Survival of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata after exposure to ethanol solutions at various temperatures.

AIMS: To quantify and model the toxicity of brief exposures of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata to heated, aqueous ethanol solutions. These fungi are common postharvest decay pathogens of fresh grapes and other produce. Sanitation of produce reduces postharvest losses caused by these and other pathogens. METHODS AND RESULTS: Spores of the fungi were exposed to solutions containing up to 30% (v/v) ethanol at 25-50 degrees C for 30 s, then their survival was determined by germination on semisolid media. Logistical, second-order surface-response models were prepared for each fungus. Subinhibitory ethanol concentrations at ambient temperatures became inhibitory when heated at temperatures much lower than those that cause thermal destruction of the spores by water alone. At 40 degrees C, the estimated ethanol concentrations that inhibited the germination of 50% (LD(50)) of the spores of B. cinerea, A. alternata, A. niger and R. stolonifer were 9.7, 13.5, 19.6 and 20.6%, respectively. CONCLUSIONS: Ethanol and heat combinations were synergistic. Control of spores of these fungi could be accomplished with much lower temperatures and ethanol concentrations when combined compared with either used alone. Botrytis cinerea and A. alternata were less resistant to the combination than A. niger or R. stolonifer.

Contrasting effects of t10,c12- and c9,t11-conjugated linoleic acid isomers on the fatty acid profiles of mouse liver lipids.

The purpose of this study was to examine the effects of two purified isomers of CLA (c9,t11-CLA and t10,c12-CLA) on the weights and FA compositions of hepatic TG, phospholipids, cholesterol esters, and FFA. Eight-week-old female mice (n = 6/group) were fed either a control diet or diets supplemented with 0.5% c9,t11-CLA or t10,c12-CLA isomers for 8 wk. Weights of liver total lipids and those of individual lipid fractions did not differ between the control and the c9,t11-CLA groups. Livers from animals fed the t10, c12-CLA diet contained four times more lipids than those of the control group; this was mainly due to an increase in the TG fractions (fivefold), but cholesterol (threefold), cholesterol esters (threefold), and FFA (twofold) were also significantly increased. Although c9,t11-CLA did not significantly alter the weights of liver lipids when compared with the control group, its intake was associated with significant reductions in the weight percentage (wt% of total FAME) of 18:1n-9 and 18:1n-7 in the TG fraction and with significant increases in the weight percentage of 18:2n-6 in the TG, cholesterol ester, and phospholipid fractions. On the other hand, t10,c12-CLA intake was linked with a significant increase in the weight percentage of 18:1n-9 and a decrease in that of 18:2n-6 in all lipid fractions. These changes may be the result of alterations in the activity of delta9-desaturase (stearoyl CoA desaturase) and the enzymes involved in the metabolism of 18:2n-6. Thus, the two isomers differed not only in their effects on the weights of total liver lipids and lipid fractions but also on the FA profile of the lipid fractions.

Trans-10,cis-12 CLA increases liver and decreases adipose tissue lipids in mice: possible roles of specific lipid metabolism genes.

Although consumption of CLA mixtures has been associated with several health effects, less is known about the actions of specific CLA isomers. There is evidence that the t10,c12-CLA isomer is associated with alterations in body and organ weights in animals fed CLA, but the mechanisms leading to these changes are unclear. The purpose of this study was to determine the effects of two commonly occurring isomers of CLA on body composition and the transcription of genes associated with lipid metabolism. Eight-week-old female mice (n = 11 or 12/group) were fed either a control diet or diets supplemented with 0.5% c9,t11-CLA or t10,c12-CLA isomers or 0.2% of the peroxisome proliferator-activated receptor alpha (PPARalpha) agonist fenofibrate for 8 wk. Body and retroperitoneal adipose tissue weights were significantly lower (6-10 and 50%, respectively), and liver weights were significantly greater (100%) in the t10,c12-CLA and the fenofibrate groups compared with those in the control group; body and tissue weights in the c9,t11-CLA group did not differ from those in the control group. Livers from animals in the t10,c12-CLA group contained five times more lipids than in the control group, whereas the lipid content of the fenofibrate group did not differ from that in the control group. Although fenofibrate increased the mRNA for PPARalpha, t10,c12-CLA decreased it. These results suggest that PPARalpha did not mediate the effects of t10,c12-CLA on body composition. The CLA isomers and fenofibrate altered mRNA levels for several proteins involved in lipid metabolism, but the most striking difference was the reduction of mRNA for leptin and adiponectin in the t10,c12-CLA group. These initial results suggest that changes associated with energy homeostasis and insulin action may mediate the effects of t10,c12-CLA on lipid metabolism.

