Influence of dendritic cells on tumor growth

Dendritic cells (DC) exposed to antigen are potent initiators of immune responses, and the numbers of DC and the dose of antigen control the level of response. The influence of these variables was tested on the growth of mouse sarcoma cells in vivo. When normal syngeneic DC (100,000) were given to mice with palpable tumors, tumor regression or delay in tumor growth was obtained. DC exposed to increasing doses of tumor extract in vitro before administration had progressively less effect. DC exposed to antigen delayed tumor growth significantly only when given on the same day as 500 tumor cells. The studies suggested that low doses of antigen on DC elicit immune responses and that high doses block them. The numbers of antigen-presenting cells and the dose of antigen modulate the degree of immunity to mouse sarcoma in vivo.

Acquired immunological tolerance of foreign cells is impaired by recombinant interleukin 2 or vitamin A acetate

The susceptibility of newborn mice to the inception of tolerance after exposure to antigen is associated with their deficiency in the production of endogenous interleukin 2 (IL-2). As further evidence of the complicity of IL-2 in the inception and maintenance of tolerance, it is shown here that a solid and long-lasting state of tolerance induced by the intravenous injection into newborn CBA mice of lymphoid cells from (CBA X C57BL/10ScSn)F1 hybrids can be brought to an end by the administration of exogenous IL-2 or by supplementing an otherwise normal diet with vitamin A acetate, the effect of which is to increase the proportion of the moiety of the T-cell population that produces IL-2. These results indicate that certain nonspecific stimuli can influence whether immunological tolerance is maintained.

Retinyl acetate-mediated augmentation of resistance to a transplantable 3-methylcholanthrene-induced fibrosarcoma. The dose response and time course

An otherwise conventional diet supplemented with retinyl acetate (vitamin A acetate; VAA) increased a specific antitumor resistance in vivo in mice, and this appeared to be due to the enhancement of immune functions rather than a direct antitumor activity. A range of VAA doses (up to 0.8 g VAA per kg of diet), fed for more than 6 months, did not induce any obvious signs or symptoms of hypervitaminosis A. The augmentation of resistance to transplanted tumor was linearly dependent on the dose of VAA. There was also a positive linear relationship between the resistance to transplanted tumor and the length of exposure to supplementary VAA relative to tumor inoculation time. The maximum resistance to transplanted tumor was observed in VAA-fed mice when the enrichment of the diet with VAA started three or more weeks before inoculation of tumor, whereas initiation of the VAA diet on the day of tumor administration or later had a negligible effect on the growth of tumor.

Arterial eicosanoid production following chronic exposure to a periarterial haematoma

Cisternal and lumbar cerebrospinal fluid obtained some days following a subarachnoid haemorrhage contains abnormally large quantities of various prostanoids; some may be partly the result of abnormal production by the cerebral arteries. The extra-arterial and intra-arterial production of 6 oxo PGF1 alpha (prostacyclin metabolite), PGE2, PGF2 alpha and TXB2 were measured in perfused rabbit common carotid arteries taken both from normal rabbits and from rabbits in which the arteries had been ensheathed by blood clot in vivo for 7 days using two techniques. Prostaglandin production by control arteries was highest during the first hour of perfusion but declined or increased marginally (PGE2) during the succeeding three hours. Arteries exposed to a periarterial haematoma for 7 days produced prostaglandins at a high rate throughout the 4 hours of study, and there was a progressive and marked increase in PGE2 production. The disproportionate increase in the cerebral vasoconstrictor PGE2 may reflect the inflammatory response which occurred in the adventitia of the vessels. Increased prostanoid production by cerebral arteries probably does contribute to the increased levels in CSF after subarachnoid haemorrhage.

