Showing papers on "In vivo published in 1984"
TL;DR: [His1,Lys6] GHRP may be a valuable peptide for investigating the function of the pituitary somatotrophs and has the potential for increasing BW gain of a variety of normal animals by inducing GH release via a direct pituitsary site of action.
Abstract: His-DTrp-Ala-Trp-DPhe-LysNH2, [His1,Lys6] GHRP, is a new synthetic hexapeptide which specifically elicits a dosage-related release of GH in vitro and in vivo without a concomitant release of LH, FSH, TSH, or PRL and, in limited in vivo studies, insulin or glucagon. Our results indicate that this small peptide has the attributes of a hypophysiotropic hormone. In vitro the minimum and maximum active dosages ranged from 1-10 ng/ml in the pituitary incubate assay. It was active in rats, monkeys, lambs, calves, and under special experimental conditions chicks, indicating its lack of species dependency. It was active when administered iv, sc, or ip to rats. After iv injection, GH levels rose within 2 min, peaked at +10-20 min, and by 2 h usually had returned to normal. It was not possible to directly compare the potencies of [His1,Lys6]GHRP, and the GH-releasing factors GHRF-44 and GHRF-40 after a single sc injection in rats because the time course of the GH response of these peptides was different. The GH response of [His1,Lys6]GHRP was longer in duration than either of these larger peptides. Both SRIF-14 and SRIF-28 inhibited the GH response of the hexapeptide; however, SRIF-28 was about four times more active than SRIF-14 in vitro and 7.5 times more active in vivo. When this small peptide was administered sc once or twice daily to immature rats for 9 or 25 days, the BW gain increased above the control. At the end of the weight gain studies the pituitary remained fully responsive to the peptide. Thus, [His1,Lys6] GHRP may be a valuable peptide for investigating the function of the pituitary somatotrophs and, in addition, it has the potential for increasing BW gain of a variety of normal animals by inducing GH release via a direct pituitary site of action.
674 citations
TL;DR: The recombinant lymphokine supports the growth of murine and human interleukin-2 dependent cell lines, enhances the generation of cytolytic cells in vitro and in vivo after alloimmunization, and generates lymphokin activated killer cells from murineand human lymphocytes.
Abstract: The gene for interleukin-2 was isolated from the Jurkat cell line and from normal peripheral blood lymphocytes and, when inserted in Escherichia coli, was expressed at high concentrations. This interleukin-2 was purified to apparent homogeneity and tested for biological activity in a variety of assays in vitro and in vivo. The recombinant lymphokine supports the growth of murine and human interleukin-2 dependent cell lines, enhances the generation of murine and human cytolytic cells in vitro, and generates lymphokine activated killer cells from murine and human lymphocytes. It has a serum half-life of 2 to 3 minutes in the mouse and significantly enhances the generation of cytolytic cells in vivo after alloimmunization. No functional differences between native and the recombinant interleukin-2 molecules have been detected.
582 citations
TL;DR: In this paper, an alpha-helix-forming potential by amino acid substitutions from the native known sequences (rat/human and ovine CRF, sauvagine, and carp and sucker urotensin 1) led to the synthesis of an analog that was found to be more than twice as potent as either of the parent peptides in vitro.
Abstract: Polypeptide analogs of the known members of the corticotropin-releasing factor (CRF) family were synthesized and tested in vitro and in vivo for enhanced potency or competitive antagonism. Predictive methods and physicochemical measurements had suggested an internal secondary alpha-helical conformation spanning about 25 residues for at least three members of the CRF family. Maximization of alpha-helix-forming potential by amino acid substitutions from the native known sequences (rat/human and ovine CRF, sauvagine, and carp and sucker urotensin 1) led to the synthesis of an analog that was found to be more than twice as potent as either of the parent peptides in vitro. In contrast, certain amino-terminally shortened fragments, such as alpha-helical CRF or ovine CRF residues 8 to 41, 9 to 41, and 10 to 41, were found to be competitive inhibitors in vitro. Selected antagonists were examined and also found to be active in vivo.