Effect of feeding solanidine, solasodine and tomatidine to non-pregnant and pregnant mice.

The aglycone forms of three steroidal glycoalkaloids-solanidine (derived by hydrolytic removal of the carbohydrate side chain from the potato glycoalkaloids alpha-chaconine and alpha-solanine), solasodine (derived from solasonine in eggplants) and tomatidine (derived from alpha-tomatine in tomatoes)-were evaluated for their effects on liver weight increase (hepatomegaly) in non-pregnant and pregnant mice and on fecundity in pregnant mice fed for 14 days on a diet containing 2.4 mmol/kg of aglycone. In non-pregnant mice, observed ratios of % liver weights to body weights (%LW/BWs) were significantly greater than those of the control values as follows (all values in % vs matched controls+/-S.D.): solanidine, 25.5+/-13.2; solasodine 16.8+/-12.0; and tomatidine, 6.0+/-7.1. The corresponding increases in pregnant mice were: solanidine, 5.3+/-10.7; solasodine, 33.1+/-15.1; tomatidine, 8.4+/-9.1. For pregnant mice (a) body weight gains were less with the algycones than with controls: solanidine, -36.1+/-14.5; solasodine, -17.9+/-14.3; tomatidine, -11.9+/-18.1; (b) litter weights were less than controls: solanidine, -27.0+/-17.1; solasodine, -15.5+/-16.8; tomatidine, no difference; (c) the %LTW/BW ratio was less than that of the controls and was significant only for solasodine, -8.7+/-13.7; and (d) the average weight of the fetuses was less than the controls: solanidine, -11.2+/-15.2; solasodine, -11.4+/-9.4; tomatidine, no difference. Abortion of fetuses occurred in five of 24 pregnant mice on the solanidine and none on the other diets. To obtain evidence for possible mechanisms of the observed in vivo effects, the four glycoalkaloids (alpha-chaconine, alpha-solanine, solasonine and alpha-tomatine) mentioned above and the aglycones solanidine and tomatidine were also evaluated in in vitro assays for estrogenic activity. Only solanidine at 10 microM concentration exhibited an increase in the MCF-7 human breast cancer cell proliferation assay. Generally, the biological effects of solanidine differ from those of the parent potato glycoalkaloids. Possible mechanisms of these effects and the implication of the results for food safety and plant physiology are discussed.

Similar effects of c9,t11-CLA and t10,c12-CLA on immune cell functions in mice.

Published results regarding the effects of CLA on immune cell functions have ranged from stimulation to inhibition. In those studies, a mixture of CLA isomers were used, and food intake was not controlled. We have examined whether the discrepancies in the results of earlier studies may be due to the lack of controlled feeding and whether the two isomers of CLA may differ in their effects on immune cell functions. Three groups of C57BL/6 female mice were fed either a control, c9,t11-CLA-, or t10,c12-CLA (0.5 wt%)-supplemented diet, 5 g/d, for 56 d. At the end of the study, the number of immune cells in spleens, bone marrows, or in circulation; proliferation of splenocytes in response to T and B cell mitogens; and prostaglandin secretion in vitro did not differ among the three groups. Both CLA isomers significantly increased in vitro tumor necrosis factor alpha and interleukin (IL)-6 secretion and decreased IL-4 secretion by splenocytes compared to those in the control group. Thus, the two CLA isomers had similar effects on all response variables tested. The discrepancies among the results from previous studies did not seem to be caused by the differences in the isomer composition of CLA used.

Dietary supplementation with conjugated linoleic acid increased its concentration in human peripheral blood mononuclear cells, but did not alter their function.