A diet enriched in vitamin A acetate or in vivo administration of interleukin-2 can counteract a tolerogenic stimulus

A conventional diet enriched in retinyl acetate (vitamin A acetate; VAA) or in vivo administration of exogenous interleukin-2 (IL-2) can effectively annul the otherwise tolerogenic stimulus represented by (CBA X C57BL/10ScSn) F1 cells injected intraperitoneally into newborn CBA mice. On the basis of these data and results of others, we postulate that an antigenic stimulus associated with a relative lack of IL-2 (or generally the lack of a 'secondary stimulus') can be tolerogenic rather than immunogenic. However, the tolerogenicity of the antigenic stimulus can be substantially reduced or even converted to sensitization (R. P. Cleveland & H. N. Claman, J. Immun. 124, 474-480, 1980), when the antigenic signal is appropriately associated with a concomitant or additional stimulus possibly mediated through IL-2.

Subcellular distribution of heavy metals in liver and kidney of a narwhal whale (Monodon monoceros): an evaluation for the presence of metallothionein

The subcellular distribution of Zn, Cd, Cu and Hg in liver and kidney from a narwhal was determined by ultracentrifugation and gel filtration. Most of the total mercury in the liver and kidney was bound by the cellular pellet (88 and 73%, respectively). Of the total mercury, 7 and 11% was in the form of methylmercury in the liver and kidney, respectively. More than half (74%) of the total Zn and Cu in the kidney was in the cytosol and somewhat less than this was in the cytosol of the liver. Almost all of the cadmium in liver and kidney (88 and 92%, respectively) was in cytosol. Cytosolic fractions from liver and kidney were evaluated for the presence of metallothionein by analysing for Zn, Cd, Hg, Cu, Fe and--SH groups, by molecular weight estimation and by u.v. absorption spectra. Metallothionein was found in these organs in estimated concentrations similar to those present in terrestrial and other marine mammals.

Enhancement of specific antitumor immunity in mice fed a diet enriched in vitamin A acetate

Age-matched male CBA mice on a conventional or a vitamin A acetate (VAOAc)-rich diet were immunized with irradiated cloned 3-methylcholanthrene- or Harvey sarcoma virus-induced (McSa-1 or HT3-2.1) sarcoma cells and then challenged with viable corresponding or unrelated (non-crossreacting) syngeneic sarcoma cells. The survival of the specifically immunized mice on the VAOAc diet was significantly prolonged in comparison with all control groups of mice as assessed by using logrank tests. Moreover, the specific immunization markedly decreased the incidence of tumors after the McSa-1 (but not HT3-2.1) challenge in a group of mice on the VAOAc diet (5% tumor incidence) compared with the equivalent group on the control diet (50% tumor incidence). Neither the VAOAc diet nor in vivo immunization alone or combined influenced natural killer cell activity. Specific T-cell-mediated cytotoxicity after in vivo priming and in vitro boosting with sarcoma cells was increased in VAOAc-fed mice. However, the marginal increase in cytotoxicity does not in itself explain the strikingly increased resistance to tumor transplants in preimmunized mice on the VAOAc diet in comparison with preimmunized mice on the control diet. The results indicate that a diet enriched in VAOAc can modify the ability of the immune system of a mouse to respond effectively to tumor antigens and can influence whether a tumor grows or regresses.

Wound infection rates after gastric surgery in a Melbourne hospital

In four groups of 25 patients in whom perioperative prophylactic antibiotics were not used, the wound infection rates after partial gastrectomy were 40% in gastric cancer, 44% in chronic gastric ulcer, 24% in chronic duodenal ulcer and after trunkal vagotomy and pyloroplasty, the wound infection rate was 12%. In gastric cancer and chronic gastric ulcer, most wound infections were caused by enterobacteria, while in chronic duodenal ulcer almost all infections were caused by Staphylococcus aureus. Appropriate short-term perioperative prophylactic antibiotic use is likely to decrease wound sepsis rate in patients who have a gastric resection in the presence of gastric cancer or gastric ulcer.

