 30% decrease in the total cell-associated bFGF concentration (control, 8.51 ng/ml, N = 16, TGF-beta1, 6.01 ng/ml, N = 13, P = 0.0042). This decrease in intracellular bFGF was associated with a 15% reduction in anti-bFGF antibody binding to fixed permeabilized cells, following the addition of 10 ng/ml of recombinant TGF-beta1 (N = 9, P = 0.0007), suggesting that the mechanism of stimulation of bFGF by TGF-beta1 involved the release of preformed bFGF from within the cells. In addition, following the addition of TGF-beta1, there was a significant dose-dependent decrease in the amount of bFGF sequestered in the extracellular matrix. At a dose of 10 ng/ml TGF-beta, this represented a greater than sevenfold decrease (N = 9, P = 0.0007) in matrix-bound bFGF, although this represented less than 3% of the total bFGF released into the supernatant.

CONCLUSION

The data presented suggest that the main mechanism by which TGF-beta1 stimulates bFGF generation by proximal tubular epithelial cells is by stimulation of the secretion of preformed cytokine from within the cells.

Quantitative polymerase chain reaction assay for DNA repair within defined genomic regions

We have developed a quantitative assay to determine repair of structurally different DNA lesions at defined genomic sites. This assay depends on the fact that many different types of damage are repaired by the same nucleotide excision repair (NER) pathway which includes synthesis of short DNA fragments at the sites of damage. After exposure to damaging agents, cells are treated with 5-bromodeoxyuridine (BrdUrd) to label the regions undergoing repair with the presumption that regions that have been more efficiently repaired would incorporate more BrdUrd than regions that were less effectively repaired. Thus, the abundance of the different sequences in the BrdUrd-containing DNA would be a direct and quantitative measure for the repair rates of the corresponding regions. The BrdUrd-containing, repaired DNA was isolated by CsCl gradient centrifugation and immunoprecipitation with anti-BrdUrd antibody and was used as template in quantitative PCR in which the amount of the product was directly proportional to the amount of template. This approach was used to address the question whether DNA repair after UV-irradiation occurs in an uniform, random manner or with preferences for certain regions. We found out that there was a higher repair efficiency at the 5'-end of the mouse gamma-globin domain in Ehrlich ascites tumor cells.

Exposure of human renal proximal tubular cells to glucose leads to accumulation of type IV collagen and fibronectin by decreased degradation

Thickening and reduplication of the tubular basement membrane has been reported as an early event in diabetic nephropathy. In the current study we examined the effects of elevated D-glucose concentrations on human proximal tubular (HPTC) type IV collagen and fibronectin turnover. Incubation of confluent growth arrested HPTC with 25 mM D-glucose led to accumulation of both type IV collagen and fibronectin. This effect was maximal at 48 hours and represented a sevenfold increase for fibronectin (N = 4, P = 0.04), and a threefold increase for type IV collagen (N = 3, P = 0.03) over cells exposed to 5 mM D-glucose controls. This increase was not dependent on new gene transcription for either protein. Tissue inhibitor of metalloproteinases (TIMP 1 + TIMP 2) were induced following addition of 25 mM D-glucose, but not when cells were exposed to 5 mM D-glucose. Twenty-four hours after the addition of 25 mM D-glucose there was an eightfold increase in TIMP 1 (P = 0.009, N = 4), and a tenfold increase in TIMP 2 levels (P = 0.003, N = 4), over the control values for both inhibitors. The increase in both TIMP 1 and TIMP 2 in response to 25 mM D-glucose was abrogated in a dose dependent manner by the aldose reductase inhibitor sorbinil. Gelatin-substrate gel zymography showed increased activity of gelatinase A, but not of gelatinase B in response to the addition of 25 mM D-glucose to HPTC. The induction of gelatinase A was accompanied by increased gelatinase A mRNA expression, which was inhibited both by protein kinase C (PKC) depletion using PMA pre-treatment, and by the addition of a PKC inhibitor. These data demonstrate that the glucose-induced accumulation of type IV collagen and fibronectin is unrelated to increased gene transcription, but may involve alterations in the degradative pathway of these basement membrane constituents. Furthermore, the data demonstrate that glucose may simultaneously activate two intracellular pathways (the polyol pathway and a PKC dependent activation pathway), which are involved in mediating separate, complementary effects on cell function.

Cure of Helicobacter pylori infection and duration of remission of low-grade gastric mucosa-associated lymphoid tissue lymphoma

BACKGROUND

Low-grade B-cell lymphomas arising in mucosa-associated lymphoid tissue (MALT) are most frequently localized in the gastrointestinal tract. More than 90% of gastric MALT lymphomas are diagnosed in patients with chronic, Helicobacter pylori-associated gastritis. High remission rates for these lymphomas have been observed after the cure of H. pylori infection. Data are lacking, however, with regard to the duration of the remissions. To address this question of remission duration, we have followed 50 patients in whom H. pylori infections were eradicated, and we determined whether the patients in complete remission displayed evidence of residual monoclonal B cells during follow-up.

METHODS

Patients were treated with amoxycillin and omeprazole for 2 weeks in an attempt to cure H. pylori infections. Follow-up included endoscopic investigations with biopsy sampling. Monoclonal B cells in biopsy specimens were detected by means of a polymerase chain reaction (PCR)-based assay.

