Long-term results of endoscopic removal of large colorectal adenomas

BACKGROUND AND STUDY AIMS

Endoscopic removal of large colorectal polyps has not been widely accepted. The aims of this study were to evaluate our longterm experiences justifying endoscopic resection technique as the treatment of choice.

PATIENTS AND METHODS

During a period of 12 years, 288 patients with a total of 302 polyps larger than 3 cm in diameter were treated endoscopically. 224 polyps were sessile and 78 pedunculated. Sessile polyps were removed using the piecemeal technique. Surgery was recommended in patients with unfavorable histology. Patients with favorable histology were followed up at 3 - 6 month intervals in the first year and then every 1 - 2 years.

RESULTS

A total of 184 patients with sessile polyps were followed up for at least 6 months. Recurrence rate of 166 benign polyps was 17 % (29/166). Only two patients had malignant recurrence. 8 of 18 patients with malignant polyps underwent surgery while 10 were unfit for surgery. 8 of these patients remained free of recurrence.

CONCLUSIONS

Previous concerns about endoscopic removal of large colorectal polyps are no longer justified. The results of this study showed that endoscopic resection of large colorectal polyps is safe and effective. In patients with high operative risk, endoscopic removal may be adequate.

Circumferential EMR and complete removal of Barrett's epithelium: a new approach to management of Barrett's esophagus containing high-grade intraepithelial neoplasia and intramucosal carcinoma

BACKGROUND

There is no study of circumferential EMR in patients with Barrett's esophagus containing early stage malignant lesions. This study investigated the effectiveness and safety of circumferential EMR by using a simple snare technique without cap.

METHOD

Patients with Barrett's esophagus containing multifocal high-grade intraepithelial neoplasia or intramucosal cancer, and patients with endoscopically nonidentifiable early stage malignant mucosal changes incidentally detected in random biopsy specimens were included in the study. A 30 x 50-mm polypectomy snare made of monofilament 0.4-mm steel wire was used without any additional device or submucosal injection.

RESULTS

Twelve patients (10 men, 2 women; median age 63.5 years, range 43-88 years) underwent circumferential EMR; 5 had multifocal lesions, and 7 had no visible lesions. Segments of Barrett's epithelium were circumferential (median length 5 cm) and completely removed. The median number of EMR sessions was 2.5. The median number of snare resections per EMR session was 5. The medial total area of mucosa in resected specimens per session was 3.8 cm(2). Two patients developed strictures that were successfully treated by bougienage. Minor bleeding occurred during 4 of 31 EMR sessions. During a median follow-up of 9 months, no recurrence of Barrett's esophagus or malignancy was observed.

CONCLUSIONS

Circumferential EMR with a simple snare technique is feasible, safe, and effective for complete removal of Barrett's epithelium with early stage malignant changes.

Variceal bleeding and portal hypertension: has there been any progress in the last 12 months?

A review of the literature on the management of esophagogastric varices published in the last 12 months shows that the data are still quite conflicting. In the primary and secondary prophylaxis of variceal bleeding, beta-blockers are still the mainstay of pharmacotherapy. Measurement of the hepatic portal venous pressure gradient is considered to be a reliable parameter for successful reduction of portal pressure using medical therapy. However, intolerance of propranolol requiring discontinuation of therapy has been observed in approximately 30 % of patients. Patients' compliance with medication may represent another drawback of medical therapy. The role of endoscopic band ligation in secondary prophylaxis is now indisputable, especially in comparison with sclerotherapy. In the primary prevention of variceal bleeding, band ligation is beginning to have a competitive edge over pharmacological therapy. Acute variceal bleeding is no longer a frequent morbid emergency. Most cases of bleeding can now be managed successfully with band ligation and N-butyl-2-cyanoacrylate obliteration. N-butyl-2-cyanoacrylate has come into increasingly widespread use in the treatment of bleeding gastric fundal varices in which surgery or transjugular intrahepatic portosystemic shunting were previously regarded as the preferred therapies.

