Biomedical subjects

N Wernert

Publications and source records attributed to N Wernert.

At least 37 records · Page 2Linked to original sources

PubMed1999

Loss of heterozygosity, differentiation, and clonality in microdissected male germ cell tumours.

Testicular germ cell tumours (TGCTs) are heterogeneous neoplasms with different histological patterns and malignant potential. The aim of this study was to determine whether the main TGCT subtypes (seminoma, embryonal carcinoma, yolk sac tumour, choriocarcinoma, and mature teratoma) are distinguished by their loss of heterozygosity (LOH) patterns and whether LOH typing can help to distinguish between clonal and multifocal development of different components in mixed TGCTs. In 76 tumours analysed for allelic losses at 25 chromosomal loci, different LOH patterns were found in distinct histological subtypes. A region around D18S543 frequently lost in yolk sac tumours could harbour one or more tumour suppressor genes. In 20 microdissected mixed tumours, losses of identical alleles in different histological components in 11 of 20 cases (over 50 per cent) were found, which is in favour of current histogenetic models of clonal TGCT development. Clonal losses were most often found at D13S317 (6 of 20 tumours). Two classes of allelic losses may therefore occur during TGCT development: clonal losses which are involved in early transformational events and others related to TGCT differentiation along different lines.

Adult↗

PubMed1999

Loss of heterozygosity (LOH), malignancy grade and clonality in microdissected prostate cancer.

The aim of the present study was to find out whether increasing malignancy of prostate carcinoma correlates with an overall increase of loss of heterozygosity (LOH), and whether LOH typing of microdissected tumour areas can help to distinguish between multifocal or clonal tumour development. In 47 carcinomas analysed at 25 chromosomal loci, the overall LOH rate was found to be significantly lower in grade 1 areas (2.2%) compared with grade 2 (9.4%) and grade 3 areas (8.3%, P = 0.007). A similar tendency was found for the mean fractional allele loss (FAL, 0.043 for grade 1, 0.2 for grade 2 and 0.23 for grade 3, P = 0.0004). Of 20 tumours (65%) with LOH in several microdissected areas, 13 had identical losses at 1-4 loci within two or three areas, suggesting clonal development of these areas. Markers near RB, DCC, BBC1, TP53 and at D13S325 (13q21-22) showed higher loss rates in grades 2 and 3 (between 25% and 44.4%) compared with grade 1 (0-6.6%). Tumour-suppressor genes (TSGs) near these loci might, thus, be important for tumour progression. TP53 mutations were detected in 27%, but BBC1 mutations in only 7%, of samples with LOH. Evaluation of all 25 loci in every tumour made evident that each prostate cancer has its own pattern of allelic losses.

Alleles↗

PubMed1999

[Inhibition of angiogenesis on the chicken chorioallantoic membrane by Ets 1 antisense oligodeoxyribonucleotides].

The Ets 1 transcription factor, the founder of the ets gene family of transcriptional regulators, has strongly been supposed to play a role in angiogenesis under both physiological and pathological conditions including tumor vascularization. An in vivo role has nevertheless not yet been proven. We therefore investigated whether an Ets 1 antisense oligodesoxynucleotide (ODN) blockade effectively inhibits in vivo angiogenesis in the chicken chorioallantois membrane-assay. We used a 20-mer phosphorothioate directed against the AUG initiation codon and a short 3' sequence of the c-ets 1 mRNA (5'-AGATCGACGGCCGCCTTCAT-3') in order to block Ets 1 expression. Three quantities of either antisense or negative control sense ODNs were directly applied on the chorioallantois membrane on day five of development and results evaluated on day seven. No effect on angiogenesis was seen in the antisense group treated with 2.5 micrograms ODN/egg compared to the sense control group. In contrast chorioallantoic blood vessel numbers and diameters were considerably reduced after application of 5 micrograms antisense ODN. 10 micrograms of either antisense or sense ODNs turned out to be toxic: all 6 embryos had died on day seven. Our results are the first proof that the Ets 1 transcription factor is actually necessary for the regulation of in vivo angiogenesis. Its role is probably not restricted to development but also concerns new blood vessel formation during chronic inflammation and tumor vascularization.

