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Biomedical subjects

J Wagner

Publications and source records attributed to J Wagner.

At least 55 records · Page 3Linked to original sources
PubMed2001

Murine embryonic fibroblasts lacking TC-PTP display delayed G1 phase through defective NF-kappaB activation.

Previous results suggested a potential role for T-cell protein tyrosine phosphatase (TC-PTP) in cell proliferation. However, no conclusive data has supported such a function in the modulation of this process. In order to clarify this issue, we isolated TC-PTP-/- murine embryonic fibroblasts (MEFs) as well as cell lines to characterize the role of TC-PTP in the control of cell proliferation and cell cycle. Both TC-PTP-/- primary MEFs and cell lines proliferate slower than TC-PTP+/+ cells. We also demonstrated that TC-PTP-/- cells have a slow progression through the G1 phase of the cell cycle. Further characterization of the G1 defect indicates that the kinetics of cyclin D1 induction was delayed and that p27(KIP1) remains at higher levels for an extended period of time. Moreover, cells lacking TC-PTP showed a delayed activation of CDK2. This slow progression through the early G1-phase resulted in decreased phosphorylation of the RB protein and subsequent delay into the S phase transition. In contrast, no further defects were detected in other phases of the cell cycle. Survey of the potential signaling pathways leading to this delayed cyclin D1 expression indicated that NF-kappaB activation was compromised and that IKKbeta activity was also reduced following PDGF stimulation. Reintroduction of wild-type TC-PTP into the TC-PTP-/- cells rescued the defective proliferation, cyclin D1 expression, NF-kappaB activation as well as IkappaB phosphorylation. Together, these results confirm that TC-PTP plays a positive role in the progression of early G1 phase of the cell cycle through the NF-kappaB pathway.

Animals↗
PubMed2001

Two novel IL-1 family members, IL-1 delta and IL-1 epsilon, function as an antagonist and agonist of NF-kappa B activation through the orphan IL-1 receptor-related protein 2.

IL-1 is of utmost importance in the host response to immunological challenges. We identified and functionally characterized two novel IL-1 ligands termed IL-1delta and IL-1epsilon. Northern blot analyses show that these IL-1s are highly abundant in embryonic tissue and tissues containing epithelial cells (i.e., skin, lung, and stomach). In extension, quantitative real-time PCR revealed that of human skin-derived cells, only keratinocytes but not fibroblasts, endothelial cells, or melanocytes express IL-1delta and epsilon. Levels of keratinocyte IL-1delta are approximately 10-fold higher than those of IL-1epsilon. In vitro stimulation of keratinocytes with IL-1beta/TNF-alpha significantly up-regulates the expression of IL-1epsilon mRNA, and to a lesser extent of IL-1delta mRNA. In NF-kappaB-luciferase reporter assays, we demonstrated that IL-1delta and epsilon proteins do not initiate a functional response via classical IL-1R pairs, which confer responsiveness to IL-1alpha and beta or IL-18. However, IL-1epsilon activates NF-kappaB through the orphan IL-1R-related protein 2 (IL-1Rrp2), whereas IL-1delta, which shows striking homology to IL-1 receptor antagonist, specifically and potently inhibits this IL-1epsilon response. In lesional psoriasis skin, characterized by chronic cutaneous inflammation, the mRNA expression of both IL-1 ligands as well as IL-1Rrp2 are increased relative to normal healthy skin. In total, IL-1delta and epsilon and IL-1Rrp2 may constitute an independent signaling system, analogous to IL-1alphabeta/receptor agonist and IL-1R1, that is present in epithelial barriers of our body and takes part in local inflammatory responses.

Amino Acid Sequence↗
PubMed2001

Synthesis of derivatives of the novel cyclophilin-binding immunosuppressant sanglifehrin A with reduced numbers of polar functions.

The syntheses and the biological activities of 53-deoxo sanglifehrin A (2) and 61-deoxy octahydrosanglifehrin A (3) are described. Compound 2 shows intracellular cyclophilin (CyP)-binding and immunosuppressive activity in the mixed-lymphocyte reaction (MLR) similar to that of sanglifehrin A (1). Compound 3 is much less active in the MLR despite unchanged intracellular CyP-binding. This indicates that the 53-keto group is not necessary for immunosuppressive activity, while the 61 hydroxy group is required.

