Impacts of increased ocean temperatures on a low-latitude coral reef fish - Processes related to oxygen uptake and delivery

Increasing temperatures are expected to significantly affect the physiological performance of ectotherms, particularly in tropical locations. The shape of an organism's thermal reaction norm can provide important information on its capacity to persist under climate change scenarios; however, difficulty lies in choosing a measurable trait that best depicts physiological performance. This study investigated the effects of elevated temperatures on processes related to oxygen uptake and delivery, including oxygen consumption, haematology, and tissue health for a low-latitude population of coral reef damselfish. Acanthochromis polyacanthus were collected from the Torres Strait (10°31-46'S, 142°20-35'E) and maintained at current average ocean temperatures (+0 °C; seasonally cycling), + 1.5 °C and + 3 °C higher than present day temperatures for 10 months. Aerobic performance indicated a limit to metabolic function at + 3 °C (33 °C), following an increase in aerobic capacity at + 1.5 °C (31.5 °C). Neither haematological parameters nor gill morphology showed the same improvement in performance at + 1.5 °C. Gill histopathology provided the first indicator of a decline in organism health, which corresponded with mortality observations from previous research. Findings from this study suggest thermal specialisation in this low-latitude population as well as variation in thermal sensitivity, depending on the physiological trait.

Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials

A systematic review and meta-analysis of randomized controlled trials was conducted to examine the effects of probiotic supplementation on body weight, body mass index (BMI), fat mass and fat percentage in subjects with overweight (BMI 25-29.9 kg m^-2 ) or obesity (BMI ≥30 kg m^-2 ). MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched for studies published between 1946 and September 2016. A meta-analysis, using a random effects model, was performed to calculate the weighted mean difference between the intervention and control groups. Of 800 studies identified through the literature search, 15 were finally included. The studies comprised a total of 957 subjects (63% women), with the mean BMI being 27.6 kg m^-2 and the duration of the interventions ranging from 3 to 12 weeks. Administration of probiotics resulted in a significantly larger reduction in body weight (weighted mean difference [95% confidence interval]; -0.60 [-1.19, -0.01] kg, I²  = 49%), BMI (-0.27 [-0.45, -0.08] kg m^-2 , I²  = 57%) and fat percentage (-0.60 [-1.20, -0.01] %, I²  = 19%), compared with placebo; however, the effect sizes were small. The effect of probiotics on fat mass was non-significant (-0.42 [-1.08, 0.23] kg, I²  = 84%).

Treatment with methylnaltrexone is associated with increased survival in patients with advanced cancer

BACKGROUND

Methylnaltrexone (MNTX), a peripherally acting μ-opioid receptor (MOR) antagonist, is FDA-approved for treatment of opioid-induced constipation (OIC). Preclinical data suggest that MOR activation can play a role in cancer progression and can be a target for anticancer therapy.

PATIENTS AND METHODS

Pooled data from advanced end-stage cancer patients with OIC, despite laxatives, treated in two randomized (phase III and IV), placebo-controlled trials with MNTX were analyzed for overall survival (OS) in an unplanned post hoc analysis. MNTX or placebo was given subcutaneously during the double-blinded phase, which was followed by the open-label phase, allowing MNTX treatment irrespective of initial randomization.

RESULTS

In two randomized, controlled trials, 229 cancer patients were randomized to MNTX (117, 51%) or placebo (112, 49%). Distribution of patients' characteristics and major tumor types did not significantly differ between arms. Treatment with MNTX compared with placebo [76 days, 95% confidence interval (CI) 43-109 versus 56 days, 95% CI 43-69; P = 0.033] and response (laxation) to treatment compared with no response (118 days, 95% CI 59-177 versus 55 days, 95% CI 40-70; P < 0.001) had a longer median OS, despite 56 (50%) of 112 patients ultimately crossing over from placebo to MNTX. Multivariable analysis demonstrated that response to therapy [hazard ratio (HR) 0.47, 95% CI 0.29-0.76; P = 0.002) and albumin ≥3.5 (HR 0.46, 95% CI 0.30-0.69; P < 0.001) were independent prognostic factors for increased OS. Of interest, there was no difference in OS between MNTX and placebo in 134 patients with advanced illness other than cancer treated in these randomized studies (P = 0.88).

CONCLUSION

This unplanned post hoc analysis of two randomized trials demonstrates that treatment with MNTX and, even more so, response to MNTX are associated with increased OS, which supports the preclinical hypothesis that MOR can play a role in cancer progression. Targeting MOR with MNTX warrants further investigation in cancer therapy.

CLINICAL TRIALS NUMBER

NCT00401362, NCT00672477.

Metabolic Evidence of Diminished Lipid Oxidation in Women With Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS), a common female endocrinopathy, is a complex metabolic syndrome of enhanced weight gain. The goal of this pilot study was to evaluate metabolic differences between normal (n=10) and PCOS (n=10) women via breath carbon isotope ratio, urinary nitrogen and nuclear magnetic resonance (NMR)-determined serum metabolites. Breath carbon stable isotopes measured by cavity ring down spectroscopy (CRDS) indicated diminished (p<0.030) lipid use as a metabolic substrate during overnight fasting in PCOS compared to normal women. Accompanying urinary analyses showed a trending correlation (p<0.057) between overnight total nitrogen and circulating testosterone in PCOS women, alone. Serum analyzed by NMR spectroscopy following overnight, fast and at 2 h following an oral glucose tolerance test showed that a transient elevation in blood glucose levels decreased circulating levels of lipid, glucose and amino acid metabolic intermediates (acetone, 2-oxocaporate, 2-aminobutyrate, pyruvate, formate, and sarcosine) in PCOS women, whereas the 2 h glucose challenge led to increases in the same intermediates in normal women. These pilot data suggest that PCOS-related inflexibility in fasting-related switching between lipid and carbohydrate/protein utilization for carbon metabolism may contribute to enhanced weight gain.

Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans

Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool for individuals attempting weight loss. As a proof of concept, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath δ(13)C) reflects shifts between negative and positive energy balance. Volunteers (n=5) consumed a 40% energy-restricted diet for 6 days followed by 50% excess on day 7. Breath was sampled immediately before and 1 h and 2 h after breakfast, lunch and dinner. Exhaled breath δ(13)C values were measured by cavity ring-down spectroscopy. Using repeated measures analysis of variance (ANOVA) followed by Dunnett's contrasts, pre-breakfast breath values on days 2-6 were compared with day 1, and postprandial day 7 time points were compared with pre-breakfast day 7. Energy restriction diminished pre-breakfast breath δ(13)C by day 3 (P<0.05). On day 7, increased energy intake was first detected immediately before dinner (-23.8±0.6 vs -21.9±0.7‰, P=0.002 (means±s.d.)), and breath δ(13)C remained elevated at least 2 h post dinner. In conclusion, when shifting between negative and positive energy balance, breath δ(13)C showed anticipated isotopic changes. Although additional research is needed to determine specificity and repeatability, this method may provide a biomarker for marked increases in caloric intake.

