Showing papers on "In vivo published in 1971"
TL;DR: It was concluded that sugars that migrate from the chloroplast to the cytoplasm were the prime source of energy and that the oxidation of glyceraldehyde 3-phosphate was ultimately the in vivo source of NADH for nitrate reduction.
Abstract: An in vivo assay of nitrate reductase activity was developed by vacuum infiltration of leaf discs or sections with a solution of 02 m KNO 3 (with or without phosphate buffer, pH 75) and incubation of the infiltrated tissue and medium under essentially anaerobic conditions in the dark Nitrite production, for computing enzyme activity, was determined on aliquots of the incubation media, removed at intervals By adding, separately, various metabolites of the glycolytic, pentose phosphate, and citric acid pathways to the infiltrating media, it was possible to use the in vivo assay to determine the prime source of reduced nicotinamide adenine dinucleotide (NADH) required by the cytoplasmically located NADH-specific nitrate reductase It was concluded that sugars that migrate from the chloroplast to the cytoplasm were the prime source of energy and that the oxidation of glyceraldehyde 3-phosphate was ultimately the in vivo source of NADH for nitrate reduction This conclusion was supported by experiments that included: inhibition studies with iodoacetate; in vitro studies that established the presence and functionality of the requisite enzymes; and studies showing the effect of light (photosynthate) and exogenous carbohydrate on loss of endogenous nitrate from plant tissue The level of nitrate reductase activity obtained with the in vitro assay is higher (25- to 20-fold) than with the in vivo assay for most plant species The work done to date would indicate that the in vivo assays are proportional to the in vitro assays with respect to ranking genotypes for nitrate-reducing potential of a given species The in vivo assay is especially useful in studying nitrate assimilation in species like giant ragweed from which only traces of active nitrate reductase can be extracted
365 citations
TL;DR: Incorporation of 3H from 3H2O was used to measure the rate of fatty acid synthesis in rat liver as discussed by the authors, and showed that 3H-citrate strongly inhibits fat acid synthesis.
245 citations
TL;DR: Although this factor generated in an in vitro system, it has been shown to possess in vivo as well as in vitro activity, it is therefore possible that this factor may be of biological significance in situations where eosinophils are participants in inflammatory or immunologic reactions.
Abstract: When cultured in the presence of specific antigen, lymphocytes from delayed-hypersensitive guinea pigs release a number of biologically active substances into the culture medium. Such active supernatants can react with immune complexes in vitro to generate a factor which is chemotactic for eosinophils. The factor involved is unique, since previously described chemotactic factors for other cell types require for their generation either immune complexes or substances released into lymphocyte culture, but not both. In the case of the eosinophil chemotactic factor, the interaction between the substance elaborated by the lymphocytes and the immune complexes appears to be specific in that the immune complexes must contain the same antigen as that used to activate the lymphocyte cultures. Although this factor was generated in an in vitro system, it has been shown to possess in vivo as well as in vitro activity. It is therefore possible that this factor may be of biological significance in situations where eosinophils are participants in inflammatory or immunologic reactions.
159 citations
Journal Article•
139 citations
TL;DR: Normal human sera were able to stimulate granulocyte and macrophage colony formation in vitro by mouse bone marrow cells, but only following removal of inhibitory material either by dialysis or by heat‐ or ether‐treatment.
Abstract: Summary. Normal human sera were able to stimulate granulocyte and macrophage colony formation in vitro by mouse bone marrow cells, but only following removal of inhibitory material either by dialysis or by heat- or ether-treatment. Inhibitors were shown to be present in all normal human sera tested, to exhibit partial species specificity, to be multiple and to be probably lipoprotein in nature. The in vivo function of these inhibitors is unknown but they may modulate the action of the colony stimulating factor (CSF) in stimulating granulopoiesis and macrophage formation.
129 citations
TL;DR: The polymyxin antibiotics are inactivated in vitro by tissues because they are bound to phospholipids of cell membranes, and a method that liberates bound drug in an active form from tissues permitted study of distribution and persistence in vivo.
