Relation of changes in amount and type of dietary fat to fecapentaenes in premenopausal women

Correlation studies suggest that fecal mutagenicity is increased in groups eating high-fat diets, the same groups who are often found to have high colorectal cancer incidence and mortality. The fecapentaenes are the best characterized class of fecal mutagens, but the relationship of dietary fat intake to the excretion of these potent genotoxins is unknown. We studied the effect of changes in amount and type of dietary fat on fecapentaene levels in 31 premenopausal women 20-40 years of age who participated in a controlled feeding study. After a pre-diet free-living period lasting 1 menstrual cycle, women were placed on a high-fat (40% energy from fat) diet for 4 menstrual cycles and then switched to a low-fat (20% energy from fat) diet for an additional 4 menstrual cycles. One-half the subjects were maintained throughout the study at a ratio of polyunsaturated-to-saturated fatty acids (P/S ratio) of 1.0, the other half at 0.3; body weight was constant. All meals during the controlled diet periods were prepared at the Human Study Facility of the Beltsville Human Nutrition Research Center. Fecapentaene and fecapentaene precursor levels were measured in acetone extracts from 3-day pooled stool samples collected during the study. No differences in fecapentaene or precursor levels were observed between the high- and low-fat diets at either P/S ratio. Fecapentaene and precursor levels were higher while on controlled diets than during the pre-diet free-living period, and levels declined again in the post-diet free-living period. We conclude that dietary fat has no significant effect on fecapentaene or precursor levels in acetone extracts of stool in premenopausal women. The effect of other dietary or non-dietary factors on fecapentaenes remains unknown.     

Adiponectin and negative mood in healthy premenopausal and postmenopausal women

Negative mood and stress are associated with cardiovascular and metabolic disease. There are likely many physiological mechanisms underlying the poor health outcomes. The relationship of psychological states (negative mood, life stress, and stress-responsive hormones) and adiponectin, an adipokine that promotes insulin sensitivity, was investigated in two separate studies. The two groups of participants included 52 healthy, premenopausal women, and 63 postmenopausal women with a range of stress levels. The relationship between adiponectin and psychological state (perceived stress and negative mood) was examined cross-sectionally in both groups of participants, but also prospectively (1 year later) in the group of postmenopausal women.In premenopausal women, negative mood and nocturnal urinary epinephrine were significantly related to adiponectin, independent of BMI. In postmenopausal women, negative mood was not associated with adiponectin cross-sectionally, but negative mood was a significant predictor for lower levels of adiponectin 1 year later, independent of initial adiponectin concentrations and changes in body mass index. Lastly, having a depressive disorder was related to lower adiponectin. As adiponectin levels are associated with insulin resistance, obesity, and diabetes mellitus, these findings suggest there may be an adiponectin-mediated pathway explaining in part how negative mood affects metabolic health. Mechanistic studies are needed to explore this potential relationship further.     

Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women

The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P < 0.01) associated with smaller sizes of the central and the lesser peripheral Zn pools, faster disappearance of tracer from plasma, and higher transfer rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn <10.7 micromol/l or 700 ng/ml had decreased thresholds of electrical stimulation for gustatory nerves. Our results based on Zn kinetics support the conventional cutoff value of plasma Zn (10.7 micromol/l or 700 ng/ml) between normal and low Zn status.     

Endogenous oestrogens and breast cancer risk in premenopausal and postmenopausal women

Breast cancer risk is strongly related to several reproductive and hormonal factors, but the nature of the effects of endogenous oestrogens has been difficult to establish. Data are now available from several large prospective studies with biobanks of stored serum, enabling better characterization of the associations of endogenous oestrogens, and other endogenous hormones, with breast cancer risk. In postmenopausal women, relatively high serum concentrations of oestradiol are associated with a more than twofold increase in the risk for breast cancer, and this probably explains the increase in risk in obese postmenopausal women. In premenopausal women the data available on oestrogens are more limited and difficult to interpret due to the large variations in endogenous oestrogens during the menstrual cycle, but are compatible with a positive association between oestradiol and breast cancer risk. There is also evidence that breast cancer risk is positively associated with androgens, prolactin and insulin-like growth factor-I. Further data are required, with better assays and repeat measures, to provide more accurate estimates of risk and to clarify the role of oestrogens in premenopausal women and the roles of other endogenous hormones.     

