Decreased levels of ascorbic acid in lung following exposure to ozone

Mice were exposed to concentrations of 20, 40 and 200 ppm ozone in air for 30 min. Ozone exposure decreased lung ascorbic acid levels and increased lung weight by up to 50% in a dose related manner. On incubation in Krebsphosphate solution, lung slices from mice exposed to 200 ppm ozone released a smaller fraction of their content of ascorbic acid into the medium than did lung slices from control mice, suggesting that there was a preferential loss of extracellular ascorbic acid during ozone exposure. These results are consistent with the proposed function of ascorbic acid as an extracellular antioxidant in lungs.     

Assessment of cervicovaginal cytokine levels following exposure to microbicide Nisin gel in rabbits

Topical microbicides is an emerging female controlled strategy for preventing the acquisition and transmission of STIs/HIV infections. Since they are intended for repeated vaginal and/or rectal use it is essential to validate their safety. Nisin, a naturally occurring contraceptive antimicrobial peptide (AMP) is currently the focus of clinical trials. The present in vitro vaginal tissue explants culture studies revealed that Nisin did not effect vaginal cell viability analyzed at 15, 30, 45 and 60min following treatment with different concentrations of Nisin gel prepared in 1% polycarbophil gel (30.3, 60.6, 121.2, 242.4 and 484.8 microM/g tissue) and SDS (0.35, 0.70, 1.4, 2.8 and 5.6 microM/g tissue) gels compared to placebo gel treated groups. The levels of various pro-inflammatory (IL-6, IL-8 and TNF-alpha,) and immuno-regulatory cytokines (IL-10 and GM-CSF) in the explant culture supernatants of the Nisin treated cells were unaffected. Repeated intravaginal application of high dose of Nisin gel (15,150 microM/day/14 days) on cervicovaginal epithelium was evaluated in rabbits and the results were compared with SDS treated (56 microM) and 1% polycarbophil gel (placebo) groups. We examined vaginal cell morphology, structural integrity of vaginal epithelium and local production of cytokines (PICs) in the cervicovaginal lavage (CVL) of Nisin treated animals and compared with placebo and SDS treated groups. The results demonstrated no treatment related abnormalities either in the vaginal cell morphology or structural abnormalities in the mucosal epithelium. There was no change in the cytokine levels in cervicovaginal lavage (CVL) compared to SDS gel treated animals indicating Nisin gel did not induce irritation and/or inflammation in the vaginal epithelium. CVL cytokine levels were in accordance with immunohistochemical (IHC) localization of cytokines and flow cytometric evaluation of CD45 immune cell population in cervicovaginal epithelium. The levels of cytokines in the CVLs appear to be sensitive indicators in identifying and/or screening out suitable candidate microbicides before they enter phase-1 trials. In conclusion, the lack of vaginal toxicity of Nisin gel means that it has clinical potential as a safe, prophylactic contraceptive in addition to its antimicrobial activities to curb sexual transmission of HIV in human.     

Tissue distribution of astaxanthin in rats following exposure to graded levels in the feed

To determine the organ distribution of high doses of astaxanthin in rats (Rattus norvegicus) after oral application, a two week experiment was conducted, observing time (one and two weeks) and dose response (0.3, 1 and 3% of the feed). Low astaxanthin concentrations were detected in the viscera, distributed in a wide range, and not increasing from 7th to 14th day. This indicates that there was rapid elimination or catabolism and no profound long term storage. Liver concentration was unexpectedly low while the highest concentrations were found in spleen, kidneys and adrenals. The main site of astaxanthin accumulation, indeed, was the hairless skin of the tail, this was associated with red coloration (+a(*) in the CIELAB tristimulus). Because the discoloration was not observed until the second week and the variability in the astaxanthin concentrations was lower, it seems that the accumulation and elimination in skin is slower, compared to other tissues. Potential adverse effects such as lesions in the kidneys of three animals and a slight (n.s.) change in the leucogram were also noted. Furthermore, astaxanthin accumulated in the eyes in the same magnitude as it is known for canthaxanthin in the eyes of rats.     

Rapid changes in levels of mineral nutrients in root-tip cells following short-term exposure to aluminium

We investigated the rapid modification of plasma membrane and changes in mineral nutrients in root-tip cells of Al-tolerant rice and Al-sensitive barley following short-term exposure to Al (20 M Al, 1 h). The plasma membrane of the barley cells was significantly permeabilized when re-elongated in an Al-free Ca solution following a 1-h pre-treatment with Al, while that of rice cells was not affected at all. The elemental distribution and concentration in a 2-mm portion of the root apex were determined by electron probe X-ray microanalysis. Al was localized primarily to the epidermis and outer cortex cells in both species, and was much more abundant in barley than in rice. Al increased and decreased remarkably the intracellular K concentration in whole root-tip cells of rice and barley, respectively. In barley, the decrease in the concentration of Ca coincided with the accumulation of Al. Conversely, the intracellular concentration of P in the surface layers of root-tip cells increased with the accumulation of Al. The distribution and concentration of Ca and P in rice did not change after 1-h treatment with Al. These results suggest that the rapid modification of the plasma membrane of root-tip cells induced by Al affects the nutritional homeostasis in the cells.     