Abstract: The polymyxin antibiotics are inactivated in vitro by tissues because they are bound to phospholipids of cell membranes. A method that liberates bound drug in an active form from tissues permitted study of distribution and persistence in vivo. Studies using single injections in the rabbit showed that bound drug persists in liver, kidney, brain, heart, muscle, and lung for as long as 72 hr. Accumulation in tissue but not in serum was noted on repeated injection, with persistence for at least five days after seven daily injections. Free polymyxin B was detectable in liver, kidney, muscle, and brain and persisted for many days in muscle and brain. Free colistimethate was detectable in all tissues other than brain and persisted for many days in liver, kidney, and muscle. Colistimethate appears to be incompletely converted in vivo to the parent compound, colistin. These observations may account for differences in toxicity and chemotherapeutic efficacy of polymyxin B and colistimethate.
108 citations
TL;DR: It was, therefore, somewhat surprising to find that the enhancing effect of the carrier-primed cells, once they had been generated, is not inhibited by x-irradiation.
Abstract: The in vitro primary response of mouse spleen cell suspensions to 2,4,6-trinitrophenyl(Tnp)-erythrocytes has been studied. The number of anti-Tnp plaque-forming cells that arise after antigenic stimulation in vitro is greatly enhanced by prior immunization in vivo with the carrier erythrocyte. The enhancement is antigen specific. The priming for an enhanced response can be elicited with very low antigen doses and is often apparent 24 hr after immunization. It is marked from day 3 to day 14. Spleen cells from carrier-primed mice will enhance the anti-Tnp response of normal cells when mixed cultures of the two cell populations are challenged with Tnp-erythrocytes in vitro. The carrier-primed cells mediating this enhancing effect are thymus derived.
The development of the thymus-derived, carrier-specific cell population has been generally assumed to involve the antigenic stimulation of cell proliferation. It was, therefore, somewhat surprising to find that the enhancing effect of the carrier-primed cells, once they had been generated, is not inhibited by x-irradiation.
94 citations
TL;DR: Incorporation of amino acid into protein was reduced in both brain and liver ribosomes 1.5–3 hours after a single administration of ethanol, suggesting ribosomal protein synthesis is rather insensitive to the in vitro addition ofanol, as compared with the in vivo administration.
86 citations
TL;DR: It is observed that 30 min after injection of glucagon and H, 32P0,, phosphorylation of ribosomal proteins was strongly increased, and autoradiography after electrophoresis of these proteins showed that phosphorylated of one ofThese proteins was stimulated 2 or 3 fold after injectionof glucagon.
79 citations
78 citations
TL;DR: The synthesis of vaccinia virus double-stranded ribonucleic acid (RNA) in infected HeLa cells was sensitive to actinomycin D, suggesting that a deoxyribon nucleic acid dependent reaction is involved.
Abstract: The synthesis of vaccinia virus double-stranded ribonucleic acid (RNA) in infected HeLa cells was sensitive to actinomycin D, suggesting that a deoxyribonucleic acid dependent reaction is involved. Some double-stranded RNA was made in the presence of cytosine arabinoside in infected cells. Double-stranded and complementary RNA were synthesized in vitro by using vaccinia cores. These two observations indicate that some of the double-stranded RNA is read from “early” genes. The double-stranded RNA synthesized in vitro had the same properties as that made in vivo. At least 70% of the double-stranded RNA made in vivo was in ribonuclease-resistant form prior to sodium dodecyl sulfate-phenol extraction. In addition, there was a complementary RNA in infected cells which could be converted to double-stranded RNA by annealing.
TL;DR: The influence of various drugs at plasma concentrations encountered clinically on the extent of binding of digitoxin to albumin was investigated and appeared to indicate that relatively high concentrations of phenylbutazone can displace the glycoside from its binding site on the protein.