Skeletal muscle fat oxidation is increased in African-American and white women after 10 days of endurance exercise training

Objective: Obesity is associated with lower rates of skeletal muscle fatty acid oxidation (FAO), which is linked to insulin resistance. FAO is reduced further in obese African‐American (AAW) vs. white women (CW) and may also be lower in lean AAW vs. CW. In lean CW, endurance exercise training (EET) elevates the oxidative capacity of skeletal muscle. Therefore, we determined whether EET would elevate skeletal muscle FAO similarly in AAW and CW with a lower lipid oxidative capacity. Research Methods and Procedures: In vitro rates of FAO were assessed in rectus abdominus muscle strips using [1‐¹⁴C] palmitate (Pal) from lean AAW [BMI = 24.2 ± 0.9 (standard error) kg/m²] and CW (23.6 ± 0.8 kg/m²) undergoing voluntary abdominal surgery. Lean AAW (22 ± 0.9 kg/m²) and CW (24 ± 0.8 kg/m²) and obese AAW (36 ± 1.2 kg/m²) and CW (40 ± 1.3 kg/m²) underwent 10 consecutive days of EET on a cycle ergometer (60 min/d, 75% peak oxygen uptake). FAO was measured in vastus lateralis homogenates as captured ¹⁴CO₂ using [1‐¹⁴C] Pal, palmitoyl‐CoA (Pal‐CoA), and palmityl‐carnitine (Pal‐Car). Results: Muscle strip experiments showed suppressed rates of FAO (p = 0.03) in lean AAW vs. CW. EET increased the rates of skeletal muscle Pal oxidation (p = 0.05) in both lean AAW and CW. In obese subjects, Pre‐EET Pal (but not Pal‐CoA or Pal‐Car) oxidation was lower (p = 0.05) in AAW vs. CW. EET increased Pal oxidation 100% in obese AAW (p < 0.05) and 59% (p < 0.05) in obese CW. Similar increases (p < 0.05) in post‐EET FAO were observed for Pal‐CoA and Pal‐Car in both groups. Discussion: Both lean and obese AAW possess a lower capacity for skeletal muscle FAO, but EET increases FAO similarly in both AAW and CW. These data suggest the use of EET for treatment against obesity and diabetes for both AAW and CW.     

Acute changes in blood lipids and enzymes in postmenopausal women after exercise.

The effectiveness of lifestyle intervention strategies to improve blood lipids in women may be dependent on preexisting cholesterol concentrations. We characterized the effects of cholesterol status on blood lipid, lipoprotein lipid, and lipid regulatory enzyme responses to a single session of aerobic exercise in physically active, postmenopausal women. In this study, blood samples were obtained from 12 women with high cholesterol (HC; > or =200 mg/dl) and 13 women with normal cholesterol (NC; <200 mg/dl), 24 h before (Pre), immediately after (IPE), and 24 and 48 h after an exercise session (treadmill walking at 70% peak oxygen consumption, 400 kcal). We found that repeated-measures analysis revealed the following: 1) preexercise cholesterol differences did not influence the lipid or lipoprotein lipid responses to exercise; 2) for both groups, triglyceride was significantly reduced (-8.5%) after exercise; 3) the concentration profile over time for high-density lipoprotein cholesterol was significant for both groups, first falling at IPE then rising back to Pre levels by 24 h after exercise; 4) the lecithin-cholesterol acyltransferase activity (LCATA) exercise response was group dependent, increasing modestly in the NC group at 24 and 48 h; 5) lipoprotein lipase activity (LPLA) increased at IPE (by 17%) in the HC group only and then fell at 24 and 48 h (by 21%) compared with Pre; and 6) cholesterol ester transfer protein activity was unchanged by exercise. From these findings, we conclude that in postmenopausal women, a single session of endurance exercise elicited a short-term, favorable decrease in triglycerides independent of initial blood cholesterol concentrations. However, LCATA and LPLA postexercise changes were influenced by preexercise cholesterol status.     

Body dimensions and thyroid hormone levels in premenopausal and postmenopausal women from Austria

Correlations between thyroid hormone levels and body dimensions were investigated in a group of 124 premenopausal (ages 16–40 years) and 142 postmenopausal (ages 38–61 years) women from Vienna, Austria. Twenty-nine absolute body dimensions and thirteen anthropometric indices were correlated with the serum levels of thyroxine, triiodothyronine, thyroid-stimulating hormone, and thyroid-hormone-binding globulin as well as three hormone ratios (T3/T4, T4/TSH, T3/TSH). All hormones exhibited statistically significant correlations with 24 anthropometric variables and 11 indices. The correlations between thyroxine and triiodothyronine levels and the body measurements were predominantly positive in both proband groups. Higher thyroid hormone levels were associated positively with body dimensions, especially with the amount of subcutaneous fat tissue, in adult females independently of their menstrual status. The direction of the correlations between thyroid-stimulating hormone and body measures as well as anthropometric indices differed between the premenopausal and the postmenopausal women. While in premenopausal women mainly positive correlations between anthropometric characters and the level of thyroid stimulating hormone occur, in postmenopausal women most of these correlations are negative. This is probably due to the decrease of thyroid-stimulating hormone levels with increasing age, as well as with changes in body shape during the climacteric and after the menopause. © 1994 Wiley-Liss, Inc.     

