Showing papers on "In vivo published in 1981"

Sister-chromatid exchanges: a report of the GENE-TOX program.

Abstract: This paper reviews the ability of a number of chemicals to induce sister-chromatid exchanges (SCEs). The SCE data for animal cells in vivo and in vitro, and human cells in vitro are presented in 6 tables according to their relative effectiveness. A seventh table summarizes what is known about the effects of specific chemicals on SCEs for humans exposed in vivo. The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.

Transport of protein-bound hormones into tissues in vivo.

Abstract: THE STEROID and thyroid hormones circulate in the plasma tightly bound by albumin and by specific plasma globulins (1, 2). Consequently, hormones exist in two states at equilibrium in vitro, i.e. free (dialyzable) and protein-bound. A widely held hypothesis in endocrinology is that the fraction of hormone that is free in vitro is equivalent to the fraction of hormone that is free and available for transport into tissues in vivo. Therefore, in vitro measurements of free hormones may be commonly used as reliable indices of the free hormone in vivo for a variety of clinical states. The purpose of this review is to advance the concept that the large protein-bound moiety of plasma hormone is available for transport into tissues. Consequently, the fraction of plasma hormone that is available for transport in vivo may deviate greatly from the free fraction in vitro. Under some conditions, changes in the free hormone fraction in vitro and in the fraction of plasma hormone that is available for transport in vivo w...

Lethal myocardial ischemic injury.

Abstract: The biologic changes occurring in severely ischemic myocytes in vivo as the affected cells pass through the phase of reversible to the phase of lethal or irreversible injury are reviewed with special emphasis on the effect of ischemia on the production and utilization of highenergy phosphate, the destruction of the adenine nucleotide pool, and the appearance of signs of damage to the plasma membrane of the sarcolemma. Evidence is presented that indicates that the events occurring in severe ischemia in vivo are essentially identical to those found in total ischemia in vitro except that the biologic changes of ischemia develop more slowly in total ischemia in vitro than in severe ischemia in vivo. The slower time course of injury, together with the uniformity of injury provided by total ischemia in vitro, may allow for more precise identification of potential lethal cellular events in ischemic injury. The production of highenergy phosphates (HEP) from anaerobic glycolysis have been estimated in both in vivo and in vitro ischemia by the measurement of lactate accumulation, and total HEP utilization has been estimated from the depletion of stores of preformed HEP. The results show that between 80% and 90% of the HEP utilized by ischemic dog left ventricle is produced by anaerobic glycolysis. The onset of irreversibility is associated with marked depletion of the HEP and adenine nucleotide pools of the tissue and the cessation of energy production via glycolysis. The cessation of anaerobic glycolysis may be caused by the low sarcoplasmic, adenosine triphosphate (ATP) concentration of the dying myocyte. In addition to the foregoing changes, irreversibly injured tissue exhibits both ultrastructural and functional evidence of disruption of the plasmalemma of the sarcolemma. The possible relationships, causal and otherwise, between severe HEP depletion and membrane damage are discussed. Both HEP depletion (ATP < 3-8% of control) and membrane damage are considered to be objective signs of the presence of irreversible myocardial ischemic injury. However, at the present time, there is no proof that these changes are causally related either to each other or to cell death in severe in vivo ischemia.

In vivo effects of anti-asialo GM1. I. Reduction of NK activity and enhancement of transplanted tumor growth in nude mice.

Abstract: Intravenous injection of anti-asialo GM1, which has been shown to eliminate natural killer (NK) activity in vitro in the presence of complement, completely abolished NK activity against lymphoma cell line (YAC-1) in spleen cells from athymic nude mice as well as from conventional mice. An immunofluorescence study revealed a decreased number of asialo GM1 positive cells in the spleens of mice injected with anti-asialo GM1 than in those of mice injected with normal rabbit serum. In the nude mice with reduced NK activity, incidence of tumor take and the growth were enhanced when syngeneic (RL male-1), and allogeneic (YAC-1) tumors and human tumors were transplanted subcutaneously. These results strongly suggest that NK cells play an important role in transplanted-tumor growth in vivo.

Total ischemia in dog hearts, in vitro. 1. Comparison of high energy phosphate production, utilization, and depletion, and of adenine nucleotide catabolism in total ischemia in vitro vs. severe ischemia in vivo.

