Effect of acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on humoral antibody production in mice

The effect of single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 1.2, 6 or 30 micrograms/kg i.p.) on primary humoral antibody production was studied in young adult C57 BL/6J mice. TCDD profoundly suppressed the primary response to thymus-dependent (sheep erythrocytes) and independent (type III pneumococcal polysaccharide) antigens. The inhibitory effect of TCDD was still detectable 42 days after treatment. In contrast, under these experimental conditions, in vitro lymphoproliferative responses to Concanavalin A (Con A) and bacterial lypopolysaccharides and the ability to mediate graft versus host reaction were not significantly affected per unit number of lymphoid cells.

Carnitine balance in hemodialyzed patients

1-Carnitine was assayed before and after dialysis in plasma, dialyzate and muscle of four patients undergoing hemodialysis. The findings suggest that plasma carnitine losses occurring during hemodialysis may be at the expense of the carnitine present in extracellular fluid. Carnitine concentrations in muscle of hemodialyzed patients and controls did not differ significantly. Chronic carnitine administration did prevent plasma carnitine from falling below base levels, but did not affect muscle concentration.

Divergent effects of macrophage toxins on growth of primary tumors and lung metastases in mice

The effects of silica and carrageenan on primary tumor growth and metastases were evaluated in c57bl/6 and BALB/c mice transplanted with the poorly immunogenic Lewis lung (3ll) carcinoma, mFS6 sarcoma and Madison 109 carcinoma spontaneously metastasizing to the lungs. Silica and carrageenan significantly enhanced lung metastases and decreased primary tumor weight in all three experimental models. A similar augmentation of lung secondaries was found after i.v. inoculation of 3LL tumor cells. The effects of carrageenan on primary 3LL tumor growth and metastases were observed also in thymus-deprived animals. The effect of macrophage toxins was studied also in C57BL/6 mice transplanted with the M5076/73A ovarian carcinoma. This tumor spontaneously metastasizes to various abdominal organs, but not to the lung. After treatment with carrageenan, lung metastases were observed, but no effect on secondaries at other anatomical sites or on the primary tumor was detectable. It is suggested that host defense mechanisms impaired by silica and carrageenan may have divergent effects in the regulation of growth of some primary tumors and spontaneous lung metastases.

Monosodium glutamate kinetic studies in human volunteers

(a) A kinetic study of plasma glutamic acid (GA) was made after monosodium glutamate (MSG) administration to human volunteers. MSG was given at doses of 30,60 and 120 mg/kg in a bouillon and of 60 mg/kg in tomato juice. In another experiment a normal meal was consumed without added MSG. (2) Plasma area under the curve (AUC) was found to be lower in females than in males. (3) Plasma AUC was lower when MSG was taken in tomato juice than when consumed in bouillon. (4) Consumption of the normal meal did not result in any significant increase in plasma GA.

Time dependence of the in vitro cytotoxicity of hexamethylmelamine and its metabolites

The cytotoxicity of hexamethylmelamine (HMM) and its metabolites pentamethylmelamine (PMM), N,2,2,4,6-tetramethylmelamine (TMM) and hydroxymethylpentamethylmelamine (HMPMM) and of the alkylating agent triethylenemelamine (TEM) were studied on a cell line derived from a human ovarian cancer, by measuring [3H]TdR uptake. After 24 h of incubation all the tested compounds inhibited [3H]TdR uptake, but only at a concentration of 100 micrograms/ml. However, after 120 h incubation, concentrations of 0.1--10 micrograms/ml resulted in highly significant cytotoxicity. HMPMM and TEM were the most active and their effect was not reversed 72 h after their removal. In our in vitro system no metabolism of HMM was observed.

Comparison of the effects of the stereoisomers of fenfluramine on the acetylcholine content of rat striatum, hippocampus and nucleus accumbens

The (+)- and (-)- isomeric forms of fenfluramine were compared for their effects on rat brain area acetylcholine (ACh) content. The drugs showed similar patterns in increasing ACh content in the accumbens and hippocampus and in being ineffective in the brainstem. The actions differed in the striatum where the (+)-form markedly increased ACh content while the (-)-form produced no change. Both isomer-induced increases in ACh in the accumbens were prevented when 5-HT synthesis was blocked by p-chlorophenylalanine, thus denoting 5-hydroxytryptaminergic mediation of these effects. In striatum, the increase in ACh induced by (+)-fenfluramine was summated with the increase in ACh induced by dopamine receptor stimulation with apomorphine and was not prevented by dopamine receptor blockade with pimozide. On the other hand, apomorphine's effect was blocked by (-)-fenfluramine while pimozide pretreatment unmasked an increase in ACh induced by (-)-fenfluramine. The results favour the notion that there is a population of cholinergic neurons intrinsic to the striatum which is under inhibitory 5-HT regulation and independent of inhibitory dopamine regulation.

Neuronal links in the CNS: focus on dopaminergic and serotonergic regulation of striatal cholinergic neurons

The paper reviews the previous data of the authors on the links between dopamine and acetylcholine and serotonin and acetylcholine systems in the striatum. The results of studies in which the effects of alteration of dopaminergic and serotonergic transmission on striatal acetylcholine level were assessed, indicate the presence of two independent striatal cholinergic neuron populations, one of which is under inhibitory control of serotonergic, and another--of dopaminergic system.