Aerobic exercise training reduces plasma endothelin-1 concentration in older women.

Endothelial function deteriorates with aging. On the other hand, exercise training improves the function of vascular endothelial cells. Endothelin-1 (ET-1), which is produced by vascular endothelial cells, has potent constrictor and proliferative activity in vascular smooth muscle cells and, therefore, has been implicated in regulation of vascular tonus and progression of atherosclerosis. We previously reported significantly higher plasma ET-1 concentration in middle-aged than in young humans, and recently we showed that plasma ET-1 concentration was significantly decreased by aerobic exercise training in healthy young humans. We hypothesized that plasma ET-1 concentration increases with age, even in healthy adults, and that lifestyle modification (i.e., exercise) can reduce plasma ET-1 concentration in previously sedentary older adults. We measured plasma ET-1 concentration in healthy young women (21-28 yr old), healthy middle-aged women (31-47 yr old), and healthy older women (61-69 yr old). The plasma level of ET-1 significantly increased with aging (1.02 +/- 0.08, 1.33 +/- 0.11, and 2.90 +/- 0.20 pg/ml in young, middle-aged, and older women, respectively). Thus plasma ET-1 concentration was markedly higher in healthy older women than in healthy young or middle-aged women (by approximately 3- and 2-fold, respectively). In healthy older women, we also measured plasma ET-1 concentration after 3 mo of aerobic exercise (cycling on a leg ergometer at 80% of ventilatory threshold for 30 min, 5 days/wk). Regular exercise significantly decreased plasma ET-1 concentration in the healthy older women (2.22 +/- 0.16 pg/ml, P < 0.01) and also significantly reduced their blood pressure. The present study suggests that regular aerobic-endurance exercise reduces plasma ET-1 concentration in older humans, and this reduction in plasma ET-1 concentration may have beneficial effects on the cardiovascular system (i.e., prevention of progression of hypertension and/or atherosclerosis by endogenous ET-1).     

Effect of estrogen supplementation on exercise thermoregulation in premenopausal women

This studyexamined the effects of 3 days of estrogen supplementation (ES) onthermoregulation during exercise in premenopausal (20-39 yr) adultwomen during the follicular phase of the menstrual cycle. Subjects (11 control, 10 experimental) performed upright cycle ergometer exercise at60% of maximal O₂ consumption ina neutral environment (25°C, 30% relative humidity) for 20 min. Subjects were given placebo (P) or -estradiol (2 mg/tablet, 3 tablets/day for 3 days). All experiments were conductedbetween 6:30 and 9:00 AM after ingestion of the last tablet. Heartrate, forearm blood flow (FBF), mean skin temperature, esophagealtemperature (T_es), and forearmsweat rate were measured. Blood analysis for estrogen and progesteronereflected the follicular phase of the menstrual cycle. MaximalO₂ consumption (37.1 ± 6.2 in P vs. 38.4 ± 6.3 ml · kg¹ · min¹in ES) and body weight-to-surface area ratio (35.58 ± 2.85 in P vs.37.3 ± 2.7 in ES) were similar between groups. Synthesis of 70-kDaheat shock protein was not induced by 3 days of ES. Neither thethreshold for sweating (36.97 ± 0.15 in P vs. 36.90 ± 0.22°C in ES), the threshold for an increase in FBF (37.09 ± 0.22 in P vs. 37.17 ± 0.26°C in ES), the slope ofsweat rate-T_es relationship (0.42 ± 0.16 in P vs. 0.41 ± 0.17 in ES), nor the FBF-T_es relationship (10.04 ± 4.4 in P vs. 9.61 ± 3.46 in ES) was affected(P > 0.05) by 3 days of ES. Weconclude that 3 days of ES by young adult women in the follicular phaseof their menstrual cycle have no effect on heat transfer to the skin,heat dissipation by evaporative cooling, or leukocyte synthesis of70-kDa heat shock protein.