Allantois↗

PubMed1998

[Genetic alterations in the fibroblastic stroma of invasive colon and breast carcinomas].

While the neoplastic cells have always been in the center of interest in cancer research in recent years, more and more attention has been paid also to the tumor stroma which is today known to play an important role for tumor progression. In early days of histology the interpretation of stroma as either neoplastic or reactive was still a matter of discussion. Today's generally held view is clearly in favor of a secondary induction by tumor cell derived factors. Recent findings of epithelium-mesenchymal transitions of cultured tumor cells now put again a doubt on this exclusive interpretation. In the present work we show for the first time that genetic alterations (allelic losses, microsatellite instabilities and p53 mutations) are not restricted to tumor cells but also occur within the fibroblastic stroma of non-hereditary invasive human colon and breast cancers. In view of the clonality of epithelial and stromal components in the same cases (loss of same alleles and identical MSI patterns) epithelium-mesenchymal transitions are among possible explanations for these findings which could shed a new light on the true nature of tumor stroma.

Amino Acid Substitution↗

PubMed1997

Morphological analogies of fetal prostate stroma and stromal nodules in BPH.

BACKGROUND: A "reawakening" of ontogenetic processes in the development of BPH is still in debate. Therefore, morphological analogies of fetal prostate stroma and nodular stromal proliferates in BPH were investigated. METHODS: Fetal prostates (n = 30; weeks 12-40 of gestation) and stromal nodules of benign prostatic hyperplasia (n = 375 from autopsies, n = 100 from biopsies) were investigated by histo- and immunohistochemistry with special regard to cytoskeletal (alpha-actin, desmin, myosin, and vimentin), neuronal (S-100 protein), neuroendocrine (neuron-specific enolase), leukocytic (CD3, CD20, and CD68) and vascular (CD34, BMA-120, and factor VIII) antigens. RESULTS: The developing fetal prostate stroma consists of immature mesenchymal cells up to week 17 of gestation, followed by fibroblastic and fibromuscular stromal cells up to week 25 of gestation and predominantly smooth-muscular cells until the end of gestation. Stromal nodules occur as immature mesenchymal, fibroblastic, fibromuscular, and smooth-muscular, suggestive of a maturational process. The fetal prostate stroma and the stromal nodules present, with an increasing degree of maturation, a similar vascular pattern and a similar occurrence of CD3 (T-lymphocytes), CD20 (B-lymphocytes), CD68 (macrophages), S-100, and neuron-specific enolase-positive cells. CONCLUSIONS: The data suggest that ontogenetic processes are recapitulated in the development of stromal nodules in benign prostatic hyperplasia, supporting the idea of a "re-awakening" of fetal processes in BPH.

Adult↗

PubMed1997

MIB-1 immunohistochemistry in clinical stage I nonseminomatous testicular germ cell tumors predicts patients at low risk for metastasis.

