Nuts and plasma lipids: an almond-based diet lowers LDL-C while preserving HDL-C.

OBJECTIVE: To compare lipid-altering effects of an almond-based diet with an olive oil-based diet, against a cheese and butter-based control diet. METHODS: Forty-five free-living hyperlipidemic men (n = 12) and women (n = 33) with a mean plasma total cholesterol (TC) of 251 +/- 30 mg/dL followed one of three diets; almond-based, olive oil-based, or dairy-based for 4 weeks. Total fat in each diet was matched, and the study-provided sources of fat comprised the major portion of fat intake. RESULTS: Reductions in TC and low-density lipoprotein-cholesterol (LDL-C) between the three groups were significantly different from the almond group (both p < 0.001). Within group analysis revealed that the almond-based diet induced significant reductions in TC (p < 0.05), LDL-C (p < 0.001), and the TC:HDL ratio (p < 0.001), while HDL-C levels were preserved. TC and HDL-C in the control diet were significantly increased from baseline (both p < 0.05), while the olive oil-based diet resulted in no significant changes over the study period. Weight did not change significantly. CONCLUSION: Results suggest that the more favorable lipid-altering effects induced by the almond group may be due to interactive or additive effects of the numerous bioactive constituents found in almonds.

Characterization and genetic mapping of phosphoglucoisomerase mutations in mannitol-negative mutants of Pseudomonas aeruginosa.

Phosphoglucoisomerase (pgi) mutations in a number of independently isolated mannitol-negative mutants of Pseudomonas aeruginosa PAO1 were mapped on the chromosome by plasmid FP5-mediated conjugation and by cotransduction with the generalized transducing phages G101 and F116L. Mutant allele pgi-9001 exhibited linkage to ilvB, C-9059 (46-85%), car-9003 (93-100%), and pur-9047 (70%), but not with met-9011, in FP5-mediated conjugational crosses. All known pgi mutations and several previously uncharacterized mannitol-negative mutations exhibited transductional linkage to two independent car mutations at frequencies ranging from 13% to 42% and 53% to 99%, in transductional crosses mediated by phages G101 and F116L respectively. These pgi and mannitol-negative mutations also were cotransducible at very low frequencies (<1%) with two independent ilv mutations. Cotransduction of the car and ilv loci could not be detected. These data suggest the location of pgi within the first minute of the P. aeruginosa chromosome closely linked to the car marker and probably between the ilv and car loci. All of the mannitol-negative mutations that exhibited linkage to the car and ilv loci were characterized as pgi mutations by enzyme assays. A phenotypically similar, mannitol-negative mutant was shown to contain a mutation in glucose-6-phosphate dehydrogenase (zwf-9012) that maps to a different region on the chromosome.

The effect of acacia gum and a water-soluble dietary fiber mixture on blood lipids in humans.

Water-soluble dietary fibers (WSDF) are generally thought to lower cholesterol. This study compared the cholesterol-lowering effects of a medium viscosity WSDF mixture (psyllium, pectin, guar gum and locust bean gum) with an equal amount of WSDF from acacia gum, which has a lower viscosity. Hypercholesterolemic males (n = 13) and females (n = 16) were randomly assigned to one of two WSDF treatments provided in a low-calorie powder form for mixing into beverages (< 4 kcal/serving). Subjects were instructed to mix powders into their usual beverages and to consume them three times daily (5 g WSDF/serving) for 4 weeks while consuming their typical fat-modified diets. Exercise and body weights were also held constant. The WSDF mixture yielded a 10% decrease in plasma total cholesterol (from 251 +/- 20 to 225 +/- 19 mg/dL; p < 0.01), and a 14% reduction in low-density lipoprotein cholesterol (from 167 +/- 14 to 144 +/- 14 mg/dL; p < 0.001). No significant changes in plasma high-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol or triglycerides were observed. In contrast, the acacia gum-treated group showed no change in any plasma lipid parameters. The WSDF treatments did not produce significant changes in mean dietary intakes within or between treatment groups. These data support previous findings that a diet rich in select WSDF can be a useful cholesterol-lowering adjunct to a fat-modified diet, but that caution should be exercised in ascribing cholesterol-lowering efficacy to dietary fibers based solely on their WSDF classification. Finally, WSDF viscosity is a potential cholesterol-lowering factor to be explored further.

Effect of a diet high in monounsaturated fat from almonds on plasma cholesterol and lipoproteins.

