Showing papers on "In vivo published in 1979"

Activation of macrophages in vivo and in vitro. Correlation between hydrogen peroxide release and killing of Trypanosoma cruzi.

Abstract: As reported previously, mouse peritoneal macrophages could be activated to kill intracellular trypomastigotes of Trypanosoma cruzi, the agent of Chagas' disease, in either of two ways: by immunizing and boosting the mice (3), or by culturing resident or inflammatory macrophages in spleen cell factor(s) (SCF) in vitro (2). Macrophages activated in vivo became less trypanocidal with time in culture, and cells activated in vitro lost trypanocidal capacity when CSF was removed (2). In the present study, the ability of macrophages to release H2O2 in response to phorbol myristate acetate (PMA) could be induced in vivo and in vitro, and reversed in vitro, in a manner correlating closely with changes in trypanocidal activity. Macrophages could be activated in vitro with SCF in a time-dependent and dose-dependent fashion, so that they released as much H2O2 as macrophages activated in vivo. The sensitivity of epimastigotes and trypomastigotes to enzymatically generated H2O2 suggested that the generation of H2O2 by activated macrophages could be plausible explanation for their trypanocidal activity. Of the biochemical correlates of macrophage activation reported to date, increased ability to release H2O2 seems most closely allied to enhanced capacity to kill an intracellular pathogen.

Interactions of Hyperthermia and Chemotherapy in Animals

Abstract: In tissue culture, the cytotoxicity of a number of commonly used chemotherapeutic drugs is greatly enhanced at elevated temperatures. However, pharmacokinetics, drug concentrations, oxygen tension, and pH in tumors in animals can all vary widely from those in cell cultures. In addition, tissue culture studies do not give vital information on the effect of combinations of drugs and hyperthermia on normal tissues or metastases. Available studies of drugs and hyperthermia in animals are reviewed, and they yield clinically useful information. One study indicated that the activity of methotrexate was not enhanced by hyperthermia in vivo . Results for alkylating agents were not conclusive. Antitumor effects of 1,3-bis(2-chloroethyl)-1-nitrosourea, bleomycin, and cis -diamminedichloroplatinum, however, were significantly potentiated by local hyperthermia. 1,3-bis(2-chloroethyl)-1-nitrosourea effects were enhanced between 41 and 42°C, and thus, it is potentially of use in the setting of systemic hyperthermia. Bleomycin, however, was enhanced significantly only near 43°, suggesting that its clinical use is more appropriate with local hyperthermia. Adriamycin and S -(2-aminoethyl)isothiouronium dihydrobromide, although potentiated in vitro , were not potentiated in vivo in doses which were clinically tolerable. Discrepancies between the in vitro and in vivo findings are likely due, at least in part, to differences in drug concentration. The combination of local primary tumor hyperthermia and chemotherapy did not adversely affect the incidence or severity of spontaneous lung metastases in KHT tumor-bearing mice. Very few studies of the pharmacology of drugs in vivo in the presence of hyperthermia have been reported. Uptake of chemotherapeutic drugs may be enhanced in hyperthermic tissue. Further in vivo studies both of effectiveness and drug pharmacology for combined hyperthermia and chemotherapy are advisable to define optimum time-dose schedules for clinical trials.

Inhibition of the Action of Nonsuppressible Insulin-Like Activity on Isolated Rat Fat Cells by Binding to its Carrier Protein