Increased levels of markers of microbial exposure in homes with indoor storage of organic household waste

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold beta(1-->3)-glucans, and fungal extracellular polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4. 6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.     

Blood oxygen levels and acid-base status following air exposure in an air-breathing fish, Channa argus: the role of air ventilation

1. Acute air exposure of an air-breathing fish Channa argus immediately induced hypercapnic acidemia while total CO2 content of blood remained unchanged. Upon reimmersion, paco2 and pHa quickly restored to pre-exposure levels followed by gradual rise of [HCO-3]. 2. Artificial air ventilation of air-exposed fish restored acid-base status and greatly depressed voluntary air ventilatory movements. We conclude that the major cause of acid-base disturbances occurring during air exposure is the reduced air convection.     

Survivability and long-term stress reactivity levels following repeated exposure to nuclear magnetic resonance imaging procedures in rats

The effect of exposure to the magnetic and radio-frequency fields associated with Nuclear Magnetic Resonance Imaging (MRI) on survivability and long-term stress reactivity levels was examined in male rats. Rats in the experimental condition were exposed to MRI for 22.5 minutes for five successive days (Expt. 1) or 23.3 minutes for twenty-one successive days (Expt. 2). Sham field exposed animals received the identical treatment as the exposed animals except that the magnetic and radio-frequency fields were absent. Control rats were also maintained. Thirteen to twenty-two months after the exposure procedure the remaining rats were sacrificed and their whole body, spleen, heart, thymus, and adrenal weights were recorded. Blood samples were taken for measurements of red and white blood cell counts, hemoglobin content, as well as adrenocorticotrophin and corticosterone levels. The results fail to provide any evidence for changes in survivability and long-term stress reactivity levels in rats exposed to MRI and thus give no grounds to challenge the view that MRI is a safe diagnostic procedure.     

Increased prothrombin time and metabolic changes with high serum aluminum levels following long-term exposure to Bayer-process alumina

Serum aluminum levels twice to three times those in controls were found in 30 of 36 workers in a factory in an atmosphere of alumina dust. Inorganic phosphate and total alkaline phosphatase levels were within normal range, with no clinical evidence of phosphate depletion syndrome. Serum intestinal alkaline phosphatase, acid phosphatase and adenosine triphosphate levels were significantly reduced in the group with high levels of aluminum. The finding that the mean prothrombin time was significantly prolonged is of particular interest with respect to beneficial antithrombogenic effect.     

Immunity of sheep to homologous challenge with dog-borne Sarcocystis species following varying levels of prior exposure

Ford G. E. 1985. Immunity of sheep to homologous challenge with dog-borne Sarcocystis species following varying levels of prior exposure. International Journal for Parasitology15: 629–634. Grazing sheep in which sarcocysts develop (sarcosporidiosis) survive the pre-cyst stages of the parasite infection which cause pathophysiological changes (sarcocystosis). A peak temperature rise occurs at 3–4 weeks post-infection in experimental animals. A maximum fall in packed cell volume occurs at 5–6 weeks post-infection. Groups of sheep maintained specific pathogen free were experimentally infected with sporocysts of dog-origin to determine the dose level required for protection or resistance, and 13 weeks later challenged with a pathogenic dose of 50,000 sporocysts. Prior exposure levels (PEL) were used of nil, 5, 50, 500 and 5000 sporocysts. All prior infections elicited an antibody response to a complement fixation test in all sheep. A peak antibody level was detected within 2 weeks of challenge, with a higher titre for all previously exposed groups than for the nil PEL controls. Resistance of the sheep to the challenge dose, based on reduction of counts of parasites developing (sarcosporidiosis), was shown by significantly lower counts for the 50 PEL group (85%), as well as for the 500 (92%) and 5000 PEL (98%) groups. The 5 PEL group was not resistant. The protection of sheep, based on reduction of the above pathophysiological changes (sarcocystosis), was highly correlated with the level of prior exposure (r = ?0.80, P < 0.001). The changes in body temperature and packed cell volume were significantly less in groups with 500 and 5000 PEL than with nil and 5 PEL. The 50 PEL group was intermediate.