Dipyridamole directly inhibits vascular smooth muscle cell proliferation in vitro and in vivo: implications in the treatment of restenosis after angioplasty.

OBJECTIVES: The effect of dipyridamole on smooth muscle cell proliferation and prevention of intimal thickening after arterial injury was investigated. BACKGROUND: In addition to antiplatelet activity, dipyridamole also inhibits cell proliferation. We examined whether the antiproliferative action of dipyridamole on smooth muscle cells, as demonstrated here, has a direct effect on intimal thickening after vascular injury. METHODS: Cell proliferation was determined by measuring deoxyribonucleic acid (DNA) synthesis and by cell counting. The in vivo effect of locally delivered dipyridamole was determined in a rabbit model with carotid or femoral artery injury. RESULTS: Dipyridamole produced a dose-dependent inhibition of smooth muscle cell proliferation, producing 50% inhibition at 7 micrograms/ml. Structural analogues SH-869 and mopamidol were 10 to 100 times less effective than dipyridamole, suggesting that cell growth inhibition may be unrelated to the antiplatelet activity of dipyridamole. Inhibition of cell proliferation by dipyridamole was attenuated by increasing the serum concentration in the culture medium. Bypassing serum by local delivery of dipyridamole at the periadventitial site produced 63% inhibition (p < 0.05) of cell replication in balloon-injured arteries. Locally delivered dipyridamole also inhibited intimal thickening (20%, p < 0.05) after balloon injury. CONCLUSIONS: Dipyridamole inhibited smooth muscle cell proliferation in vitro. This activity was attenuated by serum proteins. Locally delivered dipyridamole inhibited cell replication in arteries and intimal thickening after balloon injury. These results suggest that although systemic treatment with dipyridamole may not be efficacious because of inadequate serum levels, its antiproliferative action on smooth muscle cells may reduce restenosis when the drug is delivered locally after coronary angioplasty.

Influence of standard treatment on ileal and colonic antimicrobial defensin expression in active Crohn's disease.

BACKGROUND: Crohn's Disease (CD), a chronic intestinal inflammation, is currently treated primarily by therapeutics which are directed against inflammatory responses. Recent findings though suggest a central role of the innate immune barrier in the pathophysiology. Important factors providing this barrier are antimicrobial peptides like the alpha- and beta-defensins. Little is known about in vivo effects of common drugs on their expression. AIM: To analyse the influence of corticosteroids, azathioprine and aminosalicylate treatment on ileal and colonic antimicrobial peptides in active CD and also assess the role of inflammation. METHODS: We measured the expression of antimicrobial peptides and pro-inflammatory cytokines in 75 patients with active CD. RESULTS: Ileal and colonic alpha- and beta-defensins as well as LL37 remained unaffected by corticosteroids, azathioprine or aminosalicylate treatment. Additionally, we did not observe a negative coherency between Paneth cell alpha-defensins and any measured cytokines. HBD2 and LL37 unlike HBD1 levels were linked to inflammatory cytokines and increased in highly inflamed samples. CONCLUSIONS: Current oral drug treatment seems to have no major effect on the expression of antimicrobial peptides. In contrast to HBD2 and LL37, ileal levels of HD5 and HD6 and colonic HBD1 level are independent of current inflammation. Innovative drugs should aim to strengthen protective innate immunity.

Efficacy of double-balloon enteroscopy in the evaluation and treatment of bleeding and non-bleeding small bowel disease.

Double-balloon enteroscopy (DBE) is a newly developed method allowing deep insertion of a thin endoscope into the small bowel, thereby enabling inspection, biopsy and endoscopic treatment of previously inaccessible lesions. This retrospective analysis evaluates the diagnostic and therapeutic efficacy in all patients undergoing DBE at our institution. A total of 109 DBEs were performed in 82 patients (57 patients with suspected small bowel blood loss and 25 patients with other indications). The diagnostic success rate was 51 of 82 (62 %) with a higher rate in bleeders in whom angiodysplasias were the most frequent diagnosis. DBE had therapeutic consequences in 47 patients (57 %), of whom 33 patients (40 %) underwent endoscopic therapy and 6 patients (7 %) surgery. In 4 patients, malignant neoplasias were newly diagnosed (2 gastrointestinal stroma tumors, 1 neuroendocrine tumor, 1 adenocarcinoma). Other diagnostic modalities were helpful in preselecting patients for DBE and choosing the more favorable (oral or anal) access. In 16 of 26 patients, pathological findings in videocapsule endoscopy were substantiated by DBE. In 7 patients, the findings of CT or MRI enteroclysis, and in 4 patients with hematochezia, the results of a preceding erythrocyte bleeding scan were confirmed by DBE. In conclusion, this series indicates that DBE of the small bowel - in concert with other diagnostic modalities - has a high diagnostic and therapeutic efficacy.

Urinary excretion of polyethylene glycol 3350 during colonoscopy preparation.