Lipid-induced changes in vascular smooth muscle cell membrane fluidity are associated with DNA synthesis

In the present study, we examined whether changes in the membrane fluidity of vascular smooth muscle cells (VSMCs) alter their DNA synthesis. For this purpose, the membrane fluidity of the cells was modulated after treatment of VSMCs with 1,2-dioleoyl phosphatidylcholine (PC). Treatment of VSMCs with 1,2-dioleoyl PC-rich medium containing 10% heat-inactivated human serum and 3 mg/ ml 1,2-dioleoyl PC for 24 h resulted in an increase in VSMC membrane fluidity at all temperatures from 15 degrees to 40 degrees C as well as a 51% inhibition of DNA synthesis, compared with untreated cells. Remarkably, enrichment of VSMCs with 1,2-dioleoyl PC/cholesterol-rich medium containing 10% human serum, 3 mg/ml 1,2-dioleoyl PC and 2 mg/ml cholesterol restored both membrane fluidity and DNA synthesis to the levels of untreated cells. The present findings show an inverse association between increased membrane fluidity and cellular DNA synthesis.

Advances in interventional gastrointestinal endoscopy in colon and rectum

BACKGROUND

Instrumental and procedural advances particularly in the therapeutic field have been achieved.

REVIEW

Endoscopes with larger working channel, additional jet-channel, or variable stiffness allow more sophisticated interventional procedures. Higher resolution in endoscopic image quality helps to identify early lesions that can be treated endoscopically at this stage. Polypectomy and mucosectomy are no longer limited by the size of the lesion. Piecemeal technique is established, and a retrieval net is available for collecting all pieces obviating repeated introductions of the endoscope. In addition to snare polypectomy and mucosectomy, laparoscopy-assisted polypectomy and full-thickness resection are discussed. Self-expandable metal stents are used to decompress malignant colonic obstruction allowing for either preoperative bowel preparation and elective surgery or for noninvasive palliation. Argon plasma coagulation is an inexpensive and effective method for the treatment of bleeding from radiation proctitis.

Endoscopic treatment of biliary leakage with n-butyl-2 cyanoacrylate

BACKGROUND

Biliary leakage is a problematic complication of hepatobiliary surgery. A novel alternative method is described that can obviate the need for reoperation for refractory biliary fistula.

METHODS

Nine patients with large biliary leaks unresponsive to endoscopic drainage underwent N-butyl-2-cyanoacrylate glue occlusion at ERCP.

RESULTS

In 7 patients, occlusion was successful with prompt control of the fistula in a single session, averting reoperation. In 1 patient there was a partial response and in another the treatment was unsuccessful. No procedure-related complication occurred over a median follow-up of 35 months (range: 1.6-160 months).

CONCLUSION

N-butyl-2-cyanoacrylate glue occlusion is a safe and effective endoscopic method for control of refractory bile leaks that eliminates the need for surgical reintervention.

Impact of endoscopic ultrasound for evaluation of submucosal lesions in gastrointestinal tract

BACKGROUND

Endoscopic ultrasound is widely used following endoscopy for evaluation of suspected submucosal lesions and may guide further management of patients.

PATIENTS AND METHOD

A total of 181 consecutive patients with suspected submucosal lesion in the upper gastrointestinal tract were diagnosed by endoscopic ultrasound between 1990-97. We evaluated: 1) the potential of endoscopic ultrasound criteria to predict histological type of submucosal lesions in 69 patients with available histology, 2) the ability of endoscopic ultrasound alone or with clinical presentation, to predict malignancy in 86 patients with available histology or follow-up of >12 months.