Abstract: This study was done to compare rates of high energy phosphate (HEP) utilization and depletion, as well as the production and distribution of catabolic products of adenine nucleo tides in dog heart during total ischemia in vitro and severe ischemia in vivo. Both HEP production from anaerobic glycolysis and HEP utilization occurred much more quickly during the first 15 mmtuet of severe ischemia in vivo than in total ischemia in vitro. HEP utilization exceeded production in both types of ischemia and tissue HEP decreased progressively. Much of the creatine phosphate (CP) was lost within the first 1–3 minutes; adenosine triphosphate (ATP) depletion occurred more slowly than CP and more slowly in vitro than in vivo. ATP was reduced from control contents of 5–6 μmol/g to 1.0 μmol/g by 75 minutes of total ischemia in vitro, but reached a similar level within only 30 minutes of severe ischemia in vivo. HEP utilization and production during ischemia were estimated from the rate of accumulation of myocardial lactate and essentially ceased when the ATP reached 0.4 μmol/g wet weight. At this time, more than 80% of the HEP that had been utilized in ischemia in vivo or in total ischemia in vitro had been derived from anaerobic glycolysis. ATP depletion was paralleled by dephosphorylation of adenine nucleottdeg. The lost nucleotides were recovered stoichiometrically as adenosine, inosine, hypoxantbine, and xanthine in both models of ischemia, a finding which demonstrates that the low collateral flow of severe ischemia allows little washout of nucleosides, bases, or lactate to the systemic circulation. These results Indicate that total ischemia in vitro can be used as a model of severe ischemia in vivo in that the pathways of energy production and depletion and of adenine nucleotide degradation generally are similar.

Tumor shedding and coagulation

Abstract: Three syngeneic carcinomas from two species shed plasma membrane vesicles when cultured in vitro or grown in the ascites tumor form in vivo. Shed vesicles carry procoagulant activity that can account for the activation of the clotting system and the fibrin deposition associated with these and many other types of malignancy in animals and man.

Role of Platelets in Tumor Cell Metastases

Abstract: Platelets may have a role in the development of animal tumor metastases. Ultrastructural studies in vivo have shown arrested tumor emboli surrounded by platelets. Several tumor cell lines induce thrombocytopenia in vivo. Certain tumor cells aggregate platelets in vitro. Correlations exist between the ability of some tumor cells to aggregate platelets in vitro and their metastatic potential in vivo. Antiplatelet agents have impaired or altered the spread of certain tumor metastases. It is suggested that platelets have a role in the sequestration, adherence, and penetration of tumor cells through the blood vessel endothelial cell barrier, thus preventing their rapid clearance from the circulation and allowing extravascular formation of nests of cells. Antiplatelet agents, particularly prostaglandins, may prove useful in preventing experimental animal metastases when administered before the inoculation of tumor cells. Their potential in human malignancy, where the patient presents with an established tumor, remains to be established.

Immunotoxins: hybrid molecules of monoclonal antibodies and a toxin subunit specifically kill tumour cells

Abstract: Several attempts to attack tumours in experimental systems have been made using conjugates of chemotherapeutic agents or potent toxins with antibodies (immunotoxins). In vitro studies have been highly successful, showing target specificity of a high order in some cases. However, so far, such conjugates have been inadequate in vivo, probably for two main reasons. First, conventional heteroclonal antibodies are perhaps inappropriate, because purification by biochemical methods leaves a large amount of non-antibody gamma-globulins. The use of monoclonal antibodies may overcome this problem. Second, when whole toxins have been conjugated to antibodies there has been a strong residual nonspecific cytotoxicity due to the binding capacity of a subunit, the B-piece of the toxin. (Diphtheria toxin or ricin consist of two polypeptide subunits. The A-piece is responsible for inhibition of protein synthesis on ribosomes, and the B-piece binds to galactose residues on the cell membrane and facilitates the transmembrane passage of the A-piece.) In the present work the problem of nonspecific binding by the B-piece has been circumvented by using the A-piece only as the toxin component of immunotoxins; these immunotoxins are active both in vitro and in vivo.

Time course of changes in porcine myocardial phospholipid levels during ischemia. A reassessment of the lysolipid hypothesis.