Animals↗
PubMed2001

Retinoids inhibit the actions of angiotensin II on vascular smooth muscle cells.

Retinoids are derivatives of vitamin A and powerful inhibitors of cell proliferation and inflammation. Angiotensin II (Ang II) contributes to vascular lesions by promoting cell growth of vascular smooth muscle cells (VSMCs). Therefore, we examined whether retinoids interfere with the proproliferative actions of Ang II in VSMCs via AT(1) receptor-dependent or activator protein-1 (AP-1)-dependent mechanisms. VSMCs express retinoid receptor proteins, ie, retinoic acid receptor (RAR) alpha and retinoid X receptor (RXR) alpha. Long-term exposure to 1 micromol/L all-trans retinoic acid (RA) dose-dependently inhibited Ang II-induced cell proliferation (P<0.005) as well as DNA and protein synthesis (P<0.001). All-trans RA blocked Ang II stimulation of transforming growth factor-beta(1) mRNA (P<0.005). All-trans RA inhibition of vascular VSMC growth was mediated both via RAR- and RXR-dependent pathways, as shown by receptor-specific synthetic retinoids. Transfection experiments revealed that inhibition of AP-1-dependent gene transcription is one mechanism by which all-trans RA inhibits Ang II action. RARalpha cotransfection enhanced the anti-AP-1 effects of all-trans RA dose-dependently. AP-1 activity was similarly inhibited by cotransfection with either RARalpha or RXRalpha. Ang II-induced gene expression of c-fos was abrogated by all-trans RA treatment (P<0.005). In VSMCs, all-trans RA downregulated AT(1) receptor mRNA (P<0.01) and reduced B(max) (P<0.001). All-trans RA repressed Ang II-stimulated AT(1) receptor promoter activity. The all-trans RA inhibitory effect was abolished when the AP-1 consensus site on the AT(1) receptor promoter was deleted. Our findings demonstrate that retinoids are potent inhibitors of the actions of Ang II on VSMCs. The findings support the notion that retinoids may interfere with proliferative vascular disease.

Alitretinoin↗
PubMed2001

Efficacy of cationic liposome-mediated gene transfer to mesangial cells in vitro and in vivo.

Mesangial cells represent a major target for gene transfer approaches to the kidney. To establish a liposome-based system for transfection of mesangial cells we analyzed the efficacy and toxicity of different cationic liposomes and other nonviral transfection methods in primary cultures of rat and human mesangial cells using the Escherichia coli beta-galactosidase (lacZ) gene as a marker. In addition, an expression vector containing a human renin cDNA under the control of the cytomegalovirus immediate-early promoter/enhancer was generated, introduced into mesangial cells, and assayed in a system of transient gene expression. In vivo, gene transfer was studied after infusion of liposome/DNA complexes in the kidney of rats via the renal artery. Transfection efficiency ranged from 5.5% with DMRIE Liposomes in rat mesangial cells to 1.1% with LipofectAmine liposomes in human mesangial cells. Cytotoxicity following transfection was dependent on the transfection method. Transfection with the human renin expression vector led to the secretion of 11 pg/10(4) cells/48 h human renin in rat mesangial cells, 3,600 pg/10(4) cells/48 h in 293 cells, and 113 pg/10(4) cells/48 h human renin in opossum kidney cells. In vivo, infusion of liposomes was accompanied by nephrotoxicity and did not result in marker gene expression. Together the data demonstrate that cationic liposomes are useful tools for transferring genes into mesangial cells, including human mesangial cells. Cationic liposomes provide a functional system for the synthesis and secretion of human renin in mesangial cells and other mammalian kidney cells. The current limitation of the evaluated liposomes for an efficient in vivo gene transfer to mesangial cells is the toxicity upon intrarenal arterial administration.

Animals↗
PubMed2001

Flux of amino acids and energy substrates across the leg in weight-stable HIV-infected patients with acute opportunistic infections: indication of a slow protein wasting process.