Nerol: An alarm substance of the stingless bee,Trigona fulviventris (Hymenoptera: Apidae)

Bees of the genusTrigona and subgenusTrigona possess volatile materials in their mandibular glands, used as alarm substances and as marking pheromones. Heads of workers ofTrigona fulviventris were analyzed by gas chromatography-mass spectrometry. The two major volatile components were nerol (∼ 50%), and octyl caproate (∼ 20%). Relative to other substances tested at a Costa Rican nest, treatments containing 20 μg of nerol attractedT. fulviventris, depressed numbers of bees leaving the nest by about 50%, and elicited wing vibration and biting. The responses were similar to those obtained with the contents of one worker head. Attraction and biting were also seen in response to captures of colony members by assassin bugs (Apiomerus pictipes) outside a nest entrance; one bee responded in about 15% of the captures. This alarm behavior, although weak, is of interest since it was thought thatT. fulviventris was unusual for its subgenus in its lack of nest defense behaviors.

Alarm substances of the stingless bee,Trigona silvestriana

2-Nonanol, 2-heptanol, octyl decanoate, and octyl octanoate were identified from the heads ofTrigona silvestriana workers. When presented at the nest, 2-nonanol, 2-heptanol, and the mixture of the four compounds elicited angular flights, landing, and buzzing of guard bees. Octyl octanoate elicited a weaker response. No response was given to octyl decanoate, to the ether solvent, or to the control volatile, vanillin.

Transformation by Hras(G12V) is consistently associated with mutant allele copy gains and is reversed by farnesyl transferase inhibition

RAS-driven malignancies remain a major therapeutic challenge. The two-stage 7,12-dimethylbenz(a)anthracene (DMBA)/12-o-tetradecanoylphorbol-13-acetate (TPA) model of mouse skin carcinogenesis has been used to study mechanisms of epithelial tumor development by oncogenic Hras. We used mice with a Hras^G12V knock-in allele to elucidate the early events after Hras activation, and to evaluate the therapeutic effectiveness of farnesyltransferase (FTI) inhibition. Treatment of Caggs-Cre/FR-Hras^G12V mice with TPA alone was sufficient to trigger papilloma development with shorter latency and a ~10-fold greater tumor burden than DMBA/TPA-treated WT controls. Hras^G12V allele copy number was increased in all papillomas induced by TPA. DMBA/TPA treatment of Hras^G12V knock-in mice induced an even greater incidence of papillomas, which either harbored Hras^G12V amplification, or developed a Hras^Q61L mutation in the second allele. Laser-capture microdissection of normal skin, hyperplastic skin and papillomas showed that amplification occurred only at the papilloma stage. HRAS mutant allelic imbalance was also observed in human cancer cell lines, consistent with a requirement for augmented oncogenic HRAS signaling for tumor development. The FTI SCH66336 blocks HRAS farnesylation and delocalizes it from the plasma membrane. NRAS and KRAS are not affected as they are alternatively prenylated. When tested in lines harboring HRAS, NRAS or KRAS mutations, SCH66336 delocalized, inhibited signaling and preferentially inhibited growth only of HRAS-mutant lines. Treatment with SCH66336 also induced near-complete regression of papillomas of TPA-treated Hras^G12V knock-in mice. These data suggest that farnesyl transferase inhibitors should be reevaluated as targeted agents for human HRAS-driven cancers, such as those of bladder, thyroid and other epithelial lineages.

Prenatal low-protein and postnatal high-fat diets induce rapid adipose tissue growth by inducing Igf2 expression in Sprague Dawley rat offspring

Maternal low-protein diets result in lower birth weight followed by accelerated catch-up growth that is accompanied by the development of obesity and glucose intolerance in later life. Whether postnatal high-fat (HF) diets further contribute to the development of obesity and insulin resistance in offspring by affecting adipose tissue metabolism and DNA methylation is currently unknown. Obese-prone Sprague-Dawley rats were fed 8% low protein (LP) or 20% normal protein diets for 3 wk prior to conception and throughout pregnancy and lactation to investigate whether prenatal LP and postnatal HF diets affect the rate of adipose tissue growth, insulin-like growth factor 2 (Igf2) expression, and DNA methylation in male offspring. At weaning, the offspring were fed 10% normal fat or 45% HF diets for 12 wk. The adipose tissue growth rate was increased (up to 26-fold) by the LP prenatal and HF postnatal diets. Adipose tissue Igf2 mRNAs and DNA methylation were increased by the LP prenatal and HF postnatal diets. The LP prenatal and HF postnatal diet increased the number of small adipocytes in adipose tissue and decreased insulin sensitivity. These findings suggest that prenatal LP and postnatal HF intake result in adipose tissue catch-up growth through alterations in the expression of the Igf2 gene and DNA methylation within adipocytes. These alterations in adiposity are accompanied by an increased risk of development of type 2 diabetes.

Arterial stiffness, lifestyle intervention and a low-calorie diet in morbidly obese patients-a nonrandomized clinical trial

OBJECTIVE

Arterial stiffness is an independent predictor of cardiovascular morbidity and mortality. This study aimed to compare the 7-week effect of a low-calorie diet (LCD) and an intensive lifestyle intervention program (ILI) on arterial stiffness in morbidly obese individuals.

DESIGN AND METHODS

Nonrandomized clinical trial. The LCD provided 900 kcal/day, and participants in the LCD group were instructed to maintain their habitual physical activity level. The ILI included two 90-min supervised training sessions 3 days a week at moderate to high intensity (4-8 METs) and a caloric restriction of 1000 kcal/day.

RESULTS

A total of 179 individuals completed the study, 88 (56 women) in the ILI group and 91 (57 women) in the LCD group. High-fidelity applanation tonometry (Millar(®) , Sphygmocor(®) ) was used to measure carotid-femoral pulse wave velocity (PWV). After adjustment for relevant confounders, the ILI group had a significantly greater reduction in PWV than the LCD group; -0.4 (-0.6, -0.1) m/s, P = 0.004. When compared to the LCD group, the ILI group showed a larger reduction in systolic and diastolic blood pressure -5 (-9, -1) and -5 (-7, -2) mmHg, P = 0.038 and P ≤ 0.001 respectively, whereas no difference was observed regarding pulse pressure, P = 0.661. No significant differences between groups were found regarding the loss of fat mass, P = 0.259, but the loss of muscle mass was larger in the LCD group, 0.8 (0.5, 1.1) kg, P ≤ 0.001.

CONCLUSION

Despite the limitations of a nonrandomized design, our findings indicate that for morbidly obese individuals a moderate caloric restriction combined with aerobic physical exercise is associated with a greater decline in PWV than a LCD alone.