BACKGROUND: The clinical Stage I of nonseminomatous germ cell tumors (NSGCT) is inaccurate in 30% of patients. In previous studies on tumor biologic risk factors, low tumor proliferation rates predicted a group of patients at low risk for occult metastatic disease. The goal of this study was to confirm the immunohistochemical assessment of tumor proliferation using MIB-1 (Ki-67 receptor) in a different patient cohort with different investigators to prove the method's reliability. METHODS: Orchiectomy specimens of 78 patients with clinical Stage I NSGCT (50 patients with pathologic Stage I and 28 patients with pathologic Stage II disease, all patients underwent retroperitoneal lymph node dissection) were retrospectively analyzed by histopathologic reevaluation and MIB-1 immunostaining. RESULTS: Mean MIB-1 values between the two pathologic stages differed significantly (51.5% MIB-1 positive tumors cells in pathologic Stage I and 75.1% MIB-1 positive tumor cells in pathologic Stage II disease; P = 0.02). Using a 70% cutoff value, pathologic stages were correctly classified in 69% of cases (sensitivity of 86%, specificity of 60%, negative predictive value of 88%, and positive predictive value of 55%). Compared with traditional risk factors such as percentage of embryonal carcinoma and vascular invasion, in multivariate analysis, MIB-1 was the best predictor of patients at low risk for metastasis. CONCLUSIONS: This study in a different patient population with different investigators confirmed previous results of MIB-1 staining to predict a group of patients with clinical Stage I NSGCT who were at low risk for metastasis. The method is simple and reproducible to improve risk classification in low stage testicular carcinoma. Using this technique, a group of patients at very low risk for metastasis can be identified. [See editorial counterpoint on pages 1641-5 and reply to counterpoint on page 1646, this issue.]

Antibodies, Monoclonal↗

PubMed1997

The multiple roles of tumour stroma.

Since the work of Judah Folkman in the 1970s demonstrating the importance of vascularization on tumour growth the many roles played by tumour stroma have been demonstrated. Vascular endothelial growth factor/vascular permeability factor appears to be the main in vivo inducer of both stromal blood vessels and other components of the tumour stroma. Its action is probably mediated through its strong and long-lasting effect on microvascular permeability leading to fibrin extravasation and organisation ("tumours are wounds that do not heal"). During tumour invasion, stromal fibroblasts participate in the degradation of the extracellular matrix (ECM) by secreting matrix degrading proteases as well as their downstream-activators. Stroma derived factors such as scatter factor/hepatocyte growth factor as well as interactions between neoplastic cells and the ECM can play a role in both tumour cell migration and proliferation. The ECM may also act as a reservoir for growth factors. A novel transcription factor encoded by the c-ets 1 proto-oncogene is likely to be involved in the transcriptional regulation of both tumour vascularization and invasion. This contribution summarizes recent developments in the tumour stroma field.

Animals↗

PubMed1996

Stromal nodules in benign prostatic hyperplasia.

OBJECTIVE: Stromal nodules from benign prostatic hyperplasia (BPH; n = 375 from autopsy, n = 100 from biopsy specimens) were investigated with regard to cytoskeletal components, topography, vascularization, leukocytic infiltrates, and proliferative activity. METHODS: The nature of stromal nodules was studied by histopathology and immunohistochemistry, using antibodies against alpha-actin, desmin, myosin, vimentin, BMA-120, factor VIII, CD3, CD4, CD20, CD34, CD45RO, CD68, PCNA, and MiB1. RESULTS: The findings lead to an extended classification of stromal nodules in BPH: immature mesenchymal (IM; 8.8%), fibroblastic (FB; 65.2), fibromuscular (FM; 21.6), and smooth muscular (SM; 4.4%). The different types occurred in all age decades in a similar distribution (FB > FM > IM > SM). Topographical studies (modified zonal subdivision of McNeal) revealed stromal nodules predominantly in the transitional zone (n = 286), less in the central zone (n = 78), occasionally in the peripheral zone (n = 11), and predominantly in the periurethral (n = 287) and less in the intermediate (n = 84) and subcapsular (n = 4) regions. The different types of nodules presented a distinct vascular pattern. FB, FM, and SM nodules showed significantly increased diffuse infiltrates of T lymphocytes-mainly T helper cells (mean 73%)-and an increase of B lymphocytes. Proliferative activity in the nodules was not observed. Stromal nodules were not observed in normal nonhyperplastic prostates; they only occurred in combination with hyperplastic nodular glandular proliferates. CONCLUSIONS: The findings are suggestive of a maturational sequence of stromal nodules in BPH and of a possible significance of immunocompetent cells in the development of stromal nodules and further suggest that both stroma and epithelium of the prostate respond with nodular hyperplasia to the stimulus, which causes BPH.

