Biomedical subjects

B Au

Publications and source records attributed to B Au.

5 recordsLinked to original sources

PubMed1991

Effect of two feeding formulas on immune responses and mortality in mice challenged with Listeria monocytogenes.

Cell-mediated immunity and natural killer cells play an important role against facultative intracellular organisms. The effect of two commercially available tube feeding formulas used for patients with acute or chronic debilitating and life-threatening illnesses was studied in mice challenged with Listeria monocytogenes. C57BL/6 X DBA/2 F1 hybrid mice were given ad libitum access to one of two formulas or to chow. Sixty mice in each of the feeding groups were challenged with 4.8 X 10(3) organisms intraperitoneally. Mortality was significantly less in animals fed Impact, a formula enriched with arginine, RNA and selected fatty acids. This was associated with reduced number of viable organisms in the spleen on day 7 after challenge. There was no difference in the spleen/body weight index between the different groups. Delayed cutaneous hypersensitivity was slightly higher in the Impact group but this was not statistically significant. Natural killer cell activity was significantly higher in the Impact group compared with the other two feeding regimens. These observations suggest that selective manipulation of the composition of tube feeding formulas may have a significant impact on immune responses and on morbidity and mortality following infectious challenge.

Animal Feed↗

PubMed1986

Immunopathology of chronic cadmium administration in mice.

Young male mice were given drinking water containing 50 ppm cadmium (Cd) for 3 weeks, and were killed 0, 3 and 6 weeks after the cessation of treatment. At 0 weeks, suppression in the number of splenic plaque-forming cells in response to sheep red blood cell immunization was noted 5 days after antigen injection, but not 7 days after injection. Plasma IgG concentration and thymic factor activity were unaffected at 0 weeks. The number of circulating lymphocytes tended to be less in the Cd-treated mice at all times. Cd treatment had no effect upon liver and kidney weights, and upon the weights and the lymphocyte contents of the thymus and spleen at any of the observation times. Employing immunofluorescence with anti-mouse IgG and C3, no evidence of an autoimmune response was found in the kidney of the treated mice at 0 and 3 weeks. Mitochondrial abnormalities in the renal proximal tubule cells were noted at 0 weeks in the Cd-treated mice. The Cd concentrations of the liver and kidneys remained high at all observation times. The results suggest that a modest dose of Cd produces some depression of the immune system, and the biological half-life of Cd is long.

Animals↗

PubMed1976

Polymorphonuclear leucocyte function in hypothyroidism.

The quantitative nitroblue-tetrazolium test demonstrated that polymorphonuclear leucocytes from patients with hypothyroidism reduced the dye less well than leucocytes from euthyroid persons. The ability of these cells to ingest and kill staphylococci were unimpaired. The abnormality of the nitroblue-tetrazolium test in hypothyroid patients was corrected after their treatment with thyroxine.

Humans↗

PubMedDate not supplied

Iron status, immune response and susceptibility to infection.

Nutritional factors can modulate immune responses. The concentration of iron, amongst other nutrients, influences host defence mechanisms. In experimentally induced iron deficiency in animals, morbidity and mortality on bacterial challenge are increased several-fold. Cell-mediated immunity and intra-cellular bacterial killing by polymorphonuclear leucocytes are impaired in iron-deficient individuals. This impairment is likely to be mediated by the effect of iron lack on cell proliferation, DNA synthesis and activity of iron-containing and iron-dependent enzymes involved in killing and elimination of microbes. Conversely, the availability of the free iron is a critical determinant for bacterial multiplication. It is not surprising then that epidemiological and clinical data on the frequency of infections--bacterial, fungal and others--in iron-deficient, iron-overloaded and healthy groups differ so widely. Vulnerability to infection based on the individual's iron status must be the net result of the effect of iron, or the lack of it, on microbial growth on the one hand and on immunocompetence of the host on the other. The key to keeping these interactions within physiological bounds is 'optimal iron nutrition'.

Anemia, Hypochromic↗

PubMedDate not supplied

Enriched feeding formula and immune responses and outcome after Listeria monocytogenes challenge in mice.

Immunocompromised malnourished patients are at high risk of developing serious opportunistic infection. This study examined the effect of feeding a special nutrient-enriched formula (Immun-Aid) on immune responses and mortality in mice challenged with Listeria monocytogenes. Two protocols were followed. In the first protocol, the animals were challenged with microorganisms when the experimental formula was introduced as the sole source of their nutrition. There was no significant effect on total T-lymphocyte number, but the proportion of helper T cells increased by day 7, resulting in a higher helper/suppressor (H/S) T lymphocyte ratio as well. Response to the mitogen phytohemagglutinin (PHA) was slightly higher on day 3 but came down and was comparable with that of control animals by day 7. Natural killer cell activity was slightly higher on day 7. Other immunologic parameters were unchanged. There was no significant difference in mortality between the two groups. In the second protocol, the animals were fed the experimental diet for 7 days before the infectious challenge. There was a slight increase in the total number of T lymphocytes on day 7. The numbers of helper and suppressor T lymphocytes were unchanged, but H/S was slightly higher on day 3 in the experimental group. Response to PHA was again higher on day 3 but plateaued on day 7. Natural killer cell activity was not altered. Mortality after infectious challenge was slightly but significantly decreased in the group of animals fed the enriched special formula. These results indicate a slight enhancement of selected parameters of immunity in mice fed the specially enriched formula and show that prior feeding with this formula for several days may partly protect against infectious challenge, resulting in reduced mortality.

Animals↗