Decreased antibody formation in iron-deficient rat pups--effect of iron repletion.

Rats were fat diets containing 6, 12, or 250 ppm iron throughout gestation and lactation. On day 17, pups immunized with sRBC were used to determine antibody synthesis by the Jerne plaque assay. In both iron-deficient groups, antibody formation was decreased by at least 50% compared to controls. For 3 weeks beginning on day 21, iron-deficient pups were fed either a control diet (35 ppm iron) or the same iron-deficient diet as fed to the dam. IgG and IgM formation was only slightly improved in repleted rats and remained significantly below that of rats fed the control diet throughout the experiment. In contrast, 250 ppm iron pups fed an iron-deficient diet postweaning had significantly decreased IgG and IgM production compared to littermates fed a control diet postweaning. Maternal iron deficiency during the critical pre- and postnatal growth periods may result in long-term impairment of humoral immunity that is not corrected by dietary iron repletion after weaning.

A method of assessing the efficacy of hand sanitizers: use of real soil encountered in the food service industry.

In many outbreaks of foodborne illness, the food worker has been implicated as the source of the infection. To decrease the likelihood of cross-contamination, food workers must clean and disinfect their hands frequently. To ensure their effectiveness, hand disinfectants should be tested using rigorous conditions that mimic normal use. Currently, several different methods are used to assess the efficacy of hand disinfectants. However, most of these methods were designed with the health care worker in mind and do not model the specific contamination situations encountered by the food worker. To fill this void, we developed a model that uses soil from fresh meat and a means of quantifying bacteria that is encountered and transferred during food preparation activities. Results of studies using various doses of para-chloro-meta-xylenol and triclosan confirm that the method is reproducible and predictable in measuring the efficacy of sanitizers. Consistent, dose-dependent results were obtained with relatively few subjects. Other studies showed that washing hands with a mild soap and water for 20 s was more effective than applying a 70% alcohol hand sanitizer.

Effect of calcium citrate-malate on skeletal development in young, growing rats.

It has been previously demonstrated that calcium from calcium citrate-malate (CCM), a mixture of calcium, citric acid and malic acid, is better-absorbed than calcium from calcium carbonate (CaCO3) in humans and in rats. It was of interest to determine if this differential in absorption would result in differences in bone development under chronic feeding conditions. The present study was designed to compare CCM with CaCO3 for effects on bone development in weanling female C/D rats fed either CCM or CaCO3 at 0.3 or 0.6% dietary Ca for 4 or 12 wk. There was a nonsignificant trend for rats fed CCM to weigh more and have larger bones than rats fed CaCO3. Histologic evaluation of cortical and trabecular bone revealed normal bone formation in all rats. Trabecular bone was significantly affected by calcium level and source. The 0.3% Ca diets (either source) resulted in reduced trabecular bone volumes in tibias. After 4 wk, rats fed CCM had 23-25% more trabecular bone than rats fed CaCO3. By 12 wk, the difference was even greater; rats fed CCM had 44-47% more trabecular bone than rats fed CaCO3. Dietary calcium source did not affect cortical bone. It is concluded that because of its positive effects on bone, CCM is a more bioavailable calcium source than CaCO3.

Cellular growth in iron-deficient rats: effect of pre- and postweaning iron repletion.

Effects of iron deficiency and repletion pre- and postweaning on cell growth in young rats were studied. Pregnant dams were fed 6 or 250 ppm iron. On d 2 of lactation, half of the dams in each group were fed the opposite diet. On d 17, cell growth in the crossed-over groups was similar to controls showing that cellular development is impaired only when the iron deficiency is present during gestation and lactation. In a second experiment pup littermates of dams fed 6 (D), 12 (M) and 250 (C) ppm iron were weaned to either the same diet as fed to their dams DD, MM or CC; repleted with iron DC, MC; or fed the deficient diet CD until 42 d of age. After dietary iron repletion, cell numbers in thymus (DC and MC) and liver (DC) were greater than those of deficient littermates, but were less than those of controls (CC). Iron repletion postweaning reduced the cardiac hypertrophy (DC vs. DD and MC vs. MM) and increased splenic cell number compared to unrepleted deficient littermates (DC vs. DD). Thus, the severity and reversibility of impaired cellular growth is dependent on the timing and severity of the deficiency and the organ affected.

