Nature of inhibition of the activity of macromolecular antibodies]

The presence in the organism of an inhibitory factor expressing its activity under conditions of increased macromolecular globulins production (of M-immunoglobulins in particular) was established experimentally. The inhibitory factor depressed the avidity of the macromolecular antibodies; its appearance preceded reduction of the macromolecular protein level in the blood serum. The inhibitory effect of the blood serum in blood letting and vaccination with bacterial antigen is connected with the blood serum albumins, and with increased cystein and sulfhydryl groups concentration.     

Leukocytolysis and phagocytosis under hyperosmotic conditions]

PAN and leukocytolysis were measured in dog blood placed in hypo- and hypertonic solutions of glycerin and glucose (1:10). It was found that leukocytolytic activity of the substances depends on equimolar concentrations of nonelectrolytes. It is more pronounced in hypo- than in hypertonic conditions. Glycerin is 3-5-times more active than glucose. In concentrations 2.0 M for glycerin and 0.5 M for glucose leukocytolysis is less active. Mononuclears are more resistant than neutrophils in strong solutions. PAN increased by 11-16% in hypotonic solutions. Strong glycerin solutions reduce PAN less than glucose which stimulates the digestive activity. The results can be of use in specific leukolysis tests to diagnose drug allergy.     

Cytolytic Plasma Factor in Experimental Coccidioidomycosis

Peripheral blood leukocytes from guinea pigs infected with Coccidioides immitis 5 weeks previously were lysed significantly when incubated at 37 C for 3.5 hr with a concentrated C. immitis culture filtrate, but not with a concentrated Aspergillus fumigatus or Blastomyces dermatitidis culture filtrate. Mononuclear leukocytes and presumably granulocytes were both lysed. Characterization of the factor responsible for this leukocytolysis reaction revealed that it was contained in plasma and serum but not in leukocytes from infected guinea pigs. It was complement-dependent, active after heating at 56 C, and stable after storage at -20 C for as long as 14 months.     

Circadian clock functioning is linked to acute stress reactivity in rats

At least two major physiological systems are involved in the adaptation of the organism to environmental challenges: the circadian system and the stress reaction. This study addressed the possibility that interindividual differences in stress sensitivity and in the functioning of the circadian system are related. At 2 months of age, corticosterone secretion in response to a 20-min restraint stress was assessed in 9 Sprague-Dawley rats for which running wheel activity was recorded as a rhythmic behavioral marker of the circadian clock. Two weeks later, the adaptive response of the circadian system to an abrupt shift in the light:dark (LD) cycle was assessed in those rats using a jet-lag paradigm. Finally, after resynchronization to the new LD cycle, rats were transferred to constant darkness to assess the free-running period of their circadian rhythm of running-wheel activity. Results indicate that stress-induced corticosterone secretion was (1) positively correlated with the number of days to resynchronize the circadian activity rhythm to the new LD cycle, and with the value of its free-running period, and (2) negatively correlated with the intensity of daily locomotor activity. Those data, emphasizing the interactions between the stress response of an organism and the functioning of its circadian system, could explain interindividual differences in humans' susceptibility to shift work or other circadian-related disorders.     

Autonomic support of the systemic response under conditions of operator visual-stress activities

The parameters of functioning of muscular, cardiac-respiratory, vegetative and other systems in the organism of healthy persons engaged in the work connected with visual strength have been studied. The optimal limits of system response are determined and thus its realization is shown to be provided with the activation of vegetative regulation apparatus. The structure of the relations between the distinguished parameters is maintained even when new level of functioning is established. Initial activation of vegetative mechanisms is a leading factor of the further rearrangements of visual and somatosensory analyzers with the given kind of activity.     

Effect of increased natural radioactivity on bone marrow morphology of Microtus oeconomus pall

It was established that Microtus oeconomus Pall. living in territories with the increased radiation background exhibit focal myeloid hyperplasia in the bone marrow, changes in the maturation indices of erythroid and myeloid elements, increase in number of karyocytes due to the increase in their mitotic activity. It is suggested that activation of vole haemopoiesis is an adaptive reaction of the organism to the effect of the radioecological factor.     