Abstract: Nonsuppressible insulin-like activity extracted and purified from human serum (NSILA-S) mimics all insulin-like effects in vitro and, after injection, in vivo in the presence of excess insulin antibodies. However, there is no evidence that it exerts acute insulin-like effects in its native form in the circulation, where it is almost completely bound to a specific large molecular weight carrier protein. In this paper we show that partially purified NSILA-S-carrier protein, devoid of endogenous insulin-like activity, inhibits the stimulatory effect of NSILA-S, but not of insulin, on 3-0-methylglucose transport and on lipogenesis from [U-(14)C]glucose in isolated rat fat cells. Concomitantly, it prevents binding of (125)I-labeled NSILA-S to the insulin receptor and to the NSILA-S-binding site. The following explanation is, therefore, offered for the absence of acute insulin-like effects of native NSILA-S in vivo: In native serum NSILA-S occurs almost exclusively as NSILA-S-carrier complex. According to recent findings the passage of this complex through blood capillaries is restricted. The present results indicate that, in addition, it is metabolically inactive, or, at least, possesses reduced metabolic activity. The well-known phenomenon that whole serum, nevertheless, exerts pronounced nonsuppressible insulin-like effects on adipose tissue in vitro seems, therefore, to be mainly caused by the presence of a large molecular weight insulin-like protein not identical to the NSILA-S-carrier complex.

Rapid In Vivo Assay of Mouse Natural Killer Cell Activity

Abstract: A rapid elimination of tumor cells from some organs was detected in mice following iv injection of tumor cells labeld in vitro with [125I]5-iodo-2'-deoxyuridine. Recovery of radioactivity in different organs (spleen, liver, and lungs) was reduced in mice with high natural killer (NK) cell reactivity in their spleens, as measured in vitro by concomitant short-term 51Cr release assay. Considerable parallelism between in vitro and in vivo reactivities against two mouse lymphomas and a human myeloid cell line was found in mice of different strains and ages. Similarly, various immunophamacologic treatments had comparable effects on in vitro and in vivo reactivities. These findings are consistent with the hypothesis that rapid cytolysis of tumor cells occurred in vivo and that NK cells played a major role in their elimination.

Properties of coxsackievirus B3 variants which are amyocarditic or myocarditic for mice.

Abstract: Inoculation of adolescent CD-1 mice with one variant of coxsackievirus B3 (CVB3m) results in induction of readily observable myocardial lesions, whereas inoculation of siblings with a second variant (CVB3o) results in little or no myocarditis. These variants could not be distinquished from each other on the basis of replication properties in HeLa cells or cardiac tissues in vivo, sensitivity to human interferon in HeLa cells, induction of interferon in the mouse, generation of detectable levels of defective-interfering particles in HeLa cells or in cardiac tissue in vivo, stimulation of serum-neutralizing antibody titers, nor in their rate of clearance by the spleen. Infectivity of CVB3o was slightly more heat labile at 34 degrees C than CVB3m. Little if any replication of either CVB3o or CVB3m occurred in either adherent or nonadherent populations of normal murine lymphoid cells. Cardiac tissues from mice inoculated with CVB3m but not CVBo contain new antigens that can inhibit migration of sensitized lymphocytes from CVB3m-immunized mice in an in vitro cell-migration-inhibition assay. However, the CVB3o variant was shown to have the genetic capability of inducing myocarditis if the mice were treated with cyclophosphamide prior to virus inoculation. These results suggest, in agreement with our previously published work, that induction of myocarditis by CVB3 requires destruction of myocytes by virus and subsequent stimulation of cell-mediated responses to new antigens produced in the myocardium during virus replication.