Abstract: This study was performed to determine the early and delayed metabolic effects of myocardial ischemia on the major membrane phospholipids and to reassess the potential role of lysophospholipids in the genesis of malignant dysrhythmias induced by ischemia. Samples taken from in situ hearts before ant at various intervals up to 40 minutes after abrupt ligation of LAD were extracted by the classical Folch technique with modifications to avoid artifactual lysophospholipid production and losses. Following thin layer chromatography of lipid extracts, phospholipid fractions were quantified by phosphorus estimation and lysophospholipids by a more sensitive method employing gas liquid chromatography. The total phospholipid content with the exception of lysophospholipids remained essentially constant throughout the early phases of acute ischemia, but fell by 6 and 14% after 8 and 24 ours, respectively. At 8 minutes, lysophospholipid levels n ischemic myocardium were significantly increased by 60% compared to pre-occlusion controls in the ischemic zone and by 25% in post-occlusion controls. They changed little thereafter. The molecular species of lysophospholipids remained unchanged throughout the period of ischemia studied. The mole fraction of other phospholipids as well as their fatty acyl and aldehyde profiles also were unchanged. Despite significant elevations in lysophospholipids levels, their absolute quantities were very small (0.6% of total phospholipid P) and 15-fold smaller than that reported in vitro to simulate electrophysiological manifestation of ischemia. However, such small amounts in vivo, if produced in the microenvironment of certain membrane-bound enzymes along with acidosis, hypoxia, and fatty acids, could be potentially deleterious to cell functions.

Noninvasive tomographic study of cerebral blood flow and oxygen metabolism in vivo. Potentials, limitations, and clinical applications in cerebral ischemic disorders.

Abstract: The non-invasive continuous inhalation technique of C15O2 and 15O2 coupled with positron emission tomography (PET) provides brain images that are thought to represent local cerebral blood flow (CBF) and oxygen extraction fraction (OEF). Experimental studies in baboons have confirmed that C15O2 inhalation allows tomographic measurement of CBF. The numerous difficulties involved in PET absolute quantitation are stressed, as well as some limitations inherent to the l5O inhalation model. However, the values for local CBF, OEF and CMRO2 obtained in normal young subjects are satisfactory in view of the above-mentioned limitations. The clinical application to recent cerebral infarction has allowed two opposite types of flow-metabolism uncoupling to be identified, which appear to be often predictive of tissue prognosis. The time course of spontaneous changes in CBF and OEF within the infarct is also described. Our studies have, in addition, revealed the previously unknown phenomenon of ‘crossed cerebellar diaschisis’ in supratentorial infarction. Lastly, a state of chronic watershed ischemia, potentially reversible by surgical revascularization, has been identified as presumably involved in the progression of watershed necrosis. The clinical potentials of this method appear considerable.

Trauma-induced protein in rat tissues: a physiological role for a "heat shock" protein?

Abstract: Hyperthermic shock induces the synthesis of a novel protein (P71) in many rat tissues in vivo. In incubated rat tissue slices P71 is the major protein synthesized even though it is undetectable in the tissues of a normal, unstressed rat. P71 is "heat shock" protein, and it may be induced in vivo by stimuli other than hyperthermia. These results indicate that caution must be used in studies of protein synthesis in tissue explants, since the pattern of proteins synthesized by rat tissue slices is characteristic of stressed tissue.

In vivo effects of antibodies to immune response gene products: prevention of experimental allergic encephalitis.

Abstract: Prevention of experimental allergic encephalitis in SJL/J [H-2s] mice was achieved with in vivo administration of antibody reactive with I-As gene products prior to immunization with spinal cord antigen. No protection was evident in animals that received antisera specific for I-Js gene products. Administration of antibody to I-As beginning 5 days after immunization with spinal cord antigen delayed, but did not prevent, the onset of experimental allergic encephalitis.

The antiplatelet and cardiovascular actions of a new carbacyclin derivative (ZK 36 374)--equipotent to PGI2 in vitro.