Ivermectin inhibits activation of Kupffer cells induced by lipopolysaccharide toxin]

Lipopolysaccharide-stimulated liver macrophages (Kupffer cells) secrete many physiologically active substances responsible for inflammatory reaction of the organism. The mechanism by which ivermectin, a macrocyclic lactone possessing a broad antiparasitic activity, modulates basic effects elicited by lipopolysaccharide in the primary culture of rat Kupffer cells was studied. It was found that ivermectin in the absence of endotoxin did not affect a functional state of the Kupffer cells. Preincubation of Kupffer cells with ivermectin (1 mM), however, significantly blocked response to the subsequent administration of lipopolysaccharide (1 mg/ml). In particular, secretion of tumor necrosis factor TNF alpha, nitric oxide NO and prostaglandin E2 was suppressed. Also, an LPS-triggered rise in the intracellular concentration of calcium ions was less pronounced. Removal of chloride anions from the extracellular medium completely abolished inhibitory effects of ivermectin. It is suggested that invermectin exerts its action via binding to the glycine-gated chloride receptors/channels of the Kupffer cells, which may reduce toxic reactions manifestations observed under infections caused by Gram-negative bacteria.     

Inhibitory sequences within the B-domain stabilize circulating factor V in an inactive state

Blood coagulation factor V circulates as a procofactor with little or no procoagulant activity. It is activated to factor Va by thrombin following proteolytic removal of a large central B-domain. Although this reaction is well studied, the mechanism by which bond cleavage and B-domain release facilitate the transition to the active cofactor state has not been defined. Here we show that deletion or substitution of specific B-domain sequences drives the expression of procoagulant function without the need for proteolytic processing. Conversion to the constitutively active cofactor state is related, at least in part, to a cluster of amino acids that is highly basic and well conserved across the vertebrate lineage. Our findings demonstrate that discrete sequences in the B-domain serve to stabilize the inactive procofactor state, with proteolysis primarily functioning to remove these inhibitory constraints. These unexpected results provide new insight into the mechanism of factor V activation.     

Nicotinamide–adenine dinucleotide pyrophosphatase in the growing and aging mosquito

1. The disappearance of pyridine nucleotides during incubation with mosquito homogenates proceeds through the hydrolysis of the pyrophosphate linkage of these compounds as demonstrated by the formation of NMN and AMP from NAD(+). This reaction was also demonstrated by the loss in the coenzyme functioning property of NAD(+) (yeast alcohol dehydrogenase reaction) without a concomitant loss in reactivity towards cyanide. Transglycosidase activity was not observed in the mosquito homogenates, and low concentrations of nicotinamide did not inhibit the NAD(+) splitting activity of these homogenates. These observations are all in accord with the presence in these homogenates of a NAD(+) pyrophosphatase rather than a NADase. 2. The NAD(+) pyrophosphatase is destroyed by boiling, is not heat-activated, and has a pH optimum at pH8.75. In addition to NAD(+), other dinucleotides such as NADP(+), the 3-acetylpyridine and thionicotinamide analogues of NAD(+) and the thionicotinamide analogue of NADP(+), function as substrates in the hydrolysis catalysed by the pyrophosphatase. 3. A decrease in the specific activity of NAD(+) pyrophosphatase was observed during larval development, and a barely detectable activity was found in the pupa and adult. 4. Enzyme activity per organism increased in the larva but decreased to a very low value in the pupa and adult. These results indicate that the decrease in specific activity was due to a decrease in enzyme concentration rather than an increase in amounts of protein.     

Linear analogues derived from the first EGF‐like domain of human blood coagulation factor VII: enhanced inhibition of FVIIa/TF complex activity by backbone modification through aspartimide formation

Coagulation factor VII bound to its cofactor tissue factor is the physiological initiator of blood coagulation. The interaction between factor VII and tissue factor involves all four of the structural modules found in factor VII, with the most significant contribution coming from the first EGF‐like domain. In this study, the synthesis and biological activity of several analogues derived from the first EGF‐like domain of FVII comprising the sequence 45–83 are reported on. The six cysteine residues found in the native protein were replaced by Abu. The peptides were isolated from a multicomponent mixture following standard Fmoc solid phase synthesis. Purification and characterisation of the heterogeneous product showed that aspartimide formation was a major side‐reaction, occurring predominantly at the Asp⁴⁶‐Gly⁴⁷ and Asn⁵⁷‐Gly⁵⁸ dipeptides. Although relatively common in peptide synthesis, the extent to which this side‐reaction had taken place was considered surprising. Reported herein are the analytical methods used to isolate and characterise several of the modified products. Also, the inhibitory effect of these peptides on the formation and enzymatic activity of the factor VIIa/tissue factor complex have been compared. Surprisingly, the peptide containing an iso‐Asp residue at position 57 possessed 66‐fold higher inhibitory activity compared with the original target peptide. A possible explanation for this increase in observed activity is presented. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.     

