Micronutrients in women's health and immune function.

Lawrence J. Machlin's contributions to elucidating the roles of nutrients in optimizing human health included the support of research in the areas of women's health and immune function. Several essential nutrients have been shown to affect women's health throughout the different life stages. Symptoms of premenstrual syndrome affect the vast majority of menstruating women, and calcium supplementation significantly reduces physical and emotional symptoms. Premenstrual syndrome in fact might be a predictor of osteoporosis induced by low calcium intake. Periconceptional multivitamin supplementation has reduced the risk of serious birth defects, premature delivery, and low birth weight by 50% and improved maternal health during pregnancy. Micronutrients of particular importance for prevention of adverse pregnancy outcomes are folic acid, zinc, and iron. However, if the preterm delivery is caused by preeclampsia, then data suggest that calcium supplementation and high doses of vitamins C and E significantly reduce that risk. Well-controlled studies consistently have shown that calcium supplementation, with or without vitamin D, significantly reduces the risk of hip fracture. Antioxidants such as vitamins C and E have been shown to reduce the risk of fracture in women smokers. As in the rapidly growing embryo, the immune system includes rapidly multiplying cells whose functions are dramatically affected by an individual's micronutrient status. Multivitamins have been shown to enhance many aspects of immune response, and antioxidant micronutrients consistently have been found to enhance lymphocyte-proliferative responses and skin-test responses, especially in the elderly.

Absorbability and cost effectiveness in calcium supplementation.

BACKGROUND: Cost-effectiveness of calcium supplementation depends not only on the cost of the product but on the efficiency of its absorption. Published cost-benefit analyses assume equal bioavailability for all calcium sources. Some published studies have suggested that there are differences in both the bioavailability and cost of the major calcium supplements. DESIGN: Randomized four period, three-way cross-over comparing single doses of off-the-shelf commercial calcium supplements containing either calcium carbonate or calcium citrate compared with a no-load blank and with encapsulated calcium carbonate devoid of other ingredients; subjects rendered fully vitamin D-replete with 10 microg/day 25(OH)D by mouth, starting one week prior to the first test. SUBJECTS: 24 postmenopausal women METHODS: Pharmacokinetic analysis of the increment in serum total and ionized calcium and the decrement in serum iPTH induced by an oral calcium load, based upon multiple blood samples over a 24-hour period; measurement of the rise in urine calcium excretion. Data analyzed by repeated measures ANOVA. Cost calculations based on average retail prices of marketed products used in this study from April through October, 2000. RESULTS: All three calcium sources (marketed calcium carbonate, encapsulated calcium carbonate and marketed calcium citrate) produced identical 24-hour time courses for the increment in total serum calcium. Thus, these were equally absorbed and had equivalent bioavailability. Urine calcium rose slightly more with the citrate than with the carbonate preparations. but the difference was not significant. Serum iPTH showed the expected depression accompanying the rise in serum calcium, and there were no significant differences between products. CONCLUSION: Given the equivalent bioavailability of the two marketed products, the cost benefit analysis favors the less expensive carbonate product.

Mitochondrial DNA from the liverwort Marchantia polymorpha: circularly permuted linear molecules, head-to-tail concatemers, and a 5' protein.

Mapping predicts that the mitochondrial genome of the liverwort Marchantia polymorpha exists as a circular molecule, although nearly all the mitochondrial DNA (mtDNA) is found as genome-sized and multigenomic molecules in linear and branched form. We used restriction enzymes with one recognition site per genome, end-specific exonucleases and pulsed-field gel electrophoresis (PFGE) to analyze the arrangement of genomic units and the terminal structure of the molecules. We find a head-to-tail arrangement in the concatemers and circular permutation in both the monomeric and multigenomic molecules. The termini contain covalently bound protein at the 5' end and an open (unblocked) 3' end. We find that the standard in-gel procedure used to prepare large DNA molecules for PFGE may introduce extraction artifacts leading to erroneous conclusions about the termini. These artifacts can be reduced by omitting high salt (high EDTA) and protease during mitochondrial lysis. Our results suggest that the mtDNA may use a T4 phage-like mechanism of replication and that the linear molecules may be due to strand breaks mediated by type II topoisomerase.

The form of chromosomal DNA molecules in bacterial cells.