RESULTS

Sensitivity and specificity for diagnosing 44 gastrointestinal stromal tumours were 95 and 72%, respectively, while 25 miscellaneous lesions were diagnosed correctly in only 56% by endoscopic ultrasound. Diagnosis of malignancy, using any two of three endoscopic ultrasound criteria (heterogeneous echotexture, size >3 cm, irregular margins) showed a sensitivity of 80% and specificity of 77%, giving accurate endoscopic ultrasound diagnosis in 16/20 malignant and 51/66 benign submucosal lesion. Heterogeneous echotexture, size >3 cm, and irregular margins showed a relative risk of 7.2, 5.4 and 4.6, respectively, for presence of malignancy. The presence of symptoms, potentially suggesting malignancy (dysphagia, gastrointestinal bleeding, pain and weight loss), had a relative risk of 4.2, however this did not increase the accuracy of diagnosing malignancy based on endoscopic ultrasound criteria alone.

CONCLUSION

The accuracy of endoultrasound is high in diagnosing gastrointestinal stromal tumours, which show a significant potential of malignancy. Endoscopic ultrasound morphology appears to be helpful in selection of patients for surgical or conservative treatment. The accuracy of endoscopic ultrasound in differential diagnosis of non-gastrointestinal stromal tumour lesions is limited.

A new radial mechanical puncture echoendoscope: prospective comparison with standard linear and radial echoendoscopes in assessment of focal pancreatic lesions

BACKGROUND

A new mechanical puncture-echoendoscope was evaluated by comparing it with conventional linear and radial echoendoscopes. The new instrument has a 300 degrees image field parallel to the axis of the echoendoscope, which could potentially improve accuracy and facilitate assessment of suspected pancreatic lesions before needle puncture.

METHODS

Twenty consecutive patients with suspected pancreatic lesions were evaluated endosonographically, including fine needle aspiration (FNA). The initial assessment was performed by random selection of either the new instrument or the standard linear echoendoscope. After completing the assessment including FNA, the procedure with FNA was repeated with the other puncture echoendoscope. The findings with these 2 instruments were compared to those with the conventional radial scanning echoendoscope.

RESULTS

FNA was performed in 17 patients with pancreatic head lesions. In 3 patients without a visible pancreatic mass lymph, nodes greater than 10 mm in diameter were aspirated. The ability to image the needle, number of punctures, and material obtained were comparable for both puncture echoendoscopes. There were no significant differences with regard to time required for FNA with both puncture echoendoscopes or in the assessment of surrounding structures with all 3 instruments. The results of cytopathologic evaluation of material obtained by FNA were similar in 15 cases. The new instrument could not be passed into the esophagus in 1 patient because of an esophageal stricture.

CONCLUSIONS

The performance of the new mechanical puncture echoendoscope was satisfactory for assessment and FNA of pancreatic lesions. The additional use of the conventional radial scanning echoendoscope provided no advantage with regard to any parameter assessed.

New mechanical puncture videoechoendoscope: one-step transmural drainage of a pseudocyst

A new mechanical puncture video echoendoscope (GF-UMD-240P 270 degrees image field parallel to the endoscope axis) has been used for puncture and drainage of a symptomatic pancreatic pseudocyst. It is equipped with a 2.8 mm working channel and an elevator allowing single step drainage with passage of a 7F nasocystic catheter.

Interventional endoscopic treatment of upper gastrointestinal bleeding - when, how, and how often

Acute upper gastrointestinal (GI) bleeding is still associated with high mortality. Reducing the rebleeding rate is the major challenge in therapeutic endoscopy. The following article describes the indications, techniques and limitations of endoscopic treatment of upper GI bleeding. Endoscopic techniques such as endoscopic sclerotherapy (EIS), endoscopic variceal ligation (EVL), cyanoacrylate obliteration, argon plasma coagulation (APC), and the application of hemoclip are described and compared concerning their efficacy. The pros and cons of "second-look" endoscopy are discussed.

Variceal bleeding and portal hypertension: still a therapeutic challenge?