     

Substrate utilization during endurance exercise in men and women after endurance training

We investigated the effect of endurance training on whole body substrate, glucose, and glycerol utilization during 90 min of exercise at 60% peak O2 consumption (VO2(peak)) in males and females. Substrate oxidation was determined before and after 7 wk of endurance training on a cycle ergometer, with posttesting performed at the same absolute (ABS, W) and relative (REL, VO2(peak)) intensities. [6,6-2H]glucose and [1,1,2,3,3-2H]glycerol tracers were used to calculate the respective substrate tracee flux. Endurance training resulted in an increase in VO2(peak) for both males and females of 17 and 22%, respectively (P < 0.001). Females demonstrated a lower respiratory exchange ratio (RER) both pretraining and posttraining compared with males during exercise (P < 0.001). Glucose rate of appearance (R(a)) and rate of disappearance (R(d)) were not different between males and females. Glucose metabolic clearance rate (MCR) was lower at 75 and 90 min of exercise for females compared with males (P < 0.05). Glucose R(a) and R(d) were lower during exercise at both ABS and REL posttraining exercise intensities compared with pretraining (P < 0.001). Females had a higher exercise glycerol R(a) and R(d) compared with males both pre- and posttraining (P < 0.001). Glycerol R(a) was not different at either the ABS or REL posttraining exercise intensities compared with pretraining. We concluded that females oxidize proportionately more lipid and less carbohydrate during exercise compared with males both pre- and posttraining, which was cotemporal with a higher glycerol R(a) in females. Furthermore, endurance training resulted in a decrease in glucose flux at both ABS and REL exercise intensities after endurance exercise training.     

The effect of combined aerobic and resistance exercise training on abdominal fat in obese middle-aged women

The purpose of this study was to investigate the effect of combined aerobic and resistance training on abdominal fat. Our participants in the study consisted of thirty obese women. They were separated into three groups: a control group (n=10), an aerobic training group (n=10) and a combined training group (n=10). The aerobic training group was composed of 60-70% HRmax (intensity), 60 minutes a day (duration) for 6 days a week (frequency). The combined training group was separated into resistance training (3 days a week, Mon, Wed, Fri) and the aerobic training (3 days a week, Tue, Thu, Sat). The levels for abdominal fat volume were measured by determining the subcutaneous fat volume (SFV), visceral fat volume (VFV), and VFV/SFV by CT (computed tomography). The VO(2max) was significantly (p<0.05) increased in both groups. The subcutaneous fat and visceral fat levels were decreased in the combined training group more than in the aerobics training group. Also, the lean body mass (LBM) was significantly increased only in the combined training group. In addition, the total cholesterol, triglyceride and LDL-C were significantly (p<.05) decreased and the HDL-C was significantly (p<.05) increased in both groups. In conclusion, our results observed that combined training decreased abdominal subcutaneous fat and visceral fat more than aerobic training only.     

Expression of estrogen receptor alpha and beta in myometrium of premenopausal and postmenopausal women

Although a clear role for estrogen receptor (ER) alpha has been established, the contribution of ERbeta in estrogen-dependent development, growth and functions of the myometrium is not understood. As a first step towards understanding the role of ERbeta, we have examined the expression of ERalpha and ERbeta in the human myometrium. With competitive RT-PCR assays, the level of ERbeta mRNA was 10-200 times lower than that of ERalpha mRNA in both premenopausal and postmenopausal myometrium. In premenopausal myometrium, the expression pattern of ERbeta mRNA during the menstrual cycle was similar to that of ERalpha mRNA, with highest levels in peri-ovulatory phase. In postmenopausal myometrium, ERbeta mRNA was significantly higher than it was in premenopausal myometrium, while the level of ERalpha mRNA was lower. The net result was a change in the ratio of ERbeta to ERalpha mRNA expression. The ratio changed from 0.6-1.5 in premenopausal to 2.5-7.6 in postmenopausal myometrium. In premenopausal women, the gonadotropin releasing hormone analogue, leuprorelin acetate, elicited a decrease in ERalpha and an increase in ERbeta mRNA expression to cause a postmenopausal receptor phenotype. Estradiol, on the other hand, reversed ERalpha and ERbeta mRNA expression and their ratio in postmenopausal myometrium to those of premenopausal myometrium. Immunohistochemical staining and Western blot analysis of ERalpha and ERbeta with semiquantitative analysis showed good agreement between mRNA and protein levels. The data indicate that coordinated expression of ERalpha and ERbeta might be necessary for normal estrogen action in myometrium. Furthermore, estrogen appears a dominant regulator of both receptors in the myometrium.     