The circular concept of the bacterial chromosome was based initially on experiments involving conjugation mapping and autoradiographic imaging of DNA. This view was then supported by DNA fragment mapping, genome sequencing, and the analysis of linear DNA produced by a single cleavage of chromosomal DNA. A circular chromosome is also indicated by the existence of a mechanism for segregating dimeric chromosomes produced by recombination and the replication of DNA on both sides of the replication terminus. The evidence for circularity is reviewed here and found to be compatible with either a circular or a linear chromosomal DNA molecule. Moving pictures of ethidium-stained DNA revealed most chromosomal DNA as a rosette form with loops emanating from a dense node or as a network of strands lacking a node. This description applies to Escherichia coli, Agrobacterium tumefaciens, Pyrococcus endeavorii, Vibrio cholerae, and both the linear-mapping chromosome of Streptomyces lividans and its circular-mapping derivative. Networks without nodes were found for two linear-mapping Borrelia species. For the E. coli chromosome, open-form circles of various sizes were found only at extremely low frequency. The node of the rosette was reduced in size or eliminated in recA mutants, as well as by treatment with either ribonuclease, topoisomerase IV, 1 M NaCl, or lysozyme. A model is presented for the bacterial chromosome in which the DNA is compacted by many points of strand association (including recombination junctions, tangles and knots) created during the repair of DNA damage that occurs many times in each chromosome replication cycle.

Calcium supplementation and iron status of females.

Iron balance is regulated in part by the level of iron absorption, which is influenced by iron stores and the level of erythropoietic activity. In short-term absorption studies, dietary calcium and supplemental doses of calcium chloride or calcium carbonate inhibited iron absorption from concomitantly consumed meals. In contrast, several long-term intervention studies of the effect of calcium supplementation on iron status in populations at potentially high risk for compromised iron status failed to show reductions in various indicators of iron status including serum ferritin levels. The evidence suggests that long-term consumption of calcium supplements does not affect overall iron status. An adaptive response, possibly involving an upregulation in the efficiency of iron absorption, has been suggested as a possible explanation for the disparity between the results from short- and long-term studies.

A prospective study of age and lifestyle factors in relation to community-acquired pneumonia in US men and women.

BACKGROUND: Information is limited on risk factors for community-acquired pneumonia (CAP) in free-living populations. We examined the associations of age, smoking status, body mass index (BMI), weight change during adulthood, physical activity, and alcohol intake with risk of CAP among men and women. METHODS: The study population included 26,429 men aged 44 to 79 years from the Health Professionals Follow-up Study and 78,062 women aged 27 to 44 years from the Nurses' Health Study II. Information was collected by biennial mailed questionnaires and the main outcome was physician-diagnosed incident pneumonia. RESULTS: There were 290 cases among men (6 years of follow-up) and 305 cases among women (2 years of follow-up). Age, smoking status, BMI, physical activity, and alcohol intake were taken into account in the multivariate logistic regression model. There was a dose-response relation between aging and risk of CAP among men. Compared with never smokers, current smoking was associated with risk of CAP among men (relative risk, 1.46; 95% confidence interval, 1.00-2.14) and women (relative risk, 1.55; 95% confidence interval, 1.15-2.10). In addition, BMI was directly associated with an increased risk of CAP among women. Compared with the participants who maintained their weight during adulthood, the risks were nearly 2-fold higher among men and women who gained 40 lb or more (> or =18 kg). The risk of CAP decreased with increasing physical activity among women. We also found no significant relation between alcohol intake and risk of CAP among men and women. CONCLUSIONS: Smoking and excessive weight gain are risk factors for CAP among men and women, and physical activity was inversely associated with risk of CAP only among women. The incidence of CAP could possibly be decreased by lifestyle factors.

Use of vitamin-mineral supplements by female physicians in the United States.

BACKGROUND: Rates of vitamin-mineral supplement use by US female physicians are unknown but are of particular interest for several epidemiologic and clinical reasons. OBJECTIVE: The objective was to determine rates of and variations in vitamin-mineral supplement use among US female physicians. DESIGN: We used data from the Women Physicians' Health Study, a large (n = 4501) national, randomly sampled mail survey of female physicians aged 30-70 y. RESULTS: Half of the physicians took a multivitamin-mineral supplement; 35.5% of these did so regularly. However,

Prokaryotic and eukaryotic chromosomes: what's the difference?