The purpose of this study was to examine if conjugated linoleic acid (CLA) supplementation of diets would alter fatty acid (FA) composition and function of peripheral blood mononuclear cells (PBMC). Seventeen women, 20-41 yr, participated in a 93-d study conducted at the Metabolic Research Unit. The same diet (19, 30, and 51% energy from protein, fat, and carbohydrate, respectively) was fed to all subjects throughout the study. Seven subjects (control group) supplemented their diet with six daily capsules (1 g each) of placebo oil (sunflower) for 93 d. For the other 10 subjects (CLA group), the supplement was changed to an equivalent amount of Tonalin capsules for the last 63 d of the study. Tonalin provided 3.9 g/d of a mixture of CLA isomers (trans-10,cis-12, 22.6%; cis-11,trans-13, 23.6%; cis-9,trans-11, 17.6%; trans-8,cis-10, 16.6%; other isomers 19.6%), and 2.1 g/d of other FA. PBMC isolated on study days 30 and 90 were used to assess intracellular cytokines by flow cytometry, secreted cytokines, and eicosanoid by enzyme-linked immonosorbent assay, and FA composition by gas-liquid chromatography. After supplementation, total CLA concentration increased from 0.012 to 0.97% (P < 0.0001) in PBMC lipids, but it did not significantly alter the concentration of other FA. CLA supplementation did not alter the in vitro secretion of prostaglandin E2, leukotriene B4, interleukin-1beta (IL-1beta), or tumor necrosis factor alpha (TNFalpha) by PBMC simulated with lipopolysaccharide, and the secretion of IL-2 by PBMC stimulated with phytohemagglutinin. Nor did it alter the percentage T cells producing IL-2, interferon gamma, and percentage of monocytes producing TNFalpha. The intracellular concentration of these cytokines was also not altered. None of the variables tested changed in the control group. Our results show that CLA supplementation increased its concentration in PBMC lipids, but did not alter their functions.

Dietary conjugated linoleic acid did not alter immune status in young healthy women.

The purpose of this study was to examine whether conjugated linoleic acid (CLA) supplementation in human diets would enhance indices of immune status as reported by others for animal models. Seventeen women, 20-41 yr, participated in a 93-d study conducted in two cohorts of 9 and 8 women at the Metabolic Research Unit of Western Human Nutrition Research Center. Seven subjects were fed the basal diet (19, 30, and 51% energy from protein, fat, and carbohydrate, respectively) throughout the study. The remaining 10 subjects were fed the basal diet for the first 30 d, followed by 3.9 g CLA (Tonalin)/d for the next 63 d. CLA made up 65% of the fatty acids in the Tonalin capsules, with the following isomeric composition: t10, c12, 22.6%; c11, t13, 23.6%; c9, t11, 17.6%; t8, c10, 16.6%; and other isomers 19.6%. Most indices of immune response were tested at weekly intervals, three times at the end of each period (stabilization/intervention); delayed-type hypersensitivity (DTH) to a panel of six recall antigens was tested on study day 30 and 90; all subjects were immunized on study day 65 with an influenza vaccine, and antibody titers were examined in the sera collected on day 65 and 92. None of the indices of immune status tested (number of circulating white blood cells, granulocytes, monocytes, lymphocytes, and their subsets, lymphocytes proliferation in response to phytohemagglutinin, and influenza vaccine, serum influenza antibody titers, and DTH response) were altered during the study in either dietary group. Thus, in contrast to the reports with animal models, CLA feeding to young healthy women did not alter any of the indices of immune status tested. These data suggest that short-term CLA supplementation in healthy volunteers is safe, but it does not have any added benefit to their immune status.

High-temperature forced-air treatment alters the quantity of flavor-related, volatile constituents present in navel and Valencia oranges.

