Comparison of the immunodepressive action of microbial deamidases from different sources

The role of glutaminase activity of microbial deamidases in the immunodepressant action of these enzymes was studied. Escherichia coli asparaginase, asparagin and glutamin deamidases from Pseudomonas fluorescens and Mycobacterium album were found to have an inhibitory effect on the PHA-stimulated lymphocyte blast transformation. The inhibitory activity of deamidases with the asparaginase-glutaminase ratios 1 : 1.5 and 1 : 1.3 was one order of magnitude higher than that of Escherichia coli asparaginase with the ratio 1 : 0.02. It is assumed that glutaminase activity plays an essential role in the immunodepressant action of deamidases .     

Effect of cyclosporine on the lymphoid organs of CBA mice]

The influence of cyclosporine which is an immunodepressant on morphology of the lymphoid organs was studied on CBA mice. The immunodepressant was administered intramuscularly in a single LD50 and in a dose of 7 mg/kg for the treatment course of 21 days. The examinations were performed in various periods within 28 days after discontinuation of the drug use. It was shown that cyclosporine induced cell depletion in the thymus cortical and medullar zones, inhibition of lymphocyte mitotic activity, alteration of the Hassall corpuscles and impairment of their formation. It also induced devastation of the thymus-dependent zones in the mesenteric lymph nodes and spleen. When cyclosporine was used in the course doses the morphological changes in all the lymphoid organs were more marked. The morphological changes were reversible.     

Use of germ-free mice in experimental transplantation

A comparative study of skin allografts was performed in germ-free A/Ola mice kept in boxes and in A/Ola and BALB mice raised in ordinary conditions. Skin graft (of C57B1/6 mice) in A/Ola and BALB mice raised in ordinary conditions was shown to reject 16-21 and 12-18 days after the transplantation, respectively without cyclophosphamide (CP) use. CP application in BALB mice, grown in ordinary conditions, prolonged the lifespan of grafts to 12-29 days. The use of CP in germ-free A/Ola mice prolonged the lifespan of grafts to 19-39 days. In germ-free mice kept in boxes the use of an immunodepressant was not accompanied by infectious complications, while the animals kept in the vivarium often died of infectious diseases.     

Comparison of the antitumor, immunodepressive and toxic properties of carminomycin-albumin complexes differing in carminomycin content

Bovine serum albumin (BSA) and carminomycin, an anthracycline antibiotic, were subjected to conjugation with glutaraldehyde and their complexes with various contents of the antibiotic were prepared. The molar ratios of carminomycin and BSA were 8:1, 4:1, and 2:1. The antitumor effect of the preparations was studied on the models of mouse transplantable lymphosarcoma LIO equal 1 and ascitic forms of mouse lymphadenosis NK/Ly in vivo and in vitro. Their immunodepressant effect was evaluated from the decrease in the hemagglutinin titers in the mice immunized with sheep red blood cells. It was shown that when the toxicity of the complexes was the same, their antitumor and immunodepressant activities were different. The therapeutic activity of carminomycin in the four- and eight-substituted complexes was much higher than that of carminomycin alone. It is suggested that the differences in the activity of the complexes were connected with differences in their pharmacokinetics. It was found that the chemotherapeutic properties of the complexes may have changed by variation of the number of the cytostatic residues in the albumin molecule. The findings indicate that the whole complex molecule interacts with the malignant cell and not carminomycin preliminarily detached from it.     

Effect of cyclosporin on tumor xenotransplantation under the renal capsule in mice

Stimulating effect of cyclosporine on growth and invasiveness of tumor xenographts was studied on a model of rat solid sarcoma M-1 transplanted under the kidney capsule in mice. Cyclosporine was administered subcutaneously in a dose of 25 or 75 mg/kg on days 1-7. The stimulating effect of cyclosporine was directly associated with the immunodepressant dose and accompanied by a decrease in the thymus weight. With using cyclosporine the model of xenographts under the kidney capsule can be of value in screening cytostatics and immunomodulators.     

Suppression of humoral antibody synthesis on exposure to hyperbaric oxygenation

The influence of hyperbaric oxygenation (HBO) on the immune response in mice, immunized intraperitoneally with sheep red blood cells, was studied. HBO was shown to reduce hemagglutinin and hemolysin titres in peripheral blood as well as to decrease the amount of antibody-forming cells in the spleen. The most pronounced immunodepressant HBO effect is seen when hyperbaric oxygenation is carried out under toxic conditions before immunization of the animals with low antigen doses. Relationship is shown between the immunodepressant HBO effect and reduced leucocyte and lymphocyte counts in peripheral blood of the animals.     

The role of parasite-induced immunodepression,rank and social environment in the modulation of behaviour and hormone concentration in male laboratory mice (Mus musculus).