It is widely held that the profound differences in cellular architecture between prokaryotes and eukaryotes, in particular the housing of eukaryotic chromosomes within a nuclear membrane, also extends to the properties of their chromosomes. When chromosomal multiplicity, ploidy, linearity, transcriptional silencing, partitioning, and packaging are considered, no consistent association is found between any of these properties and the presence or absence of a nuclear membrane. Some of the perceived differences can be attributed to cytological limitations imposed by the small size of bacterial nucleoids and the arbitrary choice of representative organisms for comparison. We suggest that the criterion of nucleosome-based packaging of chromosomal DNA may be more useful than the prokaryote/eukaryote dichotomy for inferring the broadest phylogenetic relationships among organisms.

The potential for dietary supplements to reduce premenstrual syndrome (PMS) symptoms.

Many types of dietary supplements have been advocated for the reduction of certain symptoms of premenstrual syndrome (PMS). However, only one supplement-calcium-has been demonstrated to be of significant benefit in a large, rigorous, double-blind, placebo-controlled trial. Limited evidence suggests that magnesium, vitamin E and carbohydrate supplements might also be useful, but additional research is needed to confirm these findings. Trials of vitamin B6 supplementation have had conflicting results, and high doses of this vitamin taken for prolonged periods of time can cause neurological symptoms. Trials of evening primrose oil have also had conflicting results; the two most rigorous studies showed no evidence of benefit. A variety of herbal products are suggested to reduce symptoms of PMS. The efficacy of these products is uncertain because of a lack of consistent data from scientific studies. Health professionals should be aware of the possible use of these supplements and ask those with PMS about their use of such products and counsel them based upon the totality of evidence.

Supplemental calcium for the prevention of hip fracture: potential health-economic benefits.

We assessed the cost-effectiveness of daily calcium supplementation for the prevention of primary osteoporotic hip fractures. The assessment was based on our meta-analysis of the published relative-risk estimates from 3 double-masked, placebo-controlled, clinical trials and our analysis of raw data from the National Health and Nutrition Examination Survey 1988-1994 on the daily intake of calcium supplements by adults in the United States. These data were then used to estimate the preventable proportion of hip fractures. The 1995 National Hospital Discharge Survey database provided the number and demographic characteristics of patients discharged with a primary diagnosis of hip fracture, as well as their discharge destination. The 1990 itemized costs of hip fractures, as estimated by the US Congress Office of Technology Assessment, were inflated to 1995 dollars using the medical care component of the Consumer Price Index. Using these inflated itemized costs, we then estimated the weighted average expenditures, reflecting both the types of services associated with specific hospital-discharge destinations and the demographic characteristics of discharged patients. The cost of supplements containing 1200 mg/d of elemental calcium for the mean duration (34 months) of the 3 clinical trials was calculated on the basis of 1998 unit-price and market-share data for 6 representative products. For 1995, the data indicate that 290,327 patients aged > or =50 years were discharged from US hospitals with a primary diagnosis of hip fracture, at our estimated direct cost of $5.6 billion. Based on the risk reductions seen in the 3 trials, we estimated that 134,764 hip fractures and $2.6 billion in direct medical costs could have been avoided if individuals aged > or =50 years consumed approximately 1200 mg/d of supplemental calcium. Additional savings could be expected, because this intervention is also associated with significant reductions in the risk for all nonvertebral fractures. Comparing the cost of calcium with the expected medical savings from hip fractures avoided, it is cost-effective to give 34 months of calcium supplementation to women aged > or =75 years in the United States. If, as the published studies suggest, shorter periods of supplementation result in an equivalent reduction in the risk of hip fractures, calcium supplementation becomes cost-effective for all adults aged > or =65 years in the United States. The data support encouraging older adults to increase their intake of dietary calcium and to consider taking a daily calcium supplement. Even small increases in the usage rate of supplementation are predicted to yield significant savings and to reduce the morbidity and mortality associated with hip fracture at an advanced age.

Effect of UV exposure and beta-carotene supplementation on delayed-type hypersensitivity response in healthy older men.