484 citations
TL;DR: The adoptive transfer of lymphokine-activated killer cells in a murine B16 metastasis model led to a marked decreased in the number of lung nodules and improved survival and the use of IL-2-activated cells may provide a valuable method for the adoptive therapy of human neoplasms.
Abstract: In previous in vitro studies, we have shown that murine splenocytes or cancer patient lymphocytes incubated in IL-2 become lytic for fresh syngeneic or autologous tumors. We have now performed the adoptive transfer of such lymphokine-activated killer (LAK) cells in a murine B16 metastasis model to test their in vivo efficacy. 1 X 10(8) LAK cells, infused intravenously into C57BL/6 mice with established B16 pulmonary metastases, led to a marked decreased in the number of lung nodules and improved survival. LAK cells administered 3 d after amputation of a tumor-bearing limb also decreased the incidence of spontaneous pulmonary metastases. LAK cells generated from tumor-bearer splenocytes had effects equivalent to those from normal animals, and this antimetastatic effect of the LAK cells did not require the prior administration of cyclophosphamide or other immunosuppressants. Fresh or unstimulated splenocytes had no effect. The antitumor effectors and precursors in vivo and in vitro were Thy-1+. The lymphokine required for the activation appeared to be interleukin 2 (IL-2), since incubation in partially purified supernatants from PMA pulsed EL-4 or Con A-pulsed splenocytes or purified Jurkat IL-2 led to the generation of LAK cells equally active in vivo. The use of IL-2-activated cells may provide a valuable method for the adoptive therapy of human neoplasms as well.
379 citations
TL;DR: Investigations demonstrate that while the events occurring in liver microsomes in vitro appear to parallel those which take place in intact liver in vivo, the conditions in vivo make the spin-trapping studies of radicals in intact animals much more selective than it is in vitro for a given spin trap, and requires the use of more than one type of spin-Trapping agent to detect different radical species in vivo.
310 citations
TL;DR: Pertussis (whooping cough), a two-stage process of disease (respiratory colonization and toxin-mediated disease) is caused by B. pertussis, a pathogenic parasite with habitat only in human beings.
244 citations
TL;DR: FUT-175 was highly effective in that, for example, intravenous dosing at 3 mg/kg could completely protect guinea pigs from the lethal Forssman shock and was also found to be effective in trypsin-induced shock in mice, in lethality due to thrombin-thrombosis in mice and in kinin formation in the inflammatory process in rats.
238 citations
TL;DR: Ex vivo experiments with aryl 1,4-dialkylpiperazines suggested that these compounds may have the same relative specificity as dopamine uptake blockers in vivo, and these compounds should prove to be useful pharmacological agents.
233 citations
TL;DR: The absorption of two hydrophobic compounds through rat skin was measured by in vivo and in vitro techniques and the effect of the receptor fluids on the integrity of the skin barrier was assessed by measuring the permeability of control compounds.
232 citations
TL;DR: Perchloric acid extracts of radiation-induced fibrosarcoma (RIF-1) tumors grown in mice have been analyzed by multinuclear NMR spectroscopy and by various chromatographic methods, allowing the unambiguous assignment of the 31P resonances observed in vivo to specific phosphorus-containing metabolites.
216 citations
TL;DR: In vitro results suggest that the sis gene is responsible for at least part of the platelet-derived growth factor-like mitogenic activity secreted by cultured endothelial cells and indicate that the ss gene is readily activated in endothelium cells during the transition from in vivo conditions to in vitro growth as a monolayer on plastic.