Adult↗

PubMed1995

Invasive tumors induce c-ets1 transcription factor expression in adjacent stroma.

The stroma reaction plays a central role in tumor growth, invasion and metastasis. Tumor growth is dependent on angiogenesis and requires the vascular supply provided by new capillary blood vessels of the stroma. The expression of the gene encoding the transcription factor c-ets1 is localized within fibroblasts and endothelial cells of the stromal compartment. This expression correlates with the accumulation of transcripts for potential target genes such as collagenase I and stromelysin I in stromal fibroblasts surrounding malignant cells in invasive tumors. We suggest that c-Ets1 protein might regulate the transcription of the genes coding for matrix-degrading proteases necessary for both angiogenesis and tumor invasion.

Angiogenesis Inducing Agents↗

PubMed1995

The H19 gene is expressed within both epithelial and stromal components of human invasive adenocarcinomas.

In a previous work, we have isolated the human H19 gene and shown accumulation of transcripts in various human tumors including breast carcinomas (Douc-Rasy et al (1993) Int J Oncol 2, 753-758). Questions arose, after Northern blot results, about the precise H19 mRNA location, specially in normal breast tissues and benign or malign primary breast tumors. Then we performed molecular in situ hybridization to get insight into tissue expression of the H19 gene. Examined resections included one normal tissue, one fibroadenoma and 13 cancers. Results obtained with the H19 probe can be summarized as follows: 1) in normal breast tissues signals were focally observed in epithelial cells, but more predominantly in the palleal tissue which is sensitive to hormones; 2) in the fibroadenoma, fibroblastic cells were extensively labeled at the stroma-epithelium boundary, but epithelial cells were negative; and 3) in primary cancers, eight specimens exhibited signals on stromal cells, one specimen on epithelial cells and four on both epithelial and stromal cells. Data provide the following evidence: 1) usually labeled cells are clustered, either within normal or pathological tissues; 2) the labeling pattern highly differs from one tumor to another; and 3) H19 probe displays very different signals from one cell to another in given compartment of a given tissue section. In conclusion, it seems that a high H19 expression matches the tumor invasion. Our results suggest that the expression of this gene is concerned by the relationships between epithelial and stromal cells, and can reflect peculiar physiological states of the cells. Furthermore, we discuss results showing an abundant expression of H19 gene in some adenocarcinomas of bad prognosis, in the context of the otherwise established tumor-suppressor role of this gene, or the strictly controlled gene dosage, which could be overridden in these particular cases.

Adenocarcinoma↗

PubMed1995

Restenosis after coronary angioplasty.

The major disadvantage of using percutaneous transluminal coronary angioplasty to treat patients with atherosclerotic coronary disease is the frequent occurrence of restenosis after an initially successful procedure. Studies in animals and histological observations in man have demonstrated that restenosis is characterized by neointimal hyperplasia due to smooth muscle cell proliferation and to the synthesis of extracellular matrix. Improvements in technology or pharmacological interventions have had no significant impact on the rate of restenosis. In spite of our increased understanding of the molecular mechanisms of restenosis. no effective treatment is available at the present time. Gene therapy, which has produced encouraging initial results in experimental models, may provide a solution in the medium term.

Angioplasty, Balloon, Coronary↗

PubMed1995

Expression of c-ets-1, collagenase 1, and urokinase-type plasminogen activator genes in lung carcinomas.