Methylselenol, a selenium metabolite, modulates p53 pathway and inhibits the growth of colon cancer xenografts in Balb/c mice

It is has been hypothesized that methylselenol is a critical selenium metabolite for anticancer activity in vivo. In this study, we used a protein array which contained 112 different antibodies known to be involved in the p53 pathway to investigate the molecular targets of methylselenol in human HCT116 colon cancer cells. The array analysis indicated that methylselenol exposure changed the expression of 11 protein targets related to the regulation of cell cycle and apoptosis. Subsequently, we confirmed these proteins with the Western blotting approach, and found that methylselenol increased the expression of GADD 153 and p21 but reduced the level of c-Myc, E2F1 and Phos p38 MAP kinase. Similar to our previous report on human HCT116 colon cancer cells, methylselenol also inhibited cell growth and led to an increase in G1 and G2 fractions with a concomitant drop in S-phase in mouse colon cancer MC26 cells. When the MC26 cells were transplanted to their immune-competent Balb/c mice, methylselenol-treated MC26 cells had significantly less tumor growth potential than that of untreated MC26 cells. Taken together, our data suggest that methylselenol modulates the expression of key genes related to cell cycle and apoptosis and inhibits colon cancer cell proliferation and tumor growth.

Effect of clothing weight on body weight

BACKGROUND

In clinical settings, it is common to measure weight of clothed patients and estimate a correction for the weight of clothing, but we can find no papers in the medical literature regarding the variability in clothing weight of adults with weather, season and gender.

METHODS

Fifty adults (35 women) were weighed four times during a 12-month period with and without clothing. Clothing weights were determined and regressed against minimum, maximum and average daily outdoor temperature.

RESULTS

The average clothing weight (±s.d.) throughout the year was significantly greater in men than in women (1.2±0.3 vs 0.8±0.3 kg, P<0.0001). The average within-person minimum and the average within-person maximum clothing weights across the year were 0.9±0.2 and 1.5±0.4 kg for men, and 0.5±0.2 and 1.1±0.4 kg for women, respectively. The within-person s.d. in clothing weight was 0.3 kg for both men and women. Over the 55 °C range in the lowest to the highest outdoor temperatures, the regressions predicted a maximal change in clothing weight of only 0.4 kg in women and 0.6 kg in men.

CONCLUSION

The clothing weight of men is significantly greater than that of women, but there is little variability throughout the year. Therefore, a clothing adjustment of approximately 0.8 kg for women and 1.2 kg for men is appropriate regardless of outdoor temperature.

Obesity-related cardiovascular risk factors after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention

OBJECTIVE

Weight reduction improves several obesity-related health conditions. We aimed to compare the effect of bariatric surgery and comprehensive lifestyle intervention on type 2 diabetes and obesity-related cardiovascular risk factors.

DESIGN

One-year controlled clinical trial (ClinicalTrials.gov identifier NCT00273104).

METHODS

Morbidly obese subjects (19-66 years, mean (s.d.) body mass index 45.1 kg/m(2) (5.6), 103 women) were treated with either Roux-en-Y gastric bypass surgery (n=80) or intensive lifestyle intervention at a rehabilitation centre (n=66). The dropout rate within both groups was 5%.

RESULTS

Among the 76 completers in the surgery group and the 63 completers in the lifestyle group, mean (s.d.) 1-year weight loss was 30% (8) and 8% (9) respectively. Beneficial effects on glucose metabolism, blood pressure, lipids and low-grade inflammation were observed in both groups. Remission rates of type 2 diabetes and hypertension were significantly higher in the surgery group than the lifestyle intervention group; 70 vs 33%, P=0.027, and 49 vs 23%, P=0.016. The improvements in glycaemic control and blood pressure were mediated by weight reduction. The surgery group experienced a significantly greater reduction in the prevalence of metabolic syndrome, albuminuria and electrocardiographic left ventricular hypertrophy than the lifestyle group. Gastrointestinal symptoms and symptomatic postprandial hypoglycaemia developed more frequently after gastric bypass surgery than after lifestyle intervention. There were no deaths.

CONCLUSIONS

Type 2 diabetes and obesity-related cardiovascular risk factors were improved after both treatment strategies. However, the improvements were greatest in those patients treated with gastric bypass surgery.

Dietary protein and calcium interact to influence calcium retention: a controlled feeding study

BACKGROUND

The effect of meat protein on calcium retention at different calcium intakes is unresolved.

OBJECTIVE

The objective was to test the effect of dietary protein on calcium retention at low and high intakes of calcium.

DESIGN

In a randomized controlled feeding study with a 2 x 2 factorial crossover design, healthy postmenopausal women (n = 27) consumed either approximately 675 or approximately 1510 mg Ca/d, with both low and high protein (providing 10% and 20% energy) for 7 wk each, separated by a 3-wk washout period. After 3 wk, the entire diet was extrinsically labeled with (47)Ca, and isotope retention was monitored by whole-body scintillation counting. Clinical markers of calcium and bone metabolism were measured.

RESULTS

High compared with low dietary protein significantly increased calcium retention from the low-calcium (29.5% compared with 26.0% absorbed) but not the high-calcium diet (18% absorbed). For the low-calcium diet, this effect nearly balanced a protein-related 0.5-mmol/d greater urinary calcium excretion. Protein-related calciuretic effects were independent of dietary calcium. Testing at 1, 2, 3, 5, and 7 wk showed no long-term adaptation in urinary acidity or urinary calcium excretion. High compared with low dietary protein decreased urinary deoxypyridinoline and increased serum insulin-like growth factor I without affecting parathyroid hormone, osteocalcin, bone-specific alkaline phosphatase, or tartrate-resistant acid phosphatase.

CONCLUSIONS

In healthy postmenopausal women, a moderate increase in dietary protein, from 10% to 20% of energy, slightly improved calcium absorption from a low-calcium diet, nearly compensating for a slight increase in urinary calcium excretion. Under practical dietary conditions, increased dietary protein from animal sources was not detrimental to calcium balance or short-term indicators of bone health.

Histological observations of bovine tuberculosis in lung and lymph node tissues from British deer

Deer are recognized as hosts of Mycobacterium bovis and assessing the role of wild cervids in perpetuating tuberculosis among cattle has motivated extensive research on several continents. In this paper, the histopathology of lymph node and lung tuberculous granulomas in M. bovis positive British deer is presented. The overall aim was to seek further insights into the potential for onward transmission from infected deer to other species, including cattle. Samples were obtained from an extensive survey of wild mammals in South-West England and from statutory tuberculosis surveillance. M. bovis culture-positive samples were characterised microscopically as to their stage of lesion advancement, number of acid-fast bacilli and granuloma encapsulation. Seventy percent of the deer developed granulomas containing far greater numbers of M. bovis bacilli than typically reported in cattle. Red and fallow deer had the largest number of poorly encapsulated granulomas often containing many hundreds of bacilli. The results are consistent with infected wild British deer being a potential source of environmental contamination and onward transmission to other species. However, further work on levels of bacillary shedding is required before this can be confirmed.