A number of volatile compounds that contribute to orange flavor were quantified following high-temperature forced-air (HTFA) treatment of the fruit to determine if a relationship exists between the flavor loss that is observed following HTFA treatment and the volatile composition of the juice. Following different durations of HTFA treatment, fruit were stored for a period of 4 weeks and juiced and the juice subjected to headspace analysis using either a Tenax/Carbotrap column or a solid-phase microextraction device for trapping of the volatiles. alpha-Pinene, beta-myrcene, and limonene were reduced in amount by 60%, 58%, and 34%, respectively, over the course of the 5-h HTFA treatment. The influence of heat on the amount of decanal was less clear, although in one of the two fruit lots there was little change. The amount of ethanol was reduced by 70% after the initial hour of HTFA treatment and then steadily increased to exceed the initial amount during the remaining 4 h of the treatment. Taste evaluations of the fruit showed a reduction of flavor quality following 4 h or more of treatment. Percent acidity and soluble solids, two other very important determinants of flavor, were nearly unchanged by treatment. Alterations in the volatile constituents of oranges by HTFA treatment may be an important reason behind the negative impact of this treatment on flavor quality.

Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy men.

The purpose of this study was to examine the effects of feeding docosahexaenoic acid (DHA) as triacylglycerol on the fatty acid composition, eicosanoid production, and select activities of human peripheral blood mononuclear cells (PBMNC). A 120-d study with 11 healthy men was conducted at the Metabolic Research Unit of Western Human Nutrition Reach Center. Four subjects (control group) were fed the stabilization diet throughout the study; the remaining seven subjects were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg D alpha-tocopherol acetate per day. PBMNC fatty acid composition and eicosanoid production were examined on day 30 and 113; immune cell functions were tested on day 22, 30, 78, 85, 106, and 113. DHA feeding increased its concentration from 2.3 to 7.4 wt% in the PBMNC total lipids, and decreased arachidonic acid concentration from 19.8 to 10.7 wt%. It also lowered prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production, in response to lipopolysaccharide, by 60-75%. Natural killer cell activity and in vitro secretion of interleukin-1beta and tumor necrosis factor alpha were significantly reduced by DHA feeding. These parameters remained unchanged in the subjects fed the control diet. B-cell functions as reported here and T-cell functions that we reported previously were not altered by DHA feeding. Our results show that inhibitory effects of DHA on immune cell functions varied with the cell type, and that the inhibitory effects are not mediated through increased production of PGE2 and LTB4.

Dietary docosahexaenoic acid and immunocompetence in young healthy men.

The purpose of this study was to examine the effect of dietary docosahexaenoic acid (DHA), in the absence of eicosapentaenoic acid, on human immune response (IR). A 120-d study with 11 healthy men was conducted at the Metabolic Research Unit of the Western Human Nutrition Research Center. Four subjects (control group) were fed the stabilization or basal diet (15, 30, and 55% energy from protein, fat, and carbohydrate, respectively) throughout the study; the remaining seven subjects (DHA group) were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg d-alpha-tocopherol acetate per day. Indices of IR were examined on study day 22, 30, 78, 85, 106, and 113. Addition of DHA at moderately high levels did not alter the proliferation of peripheral blood mononuclear cells cultured with phytohemagglutinin or concanavalin A, or the delayed hypersensitivity skin response. Also, additional DHA did not alter the number of T cells producing interleukin 2 (IL2), the ratio between the helper/suppressor T cells in circulation, or the serum concentrations of immunoglobulin G, C3, and interleukin 2 receptor (IL2R). DHA supplementation, however, caused a significant (P = 0.0001) decrease in the number of circulating white blood cells which was mainly due to a decrease in the number of circulating granulocytes. The number of lymphocytes in peripheral circulation was not affected by Dietary DHA enrichment, but the percentage of lymphocytes in white blood cells increased because of a reduction in granulocyte numbers. None of these indices was changed in the control group. Our results show that when total fat intake is low and held constant, DHA consumption does not inhibit many of the lymphocyte functions which have been reported to be inhibited by fish oil consumption.

Arachidonic acid supplementation enhances synthesis of eicosanoids without suppressing immune functions in young healthy men.

