Different histopathological response to Arenovirus infection in thymectomized mice

Summary In this paper the survival and the histopathology of normal and thymectomized mice infected with some Arenoviruses is reported.Normal newborn mice infected intracerebrally with Junín, Machupo, Tacaribe and Amaparí virus showed similar histopathological changes in the central nervous system characterized by choroiditis, glial hyperplasia, vasculitis and perivasculitis with infiltration of lymphocytic cells.In thymectomized mice infected with Junín, Machupo and Tacaribe virus, there was no evidence of disease, survival reached almost 100% and no pathological alterations were observed in the brain.In contrast, thymectomized mice infected with Amaparí virus showed the same percentage of mortality and similar histopathological changes as non-thymectomized animals.This research was supported by Grant N 4908/71 from Consejo National de Investigaciones Cientificas y Técnicas, República Argentina, and by funds from Comisión Coordinadora para el estudio y lucha contra la Fiebre Hemorrágica Argentina de la Subseeretaría de Salud Pública, República Argentina.Chairman Department of Pathology, National Academy of Medicine, República Argentina.Members of Research Career from the Consejo Nacional de Investigaciones Cientificas y Técnicas, República Argentina.     

Increased phagocytic capacity of the blood,but decreased phagocytic activity per individual circulating neutrophil after an ultradistance run

The effect of a long strenuous endurance exercise on the phagocytic function of neutrophils was examined. 9 athletes [7 males, 2 females, age: 36–68 years, body mass: 64 (SD 10) kg, height: 175 (SD 10) cm] completed a competetive 100 km run in 8:07 (median value; range: 7:29–9:50 hours). In a whole blood assay the phagocytosis of opsonized E. coli, the receptor density of the Fc receptor 3 (CD16) and the complement receptor 3 (CD11b, direct immunofluorescence) of neutrophils were measured on a per cell basis by flow cytometry before and up to 3 hours after the race. The phagocytic rate (percentage of neutrophils incorporating bacteria) was unchanged after exercise, whereas the phagocytic activity (number of incorporated bacteria per cell) was significantly reduced by –34 (SD 8) % (Wilcoxon test, P<0.001). The total phagocytic capacity of the blood increased 2-3fold post exercise. The surface antigen expressions of CD11b and CD16 were unaffected by the ultradistance run. The results indicate either a reduced phagocytic function of neutrophils on a single cell basis or the mobilization of neutrophils of the marginal pool with a lower phagocytic activity. However, after a long endurance exercise the phagocytotic capacity of the blood was enhanced due to increased cell concentrations.     

Mutagenicity,antioxidant potential,and antimutagenic activity against hydrogen peroxide of cashew (Anacardium occidentale) apple juice and cajuina

Fresh and processed cashew (Anacardium occidentale) apple juice (CAJ) are among the most popular drinks in Brazil. Besides their nutritional benefits, these juices have antibacterial and antitumor potential. The chemical constituents of both the fresh juice and the processed juice (cajuina) were analyzed and characterized as complex mixtures containing high concentrations of vitamin C, various carotenoids, phenolic compounds, and metals. In the present study, these beverages exhibited direct and rat liver S9-mediated mutagenicity in the Salmonella/microsome assay with strains TA97a, TA98, and TA100, which detect frameshifts and base pair substitution. No mutagenicity was observed with strain TA102, which detects oxidative and alkylating mutagens and active forms of oxygen. Both CAJ and cajuina showed antioxidant activity as determined by a total radical-trapping potential assay. To test whether this antioxidant potential might result in antimutagenesis, we used a variation of the Salmonella/microsome assay that included pre-, co-, and posttreatment of hydrogen peroxide-exposed Salmonella typhimurium strain TA102 with the juices. CAJ and cajuina protected strain TA102 against mutation by oxidative damage in co- and posttreatments. The antimutagenic effects during cotreatment with hydrogen peroxide may be due to scavenging free radicals and complexing extracellular mutagenic compounds. The protective effects in posttreatment may be due to stimulation of repair and/or reversion of DNA damage. The results indicate that CAJ and cajuina have mutagenic, radical-trapping, antimutagenic, and comutagenic activity and that these properties can be related to the chemical constituents of the juices.     