A selenium-deficient Caco-2 cell model for assessing differential incorporation of chemical or food selenium into glutathione peroxidase

Assessing the ability of a selenium (Se) sample to induce cellular glutathione peroxidase (GPx) activity in Se-deficient animals is the most commonly used method to determine Se bioavailability. Our goal is to establish a Se-deficient cell culture model with differential incorporation of Se chemical forms into GPx, which may complement the in vivo studies. In the present study, we developed a Se-deficient Caco-2 cell model with a serum gradual reduction method. It is well recognized that selenomethionine (SeMet) is the major nutritional source of Se; therefore, SeMet, selenite, or methylselenocysteine (SeMSC) was added to cell culture media with different concentrations and treatment time points. We found that selenite and SeMSC induced GPx more rapidly than SeMet. However, SeMet was better retained as it is incorporated into proteins in place of methionine; compared with 8-, 24-, or 48-h treatment, 72-h Se treatment was a more sensitive time point to measure the potential of GPx induction in all tested concentrations. Based on induction of GPx activity, the cellular bioavailability of Se from an extract of selenobroccoli after a simulated gastrointestinal digestion was comparable with that of SeMSC and SeMet. These in vitro data are, for the first time, consistent with previous published data regarding selenite and SeMet bioavailability in animal models and Se chemical speciation studies with broccoli. Thus, Se-deficient Caco-2 cell model with differential incorporation of chemical or food forms of Se into GPx provides a new tool to study the cellular mechanisms of Se bioavailability.

Calcium requirements: new estimations for men and women by cross-sectional statistical analyses of calcium balance data from metabolic studies

BACKGROUND

Low intakes of calcium are associated with an increased risk of both osteoporosis and cardiovascular disease.

OBJECTIVE

To provide new estimates of the average calcium requirement for men and women, we determined the dietary calcium intake required to maintain neutral calcium balance.

DESIGN

Calcium balance data [calcium intake -(fecal calcium + urinary calcium)] were collected from 155 subjects [women: n = 73; weight: 77.1 +/- 18.5 kg; age: 47.0 +/- 18.5 y (range: 20-75 y); men: n = 82; weight: 76.6 +/- 12.5 kg; age: 28.2 +/- 7.7 y (range: 19-64 y)] who participated in 19 feeding studies conducted in a metabolic unit. Balance data from the final 6-12 d of each dietary period (minimum length:18 d) of each study (1-9 observations per subject) were analyzed. Data were excluded if individual intakes of magnesium, copper, iron, phosphorus, or zinc fell below the estimated average requirements or exceeded the 99 th percentile of usual intakes from the 1994 Continuing Survey of Food Intakes by Individuals (for iron, above the upper limit). Daily intakes of calcium ranged between 415 and 1740 mg. The relation between intake and output was examined by fitting random coefficient models. Coefficients were included to test for sex and age differences.

RESULTS

The models predicted a neutral calcium balance [defined as calcium output (Y) equal to calcium intake (C)] at intakes of 741 mg/d [95% prediction interval (PI): 507, 1035; Y = 148.29 + 0.80C], 9.4 mg kg body wt(-1) d(-1) [95% PI: 6.4, 12.9; Y = 1.44 + 0.85C], or 0.28 mg kcal(-1) d(-1) [95% PI: 0.19, 0.38; Y = 0.051 + 0.816C]. Neither age nor sex affected the estimates when calcium intakes were expressed as mg/d or as mg kg body wt(-1) d(-1).

CONCLUSION

The findings suggest that the calcium requirement for men and women is lower than previously estimated.

Scanning optical pyrometer for measuring temperatures in hollow cathodes

Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measurements of the external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. The diagnostic method and initial measurements of the temperature distribution in a hollow cathode are discussed.

Determination of selenium bioavailability from wheat mill fractions in rats by using the slope-ratio assay and a modified torula yeast-based diet

Selenium is an essential mineral micronutrient for animals, and significant evidence supports an association between supranutritional Se intake and a reduction in the incidence of some forms of cancer. Thus, supplemental Se intake may provide an avenue for reducing cancer incidence. However, an important issue to consider is the form of Se that should be provided in such a supplement, because the bioavailability and bioactivity of Se can vary dramatically depending on the chemical form in which it is delivered. Because wheat products are the largest source of Se in U.S. diets, the absorption of Se was evaluated in different fractions of milled wheat that exhibits very high Se levels, owing to its production on naturally Se-rich soils. An experiment was conducted to determine the bioavailability of Se from three milled fractions of high-Se wheat. The method used was the slope-ratio assay, which measures the ability of Se from the wheat fractions to regenerate Se-dependent enzyme activities and tissue Se concentrations in Se-deficient rats. The responses generated from wheat Se were compared to a standard response curve generated by feeding graded amounts of Se as sodium selenite (Na2SeO3; NaSelenite) or selenomethionine (SeMet) in an AIN-93G-Torula yeast-based diet. Results showed that Se from wheat flour ( approximately 75% extraction) was nearly 100% available by a number of measures including plasma, liver, kidney, and muscle Se concentrations and liver and erythrocyte Se-dependent enzyme activities when compared with similar measures in rats fed NaSelenite or SeMet. However, on the basis of similar criteria, Se from wheat shorts was only about 85% available and that from wheat bran was about 60% available for absorption. These results indicate that high-Se wheat products, mainly those made from refined flour alone, might be particularly well suited for use as dietary Se supplements.

Pinto beans are a source of highly bioavailable copper in rats

The trace element copper (Cu) is a required nutrient in the diets of humans. It has been found in animal studies to be essential for efficient iron absorption and oxygen utilization and for aiding free-radical degradation. Dry beans (Phaseolis vulgaris) are potentially good sources of Cu; thus, the objective of this study was to determine the bioavailability of Cu from dry beans using the pinto bean as the source. Dry beans were obtained from a local market, cooked according to package directions, and dried. Weanling male Sprague-Dawley rats (8 groups of 8 rats each) were fed a Cu-deficient diet (AIN-93G) for 4 wk followed by 2 wk of Cu repletion with diets containing 0-6.5 mg Cu/kg diet added as CuSO(4) or with 0.6 and 1.5 mg Cu/kg incorporated into rat diets as pinto beans at 10 and 20%. Standard response curves were developed based on repletion-induced recovery of 10 indices of Cu status, including organ Cu concentrations and Cu-dependent enzyme activities, in response to increasing dietary Cu as CuSO(4). Recovery of these variables in rats fed the pinto bean diets was compared with the standard response curve at similar levels of dietary Cu. Based on the recovery of all 10 variables, the relative bioavailability of Cu from dry beans was at least 100% of that with the highly available CuSO(4). For 3 of the variables, liver and heart Cu concentrations and serum superoxide dismutase 3 activity, estimated bioavailability values of Cu from beans were 138, 140, and 134%, respectively, of those from CuSO(4). We conclude that the dry pinto bean is a good source of dietary Cu with respect to both concentration and bioavailability.