This study was conducted to determine the effects of arachidonic acid (AA) supplementation on human immune response (IR) and on the secretion of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4). Ten healthy men (20-38 yr) participated in the study and lived at the Metabolic Suite of the Western Human Nutrition Research Center. They were fed a basal diet (57, 27, and 16 energy percentage from carbohydrate, fat, and protein, respectively, and AA 200 mg/d) for the first 15 d of the study. Additional AA (1.5 g/d) was added to the diet of six men from day 16 to 65, while the remaining four subjects remained on the basal diet. The diets of the two groups were crossed-over from day 66 to 115. In vitro indices of IR were examined using blood drawn on days 15, 58, 65, 108, and 115. Influenza antibody titers were determined in the sera prepared from blood drawn on days 92 and 115 (23 d postimmunization). AA supplementation caused significant increases in the in vitro secretion of LTB4, and PGE2, but it did not alter the in vitro secretion of tumor necrosis factor alpha; interleukins 1 beta, 2, 6; and the receptor for interleukin 2. Nor did it change the number of circulating lymphocytes bearing markers for specific subsets (B, T, helper, suppressor, natural killer) and the serum antibody titers against influenza vaccine. The opposing effects of PGE2 and LTB4 may have led to the lack of change in immune functions tested.

Effects of dietary arachidonic acid on human immune response.

Arachidonic acid (AA) is a precursor of eicosanoids, which influence human health and the in vitro activity of immune cells. We therefore examined the effects of dietary AA on the immune response (IR) of 10 healthy men living at our metabolic suite for 130 d. All subjects were fed a basal diet containing 27 energy percentage (en%) fat, 57 en% carbohydrate, and 16 en% protein (AA, 200 mg/d) for the first and last 15 d of the study. Additional AA (1.5 g/d) was incorporated into the diet of six men from day 16 to 65 while the remaining four subjects continued to eat the basal diet. The diets of the two groups were crossed-over from day 66 to 115. In vitro indexes of IR were examined using the blood samples drawn on days 15, 58, 65, 108, 115, and 127. The subjects were immunized with the measles/mumps/rubella vaccine on day 35 and with the influenza vaccine on day 92. Dietary AA did not influence many indexes of IR (peripheral blood mononuclear cell proliferation in response to phytohemagglutinin, Concanavalin A, pokeweed, measles/mumps/rubella, and influenza vaccines prior to immunization, and natural killer cell activity). The post-immunization proliferation in response to influenza vaccine was about fourfold higher in the group receiving high-AA diet compared to the group receiving low-AA diet (P = 0.02). Analysis of variance of the data pooled from both groups showed that the number of circulating granulocytes was significantly (P = 0.03) more when the subjects were fed the high-AA diet than when they were fed the low-AA diet. The small increases in granulocyte count and the in vitro proliferation in response to influenza vaccine caused by dietary AA may not be of clinical significance. However, the lack of any adverse effects on IR indicates that supplementation with AA may be done safely when needed for other health reasons.

Improved Control of Green Mold of Citrus with Imazalil in Warm Water Compared with Its Use in Wax.

The effectiveness of imazalil for the control of citrus green mold (caused by Penicillium digitatum) improved significantly when fruit were treated with heated aqueous solutions of the fungicide as compared with the current commercial practice of spraying wax containing imazalil on fruit. When applied at less than 500 µg·ml-1 in solutions heated to 37.8°C, control of postharvest green mold of citrus was significantly superior to applications of 4,200 µg·ml-1 imazalil in wax sprayed on fruit at ambient temperatures. The improvement in imazalil efficacy was obtained with a decrease in fungicide residues on the fruit. Residues of about 3.5 µg·g-1 imazalil deposited by the application of imazalil in wax reduced the incidence of green mold on lemons from 94.4% among untreated controls to 15.1%, whereas an equal residue deposited by passing fruit through heated aqueous imazalil reduced green mold incidence to 1.3%. Similar differences were found in tests with oranges. Residues of 2 and 3.5 µg·g-1 imazalil were needed to control the sporulation of P. digitatum on oranges and lemons, respectively. The mode of application of imazalil did not influence control of sporulation. The influence of immersion time, imazalil concentration, and solution temperature on imazalil residues on oranges and lemons was determined in tests using commercial packing equipment, and a model that describes residue deposition was developed. Residues after a 30- or 60-s treatment in heated aqueous imazalil were sufficient to control sporulation, but residues after 15-s treatments were too low and required an additional application of 1,070 µg·ml-1 imazalil in wax to deposit an amount of imazalil sufficient to control sporulation. An imazalil-resistant isolate of P. digitatum was significantly controlled by heated aqueous imazalil. The incidence of green mold of navel oranges was reduced from 98.8 to 17.4% by treatment in 410 µg·ml-1 imazalil at 40.6°C for 90 s. However, control of the resistant isolate required imazalil residues on the fruit of 7.9 µg·g-1, which is within the U.S. tolerance of 10 µg·g-1 but above the 5 µg·g-1 tolerance of some countries that import citrus fruit from the United States.