Receptor-Binding Radiotracers: A Class of Potential Radiopharmaceuticals

Abstract: To date no radiopharmaceutical is routinely used to study changes in receptor concentration. Frequently changes in receptor concentration, or the appearance of receptors in tumors, indicates a specific pathologic state. With a receptor-binding radiotracer, in vivo studies of these changes will be possible. A reversible bimolecular model and in vitro tests were used to determine equilibrium constants and maximal target-to-blood ratios for new derivatives. Theoretical calculations showed that derivatives binding to the estrogen receptor, the beta adrenoceptor, or the cholinergic receptor are capable of achieving satisfactory target-to-blood ratios. Using in vitro tests, the apparent affinity constant was determined for five iodinated estrogen derivatives and five derivatives of beta blockers. Results of the in vitro study with derivatives of beta blockers. Results of the in vitro study with derivatives of beta blockers, and in vivo displacement studies using propranolol, indicated that the high heart-to-blood ratios (5 to 20) obtained with the new derivatives were not the result of a specific interaction with the receptor. In this instance factors other than receptor binding control the in vivo distribution. The in vitro assay using estrogen receptors showed that of the five derivatives, iodohexestrol and 17-alpha-iodoethynylestradiol bind to the receptor with the highest affinity.more » In vivo studies confirmed these results; iodohexestrol gave a uterus-to-blood ratio of 10 in immature rats when plasma-protein binding was blocked. With a tritiated muscarinic cholinergic blocking agent, heart-to-blood ratios near the theoretical maximum were obtained. This compound most closely follows the mechanism described by the model. Use of the theoretical model in conjunction with in vitro assays can greatly aid in the design of this new class of receptor-binding radiopharmaceuticals.« less

Radiosensitization of hypoxic tumor cells by cis- and trans-dichlorodiammineplatinum (II)☆

Abstract: The effects of the chemotherapeutic agent cis -dichlorodiammineplatinum (II) or its trans isomer on tumor cell lethality were evaluated following administration of the drugs, alone, or in combination with x-irradiation. The tumor latency method was employed to assay tumor cell survival under in vivo growth conditions following treatment in vivo . Radiosensitization of hypoxic tumor cells was demonstrated by combinations of either complex with high doses of radiation. The results extend an effect observed in bacterial systems and cultured mammalian cells to include tumor cells treated in situ . However, therapeutic potentiation during more clinically relevant treatment protocols in air-breathing mice is probably the result of the platinum complexes inhibiting recovery processes following irradiation.

The effect of prostacyclin (PGT2) on platelet behaviour. Thrombus formation in vivo and bleeding time.

Abstract: Prostacyclin (PGI2) infused intravenously into anaesthetized rabbits inhibited electrically-induced thrombus formation in the carotid artery, increased bleeding time and inhibited ex vivo platelet aggregation induced by ADP or arachidonic acid. The increase in bleeding time and the inhibition of ex vivo platelet aggregation lasted for as long as the infusion of PGI2 was maintained but rapidly disappeared after infusion was stopped. Prostacyclin is a more potent inhibitor of platelet function, in vivo than prostaglandin E1 (PGE1) or prostaglandin D2 (PGD2). The effects of prostacyclin on all parameters studied except blood pressure were potentiated by the concomitant administration of theophylline, a phosphodiesterase inhibitor.

Electrophoretically pure mouse interferon exerts multiple biologic effects.

Abstract: Electrophoretically pure mouse interferon was examined for a number of biologic effects previously ascribed to crude or partially purified interferon preparations. These effects include: inhibition of the growth of a transplantable tumor in mice; inhibition of cell multiplication of mouse tumor cells in vitro; enhancement of the expression of histocompatibility antigens on mouse tumor cells in vitro; inhibition of antibody formation in vitro; inhibition of sensitization to sheep erythrocytes and the expression of delayed type hypersensitivity in mice; enhancement of natural killer cell activity in vivo and in vitro; enhancement of cell sensitivity to the toxicity of poly(I)-poly(C); and enhanced production ("priming") of interferon production in vitro. Our results establish that the molecules responsible for the antiviral action of interferon are also responsible for these varied biologic effects.

Platinate toxicity: past, present, and prospects.