Abstract: Recognition that the sis gene codes for a protein homologous with at least one of the two chains of platelet-derived growth factor has made it possible to directly assess transcriptional expression of platelet-derived growth factor both in cultured cells and in tissue obtained in vivo. We have found that a 3.7-kilobase RNA homologous to the sis gene is expressed at moderate levels in cultured human and bovine endothelial cells, at low levels in in vivo endothelium from human umbilical vein, and at very low levels in bovine aortic endothelium in vivo. This RNA migrates at the same rate as the previously reported sis band in the HUT 102 human T-cell lymphoma line. This band is not found in RNA extracted from freshly obtained bovine aortic media or from human foreskin fibroblasts or cultured fetal human aortic smooth muscle cells. Our in vitro results suggest that the sis gene is responsible for at least part of the platelet-derived growth factor-like mitogenic activity secreted by cultured endothelial cells and indicate that the sis gene is readily activated in endothelial cells during the transition from in vivo conditions to in vitro growth as a monolayer on plastic. Expression of the sis gene by endothelium in vivo raises the possibility that platelet-derived growth factor has a role in the development of the vascular system in the young animal and in the maintenance of the normal vascular system in the adult.
TL;DR: The conformational properties and in vitro and in vivo activity of a series of small peptides are reported and results of the biological studies are reported.
Abstract: A series of growth hormone-releasing peptides have been designed and tested for both in vitro and in vivo activity In vitro activity at 1-10 ng/ml was obtained for the pentapeptide, His-DTrp-Ala-Trp-DPhe-NH2 (I) and the hexapeptide, His-DTrp-Ala-Trp-DPhe-Lys-NH2 (II) These peptides, as well as others to be described, are active in releasing GH in vivo at low microgram dosages In this manuscript, the conformational properties and in vitro and in vivo activity of a series of small peptides are reported Results of the biological studies are reported in an accompanying paper
TL;DR: It is concluded that the presence of VIP receptors on T cells facilitates the entry of T cells into MLN and Peyer's patches in vivo, and it is proposed that this effect is mediated by T cell-VIP interactions in the vicinity of the specialized endothelium of those tissues.
Abstract: The capacity of T lymphocytes exposed in vitro to the neuropeptide vasoactive intestinal peptide (VIP) to bind VIP in vitro and to migrate to different tissues in vivo has been studied. VIP treatment of T cells resulted in a time- and dose-dependent loss of the ability of T cells to specifically bind radioiodinated VIP. Altered binding was due to a decrease in the expression of cellular receptors for VIP on the treated cells rather than an alteration in the affinity of the cells for the neuropeptide. Alteration of VIP receptor expression was not associated with a change in the expression of Thy-1, Lyt-1, or Lyt-2 surface markers by the treated cells. VIP treatment of T cells in vitro resulted, however, in a dose-dependent decrease in the ability of the treated cells to localize in mesenteric lymph nodes (MLN) and Peyer's patches of recipient animals at early times after cell transfer, and this was due to a selective decrease in the rate of accumulation of the treated cells in these tissues. There was no alteration in the distribution of VIP-treated cells in the blood, spleen, liver, or other major organs of the recipient animals. It is concluded that the presence of VIP receptors on T cells facilitates the entry of T cells into MLN and Peyer's patches in vivo, and it is proposed that this effect is mediated by T cell-VIP interactions in the vicinity of the specialized endothelium of those tissues.
TL;DR: The use of '9F NMR to monitor the metabolism of 5-fluorouracil in tumours and in the liver is described and the aim is to alter the rate and fate of metabolism of the drug and hence increase its therapeutic efficacy.