Abstract: Many potent and effective drugs are available, and to use them properly requires a thorough knowledge of their own actions as well as interactions with other drugs. It has been recognized that one drug may profoundly influence the pharmacologic response to another by competing for binding sites on various proteins or altering rates of metabolism or excretion.' In this regard, relatively little has been reported concerning the cardiac glycosides. Digitoxin (FIGURE 1) is a cardenolide that consists of a steroid nucleus with a five-membered unsaturated lactone ring at carbon atom 17 of ring D and three molecules of the hexose, digitoxose, at carbon atom 3 of ring A, joined by an ether linkage. In man this drug is avidly bound to albumin and metabolized exten~ively.'.~ Only a small part of the administered dose is excreted in the urine as intact drug. Digitoxin, as is well known, has a long duration of action in man and a plasma half-life of approximately six days. The binding of tritiated digitoxin to human albumin in uitro was studied by means of the ultrafiitration technique of Rehberg.4 Such binding of the glycoside was measured over a range of concentrations extending from 0.5 to 3.9 X W6M/1. The final concentration of albumin in these studies was 1.45 X lO-'M/l unless otherwise stated. The formulation of Klotz' was used to estimate the number of binding sites for digitoxin on albumin, to determine the affinity of digitoxin for the protein, and to characterize the influence of other drugs on the binding of digitoxin. A linear relation was demonstrated between the reciprocals of the concentration of unbound digitoxin and the moles of digitoxin bound per mole of albumin over the range concentrations of digitoxin studied (FIGURE 2). The drug is avidly bound to a single site on human albumin. In the presence of phenylbutazone, less digitoxin was bound to albumin (FIGURE 2). The displacement of the binding plot to the left and the common ordinate intercept indicate that relatively high concentrations of phenylbutazone can displace the glycoside from its binding site on the protein. The influence of chlorophenoxyisobutyric acid (CPIB) on the binding of digitoxin to human albumin is presented in FIGURE 3. At a concentration of 10-3M, CPIB is more potent than phenylbutazone as a displacer of digitoxin. The influence of various drugs at plasma concentrations encountered clinically on the extent of binding of digitoxin to albumin was also investigated (TABLE 1). All drugs selected for this study are known to bind to albumin and are frequently administered concurrently with digitoxin. When digitoxin was present at a concentration commonly encountered under clinical conditions (25 mpg/ml), 93 percent of the drug was bound to albumin. The extent of binding of digitoxin to this protein was not influenced by such drugs as phenylbutazone, sulfadimethoxine, and phenobarbital; but tolbutamide and CPIB decreased the
TL;DR: The demonstration that a radiation-resistant cell is required in vivo and that this cell has properties identical to the radiation- resistant cell required in vitro indicates that thiscell (the A cell) is directly involved in the initiation of an immune response to erythrocyte antigens.
Abstract: Experiments have been done to establish whether the radiation-resistant or A cell has a specific function in the initiation of an immune response in mice to sheep erythrocytes (SRBC). All previous demonstrations using accessory (A) cells have involved in vitro assays and are possibly explainable as tissue culture artifacts. If A cells are essential, it should be possible to demonstrate their requirement in vivo. Therefore we first established such conditions. Two methods were found for creating an A-cell deficiency in vivo: (a) A cells disappear gradually from the spleens of irradiated mice, presumably by migration since A-cell function was shown not to be decreased by irradiation. If 3 days elapse between irradiation and transplantation of mixtures of bone marrow and thymus cells (which provide B and T but few A cells), the usual synergistic response does not occur. Addition of large numbers of freshly irradiated spleen cells to the mixture of bone marrow and thymus completely restores the immune response. (b) Injection of 1010 horse erythrocytes into mice suppresses A-cell activity in these mice 24 hr later; a much reduced response to SRBC is obtained when they are given at this time. The response can be partially restored if irradiated spleen cells are given with the SRBC. This observation formed the basis for a quantitative in vivo assay for A cells in which the magnitude of restoration by various suspensions of irradiated cells was used to estimate the A-cell activity of that suspension. A quantitative in vitro assay for A cells was also developed. It was essential for this assay that the total cell number, B-cell number, and T-cell number be kept constant and that only the number of A cells be allowed to vary. Only under these conditions was the response a linear function of the number of A cells added. If the in vivo and in vitro assays are detecting the same class of radiation-resistant cells, the physical properties of the cells active in each assay should be identical. Spleen cells were separated on the basis of both density and sedimentation velocity. Fractions from both separation methods were tested for their content of A cells using both the in vivo and in vitro assays. The density and sedimentation profiles of A cells were similar in both assays. The demonstration that a radiation-resistant cell is required in vivo and that this cell has properties identical to the radiation-resistant cell required in vitro indicates that this cell (the A cell) is directly involved in the initiation of an immune response to erythrocyte antigens.