The c-ets-1 transcription factor has been involved in the in vitro transactivation of matrix-degrading protease genes that might play an important role in tumor invasion. Using in situ hybridization, we analyzed serial frozen sections for c-ets-1, collagenase 1, and urokinase-type plasminogen activator gene expression in 54 lung carcinomas including 34 non-neuroendocrine carcinomas (18 squamous carcinomas, 10 adenocarcinomas, 3 large cell carcinomas, and 3 basaloids) and 20 neuroendocrine carcinomas (7 small cell lung carcinomas, 4 large cell neuroendocrine carcinomas, 4 well differentiated neuroendocrine carcinomas, and 5 carcinoids). c-ets-1 gene was expressed in stromal cells in 44/54 lung carcinomas including one metastasizing carcinoid. c-ets-1 transcripts were also detected in cancer cells more frequently in neuroendocrine than in non-neuroendocrine carcinomas (P = 0.0059) and in stages III and IV and metastasis more frequently than in stages I and II ( P = 0.0065). Collagenase 1 gene was expressed in 16/34 non-neuroendocrine tumors and in 1/20 neuroendocrine tumors, either in stromal (12/17) or in cancer cells (6/17). Urokinase-type plasminogen activator mRNAs were expressed in 45/54 lung carcinomas in stromal and/or cancer cells. In non-neuroendocrine tumors, c-ets-1 and collagenase 1 gene expressions in stromal cells were correlated. These results demonstrate that the transcription factor c-ets-1, collagenase 1, and urokinase-type plasminogen activator are involved in lung cancer invasion and suggest that c-ets-1 protein might transactivate collagenase 1 gene during tumor invasion.

Carcinoma↗

PubMed1995

Angiotensin converting enzyme inhibition prevents proto-oncogene expression in the vascular wall after injury.

OBJECTIVES: Angiotensin converting enzyme (ACE) inhibitors reduce neointimal hyperplasia after balloon denudation, but the mechanisms are not completely understood. It has been demonstrated that nuclear oncogenes are induced in the vascular wall in the hours immediately after injury, and that the same genes are induced by angiotensin II in vascular smooth muscle cells. It has therefore been suggested that the effects of ACE inhibitors on the response of the vessel wall could be mediated by an inhibition of proto-oncogene expression. METHODS AND RESULTS: Sixteen New Zealand White rabbits were randomly assigned for histologic analysis to receive placebo (n = 9) or 1 mg/kg per day perindopril (n = 7). After treatment for 7 days balloon aortic injury was performed. The treatment was continued and the rabbits were killed 28 days after injury. In the perindopril group the neointimal cross-sectional area was significantly smaller than in the control group. Six untreated rabbits were used to assess the time course of proto-oncogene expression in the aortic wall after injury in the present model. After extraction, total aortic RNA was hybridized with myc, fos and jun probes. Based on the results, the effects of ACE inhibition on proto-oncogene expression were tested 1 h after balloon denudation. Accordingly, 24 rabbits were randomly assigned to pretreatment for 7 days with placebo or with 1 or 10 mg/kg per day perindopril (n = 8, for each group) and were killed 1 h after injury. Expression of c-myc was not altered by pretreatment. However, 1 mg/kg per day perindopril induced significant reductions of 50% in c-jun and 45% in c-fos expression compared with control. No additional effect was obtained with the higher dose. CONCLUSION: The effect of ACE inhibition on intimal hyperplasia is associated with a reduction in early cellular events such as c-fos and c-jun expression. These results suggest that potent ACE inhibition at the time of vascular injury may be required to limit the hyperplastic response of the vessel wall.

Animals↗

PubMed1995

Neointimal thickening after balloon denudation is enhanced by aldosterone and inhibited by spironolactone, and aldosterone antagonist.

