Cholangiocarcinoma cell induced platelet aggregation via activation of thrombin and cyclooxygenase.

Objective: To investigate whether Cholangiocarcinoma (CCA) cells affected platelet aggregation via activation of thrombin and cyclooxygenase. Methods: Human Cholangiocarcinoma (HuCCA) cells were cultured in T-75 Flasks with a standard technique. Cells were grown to confluence until used, after which, cells were detached and then resuspended in DMEM. Resuspended HuCCA cells were assessed for their effects on inducing platelet aggregation of normal volunteers using Born’s technique. Hirudin, apyrase, EDTA and indomethacin were used as pharmacological tools to investigate signaling mechanisms. Results: HuCCA cells can initiate aggregation of platelets in heparinized platelet rich plasma (hPRP). The potency of HuCCA cell induced platelet aggregation depends on the concentration of cell suspension. Interestingly, HuCCA cell induced platelet aggregation was inhibited by hirudin (10, 20 and 40 unit), EDTA (2, 3 and 4 mM) and indomethacin (0.1, 1 and 2 mM) in a dose dependent manner but not by apyrase (5, 10 and 20 units). Conclusion: HuCCA cells can induce platelet aggregation possibly via activation of thrombin and the cyclooxygenase signaling pathway but not the ADP pathway. Calcium may be an important factor required for this reaction.

Expression of cyclooxygenase-1 and -2 in cultured human glioma cells of various stages.

Cyclooxygenase-1 (COX-1) and -2 (COX-2) are two isoforms of enzymes responsible for the biosynthesis of several forms of prostaglandins (PGs) from arachidonic acid. COX-1 is constitutively expressed in most normal tissues while COX-2 expression is regulated by certain stimuli such as cytokines and growth factors. The expression of COX-2 has been associated with many pathological conditions such as atherosclerosis, inflammation, and cancers (e.g. colon, breast, and lung cancers). COX-2 expression may be associated with the progression of cancers since PGE2, a major product of both isoforms was identified as a tumor-derived immune suppressor. Therefore, the suppression of COX-2 activity using specific COX-2 inhibitors (recently classified non-steroidal anti-inflammatory drugs) may delay the progression of tumors harboring COX-2. The search for tumors that highly express both isoforms of COX serves as a guide to target tumors that are most likely to be susceptible to treatment with specific COX-2 inhibitors. To study a homogeneous population of tumor cells, fifteen samples of primary culture cells were prepared from different human brain tissues and tumors collected from subjects operated on at Siriraj Hospital. Cells were grown to confluent in 75-cm2 tissue culture flask for about 4 weeks. After which time, cells were extracted to evaluate COX-1 and COX-2 protein expressions by immunoblot using specific antibodies. Four out of seven samples of glioblastoma multiforme cells strongly expressed COX-2, while all samples of examined cultured cells expressed COX-1. Cultured cells from astrocytomas had only faint staining for COX-2, while maintaining strong COX-1 expression. Thus COX-2 expression was limited to samples of glioblastoma multiforme, the most advanced stage of astrocytoma. Further study for the suppression of COX-2 activity in inducing tumor apoptosis and in improving cellular immunity against this advanced cancer should be elucidated.

A comparative study of the absorption and antiplatelet effect of aspirin-glycine vs baby aspirin.

Baby aspirin, due to its antiplatelet effects, is a drug of choice in the prevention of recurrent ischemic stroke. Since gastric irritation is a major problem in long term aspirin administration, aspirin-glycine has been developed to provide better bioavailability and efficacy. Aspirin-glycine, however, costs over twenty times more than baby aspirin, therefore, it is worthwhile comparing the efficacy of these two preparations of aspirin. We assessed absorption and antiplatelet effects f aspirin-glycine (100 mg ASA) and of baby aspirin (75 mg ASA) in 13 normal subjects) 5 men, 8 women, aged 25-63 years, mean 48 years). A single-blind cross-over design was used to compare the two treatments. A wash-out period of 2 weeks was applied. Blood samples were taken 4 times: before drug ingestion and at 5, 20 and 60 minutes after ingestion, to measure plasma slicylate levels and platelet aggregation. It was found that 5 minutes after aspirin-glycine ingestion plasma salicylate was detectable in 10 out of 13 subjects with X + SD = 4.92+ 2.54 mg%. At 20 and 60 minutes after ingestion plasma salicylate was detectable in all subjects with X+ SD = 5.14+ 1.82 and 5.76+ 3.33 mg% respectively. At 5, 20 and 60 minutes after ingestion of baby aspirin, plasma salicylate levels were detectable in only 6, 7 and 10 of the 13 subjects with X+ SD = 3.65+ 1.69, 3.67+ 1.61 and 4.28+ 1.62 mg% respectively. There was no significant difference between the two forms of aspirin regarding the inhibition of platelet aggregation. Side effects were not mentioned by any subjects during the experiment nor for two weeks thereafter.

Platelet serotonin in headache patients treated by new trend acupuncture.

Headache can be treated with acupuncture but its mechanism is virtually unknown. Since serotonin is considered to be an important factor as well as hyperactive platelets in the causation of migraine headache, a before and after study design was employed to evaluate the effects of acupuncture on the platelet serotonin and platelet aggregation in headache patients. Thirty-three patients, 18 suffering migraine headaches and 15 tension headaches were treated with dry needle acupuncture accompanying breathing exercise. Platelet serotonin was measured by spectrophotofluorometric method before and after treatment and found to be increased in 25 patients and decreased in 8 patients. The former groups show a statistically significant increase of p<0.01 (mean difference 0.15 + 0.26). Platelet aggregation induced by aggregating agents was also calibrated as to maximum response. The aggregations induced by collagen 1 ug, ADP 3 Um, adrenaline 1 or 25 uM, were decreased after acupuncture with significant collagen-induced aggregation (p<0.05). This suggests platelet serotonin and aggregation play a significant role in the treatment of headache by both inhibiting aggregation and by serotonin release. Thus the platelet serotonin is increased. Some interesting pints have been discussed in this report.