Magnesium requirements: new estimations for men and women by cross-sectional statistical analyses of metabolic magnesium balance data

BACKGROUND

Current recommendations for magnesium requirements are based on sparse balance data.

OBJECTIVE

To provide new estimates of the average magnesium requirement for men and women, we pooled magnesium data from 27 different tightly controlled balance studies conducted at the US Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND.

DESIGN

Magnesium balance data (magnesium intake - [fecal magnesium + urinary magnesium]) (664 data points) were collected from 243 subjects (women: n = 150; weight: 71.6 +/- 16.5 kg; age: 51.3 +/- 17.4 y; men: n = 93, weight: 76.3 +/- 12.5 kg; age: 28.1 +/- 8.1 y). Data from the last 6-14 d of each dietary period (> or =28 d) of each study were analyzed and were excluded if individual intakes of calcium, copper, iron, phosphorus, or zinc fell below respective estimated average requirements (EARs) or exceeded 99th percentiles of usual intakes of those elements (iron: above the upper limit) from the 1994 Continuing Survey of Food Intakes by Individuals. Daily intakes of magnesium ranged between 84 and 598 mg. The relation between magnesium intake and magnesium output was investigated by fitting random coefficient models.

RESULTS

The models predicted neutral magnesium balance [defined as magnesium output (Y) equal to magnesium intake (M)] at magnesium intakes of 165 mg/d [95% prediction interval (PI): 113, 237 mg/d; Y = 19.8 + 0.880 M], 2.36 mg . kg(-1) . d(-1) (95% PI: 1.58, 3.38 mg . kg(-1) . d(-1); Y = 0.306 + 0.870 M), or 0.075 mg . kcal(-1) . d(-1) (95% PI: 0.05, 0.11 mg . kcal(-1) . d(-1); Y = 0.011 + 0.857 M). Neither age nor sex affected the relation between magnesium intake and output.

CONCLUSION

The findings suggest a lower magnesium requirement for healthy men and women than estimated previously.

Selenium bioavailability from buckwheat bran in rats fed a modified AIN-93G torula yeast-based diet

Selenium (Se) is an essential nutrient for humans and animals. The Se RDA for adult humans is 55 mug/d; however, dietary amounts as high as 200 mug/d in the highly available form of selenomethionine in yeast were shown to reduce the incidence of certain cancers. A number of natural foods contain relatively high amounts of Se; for the most part, however, the availability of food Se for absorption and utilization is unknown. This experiment was conducted to determine the bioavailability of Se from a high-protein, high-fiber bran-isolate of buckwheat groats that contains Se. The method used was based on the ability of Se from buckwheat bran to restore Se-dependent enzyme activities and tissue Se concentrations in Se-deficient rats. The responses produced from buckwheat bran Se were compared with a standard response curve generated by feeding graded amounts of Se as sodium selenite (Na(2)SeO(3); Na selenite) or selenomethionine (SeMet) in a newly reformulated AIN-93G-Torula yeast diet with a more balanced nutrient composition than older diets of this nature. Relative bioavailability was determined by using the slope-ratio assay method for enzyme data, or the parallel lines assay method for tissue Se concentration data. Results showed that Se availability from buckwheat bran based on the restoration of plasma Se was 70-80% as high as Na selenite or SeMet. However, when based on the restoration of muscle Se, buckwheat bran was 90% as high as Na selenite, but only 60% as high as SeMet. When using the ability of dietary Se to restore whole blood and liver glutathione peroxidase activity, buckwheat bran Se was 75-80% as high as Na selenite or SeMet. However, for the restoration of liver thioredoxin reductase, buckwheat bran Se was only 40% as high as Na selenite and 70% as high as SeMet. The relative bioavailability of Se from buckwheat bran with all variables considered was approximately 73% whether measured against Na selenite or SeMet. Although some variables indicated low bioavailability of Se from buckwheat bran, other factors such as Se speciation in the bran, digestibility of the bran, the cooking process, and combinations with other foods in the diet should be considered and analyzed before firm conclusions can be reached.

Controlled substitution of soy protein for meat protein: effects on calcium retention, bone, and cardiovascular health indices in postmenopausal women

In a controlled feeding study, the effects of substituting 25 g soy protein for meat on calcium retention and bone biomarkers were determined. Postmenopausal women (n = 13) ate two diets that were similar, except that, in one diet, 25 g high-isoflavone soy protein (SOY) was substituted for an equivalent amount of meat protein (control diet), for 7 wk each in a randomized crossover design. After 3 wk of equilibration, calcium retention was measured by labeling the 2-d menu with (47)Ca, followed by whole-body counting for 28 d. Urinary calcium and renal acid excretion were measured at wk 3, 5, and 7. Biomarkers of bone and cardiovascular health were measured at the beginning and end of each diet. Calcium was similarly retained during the control and SOY diets (d 28, percent dose, mean +/- pooled sd: 14.1 and 14.0 +/- 1.6, respectively). Despite a 15-20% lower renal acid excretion during the SOY diet, urinary calcium loss was unaffected by diet. Diet also did not affect any of the indicators of bone or cardiovascular health. Substitution of 25 g high isoflavone soy protein for meat, in the presence of typical calcium intakes, did not improve or impair calcium retention or indicators of bone and cardiovascular health in postmenopausal women.

Boron concentrations in milk from mothers of full-term and premature infants

BACKGROUND

Boron is a bioactive element that satisfies several of the criteria for essentiality in humans.

OBJECTIVE

The objective was to establish the profile of boron metabolism in human milk.

DESIGN

Lactating mothers of premature (PRT; n = 10, <2000 g birth weight, <37 wk gestation) and full-term (FT; n = 10, >2500 g, 39-41 wk gestation) infants living in St John's, Canada, collected milk samples once a week for 12 wk. Samples were analyzed for boron, copper, iron, selenium, and zinc by atomic emission or absorption spectrometry after wet-ash digestion with nitric acid and hydrogen peroxide in polytetrafluoroethylene tubes.

RESULTS

A mixed-model analysis of variance indicated that boron concentrations were stable in full-term (30 and 28 mug/L milk; P = 0.5) but not in preterm (37 and 27 mug/L; P = 0.01) milk between weeks 1 and 12, respectively. As expected, there were reductions in the concentrations of copper (FT: 651 to 360 mug/L, P < 0.0001; PRT: 542 to 425, P = 0.05), iron (FT: 355 to 225 mug/L, P = 0.0003; PRT: 406 to 287, P = 0.002), selenium (FT: 26.9 to 18.6 mug/L, P < 0.0001; PRT: 28.7 to 20.4, P < 0.0001), and zinc (FT: 4060 to 1190 mug/L, P < 0.0001; PRT: 5970 to 1270, P < 0.0001) over time.