Abstract: The vascular and antiplatelet activities of a new, chemically stable carbacyclin derivative (ZK 36 374) were investigated and compared to PGI2. ZK 36 374 dose-dependently relaxed bovine coronary artery strips in vitro but was without direct effects on strips of bovine coronary veins which were contracted by PGI2. ZK 36 374 dose-dependently inhibited the ADP-, thrombin- and collagen-induced platelet aggregation in human platelet-rich plasma and disperded preformed platelet aggregates in whole blood of cats ex vivo. The IC50 was 0.2–1.1 (antigaggregation) and 13 (disaggregation) nM, respectively, and in the same range as PGI2. The maximum antiplatelet dose of ZK 36 374 (resolution of platelet aggregates) in anaesthetized cats in vivo was 0.45 nmoles/kg x min, and could be increased up to 3 nmoles/kg x min, i.e. 6–7-fold without significant changes in arterial blood pressure and heart rate. This indicates an appreciable dissociation between antiplatelet and blood pressure-lowering activities of this compound, at least in this model. It is concluded that ZK 36 374 is the first, chemically stable prostacyclin-mimetic agent that is equipotent to PGI2 in vitro and might be superior to PGI2 in vivo because of a reduced blood pressure-lowering activity.

SR-2508: A 2-nitroimidazole amide which should be superior to misonidazole as a radiosensitizer for clinical use

Abstract: Using a combination of toxicological, pharmacological and radiosensitization experiments on cells in vitro and tumors in vivo , we have selected two 2-nitroimidadole amidos which should prove superior to misoaidazole (MIS) for clinical use. The two drugs, SR-2508 and SR-2555, are considered to be close to the optimum for variants of misonidazole of the same electron affinity; their main difference is a lower lipophilicity than MIS. This lower lipophilicity leads to poorer penetration into neural tissues than that of MIS and this leads, as expected, to lower neurotoxicity of these drugs compared to MIS (as judged by an accelerating rotarod test following 4–5 weeks of daily injections). The in vitro radiosensitization tests on hypoxic Chinese hamster ovary HA-1 cells show that SR-2508 and MIS have the same radiosensitization efficiency but are slightly more potent as radiosensitizers than SR-2555. For the in vivo radiosensitization experiments we used the in vivo-in vitro cloning assay with the EMT6 tumor, the regrowth assay with RIF-1 and KHJJ tumors and the TCD 50 assay with the MDAH/MCa4 carcinoma. All show roughly equivalent levels of radiosensitization of both SR-2508 and SR-2555 to MIS although, as predicted by the in vitro results, SR-2555 is slightly inferior to SR-21.508. We conclude that, although SR-2555 appears to be slightly less neurotoxic than SR-2508, its lower radiosensitizing efficacy is likely to make it less attractive than SR-2508 as a replacement for MIS for clinical use. Extrapolating the neurotoxicity data obtained in the mouse together with pharmacological studies of SR-2508 in spontaneous tumors of the dog, we estimate that levels of SR-2508 of at least 7.5 times those of MIS will be able to be achieved in human tumors for the equivalent level of neurotoxicity. This should enable essentially maximum radlosensitization of the hypoxic cells in human tumors to be obtained in conventional daily fractionation.

Site-specific, sustained release of drugs to the brain

Abstract: A dihydropyridine-pyridinium salt type of redox system is used in a general and flexible method for the site-specific or sustained delivery (or both) of drugs to the brain. A biologically active compound linked to a lipoidal dihydropyridine carrier easily penetrates the blood-brain barrier. Oxidation of the carrier part in vivo to the ionic pyridinium salt prevents its elimination from the brain, while elimination from the general circulation is accelerated. Subsequent cleavage of the quaternary carrier-drug species results in sustained delivery of the drug in the brain and facile elimination of the carrier part.

Inhibition of basophil histamine release by anti-inflammatory steroids.

Abstract: The release of histamine from human leukocytes is a useful in vitro model for studying allergic disease1. Many of the drugs used in the treatment of allergy and asthma (for example, isoprenaline and theophylline) are effective inhibitors of in vitro histamine release2. However, the anti-inflammatory steroids have not been found to inhibit the in vitro release of histamine from mast cells or basophils activated by immunological stimuli3–6. In view of the fact that the in vivo anti-allergic effects of steroids occur only 12‐24 h after administration7, we have re-examined the effects of these drugs on IgE-mediated histamine release from human basophils after prolonged incubations. We report here a time-dependent inhibition of histamine release from human basophils by glucocortico-steroids. The relative activity of a series of steroids as inhibitors of histamine release correlates well with the relative in vivo anti-inflammatory activity of the same compounds. These results suggest that the basophil may be an in vivo target of the anti-inflammatory steroids and that inhibition of this cell type may account for some of the activity of steroids in preventing inflammation.

