The pathogenetic bases for chemotherapy in an experimental Salmonella infection]

The effect of etiotropic (polymyxin and adriblastin) and pathogenetic (levamisole and vitamin E) chemotherapy on lipid peroxidation (LPO), phagocyte functional activity and the process and outcomes of Salmonella infection was studied in rabbits. It was shown that development of salmonellosis was accompanied by activation of LPO which was phase-by-phase. There was synchronism in changing of LPO and neutrophilic phagocytic activity. Adriblastin and levamisole stimulated LPO and increased the neutrophilic phagocytic activity. Vitamin E inhibited LPO and had an unfavourable effect on the process and outcomes of the infection. The problem in differential use of the chemotherapeutic drugs with an account of their modulating effect on LPO is discussed.     

Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K _p indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (ΔBRS with ΔMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with ΔMPPG; r _s=−0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect. An erratum to this article can be found at     

Verapamil protective effect on natural and artificial magnetic field cardiovascular impact

Previously we found an opposite effect of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. A 0.35 T SMF increased baroreflex sensitivity (BRS), whereas GMF disturbance decreased BRS. Here, we investigated interrelated impacts on arterial baroreceptors of 0.35 T SMF, generated by Nd(2)-Fe(14)-B alloy magnets, GMF, and verapamil, a Ca(2+) channel blocking agent. We measured BRS in rabbits before and after local SMF exposure of sinocarotid baroreceptors or after simultaneous SMF and verapamil application, in conjunction with geomagnetic disturbance during actual experimental run (determined by K-index) and geomagnetic disturbance over the preceding 24 h of each experiment (A(k)-index). BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate, expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. Prior to verapamil and/or SMF application we found a significant positive correlation of K-index with MAP (t = 2.39, P =.021, n = 44), but negative with BRS (t = -4.60, P =.0003, n = 44), and found a negative correlation of A(k)-index with BRS (t = -2.7, P = 0.01, n = 44). SMF induced an increase in BRS (0.79 +/- 0.1 vs. 1.15 +/- 0.1 bpm%/mmHg%, initial value vs. SMF exposure, P <.0002, n = 26). Verapamil infusion blocked the SMF and GMF effect on BRS, indicating Ca(2+) channels as a possible site of both fields' impact. SMF and GMF probably affect baroreceptor sensory transduction, modulating baroreceptor membranes' Ca(2+) channel permeability.     

Optimization of static magnetic field parameters improves analgesic effect in mice

The present study deals with the analgesic effect induced by static magnetic fields (SMF) in mice exposed to the field with their whole body. It discusses how the effect depends on the distribution of the magnetic field, that is, on the specification and arrangement of the applied individual permanent magnets. A critical analysis of different magnet arrangements is given. As a result the authors propose a magnet arrangement recipe that achieves an analgesic effect of over 80% in the writhing test. This is a widely accepted screening method for animal pain and predictor of human experimental results. As a non-drug, non-invasive, non-contact, non-pain, non-addictive method for analgesia with immediate and long-lasting effect based on the stimulus of the endogenous opioid network, the SMF treatment may attract the attention of medical doctors, nurses, magnet therapists, veterinarians, physiotherapists, masseurs, and fitness trainers among others.     

Cross-protection against Salmonella enteritidis infection in mice

Mice were vaccinated with six strains of Salmonella and two strains of Escherichia coli, as well as with Pseudomonas aeruginosa, Proteus vulgaris, and Serratia marcescens. The amount of in vivo growth of each organism was followed by viable counting techniques on organ homogenates. The vaccinated mice, along with unvaccinated controls, were challenged intravenously with 1,000 ld(50) of a streptomycin-resistant strain of Salmonella enteritidis. The ability of the vaccine to protect the mice against virulent challenge correlated with the ability of the strain to establish a persisting population in the liver and spleen. Enumeration of the liver and spleen populations in the challenged mice revealed that extensive growth of S. enteritidis occurred in animals which showed "protection," as assessed by progressive mortality data. No evidence was obtained for a major role of humoral factors in the cross-protection against intravenous S. enteritidis challenge.     

The effect of alternating electric field of industrial frequency on testicles of white mice]

Under the chronic influence of the alternating electric field (intensity 40 kV/m, frequency 50 Hz) the oppression of spermatogenesis was observed in the ontogenesis process of testicles of white mice. It was a result of disturbances in spermatogonia and spermatids. Investigation of the stability of mice testicles in different age groups (juvenile, puberal and old) has shown that the 1st and the 3d groups are the most sensitive ones.     

The permeability of SPION over an artificial three-layer membrane is enhanced by external magnetic field

Background  

Sensorineural hearing loss, a subset of all clinical hearing loss, may be correctable through the use of gene therapy. We are testing a delivery system of therapeutics through a 3 cell-layer round window membrane model (RWM model) that may provide an entry of drugs or genes to the inner ear. We designed an in vitro RWM model similar to the RWM (will be referred to throughout the paper as RWM model) to determine the feasibility of using superparamagnetic iron oxide (Fe₃O₄) nanoparticles (SPION) for targeted delivery of therapeutics to the inner ear.     