RESULTS

H. pylori infections were cured in all 50 patients. The median follow-up for the 50 patients is currently 24 months (729 days; range, 135-1411 days). Forty patients achieved complete remission of their lymphomas, but five have subsequently relapsed. The median time of continuous complete remission for the 40 patients was 15.4 months (468 days; range, 0-1198 days). Among six patients whose Iymphomas did not respond to H. pylori eradication, four revealed high-grade lymphomas upon surgery. PCR indicated the presence of monoclonal B cells during follow-up in 22 of 31 assessable patients in complete remission.

CONCLUSIONS

Complete remissions of low-grade gastric MALT Iymphomas after the cure of H. pylori infection appear to be stable, although most patients display evidence of monoclonal B cells during follow-up. Whether these patients are truly cured of their Iymphomas remains to be determined.

Potentiation of interferon-induced indoleamine 2,3-dioxygenase mRNA in human mononuclear phagocytes by lipopolysaccharide and interleukin-1

Previous studies have shown that interleukin-1 (IL-1) enhances interferon (IFN)-gamma-induced indoleamine 2,3-dioxygenase (IDO) enzymatic activity in human monocyte-derived macrophages by increasing expression of IDO mRNA. The objectives of this study were to see if IL-1 also enhances IFN-beta-induced IDO activity by increasing specific mRNA expression and to determine if lipopolysaccharide (LPS) enhances IFN-induced IDO activity in a similar manner. Macrophages were treated with combinations of IFN-beta or IFN-gamma as inducer and LPS or IL-1 as potentiator. After 48 h, IDO mRNA expression was assessed by RT-PCR, and IDO activity was determined by HPLC. LPS alone induced IDO mRNA expression and also increased IDO mRNA expression induced by either type of IFN. Furthermore, IL-1 enhanced IFN-beta-induced IDO mRNA expression. When IDO mRNA was assessed 6 h after treatment, mRNA was detected at concentrations of IFNs or potentiator or both in which enzymatic activity at 48 h was undetectable. Thus, although the mechanism of potentiation of IFN-induced IDO by LPS and by IL-1 involves increased expression of IDO mRNA, it appears that temporal differences in IDO mRNA expression are also important.

The status of p53 in the metastatic progression of colorectal cancer

In order to investigate the role of TP53 in tumour progression and metastasis, we analysed 33 liver metastases of colorectal carcinomas and 19 primary colon carcinomas from the same hospital with respect to mutational changes, loss of heterozygosity and expression of the TP53 tumour suppressor gene. Direct sequencing of PCR products corresponding to the coding region of TP53 revealed that 13 of 19 primary tumours (68%) and 23 of 33 liver metastases (70%) had mutations in the TP53 gene. The distribution of mutations along the coding region of TP53 was similar in liver metastases compared to primary tumours. Thus, codon specificity did not seem to be a relevant factor and cells carrying specific TP53 mutations seem to have no selective advantage in the metastasising process. Comparing our data with the mutational spectra found in other countries did not reveal differences in the distribution of mutations along the coding region. Most of the metastases analysed showed loss of heterozygosity (LOH, 9 of 12 cases, 75%) and strong nuclear staining in immunohistochemistry (10 of 17 cases, 59%). Furthermore, with respect to mRNA expression levels, tumours carrying TP53 mutations showed significantly higher p53 mRNA levels compared to those without TP53 mutations. Thus, regulation of p53 mRNA levels seems to be subject to selection processes in tumourigenesis.

MPN-PCR-quantification method for staphylococcal enterotoxin c1 gene from fresh cheese

PCR detection methods have been extensively used in diagnostic microbiology. However, a lack of a simple and reliable method for quantification of the PCR products has partly hindered the use of PCR in routine food laboratories. The quantification of PCR products can be done by combining the principles of MPN statistics and PCR technique. We have developed a simple and sensitive MPN-PCR assay for detection and enumeration of enterotoxin C producing Staphylococcus aureus NCTC 10655 from fresh cheese. By amplifying single copy chromosomal enterotoxin C gene fragment, we could detect as little as 20 cfu/g. By Moran's test, most of the DNA dilution series appeared to fulfill the basic mathematical assumptions of ordinary MPN methods. The analysis with MPN-PCR took one day to perform compared with three days analysis time with plate counting. This MPN-PCR method can be readily applied with different primer systems without extensive development work.

Polarity of stimulation and secretion of transforming growth factor-beta 1 by cultured proximal tubular cells