The effect of almonds as part of a low saturated fat, low cholesterol, high-fiber diet was studied in 26 adults (13 men, 13 women). The baseline diet was modified in a similar way for all subjects by limiting meat, fatty fish, high-fat milk products, eggs, and saturated fat. Grains, beans, vegetables, fruit, and low-fat milk products were the foundation of the diet. During the almond diet period, raw almonds (100 mg/day) supplied 34 g/day of monounsaturated fatty acid (MUFA), 12 g/day of polyunsaturated fatty acid, and 6 g/day of saturated fatty acid. Almond oil was the only oil allowed for food preparation. There was a rapid and sustained reduction in low-density lipoprotein cholesterol without changes in high-density lipoprotein cholesterol. This was reflected in a total plasma cholesterol decrease from (means +/- SEM) 235 +/- 5.0 at baseline to 215 +/- 5.0 at 3 weeks, and to 214 +/- 5.0 mg/dl at 9 weeks (p less than 0.001). When the consumption of nuts high in MUFA increases the fat content of the diet, reduction rather than elevation of plasma cholesterol has to be expected, possibly due to the MUFA content of these nuts.

Role of water-soluble dietary fiber in the management of elevated plasma cholesterol in healthy subjects.

Guidelines for the use of water-soluble dietary fibers (WSDF) in the dietary management of elevated plasma cholesterol are not well-established. Consequently, 4 studies were conducted to explore the plasma lipid-lowering effects of a variety of WSDF. Studies were randomized, double-blind, placebo-controlled trials involving healthy men and women (plasma cholesterol greater than 5.17 mmol/liter; greater than 200 mg/dl). Study duration ranged from 4 to 12 weeks. The WSDF acacia gum yields a low viscosity, palatable beverage when mixed in water. However, despite its WSDF classification, acacia gum consumed for 4 weeks as the sole WSDF source (15 g of WSDF/day) or primary source in a WSDF mixture (17.2 g of WSDF/day; 56% derived from acacia gum) did not produce a significant lipid-lowering effect versus placebo. When 15 g of WSDF/day consisting of psyllium hust, pectin, and guar and locust bean gums (medium viscosity) was consumed for 4 weeks, significant reductions in cholesterol resulted (total cholesterol 8.3%, low-density lipoprotein cholesterol 12.4%; p less than 0.001) that were comparable to changes achieved with 10 g of WSDF/day from high-viscosity guar gum. The magnitude of the lipid-lowering effect was related to intake of WSDF ranging from 5 to 15 g/day (low-density lipoprotein cholesterol +0.8% [placebo], -5.6% [5 g/day], -6.8% [10 g/day], -14.9% [15 g/day]; p less than 0.01 for trend). The effects of WSDF on plasma lipids were similar for men and women. A diet rich in selected WSDF may be a useful adjunct to the dietary management of elevated plasma cholesterol.

Guar gum and plasma cholesterol. Effect of guar gum and an oat fiber source on plasma lipoproteins and cholesterol in hypercholesterolemic adults.

The hypolipidemic effect of guar gum (GG, 15 g/day) was compared with that of an oat fiber source (OFS, 77 g/day). Both treatments supplied the same amount of total dietary fiber (11 g/day) and were taken with water three times a day for 3 weeks at mealtime. Thirteen free-living adult men and women participated in the study. Their total plasma cholesterol (TC) was 244 +/- 21 mg/dl (mean +/- SD), and plasma triglycerides (TGLYs) were 149 +/- 93 mg/dl before the intervention. Diets were monitored to ensure that no changes occurred other than the replacement of carbohydrate calories for the 200 kcal/day supplied by the OFS. Combined averages for both of the crossover phases showed that GG induced a reduction in TC of 26 +/- 10 mg/dl and in low density lipoprotein cholesterol of 25 +/- 9 mg/dl. The OFS induced a reduction in TC of 9 +/- 13 mg/dl and in low density lipoprotein cholesterol of 11 +/- 4 mg/dl. Although both treatments were effective in reducing elevated TC, GG at the levels fed was significantly more effective (p less than 0.001) in reducing TC. Neither treatment induced significant changes in high density lipoprotein cholesterol or very low density lipoprotein cholesterol.

Mutation to Wider Virulence in Puccinia graminis f. sp. tritici: Evidence for the Existence of Loci Which Allow the Fungus To Overcome Several Host Stem Rust Resistance Genes Simultaneously.

Mutants of Puccinia graminis f. sp. tritici were obtained which were able to overcome simultaneously several host stem rust resistance (Sr) genes effective against the wild-type culture. These results suggest that, in addition to those Psr loci which relate specifically to host Sr genes in a "gene for gene" manner, one or more general loci may be present in this pathogen. The product(s) of these general genes may be necessary for the expression of various host Sr genes. The evolution of a super race capable of overcoming many Sr genes for resistance seems likely, as such a pathogen would not have to give up the many proteins predicted by the gene-for-gene relationship. Moreover, it appears that specificity in the wheat rust system is more complicated than suggested by the gene-for-gene concept.