In the primary prevention of variceal hemorrhage, beta-blockers continue to be the first-line treatment. Newer nonselective beta-blockers with anti-alpha1-adrenergic activity, such as carvedilol, appear to have a better impact on reducing the hepatic venous pressure gradient than propranolol. The addition of isosorbide mononitrate appears to improve the effectiveness of beta-blockers in primary prophylaxis, but not that of somatostatin in the treatment of acute variceal hemorrhage. The use of vasoactive drugs alone in acute variceal bleeding has not proved to be more effective than endoscopic treatment. The advent of endoscopic variceal ligation (EVL) has strengthened the role of endoscopy in the management of bleeding esophageal varices. EVL has improved the results, particularly in terms of lowering the treatment-related morbidity, compared with endoscopic variceal sclerotherapy (EVS). However, the variceal recurrence rate after initial eradication with EVL is relatively high. In contrast to synchronous combined therapy with EVL plus EVS, metachronous combination of EVL and low-dose EVS may improve the results of EVL alone. For bleeding fundic varices, obliteration using cyanoacrylate is currently the treatment of choice. Endosonography (EUS) is coming into more widespread use in the assessment of variceal eradication and in further attempts to improve the results of endoscopic injection therapy. According to two meta-analysis studies, transjugular intrahepatic portosystemic shunt (TIPS) is not yet capable of replacing endoscopic treatment in the secondary prevention of variceal bleeding.

Short-term stimulation of vascular smooth muscle cells with platelet-derived growth factor (PDGF)-BB and angiotensin II induces

Growth factors such as the platelet-derived growth factor (PDGF)-BB and angiotensin II (Ang II) have been shown to induce vascular smooth muscle cell (VSMC) proliferation after long stimulation periods. Little is known though, about the effects of PDGF-BB and Ang II on VSMC proliferation after short stimulation periods. The purpose of our study was to examine whether a short term (3-60 min) stimulation of VSMC with PDGF-BB or Ang II is sufficient to induce cell proliferation. Incubation of VSMC with Ang II (100 nM) or PDGF-BB (50 ng/ml) caused a significant increase in [3H]thymidine incorporation starting after a 3-min stimulation, while the cell counts required 32 and 8 h of stimulation, respectively. Mitogen-activated protein kinase activation reached a maximum at 5-10 min of PDGF-BB or Ang II stimulation. This study demonstrates that the growth-promoting effects of PDGF-BB and Ang II are strongly dependent on the length of the stimulation period and that while prolonged stimulation periods (>8-32 h) result in VSMC proliferation, short ones (3-60 min) result only in [3H]thymidine incorporation without an increase in cell count, a fact of considerable pathophysiological significance, considering that the time kinetics of growth factors in the VSMC microenvironment have not as yet been clarified.

Gangliosides GM1 and GM2 Stimulate Vascular Smooth Muscle Cell Growth and the Mitogen-Activated Protein Kinase Signaling Transduction Pathway