Proximal tubular epithelial cells are the most abundant cells in the renal cortex, and recent studies suggest that they may play an important role in initiating pathological changes in renal disease. Transforming growth factor (TGF)-beta 1 has been implicated as a major factor controlling the development and progression of renal fibrosis in numerous diseases, including diabetic nephropathy. We have recently demonstrated that human proximal tubular epithelial cells synthesize and secrete TGF-beta 1 after the sequential addition of both 25 mmol/L D-glucose and platelet-derived growth factor (PDGF). The present study examines the control of this synthesis and in particular the polar requirements of the stimulation and the direction of release of the protein. A proximal tubular cell line (LLC-PK1) was cultured on porous tissue culture inserts. Confluent cells were exposed to 25 mmol/L D-glucose on either their apical or basolateral aspect. TGF-beta 1 mRNA induction (reverse transcriptase polymerase chain reaction) occurred only after basolateral exposure. Similarly, TGF-beta 1 synthesis and secretion was induced only by the subsequent addition of PDGF to the basolateral aspect of the cells. In contrast, TGF-beta 1 protein secretion was detected equally in the apical and basolateral compartments. This effect was maximal after 12-hour PDGF stimulation and represented a threefold increase over controls for TGF-beta 1 in both the apical and basolateral compartments (n = 3, P < 0.05 versus control). The glucose transporter inhibitors phlorizin and phloretin were used to investigate the role of specific D-glucose transport proteins. Application of either basolateral phlorizin or phloretin at the time of addition of 25 mmol/L D-glucose to the same compartment inhibited TGF-beta 1 synthesis in response to PDGF. Maximal inhibition was achieved at 0.5 mmol/L of either inhibitor (phlorizin percent inhibition of apical TGF-beta 1, 75%, P = 0.015, and of basolateral TGF-beta 1, 78%, P = 0.015; phloretin percent inhibition of apical TGF-beta 1, 68%, P = 0.03, and of basolateral TGF-beta 1, 79%, P = 0.001, n = 5, P versus control). No inhibition was seen with apical application of either inhibitor. These data demonstrate that the priming of proximal tubular cells for TGF-beta 1 synthesis occurs only after basolateral exposure of the cells to 25 mmol/L D-glucose. This mechanism is dependent on the activity of the basolateral D-glucose transporter GLUT-1. In another series of experiments, TGF-beta 1 synthesis in response to the addition of basolateral PDGF was also induced after basolateral pretreatment with D-galactose but not 2-deoxy-D-glucose. This priming effect demonstrates the dependence of this response on glucose metabolism by the cells, not simply the activity of the GLUT-1 transporter, as both 2-deoxy-D-glucose and D-galactose are transported by GLUT-1, although only the latter is metabolized. The extrapolation of these results to diabetic nephropathy would suggest that it is changes in the interstitial concentration of glucose rather than the urinary glucose level that likely modulate the synthesis of the profibrotic cytokine TGF-beta 1 and thereby influence the progression of interstitial fibrosis.

Functional aspects of apoptosis in hematopoiesis and consequences of failure

Apoptosis is an internally directed, physiological method of cell destruction. Cellular components are dismantled within the confines of an intact cell membrane, and rapid ingestion by phagocytic cells prevents local inflammation. A variety of genes have now been identified as positive or negative regulators of apoptosis. Transfection experiments and studies of gene cooperation in viral transformation suggest that full cellular transformation requires not only the deregulation of proliferation, but also the inhibition of concomitant apoptosis programs. The regulation of apoptosis is fundamental to hematopoietic homeostasis. Stem cell renewal is continuously counterbalanced by apoptosis in functionally inactive or terminally differentiated cells. Extensive cell death in developing lymphocyte populations ensures that only cells recognizing non-self antigens are released into the periphery, and the finite lifespan of terminally differentiated cells enables the extensive cell turnover demanded by functional aspects of the hematopoietic system. The requirement of each hematopoietic sub-population for a specific sub-set of survival factors, provides a flexible mechanism for dictating the cellular composition of the mature population and for controlling population size. Surplus cell production and apoptosis are therefore normal features of hematopoiesis. The consequences of deregulated apoptosis are severe. Excessive apoptosis in lymphocyte populations plays a major role in the pathogenesis of acquired immunodeficiency syndrome (AIDS), whereas ineffective apoptosis has been associated with the development of inflammation, autoimmunity and hematological malignancies. The identification of various genetic abnormalities which influence apoptosis in leukaemic cells (e.g., mutant p53, Bcr-Abl and over-expression of Bcl-2), suggests that the acquisition of an anti-apoptotic lesions is an important event in the multi-step evolution of hematological malignancies. In addition, the nature of some leukaemias particularly the chronic leukemias, in which the leukemic cells are nonproliferative and long lived, suggests that anti-apoptotic lesions are early events in the pathogenesis of these diseases. It is likely that the utilization of mechanisms to evade apoptosis would facilitate disease progression in all leukemias and contribute to the development of multi-drug resistance. A better understanding of apoptosis mechanisms in hematopoietic cells, and their exploitation by leukemic cells should be useful in the development of improved cytotoxic regimes.

Induction of TGF-beta 1 synthesis in D-glucose primed human proximal tubular cells by IL-1 beta and TNF alpha

