CO2 Microbubbles Research Articles

Application of Supercritical CO2 Bubbling to Inactivate E. coli and Coliform Bacteria in Drinking Water

The effect of the continuous flow of supercritical CO2 microbubbles (the SC-CO2 method) on the inactivation of both Escherichia coli in model water and coliform bacteria in water prior to treatment at a municipal water filtering plant were studied as a way to produce safe drinkable tap water. The number of surviving cells in both samples drastically decreased above a certain concentration of dissolved CO2 (γ=25). When treated for 13.3min, cells were not detected at concentrations over γ=30. The dependences of the number of surviving cells on the concentration of dissolved CO2 were similar in both the treatments for 6.7 and 13.3min. Therefore, it was suggested that effective inactivation could be achieved by minimizing the treatment time. From these results, it was proposed that the SC-CO2 method might be effective in inactivating E. coli and coliform bacteria for the production of public drinking water.

Significance of tumor vascularity as a predictor of long-term prognosis in patients with small hepatocellular carcinoma treated by percutaneous ethanol injection therapy.

We estimated the significance of the vascularity of small hepatocellular carcinoma (HCC) as a predictor of long-term prognosis in patients treated with percutaneous ethanol injection therapy (PEIT/PEI). Fifty-four patients who have been followed-up in our hospital and who had HCC less than 20 mm in diameter were observed for 199 to 2074 days. Hepatic angiography (digital subtraction angiography; DSA and ultrasound angiography with intraarterial CO2 microbubbles; USAG) was performed before treatment in all cases, and the vascularity of the tumor was clinically evaluated. The survival rate was analyzed according to this vascularity. Of the 54 tumors, 24 had tumor stain on DSA, while 30 did not, and 38 showed enhancement on USAG, while 16 did not. The 3- and 5-year survival rates were 48.7 and 34.1% and 89.7 and 69.7% of patients with negative staining HCC (p = 0.0723). The rates were 48.6 and 36.7%, respectively, of patients with positive enhancement HCC on USAG, and both rates were 85.7% of patients with negative enhancement HCC (p = 0.0231). Tumor vascularity will play a role in the long-term prognosis of these patients with small HCC when they are treated with PEIT/PEI.

ETIOLOGY, SCREENING, AND TREATMENT OF HEPATOCELLULAR CARCINOMA

The prognosis with large hepatocellular carcinomas is poor, and only palliative treatment is available. Small tumors are amenable to several modes of treatment, including liver transplantation, resection, or alcohol injection, with acceptable 5-year survival rates. Although the value of screening for hepatocellular carcinoma has yet to be shown, these data, coupled with the recognition of at-risk groups and useful diagnostic techniques, might encourage the clinician to screen at-risk patients in the clinic. New imaging techniques such as ultrasonographic angiography enhanced with CO2 microbubbles, or color Doppler ultrasound, may clarify the intratumoral blood flow of small tumors.

Extended intraarterial cisplatin infusion for treatment of gynecologic cancer after alteration of intrapelvic blood flow and implantation of a vascular access device.

Twenty-two patients with advanced gynecologic cancer underwent extended intraarterial cisplatin infusion after alteration of the intrapelvic blood flow and implantation of a vascular access device (VAD). To maximize concentrations of cisplatin at the target lesion, the superior and inferior gluteal arteries were embolized with steel coils. The tip of the catheter was inserted into the internal iliac artery; the opposite end of the catheter was connected to the VAD. Intensive radioisotope accumulation was demonstrated in the anterior division of the pelvis, seen by scintigraphy performed with technetium 99m macroaggregated albumin via the VAD. Local perfusion in the tumor was well seen by ultrasonographic angiography with CO2 microbubbles via the VAD. Continuous consecutive infusion of cisplatin at a rate of 12.5 mg/day via the VAD minimized the toxicity. The overall response rate was 73%. Radical surgery was possible in 16 of the 22 patients after this intraarterial infusion. This method was useful for treating advanced gynecologic cancer without significant toxicity.

Detection of Hepatocellular Carcinoma by Intraarterially Enhanced Ultrasonography with Co2Microbubbles

Purpose: To evaluate the diagnostic value of contrast-enhanced US with CO2 microbubbles (EU) for HCCs. Detectability was compared with DSA, dynamic CT, and Lipiodol CT.Material and Methods: Forty-seven histologically proven HCCs detected with US were evaluated with EU, DSA, and dynamic CT. In 23 patients (35 lesions), Lipiodol CT was also performed. The size of the tumors ranged from 8 to 71 mm (average 28.1 mm); 24 lesions were smaller than 20 mm and 23 lesions were larger than 20 mm.Results: Overall detection was possible in 40 of 47 lesions (85%) by EU, in 32 of 47 (68%) by DSA, in 33 of 47 (74%) by dynamic CT, and in 27 of 35 (77%) by Lipiodol CT. In tumors smaller than 20 mm, detection was possible in 21 of 24 lesions (88%) by EU, 14 of 24 (58%) by DSA, 14 of 24 (58%) by dynamic CT, and 11 of 17 (65%) by Lipiodol CT.Conclusion: EU has significant diagnostic value for detection of HCCs, particularly tumors smaller than 20 mm.