OBJECTIVES: The aims of this study were to determine if ultraviolet light (UV) is immunosuppressive in healthy older males, if beta-carotene (betaC) supplementation could prevent any observed UV-induced immunosuppression, and to compare these effects with those observed previously in younger men. METHODS: The study was a placebo-controlled, randomized trial that employed a 2 x 2 factorial design. Healthy older men (mean age 65.5 years) received 30 mg betaC or placebo daily throughout the 47-day trial, while on a low carotenoid diet. After 28 days, half of each group received 12 suberythemic exposures to UV over a 16-day period. Delayed-type hypersensitivity (DTH) tests and plasma carotenoid assays were performed at baseline, pre-UV and post-UV time points, with DTH testing performed on an area of skin protected from UV exposure. RESULTS: UV exposure resulted in significantly suppressed DTH response in the placebo group but not in the betaC-UV group. While there was no significant interaction between betaC supplementation and UV on DTH response, there was a significant inverse relationship between final plasma betaC concentration and extent of UV-induced suppression of DTH response. A similar correlation existed among subjects not exposed to UV. CONCLUSIONS: Suberythemic UV exposure was immunosuppressive, as measured by DTH response, in healthy older men as in younger men. Higher plasma betaC was significantly associated with maintenance of DTH response, although the extent of protective effect of betaC appeared less than previously observed in younger subjects. The attenuated effect of betaC in the older UV-exposed subjects may have resulted in part from muted plasma betaC responses to betaC supplementation and/or higher plasma vitamin E levels than those of younger men. The finding that stronger DTH responses were associated with higher plasma betaC concentrations in both UV and non-UV subjects further supports a role for this nutrient in immunomodulation.

The structure of mitochondrial DNA from the liverwort, Marchantia polymorpha.

The structure of mitochondrial DNA (mtDNA) from cultured cells of the liverwort, Marchantia polymorpha, was analyzed by pulsed-field gel electrophoresis (PFGE) and moving pictures of the fluorescently labeled molecules. Previous electron microscopic analysis with this liverwort revealed a unique property among land plants: mtDNA circles of only one size, that of the 186 kb genome, with no subgenomic circles. Most of the mtDNA was immobile in PFGE and contained complex structures, larger than the genome size with a bright fluorescent node and multiple attached fibers. The mobile mtDNA was mostly linear molecules in monomeric to pentameric lengths of the unit genome that increased following mung bean nuclease digestion, with a corresponding decrease in the immobile fraction. From 0 to 5% of the mtDNA was found as circular molecules the size of the genome and its oligomers; no subgenome-sized circles were present. Radiolabeling revealed that mtDNA synthesis began soon after transfer of cells to fresh medium and most newly replicated mtDNA was immobile; the circular form of the genome was not rapidly labeled.

Use of multivitamin/mineral prenatal supplements: influence on the outcome of pregnancy.

The objective of this study was to examine the association of prenatal multivitamin/mineral supplement use during the first and second trimesters of pregnancy by low income, urban women in the Camden Study (1985-1995, n = 1,430) and preterm delivery (< 37 completed weeks) and infant low birth weight (< 2,500 g). Prenatal supplement use was corroborated by assay of circulating micronutrients at entry to care (no differences) and week 28 gestation (increased concentrations of folate and ferritin for supplement users). Compared with women who entered care during the first or second trimester but did not use prenatal supplements, supplement use starting in the first or second trimester was associated with approximately a twofold reduction in risk of preterm delivery. After controlling for potential confounding variables, risk of very preterm delivery (< 33 weeks' gestation) was reduced more than fourfold for first trimester users and approximately twofold when use dated from the second trimester. Infant low birth weight and very low birth weight (< 1,500 g) risks were also reduced. Risk of low birth weight was reduced approximately twofold with supplement use during the first and second trimester. Diminution in risk was greater for very low birth weight infants, amounting to a sevenfold reduction in risk of very low birth weight with first trimester supplementation and a greater than sixfold reduction when supplement use started in the second trimester. Thus, in low income, urban women, use of prenatal multivitamin/mineral supplements may have the potential to diminish infant morbidity and mortality.

Potential health economic benefits of vitamin supplementation.