BACKGROUND: Whole gut lavage with a polyethylene glycol electrolyte solution (PEG) is a common bowel cleansing method for diagnostic and therapeutic colon interventions. Absorption of orally administered PEG from the gastrointestinal tract in healthy human beings is generally considered to be poor. In patients with inflammatory bowel disease (IBD), intestinal permeability and PEG absorption were previously reported to be higher than in normal subjects. In the current study, we investigated the absorption of PEG 3350 in patients undergoing routine gut lavage. METHODS AND RESULTS: Urine specimens were collected for 8 hours in 24 patients undergoing bowel cleansing with PEG 3350 for colonoscopy. The urinary excretion of PEG 3350, measured by size exclusion chromatography, ranged between 0.01 and 0.51 % of the ingested amount, corresponding to 5.8 and 896 mg in absolute amounts, respectively. Mean PEG excretion in patients with impaired mucosa such as inflammation or ulceration of the intestine (0.24 % +/- 0.19, n = 11) was not significantly higher (p = 0.173) compared to that in subjects with macroscopically normal intestinal mucosa (0.13 % +/- 0.13, n = 13). CONCLUSION: The results indicate that intestinal absorption of PEG 3350 is higher than previously assumed and underlies a strong inter-individual variation. Inflammatory changes of the intestine do not necessarily lead to a significantly higher permeability of PEG.

Interstitial pneumonitis during combination therapy with interferon-alpha and ribavirin in a patient with chronic Hepatitis C.

After nine weeks of combination therapy with recombinant interferon-alpha and ribavirin for chronic hepatitis C a 62-year old woman complained of a dry cough and exertional dyspnea. An elevated erythrocyte sedimentation rate was noticed. Prior to treatment chest X-rays and physical examination revealed no pulmonary abnormalities. Inhalative steroids did not improve the symptoms and afer 12 weeks treatment chest X-ray and computed tomography showed bilateral reticonodular lung infiltration suggesting a diagnosis of interstitial pneumonitis. Cough and dyspnea resolved and abnormal lung shadows were reversible within two months following discontinuation of interferon-/ribavirin treatment. In the Japanese literature there are similar reports on pneumonitis occurring during high-dose IFN-alpha and concomitantly Chinese herbal medicine treatment. To our knowledge this is one of the first cases of interstitial pneumonitis due to combination therapy with IFN-alpha and ribavirin in chronic hepatitis C reported in the western world.

Mechanism of tetracycline-hydrochloride-induced pleurodesis. Tetracycline-hydrochloride-stimulated mesothelial cells produce a growth-factor-like activity for fibroblasts.

Intrapleural instillation of tetracycline hydrochloride (TCN) is an effective means of achieving pleural fibrosis. However, its mechanism of action remains unknown. To evaluate the hypothesis that TCN stimulates pleural mesothelial cells to release growth-factor-like activity for fibroblasts we performed the following experiments. Rat visceral pleural mesothelial cells were incubated with TCN at doses ranging from 0.01 microgram/ml to 100 mg/ml. The conditioned media (CM) were collected after incubation for 2 to 48 h. CM caused fibroblasts to increase incorporation of thymidine when compared with CM that was unexposed to TCN (p less than 0.05). This growth-factor-like activity continued to be produced by mesothelial cells for 48 h after removal of TCN from the medium. There was a dose-response relationship since increasing doses of TCN to as much as 1 mg/ml caused increasing production of growth-factor-like activity without mesothelial cell injury as measured by trypan blue exclusion. The growth factor activity was a competence-type activity. It coeluted with human PDGF at a molecular weight of 31,000. It was heat-stable (100 degrees C for 10 min) and sensitive to trypsin and papain but not to heat-inactivated trypsin. Addition of cycloheximide or actinomycin D inhibited its production. TCN did not have any direct effect on fibroblasts. Bleomycin CM did not contain growth-factor-like activity for fibroblasts. These data demonstrate that TCN stimulates mesothelial cells to release a growth-factor-like activity for fibroblasts. This phenomenon may play an important role in TCN-induced pleural fibrosis.

Investigation of neutrophil signal transduction using a specific inhibitor of phosphatidylinositol 3-kinase.

Neutrophils contain a multicomponent NADPH oxidase system that is involved in the production of microbicidal oxidants. Stimulation of human neutrophils with the peptide FMLP activates this respiratory burst enzyme to produce superoxide and also has been shown to result in activation of phosphatidylinositol (Ptdlns) 3-kinase. Treatment of human neutrophils with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), a potent and specific inhibitor of Ptdlns 3-kinase, resulted in complete inhibition of Ptdlns 3-kinase activity as well as in inhibition of superoxide production in FMLP-treated neutrophils in suspension; FMLP-stimulated oxidant production in adherent cells was also abolished. Treatment of human neutrophils with PMA resulted in production of superoxide without activation of Ptdlns 3-kinase; LY294002 did not block superoxide production in neutrophils exposed to PMA. In addition, LY294002 did not inhibit cellfree NADPH oxidase activation, CD11b-dependent adhesion, actin polymerization in response to FMLP, or FMLP-induced calcium flux. These results suggest that the signal transduction pathway of the FMLP-receptor involves activation of Ptdlns 3-kinase, which is required for subsequent superoxide production induced by the chemotactic peptide. Furthermore, Ptdlns 3-kinase may be located directly upstream of protein kinase C or other protein kinases, which in turn activate the NADPH oxidase system.