TL;DR: In all experiments the specific activity of prolactin in the medium became significantly greater than that in the tissue, and was as high as 2.7 times that of the tissue in some cases.
Abstract: Adenohypophyses (AP) of female rats were exposed to 3H-leucine either in vivo or in vitro, then incubated in vitro. The prolactin (PI) in the tissues and incubation medium was separated and quantified by disc electrophoresis (DE) and densitometry. The PI bands were cut from the gel columns and counted by liquid scintillation procedures. In all experiments the specific activity of prolactin (cpm/μg) in the medium became significantly greater than that in the tissue, and was as high as 2.7 times that of the tissue in some cases. This indicated that prolactin was secreted in vitro from more than one pool, with the newly synthesized (labeled) hormone being rapidly released. One rapid turnover pool was indicated by an increase of as much as 100% in medium PI specific activity between 40 and 70 minutes of incubation of AP labeled in vivo one hour before incubation. This early increase did not occur with AP labeled in vivo 4 hours. Another less rapid turnover pool was suggested by a greater discrepancy between m...
TL;DR: Observations at three concentrations supported the hypothesis that transfer of unchanged drug occurred by passive diffusion and converted some of the chlorpromazine to products, which together with unchanged drug, were partly retained in the intestinal wall and partly transferred to the serosal side of the tissue.
Abstract: 1. Concentrations of total radioactivity in plasma of rats given intravenous and oral 35S-chlorpromazine, were similar. Concentrations of unchanged drug, however, were lower after oral doses.
2. Chlorpromazine circulated in solution through isolated loops of rat intestine was rapidly absorbed by the tissue. Measurements of glucose transport and histological examination indicated that the tissue was intact. In these in vitro experiments some of the chlorpromazine was converted to products, which together with unchanged drug, were partly retained in the intestinal wall and partly transferred to the serosal side of the tissue. Observations at three concentrations supported the hypothesis that transfer of unchanged drug occurred by passive diffusion.
3. Conversion of chlorpromazine to metabolites in the intestine in vivo, would account for the differences in concentrations of chlorpromazine and total radio-activity in plasma after oral doses.
TL;DR: Observations indicate that pulmonary conversion in vivo and plasma conversion in vitro occur via a dipepridylcarboxypeptidase and that a D-amino acid at the C-terminus prevents conversion.
Abstract: The conversion mechanism was studied in vivo in the pulmonary circulation of the intact anesthetized dog and in vitro in plasma by using L-Leu-angiotensin I, D-Leu-angiotensin I, and des-Leu-angiotensin I which had been synthesized by the solid-phase technique. The results obtained indicate that pulmonary conversion in vivo and plasma conversion in vitro occur via a dipeptidylcarboxypeptidase and that a D-amino acid at the C-terminus prevents conversion.
TL;DR: Whole blood cultures from humans and from the New World primate, Saguinus fuscicollis, were irradiated with various doses of 250 kV X-rays, and the resulting centric ring plus dicentric aberration yields were fitted to the three models, Y = a+bD, Y + bD+cD2, and Y + cD2 by least squares regression.
Abstract: Whole blood cultures from humans and from the New World primate, Saguinus fuscicollis, were irradiated with various doses of 250 kV X-rays. The resulting centric ring plus dicentric aberration yields were fitted to the three models, Y = a+bD, Y = a+bD+cD2, and Y = a+cD2, by least squares regression. In both instances the best fit was to the model Y = a+bD+cD2, with coefficients of the one- and two-track components for human and marmoset being: b = (0.78 ± 0.09)·10−3, c = (5.92 ± 0.31)·10−6, and b = (1.11 ± 0.36)·−3, c = (7.7 ± 1.7)·10−6, respectively. Whole-body irradiation of several marmosets was done with 60Co γ-rays at a dose rate of 3.7 R/min. Blood samples were drawn immediately and 24 h after the irradiation, and the aberration yields in the circulating leukocytes were measured. The aberration yields at the two sampling times were identical. Concurrent with these studies, freshly drawn whole blood was irradiated in the same manner for the purpose of in vivo to in vitro radiosensitivity comparison. In this instance the in vitro irradiation produced aberration yields identical to those from in vivo irradiation.