Plasma glutamic acid levels in premature newborn

24 premature, newborn infants were investigated for plasma glutamic acid (GA) levels before and after a normal milk feed, to ascertain if the ingestion of GA present in the milk could result in an increase of its plasma level. No increases were detected in plasma between 5 and 90 min after the feed. These results may be important in respect to the problem of the possible toxicity of monosodium glutamate (MSG) added to baby foods.

In vitro effects of saccharin on cell-mediated host defence mechanisms

In vitro exposure to saccharin (0.1-2 mg/ml) did not affect the tumoricidal activity of macrophages and natural killer (NK) cells from mice and rats. In contrast saccharin at doses of 0.5-2 mg/ml significantly and consistently depressed the blastogenic response of rat lymph node cells to phytohemagglutinin (PHA). Similarly mouse splenocytes showed impaired responsiveness to PHA and bacterial lipopolysaccharides n the presence of 2 mg/ml saccharin. Compared with murine lymphoid cells, human peripheral blood lymphocytes were relatively resistant to the immunodepressive activity of saccharin, a low but significant, depression (21%) of the response to PHA being observed only at the highest concentration (2 mg/ml) in 1 of 3 normal healthy donors tested.

Accumulation and metabolism of uneven fatty acids present in single cell protein

Liquipron and Toprina, obtained by growing yeasts (Candida maltosa and Candida lipolytica) on n-hydrocarbons, were investigated to ascertain the biological significance and possible toxicological implications of their high content of uneven fatty acids (UFA). It was confirmed that the extent to which UFA accumulate in adipose tissue of rats fed the 2 products reflects only partially their UFA contents. The presence of UFA in rat tissues does not appear to alter intermediate metabolism. The capacity of liver mitochondria ot oxidize palmitic acid was similar in control and in Liquipron-treated rats. Palmitic acid and heptadecanoic acid did not compete for oxidation when mixed at concentrations which reflect their presence in the tissues of animals fed high levels of Liquipron.

Species differences in clobazam metabolism and antileptazol effect

The antileptazol effect of clobazam lasts longer in the mouse than in the rat. After intraperitoneal injection of clobazam (10 mg kg-1) plasma and brain concentrations of the drug and its rate of disappearance were similar in both species, whereas the metabolite N-demethylclobazam was present at higher concentrations and for longer in the mouse than in the rat. Although the exact contribution of the N-desmethylclobazam to the anticonvulsant effect of clobazam cannot be assessed, the longer duration in mice than in rats seems to be associated with different brain accumulations of the metabolite.

Pharmacological activities of clobazam and diazepam in the rat: relation to drug brain levels

Brain distribution and various pharmacological effects of clobazam and diazepam were studied in rats. When given at 10 mg/kg i.p. the compounds reached peak brain levels 15 min after injection, and showed similar half lives. At peak time brain levels were proportional to the dose administered. Very little of the N-desmethylmetabolite of each compound was found in the brain. Clobazam was less effective than diazepam in protecting rats from pentetrazol convulsions. Disrupting rota-rod performance and increasing punished responses in a "conflict" test, the relative potencies ranging from 4 to 8 in the various tests. The results are discussed in relation to the importance of animal species selection for predicting favourable therapeutic effects in humans.

The effect of acute administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on humoral antibody production and cell-mediated activities in mice

The effect of single doses of TCDD (1.2, 6 or 30 gamma/kg) on several immune parameters has been investigated in young adult C57B1/6 mice. TCDD profoundly suppressed the primary and secondary humoral response to T-dependent (sheep erythrocytes, SRBC) and T-independent (Type III pneumococcal polysaccharide, S III) antigens. In vitro lymphoproliferative responses to Concanavallin A (Con A) and bacterial lypopolysaccharide (LPS), and macrophage and natural killer (NK) cell-mediated cytotoxicity were not significantly affected per unit number of lymphoid cells. Moreover, the ability of splenocytes from TCDD treated animals to mediate a graft versus host (GVH) reaction was not impaired.

Pharmacokinetic approach to in vitro testing of ovarian cancer cell sensitivity

Cell populations obtained from ovarian cancer specimens were seeded in primary culture and morphologically identified as cancer cells. Methotrexate, cytosine arabinoside, 5-fluorouracil, antinomycin D, melphalan, and adriamycin were added to the culture medium at different concentrations and for various periods of time. The results are discussed in relation to the pharmacokinetic availability of drugs in the plasma compartment of patients treated by different therapuetic regimens. Totally inactive drugs can be identified by comparing plasma levels with active concentrations while for drugs active in vitro at concentrations in the range of pharmacokinetic levels, the percentage of responders among patients might be explained by the intrinsic variability of cancer cells.

Limits of animal models in cancer chemotherapy

In animals models used in cancer chemotherapy, there is a low variability in terms of sensitivity of cancer cells in vitro, plasma levels of anticancer drugs, and interhost immune responses. In contrast, human tumors (e.g., ovarian carcinoma) show much greater variability. It is suggested that greater attention should be given to the study of the variables which distinguish the clinical setting from the animal models.

2,3,7,8-Tetrachlorodibenzo-p-dioxin toxic effects and tissue levels in animals from the contaminated area of Seveso, Italy

After the environmental contamination by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the area of Seveso, Italy, thousands of small domestic animals (mainly rabbits and poultry) died within a few weeks. Autopsies on dead animals showed various pathological signs, such as hepatic lesions and haemorrhage. TCDD was monitored in animal tissues by gas chromatography-mass fragmentography; rabbit liver levels corresponded fairly well to soil contamination, which indicated that this species can be used as a tool for tracking the presence of TCDD in the environment.