CONCLUSIONS

The stable milk boron concentrations over time suggest that boron may be under homeostatic control. The patterns of change in copper, iron, selenium, and zinc concentrations in milk differ from those of boron. Further research is needed to elucidate the mechanism of milk boron secretion.

Metabolic influences of fiber size in aerobic and anaerobic locomotor muscles of the blue crab, Callinectes sapidus

Diameters of some white locomotor muscle fibers in the adult blue crab, Callinectes sapidus, exceed 500 μm whereas juvenile white fibers are &lt;100 μm. It was hypothesized that aerobically dependent processes,such as metabolic recovery following burst contractions, will be significantly impeded in the large white fibers. In addition, dark aerobic fibers of adults,which rely on aerobic metabolism for both contraction and recovery, grow as large as the white fibers. These large aerobic fibers are subdivided, however,thus decreasing the effective diameter of each metabolic functional unit and enabling aerobic contraction. The two goals of this study were: (1) to characterize the development of subdivisions in the dark levator muscle fibers and (2) to monitor post-contractile metabolism as a function of fiber size in aerobic and anaerobic levator muscles. Dark levator muscle fibers from crabs ranging from &lt;0.1 g to &gt;190 g were examined with transmission electron microscopy to determine the density of mitochondria and subdivision diameters. Across all size classes, there was a constant mitochondrial fractional area(25% of the total subdivision area) and subdivision size (mean diameter of 36.5±2.7 μm). Thus, blue crab dark levator fibers are unusual in having metabolic functional units (subdivisions) that do not increase in size during development while the contractile functional units (fibers) grow hypertrophically. The body mass scaling of post-contractile lactate dynamics was monitored during recovery from anaerobic, burst exercise in white and dark muscle, and in hemolymph. There were no differences among size classes in lactate accumulation during exercise in either muscle. However, in white fibers from large crabs, lactate continued to increase after exercise, and lactate removal from tissues required a much longer period of time relative to smaller crabs. Differences in lactate removal among size classes were less pronounced in dark fibers, and post-contractile lactate accumulation was significantly higher in white than in dark fibers from large animals. These data suggest that the large white fibers invoke anaerobic metabolism following contraction to accelerate certain phases of metabolic recovery that otherwise would be overly slow. This implies that, in addition to the typical mass-specific decrease in oxidative capacity that accompanies increases in animal mass, aerobic metabolic processes become increasingly limited by surface area to volume and intracellular diffusion constraints in developing white muscle fibers.

Granulomatous skin lesions in moray eels caused by a novel Mycobacterium species related to Mycobacterium triplex

An outbreak of granulomatous dermatitis was investigated in a captive population of moray eels. The affected eels had florid skin nodules concentrated around the head and trunk. Histopathological examination revealed extensive granulomatous inflammation within the dermis and subcutaneous fascial plane between the fat and axial musculature. Acid-fast rods were detected within the smallest lesions, which were presumably the ones that had developed earliest. Eventually, after several months of incubation at room temperature, a very slowly growing acid-fast organism was isolated. Sequencing of the 16S rRNA gene identified it as a Mycobacterium species closely related (0.59% divergence) to M. triplex, an SAV mycobacterium. Intradermal inoculation of healthy green moray eels with this organism reliably reproduced the lesion. Experimentally induced granulomatous dermatitis appeared within 2 weeks of inoculation and slowly but progressively expanded during the 2 months of the experiment. Live organisms were recovered from these lesions at all time points, fulfilling Koch's postulates for this bacterium. In a retrospective study of tissues collected between 1993 and 1999 from five spontaneous disease cases, acid-fast rods were consistently found within lesions, and a nested PCR for the rRNA gene also demonstrated the presence of mycobacteria within affected tissues.

[Diet and secondary prevention of coronary heart disease--are our recommendations good enough?]

BACKGROUND

Dietary treatment plays an important role in prevention of coronary heart disease. In Norway as in other European countries, patients with established coronary heart disease are advised to follow a cholesterol-lowering diet. However, epidemiological observations have suggested that Mediterranean and other diets may have cardioprotective characteristics beyond their effects on serum total and LDL cholesterol levels.

MATERIAL AND METHODS

We describe the results of randomised, controlled clinical trials that have investigated the effect of diet on secondary prevention of coronary heart disease.

RESULTS

Diets characterised by high contents of oleic acid (18: 1n-9), alpha-linolenic acid (18: 3n-3) and fish or fish oil and near-vegetarian diets have reduced cardiovascular morbidity and mortality in patients with coronary heart disease.

INTERPRETATION

Several characteristics of the Mediterranean diet seem to have additional anti-atherothrombogenic effects beyond those observed with the usually recommended cholesterol-lowering diet. We ask whether Norwegian dietary recommendations for secondary prevention, should emphasise more strongly the type of fat used and fruit and vegetable intake, in line with the principles of the Mediterranean diet. Such dietary advice should be incorporated into the medical treatment given to all patients with coronary heart disease, regardless of their lipid profile.

Oocyte donor screening: the selection process and cost analysis

OBJECTIVE

To evaluate the selection process and cost of screening oocyte donors.

DESIGN

Retrospective analysis.

SETTING

University-based IVF program.

PATIENT(S)

Potential oocyte donors.

INTERVENTION(S)

Outcomes of all inquiries by individuals responding to recruitment advertisements for oocyte donors over a 10-month period were assessed. Recruitment and screening costs to bring a single donor into the program were calculated.

MAIN OUTCOME MEASURE(S)

The attrition rate for each step of the oocyte donor screening process was determined. The costs assessed over the study period included the following: advertisement, administrative, professional, ultrasound, and blood screening. The total cost to bring a single donor into the program was calculated.

RESULT(S)

Advertisements led to 315 phone inquiries from potential oocyte donors. Of these, a total of 223 (71%) voluntarily withdrew from the screening process, 54 (17%) were screened out for medical or psychological reasons, and 38 (12%) entered the active donor pool. The total cost to bring a single donor into the program was approximately 1,869 dollars.

CONCLUSION(S)

There was significant attrition in the screening process for oocyte donation that needs to be taken into account in determining the costs of managing the program.