Increased whole-body proteolysis with muscle protein net degradation has been suggested as one of the causes of weight loss in patients infected with human immunodeficiency virus (HIV). We studied the exchange rates of amino acids and energy substrates across the lower extremity in 16 HIV patients and 16 age-matched controls with similar body cell mass. The patients had either opportunistic infections or chronic diarrhea but no signs of clinical malnutrition. The following findings were obtained in the HIV patients: an augmented peripheral net release of arginine and lysine; an increase in both the negative arterial-venous difference and the efflux of the nitrogen contained in nonmetabolized amino acids; diminished export of 3-methylhistidine; lowered plasma and erythrocyte amino acid concentrations; reduced output of glycerol and furthermore; and neither a net release nor a net uptake of free fatty acids. The findings concerning nitrogen metabolism support the hypothesis that, in the presence of a reduction in protein breakdown, peripheral protein synthesis is severely depressed, making a slow protein wasting process likely to occur. The balances of glycerol and free fatty acids are due not only to the leg tissues but perhaps also in part to increased net retention of these substrates by skeletal muscle.

AIDS-Related Opportunistic Infections↗
PubMed2001

Sodium ferric gluconate complex in the treatment of iron deficiency for patients on dialysis.

Intravenous iron has been found to be an important adjunctive therapy in the treatment of anemia for patients on dialysis. In the United States, iron dextran had been the only form available for parenteral use until 1999. This agent has been associated with a concerning number of severe adverse reactions, in some cases resulting in patients' deaths. Recently, a form of iron used for many years in Europe, sodium ferric gluconate complex in sucrose, was approved for intravenous use in the United STATES: Because this agent does not contain the immunogenic dextran component of iron dextran, it is expected that the safety profile of this drug should be superior to that of iron dextran. The purpose of this review is to critically appraise the relevant literature and to synthesize the information into a strategy for clinical use of this drug.

Anemia, Iron-Deficiency↗
PubMed2001

Veterans aging cohort three-site study (VACS 3): overview and description.

Outcomes for middle-aged and older individuals with HIV infection are poor, and are likely to be mediated by age-related differences in risks and resources (access to care, relationship with the provider, comorbid conditions, health habits, and changes brought about by aging). The goal of the Veterans Aging Cohort Three-Site Study (VACS 3) is to study the influence of age and mediating factors on outcomes with HIV in order to identify mutable mediators of poorer outcomes. VACS 3 is an observational, longitudinal study. Data sources include patient and provider surveys and electronic medical data collected at baseline and 12-month follow-up from the Infections Disease Clinics at three Veterans Affairs Medical Centers (Cleveland, OH, Houston, TX, and Manhattan, NY). Trained Survey Coordinators at each site determined which patients are HIV infected, obtained consent, and asked the patient to complete a questionnaire. The primary provider also completed a questionnaire. Twelve-month follow-up will be completed July 2001. Of all veterans with HIV seen in these clinics 85% (881) have consented and enrolled. Of the 881 corresponding provider surveys, 92% were completed. Mean age is 49; 55% are African-American; 38% of the sample were men who have sex with men; and less than 2% are women. Almost a third (32%) have been without a permanent address. Complimentary or alternative therapies are common as are the use of cigarettes, alcohol, and illicit drugs. The majority (87%) of the patients are taking multiple antiretroviral medications. The median CD4 count is 331 mm(3), and the median viral load was 714 copies/ml. There is substantial variation by site. Veterans with HIV infection have characteristics that will likely become more prevalent among HIV-infected persons in the United States: they are older, commonly suffer comorbid disease, and are members of minority populations. VACS 3 may help inform the design of future clinical interventions to improve outcomes for people aging with HIV.

Aged↗
PubMed2001

The examination of skin lipid model systems stressed by ultraviolet irradiation in the presence of transition metal ions.

In this study, we investigated the effects of ultraviolet (UV) radiation on lipid peroxidation in the presence of ionised iron as a transition metal. Fatty acids as important intercellular stratum corneum lipids and liposomes were used to model skin lipid systems for our experiments. A UV-A laser and a broad spectrum UV lamp were used to create high-level radiation. UV-related damage was quantified by the thiobarbituric acid assay detecting malondialdehyde. Electrospray mass spectrometry was used to characterise peroxidation products following UV exposure. We have shown that hydro- and endoperoxides are long stable intermediates deriving from lipid peroxidation. The incorporation of unsaturated fatty acids into phospholipid liposomes increased the average liposomal diameter and enhanced sensitivity to UV radiation. By comparing our data from laser induced monochromatic UV-A radiation and broad-spectrum UV irradiation, we have demonstrated that UV-A radiation can also induce lipid peroxidation in lipid model systems.

Cholesterol↗
PubMed2001

DNA polymerases II and V mediate respectively mutagenic (-2 frameshift) and error-free bypass of a single N-2-acetylaminofluorene adduct.