P156

The gangliosides GM1, GM2 and GM3 appear to be involved in the development of cardiovascular diseases. However, little is known about the direct effects of gangliosides on vascular smooth muscle cell growth (VSMC) growth and mitogenic signal transduction pathway. Stimulation of quiescent VSMCs with GM1 (5, 20, 50 and 100 μM) resulted in a dose-dependent increase in [ 3 H]thymidine incorporation from 41±3.5 (basal value) to 64±3.7, 69.6±7.1, 180±11 and 190±10.7 (mean±SE, n=3), respectively. GM3 (1 to 50 μM) had no effects on DNA synthesis whereas 100 μM GM3 caused a reduction in DNA synthesis from 41±3.5 to 12 ±1.4 cpm/μg protein (mean±SE, n=3). Stimulation of quiescent VSMCs with 50 μM GM1 and GM2 caused a 95±7% and 100±4% increase in cell counts (mean±SE, n=3) whereas 50 μM GM3 had no effects. Phosphorylated (activated) MAP kinases were detected by the enhanced chemiluminescence western blotting method using a phospho-specific extracellular signal-response kinases (ERK)1/2 antibody, a phospho-specific p38 MAPK antibody and a phospho-specific c-Jun N-terminal kinase/stress-activated protein kinases (JNK/SAPK) (the p54 and p46 isoforms) antibody. Stimulation of the cells with 50 μM GM1 and GM2 for 1 to 30 min resulted in time-dependent increase of phosphorylated ERK1/2 and p54/p46 with a maximum at 15 min (5-fold increase). The effect of GM1 and GM2 on the ERK1/2 and JNK/SAPK was also dose-dependent with maximal effect at 50 μM. Gangliosides had no effect on p38 MAPK phosphorylation. Treatment of the cells with 100 ng/ml pertussis toxin (PTX) (G i protein inhibitor) and 20 μM PD 98059 (MEK inhibitor) caused a complete inhibition of the phosphorylation of the ERK1/2 and JNK/SAPK. We conclude that the gangliosides may be involved in the development of cardiovascular diseases via proliferation of VSMCs. Furthermore, like bioactive lipids, gangliosides are able to stimulate the MAP kinase pathway via a PTX-sensitive G i coupled receptor.

Effects of Sphingosylphosphorylcholine on Vascular Smooth Muscle Cell Growth and on the Delayed Growth Response Cell Cycle Proteins Cdk2 and Cdc2

P160

Abnormal vascular smooth muscle cell (VSMC) proliferation plays an important pathophysiological role in the development of vascular disease. We examined the effect of Sphingosylphosphorylcholine (SPC) on DNA synthesis ([ 3 H]thymidine-incorporation method), cell number, cell volume, and cell diameter (CASY-1 coulter counter) as well as on the delayed response cell cycle proteins cyclin-dependent kinase2 (Cdk2) and Cdc2 (a serine/threonineprotein kinase) after stimulation of quiescent VSMCs with 5 μg/mL SPC for 2, 4, 6, 8, 12, 14, 16, 18, 20, 24, and 36 h. Cdk2 protein level is reduced when cells are in the G0-phase and its level is increased by the progression from G1- to S-phase upon addition of growth factors. Progression of the cells from the G2-phase (high level of tyrosine15-phosphorylated form of Cdc2) into M-phase is regulated by dephosphorylation of the Tyr15 residue of Cdc2 (34 kDa). Cdc2 phosphorylation status at Tyr15 and Cdk2 protein level were examined by chemiluminescence western blotting analysis using primary antibodies which recognizes Tyr15-phosphorylated Cdc2 and Cdk2 protein, respectively. Stimulation of VSMCs for 12, 14, 16, 18, 20, 24, and 32 h caused a 50±6, 50±11, 143±3, 192±15, 304±32, 221±29 and 245±26% increase in [ 3 H]thymidine incorporation. Stimulation of VSMCs with SPC for 24, and 32 hour resulted in an 8 and 32% increase in cell number. Cell volume and radius was increased by 40 and 11%, respectively. Stimulation of quiescent VSMCs with SPC for 12, 16, 20, 24 and 32 h caused an 7, 51, 50, 76, and 32% increase of Cdk2 level. After stimulation of VSMCs for 20 and 24 h a 91 and 103% increase of Tyr15-phosphorylation, respectively, occurred. An almost complete Tyr15-dephoshorylation occurred after 32 h. We might conclude that SPC is a potent mitogenic and hyperthrophic factor for VSMCs acting through stimulation of Cdk2 and Cdc2.