Cellular growth in iron-deficient rat pups.

Groups of 10 pregnant rats weighing 200-215 g were fed ad libitum diets containing 10, 100, or 250 ppm iron (Fe) throughout gestation and lactation. Litters were adjusted at birth to contain 7 pups, and on day 17 of lactation, dams and pups were sacrificed. Fe status was determined, and tissues from pups were assayed for parameters of cellular growth. Fe-deficient pups (10 ppm Fe) had slightly lower body weights, lower hemoglobin, serum Fe, and liver Fe levels than those fed diets containing 100 or 250 ppm Fe. Thymus was most severely affected by Fe-deficiency. Organ weight, per cent body weight, and total DNA were decreased by at least 40% in Fe-deficient pups. Spleens from 10 ppm Fe pups had 30% less total DNA compared to controls due to decreased organ weight. There were no changes in spleen protein, lipid or DNA concentrations due to Fe deficiency. Measures of DNA and protein parameters in liver were similar among groups, although a 60% increase in liver lipid concentration was observed in pups from dams fed 10 ppm Fe. The results suggest that nutritional Fe deficiency during reproduction produces alterations in cellular growth of rapidly-divided lymphoid organs in offspring, while accumulation of DNA and protein in the liver is unaffected.

Iron status of suckling rats as influenced by maternal diet during gestation and lactation.

1. Two experiments are reported. In Expt 1, pregnant Sprague-Dawley rats (200-220 g) were given purified diets containing 35, 75, 150 or 300 mg Fe/kg throughout gestation and lactation. In Expt 2, the levels of Fe given were 250 and 300 mg/kg diet. 2. Litters were standardized at birth to contain seven pups. On day 20 of lactation blood, milk, spleen and liver were collected for Fe analysis. 3. A dietary Fe concentration of 35 mg/kg maintained maximum weight gain, food intake, liver and spleen weight, haemoglobin concentration and packed cell volume in the growing maternal rat through 20 d of lactation. Dam liver and spleen Fe concentrations were maximized between 75 and 250 mg Fe/kg diet. 4. Pups (20-d-old) nursed by dams given 35 mg Fe/kg tended to have lower body and organ weights compared to other groups. Liver and spleen Fe concentrations increased with increasing maternal dietary Fe and were significantly increased between 150 and 250 mg Fe/kg.

Lysozyme and other measures of immunity in young, mature, and aged rats.

Lysozyme, peroxidase, serum proteins, and immunoglobulins were measured in young (1 month), mature (13 months), and aged rats (25 months). Circulating levels of immunoglobulins G and A increased with maturity as did the globulin fraction of serum protein. Concentration of the bactericidal enzyme, lysozyme, was significantly increased in serum and kidney and significantly decreased in spleens of aged rats.

Folate depletion secondary to iron deficiency in the neonatal rat.

Two experiments were performed to investigate the effect of dietary iron deficiency during reproduction on folate status in rat dams and pups. In experiment 1, twenty pregnant Sprague-Dawley rats (190-200 g) were fed one of two diets (8 ppm Fe, 1 ppm folate or 250 ppm Fe, 1 ppm folate) throughout gestation and until day 18 of lactation when dams and their pups (seven per litter) were killed. Although there was no effect of iron deficiency on dam folate status, iron-deficient pups had decreased liver folate activity compared to controls. Milk free folate activity was significantly decreased by 34% in iron-deficient dams compared to controls. To determine if iron deficiency affected folate status at birth, experiment 2 was conducted. Nine pregnant rats (215-230 g) were fed one of two diets (6 ppm Fe, 1 ppm folate or 250 ppm Fe, 1 ppm folate) throughout gestation and until day 2 of lactation. Liver and kidney folate activities were similar in both groups of pups on day 2 of lactation. It is concluded that the stress of lactation superimposed on iron deficiency alters the folate composition of rat milk, and results in folate depletion in 18-day-old rat pups.