The NarI sequence represents a strong mutation hot spot for -2 frameshift mutations induced by N-2-acetylaminofluorene (AAF), a strong chemical carcinogen. Only when bound to the third (underlined) guanine (5'-GGCGCC-->GGCC) can AAF trigger frameshift mutations, suggesting the involvement of a slipped replication intermediate with a two-nucleotide bulge. While base substitutions induced by UV light or abasic sites require DNA polymerase V (Pol V; umuDC), the AAF-induced -2 frameshift pathway requires DNA polymerase II, the polB gene product. Interestingly, error-free bypass of the G-AAF adduct requires Pol V. The genes encoding both Pol II and Pol V are induced by the SOS regulon, a co-ordinated cellular response to environmental stress. A given lesion, G-AAF, can thus be bypassed by two SOS-controlled DNA polymerases (II and V), generating mutagenic (-2 frameshifts) and error-free replication products respectively. Therefore both Pol II and Pol V can compete for the blocked replication intermediate in the vicinity of the lesion and engage in replication by transiently replacing the replicative DNA Pol III. Our data suggest that, in order to cope with the large diversity of existing DNA lesions, cells use a single or a combination of translesional DNA polymerases to achieve translesion synthesis.

2-Acetylaminofluorene↗
PubMed2001

Blood pressure in diabetic nephropathy--current controversies.

Hypertension has been recognized as an early and constant feature of diabetic nephropathy, but recent studies also suggest that a genetic predisposition to hypertension is an important risk factor for diabetic nephropathy. Antihypertensive treatment attenuates progression in diabetic nephropathy, but there is increasing evidence that very early treatment and very low target blood pressures should be implemented. There is also evidence for local activation of the renin system in the kidney as a result of hyperglycaemia. Apart from blood pressure, proteinuria should be monitored and dosing of ACE inhibitors should be guided, also by reduction of protein excretion.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Isotretinoin alleviates renal damage in rat chronic glomerulonephritis.

BACKGROUND: Retinoids, derivatives of vitamin A, have strong anti-inflammatory and antiproliferative properties. We previously demonstrated that the pan-agonists all-transretinoic acid (RA) and isotretinoin (13-cis RA) alleviate renal damage in rat acute glomerulonephritis (GN) induced by anti-Thy-1.1 mAb OX-7. METHODS: The present study examined the effects of low dose and high dose treatment with isotretinoin in the chronic glomerulonephritis model, Thy-GN. Thy-GN was induced by a single intravenous injection of monoclonal antibody (mAb) 1-22-3 in uninephrectomized Wistar rats (N = 7 to 10 per group). Control and nephritic groups were treated with vehicle (veh), low dose isotretinoin (2 mg/kg body wt), or high dose isotretinoin (10 mg/kg body wt). The experiment was terminated 60 days after induction of Thy-GN. RESULTS: In animals with Thy-GN, isotretinoin abrogated the increase in blood pressure and significantly reduced albuminuria. Glomerulosclerosis index, glomerular and interstitial cell counts, as well as the area of the interstitial space were significantly lower in nephritic rats treated with low and high dose isotretinoin compared to vehicle-treated nephritic controls. Treatment with isotretinoin also significantly reduced the number of glomerular and interstitial macrophages. The increase of transforming growth factor (TGF)-beta1, TGF receptor II and prepro-endothelin-1 gene expression in vehicle-treated nephritic rats was significantly attenuated by isotretinoin. CONCLUSIONS: Treatment with isotretinoin significantly reduces glomerular and interstitial damage in rats with chronic glomerulonephritis as indicated by different functional and histological markers. Retinoids may provide a novel therapeutic option for the treatment of glomerulonephritis.

Albuminuria↗
PubMed2001

Low incidence of Epstein-Barr virus-associated posttransplantation lymphoproliferative disorders in 272 unrelated-donor umbilical cord blood transplant recipients.