T-cell-mediated enhancement of host-versus-graft reactivity in mice fed a diet enriched in vitamin A acetate

Retinol (vitamin A) and some of its derivatives have an important role in: (1) regulating growth, proliferation and differentiation of various tissues and (2) maintaining reproduction and visual function in man and higher animals. Vitamin A and retinoids are also known as potent immunoregulatory and antineoplastic agents. Their ability to increase reactivity to histoincompatible tissues is well documented but the mechanism of this action is unclear. Here we report that mice fed on an otherwise conventional diet supplemented with vitamin A acetate (VAA) respond to 10(5) semiallogeneic cells (a suboptimal dose) in a host-versus-graft (HvG) reaction, whereas mice on a conventional diet do not. It is possible to transfer this enhanced immune reactivity by injecting lymphoid cells from VAA-fed animals into those syngeneic mice maintained on the conventional diet. Using a positive selection technique, we demonstrate that the phenotype of the cell probably responsible for this phenomenon is Lyt 1+ 2-.

Differences in putative minor histocompatibility but not IgH genes can prevent T-cell priming and T--B co-operation in the response of mice to sheep erythrocytes

A positive association has been observed in Igh allotype "congenic' mice between skin graft rejection and a block to effective T--B co-operation in the development of both IgM and IgG responses to sheep erythrocytes. Mismatch of Igh alone is insufficient for such a block to become apparent since pairs of Igh-allotype congenic strains of mice which reciprocally accept skin grafts for at least 5 weeks, show successful positive co-operation (help) between T and B cells. The observed block is manifest both during the education (priming) of T cells in irradiated (first stage) recipients and during co-operation between primed T cells and unprimed B cells in second stage irradiated "syngeneic' recipients.

Anti-cancer action of retinoids

The anti-cancer action of retinyl acetate (Vitamin-A acetate, VAA), chosen as a representative retinoid substance, is attributed to its power to exercise immunopotentiation, though other possibilities are considered. The reasons for forming this opinion were: (1) chronic administration of VAA brought about enlargement of the thymus and peripheral lymph nodes; (2) the administration of VAA curtailed the life of skin allografts though (3) its action could be reversed by the concomitant administration of immunosuppressive agents.

An influence of diet on transplantation immunity

It was discovered by chance that mice raised under otherwise entirely conventional conditions of husbandry but fed upon autoclaved diet (diet A) had stronger cell-mediated immune reactions than those of mice raised under the same conditions but with an unmodified diet (diet B) : skin allografts were rejected more quickly, transplantation tolerance was more difficult to procure and fibrosarcomas induced by the injection of methylcholanthrene (MCA) arose more slowly and less often. Analysis showed that these findings could be explained at least in part by the discovery of Mertin & Hunt (1976, p. 928) that a partial deprivation of polyinsaturated fatty acids led to an intensification of cell-mediated immunity; on the other hand, experiments with dietary mixtures made it seem unlikely that this was the whole explanation and pointed towards some positive immunopotentiation by an ingredient of autoclaved diet. This, it was proposed, might be a compound of unknown composition resulting from the interaction of vitamin A with other dietary constituents. This interpretation was not supported by direct evidence but by confirming that retinol derivatives, especially retinyl acetate, could exercise an immunopotentiation of the kind and degree under investigation: retinyl acetate could counteract the immunosuppressive action of linoleic acid, though retinyl methyl ether was ineffective. Although retinyl derivatives may protect against MCA tumours by impeding its metabolic conversion to an oncogenic form, the effects of an autoclaved diet upon skin allograft survival, the induction of tolerance and the formation of tumours is probably mediated through an immunological mechanism.

Prolonged apnea of an oral surgery patient after administration of succinylcholine

To properly diagnose the presence of a genetic pseudocholinesterase variation, the family history is important. Furthermore, the DN and pseudocholinesterase tests are most useful, but if facilities for these are not available, one should be wary of patients with abnormal liver function tests. Certainly medical history, family medical history, laboratory evaluation, and knowledge of the disease processes should avoid unnecessary complications.