This study used published relative risk estimates for birth defects, premature birth, and coronary heart disease associated with vitamin intake to project potential annual cost reductions in U.S. hospitalization charges. Epidemiological and intervention studies with relative risk estimates were identified via MEDLINE. Preventable fraction estimates were derived from data on the percentage of at-risk Americans with daily vitamin intake levels lower than those associated with disease risk reduction. Hospitalization rates were obtained from the 1992 National Hospital Discharge Survey. Charge data from the 1993 California Hospital Discharge Survey were adjusted to 1995 national charges using the medical component of the Consumer Price Index. Based on published risk reductions, annual hospital charges for birth defects, low-birth-weight premature births, and coronary heart disease could be reduced by about 40, 60, and 38%, respectively. For the conditions studied, nearly $20 billion in hospital charges were potentially avoidable with daily use of folic acid and zinc-containing multivitamins by all women of childbearing age and daily vitamin E supplementation by those over 50.

Serum concentrations of alpha tocopherol, beta carotene, and retinol preceding the diagnosis of rheumatoid arthritis and systemic lupus erythematosus.

OBJECTIVES: Because oxidative damage has been implicated in the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus, this study was designed to see if serum concentrations of alpha tocopherol, beta carotene, and retinol, substances believed to be involved in the prevention or repair of oxidative damage, might be lower among persons who develop rheumatoid arthritis or systemic lupus erythematosus than among those who do not. METHODS: For this prospective case-control study, persons with rheumatoid arthritis and systemic lupus erythematosus that developed two to 15 years after donating blood for a serum bank in 1974 were designated as cases. For each case, four controls were selected from the serum bank donors, matched for race, sex, and age. Stored serum samples from cases and controls were assayed for alpha tocopherol, beta carotene, and retinol. RESULTS: Cases of both diseases had lower serum concentrations of alpha tocopherol, beta carotene, and retinol in 1974 than their matched controls. For rheumatoid arthritis, the difference for beta carotene (-29%) was statistically significant. CONCLUSIONS: These findings support those of a previous study that low antioxidant status is a risk factor for rheumatoid arthritis. They suggest a similar association for systemic lupus erythematosus.

Vitamin E and human health: rationale for determining recommended intake levels.

The recent literature provides strong evidence that vitamin E intakes much higher than the current recommendations can contribute to and/or improve human health. In fact, the available data indicate that at higher-than-current recommended intake levels, vitamin E affects several functions related to human health. For example, Vitamin E is required to protect polyunsaturated fatty acids (PUFAs) against auto-oxidation. The amount of vitamin E needed to protect PUFAs against oxidative damage is at least 0.4-0.8 mg vitamin E per gram PUFAs and may be in excess of 1.5 mg/g when diets contain higher-than-average levels of long-chain PUFAs. Based upon studies of vitamin E kinetics and metabolism, a daily vitamin E intake of 135-150 IU is suggested. Important functions such as protection against oxidative damage, immune response, and the propensity of platelets to adhere to the vessel wall are related to vitamin E intakes. Vitamin E intake of 40 IU/d was the least amount demonstrated to inhibit low-density lipoprotein oxidation; a dose-dependent effect was seen up to 800 IU/d. Vitamin E intakes of at least 60 IU/d enhanced immune responses and intakes of 200 IU-400 IU/d decreased platelet adhesion to the vessel wall. Based upon the effects of modulating these functions, it is hypothesized that vitamin E plays a pivotal role in the prevention of cardiovascular diseases. Indeed, many observational studies have reported vitamin E to reduce the risk of cardiovascular disease. Recent intervention studies corroborate these findings. Of equal importance, there is a solid body of literature that demonstrates that these and much higher vitamin E intakes are safe.

The bacterial nucleoid visualized by fluorescence microscopy of cells lysed within agarose: comparison of Escherichia coli and spirochetes of the genus Borrelia.

The nucleoids of Escherichia coli and the spirochetes Borrelia burgdorferi and Borrelia hermsii, agents of Lyme disease and relapsing fever, were examined by epifluorescence microscopy of bacterial cells embedded in agarose and lysed in situ with detergent and protease. The typical E. coli nucleoid was a rosette in which 20 to 50 long loops of DNA emanated from a dense node of DNA. The percentages of cells in a population having nucleoids with zero, one, two, and three nodes varied with growth rate and growth phase. The borrelia nucleoid, in contrast, was a loose network of DNA strands devoid of nodes. This nucleoid structure difference correlates with the unusual genome of Borrelia species, which consists primarily of linear replicons, including a 950-kb linear chromosome and linear plasmids. This method provides a simple, direct means to analyze the structure of the bacterial nucleoid.