The aim of the present study was to examine whether the induction of TGF-beta 1 synthesis by the pro-inflammatory macrophage derived cytokines, IL-1 beta or TNF alpha, was modified by alterations in D-glucose concentrations. Stimulation of growth arrested HPTC with IL-1 beta or TNF alpha resulted in increased expression of TGF-beta 1 mRNA. The transcript was demonstrable 60 minutes after the addition of IL-1 beta, and apparent steady-state mRNA levels were achieved after six hours. Following stimulation with TNF alpha, TGF-beta 1 mRNA was detectable after 15 minutes and reached steady state levels by two hours. Quantitative RT-PCR revealed that following six hours stimulation with either IL-1 beta or TNF alpha (both at 1 ng/ml), there was no difference in the absolute amount of TGF-beta 1 mRNA induced by these two stimuli (14.8 +/- 5.6 vs. 19.7 +/- 4.9 PM). Despite induction of TGF-beta 1 mRNA following stimulation with IL-1 beta or TNF alpha, neither stimulus increased TGF-beta 1 protein synthesis or release. Pre-exposure of HPTC to 25 mM D-glucose for 48 hours and subsequent stimulation with IL-1 beta resulted in the secretion of latent TGF-beta 1 in both a time and dose dependent manner. This effect was not apparent following TNF alpha stimulation of D-glucose primed HPTC. Stimulation of TGF-beta 1 synthesis by IL-1 beta in D-glucose primed cells was inhibited by cycloheximide but not by actinomycin-D. Examination of D-glucose induced TGF-beta 1 mRNA revealed that IL-1 beta, but not TNF alpha, increased the stability of the D-glucose induced transcript. These results demonstrate that the interaction of D-glucose and IL-1 beta lead to secretion of TGF-beta 1 by HPTC. In contrast, such an interaction was not demonstrable between D-glucose and TNF alpha. This may be explained by the ability of IL-1 beta to stabilize D-glucose-induced TGF-beta 1 mRNA.

Quantification of Bcr-Abl transcripts in chronic myelogenous leukemia (CML) using standardized, internally controlled, competitive differential PCR (CD-PCR)

The quantification of Bcr-Abl transcript numbers in chronic myelogenous leukemia (CML) patients described here uses simultaneous competitive PCR amplification of the target gene (Bcr-Abl) and a reference gene (porphobilinogen deaminase; Pbgd) together with a single composite competitor molecule for both targets based on heterologous sequences. Using this technique, Bcr-Abl transcript numbers could be reproducibly determined even in clinical samples known to harbour poor quality RNA.

Fluid resuscitation attenuates early cytokine mRNA expression after peritonitis

OBJECTIVE

To study the hypothesis that fluid resuscitation alters cytokine gene expression after experimental murine peritonitis.

MATERIALS AND METHODS

Mice underwent cecal ligation and puncture (CLP) to induce peritonitis and were randomized to receive variable amounts of normal saline (0, 0.25, 1.0 ml. subcutaneously) and serum (0 or 0.1 mL) after operation. Hepatic and small intestinal (ileal) tissue were harvested at 3 or 6 hours after CLP, and total tissue RNA was extracted. Reverse transcriptase polymerase chain reaction was used to provide relative quantitation of tumor necrosis factor-alpha and interleukin (IL)-1 beta messenger RNA (mRNA) compared with beta-actin.

RESULTS

CLP without resuscitation resulted in significant increases in hepatic tumor necrosis factor-alpha mRNA (1190% at 6 hours compared with normal animals), and IL-1 beta mRNA (1475%), and intestinal IL-1 beta mRNA (1243%). Volume administration attenuated cytokine expression at both 3 and 6 hours, and saline seemed to have more potent effects than serum. The volume of resuscitation correlated with survival at 18 hours. Survival in the saline (1 mL) + serum group was 90% at 18 hours compared with 20 to 40% in the groups with little or no resuscitation. Overall, there were no survivors at 30 hours.

CONCLUSIONS

Fluid resuscitation (amount, composition, timing) should be an important consideration in the utilization of experimental infection models. Furthermore, optimization of the patient's intravascular volume status during sepsis may have important effects on immune responses, in addition to improving hemodynamic variables.

Physical and functional sensitivity of zinc finger transcription factors to redox change

Redox regulation of DNA-binding proteins through the reversible oxidation of key cysteine sulfhydryl groups has been demonstrated to occur in vitro for a range of transcription factors. The direct redox regulation of DNA binding has not been described in vivo, possibly because most protein thiol groups are strongly buffered against oxidation by the highly reduced intracellular environment mediated by glutathione, thioredoxin, and associated pathways. For this reason, only accessible protein thiol groups with high thiol-disulfide oxidation potentials are likely to be responsive to intracellular redox changes. In this article, we demonstrate that zinc finger DNA-binding proteins, in particular members of the Sp-1 family, appear to contain such redox-sensitive -SH groups. These proteins displayed a higher sensitivity to redox regulation than other redox-responsive factors both in vitro and in vivo. This effect was reflected in the hyperoxidative repression of transcription from promoters with essential Sp-1 binding sites, including the simian virus 40 early region, glycolytic enzyme, and dihydrofolate reductase genes. Promoter analyses implicated the Sp-1 sites in this repression. Non-Sp-1-dependent redox-regulated genes including metallothionein and heme oxygenase were induced by the same hyperoxic stress. The studies demonstrate that cellular redox changes can directly regulate gene expression in vivo by determining the level of occupancy of strategically positioned GC-binding sites.

The reliability of the differential polymerase chain reaction compared to restriction fragment length polymorphism for the detection of gene loss in primary tumors

The loss of genetic information from a number of specific regions of the genome has been documented in human tumors in vivo. To estimate the frequency with which IFN beta 1 gene loss occurs in human gliomas, both restriction fragment length polymorphism (RFLP) analysis and polymerase chain reaction (PCR) amplification, using the IFN-gamma gene as a reference, were used and the results obtained with the two methods were compared. The relative intensity of PCR bands (IFN beta 1/IFN gamma) in the gliomas with loss of heterozygosity for the IFN beta 1 was significantly different (P < 0.05) with regard to the gliomas with the IFN beta 1 gene. Consequently, these findings indicate that differential PCR is a reliable and non-radioactive method of demonstrating gene loss in tumors.