01 Jan 1971
TL;DR: A technique for a total hepatectomy in the rat has been developed, allowing estimations of extrahepatic and hepatic drug metabolism in vivo, and the course of IPNO metabolism, compartmental distribution and biliary excretion of the drug and its metabolites was studied in rat liver perfusion experiments.
Abstract: The metabolism of chlorpromazine (CPZ), imipramine (IP), and imipramine-N-oxide (IPNO) was studied in microsomal preparations of various rat tissues in vitro and in the isolated perfused liver. A technique for a total hepatectomy in the rat has been developed, allowing estimations of extrahepatic and hepatic drug metabolism in vivo. CPZ is converted to its sulfoxide and other metabolites in the liver and, to a minor degree, in many extrahepatic organs except brain and skin. Whole blood of several species shows a remarkable sulfoxidizing activity which can be traced to the hemoglobin and is likely to represent a heme catalysis. IP is metabolized in the liver in vitro and, to a very minor extent, in lung and kidney. Blood, brain and many other extrahepatic tissues do not metabolize this drug in vitro. However, gastro-intestinal contents of rats and humans demethylate IP to Desmethylimipramine (DMI). This is likely to be the reason for a hepatic/ extrahepatic metabolism ratio of 53/47 measured in sham operated and totally hepatectomized rats. The occurrence of IPNO metabolism in extrahepatic tissues in vitro was confirmed in vivo with hepatectomized rats. The hepatic/extrahepatic ratio is 10/90. The course of IPNO metabolism, compartmental distribution and biliary excretion of the drug and its metabolites was studied in rat liver perfusion experiments. Immediate partial conversion of IPNO to IP and DMI by hemoglobin was confirmed by perfusion experiments without the liver, and liver perfusions with hemoglobin-free perfusates.
TL;DR: The synthesis of nitrosopiperidine in rats from nitrite and piperidine is reported, both in the stomach and in the small intestine in vivo, and in vitro at near neutral pH values in the presence of enteric bacteria.
Abstract: SINCE the first report of hepatic cancer in rats induced by nitrosodimethylamine1, many nitrosamines have been shown to be carcinogenic in a wide range of organs of a wide variety of species1–4. Following the suggestion that dietary nitrite and secondary amines might interact in the human stomach to form nitrosamines5, such synthesis has been demonstrated in vitro with animal and human gastric juice6,7, and in vivo in laboratory animals7 and man8; nitrosamine synthesis was pH-dependent7–10. Nitrosamines can also be synthesized in vitro at near neutral pH values in the presence of enteric bacteria11; yields of nitrosamines are also determined by the basicity of the secondary amine. Presumptive evidence for in vivo synthesis of nitrosamines has been demonstrated by the induction of tumours in rats following chronic feeding of nitrite and secondary amines11. We report here the synthesis of nitrosopiperidine in rats from nitrite and piperidine in gastric contents in vitro, and in the stomach and in the small intestine in vivo.
TL;DR: To evaluate the effects of therapy on the vascular complications of adult diabetes, the University Group Diabetes Program carried out a prospective double-blind study in 12 centers across the country.
Abstract: To evaluate the effects of therapy on the vascular complications of adult diabetes, the University Group Diabetes Program (UGDP) carried out a prospective double-blind study in 12 centers ...
TL;DR: Supernatant fluids of specifically stimulated lymphocyte cultures were purified andractions containing migration inhibition factor when injected intra-dermally into strain-2 guinea pigs produced a reaction similar to delayed cutaneous hypersensitivity.
Abstract: Supernatant fluids of specifically stimulated lymphocyte cultures were purified. Fractions containing migration inhibition factor when injected intra-dermally into strain-2 guinea pigs produced a reaction similar in appearance to delayed cutaneous hypersensitivity. There was an accumulation of mononuclear cells at the injection sites and the growth of syngeneic tumor grafts at the sites was suppressed.
TL;DR: In vivo and in vitro, cycloheximide in a dosage that inhibits total liver synthesis by over 90% has little or no effect on labeling of nascent protein on polysomes by radioactive leucine but a marked effect on the labeling of sap protein.