Chemoprevention of colon cancer carcinogenesis by balsalazide: inhibition of azoxymethane-induced aberrant crypt formation in the rat colon and intestinal tumor formation in the B6-Min/+ mouse

Non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin have been shown to suppress colon carcinogenesis and in some cases reduce the size of colorectal polyps. Balsalazide disodium (BSZ) is a colon-specific prodrug of the salicylate, 5-aminosalicylic acid. The aim of the present study was to test the chemopreventive activity of BSZ in two established animal models of colon tumorigenesis, azoxymethane-induced aberrant crypt formation in the rat and intestinal tumor formation in the B6-Min/+ mouse. Aberrant crypt foci (ACF) were induced in Fischer 344 rats via 2 subcutaneous injections of azoxymethane (20 mg/kg). BSZ was supplied in the drinking water for 8 weeks and ACF quantitated. B6-Min/+ mice were treated from 55 days of age for 90 days and intestinal tumors scored for number, size and location. BSZ treatment of AOM-injected rats reduced ACF formation in a dose-dependent manner by 60% with the greatest effect observed on ACF with 4 or more crypts. In B6-Min/+ mice a dose-dependent reduction of intestinal tumor number was observed which reached 80% in the distal small intestine and colon. A preliminary mechanistic study in cultured human colon cancer cells showed that both BSZ and 5-ASA inhibited colon cancer cell proliferation in vitro. However, 5-ASA but not BSZ produced changes consistent with the induction of apoptosis. BSZ produces a dose-dependent chemopreventive effect on colon carcinogenesis. A possible mechanism is consistent with the inhibition of cellular proliferation and the induction of apoptosis.

Use of repetitive DNA sequences and the PCR To differentiate Escherichia coli isolates from human and animal sources

The rep-PCR DNA fingerprint technique, which uses repetitive intergenic DNA sequences, was investigated as a way to differentiate between human and animal sources of fecal pollution. BOX and REP primers were used to generate DNA fingerprints from Escherichia coli strains isolated from human and animal sources (geese, ducks, cows, pigs, chickens, and sheep). Our initial studies revealed that the DNA fingerprints obtained with the BOX primer were more effective for grouping E. coli strains than the DNA fingerprints obtained with REP primers. The BOX primer DNA fingerprints of 154 E. coli isolates were analyzed by using the Jaccard band-matching algorithm. Jackknife analysis of the resulting similarity coefficients revealed that 100% of the chicken and cow isolates and between 78 and 90% of the human, goose, duck, pig, and sheep isolates were assigned to the correct source groups. A dendrogram constructed by using Jaccard similarity coefficients almost completely separated the human isolates from the nonhuman isolates. Multivariate analysis of variance, a form of discriminant analysis, successfully differentiated the isolates and placed them in the appropriate source groups. Taken together, our results indicate that rep-PCR performed with the BOX A1R primer may be a useful and effective tool for rapidly determining sources of fecal pollution.

Dietary copper primarily affects antioxidant capacity and dietary iron mainly affects iron status in a surface response study of female rats fed varying concentrations of iron, zinc and copper

This study was designed to examine the interactions among dietary iron (Fe), copper (Cu), and zinc (Zn) and their effects on Fe status and oxidative stress in female rats. In a three-factor central composite response surface design, rats were assigned to 15 groups and fed modified AIN-93G basal diets with varying amounts of Fe and Zn (7.0, 15.5, 45.8, 135.6, or 300 micrograms/g diet) and Cu (0.5, 1.1, 3.2, 9.2, or 20 micrograms/g diet) for 6 wk. Variations in hemoglobin, hematocrit, and serum ferritin were mainly related to dietary Fe. Liver nonheme Fe was directly affected by dietary Fe and was slightly attenuated by interactions between Cu and Zn, and Zn and Fe. Serum ceruloplasmin activity was primarily determined by an interaction between Cu and Zn with substantial moderation by the quadratic effect of dietary Cu. Liver and heart total superoxide dismutase (SOD) and Cu/Zn SOD activities were directly affected by dietary Cu. Dietary Fe was the only significant, yet weak, predictor of liver thiobarbituric acid reactive substances (TBARS) and vitamin E content and serum triacylglycerols. Variability in serum Cu was mostly determined by the interaction between Cu and Fe, with modification from the quadratic effect of dietary Cu. Serum Zn varied with dietary Zn with a small negative influence from the interaction between Cu and Fe. In summary, Fe status was minimally influenced by dietary Zn or Cu, and Fe intakes 10-fold greater than required did not induce overt oxidative stress in female rats. In addition, measures of antioxidant capacity were primarily influenced by dietary Cu and were optimal at moderate intakes of this micronutrient.

Zinc absorption, mineral balance, and blood lipids in women consuming controlled lactoovovegetarian and omnivorous diets for 8 wk

Zinc absorption, mineral balance, and blood lipid concentrations were measured in 21 women aged 33 +/- 7 y (range: 20-42 y) consuming controlled lactoovovegetarian and nonvegetarian diets for 8 wk each in a crossover design. The lactoovovegetarian and nonvegetarian diets, respectively, provided (by analysis) 973 and 995 mg Ca, 1.8 and 1.3 mg Cu, 367 and 260 mg Mg, 5.9 and 2.5 mg Mn, 1457 and 1667 mg P, 9.1 and 11.1 mg Zn, and (by calculation) 40 and 16 g dietary fiber, 2.5 and 0.8 mmol phytic acid, molar ratios of phytate to Zn of 14 and 5, and millimolar ratios of (phytate x Ca) to Zn of 344 and 111. Dietary zinc absorption was measured by extrinsic isotopic labeling and whole-body counting. Plasma cholesterol, cholesterol fractions, and lipoproteins were reduced 7-12% with the lactoovovegetarian diet, consistent with predictions based on dietary cholesterol and fat. Blood pressure was unaffected. Calcium, copper, magnesium, and phosphorus balances were not different between diets; manganese balance tended to be greater with the lactoovovegetarian diet (P < 0.07). The lactoovovegetarian diet was associated with a 21% reduction in absorptive efficiency that, together with a 14% reduction in dietary zinc, reduced the amount of zinc absorbed by 35% (2.4 compared with 3.7 mg/d) and reduced plasma zinc by 5% within the normal range. Zinc balance was maintained with both diets. Although there is a greater risk of zinc deficiency in persons consuming lactoovovegetarian compared with omnivorous diets, with inclusion of whole grains and legumes zinc requirements can be met and zinc balance maintained.

Effect of age and caloric restriction on cutaneous wound closure in rats and monkeys

Cutaneous wounds close more slowly in rats and monkeys as age increases. Caloric restriction of 40% in rats and 30% in monkeys did not significantly affect healing rates, although it did exert a trend toward faster closure. Similarly, voluntary exercise did not significantly alter healing rates in rats. Thus, impaired wound healing appears to be a generalized physiological manifestation of aging, but its possible amelioration by "anti-aging" interventions remains to be established.