Mobilization and oxidative burst of neutrophils are influenced by carbohydrate supplementation during prolonged cycling in humans

Prolonged, strenuous exercise may lead to suppressive effects on the immune system, which might be responsible for a greater susceptibility to opportunistic infections. The aim of this study was to examine the influence of carbohydrate substitution (CHS) during prolonged, strenuous exercise on neutrophil granulocytes and their oxidative burst (intracellular oxidation of dihydrorhodamine₁₂₃ to rhodamine₁₂₃ after induction by formylized 1-methionyl-1-leucyl-1-phenylalanin) using flow cytometry. In three trials different concentrations of CHS (placebo compared to 6% and 12% CHS; 50 ml·kg^–1) were given randomly to 14 endurance trained cyclists [mean (SD) age 25 (5) years, maximal oxygen uptake 67 (6) ml·min^–1·kg^–1] cycling for 4 h in a steady state at 70% of their individual anaerobic threshold. Blood samples were taken before, immediately after cessation, 1 h and 19 h after exercise. A significant rise in neutrophil counts was observed immediately after cessation and 1 h after exercise with a return to normal rest values 19 h after exercise for all three conditions (P<0.001). The relative proportions of rhodamine₁₂₃+ neutrophils were significantly diminished in all three conditions 1 h after exercise (P<0.01), while the mean fluorescence intensity was lowest in the placebo trial and differed significantly to the 12% CHS trial (P=0.024) and almost significantly to the 6% CHS trial (P=0.052). In conclusion, these data suggest a beneficial effect of CHS on the neutrophil oxidative burst and a possible attenuation of the susceptibility to infections, presumably due to the reduction of metabolic stress in prolonged, strenuous exercise. Electronic Publication     

Comparative pharmacokinetics of ciprofloxacin,ofloxacin and pefloxacin in human aqueous humour

Eighty-five patients undergoing cataract surgery were given for prophylaxis of intraocular infection two intravenous doses each of 200 mg, 300 mg or 400 mg ciprofloxacin (35 patients), 400 mg or 800 mg pefloxacin (30 patients), or 400 mg ofloxacin (20 patients). Ciprofloxacin levels in aqueous humour ranged from 0.02 to 0.50 µg/ml, pefloxacin levels from 1.04 to 7.80 µg/ml, and ofloxacin levels from 0.44 to 2.27 µg/ml with ratios of aqueous humour to serum levels ranging from 3.8 % to 25 %, 21 % to 48.1 % and 44 % to 88.4 %, respectively. It is concluded that the quinolones studied might be suitable for surgical prophylaxis or treatment of anterior chamber infections due toEnterobacteriaceae, while ciprofloxacin at high doses is preferable forPseudomonas aeruginosa infections.     

Role of Intestinal Epithelial Cells in Immune Effects Mediated by Gram-Positive Probiotic Bacteria: Involvement of Toll-Like Receptors

The mechanisms by which probiotic bacteria exert their effects on the immune system are not completely understood, but the epithelium may be a crucial player in the orchestration of the effects induced. In a previous work, we observed that some orally administered strains of lactic acid bacteria (LAB) increased the number of immunoglobulin A (IgA)-producing cells in the small intestine without a concomitant increase in the CD4⁺ T-cell population, indicating that some LAB strains induce clonal expansion only of B cells triggered to produce IgA. The present work aimed to study the cytokines induced by the interaction of probiotic LAB with murine intestinal epithelial cells (IEC) in healthy animals. We focused our investigation mainly on the secretion of interleukin 6 (IL-6) necessary for the clonal expansion of B cells previously observed with probiotic bacteria. The role of Toll-like receptors (TLRs) in such interaction was also addressed. The cytokines released by primary cultures of IEC in animals fed with Lactobacillus casei CRL 431 or Lactobacillus helveticus R389 were determined. Cytokines were also determined in the supernatants of primary cultures of IEC of unfed animals challenged with different concentrations of viable or nonviable lactobacilli and Escherichia coli, previously blocked or not with anti-TLR2 and anti-TLR4. We concluded that the small intestine is the place where a major distinction would occur between probiotic LAB and pathogens. This distinction comprises the type of cytokines released and the magnitude of the response, cutting across the line that separates IL-6 necessary for B-cell differentiation, which was the case with probiotic lactobacilli, from inflammatory levels of IL-6 for pathogens.     