Antagonistic and bacteriocinogenic activity of Meningococci]

Antagonistic and bacteriocinogenic activity was studied in 169 strains of meningococci of various serological groups and with different localization in the human organism at the time of isolation. Bacteriocinogenic activity was revealed in all the meningococcus strains (by delayed antagonism method), and, in addition, antagonistic activity was found in 100 strains. The inhibitory activity was the greatest in meningococci isolated from the cerebrospinal fluid. The data obtained suggest an important inhibitory activity of meningococci, along with their resistance to the antagonistic activity of the nasopharyngeal microorganisms, in the manifestation of pathogenic properties in them.     

The cell theory. Progress in studies on cell-cell communications

Current data confirm the fundamental statement of the cell theory concerning the cell reproduction in a series of generations (omnis cellula e cellula). Cell communities or ensembles integrated by the signaling systems established in prokaryotes and protists and functioning in multicellular organisms including mammals are considered as the structural and functional unit of a multicellular organism. The cell is an elementary unit of life and basis of organism development and functioning. At the same time, the adult organism is not just a totality of cells. Multinucleated cells in some tissues, syncytial structure, and structural-functional units of organs are adaptations for optimal functioning of the multicellular organism and manifestations of cell-cell communications in development and definitive functioning. The cell theory was supplemented and developed by studies on cell-cell communications; however, these studies do not question the main generalizations of the theory.     

Aggressive behavior, its adaptive function and mechanisms of development of psychosomatic disorders and diseases of adaptation

A correlation between physiologic and behavioral responses to emotional stress and agonistic conflict (triad model), as well as ideas of autonomic-humoral support of subsequent activity suggest that motor activity and situational aggressive behavior are essential final stages of stress reaction and, therefore, mechanisms of adaptation. Failure in final the stage of adaptive response causes mobilization changes to be directed against the host organism itself. This phenomenon forms the basis for psychosomatic disorders. Aggression seems to be an adaptive response not only from ethologic, but from physiologic point of view as well. It has some elements of homeostatic control (together with non-homeostatic functions). Homeostatic role of aggression may be in "elimination" of mobilization metabolic changes caused by stress reaction and physical activity by means of expressive emotional response. Aggression as a non-homeostatic factor has an ethologic function.     

Use of an in vitro allergy test for the differential diagnosis of human brucellosis and yersiniosis

The degree of the allergic reorganization in the body of brucellosis and yersiniosis patients was determined by the study of their blood and serum samples in the in vitro allergy test (the direct and indirect leukocytolysis test). The allergy test is highly specific and recommended as a differential diagnostic method in brucellosis and yersiniosis infections.     

Suppression of lymphocyte activation by a factor produced by Mycoplasma arginini.

Mycoplasma arginini, when grown in broth or in cultures of human lymphoblast cell lines, inhibits activation of lymphocytes by allogeneic cells of mitogens. This inhibition can also be produced by cell free media obtained after the growth of this organism. Inhibition is not species specific and inhibits both B and T cell activation in the mouse. The inhibitory factor is required during the first 3 days of the mixed leukocyte culture, but has no effect on the latter phase of this reaction when thymidine uptake is greatest. The factor is stable to treatment at 60 degrees, but not 90 degrees, for 30 min.     

Novel 5-substituted, 2,4-diaminofuro[2,3-d]pyrimidines as multireceptor tyrosine kinase and dihydrofolate reductase inhibitors with antiangiogenic and antitumor activity