Abstract: The nuclear magnetic resonance (NMR) method makes it possible to analyse the chemical constituents of living animals or humans repeatedly and non-invasively. It has mainly been applied to the study of endogenous phosphorylated or carbon containing compounds (Gadian, 1982; Iles et al., 1982) but could equally be used to trace the metabolic fate of exogenously administered substances such as drugs. At present it is necessary to kill many animals in order to determine the fate of a drug at its target site (or at the sites where it is detoxified) and it is almost impossible to obtain such information in humans. By using new in vivo NMR techniques it should be possible to follow the metabolic fate of a drug either in an animal or patient. The most favourable atomic nucleus for studies of this kind is 19F: there is no background from endogenous compounds, 19F gives intense NMR signals with a wide chemical shift range, and many fluorinated drugs are in clinical use. In this paper we describe the use of '9F NMR to monitor the metabolism of 5-fluorouracil in tumours and in the liver. The fluorinated pyrimidines, 5-fluorouracil (5FU), 5-fluorouridine (FUrd) and 5-fluoro-2-deoxyuridine (FdU) are widely used in the treatment of disseminated human cancers, especially of the gastrointestinal tract, breast and ovary (Martindale, 1982). The metabolism of these drugs has been extensively studied and it is clear that with a few important exceptions they participate in the same pathways as uracil and its metabolites (Figure 1). Treatment with fluorinated pyrimidines produces two major effects in cells: (i) inhibition of DNA synthesis by inhibition of dTMP synthetase (EC 2.1.1.41) by fluorodeoxyuridine monophosphate (FdUMP) (Heidelberger, 1974); and (ii) alteration in the processing and function of some types of RNA because of extensive incorporation of 5FU in place of uracil (Heidelberger, 1974; Carrico & Glazer, 1979). Which of these effects accounts for the major antitumour property of these drugs is a matter of contention. Recent studies have been directed at developing combined chemotherapeutic regimens which incorporate the fluorinated pyrimidines with drugs such as methotrexate, thymidine or PALA (Goulian et al., 1980; Bedikian et al., 1981; Au et al., 1982) or. developing new analogues (Sakurai, 1981). In both cases the aim is to alter the rate and fate of metabolism of the drug and hence increase its therapeutic efficacy. Major problems in this area are the provision of precise methods with the ability to quantify all aspects of metabolism of the drug: its metabolites are unstable and difficult to detect. Pogolotti et al. (1981) and Sommadossi et al. (1982) have overcome many of these problems, but conventional analysis of uptake into solid tumour models has a number of difficulties, not least in satisfactory removal of the tissue. Studies on 5FU metabolism in cell culture cannot give information about the uptake or fate of the drug in an intact tumour (Pogolotti et al., 1981), while plasma pharmacodynamics give at best only a very indirect assessment of a drug's efficacy (Cano et al., 1981). We were able to follow the metabolism of i.v. injected 5FU in situ both in implanted tumours and livers of C57 mice by `9F-NMR using surface coils. Livers were examined in either female C57 or C57BI/Cbi mice. Lewis lung carcinomas were implanted in female C57BI/Cbi mice by s.c. injection of 2.5 x 104 viable tumour cells (obtained by trypsin/DNase digestion) over the sacral region and studied at a mean diameter of 6-7 mm. Animals were anaesthetised using sodium pentobarbitone 60mgkg-1 by i.p. injection. A 25mgml-1 solution of 5FU (Roche Products) was then injected into the jugular vein. For NMR spectroscopy mice were secured vertically within a purpose built probe. By means of an abdominal incision a flat one turn 7mm diameter radiofrequency (R.f.) coil was placed on the surface of the liver. To prevent evaporation and to electrically insulate the coil, the liver surface was covered with a thin plastic film. In the case of tumour-bearing mice the coil was laid over the
TL;DR: The data suggest that, although non-steroidal anti-inflammatory agents may inhibit discrete neutrophil functions both in vitro and in vivo, their effects do not duplicate those of polyenoic inhibitors of arachidonate metabolism.
TL;DR: Interspecies Comparison of In Vivo Caffeine Pharmacokinetics in Man, Monkey, Rabbit, Rat and Mouse as discussed by the authors, the authors compared the pharmacokinetics of mice, monkeys, rats, rats and mice.
Abstract: (1984). Interspecies Comparison of In Vivo Caffeine Pharmacokinetics in Man, Monkey, Rabbit, Rat and Mouse. Drug Metabolism Reviews: Vol. 15, No. 7, pp. 1355-1383.
Journal Article•
TL;DR: In vivo and in vitro procedures are used to select a subpopulation of cells from the human ovarian carcinoma cell line, NIH:OVCAR-3, with the capacity to grow i.p. in female nude athymic mice, well suited for the evaluation of new drugs and novel experimental therapies in ovarian cancer.