Cholera toxin treatment of vascular smooth muscle cells decreases smooth muscle alpha-actin content and abolishes the platelet-derived growth factor-BB-stimulated DNA synthesis

The second messenger cyclic AMP regulates diverse biological processes such as cell morphology and cell growth. We examined the role of the second messenger cyclic AMP on rat aortic vascular smooth muscle cell (VSMC) morphology and the intracellular transduction pathway mediated by platelet-derived growth factor beta-receptor (PDGF-Rbeta). The effect of PDGF-BB on VSMCs growth was assessed by [(3)H]-thymidine incorporation. Tyrosine phosphorylation of PDGF-Rbeta, PLC-gamma1, ERK1 and ERK2, p125(FAK) and paxillin as well as Sm alpha-actin was examined by the chemiluminescence Western blotting method. Actin mRNA level was quantitated by Northern blotting. Visualization of Sm alpha-actin filaments, paxillin and PDGF-Rbeta was performed by immunfluorescence microscopy. Cholera toxin (CTX; 10 nM) treatment lead to a large and sustained increase in the cyclic AMP concentration after 2 h which correlated with change of VSMC morphology including complete disruption of the Sm alpha-actin filament array and loss of focal adhesions. Treatment of VSMCs with CTX did not influence tyrosine phosphorylation of p125(FAK) and paxillin but decreased the content of a Sm alpha-actin protein. Maximal decrease of 70% was observed after 24 h of treatment. CTX also caused a 90% decrease of the actin mRNA level. CTX treatment completely abolished PDGF-BB stimulated DNA-synthesis although PDGF-Rbeta level and subcellular distribution and translocation was not altered. Furthermore CTX attenuated the PDGF-BB-induced tyrosine phosphorylation of the PDGF-Rbeta, PI 3'-K, PLC-gamma1 and ERK1/2 indicating an action of cyclic AMP on PDGF-beta receptor. We conclude that although cyclic AMP attenuates the PDGF-Rbeta mediated intracellular transduction pathway, an intact actin filament may be required for the PDGF-BB-induced DNA synthesis in VSMCs.

Green tea compounds inhibit tyrosine phosphorylation of PDGF beta-receptor and transformation of A172 human glioblastoma

The effect of the green tea compounds 2-(3,4-dihydroxyphenyl)-3, 4-dihydro-2H-1-benzopyran-3,5,7-triol (catechin), epicathechin (EC), epigallocathechin-3 gallate (EGCG), epicathechin-3 gallate (ECG) and catechin-3 gallate (CG) on the tyrosine phosphorylation of PDGF beta-receptor (PDGF-Rbeta) and on the anchorage-independent growth of A172 glioblastoma cells in semisolid agar has been investigated. Treatment of A172 glioblastoma with 50 microM CG, ECG, EGCG and 25 microM Tyrphostin 1296 resulted in an 82+/-17%, 77+/-21%, 75+/-8% and 55+/-11%, respectively (mean+/-S.D., n=3) inhibition of the PDGF-BB-induced tyrosine phosphorylation of PDGF-Rbeta. The PDGF-Rbeta downstream intracellular transduction pathway including tyrosine phosphorylation of phospholipase C-gamma1 (PLC-gamma1) and phosphatidylinositol 3'-kinase (PI 3'-K) was also inhibited. Spheroid formation was completely inhibited by 50 microM ECG, CG, EGCG and by 25 microM Tyrphostin 1296. We conclude that catechins of the green tea possessing the gallate group in their chemical structure act as anticancer agents probably partly via their ability to suppress the tyrosine kinase activity of the PDGF-Rbeta.

Early intracellular signalling pathway of ethanol in vascular smooth muscle cells