Umbilical cord blood (UCB) is being increasingly used for transplantation, but the ability of neonatal T cells to regulate Epstein-Barr virus (EBV)-associated lymphoproliferation is unknown. Because UCB transplantation (UCBT) is associated with a relatively low infused dose of donor T cells, frequent donor-recipient HLA disparity, and use of antithymocyte globulin during conditioning, we hypothesized that the risk of EBV-associated posttransplantation lymphoproliferative disorders (EVB-PTLD) after UCBT may be increased. To investigate the incidence of EBV-PTLD after UCBT, we analyzed 272 unrelated-donor UCBTs performed from August 1993 to December 1999 at Duke University Medical Center and the University of Minnesota. Five cases of EBV-PTLD were identified, with a cumulative incidence of 2% (95% confidence interval, 0.3%-3.7%) at 2 years. EBV-PTLD affected UCB recipients aged 1 to 49 years (median, 8 years), with 4 patients undergoing transplantation for leukemia and 1 for immunodeficiency. Patients received UCB grafts that were HLA matched (n = 1) or mismatched at 1 (n = 1) or 2 (n = 3) HLA loci. Diagnoses occurred at 4 to 14 months (median, 6 months) after UCBT, with 4 of 5 patients having preceding grade II to IV acute graft-versus-host disease and 1 being diagnosed at autopsy. Treatment of 4 patients consisted of withdrawal of immunosuppressive treatment and administration of rituximab, with 2 of 4 patients responding. Thus, the incidence of EBV-PTLD after unrelated-donor UCBT appears similar to that observed after transplantation using unrelated bone marrow (BM) and compares favorably with unrelated-donor T-cell-depleted BM transplantation. Because adoptive immunotherapy with donor lymphocytes is not an available option for recipients of unrelated-donor UCBT, new therapeutic strategies are needed, and rituximab appears promising.

Adolescent↗
PubMed2001

Nonmyeloablative conditioning allows for more rapid T-cell repertoire reconstitution following allogeneic matched unrelated bone marrow transplantation compared to myeloablative approaches.

Nonmyeloablative pretransplantation conditioning regimens have resulted in durable engraftment of allogeneic hematopoietic stem cells. In contrast to conventional fully myeloablative approaches, nonmyeloablative regimens are associated with a marked reduction of morbidity and mortality in the early posttransplantation period. Consequently, such reduced-intensity transplantation approaches can be used in older and frailer patients who would not tolerate fully ablative regimens. However, it is currently unclear how this radically different transplantation strategy affects immunological reconstitution. To address this important issue, we used T-cell receptor Vbeta spectratype analysis to examine the distribution of complementarity-determining region 3 (CDR3)-size bands as a measure of the complexity of the redeveloping T-cell repertoire. For this study, we evaluated the T-cell repertoire of 9 patients receiving T-cell replete, matched unrelated donor transplants following fully ablative or nonmyeloablative conditioning regimens. All 4 of the myeloablative and 2 of the nonmyeloablative patients received bone marrow, whereas 3 other nonmyeloablative patients received peripheral blood stem cells. The results of the spectratype analysis demonstrated that the patients who received nonmyeloablative conditioning together with either bone marrow or peripheral blood stem cells exhibited more rapid reconstitution of T-cell repertoire complexity.

Adult↗
PubMed2001

A model of hydraulic interactions in liver parenchyma as forces behind the intrahepatic bile flow.

The small diameters of bile canaliculi and interlobular bile ducts make it hard to attribute the bile flow solely to the process of secretion. In the model liver within its capsule is considered a limited space in which volume expansions of one part are possible only through the shrinking of other parts. The liver capsule allows only very slow volume changes. The rate of blood flow through the sinusoides is governed by the Poisseuill-Hagen law. The model is based on a concept of circulatory liver units. A unit would contain a group of acini sharing the same conditions of arterial flow. We can imagine them as an acinar group behind the last pressure reducer on one arterial branch. Acini from neighboring units compose liver lobules and drain through the same central venule. One lobule can contain acini from several neighboring circulatory units. The perfusion cycle in one unit begins with a transient tide in the arterial flow, governed by local mediators. Corresponding acini expand, grabbing the space by compressing their neighbors in the same lobules. Vascular resistance is reduced in dilated and increased in compressed acini. Portal blood flows through the dilated acini, bypassing the compressed neighbors. The cycle ends when the portal tide slowly diminishes and acinar volume is back on the interphase value until the new perfusion cycle is started in another circulatory unit. Each cycle probably takes minutes to complete. Increased pressures both in dilated and in compressed acini force the bile to move from acinar canalicules. Both up and down changes in acinar volume might force the acinar biliary flow. In cases of arterial vasoconstriction, increased activity of vasoactive substances would keep most of the circulatory units in the interphase and increased liver resistance can be expected. Liver fibrosis makes all acini to be of fixed volume and result in increased resistance. Because of that, low pressure portal flow would be more compromised, as reported. In livers without arterial blood flow, although some slow changes in the portal flows can be expected, acinar volume changes should be reduced. In acute liver injury, enlarged hepatocytes would diminish sinusoidal diameter and increase acinar resistance. In liver tumors, areas of neovascularization with reduced resistance would divert the arterial flow from the normal tissue, while in the compressed perifocal areas, increased vascular resistance should diminish mainly the portal flow.