Abstract: We have used in vivo and in vitro procedures to select a subpopulation of cells from the human ovarian carcinoma cell line, NIH:OVCAR-3, with the capacity to grow i.p. in female nude athymic mice. After i.p. injection of these cells, animals develop metastatic spread similar to that of clinical ovarian cancer. Disease progression is characterized by the development of massive ascites, extensive invasive i.p. tumors, and pulmonary metastases. The malignant ascites cells are transplantable, manifest cytoplasmic androgen and estrogen receptors, and express the ovarian cancer associated antigen CA125 (116,000 units/ml of ascites supernatant). The cells also have the same chromosome markers which were present in the original cell line, NIH:OVCAR-3. Survival following i.p. passage of ascites is dependent on tumor cell inoculum ranging from a median survival of 39 days with 40 million cells to 84 days for 11.5 million transplanted cells. The characteristics of this unique in vivo model make it well suited for the evaluation of new drugs and novel experimental therapies in ovarian cancer. In addition, this in vivo model, together with ovarian cancer cell lines, may prove particularly useful for the study of pharmacological ways to specifically increase the cytotoxicity of anticancer agents in tumor cells while not increasing toxicity in normal tissues. The presence of hormone receptors should facilitate the experimental evaluation of hormonal therapy in ovarian cancer.
TL;DR: It is concluded that low-dose feeding of TBTO suppresses thymus-dependent immune responses as well as parameters of the nonspecific resistance and impaired in vivo splenic clearance was due to a reduction in both the number of adherent cells in the spleen and bacterial digestion on a cell for cell basis.
TL;DR: A hypothesis has been proposed to ascribe some of the EGF-like effects of TCDD, such as fatty infiltration of the liver and hyperplastic proliferation of gastric epithelia and epidermal cells to its action on the E GF receptor.
Abstract: The effect of in vivo-administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on epidermal growth factor (EGF) receptor activity of the rat hepatic plasma membrane was studied TCDD causes a significant reduction in EGF binding at an early stage of toxicity (day 2) and at very low doses (1 microgram/kg, single ip, rat) This reduction appears to be due to a decline in the number of receptors There is a good correlation between levels of decline in EGF binding and loss of body weight among TCDD-treated rats The reduction in EGF binding occurs at a relatively low dose in the guinea pig (a very sensitive species) and at high doses in the hamster (a tolerant species) Among three mice strains, TCDD (115 micrograms/kg, single ip) caused 98% reduction in EGF binding in the sensitive strains (C57BL/6J and CBA/J) but only a 50% reduction in the tolerant strain (AKR/J) To relate the above biochemical changes to in vivo effects, TCDD was postnatally administered (through mother's milk) to mouse neonates The most prominent toxic manifestations were early eye opening and incisor eruption, loss in body weight gain, and retardation of hair growth All of these symptoms have been ascribed to EGF effects TCDD was also found to stimulate phosphorylation of the EGF receptor in the rat hepatic plasma membrane This phosphorylation effect was observed at day 1 and persisted until the end of the test (day 10) It has long been recognized that agents causing reduction in number of EGF receptors (eg, phorbol esters) elicit in vivo cellular responses that are similar to those caused by exposure to excess doses of growth factors Accordingly, a hypothesis has been proposed to ascribe some of the EGF-like effects of TCDD, such as fatty infiltration of the liver and hyperplastic proliferation of gastric epithelia and epidermal cells to its action on the EGF receptor
Patent•
20 Mar 1984TL;DR: In this paper, the authors described a lipid matrix carrier for the sustained release of bioactive agents in vivo or in vitro, which provided high entrapment efficiencies, release of entrapped compounds in their active form, biodegradability and avoidance of vascular occlusion in vivo.
Abstract: Lipid matrix carriers are described which provide for the sustained release of bioactive agents in vivo or in vitro. The properties of the lipid matrix carriers of the present invention include high entrapment efficiencies; release of entrapped compounds in their active form; biodegradability and avoidance of vascular occlusion in vivo; and avoidance of sequestration of the bioactive agent in the liver and spleen.