Detection of c-myc oncogene amplification in a CML blastic phase patient with double minute chromosomes

Double minute chromosomes (dmin) are relatively rare in leukemias. Cytogenetic analysis of blood cells from a woman with blastic phase chronic myelogenous leukemia (BC-CML) showed numerous dmin chromosomes and complex abnormalities including a Philadelphia (ph(1))-chromosome. Oncogene amplification in hematopoietic malignancies is also rare. Using PCR, we retrospectively investigated the extent of c-myc gene amplification in DNA extracted from stored blood smears from the patient. To qualify the PCR products, the beta-globin gene was used as the internal reference gene and it was co-amplified with the c-myc gene. The extent of amplified c-myc was about 6.8-fold. This finding suggests that the c-myc gene was amplified in dmin and that the gene amplification contributes to the progression to acute leukemia or rapid growth of leukemic cells.

Aberrant FGF-2, FGF-3, FGF-4 and C-erb-B2 gene copy number in human ovarian, breast and endometrial tumours

The important role of oncogene amplification and tumour suppressor gene deletion in human tumours is becoming increasingly apparent. However, extensive screening of human tumours is required before the prognostic significance of such genetic abnormalities can be fully appreciated. The present investigation describes a rapid non-radioactive and largely automated procedure for the analysis of aberrant gene copy number in large numbers of tissue samples of different human tumours. This procedure is based on the sequential use of the polymerase chain reaction (PCR) and high performance ion exchange liquid chromatography (HPIEX). Using this rapid PCR/HPIEX technique, we have identified amplification and deletion of the FGF-2 gene and the FGF-3, FGF-4 and c-erb-B2 oncogenes in human tumours of the breast, ovary and endometrium. Comparison of the data with tumour pathology has revealed possible associations between aberrant gene copy number and tumour type, invasiveness and metastases.

Molecular and immunohistochemical study of class I growth factor receptors in squamous cell lung carcinomas

The class I growth factor receptor family includes epidermal growth factor receptor, i.e. c-erbB-1, c-erbB-2 and c-erbB-3 molecules. These receptors have a significant sequence homology and play an important role in cell growth and differentiation. To further investigate their implication in squamous cell lung carcinomas (SqCLCs), we studied the protein expression by immunohistochemistry and examined for possible gene amplification by a novel semi-quantitative differential polymerase chain reaction (DPCR) technique. Expression of c-erbB-1, c-erbB-2 and c-erbB-3 was present in 65%, 28% and 10% respectively, of 40 SqCLCs cases. Seven of the 11 cases that expressed c-erbB-2, as well as all 4 c-erbB-3 expressing cases, also stained with the anti-c-erbB-1 mAb. Expression of c-erbB-1, but not of c-erbB-2 or c-erbB-3, correlated with the grade of tumor differentiation (100%, 64% and 36% positive cases of well, moderately and poorly differentiated cases respectively, p < 0.003). In addition, c-erbB-1 expression correlated with the presence of regional lymph node metastases within the moderately differentiated group. The c-erbB-1 gene was amplified in 11/40 (28%) cases, all of which overexpressed c-erbB-1 protein, while c-erbB-2 gene amplification was detected in only one case. There was no c-erbB-3 gene amplification in any of the 40 SqCLCs cases. These findings suggest that c-erbB-1, c-erbB-2 and c-erbB-3 receptors do not have a common role and are of different physiological importance, at least at the stage of clinically overt tumor in human SqCLCs.

Human herpesvirus type 7 in blood donors: detection by the polymerase chain reaction

In order to evaluate the prevalence of human herpesvirus type 7 (HHV-7) in adult blood donors oral lavage fluid, buffy coat, and urine samples from 112 persons were examined by the polymerase chain reaction (PCR) at one time point. In addition, 11 donors were studied longitudinally over 11 weeks. When the results of the initial and the longitudinal study were combined HHV-7 DNA was found in samples from 109 of 112 (97.3%) adult blood donors. On the basis of different sensitivity levels of the first and the nested PCR differences were detected in the viral DNA load in the samples. It was found that lavage fluid regularly carried significantly higher DNA concentrations than buffy coat. Out of 112 donors, 102 (91.1%) and 8 (7.1%) were positive in the first, less sensitive PCR in lavage fluid and buffy coat, respectively (P < .0001). After nested PCR, 107 (95.5%) and 74 (66.1%) were positive in lavage fluid and buffy coat, respectively (P < .0001). Urine samples were found positive only sporadically. The longitudinal study showed that the oral lavage fluid of most of the donors consistently carried HHV-7 over up to 53 weeks, whereas buffy coat samples were positive less often. In conclusion, HHV-7 is found frequently in adult blood donors in the oral lavage fluid and buffy coat, which are, therefore, potential sources of HHV-7 transmission.

