Amalia Guaitani

Walker carcinoma 256: a model for studies on tumor-induced anorexia and cachexia.

Data on anorexia and cachexia induced by Walker carcinoma 256 in Sprague-Dawley rats were analyzed in order to standardize an experimental model using a statistical (nondeterministical) procedure for assessing the efficacy of potential orexigenic agents. This model was characterized by a mean survival time of 14 +/- 1 days and by food intake and body weight loss starting from day 6 after tumor implantation. The complex course of cachexia was characterized by reduction in the weight of gastrocnemius muscle and epididymal adipose tissue, taken as representative sites of loss of proteins and lipids.

Mechanism of maintenance of liver-specific functions by DMSO in cultured rat hepatocytes

The present study was undertaken to investigate the mechanism by which dimethylsulfoxide (DMSO) exerts its protective action on cytochrome P450-dependent activities and differentiation in cultured rat hepatocytes. Loss of cytochrome P450 is associated with a shortage of heme and reduced activity of delta-aminolaevulinic acid dehydratase: the addition of DMSO, which induces this enzyme in human hepatoma cells, is not able to affect it in hepatocytes in primary culture. DMSO is a strong scavenger of hydroxyl radicals and may destroy the reactive oxygen species formed under conventional culture conditions (i.e., 95% air and 5% CO2). In fact other powerful scavengers of oxygen radicals like dimethylthiourea, desferal, and catalase itself maintain higher levels of cytochrome P450 and higher activities of 7-ethoxycoumarin O-deethylase during 3 days of culture. DMSO and the other scavengers are also able to retain features of the morphological and biochemical differentiation of hepatocytes such as the ability to induce tyrosine aminotransferase activity in response to glucocorticoids.

Comparative kinetics of benz(a)anthracene, chrysene and triphenylene in rats after oral administration: I. Study with single compounds

Distribution and elimination of benz(a)anthracene (B(a)A), chrysene (Ch), and triphenylene (Tr) were compared after oral administration of the single compounds to 7-8-week-old female rats. These four-ring isomers were chosen because of their different carcinogenicity. The compounds have high affinity for lipid-rich tissues such as brain, mammary and parametrial adipose tissue. The relative availability of these compounds in the tissues examined decreased in the order Tr greater than B(a)A greater than Ch, but fecal elimination diminished in the opposite order Ch greater than B(a)A greater than Tr. Availability and fecal elimination of single polycyclic aromatic hydrocarbons (PAH) were influenced by the dose and concentration of PAH in the vehicle.

Protective effect of diosmetin on in vitro cell membrane damage and oxidative stress in cultured rat hepatocytes

Primary cultures of rat hepatocytes were used to study the effects of the flavonoids diosmin and its main metabolite diosmetin on the cell membrane damage caused by erythromycin estolate (EE) and oxidative stress caused by tert-butylhydroperoxide (TBHP). The damage was evaluated by the leakage of intracellular enzymes lactate dehydrogenase, aspartate-aminotransferase and the residual cell content of a lysosomal marker acid phosphatase (AP). After treating the cells for 40 h with diosmetin EE induced less enzyme leakage. The content of AP was kept higher by diosmetin pretreatment after 6 h exposure to EE. Diosmin at the same concentrations had barely any effect. Diosmetin, but not diosmin, also protected against TBHP toxicity and this was related to lower lipid peroxidation and higher glutathione content caused by pretreatment with the flavonoid. When the cells were treated simultaneously with TBHP and diosmetin after 21 h of culture, the protection by the flavonoid was even higher. In fact the antioxidant activity of diosmetin was considerably greater than that of diosmin. After 40 h exposure to both flavonoids diosmin but not diosmetin was detectable in the cell membrane fraction, suggesting that the latters protective effect is associated with its metabolites.

Bone Invasion by Walker 256 Carcinoma, Line A in Young and Adult Rats: Effects of Etidronate

Line A of Walker 256 carcinoma implanted in the muscle adjacent to the tibia of young (6 weeks) and adult (9 months) male rats invaded the bone. Osteolysis and reactive growth were greater in the bone of young animals than in adults. Ethane-1-hydroxy-1, 1-bisphosphonate prevented bone lysis and tumor invasion of the cortex both in young and adult animals. This model may be useful for studies of age-related differences in tumor infiltration into the bone and for investigating drug effects on this process.