TL;DR: Evidence supports the concept that the antigen-antibody complexes have a direct immunosuppressive effect on the lymphocyte, as demonstrated in the case of lymphocyte-tumor cell assay system.
Abstract: The ability of antisera to suppress immune responses either in vivo or in vitro is well known. A variety of lymphocyte-target cell systems have been employed to demonstrate inhibition of cell-mediated immunity by antisera in vitro, and skin, tumor, and kidney graft survival have been prolonged by passively administered antiserum in vivo. An in vitro lymphocyte-tumor cell assay system was developed for the purpose of studying the effects of enhancing antisera (in vivo) on lymphocyte-mediated cytotoxicity in vitro. The characteristics of this system with respect to route of immunization, time of harvest of immune cells, lymphocyte:tumor cell ratio, and effect of nonimmune or nonspecifically immune lymphoid cells are presented. Sera capable of enhancement in vivo were tested in this system and shown to inhibit cell-mediated immunity in vitro. Further, in both instances the immunosuppressive effect is mediated by antigen-antibody complexes and not by free antibody alone.
Experiments were also carried out to determine the site of action of these suppressive antigen-antibody complexes. Presensitized lymphocytes were exposed to antigen-antibody complexes, washed, and then allowed to interact with fresh tumor cells (not antibody treated). Lymphocytes treated in this manner are incapable of exhibiting cell-mediated immunity in vitro. This evidence supports the concept that the antigen-antibody complexes have a direct immunosuppressive effect on the lymphocyte.
TL;DR: In this article, the authors argue against a "solvent effect" in the loss of G6P-ase in the whole animal, arguing against the theory that the destruction of enzyme activity by CCl4 is due to the action of lipid peroxides or to the deleterious action of peroxidizing free radicals.
TL;DR: The dose–response curves for the production of chromosome aberrations in peripheral blood lymphocytes have been determined for radiation exposure both in vitro and in vivo, with essentially the same results after irradiation in vivo and in vitro.
Abstract: SummaryThe dose–response curves for the production of chromosome aberrations in peripheral blood lymphocytes have been determined for radiation exposure both in vitro and in vivo. The in vitro response with 2 MeV x-rays follows approximately dose-squared kinetics over a range of 0–300 R. At low doses peripheral blood from an individual gives essentially the same results after irradiation in vivo and in vitro, but differences exist between individuals, though the response of blood cells from patients with cancer did not differ in this respect from controls. Extrapolation of in vivo data to doses higher than 50 R on the basis of the available in vitro data cannot yet be done with any certainty. More information is required on the shape of the in vivo dose–response curve, on the effect of the time after exposure at which the sample is taken and other possible factors that may cause variations.
TL;DR: In vitro, but not in vivo, some gram-positive and gram-negative bacteria are inhibited by low concentrations of clotrimazole, and Pretreatment with the agent may decrease its efficacy because of drug inactivation.
Abstract: Clotrimazole has a broad spectrum of activity against yeast and filamentous fungi in vitro and also in vivo when given orally or parenterally to experimentally infected mice and when administered orally or topically to infected guinea pigs. In vitro a distinct inoculum effect has been observed with a number of strains of Candida and Torulopsis; minimal inhibitory concentrations have tended to increase with increased incubation time. With prolonged incubation times, resistance can be developed to clotrimazole in vitro, but this resistance is readily reversible upon passage in drug-free broth. The degree of in vivo activity of clotrimazole against Candida depends on the severity of infection used. Orally it appears to be more effective when administered by gavage than when given mixed in the diet. Pretreatment with the agent may decrease its efficacy because of drug inactivation. Against dermatophytes, clotrimazole has a degree of activity similar to griseofulvin when given orally, but it is less active than tolnaftate topically in cutaneous infection of Trichophyton mentagrophytes in guinea pigs. In vitro, but not in vivo, some gram-positive and gram-negative bacteria are inhibited by low concentrations of clotrimazole.
TL;DR: Two mitochondrial enzymes, succinic dehydrogenase and monoamine oxidase were found to be S peak enzymes in the synchronized L5178Y cells, and in vitro the synthesis by the isolated mitochondria of protein occurred only in G1.
TL;DR: The results seem to suggest that corticosteroids inhibit collagen biosynthesis by inhibiting the formation of polypeptide precursors of collagen.