Abstract: Using traditional toxicologic methods, four species were studied for their qualitative and quantitative predictiveness of the toxic effects of cis-dichlorodiammineplatinum(II) in man Of the four species studied, mouse, monkey, rat, and dog, the latter two gave the best overall results Using an in vivo rat model, it was found that except for chloroplatinic acid, eight of the tested analogs were less nephrotoxic than the parent drug, cis-dichlorodiammineplatinum(II) The in vitro renal toxicity screen using flounder tubules showed that of the 26 compounds studied, about half were less toxic than the parent compound This in vitro mini-tox system can be performed about 30 times faster and at one fiftieth the cost of the in vivo model The in vitro studies also provided evidence that the biochemical site of toxicity of platihates is on ATPases The latter studies suggested a basis for unifying the mechanistic interpretation of the toxic actions on such disparate target organs as the kidney, nerve, stomach, and inner ear

A Methodological Approach to the Prediction of Anticancer Drug Effect in Humans

Abstract: Tumor cells from animals and humans were treated with drugs under tissue culture conditions. Tumor cells from the sensitive L1210 model were studied first. A dose-response curve was derived between drug exposure and subsequent cytotoxicity in L1210. The concentration of drug and duration of exposure were factors critical to the subsequent development of in vitro cytotoxicity. The in vitro dosage which effected 50% leukemic cell death in L1210 cells correlated with reported in vivo drug levels. Other tumor models and human neoplastic cells were studied at this dosage level. A good correlation was noted in these studies between the in vivo responsiveness and the in vitro chemotherapy results in both animals and humans. It was suggested by these results that it may be possible to predict cancericidal drug activity for individual neoplasms by assaying the tumor cells in vitro for drug sensitivity.

Procollagen synthesis and processing in periodontal ligament in vivo and in vitro. A comparative study using slab-gel fluorography.

Abstract: A combination of dodecylsulphate/polyacrylamide gel electrophoresis and fluorography has been used to quantify the synthesis of type I and type III collagens by periodontal ligament in situ and periodontal-ligament fibroblasts in vitro. The separation of 14C-labelled collagen alpha chains was achieved by introducing an interrupted reduction step, and the total radioactivity in the alpha-chain bands related to the fluorographic response by a series of standard curves. From these curves an accurate assessment of the relative amounts of type I and III collagen synthesized could be made. The same system also allowed the synthesis and processing of the respective procollagens to be analyzed. For the study in vivo, 200-g male rats were injected with 2 mCi [14C]glycine and killed 0.5-6 h later. Periodontal ligament was dissected from the mandibular molars and the newly-synthesized collagens extracted with 0.45 M sodium chloride. In the study in vitro, confluent monkey periodontal-ligament fibroblasts were cultured in the presence of [14C]proline and [14C]glycine. Analysis of labelled collagens showed a rapid conversion of type I procollagen to collagen but type III collagen was recovered as a procollagen intermediate both in vitro and in vivo. Analysis of duplicate samples after pepsin digestion showed type III collagen synthesis to comprise 15% of the total collagen synthesized in vivo and 20% in early subcultures in vitro. However, the proportion of type III synthesized by the fibroblasts decreased on subculturing. The data demonstrate that fibroblasts in vitro retain the basic characteristics of collagen synthesis and procollagen processing found in vivo, but the overall phenotypic expression of the cells is not stable in culture.

Cyclosporin A: in vivo and in vitro suppression of rat T-lymphocyte function.

Abstract: The immunosuppressive effect of cyclosporin A (CS-A) was investigated in RIC-Sprague-Dawley rats. In vivo, CS-A totally abolished the formation of antibodies to the hapten dinitrophenyl (DNP) in rats immunized with DNP-keyhole limpet haemocyanin. In vitro, the effect of CS-A was investigated in spleen cell cultures stimulated by concanavalin A, phytohaemagglutinin or lipopolysaccharide. The suppression due to CS-A was more pronounced in cultures set up with cells from rats fed the drug than in spleen cell cultures from control animals supplemented with serum containing CS-A. Purified by filtration through Degalan-rat Ig-anti IgG columns, T lymphocytes from CS-A treated rats were no longer suppressed by CS-A serum in contrast to purified T cells obtained from control rats. Thus, CS-A seems to interfere with the mitogenic triggering of a subpopulation of T lymphocytes resulting in a functional clonal deletion.