Reduction by linoleic acid of the severity of experimental allergic encephalomyelitis in the guinea pig

This paper reports the effects of supplementation of the diet with linoleic acid on the severity of experimental allergic encephalomyelitis (EAE) in guinea pigs. Clinical signs of disease (e.g. paresis, paraplegia, urinary incontinence), weight loss, frequency of perivascular lesions in the central nervous system and ability of isolated lymph node cells to respond to myelin basic protein in vitro were all reduced by linoleic acid supplementation. Linoleic acid was effective when fed at a dose of 0.5 ml/day from 7 to 21 days after sensitization of the animals with basic protein, i.e., before and during the time in which clinical signs normally appeared. The same daily dose fed from 7 days before to 7 days after sensitization, i.e., ceasing about 7 days before the normal time of appearance of clinical signs, produced no significant effect. Feeding linoleic acid to normal guinea pigs significantly altered the fatty acid composition of their serum and lymph nodes, but not of their brain. Of several possible explantations for the protective effect of lineolic acid in EAE, we considered action by this essential fatty acid on the immune system most likely.

Preclinical toxicological study of phosphonoacetic acid: determination in blood by selected ion monitoring

Confirmed observations of the inhibition of oncogenic viruses by phosphonoacetic acid led to preclinical trials in animal model systems. Circulating phosphonoacetic acid was detected in the blood of mouse, rabbit and monkey after oral or subcutaneous administration of the drug. Phosphonoacetic acid is quantified in blood, after removing proteins and lipids, as the trimethylsilylated derivative, by monitoring the intensity of the protonated molecular ion and also that of phosphonopropionic acid (internal standard) using chemical ionization mass spectrometry combined with gas chromatography. The detection limit is 20 ng ml-1 when 0.2 ml serum is analyzed. A dosage of 230 mg kg-1 day-1 by continuous infusion is proposed for therapeutic trials in monkeys. This dose is well tolerated and results in slowly increasing blood levels of phosphonoacetic acid which reach a maximum of approximately 50 microgram ml-1 in a four day infusion, and decrease to 2 microgram ml-1 24 h after termination.

Importance of the spleen for the immuno-inhibitory aciton of linoleic acid in mice

Certain immuno-inhibitory effects of a polyunsaturated fatty acid, linoleic acid (C18:2), no longer occur after splenectomy of young adult CBA mice. This observation suggest that the spleen is a major intermediary in the action of C18:2 on the lymphoreticular system. Pathways of this action remain to be elucidated. Possibilities include C18:2-stimulated suppressor cell generation in the spleen, or excess biosynthesis of immuno-inhibitory prostaglandins by splenic macrophages.

Hyperphenylalaninaemia and experimental allergic encephalomyelitis

Previous suggestions to the effect that a reduced proportion of long chain and unsaturated fatty acids in the CNS as induced by experimental hyperphenylalaninaemia in young rats may alter the biochemical reactivity and stability of the myelin have been examined using experimental allergic encephalomyelitis (EAE). Lewis rats treated chronically with phenylalanine during development showed a higher susceptibility to EAE and a more severe course of the disease than their medium-treated litter mates. The possible implications of this observation for EAE as an experimental model of multiple sclerosis (MS) is discussed briefly in the light of the decreased levels of unsaturated fatty acids found in the CNS of MS patients.

The significance of embryonic reexpression in cancer

Irradiated syngeneic mouse testicular cells and the first-trimester human fetal tissue cells protect mice partially against tumors induced by methylcholanthrene or against a syngeneic transplantable mouse tumor, Meth A, respectively. For future research it is suggested that experiments should have a therapeutic rather than a prophylactic design and that the induction of tolerance to fetal antigens could be a highly informative procedure.

Influence of polyunsaturated fatty acids on survival of skin allografts and tumor incidence in mice

Subcutaneous or oral administration of the polyunsaturated fatty acid linoleic acid prolongs survival of skin allografts in mice. Mice fed on a diet deficient in polyunsaturated fatty acids show a relative immunopotentiation, as indicated by accelerated skin allograft rejection and decreased incidence and rate of development of methylcholanthrene-induced tumors. These observations support the hypothesis that polyunsaturated fatty acids take part in immunoregulatory mechanisms.

The diagnosis of asbestosis

Lung biopsy in 16 patients with abnormal lung function and who had been exposed to asbestos revealed asbestosis in 4 with considerable radiological evidence of the disease, in of 4 with minimal radiological changes and in none of 8 with completely clear radiographs. Thus biopsy for the diagnosis of this condition should be avoided if the chest radiograph shows no evidence of it.