Influence of Concentration of Soda Ash, Temperature, and Immersion Period on the Control of Postharvest Green Mold of Oranges.

Oranges were inoculated with spores of Penicillium digitatum, the citrus green mold pathogen, and immersed 24 h later in heated soda ash (Na2CO3, sodium carbonate) solutions to control postharvest citrus green mold. Oranges were immersed for 1 or 2 min in solutions containing 0, 2, 4, or 6% (wt/vol) soda ash heated to 35.0, 40.6, 43.3, or 46.1°C. After 3 weeks of storage at 10°C, the number of decayed oranges was determined. Soda ash significantly controlled green mold in every test. The most effective control of green mold was obtained at 40.6 or 43.3°C with 4 or 6% soda ash. The concentration of soda ash greatly influenced efficacy, whereas the influences of temperature or immersion period on soda ash efficacy were small. Solutions of 4 and 6% soda ash were similar in efficacy and provided superior control of green mold compared with 2% soda ash. The control of green mold by soda ash solutions heated to 40.6 or 43.3°C was slightly superior to control by solutions heated to 35.0 or 46.1°C. The control of green mold by 1-min immersion of inoculated oranges in heated soda ash solutions was inferior to immersion for 2 min, but the magnitude of the difference, particularly with 6% soda ash, was small. A second-order response surface model without interactions was developed that closely described the influence of soda ash concentration, temperature, and immersion period on efficacy. The efficacy of soda ash under commercial conditions was better than that predicted by the model, probably because under commercial conditions the fruit were rinsed less thoroughly with water after treatment than in laboratory tests. The primary finding of this work was that soda ash controlled 24-h-old green mold infections at commercially useful levels using shorter immersion periods and lower temperatures than those recommended by other workers for the use of soda ash on lemons. The oranges were not visibly injured in any test.

Feeding of potato, tomato and eggplant alkaloids affects food consumption and body and liver weights in mice.

Reduced liver weight was used to evaluate the potential toxicity in mice of four naturally occurring steroidal glycoalkaloids: alpha-chaconine and alpha-solanine, alpha-tomatine and solasonine. Increased liver weights was used to evaluate the three corresponding steroidal aglycones: solanidine, tomatidine, and solasodine and the non-alkaloid adrenal steroid dehydroepiandrosterone (DHEA). Adult female Swiss-Webster mice were fed diets containing test compound concentrations of 0 (control), 1.2, 2.4 or 4.8 mmol/kg diet for 7, 14 or 28 d. Absolute liver weights (LW) and relative liver weights (liver weight/body weight x 100, %LW/BW) were determined at autopsy. The %LW/BW was lower than that of controls in mice fed the potato glycoalkaloid alpha-chaconine (-10%, P < or = 0.05) for 7 d with the 2.4 mmol/kg diet dose. Under these same conditions, %LW/BW was greater than that of controls in mice fed two aglycones: solanidine (27%, P < or = 0.001) and solasodine (8%, P < or = 0.01). Relative liver weight increases induced by the aglycones were determined under time and dose conditions in which differences in body weight and food consumption were not significant (2.4 mmol/kg diet for 28 d). Under these conditions, the observed %LW/BW increases relative to the controls were as follows: solanidine (32%, P < or = 0.001), solasodine (22%, P < or = 0.001) and DHEA (16%, P < or = 0.001). Solanidine, solasodine and DHEA were equally potent and were more potent than tomatidine. We also observed that the greater %LW/BW in mice fed 2.4 mmol/kg diet solasodine or solanidine for 14 d declined to near control values if they were fed control diets for another 14 d. The increase in relative liver weight induced by solanidine and solasodine is a reversible adaptive response. These findings and the apparent effects of structure on biological activity should serve as a guide for the removal of the most toxic ++compounds from plant foods. The implications of the results for food safety and health are discussed.