Peripheral immune responsiveness in male laboratory mice was reduced by infection with the trichostrongyloid nematode Heligmosomoides polygyrus. Responsiveness was also lower among high-ranking (aggressive) males regardless of infection status. Reduced responsiveness in both infected animals and high rankers was associated with elevated serum corticosterone concentration (a potential immunodepressant) and was compounded among high-ranking males by subsequent high aggressiveness. As in previous experiments, only low rankers modulated testosterone secretion in relation to current immunocompetence and corticosterone concentration. The lack of any downregulation of aggression in response to parasite-induced immunodepression contrasted with previous results using antithymocyte serum and may be due to the more localized nature of immunodepression during H. polygyrus infection. However, the additional increase in corticosterone concentration resulting from exposure to female odour and destabilized aggressive social relationships did result in downregulation of aggression among high rankers and of testosterone among mice generally, suggesting that modulation rules of thumb are at least partly dependent on the proximate cues associated with immunodepression.     

Prevention of early rejection of neural xenotransplants in the rat brain by the influence of magnetic field

The effect of alternating low-frequency (50 Hz, 40 mT) magnetic field (MF) on preventing of early rejection of xenotransplants (XT) of the chicken embryo forebrain, grafted in the brain parenchyma of adults rats, was studied. For this purpose, rats with XT were treated with 1-h-long MF applications over 1, 3, and 5 days following neurotransplantation. The animals with XT, but without treatment with MF, were used as a control. Morphological analysis of XT and neighboring brain tissues of recipients was performed 5 days after transplantation. It was found that the action of MF prevented or substantially weakened reactions of XT rejection at early stages after XT grafting in the brain of recipient rats. Destruction of the neighboring brain tissues was decelerated, while in the control group of animals destructions were clearly manifested. Positive effect of MF was observed even after single 1-h-long application of MF the next day after the operation, and it did not change when MF treatment was repeated 3 or 5 times during the following days. It is suggested that MF depresses some cellular reactions, in particular migration of lymphocytes and reactive gliosis, which cause early XT rejection. A possibility that the MF effect is due to activation of immunodepressant factor and/or to blockade of antigen receptors of the main histocompatibility complex on the donor and/or recipient cell surface cannot be ruled out.     

Sensitivity of BALB/c and WR strain mice to the immunodepressive action of cyclophosphamide and thiophosphamide

Experiments were made on BALB/cJ YSto and WR/Y mice to study the immunosuppressant action of cyclophosphamide (CP) and thiophosphamide (thiotepa) in vivo. WR mice were found to be significantly more sensitive to the immunosuppressant action of thiotepa than BALB/c mice and to have similar sensitivity to the action of CP. BALB/c mice appeared highly resistant to the action of both the drugs. Based on the data obtained and those reported in the literature a possible parallelism is suggested between the mutagenic and immunosuppressant action of CP and thiotepa.     

Characteristics of the reaction of the parathymic lymph nodes to pathogenic influences

Lymph nodes were studied on sections in white rats within 0.5 and 2 h after introduction of an antigen, an immunodepressant and upon stress. An early and distinct increase in the number of fat cells is observed in the parathymic lymph nodes in response to these effects. Already within 2 h, the reaction of parathymic nodes was not uniform and was determined by the character of experiments. No changes were noted at this time in the other lymph nodes.     

The role of the BCG dose and the mouse strain in the inhibition of development of neoplasms susceptible and nonsusceptible to the action of natural cytotoxic cells

The susceptibility of Ehrlich Ascites Carcinoma (EAC) cells to the action of natural cytotoxic cells of DBA/2 and Balb/c mice in vitro was established. Leukaemia L 1210 cells proved insensitive to the in vitro action of natural cytotoxic cells of DBA/2 mice, but not to those of Balb/c ones. BCG, one of the inductors of cytotoxic NK cells, when administered to DBA/2 or Balb/c mice before introduction of EAC cells inhibited the growth of this tumour but did not retard the development of leukaemia L 1210 in DBA/2 mice. The change in the number of peritoneal exsudate cells (PEC) in DBA/2 mice after intraperitoneal injection of BCG was demonstrated to be dependent on the dose and the time elapsed after bacilli introduction. The antitumour action of BCG does not depend on changes in the number of PEC caused by the bacilli. Both large (3.0 mg) and small (0.02 mg) doses of BCG inhibit the development of EAC in Balb/c mice ("sensitive" to BCG), notwithstanding the time of administration of the bacilli. In DBA/2 mice ("resistant" to BCG) development of EAC can be inhibited only by the large dose of BCG since small one is sometimes ineffective.     