TL;DR: In vivo significance of the kinetic parameters which characterize the interaction between proteinases and protein proteinase inhibitors are described and a stability time for enzyme-inhibitor complexes is defined as a minimal time during which the complexes may be considered as stable.
TL;DR: In vivo mouse zona compacta neurons exhibit the same electrophysiological and pharmacological properties as rat dopamine-containing neurons and in vitro mouse dopaminergic neurons fire with pacemaker regularity when in a low Ca2+/high Mg2+ environment, suggesting in vitro studies offer an approach to examine the basic properties of dopamine neurons exclusive of feedback pathways and other afferent inputs.
Journal Article•
TL;DR: It is proposed that the mechanism of lymphocyte extravasation involves a specific receptor-mediated binding event followed by an adenylate cyclase-dependent activation of cell motility in a manner similar to that reported for pancreatic islets and hormone-responsive cultured cell lines.
Abstract: Pertussigen, a protein toxin purified from Bordetella pertussis, and fucoidin, a high molecular weight sulfated polysaccharide, were analyzed for their ability to inhibit lymphocyte recirculation in vivo. Pertussigen treatment of lymphocytes resulted in a dosage- and time-dependent loss of their ability to localize in lymph nodes or Peyer's patches. This toxin-induced alteration did not reverse after extended lymphocyte culture in toxin-free media, and had no effect on lymphocyte viability or activation by mitogens. Furthermore, pertussigen-treated lymphocytes retained the ability to specifically adhere to high endothelial cells in an in vitro binding assay. Kinetic studies suggested that the toxin's molecular action on lymphocytes is analogous to that reported for pancreatic islets and hormone-responsive cultured cell lines. Inhibition of lymphocyte recirculation by fucoidin was also observed in vivo. Fucoidin-mediated inhibition of lymphocyte localization to peripheral lymph nodes was reversible with time, and could not be effected by pretreatment of lymphocytes with the polysaccharide. Furthermore, we confirmed the observation that fucoidin blocks lymphocyte adhesion to high endothelial cells in vitro. On the basis of these observations, we propose that the mechanism of lymphocyte extravasation involves a specific receptor-mediated binding event followed by an adenylate cyclase-dependent activation of cell motility. Fucoidin is capable of interfering with the primary adhesion event, whereas pertussigen selectively inhibits the second process to block lymphocyte recirculation in vivo.
TL;DR: This review summarizes recent data concerning the immunogenicity and immunomodulatory properties of glycosphingolipids and suggests a role for gangliosides as modulators of the immune response is not supported by physiologically relevant data at present.
TL;DR: It is found that for several antigens, administration of IFN-γ to mice leads to two- to five-fold enhancement of antibody formation provided that the IFn-γ and antigen are administered together.
Abstract: T lymphocytes produce a variety of immunoregulatory molecules including gamma interferon (IFN-γ)1–3 and antigen-specific suppressor and enhancer factors4–7. During our studies of active substances obtained from cloned T-cell lines, we observed that certain fractions administered to mice resulted in enhancement of immune responses. Preliminary characterization of the substance suggested that it could be IFN-γ and we therefore undertook a study of the action of IFN-γ produced by recombinant DNA methodology on immune responses. We found that for several antigens, administration of IFN-γ to mice leads to two- to five-fold enhancement of antibody formation provided that the IFN-γ and antigen are administered together. The effect was dose dependent, giving a maximal response at 500–600 anti-viral units per mouse. Preliminary studies suggest that the macrophage may be the target of IFN-γ action. Addition of IFN-γ to cultures of a macrophage cell line leads to a greater than 10-fold increase in the level of RNA coding for I-region-encoded cell surface molecules.
Journal Article•
TL;DR: It is found that normal human peripheral blood mononuclear leukocytes cultured in vitro and stimulated by antigens or T cell mitogens release a heat-labile, trypsin-sensitive protein that stimulates dermal fibroblasts to produce increased quantities of type I and III collagens, which suggest that this collagen production protein is of T lymphocyte origin and that it preferentially stimulates production of collagen.