Bile↗
PubMed2001

Dynamic fatigue properties of the dental implant-abutment interface: joint opening in wide-diameter versus standard-diameter hex-type implants.

STATEMENT OF PROBLEM: The clinical long-term success of single-tooth implant restorations depends, in part, on a stable connection between the prosthetic restoration and the implant body. PURPOSE: The purpose of this experiment was to investigate the fatigue life of UCLA-style abutment screws in wide-diameter versus conventionally sized dental implant restorations. MATERIAL AND METHODS: Five 3.75 x 15-mm and five 6.0 x 15-mm hexed dental implants were used. Ten frameworks were fabricated, 5 with a single UCLA-style, 3.75-mm hexed gold alloy cylinder, and 5 with a single UCLA-style, 6.0-mm hexed gold alloy cylinder. To simulate a common laboratory procedure, 2 abutment interfaces were relieved with a one-quarter round bur for both diameters. The 3.75-mm implant used a Gold-Tite central abutment screw torqued to 32 Ncm, and the 6.0-mm implant used a titanium central abutment screw torqued to 25 Ncm. Frameworks were dynamically loaded ( approximately 10 Hz) with a 120 +/- 10-N, 4-mm off-axis force. Liquid metal strain gauges were used to measure joint opening. Measurements were made at intervals of 10(3), 10(4), 10(5), and 5x10(5) cycles. Gauge output data were converted to displacement with a conversion factor determined by calibration. Linear regression analysis then was performed. RESULTS: Two observations were made in this study. Two of three 3.75-mm nonadjusted specimens and all three 6.0-mm nonadjusted specimens maintained joint closure (range of opening 0-20 microm) while measured under dynamic loading. The median joint opening at 5x10(5) cycles for 3.75-mm nonadjusted specimens was 14 +/- 7 microm; for 6.0-mm specimens, it was 11 +/- 10 microm. Both 3.75-mm adjusted specimens and 1 nonadjusted specimen failed to maintain joint closure (excess joint opening >50 microm). One of the 3.75-mm adjusted specimens had abutment screw fracture. One of two 6.0-mm adjusted specimens failed to maintain joint closure because of screw fracture. CONCLUSION: The dental implant-abutment interface of 3.75-mm and 6.0-mm externally hexed implants experienced similar joint opening after periods of dynamic loading. Laboratory adjustment of the interface significantly decreased the service life of the abutment screw joint.

Analysis of Variance↗
PubMed2001

Early detection of 2-amino-1-methyl-6-phenylimidazo (4,5-b)pyridine(PhIP)-induced mutations within the Apc gene of rat colon.

A large proportion of human cancers result from exposure of individuals to environmental or occupational carcinogens. The early detection of carcinogen-induced mutations is a prerequisite for the identification of individuals at risk for developing cancer. Short G-rich repetitive sequences have been previously identified as hot-spots for frameshift mutagenesis induced by a large variety of carcinogens belonging to several families of widespread environmental pollutants. In order to test if these sequences, when mutated, might serve as biomarkers for carcinogen exposure, we designed a sensitive PCR-based strategy that allows the detection of rare mutational events within a whole genome. 2-Amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), the most abundant carcinogenic heterocyclic amine generated in cooked meat, induces mammary and colon carcinoma in F344 rats. About 25% of male rats exposed to 400 p.p.m. PhIP in the diet for >43 weeks present colon tumors with specific -1G mutations within 5'-GGGA-3' sequences of the APC: gene. Using our PCR assay we have assessed the occurrence of such specific events in rats exposed to PhIP for only 1, 2, 4 and 6 weeks. A specific amplification signal was already observed in the 1 week-treated population and increases in a treatment time-dependent manner. These data validate this approach for the early detection of mutations and demonstrate its usefulness for molecular epidemiology and early diagnosis.

Animals↗