Molecular study of the interferon genes in chronic myeloid leukemia

The interferons alpha, beta, and w (IFNA, IFNB, IFNW), are a family of genes that have been mapped on the short arm of chromosome 9 (9p21-22). Deletions of genetic material on 9p are frequently observed in hematological diseases, particularly in lymphoid neoplasias. In this paper we have performed the molecular studies of IFNA and IFNB genes in chronic myeloid leukemia (CML) in order to determine if the deletions of these genes are prevalent in this pathology. Forty CML patients, Philadelphia positive or with BCR/ABL rearrangement, were studied at diagnosis. The analysis of IFNA and IFNB genes was performed by Southern and dot blot techniques. Homozygous or hemizygous deletions of IFNA and IFNB genes could not be detected, indicating that deletions of these genes would not be present or would be a very infrequent event in the chronic phase of the CML patients.

Elevated D-glucose concentrations modulate TGF-beta 1 synthesis by human cultured renal proximal tubular cells. The permissive role of platelet-derived growth factor

Interstitial fibrosis is a marker of progression of renal impairment in diabetic nephropathy. Transforming growth factor (TGF)-beta 1 is one of a group of pro-fibrotic cytokines and growth factors that have been associated with the development of interstitial fibrosis. We have examined the modulating influence of glucose on the production of TGF-beta 1 by cultured human proximal tubular cells. Incubation of growth-arrested human proximal tubular cells (HPTC) (72 hours in serum free medium) in 25 mmol/L D-glucose resulted in increased expression of TGF-beta 1 mRNA (as assessed by reverse transcription polymerase chain reaction). This was apparent after 6 hours and increased up to 120 hours exposure. TGF-beta 1 secretion, however, as measured by specific enzyme-linked immunoassay, was unaffected by exposure to 25 mmol/L D-glucose. Sequential stimulation of HPTC, first with 25 mmol/L D-glucose for 48 hours and then with platelet-derived growth factor (PDGF) isoforms, resulted in a dose-dependent secretion of TGF-beta 1. Pre-exposure to 5 mmol/L D-glucose or 25 mmol/L L-glucose did not prime for TGF-beta 1 release. At 50 ng/ml PDGF this effect was greatest for the AA isoform (AA 31.4 +/- 7.1, AB 20.98 +/- 8.9, BB 7.8 +/- 2.2, P < 0.05 for all versus control, n = 3, mean +/- SEM ng/10(6) cells/24 hours). These effects were blocked by the addition of antibody to the PDGF alpha-receptor. TGF-beta 1 secretion was inhibited in a dose-dependent manner by pretreatment with cyclohexamide, but was not affected by pretreatment with actinomycin D. Stimulation of HPTC with a single dose of PDGF induced TGF-beta 1 mRNA; however, only after application of a second dose of PDGF (after TGF-beta 1 mRNA induction) did TGF-beta 1 protein secretion occur. We also demonstrated that PDGF stimulation of HPTC induced an inherently more stable TGF-beta 1 mRNA transcript. These findings demonstrate that elevated D-glucose concentration alone is insufficient to lead to increased TGF-beta 1 secretion by HPTC despite increased mRNA expression. However, application of a second stimulus such as PDGF, when TGF-beta 1 mRNA expression is increased, leads to increased protein synthesis and secretion of TGF-beta 1. This implies that elevated glucose concentrations might prime proximal tubular cells for TGF-beta 1 synthesis and thus contribute to the development of interstitial fibrosis.

Regression of primary gastric lymphoma of mucosa-associated lymphoid tissue type after cure of Helicobacter pylori infection. MALT Lymphoma Study Group

Lymphoma of gastric-mucosa-associated lymphatic tissue (MALT) type has been linked to infection with Helicobacter pylori. We investigated the effect on MALT lymphoma of eradicating H pylori infection. 33 patients with primary gastric low-grade MALT lymphoma associated with H pylori gastritis were treated with omeprazole (120 mg daily) and amoxycillin (2.25 g daily) for 14 days to eradicate H pylori. In addition to histology, PCR was used to examine proliferation of monoclonal B cells before treatment and during follow-up. All patients had at least two post-treatment examinations, and all became negative for H pylori, 2 after a second treatment course. On histology, 23 (70%) patients showed complete regression and 4 (12%) partial regression of lymphoma. 6 (18%) patients had no change after cure of H pylori infection. 1 was treated with chemotherapy. Of 5 treated surgically, 4 were found to have high-grade B-cell lymphoma on histology of the resected stomach and 1 a high-grade T-cell lymphoma. PCR showed complete disappearance of monoclonal B cells after cure of H pylori infection in 13 of 16 patients investigated. During median follow-up of 1 year no relapse of MALT lymphoma occurred. Low-grade primary gastric MALT lymphoma can completely regress after eradication of H pylori infection. However, longer follow-up is needed to clarify whether the remission is lasting.