OBJECTIVE: The aim was to examine the effects of aldosterone and of an aldosterone antagonist, spironolactone, on neointimal thickening in a rabbit model of balloon injury. METHODS: Eighteen rabbits underwent aortic and iliac balloon injury and were randomised to subcutaneous infusion of aldosterone (70 micrograms.kg-1.d-1) or vehicle solution for 28 d. Eighteen other rabbits were randomised to receive daily subcutaneous injections of spironolactone (50 mg.kg-1.d-1) or of vehicle for 7 d before injury and for 28 d after the procedure. All animals were then killed just after measurement of plasma renin activity and of arterial pressure. Vessels were fixed and five cross sections were analysed per rabbit (three aortic; two from iliac artery). Mean values of neointimal area and of the neointimal area/medial area ratio were calculated. RESULTS: Aldosterone treatment was associated with a decrease in renin activity and a non-significant increase in mean arterial pressure. Aldosterone significantly augmented the neointimal thickening in the iliac artery [0.42(SEM 0.07) v 0.24(0.03) mm2, P < 0.05] but not in the aorta [0.63(0.08) v 0.59(0.12) mm2, NS]. Spironolactone significantly inhibited intimal thickening, both in the iliac artery [0.09(0.02) v 0.29(0.01) mm2, P < 0.001] and in the aorta [0.31(0.03) v 0.59(0.06) mm2, P < 0.001]. Spironolactone administration was associated with an increase in renin activity and a decrease in mean arterial blood pressure. CONCLUSIONS: Aldosterone administration enhances neointimal thickening after injury and spironolactone, an aldosterone antagonist, is a potent inhibitor of neointimal thickening in the same model. This suggests a role for aldosterone in the pathophysiology of neointimal proliferation after balloon injury and for aldosterone antagonists in its prevention.

Aldosterone↗

PubMed1994

Stromal expression of c-Ets1 transcription factor correlates with tumor invasion.

The stroma reaction has an important role in tumor growth, invasion, and metastasis. In various invasive human carcinomas, as well as in a mouse model for tumor invasion, transcripts encoding the transcription factor c-Ets1 were detected within stromal fibroblasts, whereas they were absent in epithelial tumor cells. This expression of c-Ets1 was often increased in fibroblasts directly adjacent to neoplastic cells. Endothelial cells of stromal capillaries were also positive for c-Ets1 expression. In contrast, fibroblasts of corresponding noninvasive lesions and of normal tissues were consistently negative. In cultured human fibroblasts stimulated by basic fibroblast growth factor and tumor necrosis factor alpha, the expression of c-Ets1 correlated with the accumulation of transcripts for potential target genes, collagenase-1 and stromelysin-1. The same correlation was observed in some of the invasive carcinomas investigated. These results suggest that c-Ets1 participates in the regulation of tumor invasion in vivo.

Adult↗

PubMed1994

In vivo cooperation of two nuclear oncogenic proteins, P135gag-myb-ets and p61/63myc, leads to transformation and immortalization of chicken myelomonocytic cells.

To investigate a possible in vivo cooperation between the p61/63myc and P135gag-myb-ets proteins, we used a previously constructed retrovirus, named MHE226, which contains the fused v-myb and v-ets oncogenes of the E26 retrovirus and the v-myc oncogene of MH2. For that purpose, chicken neuroretina cells producing MHE226 and pseudotyped with the Rous associated virus-1 (RAV-1) helper virus were injected in 1-day-old chickens. In control experiments, we also injected chicken neuroretina cells producing E26 (RAV-1), RAV-1 alone, or constructs lacking one of the oncogenes of MHE226. The average life span of MHE226-infected chickens is half that of E26-infected chickens. MHE226-infected chickens harbor tumors scattered in many organs, but compared with E26, MHE226 induced a weak leukemia. Study of integration sites suggests that the majority of the tumors results from clonal or oligoclonal events. Cell cultures were derived from the tumors of MHE226-infected chickens and grown in standard medium without addition of exogenous chicken myelomonocytic growth factor. These cells still divide at high rate after more than 100 passages and can thus be considered immortalized. By using several criteria, these cells were characterized as precursors of the myelomonocytic lineages.

Animals↗

PubMed1994

Angiopeptin inhibits oncogene induction in rabbit aorta after balloon denudation.

