12(S)-HETrE, a 12-Lipoxygenase Oxylipin of Dihomo-γ-Linolenic Acid, Inhibits Thrombosis via Gαs Signaling in Platelets.

OBJECTIVE: Dietary supplementation with polyunsaturated fatty acids has been widely used for primary and secondary prevention of cardiovascular disease in individuals at risk; however, the cardioprotective benefits of polyunsaturated fatty acids remain controversial because of lack of mechanistic and in vivo evidence. We present direct evidence that an omega-6 polyunsaturated fatty acid, dihomo-γ-linolenic acid (DGLA), exhibits in vivo cardioprotection through 12-lipoxygenase (12-LOX) oxidation of DGLA to its reduced oxidized lipid form, 12(S)-hydroxy-8Z,10E,14Z-eicosatrienoic acid (12(S)-HETrE), inhibiting platelet activation and thrombosis. APPROACH AND RESULTS: DGLA inhibited ex vivo platelet aggregation and Rap1 activation in wild-type mice, but not in mice lacking 12-LOX expression (12-LOX(-/-)). Similarly, wild-type mice treated with DGLA were able to reduce thrombus growth (platelet and fibrin accumulation) after laser-induced injury of the arteriole of the cremaster muscle, but not 12-LOX(-/-) mice, supporting a 12-LOX requirement for mediating the inhibitory effects of DGLA on platelet-mediated thrombus formation. Platelet activation and thrombus formation were also suppressed when directly treated with 12(S)-HETrE. Importantly, 2 hemostatic models, tail bleeding and arteriole rupture of the cremaster muscle, showed no alteration in hemostasis after 12(S)-HETrE treatment. Finally, the mechanism for 12(S)-HETrE protection was shown to be mediated via a Gαs-linked G-protein-coupled receptor pathway in human platelets. CONCLUSIONS: This study provides the direct evidence that an omega-6 polyunsaturated fatty acid, DGLA, inhibits injury-induced thrombosis through its 12-LOX oxylipin, 12(S)-HETrE, which strongly supports the potential cardioprotective benefits of DGLA supplementation through its regulation of platelet function. Furthermore, this is the first evidence of a 12-LOX oxylipin regulating platelet function in a Gs α subunit-linked G-protein-coupled receptor-dependent manner.

Small-cell neuroendocrine carcinoma as a variant form of prostate cancer recurrence: a case report and short literature review.

BACKGROUND: Small-cell neuroendocrine carcinoma has been recognized as a rare histologic variant occurring in only 0.5% to 2% of prostatic primary tumors. However, recent autopsy studies suggest development to this phenotype in up to 10% to 20% of the cases with hormone-refractory disease. CASE PRESENTATION: A case of conventional adenocarcinoma before androgen-ablation therapy but showing progression to small-cell neuroendocrine carcinoma at the recurrence. The immunohistochemistry of the tumor showed strong positive staining for progastrin-releasing peptide (ProGRP), a carboxy terminal region common to 3 precursors for gastrin-releasing peptide, but almost negative staining for chromogranin-A and prostate-specific antigen. Combination chemotherapy based on cisplatin and etoposide was effective for controlling the tumor progression for 7 months, and the serum ProGRP level correlated well to the clinical course. Neither objective nor subjective responses were observed to somatostatin analogue therapy performed in the late stage of disease. CONCLUSIONS: The present case reminds the urologist that small-cell neuroendocrine carcinoma may be a variant form of disease recurrence during androgen ablation in advanced prostate cancer. A strategic approach for this phenotype evaluating serum neuroendocrine markers, such as ProGRP, should be taken when serum prostate-specific antigen does not reflect the disease state. This approach would allow one to choose alternative therapies targeting neuroendocrine cells other than androgen ablation.

Selenium and prevention of prostate cancer in high-risk men: the Negative Biopsy Study.

Epidemiological and clinical studies suggesting a significant inverse relationship between intake of dietary selenium and overall cancer risk have led to initiation of a randomized, placebo-controlled, phase III clinical trial testing the safety and efficacy of selenized yeast as a chemopreventive agent for prostate cancer. Participants eligible for the 'Negative Biopsy Study', which was initiated in August 1999, are men considered to be at high risk for prostate cancer because of at least one negative sextant prostate biopsy, which was clinically indicated within 1 year of enrollment to the study. After a 30-day run-in period to ensure protocol compliance, participants are randomized to receive either 200 or 400 microg selenized yeast or matched placebo once daily. Primary study endpoints include development of prostate cancer and prostate-specific antigen (PSA) velocity. Secondary biochemical endpoints include change in chromagranin A and alkaline phosphatase. As of 1 June 2003, 514 eligible participants had been enrolled. Randomization schema was effective for selected parameters including age, body mass index, smoking status, baseline PSA and baseline plasma selenium level. Various data, including medical history, family history, and urological symptoms and specimens (including blood and subsequent prostate biopsy samples) had been collected at baseline, and throughout both the intervention and follow-up stages of the protocol. The goal for accrual is 700 evaluable participants.

Serum pancreastatin levels predict response to hepatic artery chemoembolization and somatostatin analogue therapy in metastatic neuroendocrine tumors.

INTRODUCTION: Neuroendocrine tumors often metastasize to the liver and present with disabling hormonal symptoms. Hepatic artery chemoembolization (HACE) combined with somatostatin therapy, pre-embolization, peri-embolization and post-embolization, at doses to control symptoms, is an aggressive approach that can relieve hormonal symptoms with minimal morbidity and mortality. METHODS: Chemoembolization was performed using 30 mg of adriamycin, 50 mg of mitomycin, 12 ml of hexabrix, 10 ml of ethiodol, and 360-500-microm particles. Pancreastatin, a split product of chromogranin A, was measured pre-HACE and post-HACE in all patients. RESULTS: Forty-three chemoebolization procedures were performed in 34 symptomatic patients from December 1995 to August 1999. Seventeen patients had intestinal primaries (50%), seven had pancreatic primaries (20%), five had bronchial primaries (15%), and five had unknown primaries (15%). Systemic pancreastatin levels were improved or stable in 31 patients (78%). Symptoms were improved in these 31 patients (78%). Systemic serotonin levels were improved or stable in 24 patients (60%). Radiographic improvement or stability was seen in 18 patients (45%). Procedural related morbidity included pain, fevers, nausea, vomiting, and transient elevations of liver function studies in 75-100% of patients. There was one procedural related mortality (2%). Less than 20% improvement in pancreastatin levels from baseline was associated with death in five of five patients (100%). This was not observed with serotonin levels. CONCLUSION: Measurement of serum pancreastatin levels is an easy and useful method to predict success in patients who undergo HACE plus somatostatin therapy for metastatic neuroendocrine tumors to the liver. This therapeutic approach is effective in relieving symptoms in 78% of patients, with minimal major morbidity or mortality.

[Interstitial laser hyperthermia of gastrinoma liver metastases in a child]. / Interstitielle Laserhyperthermie von Gastrinomlebermetastasen beim Kind.

Ultrasound-guided, laser-induced thermocoagulation with Nd:YAG laser (1064 nm) was performed in a child with metastatic gastrinoma disease. The emitted laser energy to coagulate a radius of 15-20 mm of metastatic liver tissue was 4 W with a duration time of 300 s. Marked reduction of gastrin was observed after interstitial laser hyperthermia.