Complement-induced granulocyte aggregation in vivo.

Abstract: Previous studies from our laboratories have demonstrated that granulocytes (PMNs), when exposed to activated complement (C) (specifically C5a), will aggregate and be provoked to damage cultured endothelial cells in vitro; it was postulated that these phenomena might also occur in vivo, constituting a previously unsuspected mechanism of immune tissue damage. The studies here presented confirm by intravital microscopy that PMN aggregation and leukoembolization in fact occur in live animals when C is activated or C5a is infused, and that these are accompanied by extravasation of plasma proteins in a pattern suggesting endothelial damage. It is concluded that altered microvascular behavior of PMNs is a possible pathogenetic mechanism in disease states associated with C activation.

Influence of in vivo hydrocortisone on some human blood lymphocyte subpopulations. I. Effect on natural killer cell activity.

Abstract: The effect of in vivo hydrocortisone (OHC) on natural killer (NK) activity was studied using the K562 cell line as target in a 3-h 51Cr-release assay Peripheral blood lymphocytes obtained from five normal volunteers at 0, 4, 24 and 48 h after intravenous administration of 300 mg of OHC showed significantly increased NK activity at 4 h, decreased activity at 24 h, with a return toward normal at 48 h Parallel variations were found in the fraction of lymphocytes bearing receptors for the Fc part of IgG However, neither the number of these cells nor the NK activity was influenced by the medication when the results were given per millilitre blood In vitro preincubation of the effectors with OHC for 24 h had no effect on viability, expression of surface markers, or NK activity It is concluded that under the present conditions NK activity is OHC-resistant The variations observed after in vivo administration seem to be due to a reversible redistribution mainly affecting cells other than the NK effectors

In vivo carbon-13 nuclear magnetic resonance studies of mammals.

Abstract: Natural abundance carbon-13 nuclear magnetic resonances (NMR) from human arm and rat tissues have been observed in vivo. These signals arise primarily from triglycerides in fatty tissue. Carbon-13 NMR was also used to follow, in a living rat, the conversion of C-1-labeled glucose, which was introduced into the stomach, to C-1-labeled liver glycogen. The carbon-13 sensitivity and resolution obtained shows that natural abundance carbon-13 NMR will be valuable in the study of disorders in fat metabolism, and that experiments with substrates labeled with carbon-13 can be used to study carbohydrate metabolism in vivo.

The 9L rat brain tumor: Description and application of an animal model

Abstract: Animal models allow determination of tumor response to anticancer agents under various experimental conditions. The chemically induced 9L rat brain tumor has been developed as both in vivo and in vitro models. Animal survival, clonogenic cell survival, and tumor growth delay provide means to measure the effectiveness of treatment modalities in this tumor model. Monolayer cultures, multicellular spheroid cultures, brain tumors, and flank tumors have been used to study the influence of different biological entities of the 9L model on the response to treatment with radiation and/or BCNU (1,3- bis (2-chloroethyl)-1-nitrosourea).

Lyt-23+ cyclophosphamide-sensitive T cells regulate the activity of an interleukin 2 inhibitor in vivo.

Abstract: Sera of thymus-bearing normal mice contain high levels of Interleukin 2 (II-2) inhibitor, whereas sera of athymic nu/nu mice do not. Evidence is presented that cyclophosphamide-sensitive Lyt-23+ T cells induce high II-2 inhibitor activity in the recipient nu/nu mice in the course of a graft-vs.-host reaction. The II-2 inhibitor has an approximately 50,000 mol wt. Its function is neither antigen specific nor H-2 restricted. During ontogeny, its activity parallels the development of T cell reactivity, i.e., it is absent both in the amniotic fluid and in sera of unborn mice, but increases to high levels during the early postnatal phase. The II-2 inhibitor described is viewed as an example of a T cell-dependent, in vivo regulatory mechanism able to effectively counteract the nonspecific activity of the Lyt-1+ helper T cell-derived II-2. Because the II-2 inhibitor activity is rather high in vivo, II-2 activity will exist only in close proximity to its producer cell, thereby maintaining specificity during the in vivo induction of cytotoxic T lymphocytes

