Biomedical subjects

P Naredi

Publications and source records attributed to P Naredi.

41 records · Page 3Linked to original sources

PubMedDate not supplied

Blood flow in liver tumors--effects of vasoactive drugs estimated with xenon (133Xe) clearance.

BACKGROUND/AIMS: The aim of the present study was to identify in a standardized experimental rat liver tumor system the drugs which are most appropriate in influencing the relationship between liver tumor and normal liver parenchyma blood flow as estimated with 133Xe washout clearance method, and thereby positively influencing the kinetics of chemotherapeutic drugs. A battery of vasoactive drugs, which according to a literature review were considered to be active, were tested. METHODOLOGY: Twelve drugs were administered intravenously on 113 Wistar-Fu rats with an experimental adenocarcinoma in the liver (weight 0.62 g). 133Xe was applied in the tumor and in normal parenchyma with and without administration of a vasoactive drug. The pulses were registered with a NaI (Tl)-scintillation detector connected to a multichannel analyzer. The disappearance rate of the isotope was calculated according to a single compartment model. Four recordings were performed in each rat randomly in tumor and liver parenchyma with and without a drug (series A) and one series twice in tumor and twice in parenchyma with a drug (series B). RESULTS: In unaffected animals the tumor to liver quotient was 0.57+/-0.35. This quotient was higher in tumors less than 0.53 g. Angiotensin-II 8 mg i.v. increased the quotient to 0.95+/-0.20. No other drug significantly influenced the quotient. CONCLUSIONS: In an experimental adenocarcinoma in the liver this study has investigated the possibility of increasing the tumor to normal liver parenchyma blood flow quotient by a variety of vasoactive substances for the beneficial modification of tumor blood flow. Angiotensin II 8 mg i.v. was the only drug, which increased the quotient. None of the other tested drugs were supporting previous presented results on influencing tumor blood flow.

Animals↗

PubMedDate not supplied

133Xe clearance estimates the effect of vasopressin on peritoneal blood flow in rats.

BACKGROUND/AIMS: When assessing the peritoneal microcirculation with invasive methods, interference with the mechanisms of vaso-regulation may occur. The 133Xe clearance technique renders the possibility, by minimal invasiveness, to estimate the influence of a vasoactive agent on the peritoneal microcirculation. METHODOLOGY: Ten to 15MBq of 133Xe were injected in the abdominal cavity in thirty-eight Wistar-FU (W-FU) rats and 35 Lister-Hooded (LH) rats. A NaI (Tl)-scintillation detector registered activity before and during vasopressin infusion. Gamma camera imaging confirmed the washout from the abdominal cavity. The laser Doppler flowmetry technique was used as a comparison. RESULTS: Vasopressin at 0.07 IU/kg/min IV significantly reduced 133Xe-clearance by 37% (p = 0.029) and 52% (p=0.036) and laser Doppler flowmetry by 69% (p=0.0019) and 44% (p=0.0039) in W-FU and LH rats, respectively. A linear correlation between dose of vasopressin and relative decrease in 133Xe clearance was demonstrated in the W-FU rat model (r2=0.98, p=0.023). The 133Xe clearance from the abdominal cavity in rat using a single-compartment model or the slow compartment in a double-compartment model gave reproducible information. CONCLUSIONS: The usefulness of this mini-invasive technique for sequential measurements before and during intervention will render the 133Xe clearance suitable for assessment of blood flow changes in the abdominal cavity.

Animals↗

PubMedDate not supplied

Cytotoxicity of liver macrophages against liver tumours. Influence of betamethasone, indomethacin and allopurinol.

Macrophage activation with zymosan has an inhibitory effect on tumour take and initial tumour growth in the rat liver. 91 rats with syngeneic transplanted hepatoma in the liver were treated with zymosan (46) or saline (45). Betamethasone (glucocorticoid), indomethacin (prostaglandin synthesis inhibitor), allopurinol (oxygen radical scavenger) or saline were administered concomitantly. Tumour take, tumour growth and relative spleen weight were used as in vivo parameters of liver macrophages cytotoxicity and general macrophage activation. Zymosan inhibition of tumour take was counteracted by betamethasone, indomethacin and allopurinol. Betamethasone increased the growth rate of the non-zymosan treated tumours during seven days. Indomethacin decreased the growth rate of the tumours in non-zymosan treated rats up to 14 days. Allopurinol significantly blocked the zymosan inhibition of tumour take and tumour growth after 7 and 14 days. Allopurinol blocked zymosan induced increased relative spleen weight. It is proposed that the liver macrophage cytotoxicity induced by zymosan is in part mediated via production of oxygen radicals.

Allopurinol↗

PubMedDate not supplied

Intratumoral distribution of microspheres.

Fifteen mu carbonized microspheres injected in two transplantable rat tumors, a hepatoma transplanted to the dorsum of one hindpaw and an adenocarcinoma transplanted into the liver, were found to be unevenly distributed and often in aggregates that seemed to fill intratumoral vessels. This finding can partly explain the increased vascular resistance in tumors after microsphere injection and makes the technique with repeated injections of microspheres disputable.

Animals↗

PubMedDate not supplied

Biochemical modulation of intraperitoneal fluorouracil by allopurinol-the effect on an experimental adenocarcinoma in the liver.

In a rat liver tumour system with a nitrosoguanidine-induced carcinoma and in an in vitro system with the same tumour, the effect of allopurinol on the toxicity and antitumour effect of 5-fluorouracil (5-FU) was explored. Two doses of 5-FU, 30 and 60 mg/kg b.w. intraperitoneally (i.p.), were tested with a large dose of allopurinol subcutaneously (s.c.( (300 mg) in rats. The drugs were given for three consecutive days. The lethal toxicity of 60 mg 5-FU i.p. could not be counteracted by allopurinol. Allopurinol and 30 mg 5-FU reduced the tumour growth rate more than 5-FU alone. The spleen was smaller, as a sign of increased toxicity, without allopurinol. The concentration of allopurinol and its metabolites in the general circulation was high. In vitro, there was no additive or specific effect of allopurinol. These results indicate some in vivo metabolic modulation of 5-FU efficacy by allopurinol if 5-FU is administered intraperitoneally and allopurinol systemically.

Adenocarcinoma↗