1. ERKs belong to MAP kinase family and are activated by several growth and stress factors. Although ethanol has been shown to modulate ERK1 and ERK2 (p44(mapk) and p42(mapk)) activity, it can also act as an antiproliferative agent in various mammalian cells. Since the nature of the antiproliferative effect of ethanol in VSMCs has not been defined, we examined its effects on growth and on early intracellular events normally induced by growth factors in VSMCs. 2. Measurement of cytosolic Ca(2+) and pH in cell monolayers was performed using fura-2/AM and BCECF/AM, respectively. The effect of ethanol on VSMCs growth was assessed by [(3)H]-thymidine incorporation, by cell counting and by determination of the caspase 3 activity. Stimulation of ERK1 and ERK2 was examined by the chemiluminescence Western blotting method. The expression of c-fos was quantitated by Northern blotting. Determination of inositolphosphates was performed after labelling of VSMCs with myo-[2-(3)H]-inositol and separation of inositolphosphates by HPLC. 3. Ethanol (0.3 - 1.0% v v(-1), 17 - 170 mM) induced a dose-dependent maximal stimulation of p44(mapk)/p42(mapk) at 30 min and expression of c-fos mRNA with a maximum at 120 min. Intracellular events upstream to MAP kinase, like an increase in [Ca(2+)](i), activation of the Na(+)/H(+) exchanger and formation of phosphoinositol metabolites were also markedly activated by ethanol. Treatment of VSMCs with ethanol for 3 - 5 min induced an increase in DNA synthesis whereas treatment of the cells for more than 30 min was toxic. Caspase 3 activity was not modulated by ethanol treatment of VSMCs. 4. We may postulate that the activation of these mitogenic signals including the elevation of DNA synthesis reflects a cell effort to protect itself against the toxic effects of ethanol.

Evidence that lipoproteins are carriers of bioactive factors

We recently demonstrated that the mitogenic effect of LDL (100 microg/mL) as well as its early intracellular signaling pathway are mediated by a pertussis-toxin (PTX)-sensitive G(i) protein-coupled receptor that is independent from its classical receptor and involves activation of extracellular response kinases (ERK1/2) (also known as p44(mapk)/p42(mapk)). In the present study we examined whether LDL-adherent factors may be responsible for some of the effects of LDL. The term "signaling activity" is used to characterize fractions that cause an increase in intracellular free Ca(2+) concentration or stimulate ERK1/2 and c-fos mRNA expression. LDL, HDL, and VLDL stimulate ERK1/2 with the following order of potency: LDL>HDL>VLDL. After delipidation of LDL with chloroform/methanol/water mixtures a PTX-sensitive signaling activity was found in one fraction arbitrarily called LDL-F. After further analysis of LDL-F compounds by high pressure liquid chromatography, a PTX-sensitive signaling activity was detected only in the fraction with a retention time of 33 minutes (arbitrarily called LDL-F33). Similarly, after separation of sphingosine-1-phosphate (SPP) and sphingosylphosphorylcholine (SPC) by high pressure liquid chromatography, a PTX-sensitive signaling activity was found in the fractions 33 and 33 to 35, respectively. These findings demonstrate that the effects of LDL-F33 are mimicked by similar fractions collected from SPP/SPC, hence suggesting that these LDL-adherent molecules are possibly closely related to SPP/SPC. A PTX-sensitive signaling activity was also detected in HDL and HDL-F33. Therefore, LDL and other lipoproteins may function as carriers for bioactive phospholipids thereby contributing to the development of coronary artery disease. Our findings support a new research concept that may contribute in elucidating cellular mechanisms promoting coronary artery disease.

Lysophosphatidic acid stimulates protein kinase C isoforms alpha, beta, epsilon, and zeta in a pertussis toxin sensitive pathway in vascular smooth muscle cells