Twenty-four-hour ghrelin is elevated after calorie restriction and exercise training in non-obese women

Objective: The purpose of this study was to determine whether chronic energy deficiency achieved with caloric restriction combined with exercise is associated with changes in the 24‐hour profile of ghrelin in non‐obese, pre‐menopausal women. Research Methods and Procedures: Twelve non‐obese (BMI = 18 to 25 kg/m²), non‐exercising women (age, 18 to 24 years) were randomly assigned to a non‐exercising control group or a diet and exercise group. The 3‐month diet and exercise intervention yielded a daily energy deficit of ?45.7 ± 12.4%. Serial measurements were made of body composition, energy balance, and feelings of fullness. Repeated blood sampling over 24 hours to measure ghrelin occurred before and after the study. Results: Significant decreases in body weight, body fat, and feelings of fullness were observed in only the energy‐deficit group (p < 0.05); significant changes in the following ghrelin features were found in only the deficit group (p < 0.05): elevations in baseline (+353 ± 118 pg/mL), lunch peak (+370 ± 102 pg/mL), dinner peak (+438 ± 149 pg/mL), nocturnal rise (+269 ± 77 pg/mL), and nocturnal peak (+510 ± 143 pg/mL). In addition, we found a larger dinner decline (?197 ± 52 pg/mL) and negative correlations between changes in the ghrelin dinner profile and changes in body weight (R = 0.784), 24‐hour intake (R = 0.67), energy deficiency (R = 0.762), and feelings of fullness (R = 0.648; p < 0.05). Discussion: Changes in ghrelin concentrations across the day after weight loss are closely associated with other physiological adaptations to energy deficiency, further supporting the role of ghrelin as a countermeasure to restore energy balance.     

Alkaline phosphatase and percentage body fat predict circulating C-reactive protein in premenopausal women

C-reactive protein (CRP) is considered a marker of inflammation, which is a risk factor for many chronic diseases. However, determinants of CRP remain unclear and were studied in a strictly defined cohort of healthy premenopausal women (n=233) using multiple regression models. Independent predictors of serum CRP (model R²=0.59) were percentage body fat, serum alkaline phosphatase (ALP), sex hormone-binding globulin and white blood cell count. The close association between CRP and ALP suggests that enzymatic activity of ALP may be important for the anti-inflammatory effects of CRP, which should be confirmed with additional studies.     

Femoral artery remodeling after aerobic exercise training without weight loss in women

Background

It is currently unclear whether reductions in adiposity mediate the improvements in vascular health that occur with aerobic exercise. The purpose of this longitudinal study of 13 healthy women (33 ± 4 years old) was to determine whether 14 weeks of aerobic exercise would alter functional measures of vascular health, namely resting aortic pulse wave velocity (aPWV, an index of arterial stiffness), femoral artery diameter (D_FA), and femoral artery blood flow (BF_FA) independent of changes in adiposity.

Methods

Aerobic fitness was assessed as VO₂peak normalized to fat-free mass, and adiposity (percent body fat) was determined by dual energy x-ray absorptiometry. Serum concentrations of proteins associated with risk for cardiovascular disease, including C-reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), and leptin, were also measured. Subjects cycled for 50 minutes, 3 times per week.

Results

Aerobic fitness normalized to fat-free mass increased 6% (P = 0.03) whereas adiposity did not change. Resting D_FA increased 12% (P < 0.001) and resting shear rate decreased 28% (P = 0.007). Aortic PWV, and serum sICAM-1, CRP and leptin did not change with training.

Conclusion

Significant reductions in adiposity were not necessary for aerobic exercise training to bring about improvements in aerobic fitness and arterial remodeling. Peripheral arterial remodeling occurred without changes in central arterial stiffness or markers of inflammation.

     

The effects of different exercise training modalities on plasma proenkephalin Peptide F in women

Due to the important interactions of proenkephalin fragments (e.g., proenkephalin [107–140] Peptide F) to enhance activation of immune cells and potentially combat pain associated with exercise-induced muscle tissue damage, we examined the differential plasma responses of Peptide F to different exercise training programs. Participants were tested pre-training (T1), and after 8 weeks (T2) of training. Fifty-nine healthy women were matched and then randomly assigned to one of four groups: heavy resistance strength training (STR, n = 18), high intensity endurance training (END, n = 14), combined strength and endurance training (CMB, n = 17), or control (CON, n = 10). Blood was collected using a cannula inserted into a superficial vein in the antecubital fossa with samples collected at rest and immediately after an acute bout of 6 X 10 RM in a squat resistance exercise before training and after training. Prior to any training, no significant differences were observed for any of the groups before or after acute exercise. With training, significant (P ≤ 0.95) elevations were observed with acute exercise in each of the exercise training groups and this effect was significantly greater in the CMB group. These data indicate that in untrained women exercise training will not change resting of plasma Peptide F concentrations unless both forms of exercise are performed but will result in significant increases in the immediate post-exercise responses. Such findings appear to indicate adrenal medullary adaptations opioid production significantly altered with exercise training.