Endocrine neoplasia in New World primates

Of 1,106 New World primates necropsied from the National Zoological Park (Washington, D.C.) and the Department of Comparative Pathology, Johns Hopkins University School of Medicine (Baltimore, Maryland) 22 (1.9%) animals were identified with 27 neoplasms. Of this group, nine animals (two females, seven males) had a total of 13 endocrine neoplasms. All animals were adults, with an age range of 2.7-25 years (average, 12.1 years). Seven were Callitrichidae and two were Cebidae. The adrenal gland was the most affected organ, with seven (53.8%) neoplasms, followed by the pituitary and thyroid gland with two (15.4%) cases each, and the pancreas and parathyroid gland with one tumor (7.7%) each. All neoplastic disorders were benign. Immunocytochemistry assays for growth hormone, adrenocorticotropic hormone, prolactin, follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, and chromogranin A were performed on two pituitary neoplasms. Pheochromocytoma was the most frequent neoplasm, representing 5 (38.4%) of the 13 neoplasms. The remaining were thyroid cystadenoma (two, 15.4%), corticotrophic cell pituitary adenoma (two, 15.4%), adrenal ganglioneuroma (one, 7.7%), adrenal cortical adenoma (one, 7.7%), parathyroid chief-cell adenoma (one, 7.7%), and pancreatic islet-cell adenoma (one, 7.7%).

High- versus low-meat diets: effects on zinc absorption, iron status, and calcium, copper, iron, magnesium, manganese, nitrogen, phosphorus, and zinc balance in postmenopausal women

The effects of three diets--high meat (HM), low meat (LM), or low meat with mineral supplements (LS)--on zinc absorption, elemental balance, and related clinical indexes were investigated in a metabolic study of 14 women aged 51-70 y. The women ate each of the three diets for 7 wk in random order. Lean beef, chicken, ham, and tuna in the HM diet replaced foods with a low mineral content in the LM diet. The LS diet was similar to the HM diet in K, P, Fe, Mg, and Zn contents. Compared with the other diets, the HM diet increased zinc absorption and retention, and slightly increased urinary zinc. Nitrogen and calcium balances and urinary calcium were not different for the HM and LM diets. Iron balance was not different for the HM and LS diets with similar iron content, but the HM diet was unexpectedly associated with lower iron status (higher iron-binding capacity and lower ferritin than LM and LS diets). These results indicate that 0.8 g protein/kg body wt meets protein requirements in older women, and that high meat consumption increases zinc retention without compromising calcium status and may reduce indexes of iron status, in contrast with iron absorption results from studies with radiolabeled test meals.

Structure of the human urokinase receptor gene and its similarity to CD59 and the Ly-6 family

Urokinase plasminogen activator receptor (uPAR) gene expression has been implicated in many important biological processes including cell invasiveness and migration. The uPAR gene was cloned from a human genomic library by hybridization with a uPAR cDNA. The complete structure of the human uPAR gene, including a 21.23-kb transcription unit with 204 bp 5' and 239 bp 3' flanking sequences, was determined by comparison with the uPAR cDNA sequence. The uPAR gene is composed of seven exons and six introns. The seven exons of 101, 111, 144, 162, 135, 147 and 563 bp are separated by six introns of approximately 2.04, 2.62, 8.42, 0.906, 3.10 and 2.78 kb. Exons 1-7 encode 19, 37, 48, 54, 45, 49 and 83 amino acid residues, respectively. A CpG-rich island and sequences related to the transcription factors AP-1, AP-2, c-Jun and NF kappa B are present, but no potential TATA or CAAT boxes were found in the proximal 5' region of the uPAR gene. Comparison of the exon organization of the uPAR gene with that of human CD59 and murine Ly-6 reveals similarity to all three domains encoded by the uPAR exons (2 + 3), (4 + 5) and (6 + 7). These data enable elucidation of the mechanisms involved in regulation of the uPAR gene expression and provide further evidence that the uPAR gene belongs to the Ly-6 superfamily.

Sex affects manganese absorption and retention by humans from a diet adequate in manganese

Men (n = 20) and women (n = 20) consuming a diet adequate in manganese were fed 0.037 mBq 54Mn in a test meal. Subjects were counted in a whole-body counter for 70 d to determine whole-body retention of 54Mn. Data from days 10 to 20 and from days 19 to 70 were analyzed by linear regression to calculate absorption and biological half-life. Men absorbed significantly less 54Mn than women, but the 54Mn absorbed had a longer half-life in men. Estimates of absorption were higher, and estimates of half-life were lower, when data from days 10 to 20 were used compared with days 19 to 70. There was a significant association between manganese absorption and plasma ferritin concentrations and between manganese absorption and biological half-life. We conclude that men and women differ in manganese metabolism and that such differences may be related to iron status. We also conclude that regression estimates of absorption determined by using whole-body retention curves depend on the portion of the data used.

Effect of ascorbic acid on apparent iron absorption by women with low iron stores

The effect of ascorbic acid supplementation on apparent iron absorption was tested in women with low iron stores. For 10 wk, 25 healthy nonpregnant women, aged 20-45 y with low serum ferritin (3.5-17.7 micrograms/L), consumed either a diet with predicted poorly bioavailable iron or a typical Western diet, classified according to dietary meat and ascorbic acid contents. Meals were supplemented with ascorbic acid (500 mg, three times a day) for 5 of the 10 wk, in a double-blind, crossover design. Ascorbic acid did not affect most biochemical indexes of iron status, the biological half-life of 59Fe, or apparent iron absorption (diet-feces) from either diet, but slightly increased serum ferritin (11.9 vs 10.7 micrograms/L, P < 0.06) when data from both diets were combined. These results support other evidence that ascorbic acid has less effect on iron bioavailability than has been predicted from tests with single meals.

Severe or marginal iron deficiency affects spontaneous physical activity in rats

The influence of dietary iron on spontaneous activity was investigated in growing rats. Male rats weighing 97 +/- 10 g fed diets containing 4.6 (deficient), 19.9 (marginal), and 108.4 (adequate) mg Fe/kg diet for 8 wks had hemoglobin values of 52 +/- 6, 152 +/- 4, and 159 +/- 6 g/L, and liver nonheme iron concentrations of 0.79 +/- 0.24, 1.36 +/- 0.39, and 4.58 +/- 0.62 mumol/g, respectively. Body weights were affected only at the lowest iron intake. Diurnal activity was not reversed by iron status; all animals were more active during the dark cycle than the light cycle. Iron deficiency resulted in less time and frequency of horizontal, vertical, and stereotypic movements; less distance moved; and less frequent rotations. Movement speed of iron-deficient rats was faster during early iron deficiency. In the light, rats with marginal iron nutriture were generally more active than were iron-deficient or iron-adequate animals. In the dark, activity generally decreased with each reduction in dietary iron.

Aging of a class of arteries in various mammalian species in relation to the life span

Age-related sclerosis of human renocortical arteries is associated with essential hypertension and limitation of the life span by cardiovascular mortality. Arteries in the kidneys of nonprimate species, examined here, showed near absence of arteriosclerosis when the average life span was less than 12 years and small amounts of sclerosis in longer-lived species. The fastest progression of arteriosclerosis was, paradoxically, in the longest-lived species, the human and the macaque. Results are incompatible with theories of aging that include arteriosclerosis within the framework of mechanisms that are proposed to explain the life spans of species.