Effect of etidronate disodium on the interactions between malignancy and bone

This study was designed to assess the capacity of etidronate disodium (etidronate) to affect neoplastic involvement of bone by murine tumors. Using sublines of the Walker 256 carcinoma, differing in the pattern of bone involvement, etidronate was found to inhibit hypercalcemia caused by systemically acting humoral factors, to inhibit bone metastasis following inoculation of tumor cells into the abdominal aorta, and to reduce the invasion of bone adjacent to tumors. Etidronate was also found to prevent bone metastasis in syngeneic rat mammary carcinoma. Etidronate was found devoid of direct antineoplastic activity, whether administered intramuscularly, subcutaneously, or intravenously, in a series of murine tumors of different histologic varieties. At the same time, it was shown that etidronate did not modify the antineoplastic activity of any of the major chemotherapeutic agents used in these studies, nor did it demonstrate any degree of immunosuppression. The experimental models used for this study should prove useful in evaluating agents that may affect the various types of bone involvement seen in neoplastic disease. The drugs apparent lack of interference with the antineoplastic activity of standard cytotoxic agents and its lack of immunosuppressive activity suggest that it may be readily adaptable to combination chemotherapy regimens.

Comparative kinetics of oral benz(a)anthracene, chrysene and triphenylene in rats: Study with hydrocarbon mixtures

Distribution and elimination of benz(a)anthracene (B(a)A) was compared in blood, liver, brain, parametrial adipose and mammary tissue of young female rats after oral administration of the polycyclic aromatic hydrocarbons (PAH) singly or in equimolar mixtures with chrysene (Ch) or triphenylene (Tr). The relative availability of B(a)A in tissues was not influenced by Ch or Tr in the mixture. However, the presence of B(a)A halved the relative availability of Tr and raised that of Ch. The relative availability of the three isomers decreased in the order Tr greater than B(a)A greater than Ch; this may be correlated to their solubility in water.

Pharmacokinetics of fotemustine and BCNU in plasma, liver and tumor tissue of rats bearing two lines of Walker 256 carcinoma

SummaryThe plasma and tissue pharmacokinetics of fotemustine (diethyl-1-[3-(2-chlorethyl)-3-nitrosoureido]-ethylphosphonate) and BCNU (1,3-bis-[2-chlorethyl]-1-nitrosourea) were investigated in healthy control rats and in animals bearing either the nitrosourea-sensitive line A (W256/A) or the nitrosourea-resistant line B (W256/B) of Walker 256 carcinoma. The antitumor activities of these nitrosoureas were similar following i.v. doses ranging from 10 to 40 mg/kg. For both drugs, the survival of tumor-bearing rats was lower in the W256/B than in the sensitive W256/A line. Some sex differences were observed, female rats being more responsive than males to both drugs. Nitrosourea concentrations were assayed in plasma and tissues by differential pulse polarography so as to assess whether the pharmacokinetics could explain the differences in antitumor activity. The antineoplastic effects of fotemustine seemed to be influenced by its pharmacokinetics. The plasma AUC of the intact nitrosourea was higher in females than in males. Fotemustine was cleared 2–5 times more slowly than BCNU from tumor tissue, and its clearance was higher in W256/B- than in W256/A-bearing rats. This suggests that the antitumor activity in the responsive line might partly be due to longer exposure of the growing tumor to the drug. The distribution volume of both nitrosoureas in plasma was higher in tumor-bearing animals than in healthy controls, indicating that the tumor tissue probably constitutes an additional distribution space.

Preservation of rat hepatic microsomal enzyme activities: Effect of low temperature and freeze-drying

About 30-70% of microsomal hydroxylation of aniline, 0-demethylation of 4-NO2-anisole, N-demethylation of aminopyrine, were lost when whole organs were frozen and kept at low temperatures (0 degrees, -20 degrees, -196 degrees C). When 9000 X g or 105000 X g fractions were prepared from fresh liver and subsequently frozen to different temperatures, there was little or no such loss of activity. The kinetics of the decrease in microsomal enzyme activities was followed during storage of frozen or freeze-dried microsomes at various temperatures. N-demethylation of aminopyrine appeared to be the most sensitive marker of microsome denaturation.

Effect of fasting, induction, sex and age on clearance of benz(a)anthracene and chrysene by isolated perfused rat liver

Hepatic clearances of benz(a)anthracene (B(a)A) and chrysene (Ch) by isolated perfused liver of female rats were similar when measured with hydrocarbons singly (B(a)A 4.3 ml/min, Ch 5.1 ml/min) or in a mixture (4.7 resp. 5.3 ml/min). Clearance of both isomers by livers from 24 h fasted donors was approximately halved. In vivo pretreatment with B(a)A (22.8 mg per kg for 2 days) significantly increased elimination of both hydrocarbons. Hepatic clearance of B(a)A was significantly higher in male rats than in females of the same age (8 weeks). Elimination of both hydrocarbons was significantly lower in 2 year-old males.