Abstract: Increased collagen deposition is a common feature of granulomatous and nongranulomatous inflammation associated with certain types of cell-mediated immune reactions in vivo. In the present study, we found that normal human peripheral blood mononuclear leukocytes cultured in vitro and stimulated by antigens or T cell mitogens release a 100 to 170 K m.w., heat-labile, trypsin-sensitive protein that stimulates dermal fibroblasts to produce increased quantities of type I and III collagens. Our data suggest that this collagen production protein is of T lymphocyte origin and that it preferentially stimulates production of collagen. We also observed that human mononuclear leukocytes release a different effector molecule with an m.w. of 55 K that inhibits fibroblast collagen production. Mononuclear leukocytes in culture are capable of releasing both the stimulator and the inhibitor of collagen production. The relative amounts of each of these factors elaborated by mononuclear leukocytes in culture appear to be influenced by several variables, such as cell density, type of stimulant used, and the duration of the culture period. These observations suggest that collagen production by fibroblasts in close proximity to sites in vivo where cell-mediated immune reactions are occurring might be regulated by both of these effector molecules.
TL;DR: Although hippocampal slices differ metabolically from in vivo tissue, they exhibit a similar pattern of metabolic responses to ischemic and reflow conditions, which are very similar to those observed during in vivo ischemia.
Abstract: The transverse guinea pig hippocampal slice preparation was used to model the metabolic changes which occur in vivo during ischemia and recovery. Perfusing brain slices with medium devoid of glucose and oxygen elicits rapid decreases in phosphocreatine, ATP, intracellular pH, and in the evoked field potential recorded in the dentate gyrus. AMP and creatine rise during this period, while ADP and lactate levels remain unchanged. Cyclic AMP exhibits a transient increase in concentration. With the exception of ADP and lactate, these responses are very similar to those observed during in vivo ischemia. The return of glucose and oxygen to the incubation medium reverses these metabolic and electrophysiological effects and also leads to pronounced elevations in cyclic nucleotide concentrations. Metabolite concentrations approach, but do not reach, in vitro steady state levels during the first 30 min of recovery. Total adenylate and creatine steady state levels are approximately 50% of in vivo concentrations. The results suggest that, although hippocampal slices differ metabolically from in vivo tissue, they exhibit a similar pattern of metabolic responses to ischemic and reflow conditions.
TL;DR: The immunostimulating effects obtained in vivo are in agreement with the stimulation of interferon production observed in vitro and the inhibition of lymphocyte proliferation, however, cannot be reconciled with the Immunostimulatory action of G.S.s. observedin vivo.
Abstract: An aqueous extract of Panax Ginseng C.A. Meyer (G.S.) was prepared by boiling crushed G.S. roots in water. The extract obtained was adjusted to 125 mg G.S. per ml and was administered orally to mice for 5 to 6 days at the daily dose of 10, 50 and 250 mg G.S. per kg or was added to cultures of mouse spleen cells at concentrations varying between 0.25 and 8 mg G.S. per ml. The average total ginsenoside content of the G.S. roots used was determined by HPLC analysis and found to be 0.58% (w/w). Treated mice responded with enhanced antibody formation to either a primary or a secondary challenge with sheep red cells. The effects were dose-dependent. At the highest dose regimen, the primary IgM response was increased by 50% and the secondary IgG and IgM responses were increased by 50 and 100%, respectively. An even more pronounced effect was obtained with natural killer cell activity which was enhanced between 44 and 150% depending on the effector-to-target cell ratios used in the assay. In vitro, G.S. showed two main effects, an inhibition of stimulated and spontaneous lymphocyte proliferation at high, but not cytotoxic concentrations and an enhancement of interferon production particularly in non-stimulated spleen cells. The immunostimulating effects obtained in vivo are in agreement with the stimulation of interferon production observed in vitro. The inhibition of lymphocyte proliferation, however, cannot be reconciled with the immunostimulatory action of G.S. observed in vivo.