Double-differential PCR for gene dosage estimation of erbB oncogenes in benign and cancer tissues and comparison to cellular DNA content

Competitive and differential quantitative PCR methods circumvent the limiting factors of PCR which cause poor reproducibility. We describe the development and performance evaluation of another quantitative PCR method, double-differential PCR (ddPCR). The ddPCR method comprises the co-amplification of the single-copy gene HBB, the erbB-1, erbB-2 and erbB-3 oncogenes and the second single-copy reference gene SOD2 under equal reaction conditions. The ratio of band intensities of the PCR products in silver-stained polyacrylamide gels expresses the average gene copy number (AGCN) per cell of the erbB oncogenes. The coefficient of variability (CV) was less than 25% for an AGCN of 1. The PCR data were in correlation to the results from dot blotting. DNA image analysis did not reveal any correlation between DNA content and gene dosage deviation of the erbB oncogenes. The method was applied to normal breast tissue, benign breast diseases, breast cancer tissue and lymph node metastases. We suggest this method as being reproducible, low cost and rapid, and therefore suitable for clinical studies on erbB oncogene dosage estimation.

Metalloproteinase generation by human glomerular epithelial cells

In the present study cultured human glomerular epithelial cells (HGEC) were used to examine the potential role for these cells in the turnover of the glomerular basement membrane (GBM) through the secretion of matrix metalloproteinases. The cells were shown by substrate gel electrophoresis to secrete gelatinase activity of molecular weights 72 kDa and 92 kDa. The gelatinolytic activity was inhibited by EDTA (10 mM), and by both TIMP-I and TIMP-II, but was not inhibited by PMSF (2.5 mM), indicating that the enzymes belonged to the metalloproteinase family. The identity of the enzymes was confirmed by the use of specific antisera to gelatinase A and gelatinase B. In addition, reverse transcription polymerase chain reaction (RT PCR) amplification of HGEC mRNA using specific primers to the two enzymes yielded single bands of amplified DNA and served to verify the identity of the enzymes. In supplementary experiments using both specific antiserum and PCR primers it was shown that HGEC express message and secrete both the specific metalloproteinase inhibitors TIMP-I and TIMP-II. These results indicate that the synthesis and secretion of degradative enzymes and their controlling inhibitors by HGEC have the potential to be involved in the turnover of the extracellular matrix.

Expression and mutational analysis of Nm23-H1 in liver metastases of colorectal cancer

It has been proposed that nm23-H1, a candidate suppressor gene for metastasis, plays an important role in metastasis formation of human tumours. In order to investigate its role in the progression of colorectal cancer, we analysed 22 liver metastases of this malignancy with respect to mutational changes, loss of heterozygosity and expression levels of nm23-H1. Although genetic alterations in nm23-H1 have recently been described in those colorectal adenocarcinomas which give rise to distant metastases, we were unable to detect any mutation in the coding sequence of nm23-H1 in the metastatic tissue itself. We further analysed the metastases with respect to allelic deletions at the chromosomal locus of nm23. However, no loss of heterozygosity could be detected in ten informative cases. Moreover, the mRNA expression levels of nm23-H1 in the metastatic tissues were not significantly different from those in normal colon mucosa. Thus, although nm23-H1 might be involved in metastasis suppression of certain tumour types, in colorectal tumour progression its role remains to be determined.

The functional expression of p47-phox and p67-phox may contribute to the generation of superoxide by an NADPH oxidase-like system in human fibroblasts

Recent evidence suggests that a number of non-phagocytic cell types may contain a superoxide generating NADPH oxidase. Studies to data on cultured human fibroblasts have primarily concerned the identification of cytochrome b558, whilst expression of other NADPH oxidase components have not been addressed. In this study we have investigated the expression of NADPH oxidase with particular reference to the cytosolic factors p47-phox and p67-phox. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that human fibroblasts express mRNA for p47-phox, p67-phox and p22-phox. Expression of the gp91-phox transcript was not detected, indicating that human fibroblasts may possess an NADPH oxidase isoenzyme. Western blot analysis of human fibroblast cytosol, using an anti-p47-phox antibody (JW-1), identified a 47 kDa protein. Cell-free reconstitution assays showed that fibroblast cytosol could initiate superoxide generation when mixed with either human fibroblast membranes (0.16 nmol superoxide/min/microgram membrane protein), or resting human neutrophil membranes (0.20 nmol superoxide/min/microgram membrane protein). These data indicate that the expression of p47-phox and p67-phox by human fibroblasts may contribute to the cells' generation of superoxide.

Detection of herpesvirus type 6 by polymerase chain reaction in blood donors: random tests and prospective longitudinal studies

In order to evaluate the prevalence of HHV-6 in blood donors, we examined 112 persons by polymerase chain reaction (PCR) and ELISA. HHV-6 antibodies could be detected in 107/111 (96.4%) of the donors. The median ELISA antibody level was 0.451 (range 0.056-0.914). 14 individuals (12.5%) were PCR positive in either oral lavage fluid, urine or buffy coat. Six persons (5.4%) were PCR positive in buffy coat samples. The prospective longitudinal analysis of 11 donors for periods between 7 and 13 weeks revealed that 4/6 persons who were initially PCR negative had positive tests in 9/63 weeks studied. Two persons were consistently PCR positive over the whole observation period of 12 and 13 weeks. HHV-6 variants could be determined in 14 persons as variant A in nine and variant B in five cases. These observations emphasize the high prevalence of HHV-6 and suggest that some blood donors carry detectable concentrations of the virus and therefore may be a source for transmission of HHV-6. The finding of positive PCR in antibody negative individuals suggests that antibody determination may not be sufficient to identify potentially infectious persons.