Bone-specific antibodies in sera from patients with celiac disease: characterization and implications in osteoporosis

Osteopenia and osteoporosis are well-known complications detected in celiac disease patients with still obscure pathogenesis. In the present study we investigated the presence of circulating anti-bone autoantibodies in patients with celiac disease and explored their role in the associated bone disease. We evaluated serum samples from 33 patients at the time of diagnosis and from 20 of them after treatment. Sera from patients with inflammatory bowel disease (n = 9), nonceliac osteoporotic (n = 18), and healthy individuals (n = 10) were used as controls. The presence of IgA specific anti-bone antibodies was first investigated using indirect immunofluorescence on cryosections of fetal rat tibia (20-day pregnancy). Furthermore, samples were homogenized and total tissue extracts were subjected to Western blot analysis to confirm immunoreactivity. At diagnosis, sera from 51.5% (17/33) of celiac patients had antibodies that recognized antigenic structures in chondrocytes and the extracellular matrix along mature cartilage, bone interface, and perichondrium of fetal rat bone. Among controls, only two osteoporotic patients showed very low titles of anti-bone autoantibodies. The immunostaining was localized in areas where an active mineralization process occurred and was similar to the distribution of the native bone tissue transglutaminase. The frequency of patients with positive baseline titers of anti-bone antibodies diminished significantly after treatment (P = 0.048). Western blot assays confirmed the presence of autoantibodies in sera from patients with a positive immunofluorescence staining. Autoantibodies recognized a major protein band on tissue extracts with a molecular weight of 77–80 kDa, which could be displaced when sera were preadsorbed with human recombinant tissue transglutaminase. We provide original evidence that patients with celiac disease have IgA-type circulating autoantibodies against intra- and extracellular structures of fetal rat tibia. Our findings suggest that these antibodies recognize bone tissue transglutaminase as the autoantigen, and based on the localization of the immunoreactivity we speculate that they might have an active role in the pathophysiology of celiac disease-associated bone complications.     

Membrane ionic currents and properties of freshly dissociated rat brainstem neurons

It is well known that neuronal firing properties are determined by synaptic inputs and inherent membrane functions such as specific ionic currents. To characterize the ionic currents of brainstem cardio-respiratory neurons, cells from the hypoglossal (XII) nucleus and the dorsal motor nucleus of the vagus (DMX) were freshly dissociated and membrane ionic currents were studied under whole-cell voltage and current clamp. Both of these neurons showed a TTX-sensitive Na⁺ current with a much larger current density in XII than DMX neurons. This Na⁺ current had two (fast and slow) distinct inactivation decay components. The ratio of the magnitudes of the fast to slow component was roughly two-fold greater in DMX than in XII cells. Both DMX and XII neurons also showed a high voltage-activated Ca²⁺ current, but this current density was significantly greater (three-fold) in DMX than XII neurons. A relatively small amount of low-voltage activated Ca²⁺ current was also observed in DMX neurons, but not in the majority of XII cells. A transient and a sustained outward current components were observed in DMX cells, but only sustained currents were present in XII neurons. These outward currents had a reversal potential of about − 70 mV with 3 mM external K⁺ and −30 mV with 25 mM K⁺, and substitution of K⁺ with cesium and tetraethylammonium suppressed more than 90% the outward currents, indicating that most outward currents were carried by K⁺. The transient outward current consisted of two components with onesensitive to 4-aminopyridine and the other to intracellular Ca²⁺. In XII neurons, BRL 38227 (lemakalim), an ATP-sensitive K⁺ (K_ATP) channel activator, increased the sustained K⁺ currents by 10% of control, and glibenclamide, a K_ATP channel blocker, decreased the sustained K⁺ currents by 20%. Evidence for the presence of an inward rectifier K⁺ current was also obtained from both XII and DMX neurons. These results on XII and DMX neurons indicate that (1) the methods used to dissociate neurons provide a useful means to overcome voltage clamp technical difficulties; (2) ion channel characteristics such as density and biophysical properties of DMX neurons are very different from those of XII neurons; and (3) several newly discovered membrane ionic currents are present in these cells.