The effect of strong static magnetic field on lymphocytes

We investigated whether static electromagnetic fields (EMFs) at a flux density of 4.75 T, generated by an NMR apparatus (NMRF), could promote movements of Ca2+, cell proliferation, and the eventual production of proinflammatory cytokines in human peripheral blood mononuclear cells (PBMC) as well as in Jurkat cells, after exposure to the field for 1 h. The same study was also performed after activation of cells with 5 mg/ml phytohaemagglutinin (PHA). Our results clearly demonstrate that static NMRF exposure has neither proliferative, nor activating, nor proinflammatory effects on both normal and PHA activated PBMC. Moreover, the concentration of interleukin-1beta, interleukin-2, interleukin-6, interferon, and tumour necrosis factor alpha (TNFalpha) remained unvaried in exposed cells. Exposure of Jurkat cells statistically decreased the proliferation and the proliferation indexes, which 24 and 48 h after exposure were 0.7 +/- 0.29 and 0.87 +/- 0.12, respectively. Moreover, in Jurkat cells the [Ca2+]i was higher than in PBMC and was reduced significantly to about one half after exposure. This is consistent with the decrease of proliferation and with the low levels of IL-2 measured. On the whole, our data suggest that NMRF exposure failed to affect the physiologic behaviour of normal lymphomonocytes. Instead in Jurkat cells, by changing the properties of cell membranes, NMRF can influence Ca2+ transport processes, and hence Ca2+ homeostasis with improvement of proliferation.     

Cross-protection against Salmonella enteritidis infection in mice.

Mice were immunized subcutaneously with live vaccines and live vaccines with complete adjuvant incorporating Salmonella enteritidis Se 795, Salmonella typhi-murium M206, Salmonella gallinarum 9R or Salmonella pullorum Sp223. They were challenged along with unvaccinated controls with 100 LD50 of virulent S. enteritidis 5694 SMR subcutaneously on the 21st day post-vaccination. The humoral immune response was studied by assessing the sequential level of agglutinins, complete and incomplete somatic antibodies, opsonophagocytic antibodies, cytophilic antibodies and bactericidal antibodies before and after challenge. The level of these antibodies and the protection afforded by the particular vaccine is correlated and the possible involvement of a humoral mechanism is discussed.     

静态强磁场对枯草芽胞杆菌的影响研究

目的:研究静态强磁场下微生物的生物学效应.方法:以超导磁体产生的静态强磁场为基础,枯草芽孢杆菌为模式生物,通过测定生长曲线、芽胞生成率、蛋白酶表达量、蛋白酶活力等研究静态强磁场条件下微生物性状的变化.结果:强磁场可以影响枯草芽胞杆菌的芽胞形成速率,抑制营养体的死亡;测定菌体生长过程中蛋白酶的含量以及碱性蛋白酶和中性蛋白酶的酶活力,发现磁场处理前后蛋白酶的含量没有发生显著性变化,处理组碱性蛋白酶的酶活力明显高于对照组,而中性蛋白酶酶活力则低于对照组.结论:强磁场可以延长枯草芽孢杆菌的世代周期,降低菌体死亡率,对细菌酶活性的影响因酶的种类不同而异.     

The effect of an electromagnetic field on the indices of conditioned reflex activities in rats]

The formation of defensive conditional reflexes in rats exposed to 10 cm electromagnetic field of different power densities during 4-months-long experiment has been studied. Stability of conditional reflectory reactions for the whole period of exposure is shown. The after-exposure period is characterized by the prevalence of excitatory processes.     

PIR-B-deficient mice are susceptible to Salmonella infection

Paired Ig-like receptors of activating (PIR-A) and inhibitory (PIR-B) isoforms are expressed by many hematopoietic cells, including B lymphocytes and myeloid cells. To determine the functional roles of PIR-A and PIR-B in primary bacterial infection, PIR-B-deficient (PIR-B(-/-)) and wild-type (WT) control mice were injected i.v. with an attenuated strain of Salmonella enterica Typhimurium (WB335). PIR-B(-/-) mice were found to be more susceptible to Salmonella infection than WT mice, as evidenced by high mortality rate, high bacterial loads in the liver and spleen, and a failure to clear bacteria from the circulation. Although blood levels of major cytokines and Salmonella-specific Abs were mostly comparable in the two groups of mice, distinct patterns of inflammatory lesions were found in their livers at 7-14 days postinfection: diffuse spreading along the sinusoids in PIR-B(-/-) mice vs nodular restricted localization in WT mice. PIR-B(-/-) mice have more inflammatory cells in the liver but fewer B cells and CD8(+) T cells in the spleen than WT mice at 14 days postinfection. PIR-B(-/-) bone marrow-derived macrophages (BMMphi) failed to control intracellular replication of Salmonella in vitro, in part due to inefficient phagosomal oxidant production, when compared with WT BMMphi. PIR-B(-/-) BMMphi also produced more nitrite and TNF-alpha upon exposure to Salmonella than WT BMMphi did. These findings suggest that the disruption of PIR-A and PIR-B balance affects their regulatory roles in host defense to bacterial infection.