Detection of allelic loss within the beta 1-interferon gene in childhood acute lymphoblastic leukemia using differential PCR

Deletion of the short arm of chromosome 9p involving the beta 1-interferon (IFN) gene has been implicated in the process of malignant transformation in lymphomas and acute lymphoblastic leukemias. Since cytogenetic analysis is frequently unsuccessful in clinical samples, we used a recently described differential PCR technique to detect losses within the beta 1-IFN gene in 86 acute leukemias. Using differential PCR, no beta 1-IFN deletion was detected in 44 acute myeloid leukemia (AML) and eight control samples. However, five of 42 acute lymphoblastic leukemia (ALL) probes (12%) exhibited loss of the beta 1-IFN gene (three common ALL, two T-ALL). Cytogenetic analysis was performed independently in three of these five cases and revealed abnormalities of chromosome 9p in two samples. Two of five T-ALL cases exhibited a loss within the beta 1-IFN gene, compared with 3/29 c-ALLs, suggesting a predominance of IFN gene loss in T-ALLs. These data indicate that PCR can be used for rapid detection of gene dosage phenomena in clinical leukemia samples.

Alterations of the p53 gene in Epstein-Barr virus-associated immunodeficiency-related lymphomas

Mutations of the p53 tumor suppressor gene are among the most common genetic alterations found in many different human malignancies, including those of the colon, lung, and breast. Alterations in wild-type p53 lead to loss of the suppressor function and thus contribute to tumorigenesis. The potential role of p53 mutations in a sampling of B-cell lymphomas, the majority of which were associated with Epstein-Barr virus (EBV), was investigated. Twenty-six biopsy specimens from immunocompromised patients, including allograft recipients and patients with AIDS, Wiscott-Aldrich syndrome, and human T-cell leukemia virus type 1 infection, in comparison with three Burkitt lymphomas and four Burkitt lymphoma cell lines were analyzed. Mutation in p53 was detected in all four Burkitt lymphoma cell lines as well as the three Burkitt lymphoma biopsy specimens. In patients with AIDS, 5 of 10 lymphomas were EBV positive, and 1 had a mutation in p53. Mutation in p53 was not detected in 14 EBV-positive lymphomas which arose in transplant recipients. These data indicate that with the exception of Burkitt lymphomas, p53 mutations are not involved in the majority EBV-positive B-cell lymphomas which develop in immunocompromised patients.

Altered expression of the retinoblastoma susceptibility gene in chronic lymphocytic leukaemia

The pathogenesis of chronic lymphocytic leukaemia (CLL) is unknown. One of the most frequent cytogenetic abnormalities in CLL is a deletion within the long arm of chromosome 13, the region to which the retinoblastoma (Rb) gene has been mapped. Lack of Rb expression has been linked to the carcinogenic process in many human tumours. We therefore sought to investigate the role of Rb gene inactivation in CLL using differential polymerase chain reaction on reverse transcribed RNA. The result of the PCR was quantitated using HPLC. 5/39 patients revealed a lack or significantly impaired expression of the Rb gene upon differential PCR analysis. In addition, immunocytochemical studies were performed using the Rb-specific monoclonal antibody PMG245. 10/56 patients showed a weak or absent expression upon immunocytochemical analysis compared to monocytes or granulocytes. The samples lacking Rb were from both early and late stage CLL. Our results indicate that inactivation of the Rb protein occurs in a fraction of CLL cases and can be found in early and late stages of the disease.

Chromosome 9 short arm deletions in malignant diseases

Deletions of 9p21-22, that frequently include the alpha-, beta- and omega-IFN gene cluster, are common in malignant diseases such as acute lymphocytic leukemia, malignant melanoma and malignant glioma. There is also evidence to support the role of a gene(s) on chromosome 9p21 in predisposition for familial malignant melanoma. Although initial studies implicated that the IFN genes could serve as tumor suppressor genes, there is now data, mainly based on estimations of minimum region of overlap for the deletions, indicating that the relevant tumor suppressor gene is located centromeric of the alpha-, beta-, omega-IFN gene cluster.

Molecular alterations in a patient with Turcot's syndrome

Cells of a patient with Turcot's syndrome and of her parents were evaluated for the presence of molecular alterations in the p53 and the Ki-ras gene. Deletions on chromosome 17p, overexpression and point mutations of the p53 gene as well as mutations of the Ki-ras gene were detected in primary and metastatic tumour but not in the germline of the patient nor in her parents.

A novel procedure for quantitative polymerase chain reaction by coamplification of competitive templates

A method is described for the absolute quantification by polymerase chain reaction (PCR) of nucleic acids present in low abundance. The method entails the addition to the sample of competitor DNA molecules that share the same sequence as the amplified target (including primer recognition sites), except for a 20-bp insertion in the middle, which allows easy resolution by gel electrophoresis (competitive PCR). Among the advantages of competitive PCR is that any predictable or unpredictable variable that affects amplification has the same effect on both target and competitor species and that the final ratio of amplified products reflects exactly the initial rate of targets, rendering the reaction independent of the number of amplification cycles. An easy and reliable method for the construction and quantification of competitive templates obtained as recombinant PCR products was developed. The technique was used for the absolute quantification of human genomic DNA with primers from a single copy, subtelomeric region of chromosome 19.