Glucose-dependent insulinotropic polypeptide receptor null mice exhibit compensatory changes in the enteroinsular axis

The incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are gut hormones that act via the enteroinsular axis to potentiate insulin secretion from the pancreas in a glucose-dependent manner. Both GLP-1 receptor and GIP receptor knockout mice (GLP-1R(-/-) and GIPR(-/-), respectively) have been generated to investigate the physiological importance of this axis. Although reduced GIP action is a component of type 2 diabetes, GIPR-deficient mice exhibit only moderately impaired glucose tolerance. The present study was directed at investigating possible compensatory mechanisms that take place within the enteroinsular axis in the absence of GIP action. Although serum total GLP-1 levels in GIPR knockout mice were unaltered, insulin responses to GLP-1 from pancreas perfusions and static islet incubations were significantly greater (40-60%) in GIPR(-/-) than in wild-type (GIPR(+/+)) mice. Furthermore, GLP-1-induced cAMP production was also elevated twofold in the islets of the knockout animals. Pancreatic insulin content and gene expression were reduced in GIPR(-/-) mice compared with GIPR(+/+) mice. Paradoxically, immunocytochemical studies showed a significant increase in beta-cell area in the GIPR-null mice but with less intense staining for insulin. In conclusion, GIPR(-/-) mice exhibit altered islet structure and topography and increased islet sensitivity to GLP-1 despite a decrease in pancreatic insulin content and gene expression.     

Sensitivity of the splenic immunocompetent cells of mice with different genotypes to the action of alkylating agents

It has been established in experiments in vitro that splenocytes of DBA/2GSto mice are more sensitive to the immunosuppressant action of the alkylating agents (cyclophosphamide, sarcolysine and thiophosphamide) than splenocytes of BALB/cGLacSto mice. Splenocytes of C3H/SnRap mice exhibit and intermediate type of sensitivity. T-lymphocytes of the spleen of BALB/cGLacSto and DBA/2GSto mice are more sensitive in vitro to the action of active metabolites of cyclophosphamide as compared to B-lymphocytes, with both types of the cells of DBA/2GSto mice being affected to a greater extent than the cells of BALB/cGLacSto mice.     

Distribution and characterization of the TRH receptors in the CNS of ataxic mutant mouse

The distribution of TRH receptors in the membrane fraction of the CNS in ataxic mutant mice (C3Hf/Nem-rol and C57BL/6j-tg) was studied. TRH binding sites in cerebellum and frontal lobe of the ataxic form and the non-ataxic heterozygotes of Rolling Mouse Nagoya were decreased in comparison with the controls, whereas those in the spinal cord of Rolling Mouse Nagoya and cerebellum of Tottering Mouse were increased in the ataxic mice over the controls. Kinetic studies were performed on cerebrum and cerebellum of the different ataxic mutant mice. Such species differences in the distribution of the TRH receptors have to be considered in the action of TRH in individual ataxia cases.     

Influence of Ivabradine on the Anticonvulsant Action of Four Classical Antiepileptic Drugs Against Maximal Electroshock-Induced Seizures in Mice

Although the role of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in neuronal excitability and synaptic transmission is still unclear, it is postulated that the HCN channels may be involved in seizure activity. The aim of this study was to assess the effects of ivabradine (an HCN channel inhibitor) on the protective action of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) against maximal electroshock-induced seizures in mice. Tonic seizures (maximal electroconvulsions) were evoked in adult male albino Swiss mice by an electric current (sine-wave, 25 mA, 0.2 s stimulus duration) delivered via auricular electrodes. Acute adverse-effect profiles of the combinations of ivabradine with classical antiepileptic drugs were measured in mice along with total brain antiepileptic drug concentrations. Results indicate that ivabradine (10 mg/kg, i.p.) significantly enhanced the anticonvulsant activity of valproate and considerably reduced that of phenytoin in the mouse maximal electroshock-induced seizure model. Ivabradine (10 mg/kg) had no impact on the anticonvulsant potency of carbamazepine and phenobarbital in the maximal electroshock-induced seizure test in mice. Ivabradine (10 mg/kg) significantly diminished total brain concentration of phenytoin and had no effect on total brain valproate concentration in mice. In conclusion, the enhanced anticonvulsant action of valproate by ivabradine in the mouse maximal electroshock-induced seizure model was pharmacodynamic in nature. A special attention is required when combining ivabradine with phenytoin due to a pharmacokinetic interaction and reduction of the anticonvulsant action of phenytoin in mice. The combinations of ivabradine with carbamazepine and phenobarbital were neutral from a preclinical viewpoint.     