Thyroxine Metabolism in the Low Thyroxine State of Critical Nonthyroidal Illnesses

Abstract: This study reports in vitro and in vivo parameters of T4 metabolism in patients with critical nonthyroidal (illnesses who were selected because of serum total T4 values less than 3µg/dl and normal TSH levels. Despite the depressed total (T)4 concentrations, the normal serum free T4 values (7 of 9 patients), T4 production rates (8 of 9), and TSH responses to TRH (8 of 8) provided evidence for normal free T4 availability to peripheral tissues. Elevated rT3 values in 10 of 14 patients were consistent with this view. However, serum free T4 index (determinations markedly underestimated free T4 (20 of 20). This resulted from failure of the T3 uptake measurement to reflect the defective state of serum T4 binding. Defective serum T4 binding to carrier proteins was evidenced by the 2- to 3-fold increase in both the free fraction and the MCR values for T4. The normal early distribution phase, despite defective serum T4 binding, suggested an additional abnormality of deficient extra-vascular T4 binding. The blunted ...

Regulation of macrophage populations. II. Synthesis and expression of Ia antigens by peritoneal exudate macrophages is a transient event.

Abstract: We have evaluated the biosynthesis and surface expression of I-A antigens by peritoneal macrophages and found that both events terminated during the 1st day in culture, in contrast to the undiminished synthesis and expression of H-2K antigens. This pattern was observed regardless of the means by which the macrophages were elicited, but was subject to modulation for a limited period of time in vitro: phagocytic stimuli were able to augment both I-A synthesis and expression. The loss of I-A and the re-expression after phagocytosis were both reflected in the stimulatory capacity of these macrophages in the mixed leukocyte reaction. Moreover, we found that I-A-bearing macrophages were lost from the exudate in vivo after irradiation. Our data suggest that, as in vitro, this phenomenon is due to the transition of individual macrophages from I-A-positive to I-A-negative, and that constant renewal is required to maintain the I-A-bearing subset in vivo.

Effect of N-[(S)-1-carboxy-3-phenylpropyl]-L-Ala-L-Pro and its ethyl ester (MK-421) on angiotensin converting enzyme in vitro and angiotensin I pressor responses in vivo.

Abstract: The parent diacid (N-[(S)-1-carboxy-3-phenylpropyl]-L-Ala-L-Pro of MK-421 inhibited hog plasma angiotensin converting enzyme (ACE) by 50% (I50) at a concentration of 1.2 nM and was 17 times more potent than captopril. In vitro the I50 for MK-421, an ethyl ester, was 1200 nM because de-esterification did not occur. Similarly in the guinea-pig ileum, the diacid inhibitor and MK-421 potentiated the contractile effects of bradykinin at an AC50 of 77 pM and 18 nM, respectively. Inhibition of the pressor effects of angiotensin I by the diacid ACE inhibitor occurred at an ID50 of 8.2 micrograms/kg i.v. in rats and 6.4 micrograms/kg i.v. in dogs. Thus, the diacid was approximately 12 times more potent than captopril. The ID50 for MK-421 was 14 and 278 micrograms/kg i.v. in rats and dogs, respectively, because of differences in the rates of de-esterification. Oral ACE inhibitory activity was determined by blockade of the pressor effects of angiotensin I in conscious rats and dogs. In rats, but not in dogs, the diacid inhibitor was poorly absorbed, whereas MK-421 was well absorbed in both species. MK-421 inhibited the pressor effects of angiotensin I at 0.1 to 3.0 mg/kg p.o. for at least 6 hr in rats and dogs, and compared to captopril was 8.6 times more potent in rats and 4.6 times more potent in dogs. These data demonstrate that MK-421 and its parent diacid are potent, long-lasting orally active inhibitors of ACE. In addition, the low activity of MK-421 in vitro contrasts with its substantial in vivo activity, and supports the hypothesis that MK-421 is a prodrug that first must be de-esterified to permit full expression of its significant in vivo pharmacological activity.