BACKGROUND: Angiopeptin, a synthetic cyclic octapeptide analogue of somatostatin, reduces neointimal hyperplasia after balloon denudation of rabbit aorta if administered before injury. The aim of this study was to analyze the effect of angiopeptin pretreatment on the level of expression of the c-fos and c-jun protooncogenes, early markers of smooth muscle cell proliferation, after balloon denudation of rabbit aorta. METHODS AND RESULTS: For histological analysis of the effect of angiopeptin on neointimal thickening after aortic balloon denudation, rabbits were randomized into three groups: group 1 (controls), twice-daily injections of saline begun 24 hours before balloon denudation (n = 9); group 2, twice-daily injections of angiopeptin 10 micrograms/kg begun 24 hours before balloon denudation (n = 9); and group 3, twice-daily injections of angiopeptin 10 micrograms/kg begun 1 hour after balloon denudation (n = 7). The degree of neointimal thickening 28 days after balloon denudation was significantly less in group 2 than in group 1 (neointimal area: group 1, 0.59 +/- 0.11 mm2; group 2, 0.22 +/- 0.05 mm2; P < .05. Neointima/media: group 1, 0.85 +/- 0.17; group 2, 0.23 +/- 0.05; P < .05). When angiopeptin was started 1 hour after denudation (group 3), however, the neointimal area (0.52 +/- 0.09 mm2) and the neointima/media ratio (0.76 +/- 0.10) were not statistically different from the control group. For analysis of protooncogene induction, rabbits received twice-daily subcutaneous injections of saline (n = 7), angiopeptin 10 micrograms/kg (n = 8), or angiopeptin 100 micrograms/kg (n = 4) begun 24 hours before balloon denudation. The animals were killed 30 minutes after balloon denudation, and total aortic RNA was hybridized with fos and jun probes. Expression of c-fos and c-jun was detected 30 minutes after injury; angiopeptin pretreatment at 20 micrograms.kg-1.d-1 induced a 41% reduction in c-fos expression and a 42% reduction in c-jun expression compared with control animals. The inhibitory effect at the higher dose of angiopeptin was similar. CONCLUSIONS: Our results show that the inhibitory effect of angiopeptin on neointimal thickening is related to events that occur very early after injury and suggest that the inhibition of smooth muscle cell activation may be responsible, at least in part, for this effect.

Animals↗

PubMed1994

Long-term oral administration of L-arginine reduces intimal thickening and enhances neoendothelium-dependent acetylcholine-induced relaxation after arterial injury.

BACKGROUND: Nitric oxide (NO), in addition to its potent vasorelaxant properties, may participate in growth regulation of cultured smooth muscle cells. It was recently demonstrated that in vivo endothelial injury induces the production of NO from L-arginine in the arterial wall. METHODS AND RESULTS: We studied the effects of long-term administration of L-arginine, the precursor of NO, on neointimal thickening and on neoendothelium-dependent vasorelaxation 4 weeks after balloon denudation of normocholesterolemic rabbit iliac arteries. Rabbits were fed with either a standard diet or a diet supplemented with L-arginine (2.25%) in their drinking water 3 days before and during 4 weeks after balloon denudation. The effectiveness of L-arginine supplementation was confirmed by measurement of plasma arginine levels. L-Arginine had no effect on hemodynamic parameters. All animals were killed 4 weeks after balloon denudation, and a digital histomorphometric analysis of three serial nonconsecutive histological cross sections per iliac artery was performed. Intimal thickening was reduced (P < .05) from 0.43 +/- 0.08 (SE) mm2 in controls (n = 8) to 0.24 +/- 0.02 mm2 in treated animals (n = 8). Ten animals (n = 5 in each group) were used for in vitro vasoreactivity assessment 4 weeks after balloon denudation. Neoendothelium-dependent acetylcholine-induced relaxation (10(-8) mol/L to 3.10(-5) mol/L) in treated animals (Emax = -24.1 +/- 5.5%) was significantly greater than in controls (Emax = -8.9 +/- 2.2%). Endothelium-independent relaxation did not differ between groups (Emax = -58.1 +/- 6.5% in L-arginine-supplemented animals versus -52.9 +/- 6.8% in controls). CONCLUSIONS: Our results demonstrate that L-arginine, a precursor of NO, reduces neointimal thickening after balloon denudation and improves neoendothelial-dependent acetylcholine-induced relaxation.

Acetylcholine↗