The effect of dalargin on stress-induced changes in the 5'-nucleotidase activity of the macrophages and in the level of endogenous blood cortisol in mice]

The action of dalargin, synthetic analogue of leuenkephaline, on stress-induced changes in 5'-nucleotidase activity and endogenous hydrocortisone levels was investigated in mice. It was found that there is a direct relation between the activity of 5'-nucleotidase and the level of hydrocortisone in CBA mice. For C57Bl/6 mice the relation was inverse. Dalargin is able to change the dependence from direct to opposite in CBA mice.     

The influence of damage factors of the different nature on the lipid composition in the mice liver

The combined effect of the X-rays at the dose of 4 and 5 Gy and the Tween 80 (the 0.3% solution) in the 10% solution of the water acetone on the lipid composition in the mice Balb/c liver is studied after 1 month. It is revealed that the disturbance of the linear dependence of "biological effect-dose" is due to the enhancement of the action of the acute X-rays with sublethal doses after the preliminary administration of the low toxic chemical agents at low doses on the lipid composition of the mice liver. The decrease of differences in the scale of the correlation between the generalized phospholipid composition parameters in the mice liver after combined action of the chemical and physical factors is shown. The interrelation between the mice Balb/c survival and the ratio of the general phospholipid fractions of the lipid liver in the age control groups is found.     

Growth hormone action in the developing neural retina: a proteomic analysis

The possible presence and action of growth hormone (GH) in the neural retina was investigated in newborn mice. The neural retina was found to be a site of GH gene expression, as GH mRNA was abundant in cells of the retinal ganglion cell layer, in which GH was also detected. It was also a site of GH action, since GH receptor (GHR) immunoreactivity mirrored that of GH. Actions of GH within the eye were indicated by a reduction in its axial length and retinal width (its neuroblastic, inner plexiform, and optic fiber layers) in GHR gene disrupted mice (GHR-/-), in comparison with wild type (GHR+/+) littermates. In the absence of GH signaling, four proteins in the retinal proteome of the GHR-/- mice (identified by 2-D gels and MS) differed in abundance with those in the wild type mice. Brain abundant membrane attached signal protein-1 (BASP-1) was down-regulated, whereas protein kinase C inhibitor 1, cyclophilin A, KH domain-containing, RNA-binding, signal transduction-associated protein 3 were up-regulated in GHR-/- mice. These proteins are involved in retinal vascularization, neural proliferation and neurite outgrowth. GH might thus have hitherto unsuspected roles in these processes during retinal development.     

Effects of hypophysectomy and the insulin-like and anti-insulin pituitary peptides on carbohydrate metabolism in yellow Avy/A (BALB/c x VY)F1 hybrid mice

The amino-terminal portion of human growth hormone, residues 1-43 (hGH1-43), has insulin-potentiating action, while a hyperglycemic pituitary peptide (HP), which co-purifies with human growth hormone (hGH), is antagonistic to the action of insulin. The effects of hGH, hGH1-43, and HP on glucose metabolism were assessed in young (4-5 weeks) and adult (6-8 months) hypophysectomized yellow Avy/A mice which lacked any interfering endogenous pituitary hormones, and compared with age-matched intact obese yellow Avy/A and lean agouti A/a mice. Treatment with hGH1-43 or HP did not promote body growth in hypophysectomized yellow mice; but after 2 weeks of treatment with hGH, there was a significant increase in body weight (P less than 0.05). Treatment with HP raised blood glucose and lowered insulin concentrations in obese yellow mice, but not in agouti or hypophysectomized yellow mice. The severely impaired glucose tolerance of the hypophysectomized yellow mice was improved by acute (60 min) and chronic (3 days) treatment with hGH1-43 as well as by 2 weeks of treatment with hGH; in contrast, HP had no effect. Glucose oxidation in adipose tissue from obese yellow mice was low and showed essentially no response to stimulation by insulin at doses lower than 1000 microunits/ml. Basal glucose oxidation rates in adipose tissue taken from agouti and hypophysectomized yellow mice were significantly higher (P less than 0.001) than those in tissue from obese yellow mice, and the rates responded significantly (P less than 0.05) to 100 microunits/ml insulin. The insulin binding affinities in liver membranes from agouti mice were higher than those from either obese or hypophysectomized yellow mice. The insulin receptor densities were similar in both agouti and obese yellow mice, but higher in hypophysectomized yellow mice (P less than 0.05). Treatment with hGH1-43 slightly increased, although not significantly, the insulin receptor density in yellow obese mice while hGH showed essentially no change. Therefore, hypophysectomy appeared to increase tissue response and decrease insulin resistance by increasing receptor numbers and lowering the circulating insulin levels. Furthermore, the insulin-like action of hGH was elicited directly in vivo by hGH1-43 in hypophysectomized yellow mice.