Journal Article•
TL;DR: It is concluded that 2.4G2 is a potent inhibitor of IgG Fc receptor-mediated immune clearance in vivo and had a small but significant inhibitory effect upon the clearance of 125I-labeled heat-aggregated HSA by the mononuclear phagocyte system both in intact and C5-deficient mice.
Abstract: To evaluate the feasibility of using a monoclonal anti-Fc receptor antibody to alter Fc receptor function in vivo, the disappearance of radiolabeled human serum albumin-rabbit anti-human serum albumin (HSA-anti-HSA) complexes was studied in mice before and after the infusion of 2.4G2, a monoclonal antibody (developed by J. Unkeless). 2.4G2 specifically binds to Fc receptors on mouse macrophages. Under standardized conditions, 6.1% of an i.v. administered dose of anti-HSA was sequestered in the liver of B6/D2J mice. When HSA-anti-HSA complexes were administered, 53.4% were sequestered. If 8 micrograms/g body weight of 2.4G2 was infused i.p. 1.5 hr before HSA-anti-HSA, only 13.7% of the infused complexes were sequestered in the liver. The inhibition in Fc receptor-mediated sequestration produced by this dose of antibody persisted for at least 24 hr. A dose of 1 to 2 micrograms/g was sufficient to inhibit sequestration by 50%. Animals receiving daily injections of 2.4G2 cleared immune complexes from their blood much more slowly than untreated animals. Because 2.4G2 was not cytotoxic to peritoneal macrophages in vitro in the presence of serum, and because comparable inhibition of Fc receptor function was observed in vivo in C5-deficient mice, blockade of function does not depend upon complement-mediated lysis of macrophages. The maximal degree of inhibition of Fc receptor function obtained by using intact 2.4G2 was about twice that observed by using Fab fragments of 2.4G2 to block receptors. In addition to its effect on Fc receptor function, 2.4G2 also had a small but significant inhibitory effect upon the clearance of 125I-labeled heat-aggregated HSA by the mononuclear phagocyte system both in intact and C5-deficient mice. We conclude that 2.4G2 is a potent inhibitor of IgG Fc receptor-mediated immune clearance in vivo.
TL;DR: It is concluded that broad low-amplitude electrograms in vivo and in vitro depict local areas of slow and/or discontinuous conduction, that the intrinsic asymmetry of cardiac activation due to fiber orientation is accentuated by infarction and may predispose to intraventricular reentry, and that intravent cardiac reentrant circuits that may be present on the epicardial surface may persist in a volume of myocardial tissue as small as 0.5 cc.
Abstract: Cardiac electrophysiologic studies were performed in three control dogs and in nine dogs with previous (8 to 22 days) anterior myocardial infarction. During programmed stimulation, no control dog had more inducible ventricular fibrillation (VF) or tachycardia (VT), three dogs with infarcts had inducible VF and six had inducible VT. Recordings in vivo were made via a plaque electrode containing 10 bipolar electrodes (3.0 x 1.5 cm) placed on the epicardial surface of the anteroapical left ventricle. Subsequently, epicardial strips (2 mm thick) from beneath the plaque were prepared for studies in vitro. Electrogram durations were significantly greater in dogs with infarcts than in control dogs both in vivo (p less than .05) and in vitro (p less than .001). Electrogram amplitudes were significantly lower in dogs with VT in vivo (p less than .05) and in vitro (p less than .001). In control animals activation was continuous and most rapid in the direction of fiber orientation; there were areas of slow and/or discontinuous conduction in all dogs with infarcts. In one case, sustained reentrant beating in vitro was caused by functional unidirectional block and microreentry at a site of continuous electrical activity during VT in vivo. Reentrant beating in vitro persisted in 0.5 cc of isolated tissue. We conclude that broad low-amplitude electrograms in vivo and in vitro depict local areas of slow and/or discontinuous conduction, that the intrinsic asymmetry of cardiac activation due to fiber orientation is accentuated by infarction and may predispose to intraventricular reentry, and that intraventricular reentrant circuits that may be present on the epicardial surface may persist in a volume of myocardial tissue as small as 0.5 cc.