Recent evidence suggests that combination therapy of cancer with receptor tyrosine kinase (RTK) inhibitors, which are usually cytostatic, with conventional chemotherapeutic agents, which are usually cytotoxic, provide an improved treatment option. We have designed, synthesized, and evaluated a series of novel 2,4-diamino-5-substituted furo[2,3-d]pyrimidines with RTK and dihydrofolate reductase (DHFR) inhibitory activity in single molecules, as potential cytostatic and cytotoxic agents with antitumor activity. These compounds were synthesized from 2,4-diamino-5-chloromethyl furo[2,3-d]pyrimidine and aryl methyl ketones using the Wittig reaction to afford the C-8-C-9 unsaturated analogs followed by catalytic reduction to the corresponding saturated compounds. The saturated and unsaturated C-8-C-9 bridged compounds were evaluated as inhibitors of vascular endothelial growth factor receptor (VEGFR-2, Flk, KDR), epidermal growth factor receptor, and platelet-derived growth factor receptor-beta (PDGFR-beta). Selected analogs were also evaluated as antiangiogenic agents in the chicken embryo chorioallantoic membrane (CAM) assay. The compounds were also evaluated as inhibitors of human (h) DHFR and Toxoplasma gondii (tg) DHFR. In each evaluation, a known standard compound was used as a comparison. Of the compounds evaluated, compound 32 was as potent as the standard compounds against VEGFR-2 and PDGFR-beta, showing dual inhibitory activity against RTK. This analog was also highly effective in the CAM assay. A second analog 18 also demonstrated dual VEGFR-2 and PDGFR-beta inhibitory activity as well as potent antiangiogenic activity in the CAM assay. Four additional analogs were also effective against PDGFR-beta and in the CAM assay. An unsaturated C-8-C-9 moiety was necessary for RTK inhibitory activity. Compound 32 also showed inhibitory activity against hDHFR and tgDHFR, illustrating the multitarget inhibitory potential of these analogs. The biological activity of these analogs also suggests the necessity of an unsaturated C-8-C-9 bridge for dual RTK and DHFR inhibitory activity. Compounds 18 and 32 were also evaluated in a B16 melanoma mouse model and were found to be more active as antitumor agents than methotrexate. In addition, both 18 and 32 were also active in decreasing lung metastases in a mouse model of B16 melanomas.     

Chlamydia protease-like activity factor (CPAF): characterization of proteolysis activity in vitro and development of a nanomolar affinity CPAF zymogen-derived inhibitor

During infection of epithelial cells, the obligate intracellular pathogen Chlamydia trachomatis secretes the serine protease Chlamydia protease-like activity factor (CPAF) into the host cytosol to regulate a range of host cellular processes through targeted proteolysis. Here we report the development of an in vitro assay for the enzyme and the discovery of a cell-permeable CPAF zymogen-based peptide inhibitor with nanomolar inhibitory affinity. Treating C. trachomatis-infected HeLa cells with this inhibitor prevented CPAF cleavage of the intermediate filament vimentin and led to the loss of vimentin cage surrounding the intracellular vacuole. Because Chlamydia is a genetically intractable organism, this inhibitor may serve as a tool for understanding the role of CPAF in pathogenesis.     

Nuclear calcium-VEGFD signaling controls maintenance of dendrite arborization necessary for memory formation

The role of neuronal dendrites is to receive and process synaptic inputs. The geometry of the dendritic arbor can undergo neuronal activity-dependent changes that may impact the cognitive abilities of the organism. Here we show that vascular endothelial growth factor D (VEGFD), commonly known as an angiogenic mitogen, controls the total length and complexity of dendrites both in cultured hippocampal neurons and in the adult mouse hippocampus. VEGFD expression is dependent upon basal neuronal activity and requires nuclear calcium-calmodulin-dependent protein kinase IV (CaMKIV) signaling. Suppression of VEGFD expression in the mouse hippocampus by RNA interference causes memory impairments. Thus, nuclear calcium-VEGFD signaling mediates the effect of neuronal activity on the maintenance of dendritic arbors in the adult hippocampus and is required for cognitive functioning. These results suggest that caution be employed in the clinical use of blockers of VEGFD signaling for antiangiogenic cancer therapy.     

The effect of gonadectomy on interhemispheric asymmetry in rats

The influence was studied of the gonadectomy in the newborn and mature male and female rats on functional interhemispheric asymmetry of the reaction of avoidance of pain scream of another rat ("emotional resonance"), and motor and investigatory activity in the open field. Consecutive inactivation of the hemispheres was realized by K+ spreading depression. It has been shown that neonatally gonadectomized rats have no interhemispheric asymmetry of the studied reactions. In male rats gonadectomized in mature state, interhemispheric asymmetry of "the emotional resonance" reaction is not significant and in the motor and investigatory activity in the open field, in contrast to intact animals, the right hemisphere is dominant and not the left one. Ovariectomy of mature female rats led to the increase of the dominance of the left hemisphere in the control of "the emotional resonance" and change of the right hemispheric dominance in the control of the motor and investigatory activity in the open field for the left hemispheric one. Gonadectomy of male and female mature rats had an opposite effect on the functioning of the right hemisphere: facilitating in male rats and inhibitory in female ones.