Identification of eubacteria isolated from leaf cavities of four species of the N-fixing azolla fern as arthrobacter conn and dimmick.

The nutritional and physiological characteristics of 15 isolates from four species of the Azolla fern were determined. Although some minor variation existed in levels of urease activity, ability to utilize xylose, and formation of N(2) gas from NO(3), all 15 isolates were rather similar and believed to represent a single species. These eubacteria exhibited aminopeptidase activity and became viscous when treated with KOH, similar to gram-negative organisms; however, the absence of lipopolysaccharide and 2-keto-3-deoxyoctonate in cell walls indicated that they are truly gram-positive organisms. They are unusual because peptidoglycan could not be detected during most of their growth cycle. The presence of lysine as the major diamino acid in cell wall hydrolysates, the inability to hydrolyze cellulose, and the distinctive developmental pattern with rods and "V" forms present during log phase, becoming progressively shorter until cocci dominated during stationary and death phases, indicated that these organisms belong to the genus Arthrobacter Conn and Dimmick. With the exception of the inability to hydrolyze gelatin, their characteristics are consistent with those of the type species, Arthrobacter globiformis Conn and Dimmick.

Aflatoxigenic Potential for Aspergilli on sucrose substrates.

Sucrose concentrations of 3, 10, 20, and 30% in Czapek Dox broth served as the carbon source for growth, aflatoxin production, and sporulation for Aspergillus parasiticus NRRL 2999 and A. flavus NRRL 3557, 5862, and 5013. All cultures produced mycelial growth and sporulated in all sucrose concentrations during the 12-day growth period. The area of mycelial mat coverage per hour increased directly with increased sugar concentrations. The 20 and 30% sucrose concentrations inhibited mycelial growth for 5862. The 30% sucrose cultures of 3557 and 5862 failed to produce detectable levels of aflatoxins. All other isolates produced B1 and G1 in an approximately 4:1 ratio in all sucrose concentrations. Only 2999 was a substantial producer of aflatoxin in all 4 sucrose cultures, ranging from 72 to 96 micrograms/mL medium. A. flavus 5013 produced the most toxin, 144 and 126 micrograms/mL medium in the 10 and 20% sucrose cultures, respectively. The 10 and 20% sucrose cultures were most conducive to aflatoxin production. Since these sucrose levels correspond closely to the levels in many food and drink products, especially home-made products, care and attention should be taken to keep them free of aflatoxigenic spores. Extensive mycelial growth and sporulation, even in aflatoxigenic strains, do not necessarily result in comparably high aflatoxin levels. Routine extraction and quantitation procedures for aflatoxin were applicable and provided satisfactory results.

An indirect fluorescent antibody staining technique for determining population levels ofThiobacillus ferrooxidans in acid mine drainage waters.

Thiobacillus ferrooxidans is believed to be responsible for the oxidation of ferrous ion at low pH, the rate-limiting step in the oxidation of pyrite ores and subsequent formation of acid mine drainage (AMD). It has been suggested that efforts to control this environmental problem include procedures that would inhibit this bacterium. At present, a most probable number (MPN) procedure requiring a minimum of 10 days is used to enumerate this microorganism in natural waters. If control of AMD through inhibition ofT. ferrooxidans is to be feasible, it will be necessary to develop a more rapid method to determine population levels to facilitate application of control measures.An indirect fluorescent antibody (FA) staining technique was developed for this purpose which provided reliable estimates within a few hours. Artificial samples containing approximated numbers ofT. ferrooxidans were analyzed using the FA and MPN procedures, and the FA technique more closely approximated expected numbers of cells. The MPN method was excessively conservative, detecting only 3% to 21% of the cells enumerated by the FA procedure.

Defining dietary plant fibers in human nutrition.

Research on the nutritional aspects of dietary plant fibers in human nutrition has been plagued by many problems of definition, terminology, analytical procedures, as well as insufficient consideration of the interactions of other dietary components with the dietary fiber polymers. The use of the term non-nutritive has also led to some confusion, as many polymers of dietary fiber are digested by intestinal bacteria in humans. It appears extremely important for the orderly progress of this field that comprehensive terms be used cautiously and that perhaps a new umbrella term (such as plantix) should be introduced. The physiological effects of various polymers have been shown to differ considerably; thus the effect of dietary fiber should not be generalized. Analytical procedure should include both water-insoluble and water-soluble fractions and some consideration should be given to the non-polymeric, enzyme-indigestible compounds such as certain seed and leaf waxes.