Effects of low-copper diets on human immune response.

We examined the effects of low-copper diets on indexes of immune response of 11 healthy men (aged 21-32 y) during a 90-d metabolic suite study. Daily copper intake for the first 24 d, next 42 d, and the last 24 d of the study was 0.66, 0.38, and 2.49 mg, respectively. Feeding the diet with 0.38 mg Cu/d was associated with a significant (P < or = 0.05) decrease in the proliferation of peripheral blood mononuclear cells cultured with phytohemagglutinin, Concanavalin A, or pokeweed, and an increase in the percentage of circulating B cells (CD 19+), but had no effect on the concentration of serum interleukin 2 receptor, the percentage of peripheral monocytes, neutrophils, CD3+, CD4+, or CD8+ T cells; or on the neutrophil phagocytic activity. Feeding 2.49 mg Cu/d for 24 d prevented further decreases in the indexes affected by the low-copper diet but did not restore them to the prestudy concentrations, even though plasma copper and ceruloplasmin concentrations were restored to normal.

Dietary alpha-linolenic acid alters tissue fatty acid composition, but not blood lipids, lipoproteins or coagulation status in humans.

We examined the effect of dietary alpha-linolenic acid (ALA) on the indices of lipid and coagulation status and on the fatty acid composition of serum and peripheral blood mononuclear cell (PBMNC) lipids in ten healthy men (age 21-37 yr) who consumed all their meals at the Western Human Nutrition Research Center for 126 d. There was a stabilization period of 14 d at the start when all 10 subjects consumed the basal diet (BD) containing 23.4 energy percent (en%) fat and two intervention periods of 56 d each. During the first intervention period, 5 subjects consumed the BD containing 23.4 en% fat, and 5 subjects consumed a diet providing 6.3% calories from alpha-linolenic acid [flaxseed oil (FSO) diet containing 28.8 en% fat]. Diets were crossed over between the two groups during the second intervention period. Feeding the FSO diet did not significantly alter serum triglycerides, cholesterol, high-density lipoproteins, low-density lipoproteins, apoprotein A-I and apoprotein B when compared to the corresponding values in the subjects fed the BD, nor was there any effect of the FSO diet on the bleeding time, prothrombin time and partial prothrombin time for these subjects. Feeding the ALA-containing diet did cause a significant increase in ALA concentration in serum (P < 0.001) and PBMNC lipids (P < 0.05). It also caused a significant increase (P < 0.05) in the eicosapentaenoic and docosapentaenoic acid contents of PBMNC lipids, and a decrease (P < 0.01) in linoleic and eicosatrienoic acid contents of serum lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Simple In Vivo Production and Storage Methods for Steinernema carpocapsae Infective Juveniles.

Methods are described for standardized in vivo production, rapid harvest, and storage, in a concentrated form, of infective juveniles of the entomopathogenic nematode, Steinernema carpocapsae Mexican strain Kapow selection. Nematodes were stored in nematode wool configurations, consisting of mats of intertwined infective juveniles. Freshly harvested nematodes are readily available in adequate quantities for laboratory and small-scale field evaluations as well as cottage industry production.

The micronucleus test: statistical design and analysis.

Alternative statistical procedures are discussed which may be employed to compare the incidences among treatment groups of micronucleated polychromatic and normochromatic erythrocytes and their ratios. Comparison of incidences of micronucleated polychromatic erythrocytes using a sequential sampling strategy based on the negative binomial distribution is shown to require fewer animals for the same sensitivity of test than a similar procedure based on the binomial distribution. The sequential test is superior, both in power and number of animals required, to an alternative 1-stage test based on the same distribution. The procedure described permits the investigator to optimize the number of animals in each test group and the number of cells counted per animal to detect a predetermined increase in the incidence of micronucleated cells over that observed in the control population within chosen limits of type I and type II error. An alternative sequential approach based on the binomial distribution is presented, which is applicable when the number of cells analyzed per animal is variable.