The natural phospholipid lysophosphatidic acid (LPA) has been characterized as an important vascular smooth muscle cell (VSMC) mitogen whose effects are mainly mediated by pertussis toxin (PTX)-sensitive guanosine triphosphate (GTP)-binding protein (Gi-protein). Protein kinase C (PKC) isoforms play an important role in intracellular signaling cascades and in growth of VSMC. In the present study we investigated the effect of LPA on activation of PKC isoforms alpha, beta, epsilon, and zeta in VSMC by Western blot of cytosolic and membrane fractions. Furthermore, we examined the role of PKC activation on LPA-induced growth of VSMC using PKC inhibitor 19-27. Stimulation of VSMC by 5 microg/mL LPA for 10 min increased the amount of PKC alpha, beta, epsilon, and zeta in the particulate fraction by 689%, 285%, 424%, and 510%, respectively, and returned to control level after 30 min. Correspondingly, the amount of PKC alpha, beta, epsilon, and zeta in the cytosolic fraction decreased by 32%, 94%, 44%, and 95%, respectively, compared to control. Furthermore, we could show that LPA-induced activation of PKC alpha, beta, epsilon, and zeta isoforms was PTX sensitive. Incubation of VSMC with nonspecific PKC inhibitor 19-27 (10 micromol/L) for 24 h resulted in a 30% inhibition of LPA-induced DNA synthesis as measured by [3H]thymidine incorporation. In conclusion, in VSMC LPA stimulated translocation of PKC isoforms alpha, beta, epsilon, and zeta in a PTX-sensitive manner. Furthermore stimulation of PKC might be critically involved in LPA-induced mitogenesis in VSMC.

[Cushing syndrome with occult ectopic ACTH production]

A 19-year old patient was admitted to our hospital with the typical stigmata of a prolonged Cushing's syndrome. He presented first at another hospital with elevated ACTH values and the diagnosis of pituitary Cushing's syndrome was made. A partial hypophysectomy was performed, but neither this nor a therapy with ketokonazole could influence the cortisol levels. Because of this background the diagnosis of ectopic ACTH-production was established. Since we were not able to locate a source of ACTH, we recommended a bilateral adrenalectomy, after which the symptoms of Cushing's syndrome disappeared within a few months. About one year after the operation a CT-scan demonstrated an intrapulmonary mass, which was removed surgically. There were neither signs of local infiltration nor of lymphogenic metastasis. The histological and immunhistochemical diagnosis was typical of bronchial carcinoid with ACTH-production. The follow up so far did not reveal a recurrence.

Role of mitogen-activated protein kinase in the angiotensin II-induced DNA synthesis in vascular smooth muscle cells

The activation of mitogen-activated protein (MAP) kinase and increase in intracellular free calcium concentration ([Ca2+]i) are discussed in reference to activation of different protein kinases and growth of vascular smooth muscle cells (VSMCs). The aim of the present study was to investigate the role of angiotensin (Ang) II-induced increase in [Ca2+]i for activation of 44-kD/42-kD MAP kinase (p44mapk/p42mapk) and DNA synthesis in VSMCs. Experiments were performed by chelation of [Ca2+]i by the intracellular chelator 1,2-bis-(o-amino-5-methylphenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (MAPTAM). Ca2+ was measured by the fura 2 method. MAP kinase activation was determined by the Western blotting method. DNA synthesis was determined by measurement of [3H]thymidine incorporation into the cell DNA. Treatment of VSMCs with 20 micromol/L MAPTAM for 30 minutes resulted in a complete abolishment of the maximal Ang II-induced increase at 10 seconds. Ang II phosphorylated the p44mapk/p42mapk in a time-dependent manner, showing a maximum at 3 minutes. In MAPTAM-treated cells, the maximal phosphorylation of MAP kinase isoforms was shifted to 5 minutes, and dephosphorylation was delayed compared with untreated cells. In concordance with this finding, the induction of the MAP kinase phosphatase-1 was markedly impaired in MAPTAM-treated cells. Ang II induced a 2.3-fold increase in [3H]thymidine incorporation into DNA synthesis in untreated cells. This effect was not reduced in MAPTAM-treated cells. Treatment of the cells with PD 98059 (10 micromol/L), a MAP kinase kinase inhibitor, caused 85% inhibition of the Ang II-induced activation of MAP kinases but did not inhibit the Ang II-induced DNA synthesis. In conclusion, the Ang II-induced stimulation of the MAP kinase is a Ca2+-dependent process. Furthermore, blockade of the Ang II-induced stimulation of the early intracellular events, such as increase in [Ca2+]i or phosphorylation of the MAP kinase, is not accompanied by an inhibition of the Ang II-induced DNA synthesis.